1720e596aSThomas Gleixner // SPDX-License-Identifier: GPL-2.0+ 2a5f4374aSIngo Molnar /* 3a5f4374aSIngo Molnar * User-space Probes (UProbes) 4a5f4374aSIngo Molnar * 535aa621bSIngo Molnar * Copyright (C) IBM Corporation, 2008-2012 6a5f4374aSIngo Molnar * Authors: 7a5f4374aSIngo Molnar * Srikar Dronamraju 8a5f4374aSIngo Molnar * Jim Keniston 990eec103SPeter Zijlstra * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra 10a5f4374aSIngo Molnar */ 11a5f4374aSIngo Molnar 12a5f4374aSIngo Molnar #include <linux/kernel.h> 13a5f4374aSIngo Molnar #include <linux/highmem.h> 14a5f4374aSIngo Molnar #include <linux/pagemap.h> /* read_mapping_page */ 15a5f4374aSIngo Molnar #include <linux/slab.h> 16a5f4374aSIngo Molnar #include <linux/sched.h> 176e84f315SIngo Molnar #include <linux/sched/mm.h> 18f7ccbae4SIngo Molnar #include <linux/sched/coredump.h> 19e8440c14SJosh Stone #include <linux/export.h> 20a5f4374aSIngo Molnar #include <linux/rmap.h> /* anon_vma_prepare */ 21a5f4374aSIngo Molnar #include <linux/mmu_notifier.h> /* set_pte_at_notify */ 22a5f4374aSIngo Molnar #include <linux/swap.h> /* try_to_free_swap */ 230326f5a9SSrikar Dronamraju #include <linux/ptrace.h> /* user_enable_single_step */ 240326f5a9SSrikar Dronamraju #include <linux/kdebug.h> /* notifier mechanism */ 25194f8dcbSOleg Nesterov #include "../../mm/internal.h" /* munlock_vma_page */ 2632cdba1eSOleg Nesterov #include <linux/percpu-rwsem.h> 27aa59c53fSOleg Nesterov #include <linux/task_work.h> 2840814f68SOleg Nesterov #include <linux/shmem_fs.h> 29f385cb85SSong Liu #include <linux/khugepaged.h> 30a5f4374aSIngo Molnar 31a5f4374aSIngo Molnar #include <linux/uprobes.h> 32a5f4374aSIngo Molnar 33d4b3b638SSrikar Dronamraju #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) 34d4b3b638SSrikar Dronamraju #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE 35d4b3b638SSrikar Dronamraju 36a5f4374aSIngo Molnar static struct rb_root uprobes_tree = RB_ROOT; 37441f1eb7SOleg Nesterov /* 38441f1eb7SOleg Nesterov * allows us to skip the uprobe_mmap if there are no uprobe events active 39441f1eb7SOleg Nesterov * at this time. Probably a fine grained per inode count is better? 40441f1eb7SOleg Nesterov */ 41441f1eb7SOleg Nesterov #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) 42a5f4374aSIngo Molnar 43a5f4374aSIngo Molnar static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ 44a5f4374aSIngo Molnar 45a5f4374aSIngo Molnar #define UPROBES_HASH_SZ 13 46a5f4374aSIngo Molnar /* serialize uprobe->pending_list */ 47a5f4374aSIngo Molnar static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; 48a5f4374aSIngo Molnar #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 49a5f4374aSIngo Molnar 502bf1acc2SOleg Nesterov DEFINE_STATIC_PERCPU_RWSEM(dup_mmap_sem); 5132cdba1eSOleg Nesterov 52cb9a19feSOleg Nesterov /* Have a copy of original instruction */ 5371434f2fSOleg Nesterov #define UPROBE_COPY_INSN 0 54cb9a19feSOleg Nesterov 553ff54efdSSrikar Dronamraju struct uprobe { 563ff54efdSSrikar Dronamraju struct rb_node rb_node; /* node in the rb tree */ 57ce59b8e9SElena Reshetova refcount_t ref; 58e591c8d7SOleg Nesterov struct rw_semaphore register_rwsem; 593ff54efdSSrikar Dronamraju struct rw_semaphore consumer_rwsem; 603ff54efdSSrikar Dronamraju struct list_head pending_list; 613ff54efdSSrikar Dronamraju struct uprobe_consumer *consumers; 623ff54efdSSrikar Dronamraju struct inode *inode; /* Also hold a ref to inode */ 633ff54efdSSrikar Dronamraju loff_t offset; 641cc33161SRavi Bangoria loff_t ref_ctr_offset; 6571434f2fSOleg Nesterov unsigned long flags; 66ad439356SOleg Nesterov 67ad439356SOleg Nesterov /* 68ad439356SOleg Nesterov * The generic code assumes that it has two members of unknown type 69ad439356SOleg Nesterov * owned by the arch-specific code: 70ad439356SOleg Nesterov * 71ad439356SOleg Nesterov * insn - copy_insn() saves the original instruction here for 72ad439356SOleg Nesterov * arch_uprobe_analyze_insn(). 73ad439356SOleg Nesterov * 74ad439356SOleg Nesterov * ixol - potentially modified instruction to execute out of 75ad439356SOleg Nesterov * line, copied to xol_area by xol_get_insn_slot(). 76ad439356SOleg Nesterov */ 773ff54efdSSrikar Dronamraju struct arch_uprobe arch; 783ff54efdSSrikar Dronamraju }; 793ff54efdSSrikar Dronamraju 801cc33161SRavi Bangoria struct delayed_uprobe { 811cc33161SRavi Bangoria struct list_head list; 821cc33161SRavi Bangoria struct uprobe *uprobe; 831cc33161SRavi Bangoria struct mm_struct *mm; 841cc33161SRavi Bangoria }; 851cc33161SRavi Bangoria 861cc33161SRavi Bangoria static DEFINE_MUTEX(delayed_uprobe_lock); 871cc33161SRavi Bangoria static LIST_HEAD(delayed_uprobe_list); 881cc33161SRavi Bangoria 89a5f4374aSIngo Molnar /* 90ad439356SOleg Nesterov * Execute out of line area: anonymous executable mapping installed 91ad439356SOleg Nesterov * by the probed task to execute the copy of the original instruction 92ad439356SOleg Nesterov * mangled by set_swbp(). 93ad439356SOleg Nesterov * 94c912dae6SOleg Nesterov * On a breakpoint hit, thread contests for a slot. It frees the 95c912dae6SOleg Nesterov * slot after singlestep. Currently a fixed number of slots are 96c912dae6SOleg Nesterov * allocated. 97c912dae6SOleg Nesterov */ 98c912dae6SOleg Nesterov struct xol_area { 99c912dae6SOleg Nesterov wait_queue_head_t wq; /* if all slots are busy */ 100c912dae6SOleg Nesterov atomic_t slot_count; /* number of in-use slots */ 101c912dae6SOleg Nesterov unsigned long *bitmap; /* 0 = free slot */ 102c912dae6SOleg Nesterov 103704bde3cSOleg Nesterov struct vm_special_mapping xol_mapping; 104704bde3cSOleg Nesterov struct page *pages[2]; 105c912dae6SOleg Nesterov /* 106c912dae6SOleg Nesterov * We keep the vma's vm_start rather than a pointer to the vma 107c912dae6SOleg Nesterov * itself. The probed process or a naughty kernel module could make 108c912dae6SOleg Nesterov * the vma go away, and we must handle that reasonably gracefully. 109c912dae6SOleg Nesterov */ 110c912dae6SOleg Nesterov unsigned long vaddr; /* Page(s) of instruction slots */ 111c912dae6SOleg Nesterov }; 112c912dae6SOleg Nesterov 113c912dae6SOleg Nesterov /* 114a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 115a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 116a5f4374aSIngo Molnar * changed after breakpoint was inserted. 117a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 118a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 119a5f4374aSIngo Molnar * executable vma. 120a5f4374aSIngo Molnar */ 121a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 122a5f4374aSIngo Molnar { 12313f59c5eSOleg Nesterov vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; 124a5f4374aSIngo Molnar 125e40cfce6SOleg Nesterov if (is_register) 126e40cfce6SOleg Nesterov flags |= VM_WRITE; 127a5f4374aSIngo Molnar 128e40cfce6SOleg Nesterov return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; 129a5f4374aSIngo Molnar } 130a5f4374aSIngo Molnar 13157683f72SOleg Nesterov static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) 132a5f4374aSIngo Molnar { 13357683f72SOleg Nesterov return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); 134a5f4374aSIngo Molnar } 135a5f4374aSIngo Molnar 136cb113b47SOleg Nesterov static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) 137cb113b47SOleg Nesterov { 138cb113b47SOleg Nesterov return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); 139cb113b47SOleg Nesterov } 140cb113b47SOleg Nesterov 141a5f4374aSIngo Molnar /** 142a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 143a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 144a5f4374aSIngo Molnar * 145a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 146c517ee74SOleg Nesterov * @addr: address the old @page is mapped at 147fb4fb04fSSong Liu * @old_page: the page we are replacing by new_page 148fb4fb04fSSong Liu * @new_page: the modified page we replace page by 149a5f4374aSIngo Molnar * 150fb4fb04fSSong Liu * If @new_page is NULL, only unmap @old_page. 151fb4fb04fSSong Liu * 152fb4fb04fSSong Liu * Returns 0 on success, negative error code otherwise. 153a5f4374aSIngo Molnar */ 154c517ee74SOleg Nesterov static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 155bdfaa2eeSOleg Nesterov struct page *old_page, struct page *new_page) 156a5f4374aSIngo Molnar { 157a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 15814fa2daaSKirill A. Shutemov struct page_vma_mapped_walk pvmw = { 1595a52c9dfSSong Liu .page = compound_head(old_page), 16014fa2daaSKirill A. Shutemov .vma = vma, 16114fa2daaSKirill A. Shutemov .address = addr, 16214fa2daaSKirill A. Shutemov }; 1639f92448cSOleg Nesterov int err; 164ac46d4f3SJérôme Glisse struct mmu_notifier_range range; 16500501b53SJohannes Weiner 1667269f999SJérôme Glisse mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr, 1676f4f13e8SJérôme Glisse addr + PAGE_SIZE); 168ac46d4f3SJérôme Glisse 169fb4fb04fSSong Liu if (new_page) { 170d9eb1ea2SJohannes Weiner err = mem_cgroup_charge(new_page, vma->vm_mm, GFP_KERNEL); 17100501b53SJohannes Weiner if (err) 17200501b53SJohannes Weiner return err; 173fb4fb04fSSong Liu } 174a5f4374aSIngo Molnar 175194f8dcbSOleg Nesterov /* For try_to_free_swap() and munlock_vma_page() below */ 176bdfaa2eeSOleg Nesterov lock_page(old_page); 1779f92448cSOleg Nesterov 178ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_start(&range); 1799f92448cSOleg Nesterov err = -EAGAIN; 1809d82c694SJohannes Weiner if (!page_vma_mapped_walk(&pvmw)) 1819f92448cSOleg Nesterov goto unlock; 18214fa2daaSKirill A. Shutemov VM_BUG_ON_PAGE(addr != pvmw.address, old_page); 183a5f4374aSIngo Molnar 184fb4fb04fSSong Liu if (new_page) { 185bdfaa2eeSOleg Nesterov get_page(new_page); 186be5d0a74SJohannes Weiner page_add_new_anon_rmap(new_page, vma, addr, false); 187b518154eSJoonsoo Kim lru_cache_add_inactive_or_unevictable(new_page, vma); 188fb4fb04fSSong Liu } else 189fb4fb04fSSong Liu /* no new page, just dec_mm_counter for old_page */ 190fb4fb04fSSong Liu dec_mm_counter(mm, MM_ANONPAGES); 191a5f4374aSIngo Molnar 192bdfaa2eeSOleg Nesterov if (!PageAnon(old_page)) { 193bdfaa2eeSOleg Nesterov dec_mm_counter(mm, mm_counter_file(old_page)); 1947396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1957396fa81SSrikar Dronamraju } 1967396fa81SSrikar Dronamraju 19714fa2daaSKirill A. Shutemov flush_cache_page(vma, addr, pte_pfn(*pvmw.pte)); 19814fa2daaSKirill A. Shutemov ptep_clear_flush_notify(vma, addr, pvmw.pte); 199fb4fb04fSSong Liu if (new_page) 20014fa2daaSKirill A. Shutemov set_pte_at_notify(mm, addr, pvmw.pte, 20114fa2daaSKirill A. Shutemov mk_pte(new_page, vma->vm_page_prot)); 202a5f4374aSIngo Molnar 203bdfaa2eeSOleg Nesterov page_remove_rmap(old_page, false); 204bdfaa2eeSOleg Nesterov if (!page_mapped(old_page)) 205bdfaa2eeSOleg Nesterov try_to_free_swap(old_page); 20614fa2daaSKirill A. Shutemov page_vma_mapped_walk_done(&pvmw); 207a5f4374aSIngo Molnar 208c17c3dc9SHugh Dickins if ((vma->vm_flags & VM_LOCKED) && !PageCompound(old_page)) 209bdfaa2eeSOleg Nesterov munlock_vma_page(old_page); 210bdfaa2eeSOleg Nesterov put_page(old_page); 211194f8dcbSOleg Nesterov 2129f92448cSOleg Nesterov err = 0; 2139f92448cSOleg Nesterov unlock: 214ac46d4f3SJérôme Glisse mmu_notifier_invalidate_range_end(&range); 215bdfaa2eeSOleg Nesterov unlock_page(old_page); 2169f92448cSOleg Nesterov return err; 217a5f4374aSIngo Molnar } 218a5f4374aSIngo Molnar 219a5f4374aSIngo Molnar /** 2205cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 221a5f4374aSIngo Molnar * @insn: instruction to be checked. 2225cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 223a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 224a5f4374aSIngo Molnar */ 2255cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 226a5f4374aSIngo Molnar { 2275cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 228a5f4374aSIngo Molnar } 229a5f4374aSIngo Molnar 2300908ad6eSAnanth N Mavinakayanahalli /** 2310908ad6eSAnanth N Mavinakayanahalli * is_trap_insn - check if instruction is breakpoint instruction. 2320908ad6eSAnanth N Mavinakayanahalli * @insn: instruction to be checked. 2330908ad6eSAnanth N Mavinakayanahalli * Default implementation of is_trap_insn 2340908ad6eSAnanth N Mavinakayanahalli * Returns true if @insn is a breakpoint instruction. 2350908ad6eSAnanth N Mavinakayanahalli * 2360908ad6eSAnanth N Mavinakayanahalli * This function is needed for the case where an architecture has multiple 2370908ad6eSAnanth N Mavinakayanahalli * trap instructions (like powerpc). 2380908ad6eSAnanth N Mavinakayanahalli */ 2390908ad6eSAnanth N Mavinakayanahalli bool __weak is_trap_insn(uprobe_opcode_t *insn) 2400908ad6eSAnanth N Mavinakayanahalli { 2410908ad6eSAnanth N Mavinakayanahalli return is_swbp_insn(insn); 2420908ad6eSAnanth N Mavinakayanahalli } 2430908ad6eSAnanth N Mavinakayanahalli 244ab0d805cSOleg Nesterov static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) 245cceb55aaSOleg Nesterov { 246cceb55aaSOleg Nesterov void *kaddr = kmap_atomic(page); 247ab0d805cSOleg Nesterov memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); 248cceb55aaSOleg Nesterov kunmap_atomic(kaddr); 249cceb55aaSOleg Nesterov } 250cceb55aaSOleg Nesterov 2515669cceeSOleg Nesterov static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) 2525669cceeSOleg Nesterov { 2535669cceeSOleg Nesterov void *kaddr = kmap_atomic(page); 2545669cceeSOleg Nesterov memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); 2555669cceeSOleg Nesterov kunmap_atomic(kaddr); 2565669cceeSOleg Nesterov } 2575669cceeSOleg Nesterov 258ed6f6a50SOleg Nesterov static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) 259ed6f6a50SOleg Nesterov { 260ed6f6a50SOleg Nesterov uprobe_opcode_t old_opcode; 261ed6f6a50SOleg Nesterov bool is_swbp; 262ed6f6a50SOleg Nesterov 2630908ad6eSAnanth N Mavinakayanahalli /* 2640908ad6eSAnanth N Mavinakayanahalli * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. 2650908ad6eSAnanth N Mavinakayanahalli * We do not check if it is any other 'trap variant' which could 2660908ad6eSAnanth N Mavinakayanahalli * be conditional trap instruction such as the one powerpc supports. 2670908ad6eSAnanth N Mavinakayanahalli * 2680908ad6eSAnanth N Mavinakayanahalli * The logic is that we do not care if the underlying instruction 2690908ad6eSAnanth N Mavinakayanahalli * is a trap variant; uprobes always wins over any other (gdb) 2700908ad6eSAnanth N Mavinakayanahalli * breakpoint. 2710908ad6eSAnanth N Mavinakayanahalli */ 272ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); 273ed6f6a50SOleg Nesterov is_swbp = is_swbp_insn(&old_opcode); 274ed6f6a50SOleg Nesterov 275ed6f6a50SOleg Nesterov if (is_swbp_insn(new_opcode)) { 276ed6f6a50SOleg Nesterov if (is_swbp) /* register: already installed? */ 277ed6f6a50SOleg Nesterov return 0; 278ed6f6a50SOleg Nesterov } else { 279ed6f6a50SOleg Nesterov if (!is_swbp) /* unregister: was it changed by us? */ 280076a365bSOleg Nesterov return 0; 281ed6f6a50SOleg Nesterov } 282ed6f6a50SOleg Nesterov 283ed6f6a50SOleg Nesterov return 1; 284ed6f6a50SOleg Nesterov } 285ed6f6a50SOleg Nesterov 2861cc33161SRavi Bangoria static struct delayed_uprobe * 2871cc33161SRavi Bangoria delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm) 2881cc33161SRavi Bangoria { 2891cc33161SRavi Bangoria struct delayed_uprobe *du; 2901cc33161SRavi Bangoria 2911cc33161SRavi Bangoria list_for_each_entry(du, &delayed_uprobe_list, list) 2921cc33161SRavi Bangoria if (du->uprobe == uprobe && du->mm == mm) 2931cc33161SRavi Bangoria return du; 2941cc33161SRavi Bangoria return NULL; 2951cc33161SRavi Bangoria } 2961cc33161SRavi Bangoria 2971cc33161SRavi Bangoria static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm) 2981cc33161SRavi Bangoria { 2991cc33161SRavi Bangoria struct delayed_uprobe *du; 3001cc33161SRavi Bangoria 3011cc33161SRavi Bangoria if (delayed_uprobe_check(uprobe, mm)) 3021cc33161SRavi Bangoria return 0; 3031cc33161SRavi Bangoria 3041cc33161SRavi Bangoria du = kzalloc(sizeof(*du), GFP_KERNEL); 3051cc33161SRavi Bangoria if (!du) 3061cc33161SRavi Bangoria return -ENOMEM; 3071cc33161SRavi Bangoria 3081cc33161SRavi Bangoria du->uprobe = uprobe; 3091cc33161SRavi Bangoria du->mm = mm; 3101cc33161SRavi Bangoria list_add(&du->list, &delayed_uprobe_list); 3111cc33161SRavi Bangoria return 0; 3121cc33161SRavi Bangoria } 3131cc33161SRavi Bangoria 3141cc33161SRavi Bangoria static void delayed_uprobe_delete(struct delayed_uprobe *du) 3151cc33161SRavi Bangoria { 3161cc33161SRavi Bangoria if (WARN_ON(!du)) 3171cc33161SRavi Bangoria return; 3181cc33161SRavi Bangoria list_del(&du->list); 3191cc33161SRavi Bangoria kfree(du); 3201cc33161SRavi Bangoria } 3211cc33161SRavi Bangoria 3221cc33161SRavi Bangoria static void delayed_uprobe_remove(struct uprobe *uprobe, struct mm_struct *mm) 3231cc33161SRavi Bangoria { 3241cc33161SRavi Bangoria struct list_head *pos, *q; 3251cc33161SRavi Bangoria struct delayed_uprobe *du; 3261cc33161SRavi Bangoria 3271cc33161SRavi Bangoria if (!uprobe && !mm) 3281cc33161SRavi Bangoria return; 3291cc33161SRavi Bangoria 3301cc33161SRavi Bangoria list_for_each_safe(pos, q, &delayed_uprobe_list) { 3311cc33161SRavi Bangoria du = list_entry(pos, struct delayed_uprobe, list); 3321cc33161SRavi Bangoria 3331cc33161SRavi Bangoria if (uprobe && du->uprobe != uprobe) 3341cc33161SRavi Bangoria continue; 3351cc33161SRavi Bangoria if (mm && du->mm != mm) 3361cc33161SRavi Bangoria continue; 3371cc33161SRavi Bangoria 3381cc33161SRavi Bangoria delayed_uprobe_delete(du); 3391cc33161SRavi Bangoria } 3401cc33161SRavi Bangoria } 3411cc33161SRavi Bangoria 3421cc33161SRavi Bangoria static bool valid_ref_ctr_vma(struct uprobe *uprobe, 3431cc33161SRavi Bangoria struct vm_area_struct *vma) 3441cc33161SRavi Bangoria { 3451cc33161SRavi Bangoria unsigned long vaddr = offset_to_vaddr(vma, uprobe->ref_ctr_offset); 3461cc33161SRavi Bangoria 3471cc33161SRavi Bangoria return uprobe->ref_ctr_offset && 3481cc33161SRavi Bangoria vma->vm_file && 3491cc33161SRavi Bangoria file_inode(vma->vm_file) == uprobe->inode && 3501cc33161SRavi Bangoria (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && 3511cc33161SRavi Bangoria vma->vm_start <= vaddr && 3521cc33161SRavi Bangoria vma->vm_end > vaddr; 3531cc33161SRavi Bangoria } 3541cc33161SRavi Bangoria 3551cc33161SRavi Bangoria static struct vm_area_struct * 3561cc33161SRavi Bangoria find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm) 3571cc33161SRavi Bangoria { 3581cc33161SRavi Bangoria struct vm_area_struct *tmp; 3591cc33161SRavi Bangoria 3601cc33161SRavi Bangoria for (tmp = mm->mmap; tmp; tmp = tmp->vm_next) 3611cc33161SRavi Bangoria if (valid_ref_ctr_vma(uprobe, tmp)) 3621cc33161SRavi Bangoria return tmp; 3631cc33161SRavi Bangoria 3641cc33161SRavi Bangoria return NULL; 3651cc33161SRavi Bangoria } 3661cc33161SRavi Bangoria 3671cc33161SRavi Bangoria static int 3681cc33161SRavi Bangoria __update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d) 3691cc33161SRavi Bangoria { 3701cc33161SRavi Bangoria void *kaddr; 3711cc33161SRavi Bangoria struct page *page; 3721cc33161SRavi Bangoria struct vm_area_struct *vma; 3731cc33161SRavi Bangoria int ret; 3741cc33161SRavi Bangoria short *ptr; 3751cc33161SRavi Bangoria 3761cc33161SRavi Bangoria if (!vaddr || !d) 3771cc33161SRavi Bangoria return -EINVAL; 3781cc33161SRavi Bangoria 37964019a2eSPeter Xu ret = get_user_pages_remote(mm, vaddr, 1, 3801cc33161SRavi Bangoria FOLL_WRITE, &page, &vma, NULL); 3811cc33161SRavi Bangoria if (unlikely(ret <= 0)) { 3821cc33161SRavi Bangoria /* 3831cc33161SRavi Bangoria * We are asking for 1 page. If get_user_pages_remote() fails, 3841cc33161SRavi Bangoria * it may return 0, in that case we have to return error. 3851cc33161SRavi Bangoria */ 3861cc33161SRavi Bangoria return ret == 0 ? -EBUSY : ret; 3871cc33161SRavi Bangoria } 3881cc33161SRavi Bangoria 3891cc33161SRavi Bangoria kaddr = kmap_atomic(page); 3901cc33161SRavi Bangoria ptr = kaddr + (vaddr & ~PAGE_MASK); 3911cc33161SRavi Bangoria 3921cc33161SRavi Bangoria if (unlikely(*ptr + d < 0)) { 3931cc33161SRavi Bangoria pr_warn("ref_ctr going negative. vaddr: 0x%lx, " 3941cc33161SRavi Bangoria "curr val: %d, delta: %d\n", vaddr, *ptr, d); 3951cc33161SRavi Bangoria ret = -EINVAL; 3961cc33161SRavi Bangoria goto out; 3971cc33161SRavi Bangoria } 3981cc33161SRavi Bangoria 3991cc33161SRavi Bangoria *ptr += d; 4001cc33161SRavi Bangoria ret = 0; 4011cc33161SRavi Bangoria out: 4021cc33161SRavi Bangoria kunmap_atomic(kaddr); 4031cc33161SRavi Bangoria put_page(page); 4041cc33161SRavi Bangoria return ret; 4051cc33161SRavi Bangoria } 4061cc33161SRavi Bangoria 4071cc33161SRavi Bangoria static void update_ref_ctr_warn(struct uprobe *uprobe, 4081cc33161SRavi Bangoria struct mm_struct *mm, short d) 4091cc33161SRavi Bangoria { 4101cc33161SRavi Bangoria pr_warn("ref_ctr %s failed for inode: 0x%lx offset: " 4111cc33161SRavi Bangoria "0x%llx ref_ctr_offset: 0x%llx of mm: 0x%pK\n", 4121cc33161SRavi Bangoria d > 0 ? "increment" : "decrement", uprobe->inode->i_ino, 4131cc33161SRavi Bangoria (unsigned long long) uprobe->offset, 4141cc33161SRavi Bangoria (unsigned long long) uprobe->ref_ctr_offset, mm); 4151cc33161SRavi Bangoria } 4161cc33161SRavi Bangoria 4171cc33161SRavi Bangoria static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm, 4181cc33161SRavi Bangoria short d) 4191cc33161SRavi Bangoria { 4201cc33161SRavi Bangoria struct vm_area_struct *rc_vma; 4211cc33161SRavi Bangoria unsigned long rc_vaddr; 4221cc33161SRavi Bangoria int ret = 0; 4231cc33161SRavi Bangoria 4241cc33161SRavi Bangoria rc_vma = find_ref_ctr_vma(uprobe, mm); 4251cc33161SRavi Bangoria 4261cc33161SRavi Bangoria if (rc_vma) { 4271cc33161SRavi Bangoria rc_vaddr = offset_to_vaddr(rc_vma, uprobe->ref_ctr_offset); 4281cc33161SRavi Bangoria ret = __update_ref_ctr(mm, rc_vaddr, d); 4291cc33161SRavi Bangoria if (ret) 4301cc33161SRavi Bangoria update_ref_ctr_warn(uprobe, mm, d); 4311cc33161SRavi Bangoria 4321cc33161SRavi Bangoria if (d > 0) 4331cc33161SRavi Bangoria return ret; 4341cc33161SRavi Bangoria } 4351cc33161SRavi Bangoria 4361cc33161SRavi Bangoria mutex_lock(&delayed_uprobe_lock); 4371cc33161SRavi Bangoria if (d > 0) 4381cc33161SRavi Bangoria ret = delayed_uprobe_add(uprobe, mm); 4391cc33161SRavi Bangoria else 4401cc33161SRavi Bangoria delayed_uprobe_remove(uprobe, mm); 4411cc33161SRavi Bangoria mutex_unlock(&delayed_uprobe_lock); 4421cc33161SRavi Bangoria 4431cc33161SRavi Bangoria return ret; 4441cc33161SRavi Bangoria } 4451cc33161SRavi Bangoria 446a5f4374aSIngo Molnar /* 447a5f4374aSIngo Molnar * NOTE: 448a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 449a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 450a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 4510908ad6eSAnanth N Mavinakayanahalli * supported by that architecture then we need to modify is_trap_at_addr and 452f72d41faSOleg Nesterov * uprobe_write_opcode accordingly. This would never be a problem for archs 453f72d41faSOleg Nesterov * that have fixed length instructions. 45429dedee0SOleg Nesterov * 455f72d41faSOleg Nesterov * uprobe_write_opcode - write the opcode at a given virtual address. 456a5f4374aSIngo Molnar * @mm: the probed process address space. 457a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 458a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 459a5f4374aSIngo Molnar * 460c1e8d7c6SMichel Lespinasse * Called with mm->mmap_lock held for write. 461a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 462a5f4374aSIngo Molnar */ 4636d43743eSRavi Bangoria int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, 4646d43743eSRavi Bangoria unsigned long vaddr, uprobe_opcode_t opcode) 465a5f4374aSIngo Molnar { 4661cc33161SRavi Bangoria struct uprobe *uprobe; 467a5f4374aSIngo Molnar struct page *old_page, *new_page; 468a5f4374aSIngo Molnar struct vm_area_struct *vma; 4691cc33161SRavi Bangoria int ret, is_register, ref_ctr_updated = 0; 470f385cb85SSong Liu bool orig_page_huge = false; 471aa5de305SSong Liu unsigned int gup_flags = FOLL_FORCE; 4721cc33161SRavi Bangoria 4731cc33161SRavi Bangoria is_register = is_swbp_insn(&opcode); 4741cc33161SRavi Bangoria uprobe = container_of(auprobe, struct uprobe, arch); 475f403072cSOleg Nesterov 4765323ce71SOleg Nesterov retry: 477aa5de305SSong Liu if (is_register) 478aa5de305SSong Liu gup_flags |= FOLL_SPLIT_PMD; 479a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 48064019a2eSPeter Xu ret = get_user_pages_remote(mm, vaddr, 1, gup_flags, 481aa5de305SSong Liu &old_page, &vma, NULL); 482a5f4374aSIngo Molnar if (ret <= 0) 483a5f4374aSIngo Molnar return ret; 484a5f4374aSIngo Molnar 485ed6f6a50SOleg Nesterov ret = verify_opcode(old_page, vaddr, &opcode); 486ed6f6a50SOleg Nesterov if (ret <= 0) 487ed6f6a50SOleg Nesterov goto put_old; 488ed6f6a50SOleg Nesterov 489aa5de305SSong Liu if (WARN(!is_register && PageCompound(old_page), 490aa5de305SSong Liu "uprobe unregister should never work on compound page\n")) { 491aa5de305SSong Liu ret = -EINVAL; 492aa5de305SSong Liu goto put_old; 493aa5de305SSong Liu } 494aa5de305SSong Liu 4951cc33161SRavi Bangoria /* We are going to replace instruction, update ref_ctr. */ 4961cc33161SRavi Bangoria if (!ref_ctr_updated && uprobe->ref_ctr_offset) { 4971cc33161SRavi Bangoria ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1); 4981cc33161SRavi Bangoria if (ret) 4991cc33161SRavi Bangoria goto put_old; 5001cc33161SRavi Bangoria 5011cc33161SRavi Bangoria ref_ctr_updated = 1; 5021cc33161SRavi Bangoria } 5031cc33161SRavi Bangoria 504fb4fb04fSSong Liu ret = 0; 505fb4fb04fSSong Liu if (!is_register && !PageAnon(old_page)) 506fb4fb04fSSong Liu goto put_old; 507fb4fb04fSSong Liu 50829dedee0SOleg Nesterov ret = anon_vma_prepare(vma); 50929dedee0SOleg Nesterov if (ret) 51029dedee0SOleg Nesterov goto put_old; 51129dedee0SOleg Nesterov 512a5f4374aSIngo Molnar ret = -ENOMEM; 513a5f4374aSIngo Molnar new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); 514a5f4374aSIngo Molnar if (!new_page) 5159f92448cSOleg Nesterov goto put_old; 516a5f4374aSIngo Molnar 51729dedee0SOleg Nesterov __SetPageUptodate(new_page); 5183f47107cSOleg Nesterov copy_highpage(new_page, old_page); 5193f47107cSOleg Nesterov copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 520a5f4374aSIngo Molnar 521fb4fb04fSSong Liu if (!is_register) { 522fb4fb04fSSong Liu struct page *orig_page; 523fb4fb04fSSong Liu pgoff_t index; 524fb4fb04fSSong Liu 525fb4fb04fSSong Liu VM_BUG_ON_PAGE(!PageAnon(old_page), old_page); 526fb4fb04fSSong Liu 527fb4fb04fSSong Liu index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT; 528fb4fb04fSSong Liu orig_page = find_get_page(vma->vm_file->f_inode->i_mapping, 529fb4fb04fSSong Liu index); 530fb4fb04fSSong Liu 531fb4fb04fSSong Liu if (orig_page) { 532fb4fb04fSSong Liu if (PageUptodate(orig_page) && 533fb4fb04fSSong Liu pages_identical(new_page, orig_page)) { 534fb4fb04fSSong Liu /* let go new_page */ 535fb4fb04fSSong Liu put_page(new_page); 536fb4fb04fSSong Liu new_page = NULL; 537f385cb85SSong Liu 538f385cb85SSong Liu if (PageCompound(orig_page)) 539f385cb85SSong Liu orig_page_huge = true; 540fb4fb04fSSong Liu } 541fb4fb04fSSong Liu put_page(orig_page); 542fb4fb04fSSong Liu } 543fb4fb04fSSong Liu } 544fb4fb04fSSong Liu 545c517ee74SOleg Nesterov ret = __replace_page(vma, vaddr, old_page, new_page); 546fb4fb04fSSong Liu if (new_page) 54709cbfeafSKirill A. Shutemov put_page(new_page); 5489f92448cSOleg Nesterov put_old: 549a5f4374aSIngo Molnar put_page(old_page); 550a5f4374aSIngo Molnar 5515323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 5525323ce71SOleg Nesterov goto retry; 5531cc33161SRavi Bangoria 5541cc33161SRavi Bangoria /* Revert back reference counter if instruction update failed. */ 5551cc33161SRavi Bangoria if (ret && is_register && ref_ctr_updated) 5561cc33161SRavi Bangoria update_ref_ctr(uprobe, mm, -1); 5571cc33161SRavi Bangoria 558f385cb85SSong Liu /* try collapse pmd for compound page */ 559f385cb85SSong Liu if (!ret && orig_page_huge) 560f385cb85SSong Liu collapse_pte_mapped_thp(mm, vaddr); 561f385cb85SSong Liu 562a5f4374aSIngo Molnar return ret; 563a5f4374aSIngo Molnar } 564a5f4374aSIngo Molnar 565a5f4374aSIngo Molnar /** 5665cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 567e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 568a5f4374aSIngo Molnar * @mm: the probed process address space. 569a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 570a5f4374aSIngo Molnar * 571a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 572a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 573a5f4374aSIngo Molnar */ 5745cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 575a5f4374aSIngo Molnar { 5766d43743eSRavi Bangoria return uprobe_write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); 577a5f4374aSIngo Molnar } 578a5f4374aSIngo Molnar 579a5f4374aSIngo Molnar /** 580a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 581a5f4374aSIngo Molnar * @mm: the probed process address space. 582e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 583a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 584a5f4374aSIngo Molnar * 585a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 586a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 587a5f4374aSIngo Molnar */ 588a5f4374aSIngo Molnar int __weak 589ded86e7cSOleg Nesterov set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 590a5f4374aSIngo Molnar { 5916d43743eSRavi Bangoria return uprobe_write_opcode(auprobe, mm, vaddr, 5926d43743eSRavi Bangoria *(uprobe_opcode_t *)&auprobe->insn); 593a5f4374aSIngo Molnar } 594a5f4374aSIngo Molnar 595f231722aSOleg Nesterov static struct uprobe *get_uprobe(struct uprobe *uprobe) 596f231722aSOleg Nesterov { 597ce59b8e9SElena Reshetova refcount_inc(&uprobe->ref); 598f231722aSOleg Nesterov return uprobe; 599f231722aSOleg Nesterov } 600f231722aSOleg Nesterov 601f231722aSOleg Nesterov static void put_uprobe(struct uprobe *uprobe) 602f231722aSOleg Nesterov { 603ce59b8e9SElena Reshetova if (refcount_dec_and_test(&uprobe->ref)) { 6041cc33161SRavi Bangoria /* 6051cc33161SRavi Bangoria * If application munmap(exec_vma) before uprobe_unregister() 6061cc33161SRavi Bangoria * gets called, we don't get a chance to remove uprobe from 6071cc33161SRavi Bangoria * delayed_uprobe_list from remove_breakpoint(). Do it here. 6081cc33161SRavi Bangoria */ 6091aed58e6SRavi Bangoria mutex_lock(&delayed_uprobe_lock); 6101cc33161SRavi Bangoria delayed_uprobe_remove(uprobe, NULL); 6111aed58e6SRavi Bangoria mutex_unlock(&delayed_uprobe_lock); 612f231722aSOleg Nesterov kfree(uprobe); 613f231722aSOleg Nesterov } 6141cc33161SRavi Bangoria } 615f231722aSOleg Nesterov 616*a905e84eSPeter Zijlstra static __always_inline 617*a905e84eSPeter Zijlstra int uprobe_cmp(const struct inode *l_inode, const loff_t l_offset, 618*a905e84eSPeter Zijlstra const struct uprobe *r) 619a5f4374aSIngo Molnar { 620*a905e84eSPeter Zijlstra if (l_inode < r->inode) 621a5f4374aSIngo Molnar return -1; 622a5f4374aSIngo Molnar 623*a905e84eSPeter Zijlstra if (l_inode > r->inode) 624a5f4374aSIngo Molnar return 1; 625a5f4374aSIngo Molnar 626*a905e84eSPeter Zijlstra if (l_offset < r->offset) 627a5f4374aSIngo Molnar return -1; 628a5f4374aSIngo Molnar 629*a905e84eSPeter Zijlstra if (l_offset > r->offset) 630a5f4374aSIngo Molnar return 1; 631a5f4374aSIngo Molnar 632a5f4374aSIngo Molnar return 0; 633a5f4374aSIngo Molnar } 634a5f4374aSIngo Molnar 635*a905e84eSPeter Zijlstra #define __node_2_uprobe(node) \ 636*a905e84eSPeter Zijlstra rb_entry((node), struct uprobe, rb_node) 637*a905e84eSPeter Zijlstra 638*a905e84eSPeter Zijlstra struct __uprobe_key { 639*a905e84eSPeter Zijlstra struct inode *inode; 640*a905e84eSPeter Zijlstra loff_t offset; 641*a905e84eSPeter Zijlstra }; 642*a905e84eSPeter Zijlstra 643*a905e84eSPeter Zijlstra static inline int __uprobe_cmp_key(const void *key, const struct rb_node *b) 644*a905e84eSPeter Zijlstra { 645*a905e84eSPeter Zijlstra const struct __uprobe_key *a = key; 646*a905e84eSPeter Zijlstra return uprobe_cmp(a->inode, a->offset, __node_2_uprobe(b)); 647*a905e84eSPeter Zijlstra } 648*a905e84eSPeter Zijlstra 649*a905e84eSPeter Zijlstra static inline int __uprobe_cmp(struct rb_node *a, const struct rb_node *b) 650*a905e84eSPeter Zijlstra { 651*a905e84eSPeter Zijlstra struct uprobe *u = __node_2_uprobe(a); 652*a905e84eSPeter Zijlstra return uprobe_cmp(u->inode, u->offset, __node_2_uprobe(b)); 653*a905e84eSPeter Zijlstra } 654*a905e84eSPeter Zijlstra 655a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 656a5f4374aSIngo Molnar { 657*a905e84eSPeter Zijlstra struct __uprobe_key key = { 658*a905e84eSPeter Zijlstra .inode = inode, 659*a905e84eSPeter Zijlstra .offset = offset, 660*a905e84eSPeter Zijlstra }; 661*a905e84eSPeter Zijlstra struct rb_node *node = rb_find(&key, &uprobes_tree, __uprobe_cmp_key); 662a5f4374aSIngo Molnar 663*a905e84eSPeter Zijlstra if (node) 664*a905e84eSPeter Zijlstra return __node_2_uprobe(node); 665a5f4374aSIngo Molnar 666a5f4374aSIngo Molnar return NULL; 667a5f4374aSIngo Molnar } 668a5f4374aSIngo Molnar 669a5f4374aSIngo Molnar /* 670a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 671a5f4374aSIngo Molnar * Acquires uprobes_treelock 672a5f4374aSIngo Molnar */ 673a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 674a5f4374aSIngo Molnar { 675a5f4374aSIngo Molnar struct uprobe *uprobe; 676a5f4374aSIngo Molnar 6776f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 678a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 6796f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 680a5f4374aSIngo Molnar 681a5f4374aSIngo Molnar return uprobe; 682a5f4374aSIngo Molnar } 683a5f4374aSIngo Molnar 684a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 685a5f4374aSIngo Molnar { 686*a905e84eSPeter Zijlstra struct rb_node *node; 687a5f4374aSIngo Molnar 688*a905e84eSPeter Zijlstra node = rb_find_add(&uprobe->rb_node, &uprobes_tree, __uprobe_cmp); 689*a905e84eSPeter Zijlstra if (node) 690*a905e84eSPeter Zijlstra return get_uprobe(__node_2_uprobe(node)); 691a5f4374aSIngo Molnar 692a5f4374aSIngo Molnar /* get access + creation ref */ 693ce59b8e9SElena Reshetova refcount_set(&uprobe->ref, 2); 694*a905e84eSPeter Zijlstra return NULL; 695a5f4374aSIngo Molnar } 696a5f4374aSIngo Molnar 697a5f4374aSIngo Molnar /* 698a5f4374aSIngo Molnar * Acquire uprobes_treelock. 699a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 700a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 701a5f4374aSIngo Molnar * 702a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 703a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 704a5f4374aSIngo Molnar */ 705a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 706a5f4374aSIngo Molnar { 707a5f4374aSIngo Molnar struct uprobe *u; 708a5f4374aSIngo Molnar 7096f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 710a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 7116f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 712a5f4374aSIngo Molnar 713a5f4374aSIngo Molnar return u; 714a5f4374aSIngo Molnar } 715a5f4374aSIngo Molnar 71622bad382SRavi Bangoria static void 71722bad382SRavi Bangoria ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe) 71822bad382SRavi Bangoria { 71922bad382SRavi Bangoria pr_warn("ref_ctr_offset mismatch. inode: 0x%lx offset: 0x%llx " 72022bad382SRavi Bangoria "ref_ctr_offset(old): 0x%llx ref_ctr_offset(new): 0x%llx\n", 72122bad382SRavi Bangoria uprobe->inode->i_ino, (unsigned long long) uprobe->offset, 72222bad382SRavi Bangoria (unsigned long long) cur_uprobe->ref_ctr_offset, 72322bad382SRavi Bangoria (unsigned long long) uprobe->ref_ctr_offset); 72422bad382SRavi Bangoria } 72522bad382SRavi Bangoria 7261cc33161SRavi Bangoria static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, 7271cc33161SRavi Bangoria loff_t ref_ctr_offset) 728a5f4374aSIngo Molnar { 729a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 730a5f4374aSIngo Molnar 731a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 732a5f4374aSIngo Molnar if (!uprobe) 733a5f4374aSIngo Molnar return NULL; 734a5f4374aSIngo Molnar 73561f94203SSong Liu uprobe->inode = inode; 736a5f4374aSIngo Molnar uprobe->offset = offset; 7371cc33161SRavi Bangoria uprobe->ref_ctr_offset = ref_ctr_offset; 738e591c8d7SOleg Nesterov init_rwsem(&uprobe->register_rwsem); 739a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 740a5f4374aSIngo Molnar 741a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 742a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 743a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 744a5f4374aSIngo Molnar if (cur_uprobe) { 74522bad382SRavi Bangoria if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) { 74622bad382SRavi Bangoria ref_ctr_mismatch_warn(cur_uprobe, uprobe); 74722bad382SRavi Bangoria put_uprobe(cur_uprobe); 74822bad382SRavi Bangoria kfree(uprobe); 74922bad382SRavi Bangoria return ERR_PTR(-EINVAL); 75022bad382SRavi Bangoria } 751a5f4374aSIngo Molnar kfree(uprobe); 752a5f4374aSIngo Molnar uprobe = cur_uprobe; 753a5f4374aSIngo Molnar } 754a5f4374aSIngo Molnar 755a5f4374aSIngo Molnar return uprobe; 756a5f4374aSIngo Molnar } 757a5f4374aSIngo Molnar 7589a98e03cSOleg Nesterov static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 759a5f4374aSIngo Molnar { 760a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 761e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 762e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 763a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 764a5f4374aSIngo Molnar } 765a5f4374aSIngo Molnar 766a5f4374aSIngo Molnar /* 767e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 768e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 769a5f4374aSIngo Molnar * or return false. 770a5f4374aSIngo Molnar */ 771e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 772a5f4374aSIngo Molnar { 773a5f4374aSIngo Molnar struct uprobe_consumer **con; 774a5f4374aSIngo Molnar bool ret = false; 775a5f4374aSIngo Molnar 776a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 777a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 778e3343e6aSSrikar Dronamraju if (*con == uc) { 779e3343e6aSSrikar Dronamraju *con = uc->next; 780a5f4374aSIngo Molnar ret = true; 781a5f4374aSIngo Molnar break; 782a5f4374aSIngo Molnar } 783a5f4374aSIngo Molnar } 784a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 785a5f4374aSIngo Molnar 786a5f4374aSIngo Molnar return ret; 787a5f4374aSIngo Molnar } 788a5f4374aSIngo Molnar 7892ded0980SOleg Nesterov static int __copy_insn(struct address_space *mapping, struct file *filp, 7902ded0980SOleg Nesterov void *insn, int nbytes, loff_t offset) 791a5f4374aSIngo Molnar { 792a5f4374aSIngo Molnar struct page *page; 793a5f4374aSIngo Molnar /* 79440814f68SOleg Nesterov * Ensure that the page that has the original instruction is populated 79540814f68SOleg Nesterov * and in page-cache. If ->readpage == NULL it must be shmem_mapping(), 79640814f68SOleg Nesterov * see uprobe_register(). 797a5f4374aSIngo Molnar */ 79840814f68SOleg Nesterov if (mapping->a_ops->readpage) 79909cbfeafSKirill A. Shutemov page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp); 80040814f68SOleg Nesterov else 80109cbfeafSKirill A. Shutemov page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); 802a5f4374aSIngo Molnar if (IS_ERR(page)) 803a5f4374aSIngo Molnar return PTR_ERR(page); 804a5f4374aSIngo Molnar 8052edb7b55SOleg Nesterov copy_from_page(page, offset, insn, nbytes); 80609cbfeafSKirill A. Shutemov put_page(page); 807a5f4374aSIngo Molnar 808a5f4374aSIngo Molnar return 0; 809a5f4374aSIngo Molnar } 810a5f4374aSIngo Molnar 811d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 812a5f4374aSIngo Molnar { 8132ded0980SOleg Nesterov struct address_space *mapping = uprobe->inode->i_mapping; 8142ded0980SOleg Nesterov loff_t offs = uprobe->offset; 815803200e2SOleg Nesterov void *insn = &uprobe->arch.insn; 816803200e2SOleg Nesterov int size = sizeof(uprobe->arch.insn); 8172ded0980SOleg Nesterov int len, err = -EIO; 818a5f4374aSIngo Molnar 8192ded0980SOleg Nesterov /* Copy only available bytes, -EIO if nothing was read */ 8202ded0980SOleg Nesterov do { 8212ded0980SOleg Nesterov if (offs >= i_size_read(uprobe->inode)) 8222ded0980SOleg Nesterov break; 823a5f4374aSIngo Molnar 8242ded0980SOleg Nesterov len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); 8252ded0980SOleg Nesterov err = __copy_insn(mapping, filp, insn, len, offs); 826fc36f595SOleg Nesterov if (err) 8272ded0980SOleg Nesterov break; 8282ded0980SOleg Nesterov 8292ded0980SOleg Nesterov insn += len; 8302ded0980SOleg Nesterov offs += len; 8312ded0980SOleg Nesterov size -= len; 8322ded0980SOleg Nesterov } while (size); 8332ded0980SOleg Nesterov 834fc36f595SOleg Nesterov return err; 835a5f4374aSIngo Molnar } 836a5f4374aSIngo Molnar 837cb9a19feSOleg Nesterov static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 838cb9a19feSOleg Nesterov struct mm_struct *mm, unsigned long vaddr) 839cb9a19feSOleg Nesterov { 840cb9a19feSOleg Nesterov int ret = 0; 841cb9a19feSOleg Nesterov 84271434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 843cb9a19feSOleg Nesterov return ret; 844cb9a19feSOleg Nesterov 845d4d3ccc6SOleg Nesterov /* TODO: move this into _register, until then we abuse this sem. */ 846d4d3ccc6SOleg Nesterov down_write(&uprobe->consumer_rwsem); 84771434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 8484710f05fSOleg Nesterov goto out; 8494710f05fSOleg Nesterov 850cb9a19feSOleg Nesterov ret = copy_insn(uprobe, file); 851cb9a19feSOleg Nesterov if (ret) 852cb9a19feSOleg Nesterov goto out; 853cb9a19feSOleg Nesterov 854cb9a19feSOleg Nesterov ret = -ENOTSUPP; 855803200e2SOleg Nesterov if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) 856cb9a19feSOleg Nesterov goto out; 857cb9a19feSOleg Nesterov 858cb9a19feSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 859cb9a19feSOleg Nesterov if (ret) 860cb9a19feSOleg Nesterov goto out; 861cb9a19feSOleg Nesterov 86209d3f015SAndrea Parri smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */ 86371434f2fSOleg Nesterov set_bit(UPROBE_COPY_INSN, &uprobe->flags); 864cb9a19feSOleg Nesterov 865cb9a19feSOleg Nesterov out: 866d4d3ccc6SOleg Nesterov up_write(&uprobe->consumer_rwsem); 8674710f05fSOleg Nesterov 868cb9a19feSOleg Nesterov return ret; 869cb9a19feSOleg Nesterov } 870cb9a19feSOleg Nesterov 8718a7f2fa0SOleg Nesterov static inline bool consumer_filter(struct uprobe_consumer *uc, 8728a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 873806a98bdSOleg Nesterov { 8748a7f2fa0SOleg Nesterov return !uc->filter || uc->filter(uc, ctx, mm); 875806a98bdSOleg Nesterov } 876806a98bdSOleg Nesterov 8778a7f2fa0SOleg Nesterov static bool filter_chain(struct uprobe *uprobe, 8788a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 87963633cbfSOleg Nesterov { 8801ff6fee5SOleg Nesterov struct uprobe_consumer *uc; 8811ff6fee5SOleg Nesterov bool ret = false; 8821ff6fee5SOleg Nesterov 8831ff6fee5SOleg Nesterov down_read(&uprobe->consumer_rwsem); 8841ff6fee5SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 8858a7f2fa0SOleg Nesterov ret = consumer_filter(uc, ctx, mm); 8861ff6fee5SOleg Nesterov if (ret) 8871ff6fee5SOleg Nesterov break; 8881ff6fee5SOleg Nesterov } 8891ff6fee5SOleg Nesterov up_read(&uprobe->consumer_rwsem); 8901ff6fee5SOleg Nesterov 8911ff6fee5SOleg Nesterov return ret; 89263633cbfSOleg Nesterov } 89363633cbfSOleg Nesterov 894e3343e6aSSrikar Dronamraju static int 895e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 896816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 897a5f4374aSIngo Molnar { 898f8ac4ec9SOleg Nesterov bool first_uprobe; 899a5f4374aSIngo Molnar int ret; 900a5f4374aSIngo Molnar 901cb9a19feSOleg Nesterov ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); 902a5f4374aSIngo Molnar if (ret) 903a5f4374aSIngo Molnar return ret; 904a5f4374aSIngo Molnar 905f8ac4ec9SOleg Nesterov /* 906f8ac4ec9SOleg Nesterov * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), 907f8ac4ec9SOleg Nesterov * the task can hit this breakpoint right after __replace_page(). 908f8ac4ec9SOleg Nesterov */ 909f8ac4ec9SOleg Nesterov first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); 910f8ac4ec9SOleg Nesterov if (first_uprobe) 911f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &mm->flags); 912f8ac4ec9SOleg Nesterov 913816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 9149f68f672SOleg Nesterov if (!ret) 9159f68f672SOleg Nesterov clear_bit(MMF_RECALC_UPROBES, &mm->flags); 9169f68f672SOleg Nesterov else if (first_uprobe) 917f8ac4ec9SOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 918a5f4374aSIngo Molnar 919a5f4374aSIngo Molnar return ret; 920a5f4374aSIngo Molnar } 921a5f4374aSIngo Molnar 922076a365bSOleg Nesterov static int 923816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 924a5f4374aSIngo Molnar { 9259f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &mm->flags); 926076a365bSOleg Nesterov return set_orig_insn(&uprobe->arch, mm, vaddr); 927a5f4374aSIngo Molnar } 928a5f4374aSIngo Molnar 92906b7bcd8SOleg Nesterov static inline bool uprobe_is_active(struct uprobe *uprobe) 93006b7bcd8SOleg Nesterov { 93106b7bcd8SOleg Nesterov return !RB_EMPTY_NODE(&uprobe->rb_node); 93206b7bcd8SOleg Nesterov } 9330326f5a9SSrikar Dronamraju /* 934778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 935778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 936778b032dSOleg Nesterov * See find_active_uprobe(). 9370326f5a9SSrikar Dronamraju */ 938a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 939a5f4374aSIngo Molnar { 94006b7bcd8SOleg Nesterov if (WARN_ON(!uprobe_is_active(uprobe))) 94106b7bcd8SOleg Nesterov return; 94206b7bcd8SOleg Nesterov 9436f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 944a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 9456f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 94606b7bcd8SOleg Nesterov RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ 947a5f4374aSIngo Molnar put_uprobe(uprobe); 948a5f4374aSIngo Molnar } 949a5f4374aSIngo Molnar 95026872090SOleg Nesterov struct map_info { 95126872090SOleg Nesterov struct map_info *next; 95226872090SOleg Nesterov struct mm_struct *mm; 953816c03fbSOleg Nesterov unsigned long vaddr; 95426872090SOleg Nesterov }; 95526872090SOleg Nesterov 95626872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 957a5f4374aSIngo Molnar { 95826872090SOleg Nesterov struct map_info *next = info->next; 95926872090SOleg Nesterov kfree(info); 96026872090SOleg Nesterov return next; 96126872090SOleg Nesterov } 96226872090SOleg Nesterov 96326872090SOleg Nesterov static struct map_info * 96426872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 96526872090SOleg Nesterov { 96626872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 967a5f4374aSIngo Molnar struct vm_area_struct *vma; 96826872090SOleg Nesterov struct map_info *curr = NULL; 96926872090SOleg Nesterov struct map_info *prev = NULL; 97026872090SOleg Nesterov struct map_info *info; 97126872090SOleg Nesterov int more = 0; 972a5f4374aSIngo Molnar 97326872090SOleg Nesterov again: 9744a23717aSDavidlohr Bueso i_mmap_lock_read(mapping); 9756b2dbba8SMichel Lespinasse vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { 976a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 977a5f4374aSIngo Molnar continue; 978a5f4374aSIngo Molnar 9797a5bfb66SOleg Nesterov if (!prev && !more) { 9807a5bfb66SOleg Nesterov /* 981c8c06efaSDavidlohr Bueso * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through 9827a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 9837a5bfb66SOleg Nesterov */ 9847a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 9857a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 9867a5bfb66SOleg Nesterov if (prev) 9877a5bfb66SOleg Nesterov prev->next = NULL; 9887a5bfb66SOleg Nesterov } 98926872090SOleg Nesterov if (!prev) { 99026872090SOleg Nesterov more++; 99126872090SOleg Nesterov continue; 992a5f4374aSIngo Molnar } 993a5f4374aSIngo Molnar 994388f7934SVegard Nossum if (!mmget_not_zero(vma->vm_mm)) 99526872090SOleg Nesterov continue; 996a5f4374aSIngo Molnar 99726872090SOleg Nesterov info = prev; 99826872090SOleg Nesterov prev = prev->next; 99926872090SOleg Nesterov info->next = curr; 100026872090SOleg Nesterov curr = info; 100126872090SOleg Nesterov 100226872090SOleg Nesterov info->mm = vma->vm_mm; 100357683f72SOleg Nesterov info->vaddr = offset_to_vaddr(vma, offset); 1004a5f4374aSIngo Molnar } 10054a23717aSDavidlohr Bueso i_mmap_unlock_read(mapping); 1006a5f4374aSIngo Molnar 100726872090SOleg Nesterov if (!more) 100826872090SOleg Nesterov goto out; 1009a5f4374aSIngo Molnar 101026872090SOleg Nesterov prev = curr; 101126872090SOleg Nesterov while (curr) { 101226872090SOleg Nesterov mmput(curr->mm); 101326872090SOleg Nesterov curr = curr->next; 101426872090SOleg Nesterov } 101526872090SOleg Nesterov 101626872090SOleg Nesterov do { 101726872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 101826872090SOleg Nesterov if (!info) { 101926872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 102026872090SOleg Nesterov goto out; 102126872090SOleg Nesterov } 102226872090SOleg Nesterov info->next = prev; 102326872090SOleg Nesterov prev = info; 102426872090SOleg Nesterov } while (--more); 102526872090SOleg Nesterov 102626872090SOleg Nesterov goto again; 102726872090SOleg Nesterov out: 102826872090SOleg Nesterov while (prev) 102926872090SOleg Nesterov prev = free_map_info(prev); 103026872090SOleg Nesterov return curr; 1031a5f4374aSIngo Molnar } 1032a5f4374aSIngo Molnar 1033bdf8647cSOleg Nesterov static int 1034bdf8647cSOleg Nesterov register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) 1035a5f4374aSIngo Molnar { 1036bdf8647cSOleg Nesterov bool is_register = !!new; 103726872090SOleg Nesterov struct map_info *info; 103826872090SOleg Nesterov int err = 0; 103926872090SOleg Nesterov 104032cdba1eSOleg Nesterov percpu_down_write(&dup_mmap_sem); 104126872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 104226872090SOleg Nesterov uprobe->offset, is_register); 104332cdba1eSOleg Nesterov if (IS_ERR(info)) { 104432cdba1eSOleg Nesterov err = PTR_ERR(info); 104532cdba1eSOleg Nesterov goto out; 104632cdba1eSOleg Nesterov } 104726872090SOleg Nesterov 104826872090SOleg Nesterov while (info) { 104926872090SOleg Nesterov struct mm_struct *mm = info->mm; 1050a5f4374aSIngo Molnar struct vm_area_struct *vma; 1051a5f4374aSIngo Molnar 1052076a365bSOleg Nesterov if (err && is_register) 105326872090SOleg Nesterov goto free; 1054a5f4374aSIngo Molnar 1055d8ed45c5SMichel Lespinasse mmap_write_lock(mm); 1056f4d6dfe5SOleg Nesterov vma = find_vma(mm, info->vaddr); 1057f4d6dfe5SOleg Nesterov if (!vma || !valid_vma(vma, is_register) || 1058f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 105926872090SOleg Nesterov goto unlock; 106026872090SOleg Nesterov 1061f4d6dfe5SOleg Nesterov if (vma->vm_start > info->vaddr || 1062f4d6dfe5SOleg Nesterov vaddr_to_offset(vma, info->vaddr) != uprobe->offset) 106326872090SOleg Nesterov goto unlock; 1064a5f4374aSIngo Molnar 1065806a98bdSOleg Nesterov if (is_register) { 1066806a98bdSOleg Nesterov /* consult only the "caller", new consumer. */ 1067bdf8647cSOleg Nesterov if (consumer_filter(new, 10688a7f2fa0SOleg Nesterov UPROBE_FILTER_REGISTER, mm)) 106926872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 1070806a98bdSOleg Nesterov } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { 10718a7f2fa0SOleg Nesterov if (!filter_chain(uprobe, 10728a7f2fa0SOleg Nesterov UPROBE_FILTER_UNREGISTER, mm)) 1073076a365bSOleg Nesterov err |= remove_breakpoint(uprobe, mm, info->vaddr); 1074806a98bdSOleg Nesterov } 107578f74116SOleg Nesterov 107626872090SOleg Nesterov unlock: 1077d8ed45c5SMichel Lespinasse mmap_write_unlock(mm); 107826872090SOleg Nesterov free: 107926872090SOleg Nesterov mmput(mm); 108026872090SOleg Nesterov info = free_map_info(info); 1081a5f4374aSIngo Molnar } 108232cdba1eSOleg Nesterov out: 108332cdba1eSOleg Nesterov percpu_up_write(&dup_mmap_sem); 108426872090SOleg Nesterov return err; 1085a5f4374aSIngo Molnar } 1086a5f4374aSIngo Molnar 108738e967aeSRavi Bangoria static void 108838e967aeSRavi Bangoria __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) 1089a5f4374aSIngo Molnar { 109004aab9b2SOleg Nesterov int err; 1091a5f4374aSIngo Molnar 109206d07139SOleg Nesterov if (WARN_ON(!consumer_del(uprobe, uc))) 109304aab9b2SOleg Nesterov return; 109404aab9b2SOleg Nesterov 1095bdf8647cSOleg Nesterov err = register_for_each_vma(uprobe, NULL); 1096a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 1097bb929284SOleg Nesterov if (!uprobe->consumers && !err) 109804aab9b2SOleg Nesterov delete_uprobe(uprobe); 109904aab9b2SOleg Nesterov } 1100a5f4374aSIngo Molnar 1101a5f4374aSIngo Molnar /* 11027140ad38SLinus Torvalds * uprobe_unregister - unregister an already registered probe. 110338e967aeSRavi Bangoria * @inode: the file in which the probe has to be removed. 110438e967aeSRavi Bangoria * @offset: offset from the start of the file. 110538e967aeSRavi Bangoria * @uc: identify which probe if multiple probes are colocated. 110638e967aeSRavi Bangoria */ 110738e967aeSRavi Bangoria void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 110838e967aeSRavi Bangoria { 110938e967aeSRavi Bangoria struct uprobe *uprobe; 111038e967aeSRavi Bangoria 111138e967aeSRavi Bangoria uprobe = find_uprobe(inode, offset); 111238e967aeSRavi Bangoria if (WARN_ON(!uprobe)) 111338e967aeSRavi Bangoria return; 111438e967aeSRavi Bangoria 111538e967aeSRavi Bangoria down_write(&uprobe->register_rwsem); 111638e967aeSRavi Bangoria __uprobe_unregister(uprobe, uc); 111738e967aeSRavi Bangoria up_write(&uprobe->register_rwsem); 111838e967aeSRavi Bangoria put_uprobe(uprobe); 111938e967aeSRavi Bangoria } 112038e967aeSRavi Bangoria EXPORT_SYMBOL_GPL(uprobe_unregister); 112138e967aeSRavi Bangoria 112238e967aeSRavi Bangoria /* 112338e967aeSRavi Bangoria * __uprobe_register - register a probe 1124a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 1125a5f4374aSIngo Molnar * @offset: offset from the start of the file. 1126e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 1127a5f4374aSIngo Molnar * 112838e967aeSRavi Bangoria * Apart from the access refcount, __uprobe_register() takes a creation 1129a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 1130a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 1131a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 1132a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 1133e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 113438e967aeSRavi Bangoria * unregisters. Caller of __uprobe_register() is required to keep @inode 113561f94203SSong Liu * (and the containing mount) referenced. 1136a5f4374aSIngo Molnar * 1137a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 1138a5f4374aSIngo Molnar * else return 0 (success) 1139a5f4374aSIngo Molnar */ 114038e967aeSRavi Bangoria static int __uprobe_register(struct inode *inode, loff_t offset, 11411cc33161SRavi Bangoria loff_t ref_ctr_offset, struct uprobe_consumer *uc) 1142a5f4374aSIngo Molnar { 1143a5f4374aSIngo Molnar struct uprobe *uprobe; 1144a5f4374aSIngo Molnar int ret; 1145a5f4374aSIngo Molnar 1146ea024870SAnton Arapov /* Uprobe must have at least one set consumer */ 1147ea024870SAnton Arapov if (!uc->handler && !uc->ret_handler) 1148ea024870SAnton Arapov return -EINVAL; 1149ea024870SAnton Arapov 115040814f68SOleg Nesterov /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ 115140814f68SOleg Nesterov if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) 115241ccba02SOleg Nesterov return -EIO; 1153f0744af7SOleg Nesterov /* Racy, just to catch the obvious mistakes */ 1154a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 1155a5f4374aSIngo Molnar return -EINVAL; 1156a5f4374aSIngo Molnar 1157013b2debSOleg Nesterov /* 1158013b2debSOleg Nesterov * This ensures that copy_from_page(), copy_to_page() and 1159013b2debSOleg Nesterov * __update_ref_ctr() can't cross page boundary. 1160013b2debSOleg Nesterov */ 1161013b2debSOleg Nesterov if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE)) 1162013b2debSOleg Nesterov return -EINVAL; 1163013b2debSOleg Nesterov if (!IS_ALIGNED(ref_ctr_offset, sizeof(short))) 1164013b2debSOleg Nesterov return -EINVAL; 1165013b2debSOleg Nesterov 116666d06dffSOleg Nesterov retry: 11671cc33161SRavi Bangoria uprobe = alloc_uprobe(inode, offset, ref_ctr_offset); 116866d06dffSOleg Nesterov if (!uprobe) 116966d06dffSOleg Nesterov return -ENOMEM; 117022bad382SRavi Bangoria if (IS_ERR(uprobe)) 117122bad382SRavi Bangoria return PTR_ERR(uprobe); 117222bad382SRavi Bangoria 117366d06dffSOleg Nesterov /* 117466d06dffSOleg Nesterov * We can race with uprobe_unregister()->delete_uprobe(). 117566d06dffSOleg Nesterov * Check uprobe_is_active() and retry if it is false. 117666d06dffSOleg Nesterov */ 1177e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 117866d06dffSOleg Nesterov ret = -EAGAIN; 117966d06dffSOleg Nesterov if (likely(uprobe_is_active(uprobe))) { 118038e967aeSRavi Bangoria consumer_add(uprobe, uc); 118138e967aeSRavi Bangoria ret = register_for_each_vma(uprobe, uc); 11829a98e03cSOleg Nesterov if (ret) 118304aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 1184a5f4374aSIngo Molnar } 118566d06dffSOleg Nesterov up_write(&uprobe->register_rwsem); 1186a5f4374aSIngo Molnar put_uprobe(uprobe); 1187a5f4374aSIngo Molnar 118866d06dffSOleg Nesterov if (unlikely(ret == -EAGAIN)) 118966d06dffSOleg Nesterov goto retry; 1190a5f4374aSIngo Molnar return ret; 1191a5f4374aSIngo Molnar } 119238e967aeSRavi Bangoria 119338e967aeSRavi Bangoria int uprobe_register(struct inode *inode, loff_t offset, 119438e967aeSRavi Bangoria struct uprobe_consumer *uc) 119538e967aeSRavi Bangoria { 11961cc33161SRavi Bangoria return __uprobe_register(inode, offset, 0, uc); 119738e967aeSRavi Bangoria } 1198e8440c14SJosh Stone EXPORT_SYMBOL_GPL(uprobe_register); 1199a5f4374aSIngo Molnar 12001cc33161SRavi Bangoria int uprobe_register_refctr(struct inode *inode, loff_t offset, 12011cc33161SRavi Bangoria loff_t ref_ctr_offset, struct uprobe_consumer *uc) 12021cc33161SRavi Bangoria { 12031cc33161SRavi Bangoria return __uprobe_register(inode, offset, ref_ctr_offset, uc); 12041cc33161SRavi Bangoria } 12051cc33161SRavi Bangoria EXPORT_SYMBOL_GPL(uprobe_register_refctr); 12061cc33161SRavi Bangoria 1207a5f4374aSIngo Molnar /* 1208788faab7STobias Tefke * uprobe_apply - unregister an already registered probe. 1209bdf8647cSOleg Nesterov * @inode: the file in which the probe has to be removed. 1210bdf8647cSOleg Nesterov * @offset: offset from the start of the file. 1211bdf8647cSOleg Nesterov * @uc: consumer which wants to add more or remove some breakpoints 1212bdf8647cSOleg Nesterov * @add: add or remove the breakpoints 1213bdf8647cSOleg Nesterov */ 1214bdf8647cSOleg Nesterov int uprobe_apply(struct inode *inode, loff_t offset, 1215bdf8647cSOleg Nesterov struct uprobe_consumer *uc, bool add) 1216bdf8647cSOleg Nesterov { 1217bdf8647cSOleg Nesterov struct uprobe *uprobe; 1218bdf8647cSOleg Nesterov struct uprobe_consumer *con; 1219bdf8647cSOleg Nesterov int ret = -ENOENT; 1220bdf8647cSOleg Nesterov 1221bdf8647cSOleg Nesterov uprobe = find_uprobe(inode, offset); 122206d07139SOleg Nesterov if (WARN_ON(!uprobe)) 1223bdf8647cSOleg Nesterov return ret; 1224bdf8647cSOleg Nesterov 1225bdf8647cSOleg Nesterov down_write(&uprobe->register_rwsem); 1226bdf8647cSOleg Nesterov for (con = uprobe->consumers; con && con != uc ; con = con->next) 1227bdf8647cSOleg Nesterov ; 1228bdf8647cSOleg Nesterov if (con) 1229bdf8647cSOleg Nesterov ret = register_for_each_vma(uprobe, add ? uc : NULL); 1230bdf8647cSOleg Nesterov up_write(&uprobe->register_rwsem); 1231bdf8647cSOleg Nesterov put_uprobe(uprobe); 1232bdf8647cSOleg Nesterov 1233bdf8647cSOleg Nesterov return ret; 1234bdf8647cSOleg Nesterov } 1235bdf8647cSOleg Nesterov 1236da1816b1SOleg Nesterov static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) 1237da1816b1SOleg Nesterov { 1238da1816b1SOleg Nesterov struct vm_area_struct *vma; 1239da1816b1SOleg Nesterov int err = 0; 1240da1816b1SOleg Nesterov 1241d8ed45c5SMichel Lespinasse mmap_read_lock(mm); 1242da1816b1SOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 1243da1816b1SOleg Nesterov unsigned long vaddr; 1244da1816b1SOleg Nesterov loff_t offset; 1245da1816b1SOleg Nesterov 1246da1816b1SOleg Nesterov if (!valid_vma(vma, false) || 1247f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 1248da1816b1SOleg Nesterov continue; 1249da1816b1SOleg Nesterov 1250da1816b1SOleg Nesterov offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; 1251da1816b1SOleg Nesterov if (uprobe->offset < offset || 1252da1816b1SOleg Nesterov uprobe->offset >= offset + vma->vm_end - vma->vm_start) 1253da1816b1SOleg Nesterov continue; 1254da1816b1SOleg Nesterov 1255da1816b1SOleg Nesterov vaddr = offset_to_vaddr(vma, uprobe->offset); 1256da1816b1SOleg Nesterov err |= remove_breakpoint(uprobe, mm, vaddr); 1257da1816b1SOleg Nesterov } 1258d8ed45c5SMichel Lespinasse mmap_read_unlock(mm); 1259da1816b1SOleg Nesterov 1260da1816b1SOleg Nesterov return err; 1261da1816b1SOleg Nesterov } 1262da1816b1SOleg Nesterov 1263891c3970SOleg Nesterov static struct rb_node * 1264891c3970SOleg Nesterov find_node_in_range(struct inode *inode, loff_t min, loff_t max) 1265a5f4374aSIngo Molnar { 1266a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 1267a5f4374aSIngo Molnar 1268a5f4374aSIngo Molnar while (n) { 1269891c3970SOleg Nesterov struct uprobe *u = rb_entry(n, struct uprobe, rb_node); 1270a5f4374aSIngo Molnar 1271891c3970SOleg Nesterov if (inode < u->inode) { 1272a5f4374aSIngo Molnar n = n->rb_left; 1273891c3970SOleg Nesterov } else if (inode > u->inode) { 1274a5f4374aSIngo Molnar n = n->rb_right; 1275891c3970SOleg Nesterov } else { 1276891c3970SOleg Nesterov if (max < u->offset) 1277891c3970SOleg Nesterov n = n->rb_left; 1278891c3970SOleg Nesterov else if (min > u->offset) 1279891c3970SOleg Nesterov n = n->rb_right; 1280891c3970SOleg Nesterov else 1281891c3970SOleg Nesterov break; 1282891c3970SOleg Nesterov } 1283a5f4374aSIngo Molnar } 1284a5f4374aSIngo Molnar 1285891c3970SOleg Nesterov return n; 1286a5f4374aSIngo Molnar } 1287a5f4374aSIngo Molnar 1288a5f4374aSIngo Molnar /* 1289891c3970SOleg Nesterov * For a given range in vma, build a list of probes that need to be inserted. 1290a5f4374aSIngo Molnar */ 1291891c3970SOleg Nesterov static void build_probe_list(struct inode *inode, 1292891c3970SOleg Nesterov struct vm_area_struct *vma, 1293891c3970SOleg Nesterov unsigned long start, unsigned long end, 1294891c3970SOleg Nesterov struct list_head *head) 1295a5f4374aSIngo Molnar { 1296891c3970SOleg Nesterov loff_t min, max; 1297891c3970SOleg Nesterov struct rb_node *n, *t; 1298891c3970SOleg Nesterov struct uprobe *u; 1299891c3970SOleg Nesterov 1300891c3970SOleg Nesterov INIT_LIST_HEAD(head); 1301cb113b47SOleg Nesterov min = vaddr_to_offset(vma, start); 1302891c3970SOleg Nesterov max = min + (end - start) - 1; 1303a5f4374aSIngo Molnar 13046f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 1305891c3970SOleg Nesterov n = find_node_in_range(inode, min, max); 1306891c3970SOleg Nesterov if (n) { 1307891c3970SOleg Nesterov for (t = n; t; t = rb_prev(t)) { 1308891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1309891c3970SOleg Nesterov if (u->inode != inode || u->offset < min) 1310a5f4374aSIngo Molnar break; 1311891c3970SOleg Nesterov list_add(&u->pending_list, head); 1312f231722aSOleg Nesterov get_uprobe(u); 1313a5f4374aSIngo Molnar } 1314891c3970SOleg Nesterov for (t = n; (t = rb_next(t)); ) { 1315891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1316891c3970SOleg Nesterov if (u->inode != inode || u->offset > max) 1317891c3970SOleg Nesterov break; 1318891c3970SOleg Nesterov list_add(&u->pending_list, head); 1319f231722aSOleg Nesterov get_uprobe(u); 1320891c3970SOleg Nesterov } 1321891c3970SOleg Nesterov } 13226f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 1323a5f4374aSIngo Molnar } 1324a5f4374aSIngo Molnar 13251cc33161SRavi Bangoria /* @vma contains reference counter, not the probed instruction. */ 13261cc33161SRavi Bangoria static int delayed_ref_ctr_inc(struct vm_area_struct *vma) 13271cc33161SRavi Bangoria { 13281cc33161SRavi Bangoria struct list_head *pos, *q; 13291cc33161SRavi Bangoria struct delayed_uprobe *du; 13301cc33161SRavi Bangoria unsigned long vaddr; 13311cc33161SRavi Bangoria int ret = 0, err = 0; 13321cc33161SRavi Bangoria 13331cc33161SRavi Bangoria mutex_lock(&delayed_uprobe_lock); 13341cc33161SRavi Bangoria list_for_each_safe(pos, q, &delayed_uprobe_list) { 13351cc33161SRavi Bangoria du = list_entry(pos, struct delayed_uprobe, list); 13361cc33161SRavi Bangoria 13371cc33161SRavi Bangoria if (du->mm != vma->vm_mm || 13381cc33161SRavi Bangoria !valid_ref_ctr_vma(du->uprobe, vma)) 13391cc33161SRavi Bangoria continue; 13401cc33161SRavi Bangoria 13411cc33161SRavi Bangoria vaddr = offset_to_vaddr(vma, du->uprobe->ref_ctr_offset); 13421cc33161SRavi Bangoria ret = __update_ref_ctr(vma->vm_mm, vaddr, 1); 13431cc33161SRavi Bangoria if (ret) { 13441cc33161SRavi Bangoria update_ref_ctr_warn(du->uprobe, vma->vm_mm, 1); 13451cc33161SRavi Bangoria if (!err) 13461cc33161SRavi Bangoria err = ret; 13471cc33161SRavi Bangoria } 13481cc33161SRavi Bangoria delayed_uprobe_delete(du); 13491cc33161SRavi Bangoria } 13501cc33161SRavi Bangoria mutex_unlock(&delayed_uprobe_lock); 13511cc33161SRavi Bangoria return err; 13521cc33161SRavi Bangoria } 13531cc33161SRavi Bangoria 1354a5f4374aSIngo Molnar /* 1355c1e8d7c6SMichel Lespinasse * Called from mmap_region/vma_adjust with mm->mmap_lock acquired. 1356a5f4374aSIngo Molnar * 13575e5be71aSOleg Nesterov * Currently we ignore all errors and always return 0, the callers 13585e5be71aSOleg Nesterov * can't handle the failure anyway. 1359a5f4374aSIngo Molnar */ 1360a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1361a5f4374aSIngo Molnar { 1362a5f4374aSIngo Molnar struct list_head tmp_list; 1363665605a2SOleg Nesterov struct uprobe *uprobe, *u; 1364a5f4374aSIngo Molnar struct inode *inode; 1365a5f4374aSIngo Molnar 13661cc33161SRavi Bangoria if (no_uprobe_events()) 13671cc33161SRavi Bangoria return 0; 13681cc33161SRavi Bangoria 13691cc33161SRavi Bangoria if (vma->vm_file && 13701cc33161SRavi Bangoria (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && 13711cc33161SRavi Bangoria test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) 13721cc33161SRavi Bangoria delayed_ref_ctr_inc(vma); 13731cc33161SRavi Bangoria 13741cc33161SRavi Bangoria if (!valid_vma(vma, true)) 1375a5f4374aSIngo Molnar return 0; 1376a5f4374aSIngo Molnar 1377f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 1378a5f4374aSIngo Molnar if (!inode) 1379a5f4374aSIngo Molnar return 0; 1380a5f4374aSIngo Molnar 1381a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1382891c3970SOleg Nesterov build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); 1383806a98bdSOleg Nesterov /* 1384806a98bdSOleg Nesterov * We can race with uprobe_unregister(), this uprobe can be already 1385806a98bdSOleg Nesterov * removed. But in this case filter_chain() must return false, all 1386806a98bdSOleg Nesterov * consumers have gone away. 1387806a98bdSOleg Nesterov */ 1388665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 1389806a98bdSOleg Nesterov if (!fatal_signal_pending(current) && 13908a7f2fa0SOleg Nesterov filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { 139157683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 13925e5be71aSOleg Nesterov install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1393a5f4374aSIngo Molnar } 1394a5f4374aSIngo Molnar put_uprobe(uprobe); 1395a5f4374aSIngo Molnar } 1396a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1397a5f4374aSIngo Molnar 13985e5be71aSOleg Nesterov return 0; 1399a5f4374aSIngo Molnar } 1400a5f4374aSIngo Molnar 14019f68f672SOleg Nesterov static bool 14029f68f672SOleg Nesterov vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) 14039f68f672SOleg Nesterov { 14049f68f672SOleg Nesterov loff_t min, max; 14059f68f672SOleg Nesterov struct inode *inode; 14069f68f672SOleg Nesterov struct rb_node *n; 14079f68f672SOleg Nesterov 1408f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 14099f68f672SOleg Nesterov 14109f68f672SOleg Nesterov min = vaddr_to_offset(vma, start); 14119f68f672SOleg Nesterov max = min + (end - start) - 1; 14129f68f672SOleg Nesterov 14139f68f672SOleg Nesterov spin_lock(&uprobes_treelock); 14149f68f672SOleg Nesterov n = find_node_in_range(inode, min, max); 14159f68f672SOleg Nesterov spin_unlock(&uprobes_treelock); 14169f68f672SOleg Nesterov 14179f68f672SOleg Nesterov return !!n; 14189f68f672SOleg Nesterov } 14199f68f672SOleg Nesterov 1420682968e0SSrikar Dronamraju /* 1421682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1422682968e0SSrikar Dronamraju */ 1423cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1424682968e0SSrikar Dronamraju { 1425441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, false)) 1426682968e0SSrikar Dronamraju return; 1427682968e0SSrikar Dronamraju 14282fd611a9SOleg Nesterov if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ 14292fd611a9SOleg Nesterov return; 14302fd611a9SOleg Nesterov 14319f68f672SOleg Nesterov if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || 14329f68f672SOleg Nesterov test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) 1433f8ac4ec9SOleg Nesterov return; 1434f8ac4ec9SOleg Nesterov 14359f68f672SOleg Nesterov if (vma_has_uprobes(vma, start, end)) 14369f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); 1437682968e0SSrikar Dronamraju } 1438682968e0SSrikar Dronamraju 1439d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 14406441ec8bSOleg Nesterov static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) 1441d4b3b638SSrikar Dronamraju { 1442704bde3cSOleg Nesterov struct vm_area_struct *vma; 1443704bde3cSOleg Nesterov int ret; 1444d4b3b638SSrikar Dronamraju 1445d8ed45c5SMichel Lespinasse if (mmap_write_lock_killable(mm)) 1446598fdc1dSMichal Hocko return -EINTR; 1447598fdc1dSMichal Hocko 1448704bde3cSOleg Nesterov if (mm->uprobes_state.xol_area) { 1449704bde3cSOleg Nesterov ret = -EALREADY; 1450d4b3b638SSrikar Dronamraju goto fail; 1451704bde3cSOleg Nesterov } 1452d4b3b638SSrikar Dronamraju 1453af0d95afSOleg Nesterov if (!area->vaddr) { 1454d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1455af0d95afSOleg Nesterov area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, 1456af0d95afSOleg Nesterov PAGE_SIZE, 0, 0); 1457ff68dac6SGaowei Pu if (IS_ERR_VALUE(area->vaddr)) { 1458d4b3b638SSrikar Dronamraju ret = area->vaddr; 1459d4b3b638SSrikar Dronamraju goto fail; 1460d4b3b638SSrikar Dronamraju } 1461af0d95afSOleg Nesterov } 1462d4b3b638SSrikar Dronamraju 1463704bde3cSOleg Nesterov vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1464704bde3cSOleg Nesterov VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, 1465704bde3cSOleg Nesterov &area->xol_mapping); 1466704bde3cSOleg Nesterov if (IS_ERR(vma)) { 1467704bde3cSOleg Nesterov ret = PTR_ERR(vma); 1468d4b3b638SSrikar Dronamraju goto fail; 1469704bde3cSOleg Nesterov } 1470d4b3b638SSrikar Dronamraju 1471704bde3cSOleg Nesterov ret = 0; 14725c6338b4SPaul E. McKenney /* pairs with get_xol_area() */ 14735c6338b4SPaul E. McKenney smp_store_release(&mm->uprobes_state.xol_area, area); /* ^^^ */ 1474d4b3b638SSrikar Dronamraju fail: 1475d8ed45c5SMichel Lespinasse mmap_write_unlock(mm); 1476d4b3b638SSrikar Dronamraju 1477d4b3b638SSrikar Dronamraju return ret; 1478d4b3b638SSrikar Dronamraju } 1479d4b3b638SSrikar Dronamraju 1480af0d95afSOleg Nesterov static struct xol_area *__create_xol_area(unsigned long vaddr) 1481d4b3b638SSrikar Dronamraju { 14829b545df8SOleg Nesterov struct mm_struct *mm = current->mm; 1483e78aebfdSAnton Arapov uprobe_opcode_t insn = UPROBE_SWBP_INSN; 14846441ec8bSOleg Nesterov struct xol_area *area; 14859b545df8SOleg Nesterov 1486af0d95afSOleg Nesterov area = kmalloc(sizeof(*area), GFP_KERNEL); 1487d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1488c8a82538SOleg Nesterov goto out; 1489d4b3b638SSrikar Dronamraju 14906396bb22SKees Cook area->bitmap = kcalloc(BITS_TO_LONGS(UINSNS_PER_PAGE), sizeof(long), 14916396bb22SKees Cook GFP_KERNEL); 1492d4b3b638SSrikar Dronamraju if (!area->bitmap) 1493c8a82538SOleg Nesterov goto free_area; 1494c8a82538SOleg Nesterov 1495704bde3cSOleg Nesterov area->xol_mapping.name = "[uprobes]"; 1496869ae761SOleg Nesterov area->xol_mapping.fault = NULL; 1497704bde3cSOleg Nesterov area->xol_mapping.pages = area->pages; 1498f58bea2fSOleg Nesterov area->pages[0] = alloc_page(GFP_HIGHUSER); 1499f58bea2fSOleg Nesterov if (!area->pages[0]) 1500c8a82538SOleg Nesterov goto free_bitmap; 1501f58bea2fSOleg Nesterov area->pages[1] = NULL; 1502d4b3b638SSrikar Dronamraju 1503af0d95afSOleg Nesterov area->vaddr = vaddr; 1504d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 15056441ec8bSOleg Nesterov /* Reserve the 1st slot for get_trampoline_vaddr() */ 15066441ec8bSOleg Nesterov set_bit(0, area->bitmap); 15076441ec8bSOleg Nesterov atomic_set(&area->slot_count, 1); 1508297e765eSMarcin Nowakowski arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); 1509e78aebfdSAnton Arapov 15106441ec8bSOleg Nesterov if (!xol_add_vma(mm, area)) 1511d4b3b638SSrikar Dronamraju return area; 1512d4b3b638SSrikar Dronamraju 1513f58bea2fSOleg Nesterov __free_page(area->pages[0]); 1514c8a82538SOleg Nesterov free_bitmap: 1515d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1516c8a82538SOleg Nesterov free_area: 1517d4b3b638SSrikar Dronamraju kfree(area); 1518c8a82538SOleg Nesterov out: 15196441ec8bSOleg Nesterov return NULL; 15206441ec8bSOleg Nesterov } 15216441ec8bSOleg Nesterov 15226441ec8bSOleg Nesterov /* 15236441ec8bSOleg Nesterov * get_xol_area - Allocate process's xol_area if necessary. 15246441ec8bSOleg Nesterov * This area will be used for storing instructions for execution out of line. 15256441ec8bSOleg Nesterov * 15266441ec8bSOleg Nesterov * Returns the allocated area or NULL. 15276441ec8bSOleg Nesterov */ 15286441ec8bSOleg Nesterov static struct xol_area *get_xol_area(void) 15296441ec8bSOleg Nesterov { 15306441ec8bSOleg Nesterov struct mm_struct *mm = current->mm; 15316441ec8bSOleg Nesterov struct xol_area *area; 15326441ec8bSOleg Nesterov 15336441ec8bSOleg Nesterov if (!mm->uprobes_state.xol_area) 1534af0d95afSOleg Nesterov __create_xol_area(0); 15356441ec8bSOleg Nesterov 15365c6338b4SPaul E. McKenney /* Pairs with xol_add_vma() smp_store_release() */ 15375c6338b4SPaul E. McKenney area = READ_ONCE(mm->uprobes_state.xol_area); /* ^^^ */ 15389b545df8SOleg Nesterov return area; 1539d4b3b638SSrikar Dronamraju } 1540d4b3b638SSrikar Dronamraju 1541d4b3b638SSrikar Dronamraju /* 1542d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1543d4b3b638SSrikar Dronamraju */ 1544d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1545d4b3b638SSrikar Dronamraju { 1546d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1547d4b3b638SSrikar Dronamraju 15481cc33161SRavi Bangoria mutex_lock(&delayed_uprobe_lock); 15491cc33161SRavi Bangoria delayed_uprobe_remove(NULL, mm); 15501cc33161SRavi Bangoria mutex_unlock(&delayed_uprobe_lock); 15511cc33161SRavi Bangoria 1552d4b3b638SSrikar Dronamraju if (!area) 1553d4b3b638SSrikar Dronamraju return; 1554d4b3b638SSrikar Dronamraju 1555f58bea2fSOleg Nesterov put_page(area->pages[0]); 1556d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1557d4b3b638SSrikar Dronamraju kfree(area); 1558d4b3b638SSrikar Dronamraju } 1559d4b3b638SSrikar Dronamraju 156032cdba1eSOleg Nesterov void uprobe_start_dup_mmap(void) 156132cdba1eSOleg Nesterov { 156232cdba1eSOleg Nesterov percpu_down_read(&dup_mmap_sem); 156332cdba1eSOleg Nesterov } 156432cdba1eSOleg Nesterov 156532cdba1eSOleg Nesterov void uprobe_end_dup_mmap(void) 156632cdba1eSOleg Nesterov { 156732cdba1eSOleg Nesterov percpu_up_read(&dup_mmap_sem); 156832cdba1eSOleg Nesterov } 156932cdba1eSOleg Nesterov 1570f8ac4ec9SOleg Nesterov void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) 1571f8ac4ec9SOleg Nesterov { 15729f68f672SOleg Nesterov if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { 1573f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &newmm->flags); 15749f68f672SOleg Nesterov /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ 15759f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &newmm->flags); 15769f68f672SOleg Nesterov } 1577f8ac4ec9SOleg Nesterov } 1578f8ac4ec9SOleg Nesterov 1579d4b3b638SSrikar Dronamraju /* 1580d4b3b638SSrikar Dronamraju * - search for a free slot. 1581d4b3b638SSrikar Dronamraju */ 1582d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1583d4b3b638SSrikar Dronamraju { 1584d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1585d4b3b638SSrikar Dronamraju int slot_nr; 1586d4b3b638SSrikar Dronamraju 1587d4b3b638SSrikar Dronamraju do { 1588d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1589d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1590d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1591d4b3b638SSrikar Dronamraju break; 1592d4b3b638SSrikar Dronamraju 1593d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1594d4b3b638SSrikar Dronamraju continue; 1595d4b3b638SSrikar Dronamraju } 1596d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1597d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1598d4b3b638SSrikar Dronamraju 1599d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1600d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1601d4b3b638SSrikar Dronamraju 1602d4b3b638SSrikar Dronamraju return slot_addr; 1603d4b3b638SSrikar Dronamraju } 1604d4b3b638SSrikar Dronamraju 1605d4b3b638SSrikar Dronamraju /* 1606a6cb3f6dSOleg Nesterov * xol_get_insn_slot - allocate a slot for xol. 1607d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1608d4b3b638SSrikar Dronamraju */ 1609a6cb3f6dSOleg Nesterov static unsigned long xol_get_insn_slot(struct uprobe *uprobe) 1610d4b3b638SSrikar Dronamraju { 1611d4b3b638SSrikar Dronamraju struct xol_area *area; 1612a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1613d4b3b638SSrikar Dronamraju 16149b545df8SOleg Nesterov area = get_xol_area(); 1615d4b3b638SSrikar Dronamraju if (!area) 1616d4b3b638SSrikar Dronamraju return 0; 1617d4b3b638SSrikar Dronamraju 1618a6cb3f6dSOleg Nesterov xol_vaddr = xol_take_insn_slot(area); 1619a6cb3f6dSOleg Nesterov if (unlikely(!xol_vaddr)) 1620d4b3b638SSrikar Dronamraju return 0; 1621d4b3b638SSrikar Dronamraju 1622f58bea2fSOleg Nesterov arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, 1623803200e2SOleg Nesterov &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); 1624d4b3b638SSrikar Dronamraju 1625a6cb3f6dSOleg Nesterov return xol_vaddr; 1626d4b3b638SSrikar Dronamraju } 1627d4b3b638SSrikar Dronamraju 1628d4b3b638SSrikar Dronamraju /* 1629d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1630d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1631d4b3b638SSrikar Dronamraju * subsequent requests. 1632d4b3b638SSrikar Dronamraju */ 1633d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1634d4b3b638SSrikar Dronamraju { 1635d4b3b638SSrikar Dronamraju struct xol_area *area; 1636d4b3b638SSrikar Dronamraju unsigned long vma_end; 1637d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1638d4b3b638SSrikar Dronamraju 1639d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1640d4b3b638SSrikar Dronamraju return; 1641d4b3b638SSrikar Dronamraju 1642d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1643af4355e9SOleg Nesterov if (unlikely(!slot_addr)) 1644d4b3b638SSrikar Dronamraju return; 1645d4b3b638SSrikar Dronamraju 1646d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1647d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1648d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1649d4b3b638SSrikar Dronamraju unsigned long offset; 1650d4b3b638SSrikar Dronamraju int slot_nr; 1651d4b3b638SSrikar Dronamraju 1652d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1653d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1654d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1655d4b3b638SSrikar Dronamraju return; 1656d4b3b638SSrikar Dronamraju 1657d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1658d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 16592a742cedSOleg Nesterov smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ 1660d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1661d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1662d4b3b638SSrikar Dronamraju 1663d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1664d4b3b638SSrikar Dronamraju } 1665d4b3b638SSrikar Dronamraju } 1666d4b3b638SSrikar Dronamraju 166772e6ae28SVictor Kamensky void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, 166872e6ae28SVictor Kamensky void *src, unsigned long len) 166972e6ae28SVictor Kamensky { 167072e6ae28SVictor Kamensky /* Initialize the slot */ 167172e6ae28SVictor Kamensky copy_to_page(page, vaddr, src, len); 167272e6ae28SVictor Kamensky 167372e6ae28SVictor Kamensky /* 1674885f7f8eSChristoph Hellwig * We probably need flush_icache_user_page() but it needs vma. 167572e6ae28SVictor Kamensky * This should work on most of architectures by default. If 167672e6ae28SVictor Kamensky * architecture needs to do something different it can define 167772e6ae28SVictor Kamensky * its own version of the function. 167872e6ae28SVictor Kamensky */ 167972e6ae28SVictor Kamensky flush_dcache_page(page); 168072e6ae28SVictor Kamensky } 168172e6ae28SVictor Kamensky 16820326f5a9SSrikar Dronamraju /** 16830326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 16840326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 16850326f5a9SSrikar Dronamraju * instruction. 16860326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 16870326f5a9SSrikar Dronamraju */ 16880326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 16890326f5a9SSrikar Dronamraju { 16900326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 16910326f5a9SSrikar Dronamraju } 16920326f5a9SSrikar Dronamraju 1693b02ef20aSOleg Nesterov unsigned long uprobe_get_trap_addr(struct pt_regs *regs) 1694b02ef20aSOleg Nesterov { 1695b02ef20aSOleg Nesterov struct uprobe_task *utask = current->utask; 1696b02ef20aSOleg Nesterov 1697b02ef20aSOleg Nesterov if (unlikely(utask && utask->active_uprobe)) 1698b02ef20aSOleg Nesterov return utask->vaddr; 1699b02ef20aSOleg Nesterov 1700b02ef20aSOleg Nesterov return instruction_pointer(regs); 1701b02ef20aSOleg Nesterov } 1702b02ef20aSOleg Nesterov 17032bb5e840SOleg Nesterov static struct return_instance *free_ret_instance(struct return_instance *ri) 17042bb5e840SOleg Nesterov { 17052bb5e840SOleg Nesterov struct return_instance *next = ri->next; 17062bb5e840SOleg Nesterov put_uprobe(ri->uprobe); 17072bb5e840SOleg Nesterov kfree(ri); 17082bb5e840SOleg Nesterov return next; 17092bb5e840SOleg Nesterov } 17102bb5e840SOleg Nesterov 17110326f5a9SSrikar Dronamraju /* 17120326f5a9SSrikar Dronamraju * Called with no locks held. 1713788faab7STobias Tefke * Called in context of an exiting or an exec-ing thread. 17140326f5a9SSrikar Dronamraju */ 17150326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 17160326f5a9SSrikar Dronamraju { 17170326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 17182bb5e840SOleg Nesterov struct return_instance *ri; 17190326f5a9SSrikar Dronamraju 17200326f5a9SSrikar Dronamraju if (!utask) 17210326f5a9SSrikar Dronamraju return; 17220326f5a9SSrikar Dronamraju 17230326f5a9SSrikar Dronamraju if (utask->active_uprobe) 17240326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 17250326f5a9SSrikar Dronamraju 17260dfd0eb8SAnton Arapov ri = utask->return_instances; 17272bb5e840SOleg Nesterov while (ri) 17282bb5e840SOleg Nesterov ri = free_ret_instance(ri); 17290dfd0eb8SAnton Arapov 1730d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 17310326f5a9SSrikar Dronamraju kfree(utask); 17320326f5a9SSrikar Dronamraju t->utask = NULL; 17330326f5a9SSrikar Dronamraju } 17340326f5a9SSrikar Dronamraju 17350326f5a9SSrikar Dronamraju /* 17365a2df662SOleg Nesterov * Allocate a uprobe_task object for the task if if necessary. 17375a2df662SOleg Nesterov * Called when the thread hits a breakpoint. 17380326f5a9SSrikar Dronamraju * 17390326f5a9SSrikar Dronamraju * Returns: 17400326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 17410326f5a9SSrikar Dronamraju * - NULL otherwise 17420326f5a9SSrikar Dronamraju */ 17435a2df662SOleg Nesterov static struct uprobe_task *get_utask(void) 17440326f5a9SSrikar Dronamraju { 17455a2df662SOleg Nesterov if (!current->utask) 17465a2df662SOleg Nesterov current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 17475a2df662SOleg Nesterov return current->utask; 17480326f5a9SSrikar Dronamraju } 17490326f5a9SSrikar Dronamraju 1750248d3a7bSOleg Nesterov static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) 1751248d3a7bSOleg Nesterov { 1752248d3a7bSOleg Nesterov struct uprobe_task *n_utask; 1753248d3a7bSOleg Nesterov struct return_instance **p, *o, *n; 1754248d3a7bSOleg Nesterov 1755248d3a7bSOleg Nesterov n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 1756248d3a7bSOleg Nesterov if (!n_utask) 1757248d3a7bSOleg Nesterov return -ENOMEM; 1758248d3a7bSOleg Nesterov t->utask = n_utask; 1759248d3a7bSOleg Nesterov 1760248d3a7bSOleg Nesterov p = &n_utask->return_instances; 1761248d3a7bSOleg Nesterov for (o = o_utask->return_instances; o; o = o->next) { 1762248d3a7bSOleg Nesterov n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); 1763248d3a7bSOleg Nesterov if (!n) 1764248d3a7bSOleg Nesterov return -ENOMEM; 1765248d3a7bSOleg Nesterov 1766248d3a7bSOleg Nesterov *n = *o; 1767f231722aSOleg Nesterov get_uprobe(n->uprobe); 1768248d3a7bSOleg Nesterov n->next = NULL; 1769248d3a7bSOleg Nesterov 1770248d3a7bSOleg Nesterov *p = n; 1771248d3a7bSOleg Nesterov p = &n->next; 1772248d3a7bSOleg Nesterov n_utask->depth++; 1773248d3a7bSOleg Nesterov } 1774248d3a7bSOleg Nesterov 1775248d3a7bSOleg Nesterov return 0; 1776248d3a7bSOleg Nesterov } 1777248d3a7bSOleg Nesterov 1778248d3a7bSOleg Nesterov static void uprobe_warn(struct task_struct *t, const char *msg) 1779248d3a7bSOleg Nesterov { 1780248d3a7bSOleg Nesterov pr_warn("uprobe: %s:%d failed to %s\n", 1781248d3a7bSOleg Nesterov current->comm, current->pid, msg); 1782248d3a7bSOleg Nesterov } 1783248d3a7bSOleg Nesterov 1784aa59c53fSOleg Nesterov static void dup_xol_work(struct callback_head *work) 1785aa59c53fSOleg Nesterov { 1786aa59c53fSOleg Nesterov if (current->flags & PF_EXITING) 1787aa59c53fSOleg Nesterov return; 1788aa59c53fSOleg Nesterov 1789598fdc1dSMichal Hocko if (!__create_xol_area(current->utask->dup_xol_addr) && 1790598fdc1dSMichal Hocko !fatal_signal_pending(current)) 1791aa59c53fSOleg Nesterov uprobe_warn(current, "dup xol area"); 1792aa59c53fSOleg Nesterov } 1793aa59c53fSOleg Nesterov 1794e78aebfdSAnton Arapov /* 1795b68e0749SOleg Nesterov * Called in context of a new clone/fork from copy_process. 1796b68e0749SOleg Nesterov */ 17973ab67966SOleg Nesterov void uprobe_copy_process(struct task_struct *t, unsigned long flags) 1798b68e0749SOleg Nesterov { 1799248d3a7bSOleg Nesterov struct uprobe_task *utask = current->utask; 1800248d3a7bSOleg Nesterov struct mm_struct *mm = current->mm; 1801aa59c53fSOleg Nesterov struct xol_area *area; 1802248d3a7bSOleg Nesterov 1803b68e0749SOleg Nesterov t->utask = NULL; 1804248d3a7bSOleg Nesterov 18053ab67966SOleg Nesterov if (!utask || !utask->return_instances) 18063ab67966SOleg Nesterov return; 18073ab67966SOleg Nesterov 18083ab67966SOleg Nesterov if (mm == t->mm && !(flags & CLONE_VFORK)) 1809248d3a7bSOleg Nesterov return; 1810248d3a7bSOleg Nesterov 1811248d3a7bSOleg Nesterov if (dup_utask(t, utask)) 1812248d3a7bSOleg Nesterov return uprobe_warn(t, "dup ret instances"); 1813aa59c53fSOleg Nesterov 1814aa59c53fSOleg Nesterov /* The task can fork() after dup_xol_work() fails */ 1815aa59c53fSOleg Nesterov area = mm->uprobes_state.xol_area; 1816aa59c53fSOleg Nesterov if (!area) 1817aa59c53fSOleg Nesterov return uprobe_warn(t, "dup xol area"); 1818aa59c53fSOleg Nesterov 18193ab67966SOleg Nesterov if (mm == t->mm) 18203ab67966SOleg Nesterov return; 18213ab67966SOleg Nesterov 182232473431SOleg Nesterov t->utask->dup_xol_addr = area->vaddr; 182332473431SOleg Nesterov init_task_work(&t->utask->dup_xol_work, dup_xol_work); 182491989c70SJens Axboe task_work_add(t, &t->utask->dup_xol_work, TWA_RESUME); 1825b68e0749SOleg Nesterov } 1826b68e0749SOleg Nesterov 1827b68e0749SOleg Nesterov /* 1828e78aebfdSAnton Arapov * Current area->vaddr notion assume the trampoline address is always 1829e78aebfdSAnton Arapov * equal area->vaddr. 1830e78aebfdSAnton Arapov * 1831e78aebfdSAnton Arapov * Returns -1 in case the xol_area is not allocated. 1832e78aebfdSAnton Arapov */ 1833e78aebfdSAnton Arapov static unsigned long get_trampoline_vaddr(void) 1834e78aebfdSAnton Arapov { 1835e78aebfdSAnton Arapov struct xol_area *area; 1836e78aebfdSAnton Arapov unsigned long trampoline_vaddr = -1; 1837e78aebfdSAnton Arapov 18385c6338b4SPaul E. McKenney /* Pairs with xol_add_vma() smp_store_release() */ 18395c6338b4SPaul E. McKenney area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */ 1840e78aebfdSAnton Arapov if (area) 1841e78aebfdSAnton Arapov trampoline_vaddr = area->vaddr; 1842e78aebfdSAnton Arapov 1843e78aebfdSAnton Arapov return trampoline_vaddr; 1844e78aebfdSAnton Arapov } 1845e78aebfdSAnton Arapov 1846db087ef6SOleg Nesterov static void cleanup_return_instances(struct uprobe_task *utask, bool chained, 1847db087ef6SOleg Nesterov struct pt_regs *regs) 1848a5b7e1a8SOleg Nesterov { 1849a5b7e1a8SOleg Nesterov struct return_instance *ri = utask->return_instances; 1850db087ef6SOleg Nesterov enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL; 185186dcb702SOleg Nesterov 185286dcb702SOleg Nesterov while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) { 1853a5b7e1a8SOleg Nesterov ri = free_ret_instance(ri); 1854a5b7e1a8SOleg Nesterov utask->depth--; 1855a5b7e1a8SOleg Nesterov } 1856a5b7e1a8SOleg Nesterov utask->return_instances = ri; 1857a5b7e1a8SOleg Nesterov } 1858a5b7e1a8SOleg Nesterov 18590dfd0eb8SAnton Arapov static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) 18600dfd0eb8SAnton Arapov { 18610dfd0eb8SAnton Arapov struct return_instance *ri; 18620dfd0eb8SAnton Arapov struct uprobe_task *utask; 18630dfd0eb8SAnton Arapov unsigned long orig_ret_vaddr, trampoline_vaddr; 1864db087ef6SOleg Nesterov bool chained; 18650dfd0eb8SAnton Arapov 18660dfd0eb8SAnton Arapov if (!get_xol_area()) 18670dfd0eb8SAnton Arapov return; 18680dfd0eb8SAnton Arapov 18690dfd0eb8SAnton Arapov utask = get_utask(); 18700dfd0eb8SAnton Arapov if (!utask) 18710dfd0eb8SAnton Arapov return; 18720dfd0eb8SAnton Arapov 1873ded49c55SAnton Arapov if (utask->depth >= MAX_URETPROBE_DEPTH) { 1874ded49c55SAnton Arapov printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" 1875ded49c55SAnton Arapov " nestedness limit pid/tgid=%d/%d\n", 1876ded49c55SAnton Arapov current->pid, current->tgid); 1877ded49c55SAnton Arapov return; 1878ded49c55SAnton Arapov } 1879ded49c55SAnton Arapov 18806c58d0e4SOleg Nesterov ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); 18810dfd0eb8SAnton Arapov if (!ri) 18826c58d0e4SOleg Nesterov return; 18830dfd0eb8SAnton Arapov 18840dfd0eb8SAnton Arapov trampoline_vaddr = get_trampoline_vaddr(); 18850dfd0eb8SAnton Arapov orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); 18860dfd0eb8SAnton Arapov if (orig_ret_vaddr == -1) 18870dfd0eb8SAnton Arapov goto fail; 18880dfd0eb8SAnton Arapov 1889a5b7e1a8SOleg Nesterov /* drop the entries invalidated by longjmp() */ 1890db087ef6SOleg Nesterov chained = (orig_ret_vaddr == trampoline_vaddr); 1891db087ef6SOleg Nesterov cleanup_return_instances(utask, chained, regs); 1892a5b7e1a8SOleg Nesterov 18930dfd0eb8SAnton Arapov /* 18940dfd0eb8SAnton Arapov * We don't want to keep trampoline address in stack, rather keep the 18950dfd0eb8SAnton Arapov * original return address of first caller thru all the consequent 18960dfd0eb8SAnton Arapov * instances. This also makes breakpoint unwrapping easier. 18970dfd0eb8SAnton Arapov */ 1898db087ef6SOleg Nesterov if (chained) { 18990dfd0eb8SAnton Arapov if (!utask->return_instances) { 19000dfd0eb8SAnton Arapov /* 19010dfd0eb8SAnton Arapov * This situation is not possible. Likely we have an 19020dfd0eb8SAnton Arapov * attack from user-space. 19030dfd0eb8SAnton Arapov */ 19046c58d0e4SOleg Nesterov uprobe_warn(current, "handle tail call"); 19050dfd0eb8SAnton Arapov goto fail; 19060dfd0eb8SAnton Arapov } 19070dfd0eb8SAnton Arapov orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; 19080dfd0eb8SAnton Arapov } 19090dfd0eb8SAnton Arapov 1910f231722aSOleg Nesterov ri->uprobe = get_uprobe(uprobe); 19110dfd0eb8SAnton Arapov ri->func = instruction_pointer(regs); 19127b868e48SOleg Nesterov ri->stack = user_stack_pointer(regs); 19130dfd0eb8SAnton Arapov ri->orig_ret_vaddr = orig_ret_vaddr; 19140dfd0eb8SAnton Arapov ri->chained = chained; 19150dfd0eb8SAnton Arapov 1916ded49c55SAnton Arapov utask->depth++; 19170dfd0eb8SAnton Arapov ri->next = utask->return_instances; 19180dfd0eb8SAnton Arapov utask->return_instances = ri; 19190dfd0eb8SAnton Arapov 19200dfd0eb8SAnton Arapov return; 19210dfd0eb8SAnton Arapov fail: 19220dfd0eb8SAnton Arapov kfree(ri); 19230dfd0eb8SAnton Arapov } 19240dfd0eb8SAnton Arapov 19250326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 19260326f5a9SSrikar Dronamraju static int 1927a6cb3f6dSOleg Nesterov pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) 19280326f5a9SSrikar Dronamraju { 1929a6cb3f6dSOleg Nesterov struct uprobe_task *utask; 1930a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1931aba51024SOleg Nesterov int err; 1932d4b3b638SSrikar Dronamraju 1933608e7427SOleg Nesterov utask = get_utask(); 1934608e7427SOleg Nesterov if (!utask) 1935608e7427SOleg Nesterov return -ENOMEM; 1936a6cb3f6dSOleg Nesterov 1937a6cb3f6dSOleg Nesterov xol_vaddr = xol_get_insn_slot(uprobe); 1938a6cb3f6dSOleg Nesterov if (!xol_vaddr) 1939a6cb3f6dSOleg Nesterov return -ENOMEM; 1940a6cb3f6dSOleg Nesterov 1941a6cb3f6dSOleg Nesterov utask->xol_vaddr = xol_vaddr; 1942a6cb3f6dSOleg Nesterov utask->vaddr = bp_vaddr; 1943a6cb3f6dSOleg Nesterov 1944aba51024SOleg Nesterov err = arch_uprobe_pre_xol(&uprobe->arch, regs); 1945aba51024SOleg Nesterov if (unlikely(err)) { 1946aba51024SOleg Nesterov xol_free_insn_slot(current); 1947aba51024SOleg Nesterov return err; 1948aba51024SOleg Nesterov } 1949aba51024SOleg Nesterov 1950608e7427SOleg Nesterov utask->active_uprobe = uprobe; 1951608e7427SOleg Nesterov utask->state = UTASK_SSTEP; 1952aba51024SOleg Nesterov return 0; 19530326f5a9SSrikar Dronamraju } 19540326f5a9SSrikar Dronamraju 19550326f5a9SSrikar Dronamraju /* 19560326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 19570326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 19580326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 19590326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 19600326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 19610326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 19620326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 19630326f5a9SSrikar Dronamraju */ 19640326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 19650326f5a9SSrikar Dronamraju { 19660326f5a9SSrikar Dronamraju struct task_struct *t = current; 19670326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 19680326f5a9SSrikar Dronamraju 19690326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 19700326f5a9SSrikar Dronamraju return false; 19710326f5a9SSrikar Dronamraju 19720326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 19730326f5a9SSrikar Dronamraju 19745c251e9dSJens Axboe if (task_sigpending(t)) { 19750326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 19760326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 19770326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 19780326f5a9SSrikar Dronamraju 19790326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 19800326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 19810326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 19820326f5a9SSrikar Dronamraju } 19830326f5a9SSrikar Dronamraju } 19840326f5a9SSrikar Dronamraju 19850326f5a9SSrikar Dronamraju return true; 19860326f5a9SSrikar Dronamraju } 19870326f5a9SSrikar Dronamraju 1988499a4f3eSOleg Nesterov static void mmf_recalc_uprobes(struct mm_struct *mm) 1989499a4f3eSOleg Nesterov { 1990499a4f3eSOleg Nesterov struct vm_area_struct *vma; 1991499a4f3eSOleg Nesterov 1992499a4f3eSOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 1993499a4f3eSOleg Nesterov if (!valid_vma(vma, false)) 1994499a4f3eSOleg Nesterov continue; 1995499a4f3eSOleg Nesterov /* 1996499a4f3eSOleg Nesterov * This is not strictly accurate, we can race with 1997499a4f3eSOleg Nesterov * uprobe_unregister() and see the already removed 1998499a4f3eSOleg Nesterov * uprobe if delete_uprobe() was not yet called. 199963633cbfSOleg Nesterov * Or this uprobe can be filtered out. 2000499a4f3eSOleg Nesterov */ 2001499a4f3eSOleg Nesterov if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) 2002499a4f3eSOleg Nesterov return; 2003499a4f3eSOleg Nesterov } 2004499a4f3eSOleg Nesterov 2005499a4f3eSOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 2006499a4f3eSOleg Nesterov } 2007499a4f3eSOleg Nesterov 20080908ad6eSAnanth N Mavinakayanahalli static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) 2009ec75fba9SOleg Nesterov { 2010ec75fba9SOleg Nesterov struct page *page; 2011ec75fba9SOleg Nesterov uprobe_opcode_t opcode; 2012ec75fba9SOleg Nesterov int result; 2013ec75fba9SOleg Nesterov 2014013b2debSOleg Nesterov if (WARN_ON_ONCE(!IS_ALIGNED(vaddr, UPROBE_SWBP_INSN_SIZE))) 2015013b2debSOleg Nesterov return -EINVAL; 2016013b2debSOleg Nesterov 2017ec75fba9SOleg Nesterov pagefault_disable(); 2018bd28b145SLinus Torvalds result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr); 2019ec75fba9SOleg Nesterov pagefault_enable(); 2020ec75fba9SOleg Nesterov 2021ec75fba9SOleg Nesterov if (likely(result == 0)) 2022ec75fba9SOleg Nesterov goto out; 2023ec75fba9SOleg Nesterov 20241e987790SDave Hansen /* 20251e987790SDave Hansen * The NULL 'tsk' here ensures that any faults that occur here 20261e987790SDave Hansen * will not be accounted to the task. 'mm' *is* current->mm, 20271e987790SDave Hansen * but we treat this as a 'remote' access since it is 20281e987790SDave Hansen * essentially a kernel access to the memory. 20291e987790SDave Hansen */ 203064019a2eSPeter Xu result = get_user_pages_remote(mm, vaddr, 1, FOLL_FORCE, &page, 20315b56d49fSLorenzo Stoakes NULL, NULL); 2032ec75fba9SOleg Nesterov if (result < 0) 2033ec75fba9SOleg Nesterov return result; 2034ec75fba9SOleg Nesterov 2035ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 2036ec75fba9SOleg Nesterov put_page(page); 2037ec75fba9SOleg Nesterov out: 20380908ad6eSAnanth N Mavinakayanahalli /* This needs to return true for any variant of the trap insn */ 20390908ad6eSAnanth N Mavinakayanahalli return is_trap_insn(&opcode); 2040ec75fba9SOleg Nesterov } 2041ec75fba9SOleg Nesterov 2042d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 20430326f5a9SSrikar Dronamraju { 20443a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 20453a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 20460326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 20470326f5a9SSrikar Dronamraju 2048d8ed45c5SMichel Lespinasse mmap_read_lock(mm); 20490326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 20503a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 20513a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 2052f281769eSOleg Nesterov struct inode *inode = file_inode(vma->vm_file); 2053cb113b47SOleg Nesterov loff_t offset = vaddr_to_offset(vma, bp_vaddr); 20540326f5a9SSrikar Dronamraju 20550326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 20560326f5a9SSrikar Dronamraju } 2057d790d346SOleg Nesterov 2058d790d346SOleg Nesterov if (!uprobe) 20590908ad6eSAnanth N Mavinakayanahalli *is_swbp = is_trap_at_addr(mm, bp_vaddr); 2060d790d346SOleg Nesterov } else { 2061d790d346SOleg Nesterov *is_swbp = -EFAULT; 20623a9ea052SOleg Nesterov } 2063499a4f3eSOleg Nesterov 2064499a4f3eSOleg Nesterov if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) 2065499a4f3eSOleg Nesterov mmf_recalc_uprobes(mm); 2066d8ed45c5SMichel Lespinasse mmap_read_unlock(mm); 20670326f5a9SSrikar Dronamraju 20683a9ea052SOleg Nesterov return uprobe; 20693a9ea052SOleg Nesterov } 20703a9ea052SOleg Nesterov 2071da1816b1SOleg Nesterov static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 2072da1816b1SOleg Nesterov { 2073da1816b1SOleg Nesterov struct uprobe_consumer *uc; 2074da1816b1SOleg Nesterov int remove = UPROBE_HANDLER_REMOVE; 20750dfd0eb8SAnton Arapov bool need_prep = false; /* prepare return uprobe, when needed */ 2076da1816b1SOleg Nesterov 2077da1816b1SOleg Nesterov down_read(&uprobe->register_rwsem); 2078da1816b1SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 2079ea024870SAnton Arapov int rc = 0; 2080da1816b1SOleg Nesterov 2081ea024870SAnton Arapov if (uc->handler) { 2082ea024870SAnton Arapov rc = uc->handler(uc, regs); 2083da1816b1SOleg Nesterov WARN(rc & ~UPROBE_HANDLER_MASK, 2084d75f773cSSakari Ailus "bad rc=0x%x from %ps()\n", rc, uc->handler); 2085ea024870SAnton Arapov } 20860dfd0eb8SAnton Arapov 20870dfd0eb8SAnton Arapov if (uc->ret_handler) 20880dfd0eb8SAnton Arapov need_prep = true; 20890dfd0eb8SAnton Arapov 2090da1816b1SOleg Nesterov remove &= rc; 2091da1816b1SOleg Nesterov } 2092da1816b1SOleg Nesterov 20930dfd0eb8SAnton Arapov if (need_prep && !remove) 20940dfd0eb8SAnton Arapov prepare_uretprobe(uprobe, regs); /* put bp at return */ 20950dfd0eb8SAnton Arapov 2096da1816b1SOleg Nesterov if (remove && uprobe->consumers) { 2097da1816b1SOleg Nesterov WARN_ON(!uprobe_is_active(uprobe)); 2098da1816b1SOleg Nesterov unapply_uprobe(uprobe, current->mm); 2099da1816b1SOleg Nesterov } 2100da1816b1SOleg Nesterov up_read(&uprobe->register_rwsem); 2101da1816b1SOleg Nesterov } 2102da1816b1SOleg Nesterov 2103fec8898dSAnton Arapov static void 2104fec8898dSAnton Arapov handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) 2105fec8898dSAnton Arapov { 2106fec8898dSAnton Arapov struct uprobe *uprobe = ri->uprobe; 2107fec8898dSAnton Arapov struct uprobe_consumer *uc; 2108fec8898dSAnton Arapov 2109fec8898dSAnton Arapov down_read(&uprobe->register_rwsem); 2110fec8898dSAnton Arapov for (uc = uprobe->consumers; uc; uc = uc->next) { 2111fec8898dSAnton Arapov if (uc->ret_handler) 2112fec8898dSAnton Arapov uc->ret_handler(uc, ri->func, regs); 2113fec8898dSAnton Arapov } 2114fec8898dSAnton Arapov up_read(&uprobe->register_rwsem); 2115fec8898dSAnton Arapov } 2116fec8898dSAnton Arapov 2117a83cfeb9SOleg Nesterov static struct return_instance *find_next_ret_chain(struct return_instance *ri) 2118a83cfeb9SOleg Nesterov { 2119a83cfeb9SOleg Nesterov bool chained; 2120a83cfeb9SOleg Nesterov 2121a83cfeb9SOleg Nesterov do { 2122a83cfeb9SOleg Nesterov chained = ri->chained; 2123a83cfeb9SOleg Nesterov ri = ri->next; /* can't be NULL if chained */ 2124a83cfeb9SOleg Nesterov } while (chained); 2125a83cfeb9SOleg Nesterov 2126a83cfeb9SOleg Nesterov return ri; 2127a83cfeb9SOleg Nesterov } 2128a83cfeb9SOleg Nesterov 21290b5256c7SOleg Nesterov static void handle_trampoline(struct pt_regs *regs) 2130fec8898dSAnton Arapov { 2131fec8898dSAnton Arapov struct uprobe_task *utask; 2132a83cfeb9SOleg Nesterov struct return_instance *ri, *next; 21335eeb50deSOleg Nesterov bool valid; 2134fec8898dSAnton Arapov 2135fec8898dSAnton Arapov utask = current->utask; 2136fec8898dSAnton Arapov if (!utask) 21370b5256c7SOleg Nesterov goto sigill; 2138fec8898dSAnton Arapov 2139fec8898dSAnton Arapov ri = utask->return_instances; 2140fec8898dSAnton Arapov if (!ri) 21410b5256c7SOleg Nesterov goto sigill; 2142fec8898dSAnton Arapov 21435eeb50deSOleg Nesterov do { 2144fec8898dSAnton Arapov /* 21455eeb50deSOleg Nesterov * We should throw out the frames invalidated by longjmp(). 21465eeb50deSOleg Nesterov * If this chain is valid, then the next one should be alive 21475eeb50deSOleg Nesterov * or NULL; the latter case means that nobody but ri->func 21485eeb50deSOleg Nesterov * could hit this trampoline on return. TODO: sigaltstack(). 2149fec8898dSAnton Arapov */ 21505eeb50deSOleg Nesterov next = find_next_ret_chain(ri); 215186dcb702SOleg Nesterov valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs); 21525eeb50deSOleg Nesterov 2153fec8898dSAnton Arapov instruction_pointer_set(regs, ri->orig_ret_vaddr); 2154a83cfeb9SOleg Nesterov do { 21555eeb50deSOleg Nesterov if (valid) 2156fec8898dSAnton Arapov handle_uretprobe_chain(ri, regs); 21572bb5e840SOleg Nesterov ri = free_ret_instance(ri); 2158878b5a6eSOleg Nesterov utask->depth--; 2159a83cfeb9SOleg Nesterov } while (ri != next); 21605eeb50deSOleg Nesterov } while (!valid); 2161fec8898dSAnton Arapov 2162fec8898dSAnton Arapov utask->return_instances = ri; 21630b5256c7SOleg Nesterov return; 2164fec8898dSAnton Arapov 21650b5256c7SOleg Nesterov sigill: 21660b5256c7SOleg Nesterov uprobe_warn(current, "handle uretprobe, sending SIGILL."); 21673cf5d076SEric W. Biederman force_sig(SIGILL); 21680b5256c7SOleg Nesterov 2169fec8898dSAnton Arapov } 2170fec8898dSAnton Arapov 21716fe50a28SDavid A. Long bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) 21726fe50a28SDavid A. Long { 21736fe50a28SDavid A. Long return false; 21746fe50a28SDavid A. Long } 21756fe50a28SDavid A. Long 217686dcb702SOleg Nesterov bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, 217786dcb702SOleg Nesterov struct pt_regs *regs) 217897da8976SOleg Nesterov { 217997da8976SOleg Nesterov return true; 218097da8976SOleg Nesterov } 218197da8976SOleg Nesterov 21823a9ea052SOleg Nesterov /* 21833a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 21843a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 21853a9ea052SOleg Nesterov */ 21863a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 21873a9ea052SOleg Nesterov { 21883a9ea052SOleg Nesterov struct uprobe *uprobe; 21893a9ea052SOleg Nesterov unsigned long bp_vaddr; 21903f649ab7SKees Cook int is_swbp; 21913a9ea052SOleg Nesterov 21923a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 21930b5256c7SOleg Nesterov if (bp_vaddr == get_trampoline_vaddr()) 21940b5256c7SOleg Nesterov return handle_trampoline(regs); 2195fec8898dSAnton Arapov 2196fec8898dSAnton Arapov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 21970326f5a9SSrikar Dronamraju if (!uprobe) { 219856bb4cf6SOleg Nesterov if (is_swbp > 0) { 21990326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 2200fe5ed7abSOleg Nesterov force_sig(SIGTRAP); 220156bb4cf6SOleg Nesterov } else { 220256bb4cf6SOleg Nesterov /* 220356bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 220456bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 220556bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 220656bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 220756bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 220856bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 220956bb4cf6SOleg Nesterov */ 221056bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 221156bb4cf6SOleg Nesterov } 22120326f5a9SSrikar Dronamraju return; 22130326f5a9SSrikar Dronamraju } 221474e59dfcSOleg Nesterov 221574e59dfcSOleg Nesterov /* change it in advance for ->handler() and restart */ 221674e59dfcSOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 221774e59dfcSOleg Nesterov 2218142b18ddSOleg Nesterov /* 2219142b18ddSOleg Nesterov * TODO: move copy_insn/etc into _register and remove this hack. 2220142b18ddSOleg Nesterov * After we hit the bp, _unregister + _register can install the 2221142b18ddSOleg Nesterov * new and not-yet-analyzed uprobe at the same address, restart. 2222142b18ddSOleg Nesterov */ 222371434f2fSOleg Nesterov if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) 222474e59dfcSOleg Nesterov goto out; 22250326f5a9SSrikar Dronamraju 222609d3f015SAndrea Parri /* 222709d3f015SAndrea Parri * Pairs with the smp_wmb() in prepare_uprobe(). 222809d3f015SAndrea Parri * 222909d3f015SAndrea Parri * Guarantees that if we see the UPROBE_COPY_INSN bit set, then 223009d3f015SAndrea Parri * we must also see the stores to &uprobe->arch performed by the 223109d3f015SAndrea Parri * prepare_uprobe() call. 223209d3f015SAndrea Parri */ 223309d3f015SAndrea Parri smp_rmb(); 223409d3f015SAndrea Parri 223572fd293aSOleg Nesterov /* Tracing handlers use ->utask to communicate with fetch methods */ 223672fd293aSOleg Nesterov if (!get_utask()) 223772fd293aSOleg Nesterov goto out; 223872fd293aSOleg Nesterov 22396fe50a28SDavid A. Long if (arch_uprobe_ignore(&uprobe->arch, regs)) 22406fe50a28SDavid A. Long goto out; 22416fe50a28SDavid A. Long 22420326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 22436fe50a28SDavid A. Long 22448a6b1732SOleg Nesterov if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 22450578a970SOleg Nesterov goto out; 22460326f5a9SSrikar Dronamraju 2247608e7427SOleg Nesterov if (!pre_ssout(uprobe, regs, bp_vaddr)) 22480326f5a9SSrikar Dronamraju return; 22490326f5a9SSrikar Dronamraju 22508a6b1732SOleg Nesterov /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ 22510578a970SOleg Nesterov out: 22520326f5a9SSrikar Dronamraju put_uprobe(uprobe); 22530326f5a9SSrikar Dronamraju } 22540326f5a9SSrikar Dronamraju 22550326f5a9SSrikar Dronamraju /* 22560326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 22570326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 22580326f5a9SSrikar Dronamraju */ 22590326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 22600326f5a9SSrikar Dronamraju { 22610326f5a9SSrikar Dronamraju struct uprobe *uprobe; 2262014940baSOleg Nesterov int err = 0; 22630326f5a9SSrikar Dronamraju 22640326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 22650326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 2266014940baSOleg Nesterov err = arch_uprobe_post_xol(&uprobe->arch, regs); 22670326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 22680326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 22690326f5a9SSrikar Dronamraju else 22700326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 22710326f5a9SSrikar Dronamraju 22720326f5a9SSrikar Dronamraju put_uprobe(uprobe); 22730326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 22740326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 2275d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 22760326f5a9SSrikar Dronamraju 22770326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 22780326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 22790326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 2280014940baSOleg Nesterov 2281014940baSOleg Nesterov if (unlikely(err)) { 2282014940baSOleg Nesterov uprobe_warn(current, "execute the probed insn, sending SIGILL."); 22833cf5d076SEric W. Biederman force_sig(SIGILL); 2284014940baSOleg Nesterov } 22850326f5a9SSrikar Dronamraju } 22860326f5a9SSrikar Dronamraju 22870326f5a9SSrikar Dronamraju /* 22881b08e907SOleg Nesterov * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and 22891b08e907SOleg Nesterov * allows the thread to return from interrupt. After that handle_swbp() 22901b08e907SOleg Nesterov * sets utask->active_uprobe. 22910326f5a9SSrikar Dronamraju * 22921b08e907SOleg Nesterov * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag 22931b08e907SOleg Nesterov * and allows the thread to return from interrupt. 22940326f5a9SSrikar Dronamraju * 22950326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 22960326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 22970326f5a9SSrikar Dronamraju */ 22980326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 22990326f5a9SSrikar Dronamraju { 23000326f5a9SSrikar Dronamraju struct uprobe_task *utask; 23010326f5a9SSrikar Dronamraju 2302db023ea5SOleg Nesterov clear_thread_flag(TIF_UPROBE); 2303db023ea5SOleg Nesterov 23040326f5a9SSrikar Dronamraju utask = current->utask; 23051b08e907SOleg Nesterov if (utask && utask->active_uprobe) 23060326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 23071b08e907SOleg Nesterov else 23081b08e907SOleg Nesterov handle_swbp(regs); 23090326f5a9SSrikar Dronamraju } 23100326f5a9SSrikar Dronamraju 23110326f5a9SSrikar Dronamraju /* 23120326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 23130326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 23140326f5a9SSrikar Dronamraju */ 23150326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 23160326f5a9SSrikar Dronamraju { 23170dfd0eb8SAnton Arapov if (!current->mm) 23180dfd0eb8SAnton Arapov return 0; 23190dfd0eb8SAnton Arapov 23200dfd0eb8SAnton Arapov if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && 23210dfd0eb8SAnton Arapov (!current->utask || !current->utask->return_instances)) 23220326f5a9SSrikar Dronamraju return 0; 23230326f5a9SSrikar Dronamraju 23240326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 23250326f5a9SSrikar Dronamraju return 1; 23260326f5a9SSrikar Dronamraju } 23270326f5a9SSrikar Dronamraju 23280326f5a9SSrikar Dronamraju /* 23290326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 23300326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 23310326f5a9SSrikar Dronamraju */ 23320326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 23330326f5a9SSrikar Dronamraju { 23340326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 23350326f5a9SSrikar Dronamraju 23360326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 23370326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 23380326f5a9SSrikar Dronamraju return 0; 23390326f5a9SSrikar Dronamraju 23400326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 23410326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 23420326f5a9SSrikar Dronamraju return 1; 23430326f5a9SSrikar Dronamraju } 23440326f5a9SSrikar Dronamraju 23450326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 23460326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 23470326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 23480326f5a9SSrikar Dronamraju }; 23490326f5a9SSrikar Dronamraju 2350aad42dd4SNadav Amit void __init uprobes_init(void) 2351a5f4374aSIngo Molnar { 2352a5f4374aSIngo Molnar int i; 2353a5f4374aSIngo Molnar 235466d06dffSOleg Nesterov for (i = 0; i < UPROBES_HASH_SZ; i++) 2355a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 23560326f5a9SSrikar Dronamraju 2357aad42dd4SNadav Amit BUG_ON(register_die_notifier(&uprobe_exception_nb)); 2358a5f4374aSIngo Molnar } 2359