1a5f4374aSIngo Molnar /* 2a5f4374aSIngo Molnar * User-space Probes (UProbes) 3a5f4374aSIngo Molnar * 4a5f4374aSIngo Molnar * This program is free software; you can redistribute it and/or modify 5a5f4374aSIngo Molnar * it under the terms of the GNU General Public License as published by 6a5f4374aSIngo Molnar * the Free Software Foundation; either version 2 of the License, or 7a5f4374aSIngo Molnar * (at your option) any later version. 8a5f4374aSIngo Molnar * 9a5f4374aSIngo Molnar * This program is distributed in the hope that it will be useful, 10a5f4374aSIngo Molnar * but WITHOUT ANY WARRANTY; without even the implied warranty of 11a5f4374aSIngo Molnar * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12a5f4374aSIngo Molnar * GNU General Public License for more details. 13a5f4374aSIngo Molnar * 14a5f4374aSIngo Molnar * You should have received a copy of the GNU General Public License 15a5f4374aSIngo Molnar * along with this program; if not, write to the Free Software 16a5f4374aSIngo Molnar * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 17a5f4374aSIngo Molnar * 1835aa621bSIngo Molnar * Copyright (C) IBM Corporation, 2008-2012 19a5f4374aSIngo Molnar * Authors: 20a5f4374aSIngo Molnar * Srikar Dronamraju 21a5f4374aSIngo Molnar * Jim Keniston 2235aa621bSIngo Molnar * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> 23a5f4374aSIngo Molnar */ 24a5f4374aSIngo Molnar 25a5f4374aSIngo Molnar #include <linux/kernel.h> 26a5f4374aSIngo Molnar #include <linux/highmem.h> 27a5f4374aSIngo Molnar #include <linux/pagemap.h> /* read_mapping_page */ 28a5f4374aSIngo Molnar #include <linux/slab.h> 29a5f4374aSIngo Molnar #include <linux/sched.h> 30e8440c14SJosh Stone #include <linux/export.h> 31a5f4374aSIngo Molnar #include <linux/rmap.h> /* anon_vma_prepare */ 32a5f4374aSIngo Molnar #include <linux/mmu_notifier.h> /* set_pte_at_notify */ 33a5f4374aSIngo Molnar #include <linux/swap.h> /* try_to_free_swap */ 340326f5a9SSrikar Dronamraju #include <linux/ptrace.h> /* user_enable_single_step */ 350326f5a9SSrikar Dronamraju #include <linux/kdebug.h> /* notifier mechanism */ 36194f8dcbSOleg Nesterov #include "../../mm/internal.h" /* munlock_vma_page */ 3732cdba1eSOleg Nesterov #include <linux/percpu-rwsem.h> 38aa59c53fSOleg Nesterov #include <linux/task_work.h> 3940814f68SOleg Nesterov #include <linux/shmem_fs.h> 40a5f4374aSIngo Molnar 41a5f4374aSIngo Molnar #include <linux/uprobes.h> 42a5f4374aSIngo Molnar 43d4b3b638SSrikar Dronamraju #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) 44d4b3b638SSrikar Dronamraju #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE 45d4b3b638SSrikar Dronamraju 46a5f4374aSIngo Molnar static struct rb_root uprobes_tree = RB_ROOT; 47441f1eb7SOleg Nesterov /* 48441f1eb7SOleg Nesterov * allows us to skip the uprobe_mmap if there are no uprobe events active 49441f1eb7SOleg Nesterov * at this time. Probably a fine grained per inode count is better? 50441f1eb7SOleg Nesterov */ 51441f1eb7SOleg Nesterov #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) 52a5f4374aSIngo Molnar 53a5f4374aSIngo Molnar static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ 54a5f4374aSIngo Molnar 55a5f4374aSIngo Molnar #define UPROBES_HASH_SZ 13 56a5f4374aSIngo Molnar /* serialize uprobe->pending_list */ 57a5f4374aSIngo Molnar static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; 58a5f4374aSIngo Molnar #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 59a5f4374aSIngo Molnar 6032cdba1eSOleg Nesterov static struct percpu_rw_semaphore dup_mmap_sem; 6132cdba1eSOleg Nesterov 62cb9a19feSOleg Nesterov /* Have a copy of original instruction */ 6371434f2fSOleg Nesterov #define UPROBE_COPY_INSN 0 64cb9a19feSOleg Nesterov 653ff54efdSSrikar Dronamraju struct uprobe { 663ff54efdSSrikar Dronamraju struct rb_node rb_node; /* node in the rb tree */ 673ff54efdSSrikar Dronamraju atomic_t ref; 68e591c8d7SOleg Nesterov struct rw_semaphore register_rwsem; 693ff54efdSSrikar Dronamraju struct rw_semaphore consumer_rwsem; 703ff54efdSSrikar Dronamraju struct list_head pending_list; 713ff54efdSSrikar Dronamraju struct uprobe_consumer *consumers; 723ff54efdSSrikar Dronamraju struct inode *inode; /* Also hold a ref to inode */ 733ff54efdSSrikar Dronamraju loff_t offset; 7471434f2fSOleg Nesterov unsigned long flags; 75ad439356SOleg Nesterov 76ad439356SOleg Nesterov /* 77ad439356SOleg Nesterov * The generic code assumes that it has two members of unknown type 78ad439356SOleg Nesterov * owned by the arch-specific code: 79ad439356SOleg Nesterov * 80ad439356SOleg Nesterov * insn - copy_insn() saves the original instruction here for 81ad439356SOleg Nesterov * arch_uprobe_analyze_insn(). 82ad439356SOleg Nesterov * 83ad439356SOleg Nesterov * ixol - potentially modified instruction to execute out of 84ad439356SOleg Nesterov * line, copied to xol_area by xol_get_insn_slot(). 85ad439356SOleg Nesterov */ 863ff54efdSSrikar Dronamraju struct arch_uprobe arch; 873ff54efdSSrikar Dronamraju }; 883ff54efdSSrikar Dronamraju 890dfd0eb8SAnton Arapov struct return_instance { 900dfd0eb8SAnton Arapov struct uprobe *uprobe; 910dfd0eb8SAnton Arapov unsigned long func; 920dfd0eb8SAnton Arapov unsigned long orig_ret_vaddr; /* original return address */ 930dfd0eb8SAnton Arapov bool chained; /* true, if instance is nested */ 940dfd0eb8SAnton Arapov 950dfd0eb8SAnton Arapov struct return_instance *next; /* keep as stack */ 960dfd0eb8SAnton Arapov }; 970dfd0eb8SAnton Arapov 98a5f4374aSIngo Molnar /* 99ad439356SOleg Nesterov * Execute out of line area: anonymous executable mapping installed 100ad439356SOleg Nesterov * by the probed task to execute the copy of the original instruction 101ad439356SOleg Nesterov * mangled by set_swbp(). 102ad439356SOleg Nesterov * 103c912dae6SOleg Nesterov * On a breakpoint hit, thread contests for a slot. It frees the 104c912dae6SOleg Nesterov * slot after singlestep. Currently a fixed number of slots are 105c912dae6SOleg Nesterov * allocated. 106c912dae6SOleg Nesterov */ 107c912dae6SOleg Nesterov struct xol_area { 108c912dae6SOleg Nesterov wait_queue_head_t wq; /* if all slots are busy */ 109c912dae6SOleg Nesterov atomic_t slot_count; /* number of in-use slots */ 110c912dae6SOleg Nesterov unsigned long *bitmap; /* 0 = free slot */ 111c912dae6SOleg Nesterov struct page *page; 112c912dae6SOleg Nesterov 113c912dae6SOleg Nesterov /* 114c912dae6SOleg Nesterov * We keep the vma's vm_start rather than a pointer to the vma 115c912dae6SOleg Nesterov * itself. The probed process or a naughty kernel module could make 116c912dae6SOleg Nesterov * the vma go away, and we must handle that reasonably gracefully. 117c912dae6SOleg Nesterov */ 118c912dae6SOleg Nesterov unsigned long vaddr; /* Page(s) of instruction slots */ 119c912dae6SOleg Nesterov }; 120c912dae6SOleg Nesterov 121c912dae6SOleg Nesterov /* 122a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 123a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 124a5f4374aSIngo Molnar * changed after breakpoint was inserted. 125a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 126a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 127a5f4374aSIngo Molnar * executable vma. 128a5f4374aSIngo Molnar */ 129a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 130a5f4374aSIngo Molnar { 13113f59c5eSOleg Nesterov vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; 132a5f4374aSIngo Molnar 133e40cfce6SOleg Nesterov if (is_register) 134e40cfce6SOleg Nesterov flags |= VM_WRITE; 135a5f4374aSIngo Molnar 136e40cfce6SOleg Nesterov return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; 137a5f4374aSIngo Molnar } 138a5f4374aSIngo Molnar 13957683f72SOleg Nesterov static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) 140a5f4374aSIngo Molnar { 14157683f72SOleg Nesterov return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); 142a5f4374aSIngo Molnar } 143a5f4374aSIngo Molnar 144cb113b47SOleg Nesterov static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) 145cb113b47SOleg Nesterov { 146cb113b47SOleg Nesterov return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); 147cb113b47SOleg Nesterov } 148cb113b47SOleg Nesterov 149a5f4374aSIngo Molnar /** 150a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 151a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 152a5f4374aSIngo Molnar * 153a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 154c517ee74SOleg Nesterov * @addr: address the old @page is mapped at 155a5f4374aSIngo Molnar * @page: the cowed page we are replacing by kpage 156a5f4374aSIngo Molnar * @kpage: the modified page we replace page by 157a5f4374aSIngo Molnar * 158a5f4374aSIngo Molnar * Returns 0 on success, -EFAULT on failure. 159a5f4374aSIngo Molnar */ 160c517ee74SOleg Nesterov static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 161c517ee74SOleg Nesterov struct page *page, struct page *kpage) 162a5f4374aSIngo Molnar { 163a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 1645323ce71SOleg Nesterov spinlock_t *ptl; 1655323ce71SOleg Nesterov pte_t *ptep; 1669f92448cSOleg Nesterov int err; 1676bdb913fSHaggai Eran /* For mmu_notifiers */ 1686bdb913fSHaggai Eran const unsigned long mmun_start = addr; 1696bdb913fSHaggai Eran const unsigned long mmun_end = addr + PAGE_SIZE; 17000501b53SJohannes Weiner struct mem_cgroup *memcg; 17100501b53SJohannes Weiner 17200501b53SJohannes Weiner err = mem_cgroup_try_charge(kpage, vma->vm_mm, GFP_KERNEL, &memcg); 17300501b53SJohannes Weiner if (err) 17400501b53SJohannes Weiner return err; 175a5f4374aSIngo Molnar 176194f8dcbSOleg Nesterov /* For try_to_free_swap() and munlock_vma_page() below */ 1779f92448cSOleg Nesterov lock_page(page); 1789f92448cSOleg Nesterov 1796bdb913fSHaggai Eran mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 1809f92448cSOleg Nesterov err = -EAGAIN; 1815323ce71SOleg Nesterov ptep = page_check_address(page, mm, addr, &ptl, 0); 182a5f4374aSIngo Molnar if (!ptep) 1839f92448cSOleg Nesterov goto unlock; 184a5f4374aSIngo Molnar 185a5f4374aSIngo Molnar get_page(kpage); 186a5f4374aSIngo Molnar page_add_new_anon_rmap(kpage, vma, addr); 18700501b53SJohannes Weiner mem_cgroup_commit_charge(kpage, memcg, false); 18800501b53SJohannes Weiner lru_cache_add_active_or_unevictable(kpage, vma); 189a5f4374aSIngo Molnar 1907396fa81SSrikar Dronamraju if (!PageAnon(page)) { 1917396fa81SSrikar Dronamraju dec_mm_counter(mm, MM_FILEPAGES); 1927396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1937396fa81SSrikar Dronamraju } 1947396fa81SSrikar Dronamraju 195a5f4374aSIngo Molnar flush_cache_page(vma, addr, pte_pfn(*ptep)); 19634ee645eSJoerg Roedel ptep_clear_flush_notify(vma, addr, ptep); 197a5f4374aSIngo Molnar set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); 198a5f4374aSIngo Molnar 199a5f4374aSIngo Molnar page_remove_rmap(page); 200a5f4374aSIngo Molnar if (!page_mapped(page)) 201a5f4374aSIngo Molnar try_to_free_swap(page); 202a5f4374aSIngo Molnar pte_unmap_unlock(ptep, ptl); 203a5f4374aSIngo Molnar 204194f8dcbSOleg Nesterov if (vma->vm_flags & VM_LOCKED) 205194f8dcbSOleg Nesterov munlock_vma_page(page); 206194f8dcbSOleg Nesterov put_page(page); 207194f8dcbSOleg Nesterov 2089f92448cSOleg Nesterov err = 0; 2099f92448cSOleg Nesterov unlock: 21000501b53SJohannes Weiner mem_cgroup_cancel_charge(kpage, memcg); 2116bdb913fSHaggai Eran mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 2129f92448cSOleg Nesterov unlock_page(page); 2139f92448cSOleg Nesterov return err; 214a5f4374aSIngo Molnar } 215a5f4374aSIngo Molnar 216a5f4374aSIngo Molnar /** 2175cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 218a5f4374aSIngo Molnar * @insn: instruction to be checked. 2195cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 220a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 221a5f4374aSIngo Molnar */ 2225cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 223a5f4374aSIngo Molnar { 2245cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 225a5f4374aSIngo Molnar } 226a5f4374aSIngo Molnar 2270908ad6eSAnanth N Mavinakayanahalli /** 2280908ad6eSAnanth N Mavinakayanahalli * is_trap_insn - check if instruction is breakpoint instruction. 2290908ad6eSAnanth N Mavinakayanahalli * @insn: instruction to be checked. 2300908ad6eSAnanth N Mavinakayanahalli * Default implementation of is_trap_insn 2310908ad6eSAnanth N Mavinakayanahalli * Returns true if @insn is a breakpoint instruction. 2320908ad6eSAnanth N Mavinakayanahalli * 2330908ad6eSAnanth N Mavinakayanahalli * This function is needed for the case where an architecture has multiple 2340908ad6eSAnanth N Mavinakayanahalli * trap instructions (like powerpc). 2350908ad6eSAnanth N Mavinakayanahalli */ 2360908ad6eSAnanth N Mavinakayanahalli bool __weak is_trap_insn(uprobe_opcode_t *insn) 2370908ad6eSAnanth N Mavinakayanahalli { 2380908ad6eSAnanth N Mavinakayanahalli return is_swbp_insn(insn); 2390908ad6eSAnanth N Mavinakayanahalli } 2400908ad6eSAnanth N Mavinakayanahalli 241ab0d805cSOleg Nesterov static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) 242cceb55aaSOleg Nesterov { 243cceb55aaSOleg Nesterov void *kaddr = kmap_atomic(page); 244ab0d805cSOleg Nesterov memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); 245cceb55aaSOleg Nesterov kunmap_atomic(kaddr); 246cceb55aaSOleg Nesterov } 247cceb55aaSOleg Nesterov 2485669cceeSOleg Nesterov static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) 2495669cceeSOleg Nesterov { 2505669cceeSOleg Nesterov void *kaddr = kmap_atomic(page); 2515669cceeSOleg Nesterov memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); 2525669cceeSOleg Nesterov kunmap_atomic(kaddr); 2535669cceeSOleg Nesterov } 2545669cceeSOleg Nesterov 255ed6f6a50SOleg Nesterov static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) 256ed6f6a50SOleg Nesterov { 257ed6f6a50SOleg Nesterov uprobe_opcode_t old_opcode; 258ed6f6a50SOleg Nesterov bool is_swbp; 259ed6f6a50SOleg Nesterov 2600908ad6eSAnanth N Mavinakayanahalli /* 2610908ad6eSAnanth N Mavinakayanahalli * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. 2620908ad6eSAnanth N Mavinakayanahalli * We do not check if it is any other 'trap variant' which could 2630908ad6eSAnanth N Mavinakayanahalli * be conditional trap instruction such as the one powerpc supports. 2640908ad6eSAnanth N Mavinakayanahalli * 2650908ad6eSAnanth N Mavinakayanahalli * The logic is that we do not care if the underlying instruction 2660908ad6eSAnanth N Mavinakayanahalli * is a trap variant; uprobes always wins over any other (gdb) 2670908ad6eSAnanth N Mavinakayanahalli * breakpoint. 2680908ad6eSAnanth N Mavinakayanahalli */ 269ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); 270ed6f6a50SOleg Nesterov is_swbp = is_swbp_insn(&old_opcode); 271ed6f6a50SOleg Nesterov 272ed6f6a50SOleg Nesterov if (is_swbp_insn(new_opcode)) { 273ed6f6a50SOleg Nesterov if (is_swbp) /* register: already installed? */ 274ed6f6a50SOleg Nesterov return 0; 275ed6f6a50SOleg Nesterov } else { 276ed6f6a50SOleg Nesterov if (!is_swbp) /* unregister: was it changed by us? */ 277076a365bSOleg Nesterov return 0; 278ed6f6a50SOleg Nesterov } 279ed6f6a50SOleg Nesterov 280ed6f6a50SOleg Nesterov return 1; 281ed6f6a50SOleg Nesterov } 282ed6f6a50SOleg Nesterov 283a5f4374aSIngo Molnar /* 284a5f4374aSIngo Molnar * NOTE: 285a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 286a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 287a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 2880908ad6eSAnanth N Mavinakayanahalli * supported by that architecture then we need to modify is_trap_at_addr and 289f72d41faSOleg Nesterov * uprobe_write_opcode accordingly. This would never be a problem for archs 290f72d41faSOleg Nesterov * that have fixed length instructions. 29129dedee0SOleg Nesterov * 292f72d41faSOleg Nesterov * uprobe_write_opcode - write the opcode at a given virtual address. 293a5f4374aSIngo Molnar * @mm: the probed process address space. 294a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 295a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 296a5f4374aSIngo Molnar * 29729dedee0SOleg Nesterov * Called with mm->mmap_sem held for write. 298a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 299a5f4374aSIngo Molnar */ 300f72d41faSOleg Nesterov int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, 301cceb55aaSOleg Nesterov uprobe_opcode_t opcode) 302a5f4374aSIngo Molnar { 303a5f4374aSIngo Molnar struct page *old_page, *new_page; 304a5f4374aSIngo Molnar struct vm_area_struct *vma; 305a5f4374aSIngo Molnar int ret; 306f403072cSOleg Nesterov 3075323ce71SOleg Nesterov retry: 308a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 30975ed82eaSOleg Nesterov ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); 310a5f4374aSIngo Molnar if (ret <= 0) 311a5f4374aSIngo Molnar return ret; 312a5f4374aSIngo Molnar 313ed6f6a50SOleg Nesterov ret = verify_opcode(old_page, vaddr, &opcode); 314ed6f6a50SOleg Nesterov if (ret <= 0) 315ed6f6a50SOleg Nesterov goto put_old; 316ed6f6a50SOleg Nesterov 31729dedee0SOleg Nesterov ret = anon_vma_prepare(vma); 31829dedee0SOleg Nesterov if (ret) 31929dedee0SOleg Nesterov goto put_old; 32029dedee0SOleg Nesterov 321a5f4374aSIngo Molnar ret = -ENOMEM; 322a5f4374aSIngo Molnar new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); 323a5f4374aSIngo Molnar if (!new_page) 3249f92448cSOleg Nesterov goto put_old; 325a5f4374aSIngo Molnar 32629dedee0SOleg Nesterov __SetPageUptodate(new_page); 3273f47107cSOleg Nesterov copy_highpage(new_page, old_page); 3283f47107cSOleg Nesterov copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 329a5f4374aSIngo Molnar 330c517ee74SOleg Nesterov ret = __replace_page(vma, vaddr, old_page, new_page); 331a5f4374aSIngo Molnar page_cache_release(new_page); 3329f92448cSOleg Nesterov put_old: 333a5f4374aSIngo Molnar put_page(old_page); 334a5f4374aSIngo Molnar 3355323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 3365323ce71SOleg Nesterov goto retry; 337a5f4374aSIngo Molnar return ret; 338a5f4374aSIngo Molnar } 339a5f4374aSIngo Molnar 340a5f4374aSIngo Molnar /** 3415cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 342e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 343a5f4374aSIngo Molnar * @mm: the probed process address space. 344a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 345a5f4374aSIngo Molnar * 346a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 347a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 348a5f4374aSIngo Molnar */ 3495cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 350a5f4374aSIngo Molnar { 351f72d41faSOleg Nesterov return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN); 352a5f4374aSIngo Molnar } 353a5f4374aSIngo Molnar 354a5f4374aSIngo Molnar /** 355a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 356a5f4374aSIngo Molnar * @mm: the probed process address space. 357e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 358a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 359a5f4374aSIngo Molnar * 360a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 361a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 362a5f4374aSIngo Molnar */ 363a5f4374aSIngo Molnar int __weak 364ded86e7cSOleg Nesterov set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 365a5f4374aSIngo Molnar { 366803200e2SOleg Nesterov return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn); 367a5f4374aSIngo Molnar } 368a5f4374aSIngo Molnar 369f231722aSOleg Nesterov static struct uprobe *get_uprobe(struct uprobe *uprobe) 370f231722aSOleg Nesterov { 371f231722aSOleg Nesterov atomic_inc(&uprobe->ref); 372f231722aSOleg Nesterov return uprobe; 373f231722aSOleg Nesterov } 374f231722aSOleg Nesterov 375f231722aSOleg Nesterov static void put_uprobe(struct uprobe *uprobe) 376f231722aSOleg Nesterov { 377f231722aSOleg Nesterov if (atomic_dec_and_test(&uprobe->ref)) 378f231722aSOleg Nesterov kfree(uprobe); 379f231722aSOleg Nesterov } 380f231722aSOleg Nesterov 381a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 382a5f4374aSIngo Molnar { 383a5f4374aSIngo Molnar if (l->inode < r->inode) 384a5f4374aSIngo Molnar return -1; 385a5f4374aSIngo Molnar 386a5f4374aSIngo Molnar if (l->inode > r->inode) 387a5f4374aSIngo Molnar return 1; 388a5f4374aSIngo Molnar 389a5f4374aSIngo Molnar if (l->offset < r->offset) 390a5f4374aSIngo Molnar return -1; 391a5f4374aSIngo Molnar 392a5f4374aSIngo Molnar if (l->offset > r->offset) 393a5f4374aSIngo Molnar return 1; 394a5f4374aSIngo Molnar 395a5f4374aSIngo Molnar return 0; 396a5f4374aSIngo Molnar } 397a5f4374aSIngo Molnar 398a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 399a5f4374aSIngo Molnar { 400a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 401a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 402a5f4374aSIngo Molnar struct uprobe *uprobe; 403a5f4374aSIngo Molnar int match; 404a5f4374aSIngo Molnar 405a5f4374aSIngo Molnar while (n) { 406a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 407a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 408f231722aSOleg Nesterov if (!match) 409f231722aSOleg Nesterov return get_uprobe(uprobe); 410a5f4374aSIngo Molnar 411a5f4374aSIngo Molnar if (match < 0) 412a5f4374aSIngo Molnar n = n->rb_left; 413a5f4374aSIngo Molnar else 414a5f4374aSIngo Molnar n = n->rb_right; 415a5f4374aSIngo Molnar } 416a5f4374aSIngo Molnar return NULL; 417a5f4374aSIngo Molnar } 418a5f4374aSIngo Molnar 419a5f4374aSIngo Molnar /* 420a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 421a5f4374aSIngo Molnar * Acquires uprobes_treelock 422a5f4374aSIngo Molnar */ 423a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 424a5f4374aSIngo Molnar { 425a5f4374aSIngo Molnar struct uprobe *uprobe; 426a5f4374aSIngo Molnar 4276f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 428a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 4296f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 430a5f4374aSIngo Molnar 431a5f4374aSIngo Molnar return uprobe; 432a5f4374aSIngo Molnar } 433a5f4374aSIngo Molnar 434a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 435a5f4374aSIngo Molnar { 436a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 437a5f4374aSIngo Molnar struct rb_node *parent = NULL; 438a5f4374aSIngo Molnar struct uprobe *u; 439a5f4374aSIngo Molnar int match; 440a5f4374aSIngo Molnar 441a5f4374aSIngo Molnar while (*p) { 442a5f4374aSIngo Molnar parent = *p; 443a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 444a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 445f231722aSOleg Nesterov if (!match) 446f231722aSOleg Nesterov return get_uprobe(u); 447a5f4374aSIngo Molnar 448a5f4374aSIngo Molnar if (match < 0) 449a5f4374aSIngo Molnar p = &parent->rb_left; 450a5f4374aSIngo Molnar else 451a5f4374aSIngo Molnar p = &parent->rb_right; 452a5f4374aSIngo Molnar 453a5f4374aSIngo Molnar } 454a5f4374aSIngo Molnar 455a5f4374aSIngo Molnar u = NULL; 456a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 457a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 458a5f4374aSIngo Molnar /* get access + creation ref */ 459a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 460a5f4374aSIngo Molnar 461a5f4374aSIngo Molnar return u; 462a5f4374aSIngo Molnar } 463a5f4374aSIngo Molnar 464a5f4374aSIngo Molnar /* 465a5f4374aSIngo Molnar * Acquire uprobes_treelock. 466a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 467a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 468a5f4374aSIngo Molnar * 469a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 470a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 471a5f4374aSIngo Molnar */ 472a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 473a5f4374aSIngo Molnar { 474a5f4374aSIngo Molnar struct uprobe *u; 475a5f4374aSIngo Molnar 4766f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 477a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 4786f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 479a5f4374aSIngo Molnar 480a5f4374aSIngo Molnar return u; 481a5f4374aSIngo Molnar } 482a5f4374aSIngo Molnar 483a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 484a5f4374aSIngo Molnar { 485a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 486a5f4374aSIngo Molnar 487a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 488a5f4374aSIngo Molnar if (!uprobe) 489a5f4374aSIngo Molnar return NULL; 490a5f4374aSIngo Molnar 491a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 492a5f4374aSIngo Molnar uprobe->offset = offset; 493e591c8d7SOleg Nesterov init_rwsem(&uprobe->register_rwsem); 494a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 495a5f4374aSIngo Molnar 496a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 497a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 498a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 499a5f4374aSIngo Molnar if (cur_uprobe) { 500a5f4374aSIngo Molnar kfree(uprobe); 501a5f4374aSIngo Molnar uprobe = cur_uprobe; 502a5f4374aSIngo Molnar iput(inode); 503a5f4374aSIngo Molnar } 504a5f4374aSIngo Molnar 505a5f4374aSIngo Molnar return uprobe; 506a5f4374aSIngo Molnar } 507a5f4374aSIngo Molnar 5089a98e03cSOleg Nesterov static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 509a5f4374aSIngo Molnar { 510a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 511e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 512e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 513a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 514a5f4374aSIngo Molnar } 515a5f4374aSIngo Molnar 516a5f4374aSIngo Molnar /* 517e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 518e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 519a5f4374aSIngo Molnar * or return false. 520a5f4374aSIngo Molnar */ 521e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 522a5f4374aSIngo Molnar { 523a5f4374aSIngo Molnar struct uprobe_consumer **con; 524a5f4374aSIngo Molnar bool ret = false; 525a5f4374aSIngo Molnar 526a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 527a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 528e3343e6aSSrikar Dronamraju if (*con == uc) { 529e3343e6aSSrikar Dronamraju *con = uc->next; 530a5f4374aSIngo Molnar ret = true; 531a5f4374aSIngo Molnar break; 532a5f4374aSIngo Molnar } 533a5f4374aSIngo Molnar } 534a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 535a5f4374aSIngo Molnar 536a5f4374aSIngo Molnar return ret; 537a5f4374aSIngo Molnar } 538a5f4374aSIngo Molnar 5392ded0980SOleg Nesterov static int __copy_insn(struct address_space *mapping, struct file *filp, 5402ded0980SOleg Nesterov void *insn, int nbytes, loff_t offset) 541a5f4374aSIngo Molnar { 542a5f4374aSIngo Molnar struct page *page; 543a5f4374aSIngo Molnar /* 54440814f68SOleg Nesterov * Ensure that the page that has the original instruction is populated 54540814f68SOleg Nesterov * and in page-cache. If ->readpage == NULL it must be shmem_mapping(), 54640814f68SOleg Nesterov * see uprobe_register(). 547a5f4374aSIngo Molnar */ 54840814f68SOleg Nesterov if (mapping->a_ops->readpage) 5492edb7b55SOleg Nesterov page = read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT, filp); 55040814f68SOleg Nesterov else 55140814f68SOleg Nesterov page = shmem_read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT); 552a5f4374aSIngo Molnar if (IS_ERR(page)) 553a5f4374aSIngo Molnar return PTR_ERR(page); 554a5f4374aSIngo Molnar 5552edb7b55SOleg Nesterov copy_from_page(page, offset, insn, nbytes); 556a5f4374aSIngo Molnar page_cache_release(page); 557a5f4374aSIngo Molnar 558a5f4374aSIngo Molnar return 0; 559a5f4374aSIngo Molnar } 560a5f4374aSIngo Molnar 561d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 562a5f4374aSIngo Molnar { 5632ded0980SOleg Nesterov struct address_space *mapping = uprobe->inode->i_mapping; 5642ded0980SOleg Nesterov loff_t offs = uprobe->offset; 565803200e2SOleg Nesterov void *insn = &uprobe->arch.insn; 566803200e2SOleg Nesterov int size = sizeof(uprobe->arch.insn); 5672ded0980SOleg Nesterov int len, err = -EIO; 568a5f4374aSIngo Molnar 5692ded0980SOleg Nesterov /* Copy only available bytes, -EIO if nothing was read */ 5702ded0980SOleg Nesterov do { 5712ded0980SOleg Nesterov if (offs >= i_size_read(uprobe->inode)) 5722ded0980SOleg Nesterov break; 573a5f4374aSIngo Molnar 5742ded0980SOleg Nesterov len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); 5752ded0980SOleg Nesterov err = __copy_insn(mapping, filp, insn, len, offs); 576fc36f595SOleg Nesterov if (err) 5772ded0980SOleg Nesterov break; 5782ded0980SOleg Nesterov 5792ded0980SOleg Nesterov insn += len; 5802ded0980SOleg Nesterov offs += len; 5812ded0980SOleg Nesterov size -= len; 5822ded0980SOleg Nesterov } while (size); 5832ded0980SOleg Nesterov 584fc36f595SOleg Nesterov return err; 585a5f4374aSIngo Molnar } 586a5f4374aSIngo Molnar 587cb9a19feSOleg Nesterov static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 588cb9a19feSOleg Nesterov struct mm_struct *mm, unsigned long vaddr) 589cb9a19feSOleg Nesterov { 590cb9a19feSOleg Nesterov int ret = 0; 591cb9a19feSOleg Nesterov 59271434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 593cb9a19feSOleg Nesterov return ret; 594cb9a19feSOleg Nesterov 595d4d3ccc6SOleg Nesterov /* TODO: move this into _register, until then we abuse this sem. */ 596d4d3ccc6SOleg Nesterov down_write(&uprobe->consumer_rwsem); 59771434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 5984710f05fSOleg Nesterov goto out; 5994710f05fSOleg Nesterov 600cb9a19feSOleg Nesterov ret = copy_insn(uprobe, file); 601cb9a19feSOleg Nesterov if (ret) 602cb9a19feSOleg Nesterov goto out; 603cb9a19feSOleg Nesterov 604cb9a19feSOleg Nesterov ret = -ENOTSUPP; 605803200e2SOleg Nesterov if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) 606cb9a19feSOleg Nesterov goto out; 607cb9a19feSOleg Nesterov 608cb9a19feSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 609cb9a19feSOleg Nesterov if (ret) 610cb9a19feSOleg Nesterov goto out; 611cb9a19feSOleg Nesterov 612f72d41faSOleg Nesterov /* uprobe_write_opcode() assumes we don't cross page boundary */ 613cb9a19feSOleg Nesterov BUG_ON((uprobe->offset & ~PAGE_MASK) + 614cb9a19feSOleg Nesterov UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 615cb9a19feSOleg Nesterov 616cb9a19feSOleg Nesterov smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ 61771434f2fSOleg Nesterov set_bit(UPROBE_COPY_INSN, &uprobe->flags); 618cb9a19feSOleg Nesterov 619cb9a19feSOleg Nesterov out: 620d4d3ccc6SOleg Nesterov up_write(&uprobe->consumer_rwsem); 6214710f05fSOleg Nesterov 622cb9a19feSOleg Nesterov return ret; 623cb9a19feSOleg Nesterov } 624cb9a19feSOleg Nesterov 6258a7f2fa0SOleg Nesterov static inline bool consumer_filter(struct uprobe_consumer *uc, 6268a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 627806a98bdSOleg Nesterov { 6288a7f2fa0SOleg Nesterov return !uc->filter || uc->filter(uc, ctx, mm); 629806a98bdSOleg Nesterov } 630806a98bdSOleg Nesterov 6318a7f2fa0SOleg Nesterov static bool filter_chain(struct uprobe *uprobe, 6328a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 63363633cbfSOleg Nesterov { 6341ff6fee5SOleg Nesterov struct uprobe_consumer *uc; 6351ff6fee5SOleg Nesterov bool ret = false; 6361ff6fee5SOleg Nesterov 6371ff6fee5SOleg Nesterov down_read(&uprobe->consumer_rwsem); 6381ff6fee5SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 6398a7f2fa0SOleg Nesterov ret = consumer_filter(uc, ctx, mm); 6401ff6fee5SOleg Nesterov if (ret) 6411ff6fee5SOleg Nesterov break; 6421ff6fee5SOleg Nesterov } 6431ff6fee5SOleg Nesterov up_read(&uprobe->consumer_rwsem); 6441ff6fee5SOleg Nesterov 6451ff6fee5SOleg Nesterov return ret; 64663633cbfSOleg Nesterov } 64763633cbfSOleg Nesterov 648e3343e6aSSrikar Dronamraju static int 649e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 650816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 651a5f4374aSIngo Molnar { 652f8ac4ec9SOleg Nesterov bool first_uprobe; 653a5f4374aSIngo Molnar int ret; 654a5f4374aSIngo Molnar 655cb9a19feSOleg Nesterov ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); 656a5f4374aSIngo Molnar if (ret) 657a5f4374aSIngo Molnar return ret; 658a5f4374aSIngo Molnar 659f8ac4ec9SOleg Nesterov /* 660f8ac4ec9SOleg Nesterov * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), 661f8ac4ec9SOleg Nesterov * the task can hit this breakpoint right after __replace_page(). 662f8ac4ec9SOleg Nesterov */ 663f8ac4ec9SOleg Nesterov first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); 664f8ac4ec9SOleg Nesterov if (first_uprobe) 665f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &mm->flags); 666f8ac4ec9SOleg Nesterov 667816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 6689f68f672SOleg Nesterov if (!ret) 6699f68f672SOleg Nesterov clear_bit(MMF_RECALC_UPROBES, &mm->flags); 6709f68f672SOleg Nesterov else if (first_uprobe) 671f8ac4ec9SOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 672a5f4374aSIngo Molnar 673a5f4374aSIngo Molnar return ret; 674a5f4374aSIngo Molnar } 675a5f4374aSIngo Molnar 676076a365bSOleg Nesterov static int 677816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 678a5f4374aSIngo Molnar { 6799f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &mm->flags); 680076a365bSOleg Nesterov return set_orig_insn(&uprobe->arch, mm, vaddr); 681a5f4374aSIngo Molnar } 682a5f4374aSIngo Molnar 68306b7bcd8SOleg Nesterov static inline bool uprobe_is_active(struct uprobe *uprobe) 68406b7bcd8SOleg Nesterov { 68506b7bcd8SOleg Nesterov return !RB_EMPTY_NODE(&uprobe->rb_node); 68606b7bcd8SOleg Nesterov } 6870326f5a9SSrikar Dronamraju /* 688778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 689778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 690778b032dSOleg Nesterov * See find_active_uprobe(). 6910326f5a9SSrikar Dronamraju */ 692a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 693a5f4374aSIngo Molnar { 69406b7bcd8SOleg Nesterov if (WARN_ON(!uprobe_is_active(uprobe))) 69506b7bcd8SOleg Nesterov return; 69606b7bcd8SOleg Nesterov 6976f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 698a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 6996f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 70006b7bcd8SOleg Nesterov RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ 701a5f4374aSIngo Molnar iput(uprobe->inode); 702a5f4374aSIngo Molnar put_uprobe(uprobe); 703a5f4374aSIngo Molnar } 704a5f4374aSIngo Molnar 70526872090SOleg Nesterov struct map_info { 70626872090SOleg Nesterov struct map_info *next; 70726872090SOleg Nesterov struct mm_struct *mm; 708816c03fbSOleg Nesterov unsigned long vaddr; 70926872090SOleg Nesterov }; 71026872090SOleg Nesterov 71126872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 712a5f4374aSIngo Molnar { 71326872090SOleg Nesterov struct map_info *next = info->next; 71426872090SOleg Nesterov kfree(info); 71526872090SOleg Nesterov return next; 71626872090SOleg Nesterov } 71726872090SOleg Nesterov 71826872090SOleg Nesterov static struct map_info * 71926872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 72026872090SOleg Nesterov { 72126872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 722a5f4374aSIngo Molnar struct vm_area_struct *vma; 72326872090SOleg Nesterov struct map_info *curr = NULL; 72426872090SOleg Nesterov struct map_info *prev = NULL; 72526872090SOleg Nesterov struct map_info *info; 72626872090SOleg Nesterov int more = 0; 727a5f4374aSIngo Molnar 72826872090SOleg Nesterov again: 7294a23717aSDavidlohr Bueso i_mmap_lock_read(mapping); 7306b2dbba8SMichel Lespinasse vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { 731a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 732a5f4374aSIngo Molnar continue; 733a5f4374aSIngo Molnar 7347a5bfb66SOleg Nesterov if (!prev && !more) { 7357a5bfb66SOleg Nesterov /* 736c8c06efaSDavidlohr Bueso * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through 7377a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 7387a5bfb66SOleg Nesterov */ 7397a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 7407a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 7417a5bfb66SOleg Nesterov if (prev) 7427a5bfb66SOleg Nesterov prev->next = NULL; 7437a5bfb66SOleg Nesterov } 74426872090SOleg Nesterov if (!prev) { 74526872090SOleg Nesterov more++; 74626872090SOleg Nesterov continue; 747a5f4374aSIngo Molnar } 748a5f4374aSIngo Molnar 74926872090SOleg Nesterov if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) 75026872090SOleg Nesterov continue; 751a5f4374aSIngo Molnar 75226872090SOleg Nesterov info = prev; 75326872090SOleg Nesterov prev = prev->next; 75426872090SOleg Nesterov info->next = curr; 75526872090SOleg Nesterov curr = info; 75626872090SOleg Nesterov 75726872090SOleg Nesterov info->mm = vma->vm_mm; 75857683f72SOleg Nesterov info->vaddr = offset_to_vaddr(vma, offset); 759a5f4374aSIngo Molnar } 7604a23717aSDavidlohr Bueso i_mmap_unlock_read(mapping); 761a5f4374aSIngo Molnar 76226872090SOleg Nesterov if (!more) 76326872090SOleg Nesterov goto out; 764a5f4374aSIngo Molnar 76526872090SOleg Nesterov prev = curr; 76626872090SOleg Nesterov while (curr) { 76726872090SOleg Nesterov mmput(curr->mm); 76826872090SOleg Nesterov curr = curr->next; 76926872090SOleg Nesterov } 77026872090SOleg Nesterov 77126872090SOleg Nesterov do { 77226872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 77326872090SOleg Nesterov if (!info) { 77426872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 77526872090SOleg Nesterov goto out; 77626872090SOleg Nesterov } 77726872090SOleg Nesterov info->next = prev; 77826872090SOleg Nesterov prev = info; 77926872090SOleg Nesterov } while (--more); 78026872090SOleg Nesterov 78126872090SOleg Nesterov goto again; 78226872090SOleg Nesterov out: 78326872090SOleg Nesterov while (prev) 78426872090SOleg Nesterov prev = free_map_info(prev); 78526872090SOleg Nesterov return curr; 786a5f4374aSIngo Molnar } 787a5f4374aSIngo Molnar 788bdf8647cSOleg Nesterov static int 789bdf8647cSOleg Nesterov register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) 790a5f4374aSIngo Molnar { 791bdf8647cSOleg Nesterov bool is_register = !!new; 79226872090SOleg Nesterov struct map_info *info; 79326872090SOleg Nesterov int err = 0; 79426872090SOleg Nesterov 79532cdba1eSOleg Nesterov percpu_down_write(&dup_mmap_sem); 79626872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 79726872090SOleg Nesterov uprobe->offset, is_register); 79832cdba1eSOleg Nesterov if (IS_ERR(info)) { 79932cdba1eSOleg Nesterov err = PTR_ERR(info); 80032cdba1eSOleg Nesterov goto out; 80132cdba1eSOleg Nesterov } 80226872090SOleg Nesterov 80326872090SOleg Nesterov while (info) { 80426872090SOleg Nesterov struct mm_struct *mm = info->mm; 805a5f4374aSIngo Molnar struct vm_area_struct *vma; 806a5f4374aSIngo Molnar 807076a365bSOleg Nesterov if (err && is_register) 80826872090SOleg Nesterov goto free; 809a5f4374aSIngo Molnar 81077fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 811f4d6dfe5SOleg Nesterov vma = find_vma(mm, info->vaddr); 812f4d6dfe5SOleg Nesterov if (!vma || !valid_vma(vma, is_register) || 813f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 81426872090SOleg Nesterov goto unlock; 81526872090SOleg Nesterov 816f4d6dfe5SOleg Nesterov if (vma->vm_start > info->vaddr || 817f4d6dfe5SOleg Nesterov vaddr_to_offset(vma, info->vaddr) != uprobe->offset) 81826872090SOleg Nesterov goto unlock; 819a5f4374aSIngo Molnar 820806a98bdSOleg Nesterov if (is_register) { 821806a98bdSOleg Nesterov /* consult only the "caller", new consumer. */ 822bdf8647cSOleg Nesterov if (consumer_filter(new, 8238a7f2fa0SOleg Nesterov UPROBE_FILTER_REGISTER, mm)) 82426872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 825806a98bdSOleg Nesterov } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { 8268a7f2fa0SOleg Nesterov if (!filter_chain(uprobe, 8278a7f2fa0SOleg Nesterov UPROBE_FILTER_UNREGISTER, mm)) 828076a365bSOleg Nesterov err |= remove_breakpoint(uprobe, mm, info->vaddr); 829806a98bdSOleg Nesterov } 83078f74116SOleg Nesterov 83126872090SOleg Nesterov unlock: 83226872090SOleg Nesterov up_write(&mm->mmap_sem); 83326872090SOleg Nesterov free: 83426872090SOleg Nesterov mmput(mm); 83526872090SOleg Nesterov info = free_map_info(info); 836a5f4374aSIngo Molnar } 83732cdba1eSOleg Nesterov out: 83832cdba1eSOleg Nesterov percpu_up_write(&dup_mmap_sem); 83926872090SOleg Nesterov return err; 840a5f4374aSIngo Molnar } 841a5f4374aSIngo Molnar 8429a98e03cSOleg Nesterov static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) 843a5f4374aSIngo Molnar { 8449a98e03cSOleg Nesterov consumer_add(uprobe, uc); 845bdf8647cSOleg Nesterov return register_for_each_vma(uprobe, uc); 846a5f4374aSIngo Molnar } 847a5f4374aSIngo Molnar 84804aab9b2SOleg Nesterov static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) 849a5f4374aSIngo Molnar { 85004aab9b2SOleg Nesterov int err; 851a5f4374aSIngo Molnar 85206d07139SOleg Nesterov if (WARN_ON(!consumer_del(uprobe, uc))) 85304aab9b2SOleg Nesterov return; 85404aab9b2SOleg Nesterov 855bdf8647cSOleg Nesterov err = register_for_each_vma(uprobe, NULL); 856a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 857bb929284SOleg Nesterov if (!uprobe->consumers && !err) 85804aab9b2SOleg Nesterov delete_uprobe(uprobe); 85904aab9b2SOleg Nesterov } 860a5f4374aSIngo Molnar 861a5f4374aSIngo Molnar /* 862a5f4374aSIngo Molnar * uprobe_register - register a probe 863a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 864a5f4374aSIngo Molnar * @offset: offset from the start of the file. 865e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 866a5f4374aSIngo Molnar * 867a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 868a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 869a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 870a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 871a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 872e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 873a5f4374aSIngo Molnar * unregisters. 874a5f4374aSIngo Molnar * 875a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 876a5f4374aSIngo Molnar * else return 0 (success) 877a5f4374aSIngo Molnar */ 878e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 879a5f4374aSIngo Molnar { 880a5f4374aSIngo Molnar struct uprobe *uprobe; 881a5f4374aSIngo Molnar int ret; 882a5f4374aSIngo Molnar 883ea024870SAnton Arapov /* Uprobe must have at least one set consumer */ 884ea024870SAnton Arapov if (!uc->handler && !uc->ret_handler) 885ea024870SAnton Arapov return -EINVAL; 886ea024870SAnton Arapov 88740814f68SOleg Nesterov /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ 88840814f68SOleg Nesterov if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) 88941ccba02SOleg Nesterov return -EIO; 890f0744af7SOleg Nesterov /* Racy, just to catch the obvious mistakes */ 891a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 892a5f4374aSIngo Molnar return -EINVAL; 893a5f4374aSIngo Molnar 89466d06dffSOleg Nesterov retry: 895a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 89666d06dffSOleg Nesterov if (!uprobe) 89766d06dffSOleg Nesterov return -ENOMEM; 89866d06dffSOleg Nesterov /* 89966d06dffSOleg Nesterov * We can race with uprobe_unregister()->delete_uprobe(). 90066d06dffSOleg Nesterov * Check uprobe_is_active() and retry if it is false. 90166d06dffSOleg Nesterov */ 902e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 90366d06dffSOleg Nesterov ret = -EAGAIN; 90466d06dffSOleg Nesterov if (likely(uprobe_is_active(uprobe))) { 9059a98e03cSOleg Nesterov ret = __uprobe_register(uprobe, uc); 9069a98e03cSOleg Nesterov if (ret) 90704aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 908a5f4374aSIngo Molnar } 90966d06dffSOleg Nesterov up_write(&uprobe->register_rwsem); 910a5f4374aSIngo Molnar put_uprobe(uprobe); 911a5f4374aSIngo Molnar 91266d06dffSOleg Nesterov if (unlikely(ret == -EAGAIN)) 91366d06dffSOleg Nesterov goto retry; 914a5f4374aSIngo Molnar return ret; 915a5f4374aSIngo Molnar } 916e8440c14SJosh Stone EXPORT_SYMBOL_GPL(uprobe_register); 917a5f4374aSIngo Molnar 918a5f4374aSIngo Molnar /* 919bdf8647cSOleg Nesterov * uprobe_apply - unregister a already registered probe. 920bdf8647cSOleg Nesterov * @inode: the file in which the probe has to be removed. 921bdf8647cSOleg Nesterov * @offset: offset from the start of the file. 922bdf8647cSOleg Nesterov * @uc: consumer which wants to add more or remove some breakpoints 923bdf8647cSOleg Nesterov * @add: add or remove the breakpoints 924bdf8647cSOleg Nesterov */ 925bdf8647cSOleg Nesterov int uprobe_apply(struct inode *inode, loff_t offset, 926bdf8647cSOleg Nesterov struct uprobe_consumer *uc, bool add) 927bdf8647cSOleg Nesterov { 928bdf8647cSOleg Nesterov struct uprobe *uprobe; 929bdf8647cSOleg Nesterov struct uprobe_consumer *con; 930bdf8647cSOleg Nesterov int ret = -ENOENT; 931bdf8647cSOleg Nesterov 932bdf8647cSOleg Nesterov uprobe = find_uprobe(inode, offset); 93306d07139SOleg Nesterov if (WARN_ON(!uprobe)) 934bdf8647cSOleg Nesterov return ret; 935bdf8647cSOleg Nesterov 936bdf8647cSOleg Nesterov down_write(&uprobe->register_rwsem); 937bdf8647cSOleg Nesterov for (con = uprobe->consumers; con && con != uc ; con = con->next) 938bdf8647cSOleg Nesterov ; 939bdf8647cSOleg Nesterov if (con) 940bdf8647cSOleg Nesterov ret = register_for_each_vma(uprobe, add ? uc : NULL); 941bdf8647cSOleg Nesterov up_write(&uprobe->register_rwsem); 942bdf8647cSOleg Nesterov put_uprobe(uprobe); 943bdf8647cSOleg Nesterov 944bdf8647cSOleg Nesterov return ret; 945bdf8647cSOleg Nesterov } 946bdf8647cSOleg Nesterov 947bdf8647cSOleg Nesterov /* 948a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 949a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 950a5f4374aSIngo Molnar * @offset: offset from the start of the file. 951e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 952a5f4374aSIngo Molnar */ 953e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 954a5f4374aSIngo Molnar { 955a5f4374aSIngo Molnar struct uprobe *uprobe; 956a5f4374aSIngo Molnar 957a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 95806d07139SOleg Nesterov if (WARN_ON(!uprobe)) 959a5f4374aSIngo Molnar return; 960a5f4374aSIngo Molnar 961e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 96204aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 963e591c8d7SOleg Nesterov up_write(&uprobe->register_rwsem); 964a5f4374aSIngo Molnar put_uprobe(uprobe); 965a5f4374aSIngo Molnar } 966e8440c14SJosh Stone EXPORT_SYMBOL_GPL(uprobe_unregister); 967a5f4374aSIngo Molnar 968da1816b1SOleg Nesterov static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) 969da1816b1SOleg Nesterov { 970da1816b1SOleg Nesterov struct vm_area_struct *vma; 971da1816b1SOleg Nesterov int err = 0; 972da1816b1SOleg Nesterov 973da1816b1SOleg Nesterov down_read(&mm->mmap_sem); 974da1816b1SOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 975da1816b1SOleg Nesterov unsigned long vaddr; 976da1816b1SOleg Nesterov loff_t offset; 977da1816b1SOleg Nesterov 978da1816b1SOleg Nesterov if (!valid_vma(vma, false) || 979f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 980da1816b1SOleg Nesterov continue; 981da1816b1SOleg Nesterov 982da1816b1SOleg Nesterov offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; 983da1816b1SOleg Nesterov if (uprobe->offset < offset || 984da1816b1SOleg Nesterov uprobe->offset >= offset + vma->vm_end - vma->vm_start) 985da1816b1SOleg Nesterov continue; 986da1816b1SOleg Nesterov 987da1816b1SOleg Nesterov vaddr = offset_to_vaddr(vma, uprobe->offset); 988da1816b1SOleg Nesterov err |= remove_breakpoint(uprobe, mm, vaddr); 989da1816b1SOleg Nesterov } 990da1816b1SOleg Nesterov up_read(&mm->mmap_sem); 991da1816b1SOleg Nesterov 992da1816b1SOleg Nesterov return err; 993da1816b1SOleg Nesterov } 994da1816b1SOleg Nesterov 995891c3970SOleg Nesterov static struct rb_node * 996891c3970SOleg Nesterov find_node_in_range(struct inode *inode, loff_t min, loff_t max) 997a5f4374aSIngo Molnar { 998a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 999a5f4374aSIngo Molnar 1000a5f4374aSIngo Molnar while (n) { 1001891c3970SOleg Nesterov struct uprobe *u = rb_entry(n, struct uprobe, rb_node); 1002a5f4374aSIngo Molnar 1003891c3970SOleg Nesterov if (inode < u->inode) { 1004a5f4374aSIngo Molnar n = n->rb_left; 1005891c3970SOleg Nesterov } else if (inode > u->inode) { 1006a5f4374aSIngo Molnar n = n->rb_right; 1007891c3970SOleg Nesterov } else { 1008891c3970SOleg Nesterov if (max < u->offset) 1009891c3970SOleg Nesterov n = n->rb_left; 1010891c3970SOleg Nesterov else if (min > u->offset) 1011891c3970SOleg Nesterov n = n->rb_right; 1012891c3970SOleg Nesterov else 1013891c3970SOleg Nesterov break; 1014891c3970SOleg Nesterov } 1015a5f4374aSIngo Molnar } 1016a5f4374aSIngo Molnar 1017891c3970SOleg Nesterov return n; 1018a5f4374aSIngo Molnar } 1019a5f4374aSIngo Molnar 1020a5f4374aSIngo Molnar /* 1021891c3970SOleg Nesterov * For a given range in vma, build a list of probes that need to be inserted. 1022a5f4374aSIngo Molnar */ 1023891c3970SOleg Nesterov static void build_probe_list(struct inode *inode, 1024891c3970SOleg Nesterov struct vm_area_struct *vma, 1025891c3970SOleg Nesterov unsigned long start, unsigned long end, 1026891c3970SOleg Nesterov struct list_head *head) 1027a5f4374aSIngo Molnar { 1028891c3970SOleg Nesterov loff_t min, max; 1029891c3970SOleg Nesterov struct rb_node *n, *t; 1030891c3970SOleg Nesterov struct uprobe *u; 1031891c3970SOleg Nesterov 1032891c3970SOleg Nesterov INIT_LIST_HEAD(head); 1033cb113b47SOleg Nesterov min = vaddr_to_offset(vma, start); 1034891c3970SOleg Nesterov max = min + (end - start) - 1; 1035a5f4374aSIngo Molnar 10366f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 1037891c3970SOleg Nesterov n = find_node_in_range(inode, min, max); 1038891c3970SOleg Nesterov if (n) { 1039891c3970SOleg Nesterov for (t = n; t; t = rb_prev(t)) { 1040891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1041891c3970SOleg Nesterov if (u->inode != inode || u->offset < min) 1042a5f4374aSIngo Molnar break; 1043891c3970SOleg Nesterov list_add(&u->pending_list, head); 1044f231722aSOleg Nesterov get_uprobe(u); 1045a5f4374aSIngo Molnar } 1046891c3970SOleg Nesterov for (t = n; (t = rb_next(t)); ) { 1047891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1048891c3970SOleg Nesterov if (u->inode != inode || u->offset > max) 1049891c3970SOleg Nesterov break; 1050891c3970SOleg Nesterov list_add(&u->pending_list, head); 1051f231722aSOleg Nesterov get_uprobe(u); 1052891c3970SOleg Nesterov } 1053891c3970SOleg Nesterov } 10546f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 1055a5f4374aSIngo Molnar } 1056a5f4374aSIngo Molnar 1057a5f4374aSIngo Molnar /* 10585e5be71aSOleg Nesterov * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. 1059a5f4374aSIngo Molnar * 10605e5be71aSOleg Nesterov * Currently we ignore all errors and always return 0, the callers 10615e5be71aSOleg Nesterov * can't handle the failure anyway. 1062a5f4374aSIngo Molnar */ 1063a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1064a5f4374aSIngo Molnar { 1065a5f4374aSIngo Molnar struct list_head tmp_list; 1066665605a2SOleg Nesterov struct uprobe *uprobe, *u; 1067a5f4374aSIngo Molnar struct inode *inode; 1068a5f4374aSIngo Molnar 1069441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, true)) 1070a5f4374aSIngo Molnar return 0; 1071a5f4374aSIngo Molnar 1072f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 1073a5f4374aSIngo Molnar if (!inode) 1074a5f4374aSIngo Molnar return 0; 1075a5f4374aSIngo Molnar 1076a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1077891c3970SOleg Nesterov build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); 1078806a98bdSOleg Nesterov /* 1079806a98bdSOleg Nesterov * We can race with uprobe_unregister(), this uprobe can be already 1080806a98bdSOleg Nesterov * removed. But in this case filter_chain() must return false, all 1081806a98bdSOleg Nesterov * consumers have gone away. 1082806a98bdSOleg Nesterov */ 1083665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 1084806a98bdSOleg Nesterov if (!fatal_signal_pending(current) && 10858a7f2fa0SOleg Nesterov filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { 108657683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 10875e5be71aSOleg Nesterov install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1088a5f4374aSIngo Molnar } 1089a5f4374aSIngo Molnar put_uprobe(uprobe); 1090a5f4374aSIngo Molnar } 1091a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1092a5f4374aSIngo Molnar 10935e5be71aSOleg Nesterov return 0; 1094a5f4374aSIngo Molnar } 1095a5f4374aSIngo Molnar 10969f68f672SOleg Nesterov static bool 10979f68f672SOleg Nesterov vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) 10989f68f672SOleg Nesterov { 10999f68f672SOleg Nesterov loff_t min, max; 11009f68f672SOleg Nesterov struct inode *inode; 11019f68f672SOleg Nesterov struct rb_node *n; 11029f68f672SOleg Nesterov 1103f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 11049f68f672SOleg Nesterov 11059f68f672SOleg Nesterov min = vaddr_to_offset(vma, start); 11069f68f672SOleg Nesterov max = min + (end - start) - 1; 11079f68f672SOleg Nesterov 11089f68f672SOleg Nesterov spin_lock(&uprobes_treelock); 11099f68f672SOleg Nesterov n = find_node_in_range(inode, min, max); 11109f68f672SOleg Nesterov spin_unlock(&uprobes_treelock); 11119f68f672SOleg Nesterov 11129f68f672SOleg Nesterov return !!n; 11139f68f672SOleg Nesterov } 11149f68f672SOleg Nesterov 1115682968e0SSrikar Dronamraju /* 1116682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1117682968e0SSrikar Dronamraju */ 1118cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1119682968e0SSrikar Dronamraju { 1120441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, false)) 1121682968e0SSrikar Dronamraju return; 1122682968e0SSrikar Dronamraju 11232fd611a9SOleg Nesterov if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ 11242fd611a9SOleg Nesterov return; 11252fd611a9SOleg Nesterov 11269f68f672SOleg Nesterov if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || 11279f68f672SOleg Nesterov test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) 1128f8ac4ec9SOleg Nesterov return; 1129f8ac4ec9SOleg Nesterov 11309f68f672SOleg Nesterov if (vma_has_uprobes(vma, start, end)) 11319f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); 1132682968e0SSrikar Dronamraju } 1133682968e0SSrikar Dronamraju 1134d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 11356441ec8bSOleg Nesterov static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) 1136d4b3b638SSrikar Dronamraju { 1137c8a82538SOleg Nesterov int ret = -EALREADY; 1138d4b3b638SSrikar Dronamraju 1139d4b3b638SSrikar Dronamraju down_write(&mm->mmap_sem); 1140d4b3b638SSrikar Dronamraju if (mm->uprobes_state.xol_area) 1141d4b3b638SSrikar Dronamraju goto fail; 1142d4b3b638SSrikar Dronamraju 1143af0d95afSOleg Nesterov if (!area->vaddr) { 1144d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1145af0d95afSOleg Nesterov area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, 1146af0d95afSOleg Nesterov PAGE_SIZE, 0, 0); 1147d4b3b638SSrikar Dronamraju if (area->vaddr & ~PAGE_MASK) { 1148d4b3b638SSrikar Dronamraju ret = area->vaddr; 1149d4b3b638SSrikar Dronamraju goto fail; 1150d4b3b638SSrikar Dronamraju } 1151af0d95afSOleg Nesterov } 1152d4b3b638SSrikar Dronamraju 1153d4b3b638SSrikar Dronamraju ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1154d4b3b638SSrikar Dronamraju VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); 1155d4b3b638SSrikar Dronamraju if (ret) 1156d4b3b638SSrikar Dronamraju goto fail; 1157d4b3b638SSrikar Dronamraju 1158d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1159d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1160d4b3b638SSrikar Dronamraju fail: 1161d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1162d4b3b638SSrikar Dronamraju 1163d4b3b638SSrikar Dronamraju return ret; 1164d4b3b638SSrikar Dronamraju } 1165d4b3b638SSrikar Dronamraju 1166af0d95afSOleg Nesterov static struct xol_area *__create_xol_area(unsigned long vaddr) 1167d4b3b638SSrikar Dronamraju { 11689b545df8SOleg Nesterov struct mm_struct *mm = current->mm; 1169e78aebfdSAnton Arapov uprobe_opcode_t insn = UPROBE_SWBP_INSN; 11706441ec8bSOleg Nesterov struct xol_area *area; 11719b545df8SOleg Nesterov 1172af0d95afSOleg Nesterov area = kmalloc(sizeof(*area), GFP_KERNEL); 1173d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1174c8a82538SOleg Nesterov goto out; 1175d4b3b638SSrikar Dronamraju 1176d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1177d4b3b638SSrikar Dronamraju if (!area->bitmap) 1178c8a82538SOleg Nesterov goto free_area; 1179c8a82538SOleg Nesterov 1180c8a82538SOleg Nesterov area->page = alloc_page(GFP_HIGHUSER); 1181c8a82538SOleg Nesterov if (!area->page) 1182c8a82538SOleg Nesterov goto free_bitmap; 1183d4b3b638SSrikar Dronamraju 1184af0d95afSOleg Nesterov area->vaddr = vaddr; 1185d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 11866441ec8bSOleg Nesterov /* Reserve the 1st slot for get_trampoline_vaddr() */ 11876441ec8bSOleg Nesterov set_bit(0, area->bitmap); 11886441ec8bSOleg Nesterov atomic_set(&area->slot_count, 1); 11896441ec8bSOleg Nesterov copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE); 1190e78aebfdSAnton Arapov 11916441ec8bSOleg Nesterov if (!xol_add_vma(mm, area)) 1192d4b3b638SSrikar Dronamraju return area; 1193d4b3b638SSrikar Dronamraju 1194c8a82538SOleg Nesterov __free_page(area->page); 1195c8a82538SOleg Nesterov free_bitmap: 1196d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1197c8a82538SOleg Nesterov free_area: 1198d4b3b638SSrikar Dronamraju kfree(area); 1199c8a82538SOleg Nesterov out: 12006441ec8bSOleg Nesterov return NULL; 12016441ec8bSOleg Nesterov } 12026441ec8bSOleg Nesterov 12036441ec8bSOleg Nesterov /* 12046441ec8bSOleg Nesterov * get_xol_area - Allocate process's xol_area if necessary. 12056441ec8bSOleg Nesterov * This area will be used for storing instructions for execution out of line. 12066441ec8bSOleg Nesterov * 12076441ec8bSOleg Nesterov * Returns the allocated area or NULL. 12086441ec8bSOleg Nesterov */ 12096441ec8bSOleg Nesterov static struct xol_area *get_xol_area(void) 12106441ec8bSOleg Nesterov { 12116441ec8bSOleg Nesterov struct mm_struct *mm = current->mm; 12126441ec8bSOleg Nesterov struct xol_area *area; 12136441ec8bSOleg Nesterov 12146441ec8bSOleg Nesterov if (!mm->uprobes_state.xol_area) 1215af0d95afSOleg Nesterov __create_xol_area(0); 12166441ec8bSOleg Nesterov 12179b545df8SOleg Nesterov area = mm->uprobes_state.xol_area; 12189b545df8SOleg Nesterov smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 12199b545df8SOleg Nesterov return area; 1220d4b3b638SSrikar Dronamraju } 1221d4b3b638SSrikar Dronamraju 1222d4b3b638SSrikar Dronamraju /* 1223d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1224d4b3b638SSrikar Dronamraju */ 1225d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1226d4b3b638SSrikar Dronamraju { 1227d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1228d4b3b638SSrikar Dronamraju 1229d4b3b638SSrikar Dronamraju if (!area) 1230d4b3b638SSrikar Dronamraju return; 1231d4b3b638SSrikar Dronamraju 1232d4b3b638SSrikar Dronamraju put_page(area->page); 1233d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1234d4b3b638SSrikar Dronamraju kfree(area); 1235d4b3b638SSrikar Dronamraju } 1236d4b3b638SSrikar Dronamraju 123732cdba1eSOleg Nesterov void uprobe_start_dup_mmap(void) 123832cdba1eSOleg Nesterov { 123932cdba1eSOleg Nesterov percpu_down_read(&dup_mmap_sem); 124032cdba1eSOleg Nesterov } 124132cdba1eSOleg Nesterov 124232cdba1eSOleg Nesterov void uprobe_end_dup_mmap(void) 124332cdba1eSOleg Nesterov { 124432cdba1eSOleg Nesterov percpu_up_read(&dup_mmap_sem); 124532cdba1eSOleg Nesterov } 124632cdba1eSOleg Nesterov 1247f8ac4ec9SOleg Nesterov void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) 1248f8ac4ec9SOleg Nesterov { 124961559a81SOleg Nesterov newmm->uprobes_state.xol_area = NULL; 125061559a81SOleg Nesterov 12519f68f672SOleg Nesterov if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { 1252f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &newmm->flags); 12539f68f672SOleg Nesterov /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ 12549f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &newmm->flags); 12559f68f672SOleg Nesterov } 1256f8ac4ec9SOleg Nesterov } 1257f8ac4ec9SOleg Nesterov 1258d4b3b638SSrikar Dronamraju /* 1259d4b3b638SSrikar Dronamraju * - search for a free slot. 1260d4b3b638SSrikar Dronamraju */ 1261d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1262d4b3b638SSrikar Dronamraju { 1263d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1264d4b3b638SSrikar Dronamraju int slot_nr; 1265d4b3b638SSrikar Dronamraju 1266d4b3b638SSrikar Dronamraju do { 1267d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1268d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1269d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1270d4b3b638SSrikar Dronamraju break; 1271d4b3b638SSrikar Dronamraju 1272d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1273d4b3b638SSrikar Dronamraju continue; 1274d4b3b638SSrikar Dronamraju } 1275d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1276d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1277d4b3b638SSrikar Dronamraju 1278d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1279d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1280d4b3b638SSrikar Dronamraju 1281d4b3b638SSrikar Dronamraju return slot_addr; 1282d4b3b638SSrikar Dronamraju } 1283d4b3b638SSrikar Dronamraju 1284d4b3b638SSrikar Dronamraju /* 1285a6cb3f6dSOleg Nesterov * xol_get_insn_slot - allocate a slot for xol. 1286d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1287d4b3b638SSrikar Dronamraju */ 1288a6cb3f6dSOleg Nesterov static unsigned long xol_get_insn_slot(struct uprobe *uprobe) 1289d4b3b638SSrikar Dronamraju { 1290d4b3b638SSrikar Dronamraju struct xol_area *area; 1291a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1292d4b3b638SSrikar Dronamraju 12939b545df8SOleg Nesterov area = get_xol_area(); 1294d4b3b638SSrikar Dronamraju if (!area) 1295d4b3b638SSrikar Dronamraju return 0; 1296d4b3b638SSrikar Dronamraju 1297a6cb3f6dSOleg Nesterov xol_vaddr = xol_take_insn_slot(area); 1298a6cb3f6dSOleg Nesterov if (unlikely(!xol_vaddr)) 1299d4b3b638SSrikar Dronamraju return 0; 1300d4b3b638SSrikar Dronamraju 130172e6ae28SVictor Kamensky arch_uprobe_copy_ixol(area->page, xol_vaddr, 1302803200e2SOleg Nesterov &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); 1303d4b3b638SSrikar Dronamraju 1304a6cb3f6dSOleg Nesterov return xol_vaddr; 1305d4b3b638SSrikar Dronamraju } 1306d4b3b638SSrikar Dronamraju 1307d4b3b638SSrikar Dronamraju /* 1308d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1309d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1310d4b3b638SSrikar Dronamraju * subsequent requests. 1311d4b3b638SSrikar Dronamraju */ 1312d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1313d4b3b638SSrikar Dronamraju { 1314d4b3b638SSrikar Dronamraju struct xol_area *area; 1315d4b3b638SSrikar Dronamraju unsigned long vma_end; 1316d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1317d4b3b638SSrikar Dronamraju 1318d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1319d4b3b638SSrikar Dronamraju return; 1320d4b3b638SSrikar Dronamraju 1321d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1322af4355e9SOleg Nesterov if (unlikely(!slot_addr)) 1323d4b3b638SSrikar Dronamraju return; 1324d4b3b638SSrikar Dronamraju 1325d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1326d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1327d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1328d4b3b638SSrikar Dronamraju unsigned long offset; 1329d4b3b638SSrikar Dronamraju int slot_nr; 1330d4b3b638SSrikar Dronamraju 1331d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1332d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1333d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1334d4b3b638SSrikar Dronamraju return; 1335d4b3b638SSrikar Dronamraju 1336d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1337d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 1338d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1339d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1340d4b3b638SSrikar Dronamraju 1341d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1342d4b3b638SSrikar Dronamraju } 1343d4b3b638SSrikar Dronamraju } 1344d4b3b638SSrikar Dronamraju 134572e6ae28SVictor Kamensky void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, 134672e6ae28SVictor Kamensky void *src, unsigned long len) 134772e6ae28SVictor Kamensky { 134872e6ae28SVictor Kamensky /* Initialize the slot */ 134972e6ae28SVictor Kamensky copy_to_page(page, vaddr, src, len); 135072e6ae28SVictor Kamensky 135172e6ae28SVictor Kamensky /* 135272e6ae28SVictor Kamensky * We probably need flush_icache_user_range() but it needs vma. 135372e6ae28SVictor Kamensky * This should work on most of architectures by default. If 135472e6ae28SVictor Kamensky * architecture needs to do something different it can define 135572e6ae28SVictor Kamensky * its own version of the function. 135672e6ae28SVictor Kamensky */ 135772e6ae28SVictor Kamensky flush_dcache_page(page); 135872e6ae28SVictor Kamensky } 135972e6ae28SVictor Kamensky 13600326f5a9SSrikar Dronamraju /** 13610326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 13620326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 13630326f5a9SSrikar Dronamraju * instruction. 13640326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 13650326f5a9SSrikar Dronamraju */ 13660326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 13670326f5a9SSrikar Dronamraju { 13680326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 13690326f5a9SSrikar Dronamraju } 13700326f5a9SSrikar Dronamraju 1371b02ef20aSOleg Nesterov unsigned long uprobe_get_trap_addr(struct pt_regs *regs) 1372b02ef20aSOleg Nesterov { 1373b02ef20aSOleg Nesterov struct uprobe_task *utask = current->utask; 1374b02ef20aSOleg Nesterov 1375b02ef20aSOleg Nesterov if (unlikely(utask && utask->active_uprobe)) 1376b02ef20aSOleg Nesterov return utask->vaddr; 1377b02ef20aSOleg Nesterov 1378b02ef20aSOleg Nesterov return instruction_pointer(regs); 1379b02ef20aSOleg Nesterov } 1380b02ef20aSOleg Nesterov 13812bb5e840SOleg Nesterov static struct return_instance *free_ret_instance(struct return_instance *ri) 13822bb5e840SOleg Nesterov { 13832bb5e840SOleg Nesterov struct return_instance *next = ri->next; 13842bb5e840SOleg Nesterov put_uprobe(ri->uprobe); 13852bb5e840SOleg Nesterov kfree(ri); 13862bb5e840SOleg Nesterov return next; 13872bb5e840SOleg Nesterov } 13882bb5e840SOleg Nesterov 13890326f5a9SSrikar Dronamraju /* 13900326f5a9SSrikar Dronamraju * Called with no locks held. 13910326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 13920326f5a9SSrikar Dronamraju */ 13930326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 13940326f5a9SSrikar Dronamraju { 13950326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13962bb5e840SOleg Nesterov struct return_instance *ri; 13970326f5a9SSrikar Dronamraju 13980326f5a9SSrikar Dronamraju if (!utask) 13990326f5a9SSrikar Dronamraju return; 14000326f5a9SSrikar Dronamraju 14010326f5a9SSrikar Dronamraju if (utask->active_uprobe) 14020326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 14030326f5a9SSrikar Dronamraju 14040dfd0eb8SAnton Arapov ri = utask->return_instances; 14052bb5e840SOleg Nesterov while (ri) 14062bb5e840SOleg Nesterov ri = free_ret_instance(ri); 14070dfd0eb8SAnton Arapov 1408d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 14090326f5a9SSrikar Dronamraju kfree(utask); 14100326f5a9SSrikar Dronamraju t->utask = NULL; 14110326f5a9SSrikar Dronamraju } 14120326f5a9SSrikar Dronamraju 14130326f5a9SSrikar Dronamraju /* 14145a2df662SOleg Nesterov * Allocate a uprobe_task object for the task if if necessary. 14155a2df662SOleg Nesterov * Called when the thread hits a breakpoint. 14160326f5a9SSrikar Dronamraju * 14170326f5a9SSrikar Dronamraju * Returns: 14180326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 14190326f5a9SSrikar Dronamraju * - NULL otherwise 14200326f5a9SSrikar Dronamraju */ 14215a2df662SOleg Nesterov static struct uprobe_task *get_utask(void) 14220326f5a9SSrikar Dronamraju { 14235a2df662SOleg Nesterov if (!current->utask) 14245a2df662SOleg Nesterov current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 14255a2df662SOleg Nesterov return current->utask; 14260326f5a9SSrikar Dronamraju } 14270326f5a9SSrikar Dronamraju 1428248d3a7bSOleg Nesterov static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) 1429248d3a7bSOleg Nesterov { 1430248d3a7bSOleg Nesterov struct uprobe_task *n_utask; 1431248d3a7bSOleg Nesterov struct return_instance **p, *o, *n; 1432248d3a7bSOleg Nesterov 1433248d3a7bSOleg Nesterov n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 1434248d3a7bSOleg Nesterov if (!n_utask) 1435248d3a7bSOleg Nesterov return -ENOMEM; 1436248d3a7bSOleg Nesterov t->utask = n_utask; 1437248d3a7bSOleg Nesterov 1438248d3a7bSOleg Nesterov p = &n_utask->return_instances; 1439248d3a7bSOleg Nesterov for (o = o_utask->return_instances; o; o = o->next) { 1440248d3a7bSOleg Nesterov n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); 1441248d3a7bSOleg Nesterov if (!n) 1442248d3a7bSOleg Nesterov return -ENOMEM; 1443248d3a7bSOleg Nesterov 1444248d3a7bSOleg Nesterov *n = *o; 1445f231722aSOleg Nesterov get_uprobe(n->uprobe); 1446248d3a7bSOleg Nesterov n->next = NULL; 1447248d3a7bSOleg Nesterov 1448248d3a7bSOleg Nesterov *p = n; 1449248d3a7bSOleg Nesterov p = &n->next; 1450248d3a7bSOleg Nesterov n_utask->depth++; 1451248d3a7bSOleg Nesterov } 1452248d3a7bSOleg Nesterov 1453248d3a7bSOleg Nesterov return 0; 1454248d3a7bSOleg Nesterov } 1455248d3a7bSOleg Nesterov 1456248d3a7bSOleg Nesterov static void uprobe_warn(struct task_struct *t, const char *msg) 1457248d3a7bSOleg Nesterov { 1458248d3a7bSOleg Nesterov pr_warn("uprobe: %s:%d failed to %s\n", 1459248d3a7bSOleg Nesterov current->comm, current->pid, msg); 1460248d3a7bSOleg Nesterov } 1461248d3a7bSOleg Nesterov 1462aa59c53fSOleg Nesterov static void dup_xol_work(struct callback_head *work) 1463aa59c53fSOleg Nesterov { 1464aa59c53fSOleg Nesterov if (current->flags & PF_EXITING) 1465aa59c53fSOleg Nesterov return; 1466aa59c53fSOleg Nesterov 146732473431SOleg Nesterov if (!__create_xol_area(current->utask->dup_xol_addr)) 1468aa59c53fSOleg Nesterov uprobe_warn(current, "dup xol area"); 1469aa59c53fSOleg Nesterov } 1470aa59c53fSOleg Nesterov 1471e78aebfdSAnton Arapov /* 1472b68e0749SOleg Nesterov * Called in context of a new clone/fork from copy_process. 1473b68e0749SOleg Nesterov */ 14743ab67966SOleg Nesterov void uprobe_copy_process(struct task_struct *t, unsigned long flags) 1475b68e0749SOleg Nesterov { 1476248d3a7bSOleg Nesterov struct uprobe_task *utask = current->utask; 1477248d3a7bSOleg Nesterov struct mm_struct *mm = current->mm; 1478aa59c53fSOleg Nesterov struct xol_area *area; 1479248d3a7bSOleg Nesterov 1480b68e0749SOleg Nesterov t->utask = NULL; 1481248d3a7bSOleg Nesterov 14823ab67966SOleg Nesterov if (!utask || !utask->return_instances) 14833ab67966SOleg Nesterov return; 14843ab67966SOleg Nesterov 14853ab67966SOleg Nesterov if (mm == t->mm && !(flags & CLONE_VFORK)) 1486248d3a7bSOleg Nesterov return; 1487248d3a7bSOleg Nesterov 1488248d3a7bSOleg Nesterov if (dup_utask(t, utask)) 1489248d3a7bSOleg Nesterov return uprobe_warn(t, "dup ret instances"); 1490aa59c53fSOleg Nesterov 1491aa59c53fSOleg Nesterov /* The task can fork() after dup_xol_work() fails */ 1492aa59c53fSOleg Nesterov area = mm->uprobes_state.xol_area; 1493aa59c53fSOleg Nesterov if (!area) 1494aa59c53fSOleg Nesterov return uprobe_warn(t, "dup xol area"); 1495aa59c53fSOleg Nesterov 14963ab67966SOleg Nesterov if (mm == t->mm) 14973ab67966SOleg Nesterov return; 14983ab67966SOleg Nesterov 149932473431SOleg Nesterov t->utask->dup_xol_addr = area->vaddr; 150032473431SOleg Nesterov init_task_work(&t->utask->dup_xol_work, dup_xol_work); 150132473431SOleg Nesterov task_work_add(t, &t->utask->dup_xol_work, true); 1502b68e0749SOleg Nesterov } 1503b68e0749SOleg Nesterov 1504b68e0749SOleg Nesterov /* 1505e78aebfdSAnton Arapov * Current area->vaddr notion assume the trampoline address is always 1506e78aebfdSAnton Arapov * equal area->vaddr. 1507e78aebfdSAnton Arapov * 1508e78aebfdSAnton Arapov * Returns -1 in case the xol_area is not allocated. 1509e78aebfdSAnton Arapov */ 1510e78aebfdSAnton Arapov static unsigned long get_trampoline_vaddr(void) 1511e78aebfdSAnton Arapov { 1512e78aebfdSAnton Arapov struct xol_area *area; 1513e78aebfdSAnton Arapov unsigned long trampoline_vaddr = -1; 1514e78aebfdSAnton Arapov 1515e78aebfdSAnton Arapov area = current->mm->uprobes_state.xol_area; 1516e78aebfdSAnton Arapov smp_read_barrier_depends(); 1517e78aebfdSAnton Arapov if (area) 1518e78aebfdSAnton Arapov trampoline_vaddr = area->vaddr; 1519e78aebfdSAnton Arapov 1520e78aebfdSAnton Arapov return trampoline_vaddr; 1521e78aebfdSAnton Arapov } 1522e78aebfdSAnton Arapov 15230dfd0eb8SAnton Arapov static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) 15240dfd0eb8SAnton Arapov { 15250dfd0eb8SAnton Arapov struct return_instance *ri; 15260dfd0eb8SAnton Arapov struct uprobe_task *utask; 15270dfd0eb8SAnton Arapov unsigned long orig_ret_vaddr, trampoline_vaddr; 15280dfd0eb8SAnton Arapov bool chained = false; 15290dfd0eb8SAnton Arapov 15300dfd0eb8SAnton Arapov if (!get_xol_area()) 15310dfd0eb8SAnton Arapov return; 15320dfd0eb8SAnton Arapov 15330dfd0eb8SAnton Arapov utask = get_utask(); 15340dfd0eb8SAnton Arapov if (!utask) 15350dfd0eb8SAnton Arapov return; 15360dfd0eb8SAnton Arapov 1537ded49c55SAnton Arapov if (utask->depth >= MAX_URETPROBE_DEPTH) { 1538ded49c55SAnton Arapov printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" 1539ded49c55SAnton Arapov " nestedness limit pid/tgid=%d/%d\n", 1540ded49c55SAnton Arapov current->pid, current->tgid); 1541ded49c55SAnton Arapov return; 1542ded49c55SAnton Arapov } 1543ded49c55SAnton Arapov 15446c58d0e4SOleg Nesterov ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); 15450dfd0eb8SAnton Arapov if (!ri) 15466c58d0e4SOleg Nesterov return; 15470dfd0eb8SAnton Arapov 15480dfd0eb8SAnton Arapov trampoline_vaddr = get_trampoline_vaddr(); 15490dfd0eb8SAnton Arapov orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); 15500dfd0eb8SAnton Arapov if (orig_ret_vaddr == -1) 15510dfd0eb8SAnton Arapov goto fail; 15520dfd0eb8SAnton Arapov 15530dfd0eb8SAnton Arapov /* 15540dfd0eb8SAnton Arapov * We don't want to keep trampoline address in stack, rather keep the 15550dfd0eb8SAnton Arapov * original return address of first caller thru all the consequent 15560dfd0eb8SAnton Arapov * instances. This also makes breakpoint unwrapping easier. 15570dfd0eb8SAnton Arapov */ 15580dfd0eb8SAnton Arapov if (orig_ret_vaddr == trampoline_vaddr) { 15590dfd0eb8SAnton Arapov if (!utask->return_instances) { 15600dfd0eb8SAnton Arapov /* 15610dfd0eb8SAnton Arapov * This situation is not possible. Likely we have an 15620dfd0eb8SAnton Arapov * attack from user-space. 15630dfd0eb8SAnton Arapov */ 15646c58d0e4SOleg Nesterov uprobe_warn(current, "handle tail call"); 15650dfd0eb8SAnton Arapov goto fail; 15660dfd0eb8SAnton Arapov } 15670dfd0eb8SAnton Arapov 15680dfd0eb8SAnton Arapov chained = true; 15690dfd0eb8SAnton Arapov orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; 15700dfd0eb8SAnton Arapov } 15710dfd0eb8SAnton Arapov 1572f231722aSOleg Nesterov ri->uprobe = get_uprobe(uprobe); 15730dfd0eb8SAnton Arapov ri->func = instruction_pointer(regs); 15740dfd0eb8SAnton Arapov ri->orig_ret_vaddr = orig_ret_vaddr; 15750dfd0eb8SAnton Arapov ri->chained = chained; 15760dfd0eb8SAnton Arapov 1577ded49c55SAnton Arapov utask->depth++; 15780dfd0eb8SAnton Arapov ri->next = utask->return_instances; 15790dfd0eb8SAnton Arapov utask->return_instances = ri; 15800dfd0eb8SAnton Arapov 15810dfd0eb8SAnton Arapov return; 15820dfd0eb8SAnton Arapov fail: 15830dfd0eb8SAnton Arapov kfree(ri); 15840dfd0eb8SAnton Arapov } 15850dfd0eb8SAnton Arapov 15860326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 15870326f5a9SSrikar Dronamraju static int 1588a6cb3f6dSOleg Nesterov pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) 15890326f5a9SSrikar Dronamraju { 1590a6cb3f6dSOleg Nesterov struct uprobe_task *utask; 1591a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1592aba51024SOleg Nesterov int err; 1593d4b3b638SSrikar Dronamraju 1594608e7427SOleg Nesterov utask = get_utask(); 1595608e7427SOleg Nesterov if (!utask) 1596608e7427SOleg Nesterov return -ENOMEM; 1597a6cb3f6dSOleg Nesterov 1598a6cb3f6dSOleg Nesterov xol_vaddr = xol_get_insn_slot(uprobe); 1599a6cb3f6dSOleg Nesterov if (!xol_vaddr) 1600a6cb3f6dSOleg Nesterov return -ENOMEM; 1601a6cb3f6dSOleg Nesterov 1602a6cb3f6dSOleg Nesterov utask->xol_vaddr = xol_vaddr; 1603a6cb3f6dSOleg Nesterov utask->vaddr = bp_vaddr; 1604a6cb3f6dSOleg Nesterov 1605aba51024SOleg Nesterov err = arch_uprobe_pre_xol(&uprobe->arch, regs); 1606aba51024SOleg Nesterov if (unlikely(err)) { 1607aba51024SOleg Nesterov xol_free_insn_slot(current); 1608aba51024SOleg Nesterov return err; 1609aba51024SOleg Nesterov } 1610aba51024SOleg Nesterov 1611608e7427SOleg Nesterov utask->active_uprobe = uprobe; 1612608e7427SOleg Nesterov utask->state = UTASK_SSTEP; 1613aba51024SOleg Nesterov return 0; 16140326f5a9SSrikar Dronamraju } 16150326f5a9SSrikar Dronamraju 16160326f5a9SSrikar Dronamraju /* 16170326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 16180326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 16190326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 16200326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 16210326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 16220326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 16230326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 16240326f5a9SSrikar Dronamraju */ 16250326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 16260326f5a9SSrikar Dronamraju { 16270326f5a9SSrikar Dronamraju struct task_struct *t = current; 16280326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 16290326f5a9SSrikar Dronamraju 16300326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 16310326f5a9SSrikar Dronamraju return false; 16320326f5a9SSrikar Dronamraju 16330326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 16340326f5a9SSrikar Dronamraju 16350326f5a9SSrikar Dronamraju if (signal_pending(t)) { 16360326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 16370326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 16380326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 16390326f5a9SSrikar Dronamraju 16400326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 16410326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 16420326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 16430326f5a9SSrikar Dronamraju } 16440326f5a9SSrikar Dronamraju } 16450326f5a9SSrikar Dronamraju 16460326f5a9SSrikar Dronamraju return true; 16470326f5a9SSrikar Dronamraju } 16480326f5a9SSrikar Dronamraju 1649499a4f3eSOleg Nesterov static void mmf_recalc_uprobes(struct mm_struct *mm) 1650499a4f3eSOleg Nesterov { 1651499a4f3eSOleg Nesterov struct vm_area_struct *vma; 1652499a4f3eSOleg Nesterov 1653499a4f3eSOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 1654499a4f3eSOleg Nesterov if (!valid_vma(vma, false)) 1655499a4f3eSOleg Nesterov continue; 1656499a4f3eSOleg Nesterov /* 1657499a4f3eSOleg Nesterov * This is not strictly accurate, we can race with 1658499a4f3eSOleg Nesterov * uprobe_unregister() and see the already removed 1659499a4f3eSOleg Nesterov * uprobe if delete_uprobe() was not yet called. 166063633cbfSOleg Nesterov * Or this uprobe can be filtered out. 1661499a4f3eSOleg Nesterov */ 1662499a4f3eSOleg Nesterov if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) 1663499a4f3eSOleg Nesterov return; 1664499a4f3eSOleg Nesterov } 1665499a4f3eSOleg Nesterov 1666499a4f3eSOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 1667499a4f3eSOleg Nesterov } 1668499a4f3eSOleg Nesterov 16690908ad6eSAnanth N Mavinakayanahalli static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) 1670ec75fba9SOleg Nesterov { 1671ec75fba9SOleg Nesterov struct page *page; 1672ec75fba9SOleg Nesterov uprobe_opcode_t opcode; 1673ec75fba9SOleg Nesterov int result; 1674ec75fba9SOleg Nesterov 1675ec75fba9SOleg Nesterov pagefault_disable(); 1676ec75fba9SOleg Nesterov result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, 1677ec75fba9SOleg Nesterov sizeof(opcode)); 1678ec75fba9SOleg Nesterov pagefault_enable(); 1679ec75fba9SOleg Nesterov 1680ec75fba9SOleg Nesterov if (likely(result == 0)) 1681ec75fba9SOleg Nesterov goto out; 1682ec75fba9SOleg Nesterov 1683ec75fba9SOleg Nesterov result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); 1684ec75fba9SOleg Nesterov if (result < 0) 1685ec75fba9SOleg Nesterov return result; 1686ec75fba9SOleg Nesterov 1687ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 1688ec75fba9SOleg Nesterov put_page(page); 1689ec75fba9SOleg Nesterov out: 16900908ad6eSAnanth N Mavinakayanahalli /* This needs to return true for any variant of the trap insn */ 16910908ad6eSAnanth N Mavinakayanahalli return is_trap_insn(&opcode); 1692ec75fba9SOleg Nesterov } 1693ec75fba9SOleg Nesterov 1694d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 16950326f5a9SSrikar Dronamraju { 16963a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 16973a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 16980326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 16990326f5a9SSrikar Dronamraju 17000326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 17010326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 17023a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 17033a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 1704f281769eSOleg Nesterov struct inode *inode = file_inode(vma->vm_file); 1705cb113b47SOleg Nesterov loff_t offset = vaddr_to_offset(vma, bp_vaddr); 17060326f5a9SSrikar Dronamraju 17070326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 17080326f5a9SSrikar Dronamraju } 1709d790d346SOleg Nesterov 1710d790d346SOleg Nesterov if (!uprobe) 17110908ad6eSAnanth N Mavinakayanahalli *is_swbp = is_trap_at_addr(mm, bp_vaddr); 1712d790d346SOleg Nesterov } else { 1713d790d346SOleg Nesterov *is_swbp = -EFAULT; 17143a9ea052SOleg Nesterov } 1715499a4f3eSOleg Nesterov 1716499a4f3eSOleg Nesterov if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) 1717499a4f3eSOleg Nesterov mmf_recalc_uprobes(mm); 17180326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 17190326f5a9SSrikar Dronamraju 17203a9ea052SOleg Nesterov return uprobe; 17213a9ea052SOleg Nesterov } 17223a9ea052SOleg Nesterov 1723da1816b1SOleg Nesterov static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 1724da1816b1SOleg Nesterov { 1725da1816b1SOleg Nesterov struct uprobe_consumer *uc; 1726da1816b1SOleg Nesterov int remove = UPROBE_HANDLER_REMOVE; 17270dfd0eb8SAnton Arapov bool need_prep = false; /* prepare return uprobe, when needed */ 1728da1816b1SOleg Nesterov 1729da1816b1SOleg Nesterov down_read(&uprobe->register_rwsem); 1730da1816b1SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 1731ea024870SAnton Arapov int rc = 0; 1732da1816b1SOleg Nesterov 1733ea024870SAnton Arapov if (uc->handler) { 1734ea024870SAnton Arapov rc = uc->handler(uc, regs); 1735da1816b1SOleg Nesterov WARN(rc & ~UPROBE_HANDLER_MASK, 1736da1816b1SOleg Nesterov "bad rc=0x%x from %pf()\n", rc, uc->handler); 1737ea024870SAnton Arapov } 17380dfd0eb8SAnton Arapov 17390dfd0eb8SAnton Arapov if (uc->ret_handler) 17400dfd0eb8SAnton Arapov need_prep = true; 17410dfd0eb8SAnton Arapov 1742da1816b1SOleg Nesterov remove &= rc; 1743da1816b1SOleg Nesterov } 1744da1816b1SOleg Nesterov 17450dfd0eb8SAnton Arapov if (need_prep && !remove) 17460dfd0eb8SAnton Arapov prepare_uretprobe(uprobe, regs); /* put bp at return */ 17470dfd0eb8SAnton Arapov 1748da1816b1SOleg Nesterov if (remove && uprobe->consumers) { 1749da1816b1SOleg Nesterov WARN_ON(!uprobe_is_active(uprobe)); 1750da1816b1SOleg Nesterov unapply_uprobe(uprobe, current->mm); 1751da1816b1SOleg Nesterov } 1752da1816b1SOleg Nesterov up_read(&uprobe->register_rwsem); 1753da1816b1SOleg Nesterov } 1754da1816b1SOleg Nesterov 1755fec8898dSAnton Arapov static void 1756fec8898dSAnton Arapov handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) 1757fec8898dSAnton Arapov { 1758fec8898dSAnton Arapov struct uprobe *uprobe = ri->uprobe; 1759fec8898dSAnton Arapov struct uprobe_consumer *uc; 1760fec8898dSAnton Arapov 1761fec8898dSAnton Arapov down_read(&uprobe->register_rwsem); 1762fec8898dSAnton Arapov for (uc = uprobe->consumers; uc; uc = uc->next) { 1763fec8898dSAnton Arapov if (uc->ret_handler) 1764fec8898dSAnton Arapov uc->ret_handler(uc, ri->func, regs); 1765fec8898dSAnton Arapov } 1766fec8898dSAnton Arapov up_read(&uprobe->register_rwsem); 1767fec8898dSAnton Arapov } 1768fec8898dSAnton Arapov 17690b5256c7SOleg Nesterov static void handle_trampoline(struct pt_regs *regs) 1770fec8898dSAnton Arapov { 1771fec8898dSAnton Arapov struct uprobe_task *utask; 17722bb5e840SOleg Nesterov struct return_instance *ri; 1773fec8898dSAnton Arapov bool chained; 1774fec8898dSAnton Arapov 1775fec8898dSAnton Arapov utask = current->utask; 1776fec8898dSAnton Arapov if (!utask) 17770b5256c7SOleg Nesterov goto sigill; 1778fec8898dSAnton Arapov 1779fec8898dSAnton Arapov ri = utask->return_instances; 1780fec8898dSAnton Arapov if (!ri) 17810b5256c7SOleg Nesterov goto sigill; 1782fec8898dSAnton Arapov 1783fec8898dSAnton Arapov /* 1784fec8898dSAnton Arapov * TODO: we should throw out return_instance's invalidated by 1785fec8898dSAnton Arapov * longjmp(), currently we assume that the probed function always 1786fec8898dSAnton Arapov * returns. 1787fec8898dSAnton Arapov */ 1788fec8898dSAnton Arapov instruction_pointer_set(regs, ri->orig_ret_vaddr); 1789fec8898dSAnton Arapov 1790fec8898dSAnton Arapov for (;;) { 1791fec8898dSAnton Arapov handle_uretprobe_chain(ri, regs); 1792fec8898dSAnton Arapov 1793fec8898dSAnton Arapov chained = ri->chained; 17942bb5e840SOleg Nesterov ri = free_ret_instance(ri); 1795878b5a6eSOleg Nesterov utask->depth--; 1796fec8898dSAnton Arapov 1797fec8898dSAnton Arapov if (!chained) 1798fec8898dSAnton Arapov break; 1799fec8898dSAnton Arapov BUG_ON(!ri); 1800fec8898dSAnton Arapov } 1801fec8898dSAnton Arapov 1802fec8898dSAnton Arapov utask->return_instances = ri; 18030b5256c7SOleg Nesterov return; 1804fec8898dSAnton Arapov 18050b5256c7SOleg Nesterov sigill: 18060b5256c7SOleg Nesterov uprobe_warn(current, "handle uretprobe, sending SIGILL."); 18070b5256c7SOleg Nesterov force_sig_info(SIGILL, SEND_SIG_FORCED, current); 18080b5256c7SOleg Nesterov 1809fec8898dSAnton Arapov } 1810fec8898dSAnton Arapov 18116fe50a28SDavid A. Long bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) 18126fe50a28SDavid A. Long { 18136fe50a28SDavid A. Long return false; 18146fe50a28SDavid A. Long } 18156fe50a28SDavid A. Long 18163a9ea052SOleg Nesterov /* 18173a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 18183a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 18193a9ea052SOleg Nesterov */ 18203a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 18213a9ea052SOleg Nesterov { 18223a9ea052SOleg Nesterov struct uprobe *uprobe; 18233a9ea052SOleg Nesterov unsigned long bp_vaddr; 182456bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 18253a9ea052SOleg Nesterov 18263a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 18270b5256c7SOleg Nesterov if (bp_vaddr == get_trampoline_vaddr()) 18280b5256c7SOleg Nesterov return handle_trampoline(regs); 1829fec8898dSAnton Arapov 1830fec8898dSAnton Arapov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 18310326f5a9SSrikar Dronamraju if (!uprobe) { 183256bb4cf6SOleg Nesterov if (is_swbp > 0) { 18330326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 18340326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 183556bb4cf6SOleg Nesterov } else { 183656bb4cf6SOleg Nesterov /* 183756bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 183856bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 183956bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 184056bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 184156bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 184256bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 184356bb4cf6SOleg Nesterov */ 184456bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 184556bb4cf6SOleg Nesterov } 18460326f5a9SSrikar Dronamraju return; 18470326f5a9SSrikar Dronamraju } 184874e59dfcSOleg Nesterov 184974e59dfcSOleg Nesterov /* change it in advance for ->handler() and restart */ 185074e59dfcSOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 185174e59dfcSOleg Nesterov 1852142b18ddSOleg Nesterov /* 1853142b18ddSOleg Nesterov * TODO: move copy_insn/etc into _register and remove this hack. 1854142b18ddSOleg Nesterov * After we hit the bp, _unregister + _register can install the 1855142b18ddSOleg Nesterov * new and not-yet-analyzed uprobe at the same address, restart. 1856142b18ddSOleg Nesterov */ 1857142b18ddSOleg Nesterov smp_rmb(); /* pairs with wmb() in install_breakpoint() */ 185871434f2fSOleg Nesterov if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) 185974e59dfcSOleg Nesterov goto out; 18600326f5a9SSrikar Dronamraju 186172fd293aSOleg Nesterov /* Tracing handlers use ->utask to communicate with fetch methods */ 186272fd293aSOleg Nesterov if (!get_utask()) 186372fd293aSOleg Nesterov goto out; 186472fd293aSOleg Nesterov 18656fe50a28SDavid A. Long if (arch_uprobe_ignore(&uprobe->arch, regs)) 18666fe50a28SDavid A. Long goto out; 18676fe50a28SDavid A. Long 18680326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 18696fe50a28SDavid A. Long 18708a6b1732SOleg Nesterov if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 18710578a970SOleg Nesterov goto out; 18720326f5a9SSrikar Dronamraju 1873608e7427SOleg Nesterov if (!pre_ssout(uprobe, regs, bp_vaddr)) 18740326f5a9SSrikar Dronamraju return; 18750326f5a9SSrikar Dronamraju 18768a6b1732SOleg Nesterov /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ 18770578a970SOleg Nesterov out: 18780326f5a9SSrikar Dronamraju put_uprobe(uprobe); 18790326f5a9SSrikar Dronamraju } 18800326f5a9SSrikar Dronamraju 18810326f5a9SSrikar Dronamraju /* 18820326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 18830326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 18840326f5a9SSrikar Dronamraju */ 18850326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 18860326f5a9SSrikar Dronamraju { 18870326f5a9SSrikar Dronamraju struct uprobe *uprobe; 1888014940baSOleg Nesterov int err = 0; 18890326f5a9SSrikar Dronamraju 18900326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 18910326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 1892014940baSOleg Nesterov err = arch_uprobe_post_xol(&uprobe->arch, regs); 18930326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 18940326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 18950326f5a9SSrikar Dronamraju else 18960326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 18970326f5a9SSrikar Dronamraju 18980326f5a9SSrikar Dronamraju put_uprobe(uprobe); 18990326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 19000326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 1901d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 19020326f5a9SSrikar Dronamraju 19030326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 19040326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 19050326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 1906014940baSOleg Nesterov 1907014940baSOleg Nesterov if (unlikely(err)) { 1908014940baSOleg Nesterov uprobe_warn(current, "execute the probed insn, sending SIGILL."); 1909014940baSOleg Nesterov force_sig_info(SIGILL, SEND_SIG_FORCED, current); 1910014940baSOleg Nesterov } 19110326f5a9SSrikar Dronamraju } 19120326f5a9SSrikar Dronamraju 19130326f5a9SSrikar Dronamraju /* 19141b08e907SOleg Nesterov * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and 19151b08e907SOleg Nesterov * allows the thread to return from interrupt. After that handle_swbp() 19161b08e907SOleg Nesterov * sets utask->active_uprobe. 19170326f5a9SSrikar Dronamraju * 19181b08e907SOleg Nesterov * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag 19191b08e907SOleg Nesterov * and allows the thread to return from interrupt. 19200326f5a9SSrikar Dronamraju * 19210326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 19220326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 19230326f5a9SSrikar Dronamraju */ 19240326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 19250326f5a9SSrikar Dronamraju { 19260326f5a9SSrikar Dronamraju struct uprobe_task *utask; 19270326f5a9SSrikar Dronamraju 1928db023ea5SOleg Nesterov clear_thread_flag(TIF_UPROBE); 1929db023ea5SOleg Nesterov 19300326f5a9SSrikar Dronamraju utask = current->utask; 19311b08e907SOleg Nesterov if (utask && utask->active_uprobe) 19320326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 19331b08e907SOleg Nesterov else 19341b08e907SOleg Nesterov handle_swbp(regs); 19350326f5a9SSrikar Dronamraju } 19360326f5a9SSrikar Dronamraju 19370326f5a9SSrikar Dronamraju /* 19380326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 19390326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 19400326f5a9SSrikar Dronamraju */ 19410326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 19420326f5a9SSrikar Dronamraju { 19430dfd0eb8SAnton Arapov if (!current->mm) 19440dfd0eb8SAnton Arapov return 0; 19450dfd0eb8SAnton Arapov 19460dfd0eb8SAnton Arapov if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && 19470dfd0eb8SAnton Arapov (!current->utask || !current->utask->return_instances)) 19480326f5a9SSrikar Dronamraju return 0; 19490326f5a9SSrikar Dronamraju 19500326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 19510326f5a9SSrikar Dronamraju return 1; 19520326f5a9SSrikar Dronamraju } 19530326f5a9SSrikar Dronamraju 19540326f5a9SSrikar Dronamraju /* 19550326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 19560326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 19570326f5a9SSrikar Dronamraju */ 19580326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 19590326f5a9SSrikar Dronamraju { 19600326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 19610326f5a9SSrikar Dronamraju 19620326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 19630326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 19640326f5a9SSrikar Dronamraju return 0; 19650326f5a9SSrikar Dronamraju 19660326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 19670326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 19680326f5a9SSrikar Dronamraju return 1; 19690326f5a9SSrikar Dronamraju } 19700326f5a9SSrikar Dronamraju 19710326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 19720326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 19730326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 19740326f5a9SSrikar Dronamraju }; 19750326f5a9SSrikar Dronamraju 1976a5f4374aSIngo Molnar static int __init init_uprobes(void) 1977a5f4374aSIngo Molnar { 1978a5f4374aSIngo Molnar int i; 1979a5f4374aSIngo Molnar 198066d06dffSOleg Nesterov for (i = 0; i < UPROBES_HASH_SZ; i++) 1981a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 19820326f5a9SSrikar Dronamraju 198332cdba1eSOleg Nesterov if (percpu_init_rwsem(&dup_mmap_sem)) 198432cdba1eSOleg Nesterov return -ENOMEM; 198532cdba1eSOleg Nesterov 19860326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 1987a5f4374aSIngo Molnar } 1988736e89d9SOleg Nesterov __initcall(init_uprobes); 1989