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 2290eec103SPeter Zijlstra * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra 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 89a5f4374aSIngo Molnar /* 90ad439356SOleg Nesterov * Execute out of line area: anonymous executable mapping installed 91ad439356SOleg Nesterov * by the probed task to execute the copy of the original instruction 92ad439356SOleg Nesterov * mangled by set_swbp(). 93ad439356SOleg Nesterov * 94c912dae6SOleg Nesterov * On a breakpoint hit, thread contests for a slot. It frees the 95c912dae6SOleg Nesterov * slot after singlestep. Currently a fixed number of slots are 96c912dae6SOleg Nesterov * allocated. 97c912dae6SOleg Nesterov */ 98c912dae6SOleg Nesterov struct xol_area { 99c912dae6SOleg Nesterov wait_queue_head_t wq; /* if all slots are busy */ 100c912dae6SOleg Nesterov atomic_t slot_count; /* number of in-use slots */ 101c912dae6SOleg Nesterov unsigned long *bitmap; /* 0 = free slot */ 102c912dae6SOleg Nesterov 103704bde3cSOleg Nesterov struct vm_special_mapping xol_mapping; 104704bde3cSOleg Nesterov struct page *pages[2]; 105c912dae6SOleg Nesterov /* 106c912dae6SOleg Nesterov * We keep the vma's vm_start rather than a pointer to the vma 107c912dae6SOleg Nesterov * itself. The probed process or a naughty kernel module could make 108c912dae6SOleg Nesterov * the vma go away, and we must handle that reasonably gracefully. 109c912dae6SOleg Nesterov */ 110c912dae6SOleg Nesterov unsigned long vaddr; /* Page(s) of instruction slots */ 111c912dae6SOleg Nesterov }; 112c912dae6SOleg Nesterov 113c912dae6SOleg Nesterov /* 114a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 115a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 116a5f4374aSIngo Molnar * changed after breakpoint was inserted. 117a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 118a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 119a5f4374aSIngo Molnar * executable vma. 120a5f4374aSIngo Molnar */ 121a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 122a5f4374aSIngo Molnar { 12313f59c5eSOleg Nesterov vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; 124a5f4374aSIngo Molnar 125e40cfce6SOleg Nesterov if (is_register) 126e40cfce6SOleg Nesterov flags |= VM_WRITE; 127a5f4374aSIngo Molnar 128e40cfce6SOleg Nesterov return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; 129a5f4374aSIngo Molnar } 130a5f4374aSIngo Molnar 13157683f72SOleg Nesterov static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) 132a5f4374aSIngo Molnar { 13357683f72SOleg Nesterov return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); 134a5f4374aSIngo Molnar } 135a5f4374aSIngo Molnar 136cb113b47SOleg Nesterov static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) 137cb113b47SOleg Nesterov { 138cb113b47SOleg Nesterov return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); 139cb113b47SOleg Nesterov } 140cb113b47SOleg Nesterov 141a5f4374aSIngo Molnar /** 142a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 143a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 144a5f4374aSIngo Molnar * 145a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 146c517ee74SOleg Nesterov * @addr: address the old @page is mapped at 147a5f4374aSIngo Molnar * @page: the cowed page we are replacing by kpage 148a5f4374aSIngo Molnar * @kpage: the modified page we replace page by 149a5f4374aSIngo Molnar * 150a5f4374aSIngo Molnar * Returns 0 on success, -EFAULT on failure. 151a5f4374aSIngo Molnar */ 152c517ee74SOleg Nesterov static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 153bdfaa2eeSOleg Nesterov struct page *old_page, struct page *new_page) 154a5f4374aSIngo Molnar { 155a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 1565323ce71SOleg Nesterov spinlock_t *ptl; 1575323ce71SOleg Nesterov pte_t *ptep; 1589f92448cSOleg Nesterov int err; 1596bdb913fSHaggai Eran /* For mmu_notifiers */ 1606bdb913fSHaggai Eran const unsigned long mmun_start = addr; 1616bdb913fSHaggai Eran const unsigned long mmun_end = addr + PAGE_SIZE; 16200501b53SJohannes Weiner struct mem_cgroup *memcg; 16300501b53SJohannes Weiner 164bdfaa2eeSOleg Nesterov err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg, 165f627c2f5SKirill A. Shutemov false); 16600501b53SJohannes Weiner if (err) 16700501b53SJohannes Weiner return err; 168a5f4374aSIngo Molnar 169194f8dcbSOleg Nesterov /* For try_to_free_swap() and munlock_vma_page() below */ 170bdfaa2eeSOleg Nesterov lock_page(old_page); 1719f92448cSOleg Nesterov 1726bdb913fSHaggai Eran mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 1739f92448cSOleg Nesterov err = -EAGAIN; 174bdfaa2eeSOleg Nesterov ptep = page_check_address(old_page, mm, addr, &ptl, 0); 1756c4687ccSOleg Nesterov if (!ptep) { 176bdfaa2eeSOleg Nesterov mem_cgroup_cancel_charge(new_page, memcg, false); 1779f92448cSOleg Nesterov goto unlock; 1786c4687ccSOleg Nesterov } 179a5f4374aSIngo Molnar 180bdfaa2eeSOleg Nesterov get_page(new_page); 181bdfaa2eeSOleg Nesterov page_add_new_anon_rmap(new_page, vma, addr, false); 182bdfaa2eeSOleg Nesterov mem_cgroup_commit_charge(new_page, memcg, false, false); 183bdfaa2eeSOleg Nesterov lru_cache_add_active_or_unevictable(new_page, vma); 184a5f4374aSIngo Molnar 185bdfaa2eeSOleg Nesterov if (!PageAnon(old_page)) { 186bdfaa2eeSOleg Nesterov dec_mm_counter(mm, mm_counter_file(old_page)); 1877396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1887396fa81SSrikar Dronamraju } 1897396fa81SSrikar Dronamraju 190a5f4374aSIngo Molnar flush_cache_page(vma, addr, pte_pfn(*ptep)); 19134ee645eSJoerg Roedel ptep_clear_flush_notify(vma, addr, ptep); 192bdfaa2eeSOleg Nesterov set_pte_at_notify(mm, addr, ptep, mk_pte(new_page, vma->vm_page_prot)); 193a5f4374aSIngo Molnar 194bdfaa2eeSOleg Nesterov page_remove_rmap(old_page, false); 195bdfaa2eeSOleg Nesterov if (!page_mapped(old_page)) 196bdfaa2eeSOleg Nesterov try_to_free_swap(old_page); 197a5f4374aSIngo Molnar pte_unmap_unlock(ptep, ptl); 198a5f4374aSIngo Molnar 199194f8dcbSOleg Nesterov if (vma->vm_flags & VM_LOCKED) 200bdfaa2eeSOleg Nesterov munlock_vma_page(old_page); 201bdfaa2eeSOleg Nesterov put_page(old_page); 202194f8dcbSOleg Nesterov 2039f92448cSOleg Nesterov err = 0; 2049f92448cSOleg Nesterov unlock: 2056bdb913fSHaggai Eran mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 206bdfaa2eeSOleg Nesterov unlock_page(old_page); 2079f92448cSOleg Nesterov return err; 208a5f4374aSIngo Molnar } 209a5f4374aSIngo Molnar 210a5f4374aSIngo Molnar /** 2115cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 212a5f4374aSIngo Molnar * @insn: instruction to be checked. 2135cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 214a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 215a5f4374aSIngo Molnar */ 2165cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 217a5f4374aSIngo Molnar { 2185cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 219a5f4374aSIngo Molnar } 220a5f4374aSIngo Molnar 2210908ad6eSAnanth N Mavinakayanahalli /** 2220908ad6eSAnanth N Mavinakayanahalli * is_trap_insn - check if instruction is breakpoint instruction. 2230908ad6eSAnanth N Mavinakayanahalli * @insn: instruction to be checked. 2240908ad6eSAnanth N Mavinakayanahalli * Default implementation of is_trap_insn 2250908ad6eSAnanth N Mavinakayanahalli * Returns true if @insn is a breakpoint instruction. 2260908ad6eSAnanth N Mavinakayanahalli * 2270908ad6eSAnanth N Mavinakayanahalli * This function is needed for the case where an architecture has multiple 2280908ad6eSAnanth N Mavinakayanahalli * trap instructions (like powerpc). 2290908ad6eSAnanth N Mavinakayanahalli */ 2300908ad6eSAnanth N Mavinakayanahalli bool __weak is_trap_insn(uprobe_opcode_t *insn) 2310908ad6eSAnanth N Mavinakayanahalli { 2320908ad6eSAnanth N Mavinakayanahalli return is_swbp_insn(insn); 2330908ad6eSAnanth N Mavinakayanahalli } 2340908ad6eSAnanth N Mavinakayanahalli 235ab0d805cSOleg Nesterov static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) 236cceb55aaSOleg Nesterov { 237cceb55aaSOleg Nesterov void *kaddr = kmap_atomic(page); 238ab0d805cSOleg Nesterov memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); 239cceb55aaSOleg Nesterov kunmap_atomic(kaddr); 240cceb55aaSOleg Nesterov } 241cceb55aaSOleg Nesterov 2425669cceeSOleg Nesterov static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) 2435669cceeSOleg Nesterov { 2445669cceeSOleg Nesterov void *kaddr = kmap_atomic(page); 2455669cceeSOleg Nesterov memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); 2465669cceeSOleg Nesterov kunmap_atomic(kaddr); 2475669cceeSOleg Nesterov } 2485669cceeSOleg Nesterov 249ed6f6a50SOleg Nesterov static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) 250ed6f6a50SOleg Nesterov { 251ed6f6a50SOleg Nesterov uprobe_opcode_t old_opcode; 252ed6f6a50SOleg Nesterov bool is_swbp; 253ed6f6a50SOleg Nesterov 2540908ad6eSAnanth N Mavinakayanahalli /* 2550908ad6eSAnanth N Mavinakayanahalli * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. 2560908ad6eSAnanth N Mavinakayanahalli * We do not check if it is any other 'trap variant' which could 2570908ad6eSAnanth N Mavinakayanahalli * be conditional trap instruction such as the one powerpc supports. 2580908ad6eSAnanth N Mavinakayanahalli * 2590908ad6eSAnanth N Mavinakayanahalli * The logic is that we do not care if the underlying instruction 2600908ad6eSAnanth N Mavinakayanahalli * is a trap variant; uprobes always wins over any other (gdb) 2610908ad6eSAnanth N Mavinakayanahalli * breakpoint. 2620908ad6eSAnanth N Mavinakayanahalli */ 263ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); 264ed6f6a50SOleg Nesterov is_swbp = is_swbp_insn(&old_opcode); 265ed6f6a50SOleg Nesterov 266ed6f6a50SOleg Nesterov if (is_swbp_insn(new_opcode)) { 267ed6f6a50SOleg Nesterov if (is_swbp) /* register: already installed? */ 268ed6f6a50SOleg Nesterov return 0; 269ed6f6a50SOleg Nesterov } else { 270ed6f6a50SOleg Nesterov if (!is_swbp) /* unregister: was it changed by us? */ 271076a365bSOleg Nesterov return 0; 272ed6f6a50SOleg Nesterov } 273ed6f6a50SOleg Nesterov 274ed6f6a50SOleg Nesterov return 1; 275ed6f6a50SOleg Nesterov } 276ed6f6a50SOleg Nesterov 277a5f4374aSIngo Molnar /* 278a5f4374aSIngo Molnar * NOTE: 279a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 280a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 281a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 2820908ad6eSAnanth N Mavinakayanahalli * supported by that architecture then we need to modify is_trap_at_addr and 283f72d41faSOleg Nesterov * uprobe_write_opcode accordingly. This would never be a problem for archs 284f72d41faSOleg Nesterov * that have fixed length instructions. 28529dedee0SOleg Nesterov * 286f72d41faSOleg Nesterov * uprobe_write_opcode - write the opcode at a given virtual address. 287a5f4374aSIngo Molnar * @mm: the probed process address space. 288a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 289a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 290a5f4374aSIngo Molnar * 29129dedee0SOleg Nesterov * Called with mm->mmap_sem held for write. 292a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 293a5f4374aSIngo Molnar */ 294f72d41faSOleg Nesterov int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, 295cceb55aaSOleg Nesterov uprobe_opcode_t opcode) 296a5f4374aSIngo Molnar { 297a5f4374aSIngo Molnar struct page *old_page, *new_page; 298a5f4374aSIngo Molnar struct vm_area_struct *vma; 299a5f4374aSIngo Molnar int ret; 300f403072cSOleg Nesterov 3015323ce71SOleg Nesterov retry: 302a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 303c8394812SKirill A. Shutemov ret = get_user_pages_remote(NULL, mm, vaddr, 1, 304c8394812SKirill A. Shutemov FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL); 305a5f4374aSIngo Molnar if (ret <= 0) 306a5f4374aSIngo Molnar return ret; 307a5f4374aSIngo Molnar 308ed6f6a50SOleg Nesterov ret = verify_opcode(old_page, vaddr, &opcode); 309ed6f6a50SOleg Nesterov if (ret <= 0) 310ed6f6a50SOleg Nesterov goto put_old; 311ed6f6a50SOleg Nesterov 31229dedee0SOleg Nesterov ret = anon_vma_prepare(vma); 31329dedee0SOleg Nesterov if (ret) 31429dedee0SOleg Nesterov goto put_old; 31529dedee0SOleg Nesterov 316a5f4374aSIngo Molnar ret = -ENOMEM; 317a5f4374aSIngo Molnar new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); 318a5f4374aSIngo Molnar if (!new_page) 3199f92448cSOleg Nesterov goto put_old; 320a5f4374aSIngo Molnar 32129dedee0SOleg Nesterov __SetPageUptodate(new_page); 3223f47107cSOleg Nesterov copy_highpage(new_page, old_page); 3233f47107cSOleg Nesterov copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 324a5f4374aSIngo Molnar 325c517ee74SOleg Nesterov ret = __replace_page(vma, vaddr, old_page, new_page); 32609cbfeafSKirill A. Shutemov put_page(new_page); 3279f92448cSOleg Nesterov put_old: 328a5f4374aSIngo Molnar put_page(old_page); 329a5f4374aSIngo Molnar 3305323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 3315323ce71SOleg Nesterov goto retry; 332a5f4374aSIngo Molnar return ret; 333a5f4374aSIngo Molnar } 334a5f4374aSIngo Molnar 335a5f4374aSIngo Molnar /** 3365cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 337e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 338a5f4374aSIngo Molnar * @mm: the probed process address space. 339a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 340a5f4374aSIngo Molnar * 341a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 342a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 343a5f4374aSIngo Molnar */ 3445cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 345a5f4374aSIngo Molnar { 346f72d41faSOleg Nesterov return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN); 347a5f4374aSIngo Molnar } 348a5f4374aSIngo Molnar 349a5f4374aSIngo Molnar /** 350a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 351a5f4374aSIngo Molnar * @mm: the probed process address space. 352e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 353a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 354a5f4374aSIngo Molnar * 355a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 356a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 357a5f4374aSIngo Molnar */ 358a5f4374aSIngo Molnar int __weak 359ded86e7cSOleg Nesterov set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 360a5f4374aSIngo Molnar { 361803200e2SOleg Nesterov return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn); 362a5f4374aSIngo Molnar } 363a5f4374aSIngo Molnar 364f231722aSOleg Nesterov static struct uprobe *get_uprobe(struct uprobe *uprobe) 365f231722aSOleg Nesterov { 366f231722aSOleg Nesterov atomic_inc(&uprobe->ref); 367f231722aSOleg Nesterov return uprobe; 368f231722aSOleg Nesterov } 369f231722aSOleg Nesterov 370f231722aSOleg Nesterov static void put_uprobe(struct uprobe *uprobe) 371f231722aSOleg Nesterov { 372f231722aSOleg Nesterov if (atomic_dec_and_test(&uprobe->ref)) 373f231722aSOleg Nesterov kfree(uprobe); 374f231722aSOleg Nesterov } 375f231722aSOleg Nesterov 376a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 377a5f4374aSIngo Molnar { 378a5f4374aSIngo Molnar if (l->inode < r->inode) 379a5f4374aSIngo Molnar return -1; 380a5f4374aSIngo Molnar 381a5f4374aSIngo Molnar if (l->inode > r->inode) 382a5f4374aSIngo Molnar return 1; 383a5f4374aSIngo Molnar 384a5f4374aSIngo Molnar if (l->offset < r->offset) 385a5f4374aSIngo Molnar return -1; 386a5f4374aSIngo Molnar 387a5f4374aSIngo Molnar if (l->offset > r->offset) 388a5f4374aSIngo Molnar return 1; 389a5f4374aSIngo Molnar 390a5f4374aSIngo Molnar return 0; 391a5f4374aSIngo Molnar } 392a5f4374aSIngo Molnar 393a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 394a5f4374aSIngo Molnar { 395a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 396a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 397a5f4374aSIngo Molnar struct uprobe *uprobe; 398a5f4374aSIngo Molnar int match; 399a5f4374aSIngo Molnar 400a5f4374aSIngo Molnar while (n) { 401a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 402a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 403f231722aSOleg Nesterov if (!match) 404f231722aSOleg Nesterov return get_uprobe(uprobe); 405a5f4374aSIngo Molnar 406a5f4374aSIngo Molnar if (match < 0) 407a5f4374aSIngo Molnar n = n->rb_left; 408a5f4374aSIngo Molnar else 409a5f4374aSIngo Molnar n = n->rb_right; 410a5f4374aSIngo Molnar } 411a5f4374aSIngo Molnar return NULL; 412a5f4374aSIngo Molnar } 413a5f4374aSIngo Molnar 414a5f4374aSIngo Molnar /* 415a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 416a5f4374aSIngo Molnar * Acquires uprobes_treelock 417a5f4374aSIngo Molnar */ 418a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 419a5f4374aSIngo Molnar { 420a5f4374aSIngo Molnar struct uprobe *uprobe; 421a5f4374aSIngo Molnar 4226f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 423a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 4246f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 425a5f4374aSIngo Molnar 426a5f4374aSIngo Molnar return uprobe; 427a5f4374aSIngo Molnar } 428a5f4374aSIngo Molnar 429a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 430a5f4374aSIngo Molnar { 431a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 432a5f4374aSIngo Molnar struct rb_node *parent = NULL; 433a5f4374aSIngo Molnar struct uprobe *u; 434a5f4374aSIngo Molnar int match; 435a5f4374aSIngo Molnar 436a5f4374aSIngo Molnar while (*p) { 437a5f4374aSIngo Molnar parent = *p; 438a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 439a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 440f231722aSOleg Nesterov if (!match) 441f231722aSOleg Nesterov return get_uprobe(u); 442a5f4374aSIngo Molnar 443a5f4374aSIngo Molnar if (match < 0) 444a5f4374aSIngo Molnar p = &parent->rb_left; 445a5f4374aSIngo Molnar else 446a5f4374aSIngo Molnar p = &parent->rb_right; 447a5f4374aSIngo Molnar 448a5f4374aSIngo Molnar } 449a5f4374aSIngo Molnar 450a5f4374aSIngo Molnar u = NULL; 451a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 452a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 453a5f4374aSIngo Molnar /* get access + creation ref */ 454a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 455a5f4374aSIngo Molnar 456a5f4374aSIngo Molnar return u; 457a5f4374aSIngo Molnar } 458a5f4374aSIngo Molnar 459a5f4374aSIngo Molnar /* 460a5f4374aSIngo Molnar * Acquire uprobes_treelock. 461a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 462a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 463a5f4374aSIngo Molnar * 464a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 465a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 466a5f4374aSIngo Molnar */ 467a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 468a5f4374aSIngo Molnar { 469a5f4374aSIngo Molnar struct uprobe *u; 470a5f4374aSIngo Molnar 4716f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 472a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 4736f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 474a5f4374aSIngo Molnar 475a5f4374aSIngo Molnar return u; 476a5f4374aSIngo Molnar } 477a5f4374aSIngo Molnar 478a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 479a5f4374aSIngo Molnar { 480a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 481a5f4374aSIngo Molnar 482a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 483a5f4374aSIngo Molnar if (!uprobe) 484a5f4374aSIngo Molnar return NULL; 485a5f4374aSIngo Molnar 486a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 487a5f4374aSIngo Molnar uprobe->offset = offset; 488e591c8d7SOleg Nesterov init_rwsem(&uprobe->register_rwsem); 489a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 490a5f4374aSIngo Molnar 491a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 492a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 493a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 494a5f4374aSIngo Molnar if (cur_uprobe) { 495a5f4374aSIngo Molnar kfree(uprobe); 496a5f4374aSIngo Molnar uprobe = cur_uprobe; 497a5f4374aSIngo Molnar iput(inode); 498a5f4374aSIngo Molnar } 499a5f4374aSIngo Molnar 500a5f4374aSIngo Molnar return uprobe; 501a5f4374aSIngo Molnar } 502a5f4374aSIngo Molnar 5039a98e03cSOleg Nesterov static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 504a5f4374aSIngo Molnar { 505a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 506e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 507e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 508a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 509a5f4374aSIngo Molnar } 510a5f4374aSIngo Molnar 511a5f4374aSIngo Molnar /* 512e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 513e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 514a5f4374aSIngo Molnar * or return false. 515a5f4374aSIngo Molnar */ 516e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 517a5f4374aSIngo Molnar { 518a5f4374aSIngo Molnar struct uprobe_consumer **con; 519a5f4374aSIngo Molnar bool ret = false; 520a5f4374aSIngo Molnar 521a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 522a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 523e3343e6aSSrikar Dronamraju if (*con == uc) { 524e3343e6aSSrikar Dronamraju *con = uc->next; 525a5f4374aSIngo Molnar ret = true; 526a5f4374aSIngo Molnar break; 527a5f4374aSIngo Molnar } 528a5f4374aSIngo Molnar } 529a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 530a5f4374aSIngo Molnar 531a5f4374aSIngo Molnar return ret; 532a5f4374aSIngo Molnar } 533a5f4374aSIngo Molnar 5342ded0980SOleg Nesterov static int __copy_insn(struct address_space *mapping, struct file *filp, 5352ded0980SOleg Nesterov void *insn, int nbytes, loff_t offset) 536a5f4374aSIngo Molnar { 537a5f4374aSIngo Molnar struct page *page; 538a5f4374aSIngo Molnar /* 53940814f68SOleg Nesterov * Ensure that the page that has the original instruction is populated 54040814f68SOleg Nesterov * and in page-cache. If ->readpage == NULL it must be shmem_mapping(), 54140814f68SOleg Nesterov * see uprobe_register(). 542a5f4374aSIngo Molnar */ 54340814f68SOleg Nesterov if (mapping->a_ops->readpage) 54409cbfeafSKirill A. Shutemov page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp); 54540814f68SOleg Nesterov else 54609cbfeafSKirill A. Shutemov page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); 547a5f4374aSIngo Molnar if (IS_ERR(page)) 548a5f4374aSIngo Molnar return PTR_ERR(page); 549a5f4374aSIngo Molnar 5502edb7b55SOleg Nesterov copy_from_page(page, offset, insn, nbytes); 55109cbfeafSKirill A. Shutemov put_page(page); 552a5f4374aSIngo Molnar 553a5f4374aSIngo Molnar return 0; 554a5f4374aSIngo Molnar } 555a5f4374aSIngo Molnar 556d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 557a5f4374aSIngo Molnar { 5582ded0980SOleg Nesterov struct address_space *mapping = uprobe->inode->i_mapping; 5592ded0980SOleg Nesterov loff_t offs = uprobe->offset; 560803200e2SOleg Nesterov void *insn = &uprobe->arch.insn; 561803200e2SOleg Nesterov int size = sizeof(uprobe->arch.insn); 5622ded0980SOleg Nesterov int len, err = -EIO; 563a5f4374aSIngo Molnar 5642ded0980SOleg Nesterov /* Copy only available bytes, -EIO if nothing was read */ 5652ded0980SOleg Nesterov do { 5662ded0980SOleg Nesterov if (offs >= i_size_read(uprobe->inode)) 5672ded0980SOleg Nesterov break; 568a5f4374aSIngo Molnar 5692ded0980SOleg Nesterov len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); 5702ded0980SOleg Nesterov err = __copy_insn(mapping, filp, insn, len, offs); 571fc36f595SOleg Nesterov if (err) 5722ded0980SOleg Nesterov break; 5732ded0980SOleg Nesterov 5742ded0980SOleg Nesterov insn += len; 5752ded0980SOleg Nesterov offs += len; 5762ded0980SOleg Nesterov size -= len; 5772ded0980SOleg Nesterov } while (size); 5782ded0980SOleg Nesterov 579fc36f595SOleg Nesterov return err; 580a5f4374aSIngo Molnar } 581a5f4374aSIngo Molnar 582cb9a19feSOleg Nesterov static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 583cb9a19feSOleg Nesterov struct mm_struct *mm, unsigned long vaddr) 584cb9a19feSOleg Nesterov { 585cb9a19feSOleg Nesterov int ret = 0; 586cb9a19feSOleg Nesterov 58771434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 588cb9a19feSOleg Nesterov return ret; 589cb9a19feSOleg Nesterov 590d4d3ccc6SOleg Nesterov /* TODO: move this into _register, until then we abuse this sem. */ 591d4d3ccc6SOleg Nesterov down_write(&uprobe->consumer_rwsem); 59271434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 5934710f05fSOleg Nesterov goto out; 5944710f05fSOleg Nesterov 595cb9a19feSOleg Nesterov ret = copy_insn(uprobe, file); 596cb9a19feSOleg Nesterov if (ret) 597cb9a19feSOleg Nesterov goto out; 598cb9a19feSOleg Nesterov 599cb9a19feSOleg Nesterov ret = -ENOTSUPP; 600803200e2SOleg Nesterov if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) 601cb9a19feSOleg Nesterov goto out; 602cb9a19feSOleg Nesterov 603cb9a19feSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 604cb9a19feSOleg Nesterov if (ret) 605cb9a19feSOleg Nesterov goto out; 606cb9a19feSOleg Nesterov 607f72d41faSOleg Nesterov /* uprobe_write_opcode() assumes we don't cross page boundary */ 608cb9a19feSOleg Nesterov BUG_ON((uprobe->offset & ~PAGE_MASK) + 609cb9a19feSOleg Nesterov UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 610cb9a19feSOleg Nesterov 611cb9a19feSOleg Nesterov smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ 61271434f2fSOleg Nesterov set_bit(UPROBE_COPY_INSN, &uprobe->flags); 613cb9a19feSOleg Nesterov 614cb9a19feSOleg Nesterov out: 615d4d3ccc6SOleg Nesterov up_write(&uprobe->consumer_rwsem); 6164710f05fSOleg Nesterov 617cb9a19feSOleg Nesterov return ret; 618cb9a19feSOleg Nesterov } 619cb9a19feSOleg Nesterov 6208a7f2fa0SOleg Nesterov static inline bool consumer_filter(struct uprobe_consumer *uc, 6218a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 622806a98bdSOleg Nesterov { 6238a7f2fa0SOleg Nesterov return !uc->filter || uc->filter(uc, ctx, mm); 624806a98bdSOleg Nesterov } 625806a98bdSOleg Nesterov 6268a7f2fa0SOleg Nesterov static bool filter_chain(struct uprobe *uprobe, 6278a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 62863633cbfSOleg Nesterov { 6291ff6fee5SOleg Nesterov struct uprobe_consumer *uc; 6301ff6fee5SOleg Nesterov bool ret = false; 6311ff6fee5SOleg Nesterov 6321ff6fee5SOleg Nesterov down_read(&uprobe->consumer_rwsem); 6331ff6fee5SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 6348a7f2fa0SOleg Nesterov ret = consumer_filter(uc, ctx, mm); 6351ff6fee5SOleg Nesterov if (ret) 6361ff6fee5SOleg Nesterov break; 6371ff6fee5SOleg Nesterov } 6381ff6fee5SOleg Nesterov up_read(&uprobe->consumer_rwsem); 6391ff6fee5SOleg Nesterov 6401ff6fee5SOleg Nesterov return ret; 64163633cbfSOleg Nesterov } 64263633cbfSOleg Nesterov 643e3343e6aSSrikar Dronamraju static int 644e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 645816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 646a5f4374aSIngo Molnar { 647f8ac4ec9SOleg Nesterov bool first_uprobe; 648a5f4374aSIngo Molnar int ret; 649a5f4374aSIngo Molnar 650cb9a19feSOleg Nesterov ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); 651a5f4374aSIngo Molnar if (ret) 652a5f4374aSIngo Molnar return ret; 653a5f4374aSIngo Molnar 654f8ac4ec9SOleg Nesterov /* 655f8ac4ec9SOleg Nesterov * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), 656f8ac4ec9SOleg Nesterov * the task can hit this breakpoint right after __replace_page(). 657f8ac4ec9SOleg Nesterov */ 658f8ac4ec9SOleg Nesterov first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); 659f8ac4ec9SOleg Nesterov if (first_uprobe) 660f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &mm->flags); 661f8ac4ec9SOleg Nesterov 662816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 6639f68f672SOleg Nesterov if (!ret) 6649f68f672SOleg Nesterov clear_bit(MMF_RECALC_UPROBES, &mm->flags); 6659f68f672SOleg Nesterov else if (first_uprobe) 666f8ac4ec9SOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 667a5f4374aSIngo Molnar 668a5f4374aSIngo Molnar return ret; 669a5f4374aSIngo Molnar } 670a5f4374aSIngo Molnar 671076a365bSOleg Nesterov static int 672816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 673a5f4374aSIngo Molnar { 6749f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &mm->flags); 675076a365bSOleg Nesterov return set_orig_insn(&uprobe->arch, mm, vaddr); 676a5f4374aSIngo Molnar } 677a5f4374aSIngo Molnar 67806b7bcd8SOleg Nesterov static inline bool uprobe_is_active(struct uprobe *uprobe) 67906b7bcd8SOleg Nesterov { 68006b7bcd8SOleg Nesterov return !RB_EMPTY_NODE(&uprobe->rb_node); 68106b7bcd8SOleg Nesterov } 6820326f5a9SSrikar Dronamraju /* 683778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 684778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 685778b032dSOleg Nesterov * See find_active_uprobe(). 6860326f5a9SSrikar Dronamraju */ 687a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 688a5f4374aSIngo Molnar { 68906b7bcd8SOleg Nesterov if (WARN_ON(!uprobe_is_active(uprobe))) 69006b7bcd8SOleg Nesterov return; 69106b7bcd8SOleg Nesterov 6926f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 693a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 6946f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 69506b7bcd8SOleg Nesterov RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ 696a5f4374aSIngo Molnar iput(uprobe->inode); 697a5f4374aSIngo Molnar put_uprobe(uprobe); 698a5f4374aSIngo Molnar } 699a5f4374aSIngo Molnar 70026872090SOleg Nesterov struct map_info { 70126872090SOleg Nesterov struct map_info *next; 70226872090SOleg Nesterov struct mm_struct *mm; 703816c03fbSOleg Nesterov unsigned long vaddr; 70426872090SOleg Nesterov }; 70526872090SOleg Nesterov 70626872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 707a5f4374aSIngo Molnar { 70826872090SOleg Nesterov struct map_info *next = info->next; 70926872090SOleg Nesterov kfree(info); 71026872090SOleg Nesterov return next; 71126872090SOleg Nesterov } 71226872090SOleg Nesterov 71326872090SOleg Nesterov static struct map_info * 71426872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 71526872090SOleg Nesterov { 71626872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 717a5f4374aSIngo Molnar struct vm_area_struct *vma; 71826872090SOleg Nesterov struct map_info *curr = NULL; 71926872090SOleg Nesterov struct map_info *prev = NULL; 72026872090SOleg Nesterov struct map_info *info; 72126872090SOleg Nesterov int more = 0; 722a5f4374aSIngo Molnar 72326872090SOleg Nesterov again: 7244a23717aSDavidlohr Bueso i_mmap_lock_read(mapping); 7256b2dbba8SMichel Lespinasse vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { 726a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 727a5f4374aSIngo Molnar continue; 728a5f4374aSIngo Molnar 7297a5bfb66SOleg Nesterov if (!prev && !more) { 7307a5bfb66SOleg Nesterov /* 731c8c06efaSDavidlohr Bueso * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through 7327a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 7337a5bfb66SOleg Nesterov */ 7347a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 7357a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 7367a5bfb66SOleg Nesterov if (prev) 7377a5bfb66SOleg Nesterov prev->next = NULL; 7387a5bfb66SOleg Nesterov } 73926872090SOleg Nesterov if (!prev) { 74026872090SOleg Nesterov more++; 74126872090SOleg Nesterov continue; 742a5f4374aSIngo Molnar } 743a5f4374aSIngo Molnar 74426872090SOleg Nesterov if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) 74526872090SOleg Nesterov continue; 746a5f4374aSIngo Molnar 74726872090SOleg Nesterov info = prev; 74826872090SOleg Nesterov prev = prev->next; 74926872090SOleg Nesterov info->next = curr; 75026872090SOleg Nesterov curr = info; 75126872090SOleg Nesterov 75226872090SOleg Nesterov info->mm = vma->vm_mm; 75357683f72SOleg Nesterov info->vaddr = offset_to_vaddr(vma, offset); 754a5f4374aSIngo Molnar } 7554a23717aSDavidlohr Bueso i_mmap_unlock_read(mapping); 756a5f4374aSIngo Molnar 75726872090SOleg Nesterov if (!more) 75826872090SOleg Nesterov goto out; 759a5f4374aSIngo Molnar 76026872090SOleg Nesterov prev = curr; 76126872090SOleg Nesterov while (curr) { 76226872090SOleg Nesterov mmput(curr->mm); 76326872090SOleg Nesterov curr = curr->next; 76426872090SOleg Nesterov } 76526872090SOleg Nesterov 76626872090SOleg Nesterov do { 76726872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 76826872090SOleg Nesterov if (!info) { 76926872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 77026872090SOleg Nesterov goto out; 77126872090SOleg Nesterov } 77226872090SOleg Nesterov info->next = prev; 77326872090SOleg Nesterov prev = info; 77426872090SOleg Nesterov } while (--more); 77526872090SOleg Nesterov 77626872090SOleg Nesterov goto again; 77726872090SOleg Nesterov out: 77826872090SOleg Nesterov while (prev) 77926872090SOleg Nesterov prev = free_map_info(prev); 78026872090SOleg Nesterov return curr; 781a5f4374aSIngo Molnar } 782a5f4374aSIngo Molnar 783bdf8647cSOleg Nesterov static int 784bdf8647cSOleg Nesterov register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) 785a5f4374aSIngo Molnar { 786bdf8647cSOleg Nesterov bool is_register = !!new; 78726872090SOleg Nesterov struct map_info *info; 78826872090SOleg Nesterov int err = 0; 78926872090SOleg Nesterov 79032cdba1eSOleg Nesterov percpu_down_write(&dup_mmap_sem); 79126872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 79226872090SOleg Nesterov uprobe->offset, is_register); 79332cdba1eSOleg Nesterov if (IS_ERR(info)) { 79432cdba1eSOleg Nesterov err = PTR_ERR(info); 79532cdba1eSOleg Nesterov goto out; 79632cdba1eSOleg Nesterov } 79726872090SOleg Nesterov 79826872090SOleg Nesterov while (info) { 79926872090SOleg Nesterov struct mm_struct *mm = info->mm; 800a5f4374aSIngo Molnar struct vm_area_struct *vma; 801a5f4374aSIngo Molnar 802076a365bSOleg Nesterov if (err && is_register) 80326872090SOleg Nesterov goto free; 804a5f4374aSIngo Molnar 80577fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 806f4d6dfe5SOleg Nesterov vma = find_vma(mm, info->vaddr); 807f4d6dfe5SOleg Nesterov if (!vma || !valid_vma(vma, is_register) || 808f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 80926872090SOleg Nesterov goto unlock; 81026872090SOleg Nesterov 811f4d6dfe5SOleg Nesterov if (vma->vm_start > info->vaddr || 812f4d6dfe5SOleg Nesterov vaddr_to_offset(vma, info->vaddr) != uprobe->offset) 81326872090SOleg Nesterov goto unlock; 814a5f4374aSIngo Molnar 815806a98bdSOleg Nesterov if (is_register) { 816806a98bdSOleg Nesterov /* consult only the "caller", new consumer. */ 817bdf8647cSOleg Nesterov if (consumer_filter(new, 8188a7f2fa0SOleg Nesterov UPROBE_FILTER_REGISTER, mm)) 81926872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 820806a98bdSOleg Nesterov } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { 8218a7f2fa0SOleg Nesterov if (!filter_chain(uprobe, 8228a7f2fa0SOleg Nesterov UPROBE_FILTER_UNREGISTER, mm)) 823076a365bSOleg Nesterov err |= remove_breakpoint(uprobe, mm, info->vaddr); 824806a98bdSOleg Nesterov } 82578f74116SOleg Nesterov 82626872090SOleg Nesterov unlock: 82726872090SOleg Nesterov up_write(&mm->mmap_sem); 82826872090SOleg Nesterov free: 82926872090SOleg Nesterov mmput(mm); 83026872090SOleg Nesterov info = free_map_info(info); 831a5f4374aSIngo Molnar } 83232cdba1eSOleg Nesterov out: 83332cdba1eSOleg Nesterov percpu_up_write(&dup_mmap_sem); 83426872090SOleg Nesterov return err; 835a5f4374aSIngo Molnar } 836a5f4374aSIngo Molnar 8379a98e03cSOleg Nesterov static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) 838a5f4374aSIngo Molnar { 8399a98e03cSOleg Nesterov consumer_add(uprobe, uc); 840bdf8647cSOleg Nesterov return register_for_each_vma(uprobe, uc); 841a5f4374aSIngo Molnar } 842a5f4374aSIngo Molnar 84304aab9b2SOleg Nesterov static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) 844a5f4374aSIngo Molnar { 84504aab9b2SOleg Nesterov int err; 846a5f4374aSIngo Molnar 84706d07139SOleg Nesterov if (WARN_ON(!consumer_del(uprobe, uc))) 84804aab9b2SOleg Nesterov return; 84904aab9b2SOleg Nesterov 850bdf8647cSOleg Nesterov err = register_for_each_vma(uprobe, NULL); 851a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 852bb929284SOleg Nesterov if (!uprobe->consumers && !err) 85304aab9b2SOleg Nesterov delete_uprobe(uprobe); 85404aab9b2SOleg Nesterov } 855a5f4374aSIngo Molnar 856a5f4374aSIngo Molnar /* 857a5f4374aSIngo Molnar * uprobe_register - register a probe 858a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 859a5f4374aSIngo Molnar * @offset: offset from the start of the file. 860e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 861a5f4374aSIngo Molnar * 862a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 863a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 864a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 865a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 866a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 867e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 868a5f4374aSIngo Molnar * unregisters. 869a5f4374aSIngo Molnar * 870a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 871a5f4374aSIngo Molnar * else return 0 (success) 872a5f4374aSIngo Molnar */ 873e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 874a5f4374aSIngo Molnar { 875a5f4374aSIngo Molnar struct uprobe *uprobe; 876a5f4374aSIngo Molnar int ret; 877a5f4374aSIngo Molnar 878ea024870SAnton Arapov /* Uprobe must have at least one set consumer */ 879ea024870SAnton Arapov if (!uc->handler && !uc->ret_handler) 880ea024870SAnton Arapov return -EINVAL; 881ea024870SAnton Arapov 88240814f68SOleg Nesterov /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ 88340814f68SOleg Nesterov if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) 88441ccba02SOleg Nesterov return -EIO; 885f0744af7SOleg Nesterov /* Racy, just to catch the obvious mistakes */ 886a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 887a5f4374aSIngo Molnar return -EINVAL; 888a5f4374aSIngo Molnar 88966d06dffSOleg Nesterov retry: 890a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 89166d06dffSOleg Nesterov if (!uprobe) 89266d06dffSOleg Nesterov return -ENOMEM; 89366d06dffSOleg Nesterov /* 89466d06dffSOleg Nesterov * We can race with uprobe_unregister()->delete_uprobe(). 89566d06dffSOleg Nesterov * Check uprobe_is_active() and retry if it is false. 89666d06dffSOleg Nesterov */ 897e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 89866d06dffSOleg Nesterov ret = -EAGAIN; 89966d06dffSOleg Nesterov if (likely(uprobe_is_active(uprobe))) { 9009a98e03cSOleg Nesterov ret = __uprobe_register(uprobe, uc); 9019a98e03cSOleg Nesterov if (ret) 90204aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 903a5f4374aSIngo Molnar } 90466d06dffSOleg Nesterov up_write(&uprobe->register_rwsem); 905a5f4374aSIngo Molnar put_uprobe(uprobe); 906a5f4374aSIngo Molnar 90766d06dffSOleg Nesterov if (unlikely(ret == -EAGAIN)) 90866d06dffSOleg Nesterov goto retry; 909a5f4374aSIngo Molnar return ret; 910a5f4374aSIngo Molnar } 911e8440c14SJosh Stone EXPORT_SYMBOL_GPL(uprobe_register); 912a5f4374aSIngo Molnar 913a5f4374aSIngo Molnar /* 914bdf8647cSOleg Nesterov * uprobe_apply - unregister a already registered probe. 915bdf8647cSOleg Nesterov * @inode: the file in which the probe has to be removed. 916bdf8647cSOleg Nesterov * @offset: offset from the start of the file. 917bdf8647cSOleg Nesterov * @uc: consumer which wants to add more or remove some breakpoints 918bdf8647cSOleg Nesterov * @add: add or remove the breakpoints 919bdf8647cSOleg Nesterov */ 920bdf8647cSOleg Nesterov int uprobe_apply(struct inode *inode, loff_t offset, 921bdf8647cSOleg Nesterov struct uprobe_consumer *uc, bool add) 922bdf8647cSOleg Nesterov { 923bdf8647cSOleg Nesterov struct uprobe *uprobe; 924bdf8647cSOleg Nesterov struct uprobe_consumer *con; 925bdf8647cSOleg Nesterov int ret = -ENOENT; 926bdf8647cSOleg Nesterov 927bdf8647cSOleg Nesterov uprobe = find_uprobe(inode, offset); 92806d07139SOleg Nesterov if (WARN_ON(!uprobe)) 929bdf8647cSOleg Nesterov return ret; 930bdf8647cSOleg Nesterov 931bdf8647cSOleg Nesterov down_write(&uprobe->register_rwsem); 932bdf8647cSOleg Nesterov for (con = uprobe->consumers; con && con != uc ; con = con->next) 933bdf8647cSOleg Nesterov ; 934bdf8647cSOleg Nesterov if (con) 935bdf8647cSOleg Nesterov ret = register_for_each_vma(uprobe, add ? uc : NULL); 936bdf8647cSOleg Nesterov up_write(&uprobe->register_rwsem); 937bdf8647cSOleg Nesterov put_uprobe(uprobe); 938bdf8647cSOleg Nesterov 939bdf8647cSOleg Nesterov return ret; 940bdf8647cSOleg Nesterov } 941bdf8647cSOleg Nesterov 942bdf8647cSOleg Nesterov /* 943a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 944a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 945a5f4374aSIngo Molnar * @offset: offset from the start of the file. 946e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 947a5f4374aSIngo Molnar */ 948e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 949a5f4374aSIngo Molnar { 950a5f4374aSIngo Molnar struct uprobe *uprobe; 951a5f4374aSIngo Molnar 952a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 95306d07139SOleg Nesterov if (WARN_ON(!uprobe)) 954a5f4374aSIngo Molnar return; 955a5f4374aSIngo Molnar 956e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 95704aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 958e591c8d7SOleg Nesterov up_write(&uprobe->register_rwsem); 959a5f4374aSIngo Molnar put_uprobe(uprobe); 960a5f4374aSIngo Molnar } 961e8440c14SJosh Stone EXPORT_SYMBOL_GPL(uprobe_unregister); 962a5f4374aSIngo Molnar 963da1816b1SOleg Nesterov static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) 964da1816b1SOleg Nesterov { 965da1816b1SOleg Nesterov struct vm_area_struct *vma; 966da1816b1SOleg Nesterov int err = 0; 967da1816b1SOleg Nesterov 968da1816b1SOleg Nesterov down_read(&mm->mmap_sem); 969da1816b1SOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 970da1816b1SOleg Nesterov unsigned long vaddr; 971da1816b1SOleg Nesterov loff_t offset; 972da1816b1SOleg Nesterov 973da1816b1SOleg Nesterov if (!valid_vma(vma, false) || 974f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 975da1816b1SOleg Nesterov continue; 976da1816b1SOleg Nesterov 977da1816b1SOleg Nesterov offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; 978da1816b1SOleg Nesterov if (uprobe->offset < offset || 979da1816b1SOleg Nesterov uprobe->offset >= offset + vma->vm_end - vma->vm_start) 980da1816b1SOleg Nesterov continue; 981da1816b1SOleg Nesterov 982da1816b1SOleg Nesterov vaddr = offset_to_vaddr(vma, uprobe->offset); 983da1816b1SOleg Nesterov err |= remove_breakpoint(uprobe, mm, vaddr); 984da1816b1SOleg Nesterov } 985da1816b1SOleg Nesterov up_read(&mm->mmap_sem); 986da1816b1SOleg Nesterov 987da1816b1SOleg Nesterov return err; 988da1816b1SOleg Nesterov } 989da1816b1SOleg Nesterov 990891c3970SOleg Nesterov static struct rb_node * 991891c3970SOleg Nesterov find_node_in_range(struct inode *inode, loff_t min, loff_t max) 992a5f4374aSIngo Molnar { 993a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 994a5f4374aSIngo Molnar 995a5f4374aSIngo Molnar while (n) { 996891c3970SOleg Nesterov struct uprobe *u = rb_entry(n, struct uprobe, rb_node); 997a5f4374aSIngo Molnar 998891c3970SOleg Nesterov if (inode < u->inode) { 999a5f4374aSIngo Molnar n = n->rb_left; 1000891c3970SOleg Nesterov } else if (inode > u->inode) { 1001a5f4374aSIngo Molnar n = n->rb_right; 1002891c3970SOleg Nesterov } else { 1003891c3970SOleg Nesterov if (max < u->offset) 1004891c3970SOleg Nesterov n = n->rb_left; 1005891c3970SOleg Nesterov else if (min > u->offset) 1006891c3970SOleg Nesterov n = n->rb_right; 1007891c3970SOleg Nesterov else 1008891c3970SOleg Nesterov break; 1009891c3970SOleg Nesterov } 1010a5f4374aSIngo Molnar } 1011a5f4374aSIngo Molnar 1012891c3970SOleg Nesterov return n; 1013a5f4374aSIngo Molnar } 1014a5f4374aSIngo Molnar 1015a5f4374aSIngo Molnar /* 1016891c3970SOleg Nesterov * For a given range in vma, build a list of probes that need to be inserted. 1017a5f4374aSIngo Molnar */ 1018891c3970SOleg Nesterov static void build_probe_list(struct inode *inode, 1019891c3970SOleg Nesterov struct vm_area_struct *vma, 1020891c3970SOleg Nesterov unsigned long start, unsigned long end, 1021891c3970SOleg Nesterov struct list_head *head) 1022a5f4374aSIngo Molnar { 1023891c3970SOleg Nesterov loff_t min, max; 1024891c3970SOleg Nesterov struct rb_node *n, *t; 1025891c3970SOleg Nesterov struct uprobe *u; 1026891c3970SOleg Nesterov 1027891c3970SOleg Nesterov INIT_LIST_HEAD(head); 1028cb113b47SOleg Nesterov min = vaddr_to_offset(vma, start); 1029891c3970SOleg Nesterov max = min + (end - start) - 1; 1030a5f4374aSIngo Molnar 10316f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 1032891c3970SOleg Nesterov n = find_node_in_range(inode, min, max); 1033891c3970SOleg Nesterov if (n) { 1034891c3970SOleg Nesterov for (t = n; t; t = rb_prev(t)) { 1035891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1036891c3970SOleg Nesterov if (u->inode != inode || u->offset < min) 1037a5f4374aSIngo Molnar break; 1038891c3970SOleg Nesterov list_add(&u->pending_list, head); 1039f231722aSOleg Nesterov get_uprobe(u); 1040a5f4374aSIngo Molnar } 1041891c3970SOleg Nesterov for (t = n; (t = rb_next(t)); ) { 1042891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1043891c3970SOleg Nesterov if (u->inode != inode || u->offset > max) 1044891c3970SOleg Nesterov break; 1045891c3970SOleg Nesterov list_add(&u->pending_list, head); 1046f231722aSOleg Nesterov get_uprobe(u); 1047891c3970SOleg Nesterov } 1048891c3970SOleg Nesterov } 10496f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 1050a5f4374aSIngo Molnar } 1051a5f4374aSIngo Molnar 1052a5f4374aSIngo Molnar /* 10535e5be71aSOleg Nesterov * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. 1054a5f4374aSIngo Molnar * 10555e5be71aSOleg Nesterov * Currently we ignore all errors and always return 0, the callers 10565e5be71aSOleg Nesterov * can't handle the failure anyway. 1057a5f4374aSIngo Molnar */ 1058a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1059a5f4374aSIngo Molnar { 1060a5f4374aSIngo Molnar struct list_head tmp_list; 1061665605a2SOleg Nesterov struct uprobe *uprobe, *u; 1062a5f4374aSIngo Molnar struct inode *inode; 1063a5f4374aSIngo Molnar 1064441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, true)) 1065a5f4374aSIngo Molnar return 0; 1066a5f4374aSIngo Molnar 1067f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 1068a5f4374aSIngo Molnar if (!inode) 1069a5f4374aSIngo Molnar return 0; 1070a5f4374aSIngo Molnar 1071a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1072891c3970SOleg Nesterov build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); 1073806a98bdSOleg Nesterov /* 1074806a98bdSOleg Nesterov * We can race with uprobe_unregister(), this uprobe can be already 1075806a98bdSOleg Nesterov * removed. But in this case filter_chain() must return false, all 1076806a98bdSOleg Nesterov * consumers have gone away. 1077806a98bdSOleg Nesterov */ 1078665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 1079806a98bdSOleg Nesterov if (!fatal_signal_pending(current) && 10808a7f2fa0SOleg Nesterov filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { 108157683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 10825e5be71aSOleg Nesterov install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1083a5f4374aSIngo Molnar } 1084a5f4374aSIngo Molnar put_uprobe(uprobe); 1085a5f4374aSIngo Molnar } 1086a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1087a5f4374aSIngo Molnar 10885e5be71aSOleg Nesterov return 0; 1089a5f4374aSIngo Molnar } 1090a5f4374aSIngo Molnar 10919f68f672SOleg Nesterov static bool 10929f68f672SOleg Nesterov vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) 10939f68f672SOleg Nesterov { 10949f68f672SOleg Nesterov loff_t min, max; 10959f68f672SOleg Nesterov struct inode *inode; 10969f68f672SOleg Nesterov struct rb_node *n; 10979f68f672SOleg Nesterov 1098f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 10999f68f672SOleg Nesterov 11009f68f672SOleg Nesterov min = vaddr_to_offset(vma, start); 11019f68f672SOleg Nesterov max = min + (end - start) - 1; 11029f68f672SOleg Nesterov 11039f68f672SOleg Nesterov spin_lock(&uprobes_treelock); 11049f68f672SOleg Nesterov n = find_node_in_range(inode, min, max); 11059f68f672SOleg Nesterov spin_unlock(&uprobes_treelock); 11069f68f672SOleg Nesterov 11079f68f672SOleg Nesterov return !!n; 11089f68f672SOleg Nesterov } 11099f68f672SOleg Nesterov 1110682968e0SSrikar Dronamraju /* 1111682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1112682968e0SSrikar Dronamraju */ 1113cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1114682968e0SSrikar Dronamraju { 1115441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, false)) 1116682968e0SSrikar Dronamraju return; 1117682968e0SSrikar Dronamraju 11182fd611a9SOleg Nesterov if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ 11192fd611a9SOleg Nesterov return; 11202fd611a9SOleg Nesterov 11219f68f672SOleg Nesterov if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || 11229f68f672SOleg Nesterov test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) 1123f8ac4ec9SOleg Nesterov return; 1124f8ac4ec9SOleg Nesterov 11259f68f672SOleg Nesterov if (vma_has_uprobes(vma, start, end)) 11269f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); 1127682968e0SSrikar Dronamraju } 1128682968e0SSrikar Dronamraju 1129d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 11306441ec8bSOleg Nesterov static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) 1131d4b3b638SSrikar Dronamraju { 1132704bde3cSOleg Nesterov struct vm_area_struct *vma; 1133704bde3cSOleg Nesterov int ret; 1134d4b3b638SSrikar Dronamraju 1135598fdc1dSMichal Hocko if (down_write_killable(&mm->mmap_sem)) 1136598fdc1dSMichal Hocko return -EINTR; 1137598fdc1dSMichal Hocko 1138704bde3cSOleg Nesterov if (mm->uprobes_state.xol_area) { 1139704bde3cSOleg Nesterov ret = -EALREADY; 1140d4b3b638SSrikar Dronamraju goto fail; 1141704bde3cSOleg Nesterov } 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 1153704bde3cSOleg Nesterov vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1154704bde3cSOleg Nesterov VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, 1155704bde3cSOleg Nesterov &area->xol_mapping); 1156704bde3cSOleg Nesterov if (IS_ERR(vma)) { 1157704bde3cSOleg Nesterov ret = PTR_ERR(vma); 1158d4b3b638SSrikar Dronamraju goto fail; 1159704bde3cSOleg Nesterov } 1160d4b3b638SSrikar Dronamraju 1161704bde3cSOleg Nesterov ret = 0; 1162d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1163d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1164d4b3b638SSrikar Dronamraju fail: 1165d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1166d4b3b638SSrikar Dronamraju 1167d4b3b638SSrikar Dronamraju return ret; 1168d4b3b638SSrikar Dronamraju } 1169d4b3b638SSrikar Dronamraju 1170af0d95afSOleg Nesterov static struct xol_area *__create_xol_area(unsigned long vaddr) 1171d4b3b638SSrikar Dronamraju { 11729b545df8SOleg Nesterov struct mm_struct *mm = current->mm; 1173e78aebfdSAnton Arapov uprobe_opcode_t insn = UPROBE_SWBP_INSN; 11746441ec8bSOleg Nesterov struct xol_area *area; 11759b545df8SOleg Nesterov 1176af0d95afSOleg Nesterov area = kmalloc(sizeof(*area), GFP_KERNEL); 1177d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1178c8a82538SOleg Nesterov goto out; 1179d4b3b638SSrikar Dronamraju 1180d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1181d4b3b638SSrikar Dronamraju if (!area->bitmap) 1182c8a82538SOleg Nesterov goto free_area; 1183c8a82538SOleg Nesterov 1184704bde3cSOleg Nesterov area->xol_mapping.name = "[uprobes]"; 1185869ae761SOleg Nesterov area->xol_mapping.fault = NULL; 1186704bde3cSOleg Nesterov area->xol_mapping.pages = area->pages; 1187f58bea2fSOleg Nesterov area->pages[0] = alloc_page(GFP_HIGHUSER); 1188f58bea2fSOleg Nesterov if (!area->pages[0]) 1189c8a82538SOleg Nesterov goto free_bitmap; 1190f58bea2fSOleg Nesterov area->pages[1] = NULL; 1191d4b3b638SSrikar Dronamraju 1192af0d95afSOleg Nesterov area->vaddr = vaddr; 1193d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 11946441ec8bSOleg Nesterov /* Reserve the 1st slot for get_trampoline_vaddr() */ 11956441ec8bSOleg Nesterov set_bit(0, area->bitmap); 11966441ec8bSOleg Nesterov atomic_set(&area->slot_count, 1); 1197297e765eSMarcin Nowakowski arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); 1198e78aebfdSAnton Arapov 11996441ec8bSOleg Nesterov if (!xol_add_vma(mm, area)) 1200d4b3b638SSrikar Dronamraju return area; 1201d4b3b638SSrikar Dronamraju 1202f58bea2fSOleg Nesterov __free_page(area->pages[0]); 1203c8a82538SOleg Nesterov free_bitmap: 1204d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1205c8a82538SOleg Nesterov free_area: 1206d4b3b638SSrikar Dronamraju kfree(area); 1207c8a82538SOleg Nesterov out: 12086441ec8bSOleg Nesterov return NULL; 12096441ec8bSOleg Nesterov } 12106441ec8bSOleg Nesterov 12116441ec8bSOleg Nesterov /* 12126441ec8bSOleg Nesterov * get_xol_area - Allocate process's xol_area if necessary. 12136441ec8bSOleg Nesterov * This area will be used for storing instructions for execution out of line. 12146441ec8bSOleg Nesterov * 12156441ec8bSOleg Nesterov * Returns the allocated area or NULL. 12166441ec8bSOleg Nesterov */ 12176441ec8bSOleg Nesterov static struct xol_area *get_xol_area(void) 12186441ec8bSOleg Nesterov { 12196441ec8bSOleg Nesterov struct mm_struct *mm = current->mm; 12206441ec8bSOleg Nesterov struct xol_area *area; 12216441ec8bSOleg Nesterov 12226441ec8bSOleg Nesterov if (!mm->uprobes_state.xol_area) 1223af0d95afSOleg Nesterov __create_xol_area(0); 12246441ec8bSOleg Nesterov 12259b545df8SOleg Nesterov area = mm->uprobes_state.xol_area; 12269b545df8SOleg Nesterov smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 12279b545df8SOleg Nesterov return area; 1228d4b3b638SSrikar Dronamraju } 1229d4b3b638SSrikar Dronamraju 1230d4b3b638SSrikar Dronamraju /* 1231d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1232d4b3b638SSrikar Dronamraju */ 1233d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1234d4b3b638SSrikar Dronamraju { 1235d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1236d4b3b638SSrikar Dronamraju 1237d4b3b638SSrikar Dronamraju if (!area) 1238d4b3b638SSrikar Dronamraju return; 1239d4b3b638SSrikar Dronamraju 1240f58bea2fSOleg Nesterov put_page(area->pages[0]); 1241d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1242d4b3b638SSrikar Dronamraju kfree(area); 1243d4b3b638SSrikar Dronamraju } 1244d4b3b638SSrikar Dronamraju 124532cdba1eSOleg Nesterov void uprobe_start_dup_mmap(void) 124632cdba1eSOleg Nesterov { 124732cdba1eSOleg Nesterov percpu_down_read(&dup_mmap_sem); 124832cdba1eSOleg Nesterov } 124932cdba1eSOleg Nesterov 125032cdba1eSOleg Nesterov void uprobe_end_dup_mmap(void) 125132cdba1eSOleg Nesterov { 125232cdba1eSOleg Nesterov percpu_up_read(&dup_mmap_sem); 125332cdba1eSOleg Nesterov } 125432cdba1eSOleg Nesterov 1255f8ac4ec9SOleg Nesterov void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) 1256f8ac4ec9SOleg Nesterov { 125761559a81SOleg Nesterov newmm->uprobes_state.xol_area = NULL; 125861559a81SOleg Nesterov 12599f68f672SOleg Nesterov if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { 1260f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &newmm->flags); 12619f68f672SOleg Nesterov /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ 12629f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &newmm->flags); 12639f68f672SOleg Nesterov } 1264f8ac4ec9SOleg Nesterov } 1265f8ac4ec9SOleg Nesterov 1266d4b3b638SSrikar Dronamraju /* 1267d4b3b638SSrikar Dronamraju * - search for a free slot. 1268d4b3b638SSrikar Dronamraju */ 1269d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1270d4b3b638SSrikar Dronamraju { 1271d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1272d4b3b638SSrikar Dronamraju int slot_nr; 1273d4b3b638SSrikar Dronamraju 1274d4b3b638SSrikar Dronamraju do { 1275d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1276d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1277d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1278d4b3b638SSrikar Dronamraju break; 1279d4b3b638SSrikar Dronamraju 1280d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1281d4b3b638SSrikar Dronamraju continue; 1282d4b3b638SSrikar Dronamraju } 1283d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1284d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1285d4b3b638SSrikar Dronamraju 1286d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1287d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1288d4b3b638SSrikar Dronamraju 1289d4b3b638SSrikar Dronamraju return slot_addr; 1290d4b3b638SSrikar Dronamraju } 1291d4b3b638SSrikar Dronamraju 1292d4b3b638SSrikar Dronamraju /* 1293a6cb3f6dSOleg Nesterov * xol_get_insn_slot - allocate a slot for xol. 1294d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1295d4b3b638SSrikar Dronamraju */ 1296a6cb3f6dSOleg Nesterov static unsigned long xol_get_insn_slot(struct uprobe *uprobe) 1297d4b3b638SSrikar Dronamraju { 1298d4b3b638SSrikar Dronamraju struct xol_area *area; 1299a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1300d4b3b638SSrikar Dronamraju 13019b545df8SOleg Nesterov area = get_xol_area(); 1302d4b3b638SSrikar Dronamraju if (!area) 1303d4b3b638SSrikar Dronamraju return 0; 1304d4b3b638SSrikar Dronamraju 1305a6cb3f6dSOleg Nesterov xol_vaddr = xol_take_insn_slot(area); 1306a6cb3f6dSOleg Nesterov if (unlikely(!xol_vaddr)) 1307d4b3b638SSrikar Dronamraju return 0; 1308d4b3b638SSrikar Dronamraju 1309f58bea2fSOleg Nesterov arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, 1310803200e2SOleg Nesterov &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); 1311d4b3b638SSrikar Dronamraju 1312a6cb3f6dSOleg Nesterov return xol_vaddr; 1313d4b3b638SSrikar Dronamraju } 1314d4b3b638SSrikar Dronamraju 1315d4b3b638SSrikar Dronamraju /* 1316d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1317d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1318d4b3b638SSrikar Dronamraju * subsequent requests. 1319d4b3b638SSrikar Dronamraju */ 1320d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1321d4b3b638SSrikar Dronamraju { 1322d4b3b638SSrikar Dronamraju struct xol_area *area; 1323d4b3b638SSrikar Dronamraju unsigned long vma_end; 1324d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1325d4b3b638SSrikar Dronamraju 1326d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1327d4b3b638SSrikar Dronamraju return; 1328d4b3b638SSrikar Dronamraju 1329d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1330af4355e9SOleg Nesterov if (unlikely(!slot_addr)) 1331d4b3b638SSrikar Dronamraju return; 1332d4b3b638SSrikar Dronamraju 1333d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1334d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1335d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1336d4b3b638SSrikar Dronamraju unsigned long offset; 1337d4b3b638SSrikar Dronamraju int slot_nr; 1338d4b3b638SSrikar Dronamraju 1339d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1340d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1341d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1342d4b3b638SSrikar Dronamraju return; 1343d4b3b638SSrikar Dronamraju 1344d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1345d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 13462a742cedSOleg Nesterov smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ 1347d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1348d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1349d4b3b638SSrikar Dronamraju 1350d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1351d4b3b638SSrikar Dronamraju } 1352d4b3b638SSrikar Dronamraju } 1353d4b3b638SSrikar Dronamraju 135472e6ae28SVictor Kamensky void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, 135572e6ae28SVictor Kamensky void *src, unsigned long len) 135672e6ae28SVictor Kamensky { 135772e6ae28SVictor Kamensky /* Initialize the slot */ 135872e6ae28SVictor Kamensky copy_to_page(page, vaddr, src, len); 135972e6ae28SVictor Kamensky 136072e6ae28SVictor Kamensky /* 136172e6ae28SVictor Kamensky * We probably need flush_icache_user_range() but it needs vma. 136272e6ae28SVictor Kamensky * This should work on most of architectures by default. If 136372e6ae28SVictor Kamensky * architecture needs to do something different it can define 136472e6ae28SVictor Kamensky * its own version of the function. 136572e6ae28SVictor Kamensky */ 136672e6ae28SVictor Kamensky flush_dcache_page(page); 136772e6ae28SVictor Kamensky } 136872e6ae28SVictor Kamensky 13690326f5a9SSrikar Dronamraju /** 13700326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 13710326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 13720326f5a9SSrikar Dronamraju * instruction. 13730326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 13740326f5a9SSrikar Dronamraju */ 13750326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 13760326f5a9SSrikar Dronamraju { 13770326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 13780326f5a9SSrikar Dronamraju } 13790326f5a9SSrikar Dronamraju 1380b02ef20aSOleg Nesterov unsigned long uprobe_get_trap_addr(struct pt_regs *regs) 1381b02ef20aSOleg Nesterov { 1382b02ef20aSOleg Nesterov struct uprobe_task *utask = current->utask; 1383b02ef20aSOleg Nesterov 1384b02ef20aSOleg Nesterov if (unlikely(utask && utask->active_uprobe)) 1385b02ef20aSOleg Nesterov return utask->vaddr; 1386b02ef20aSOleg Nesterov 1387b02ef20aSOleg Nesterov return instruction_pointer(regs); 1388b02ef20aSOleg Nesterov } 1389b02ef20aSOleg Nesterov 13902bb5e840SOleg Nesterov static struct return_instance *free_ret_instance(struct return_instance *ri) 13912bb5e840SOleg Nesterov { 13922bb5e840SOleg Nesterov struct return_instance *next = ri->next; 13932bb5e840SOleg Nesterov put_uprobe(ri->uprobe); 13942bb5e840SOleg Nesterov kfree(ri); 13952bb5e840SOleg Nesterov return next; 13962bb5e840SOleg Nesterov } 13972bb5e840SOleg Nesterov 13980326f5a9SSrikar Dronamraju /* 13990326f5a9SSrikar Dronamraju * Called with no locks held. 14000326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 14010326f5a9SSrikar Dronamraju */ 14020326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 14030326f5a9SSrikar Dronamraju { 14040326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 14052bb5e840SOleg Nesterov struct return_instance *ri; 14060326f5a9SSrikar Dronamraju 14070326f5a9SSrikar Dronamraju if (!utask) 14080326f5a9SSrikar Dronamraju return; 14090326f5a9SSrikar Dronamraju 14100326f5a9SSrikar Dronamraju if (utask->active_uprobe) 14110326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 14120326f5a9SSrikar Dronamraju 14130dfd0eb8SAnton Arapov ri = utask->return_instances; 14142bb5e840SOleg Nesterov while (ri) 14152bb5e840SOleg Nesterov ri = free_ret_instance(ri); 14160dfd0eb8SAnton Arapov 1417d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 14180326f5a9SSrikar Dronamraju kfree(utask); 14190326f5a9SSrikar Dronamraju t->utask = NULL; 14200326f5a9SSrikar Dronamraju } 14210326f5a9SSrikar Dronamraju 14220326f5a9SSrikar Dronamraju /* 14235a2df662SOleg Nesterov * Allocate a uprobe_task object for the task if if necessary. 14245a2df662SOleg Nesterov * Called when the thread hits a breakpoint. 14250326f5a9SSrikar Dronamraju * 14260326f5a9SSrikar Dronamraju * Returns: 14270326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 14280326f5a9SSrikar Dronamraju * - NULL otherwise 14290326f5a9SSrikar Dronamraju */ 14305a2df662SOleg Nesterov static struct uprobe_task *get_utask(void) 14310326f5a9SSrikar Dronamraju { 14325a2df662SOleg Nesterov if (!current->utask) 14335a2df662SOleg Nesterov current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 14345a2df662SOleg Nesterov return current->utask; 14350326f5a9SSrikar Dronamraju } 14360326f5a9SSrikar Dronamraju 1437248d3a7bSOleg Nesterov static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) 1438248d3a7bSOleg Nesterov { 1439248d3a7bSOleg Nesterov struct uprobe_task *n_utask; 1440248d3a7bSOleg Nesterov struct return_instance **p, *o, *n; 1441248d3a7bSOleg Nesterov 1442248d3a7bSOleg Nesterov n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 1443248d3a7bSOleg Nesterov if (!n_utask) 1444248d3a7bSOleg Nesterov return -ENOMEM; 1445248d3a7bSOleg Nesterov t->utask = n_utask; 1446248d3a7bSOleg Nesterov 1447248d3a7bSOleg Nesterov p = &n_utask->return_instances; 1448248d3a7bSOleg Nesterov for (o = o_utask->return_instances; o; o = o->next) { 1449248d3a7bSOleg Nesterov n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); 1450248d3a7bSOleg Nesterov if (!n) 1451248d3a7bSOleg Nesterov return -ENOMEM; 1452248d3a7bSOleg Nesterov 1453248d3a7bSOleg Nesterov *n = *o; 1454f231722aSOleg Nesterov get_uprobe(n->uprobe); 1455248d3a7bSOleg Nesterov n->next = NULL; 1456248d3a7bSOleg Nesterov 1457248d3a7bSOleg Nesterov *p = n; 1458248d3a7bSOleg Nesterov p = &n->next; 1459248d3a7bSOleg Nesterov n_utask->depth++; 1460248d3a7bSOleg Nesterov } 1461248d3a7bSOleg Nesterov 1462248d3a7bSOleg Nesterov return 0; 1463248d3a7bSOleg Nesterov } 1464248d3a7bSOleg Nesterov 1465248d3a7bSOleg Nesterov static void uprobe_warn(struct task_struct *t, const char *msg) 1466248d3a7bSOleg Nesterov { 1467248d3a7bSOleg Nesterov pr_warn("uprobe: %s:%d failed to %s\n", 1468248d3a7bSOleg Nesterov current->comm, current->pid, msg); 1469248d3a7bSOleg Nesterov } 1470248d3a7bSOleg Nesterov 1471aa59c53fSOleg Nesterov static void dup_xol_work(struct callback_head *work) 1472aa59c53fSOleg Nesterov { 1473aa59c53fSOleg Nesterov if (current->flags & PF_EXITING) 1474aa59c53fSOleg Nesterov return; 1475aa59c53fSOleg Nesterov 1476598fdc1dSMichal Hocko if (!__create_xol_area(current->utask->dup_xol_addr) && 1477598fdc1dSMichal Hocko !fatal_signal_pending(current)) 1478aa59c53fSOleg Nesterov uprobe_warn(current, "dup xol area"); 1479aa59c53fSOleg Nesterov } 1480aa59c53fSOleg Nesterov 1481e78aebfdSAnton Arapov /* 1482b68e0749SOleg Nesterov * Called in context of a new clone/fork from copy_process. 1483b68e0749SOleg Nesterov */ 14843ab67966SOleg Nesterov void uprobe_copy_process(struct task_struct *t, unsigned long flags) 1485b68e0749SOleg Nesterov { 1486248d3a7bSOleg Nesterov struct uprobe_task *utask = current->utask; 1487248d3a7bSOleg Nesterov struct mm_struct *mm = current->mm; 1488aa59c53fSOleg Nesterov struct xol_area *area; 1489248d3a7bSOleg Nesterov 1490b68e0749SOleg Nesterov t->utask = NULL; 1491248d3a7bSOleg Nesterov 14923ab67966SOleg Nesterov if (!utask || !utask->return_instances) 14933ab67966SOleg Nesterov return; 14943ab67966SOleg Nesterov 14953ab67966SOleg Nesterov if (mm == t->mm && !(flags & CLONE_VFORK)) 1496248d3a7bSOleg Nesterov return; 1497248d3a7bSOleg Nesterov 1498248d3a7bSOleg Nesterov if (dup_utask(t, utask)) 1499248d3a7bSOleg Nesterov return uprobe_warn(t, "dup ret instances"); 1500aa59c53fSOleg Nesterov 1501aa59c53fSOleg Nesterov /* The task can fork() after dup_xol_work() fails */ 1502aa59c53fSOleg Nesterov area = mm->uprobes_state.xol_area; 1503aa59c53fSOleg Nesterov if (!area) 1504aa59c53fSOleg Nesterov return uprobe_warn(t, "dup xol area"); 1505aa59c53fSOleg Nesterov 15063ab67966SOleg Nesterov if (mm == t->mm) 15073ab67966SOleg Nesterov return; 15083ab67966SOleg Nesterov 150932473431SOleg Nesterov t->utask->dup_xol_addr = area->vaddr; 151032473431SOleg Nesterov init_task_work(&t->utask->dup_xol_work, dup_xol_work); 151132473431SOleg Nesterov task_work_add(t, &t->utask->dup_xol_work, true); 1512b68e0749SOleg Nesterov } 1513b68e0749SOleg Nesterov 1514b68e0749SOleg Nesterov /* 1515e78aebfdSAnton Arapov * Current area->vaddr notion assume the trampoline address is always 1516e78aebfdSAnton Arapov * equal area->vaddr. 1517e78aebfdSAnton Arapov * 1518e78aebfdSAnton Arapov * Returns -1 in case the xol_area is not allocated. 1519e78aebfdSAnton Arapov */ 1520e78aebfdSAnton Arapov static unsigned long get_trampoline_vaddr(void) 1521e78aebfdSAnton Arapov { 1522e78aebfdSAnton Arapov struct xol_area *area; 1523e78aebfdSAnton Arapov unsigned long trampoline_vaddr = -1; 1524e78aebfdSAnton Arapov 1525e78aebfdSAnton Arapov area = current->mm->uprobes_state.xol_area; 1526e78aebfdSAnton Arapov smp_read_barrier_depends(); 1527e78aebfdSAnton Arapov if (area) 1528e78aebfdSAnton Arapov trampoline_vaddr = area->vaddr; 1529e78aebfdSAnton Arapov 1530e78aebfdSAnton Arapov return trampoline_vaddr; 1531e78aebfdSAnton Arapov } 1532e78aebfdSAnton Arapov 1533db087ef6SOleg Nesterov static void cleanup_return_instances(struct uprobe_task *utask, bool chained, 1534db087ef6SOleg Nesterov struct pt_regs *regs) 1535a5b7e1a8SOleg Nesterov { 1536a5b7e1a8SOleg Nesterov struct return_instance *ri = utask->return_instances; 1537db087ef6SOleg Nesterov enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL; 153886dcb702SOleg Nesterov 153986dcb702SOleg Nesterov while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) { 1540a5b7e1a8SOleg Nesterov ri = free_ret_instance(ri); 1541a5b7e1a8SOleg Nesterov utask->depth--; 1542a5b7e1a8SOleg Nesterov } 1543a5b7e1a8SOleg Nesterov utask->return_instances = ri; 1544a5b7e1a8SOleg Nesterov } 1545a5b7e1a8SOleg Nesterov 15460dfd0eb8SAnton Arapov static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) 15470dfd0eb8SAnton Arapov { 15480dfd0eb8SAnton Arapov struct return_instance *ri; 15490dfd0eb8SAnton Arapov struct uprobe_task *utask; 15500dfd0eb8SAnton Arapov unsigned long orig_ret_vaddr, trampoline_vaddr; 1551db087ef6SOleg Nesterov bool chained; 15520dfd0eb8SAnton Arapov 15530dfd0eb8SAnton Arapov if (!get_xol_area()) 15540dfd0eb8SAnton Arapov return; 15550dfd0eb8SAnton Arapov 15560dfd0eb8SAnton Arapov utask = get_utask(); 15570dfd0eb8SAnton Arapov if (!utask) 15580dfd0eb8SAnton Arapov return; 15590dfd0eb8SAnton Arapov 1560ded49c55SAnton Arapov if (utask->depth >= MAX_URETPROBE_DEPTH) { 1561ded49c55SAnton Arapov printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" 1562ded49c55SAnton Arapov " nestedness limit pid/tgid=%d/%d\n", 1563ded49c55SAnton Arapov current->pid, current->tgid); 1564ded49c55SAnton Arapov return; 1565ded49c55SAnton Arapov } 1566ded49c55SAnton Arapov 15676c58d0e4SOleg Nesterov ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); 15680dfd0eb8SAnton Arapov if (!ri) 15696c58d0e4SOleg Nesterov return; 15700dfd0eb8SAnton Arapov 15710dfd0eb8SAnton Arapov trampoline_vaddr = get_trampoline_vaddr(); 15720dfd0eb8SAnton Arapov orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); 15730dfd0eb8SAnton Arapov if (orig_ret_vaddr == -1) 15740dfd0eb8SAnton Arapov goto fail; 15750dfd0eb8SAnton Arapov 1576a5b7e1a8SOleg Nesterov /* drop the entries invalidated by longjmp() */ 1577db087ef6SOleg Nesterov chained = (orig_ret_vaddr == trampoline_vaddr); 1578db087ef6SOleg Nesterov cleanup_return_instances(utask, chained, regs); 1579a5b7e1a8SOleg Nesterov 15800dfd0eb8SAnton Arapov /* 15810dfd0eb8SAnton Arapov * We don't want to keep trampoline address in stack, rather keep the 15820dfd0eb8SAnton Arapov * original return address of first caller thru all the consequent 15830dfd0eb8SAnton Arapov * instances. This also makes breakpoint unwrapping easier. 15840dfd0eb8SAnton Arapov */ 1585db087ef6SOleg Nesterov if (chained) { 15860dfd0eb8SAnton Arapov if (!utask->return_instances) { 15870dfd0eb8SAnton Arapov /* 15880dfd0eb8SAnton Arapov * This situation is not possible. Likely we have an 15890dfd0eb8SAnton Arapov * attack from user-space. 15900dfd0eb8SAnton Arapov */ 15916c58d0e4SOleg Nesterov uprobe_warn(current, "handle tail call"); 15920dfd0eb8SAnton Arapov goto fail; 15930dfd0eb8SAnton Arapov } 15940dfd0eb8SAnton Arapov orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; 15950dfd0eb8SAnton Arapov } 15960dfd0eb8SAnton Arapov 1597f231722aSOleg Nesterov ri->uprobe = get_uprobe(uprobe); 15980dfd0eb8SAnton Arapov ri->func = instruction_pointer(regs); 15997b868e48SOleg Nesterov ri->stack = user_stack_pointer(regs); 16000dfd0eb8SAnton Arapov ri->orig_ret_vaddr = orig_ret_vaddr; 16010dfd0eb8SAnton Arapov ri->chained = chained; 16020dfd0eb8SAnton Arapov 1603ded49c55SAnton Arapov utask->depth++; 16040dfd0eb8SAnton Arapov ri->next = utask->return_instances; 16050dfd0eb8SAnton Arapov utask->return_instances = ri; 16060dfd0eb8SAnton Arapov 16070dfd0eb8SAnton Arapov return; 16080dfd0eb8SAnton Arapov fail: 16090dfd0eb8SAnton Arapov kfree(ri); 16100dfd0eb8SAnton Arapov } 16110dfd0eb8SAnton Arapov 16120326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 16130326f5a9SSrikar Dronamraju static int 1614a6cb3f6dSOleg Nesterov pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) 16150326f5a9SSrikar Dronamraju { 1616a6cb3f6dSOleg Nesterov struct uprobe_task *utask; 1617a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1618aba51024SOleg Nesterov int err; 1619d4b3b638SSrikar Dronamraju 1620608e7427SOleg Nesterov utask = get_utask(); 1621608e7427SOleg Nesterov if (!utask) 1622608e7427SOleg Nesterov return -ENOMEM; 1623a6cb3f6dSOleg Nesterov 1624a6cb3f6dSOleg Nesterov xol_vaddr = xol_get_insn_slot(uprobe); 1625a6cb3f6dSOleg Nesterov if (!xol_vaddr) 1626a6cb3f6dSOleg Nesterov return -ENOMEM; 1627a6cb3f6dSOleg Nesterov 1628a6cb3f6dSOleg Nesterov utask->xol_vaddr = xol_vaddr; 1629a6cb3f6dSOleg Nesterov utask->vaddr = bp_vaddr; 1630a6cb3f6dSOleg Nesterov 1631aba51024SOleg Nesterov err = arch_uprobe_pre_xol(&uprobe->arch, regs); 1632aba51024SOleg Nesterov if (unlikely(err)) { 1633aba51024SOleg Nesterov xol_free_insn_slot(current); 1634aba51024SOleg Nesterov return err; 1635aba51024SOleg Nesterov } 1636aba51024SOleg Nesterov 1637608e7427SOleg Nesterov utask->active_uprobe = uprobe; 1638608e7427SOleg Nesterov utask->state = UTASK_SSTEP; 1639aba51024SOleg Nesterov return 0; 16400326f5a9SSrikar Dronamraju } 16410326f5a9SSrikar Dronamraju 16420326f5a9SSrikar Dronamraju /* 16430326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 16440326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 16450326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 16460326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 16470326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 16480326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 16490326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 16500326f5a9SSrikar Dronamraju */ 16510326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 16520326f5a9SSrikar Dronamraju { 16530326f5a9SSrikar Dronamraju struct task_struct *t = current; 16540326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 16550326f5a9SSrikar Dronamraju 16560326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 16570326f5a9SSrikar Dronamraju return false; 16580326f5a9SSrikar Dronamraju 16590326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 16600326f5a9SSrikar Dronamraju 16610326f5a9SSrikar Dronamraju if (signal_pending(t)) { 16620326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 16630326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 16640326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 16650326f5a9SSrikar Dronamraju 16660326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 16670326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 16680326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 16690326f5a9SSrikar Dronamraju } 16700326f5a9SSrikar Dronamraju } 16710326f5a9SSrikar Dronamraju 16720326f5a9SSrikar Dronamraju return true; 16730326f5a9SSrikar Dronamraju } 16740326f5a9SSrikar Dronamraju 1675499a4f3eSOleg Nesterov static void mmf_recalc_uprobes(struct mm_struct *mm) 1676499a4f3eSOleg Nesterov { 1677499a4f3eSOleg Nesterov struct vm_area_struct *vma; 1678499a4f3eSOleg Nesterov 1679499a4f3eSOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 1680499a4f3eSOleg Nesterov if (!valid_vma(vma, false)) 1681499a4f3eSOleg Nesterov continue; 1682499a4f3eSOleg Nesterov /* 1683499a4f3eSOleg Nesterov * This is not strictly accurate, we can race with 1684499a4f3eSOleg Nesterov * uprobe_unregister() and see the already removed 1685499a4f3eSOleg Nesterov * uprobe if delete_uprobe() was not yet called. 168663633cbfSOleg Nesterov * Or this uprobe can be filtered out. 1687499a4f3eSOleg Nesterov */ 1688499a4f3eSOleg Nesterov if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) 1689499a4f3eSOleg Nesterov return; 1690499a4f3eSOleg Nesterov } 1691499a4f3eSOleg Nesterov 1692499a4f3eSOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 1693499a4f3eSOleg Nesterov } 1694499a4f3eSOleg Nesterov 16950908ad6eSAnanth N Mavinakayanahalli static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) 1696ec75fba9SOleg Nesterov { 1697ec75fba9SOleg Nesterov struct page *page; 1698ec75fba9SOleg Nesterov uprobe_opcode_t opcode; 1699ec75fba9SOleg Nesterov int result; 1700ec75fba9SOleg Nesterov 1701ec75fba9SOleg Nesterov pagefault_disable(); 1702bd28b145SLinus Torvalds result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr); 1703ec75fba9SOleg Nesterov pagefault_enable(); 1704ec75fba9SOleg Nesterov 1705ec75fba9SOleg Nesterov if (likely(result == 0)) 1706ec75fba9SOleg Nesterov goto out; 1707ec75fba9SOleg Nesterov 17081e987790SDave Hansen /* 17091e987790SDave Hansen * The NULL 'tsk' here ensures that any faults that occur here 17101e987790SDave Hansen * will not be accounted to the task. 'mm' *is* current->mm, 17111e987790SDave Hansen * but we treat this as a 'remote' access since it is 17121e987790SDave Hansen * essentially a kernel access to the memory. 17131e987790SDave Hansen */ 17149beae1eaSLorenzo Stoakes result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page, 17155b56d49fSLorenzo Stoakes NULL, NULL); 1716ec75fba9SOleg Nesterov if (result < 0) 1717ec75fba9SOleg Nesterov return result; 1718ec75fba9SOleg Nesterov 1719ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 1720ec75fba9SOleg Nesterov put_page(page); 1721ec75fba9SOleg Nesterov out: 17220908ad6eSAnanth N Mavinakayanahalli /* This needs to return true for any variant of the trap insn */ 17230908ad6eSAnanth N Mavinakayanahalli return is_trap_insn(&opcode); 1724ec75fba9SOleg Nesterov } 1725ec75fba9SOleg Nesterov 1726d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 17270326f5a9SSrikar Dronamraju { 17283a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 17293a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 17300326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 17310326f5a9SSrikar Dronamraju 17320326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 17330326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 17343a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 17353a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 1736f281769eSOleg Nesterov struct inode *inode = file_inode(vma->vm_file); 1737cb113b47SOleg Nesterov loff_t offset = vaddr_to_offset(vma, bp_vaddr); 17380326f5a9SSrikar Dronamraju 17390326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 17400326f5a9SSrikar Dronamraju } 1741d790d346SOleg Nesterov 1742d790d346SOleg Nesterov if (!uprobe) 17430908ad6eSAnanth N Mavinakayanahalli *is_swbp = is_trap_at_addr(mm, bp_vaddr); 1744d790d346SOleg Nesterov } else { 1745d790d346SOleg Nesterov *is_swbp = -EFAULT; 17463a9ea052SOleg Nesterov } 1747499a4f3eSOleg Nesterov 1748499a4f3eSOleg Nesterov if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) 1749499a4f3eSOleg Nesterov mmf_recalc_uprobes(mm); 17500326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 17510326f5a9SSrikar Dronamraju 17523a9ea052SOleg Nesterov return uprobe; 17533a9ea052SOleg Nesterov } 17543a9ea052SOleg Nesterov 1755da1816b1SOleg Nesterov static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 1756da1816b1SOleg Nesterov { 1757da1816b1SOleg Nesterov struct uprobe_consumer *uc; 1758da1816b1SOleg Nesterov int remove = UPROBE_HANDLER_REMOVE; 17590dfd0eb8SAnton Arapov bool need_prep = false; /* prepare return uprobe, when needed */ 1760da1816b1SOleg Nesterov 1761da1816b1SOleg Nesterov down_read(&uprobe->register_rwsem); 1762da1816b1SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 1763ea024870SAnton Arapov int rc = 0; 1764da1816b1SOleg Nesterov 1765ea024870SAnton Arapov if (uc->handler) { 1766ea024870SAnton Arapov rc = uc->handler(uc, regs); 1767da1816b1SOleg Nesterov WARN(rc & ~UPROBE_HANDLER_MASK, 1768da1816b1SOleg Nesterov "bad rc=0x%x from %pf()\n", rc, uc->handler); 1769ea024870SAnton Arapov } 17700dfd0eb8SAnton Arapov 17710dfd0eb8SAnton Arapov if (uc->ret_handler) 17720dfd0eb8SAnton Arapov need_prep = true; 17730dfd0eb8SAnton Arapov 1774da1816b1SOleg Nesterov remove &= rc; 1775da1816b1SOleg Nesterov } 1776da1816b1SOleg Nesterov 17770dfd0eb8SAnton Arapov if (need_prep && !remove) 17780dfd0eb8SAnton Arapov prepare_uretprobe(uprobe, regs); /* put bp at return */ 17790dfd0eb8SAnton Arapov 1780da1816b1SOleg Nesterov if (remove && uprobe->consumers) { 1781da1816b1SOleg Nesterov WARN_ON(!uprobe_is_active(uprobe)); 1782da1816b1SOleg Nesterov unapply_uprobe(uprobe, current->mm); 1783da1816b1SOleg Nesterov } 1784da1816b1SOleg Nesterov up_read(&uprobe->register_rwsem); 1785da1816b1SOleg Nesterov } 1786da1816b1SOleg Nesterov 1787fec8898dSAnton Arapov static void 1788fec8898dSAnton Arapov handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) 1789fec8898dSAnton Arapov { 1790fec8898dSAnton Arapov struct uprobe *uprobe = ri->uprobe; 1791fec8898dSAnton Arapov struct uprobe_consumer *uc; 1792fec8898dSAnton Arapov 1793fec8898dSAnton Arapov down_read(&uprobe->register_rwsem); 1794fec8898dSAnton Arapov for (uc = uprobe->consumers; uc; uc = uc->next) { 1795fec8898dSAnton Arapov if (uc->ret_handler) 1796fec8898dSAnton Arapov uc->ret_handler(uc, ri->func, regs); 1797fec8898dSAnton Arapov } 1798fec8898dSAnton Arapov up_read(&uprobe->register_rwsem); 1799fec8898dSAnton Arapov } 1800fec8898dSAnton Arapov 1801a83cfeb9SOleg Nesterov static struct return_instance *find_next_ret_chain(struct return_instance *ri) 1802a83cfeb9SOleg Nesterov { 1803a83cfeb9SOleg Nesterov bool chained; 1804a83cfeb9SOleg Nesterov 1805a83cfeb9SOleg Nesterov do { 1806a83cfeb9SOleg Nesterov chained = ri->chained; 1807a83cfeb9SOleg Nesterov ri = ri->next; /* can't be NULL if chained */ 1808a83cfeb9SOleg Nesterov } while (chained); 1809a83cfeb9SOleg Nesterov 1810a83cfeb9SOleg Nesterov return ri; 1811a83cfeb9SOleg Nesterov } 1812a83cfeb9SOleg Nesterov 18130b5256c7SOleg Nesterov static void handle_trampoline(struct pt_regs *regs) 1814fec8898dSAnton Arapov { 1815fec8898dSAnton Arapov struct uprobe_task *utask; 1816a83cfeb9SOleg Nesterov struct return_instance *ri, *next; 18175eeb50deSOleg Nesterov bool valid; 1818fec8898dSAnton Arapov 1819fec8898dSAnton Arapov utask = current->utask; 1820fec8898dSAnton Arapov if (!utask) 18210b5256c7SOleg Nesterov goto sigill; 1822fec8898dSAnton Arapov 1823fec8898dSAnton Arapov ri = utask->return_instances; 1824fec8898dSAnton Arapov if (!ri) 18250b5256c7SOleg Nesterov goto sigill; 1826fec8898dSAnton Arapov 18275eeb50deSOleg Nesterov do { 1828fec8898dSAnton Arapov /* 18295eeb50deSOleg Nesterov * We should throw out the frames invalidated by longjmp(). 18305eeb50deSOleg Nesterov * If this chain is valid, then the next one should be alive 18315eeb50deSOleg Nesterov * or NULL; the latter case means that nobody but ri->func 18325eeb50deSOleg Nesterov * could hit this trampoline on return. TODO: sigaltstack(). 1833fec8898dSAnton Arapov */ 18345eeb50deSOleg Nesterov next = find_next_ret_chain(ri); 183586dcb702SOleg Nesterov valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs); 18365eeb50deSOleg Nesterov 1837fec8898dSAnton Arapov instruction_pointer_set(regs, ri->orig_ret_vaddr); 1838a83cfeb9SOleg Nesterov do { 18395eeb50deSOleg Nesterov if (valid) 1840fec8898dSAnton Arapov handle_uretprobe_chain(ri, regs); 18412bb5e840SOleg Nesterov ri = free_ret_instance(ri); 1842878b5a6eSOleg Nesterov utask->depth--; 1843a83cfeb9SOleg Nesterov } while (ri != next); 18445eeb50deSOleg Nesterov } while (!valid); 1845fec8898dSAnton Arapov 1846fec8898dSAnton Arapov utask->return_instances = ri; 18470b5256c7SOleg Nesterov return; 1848fec8898dSAnton Arapov 18490b5256c7SOleg Nesterov sigill: 18500b5256c7SOleg Nesterov uprobe_warn(current, "handle uretprobe, sending SIGILL."); 18510b5256c7SOleg Nesterov force_sig_info(SIGILL, SEND_SIG_FORCED, current); 18520b5256c7SOleg Nesterov 1853fec8898dSAnton Arapov } 1854fec8898dSAnton Arapov 18556fe50a28SDavid A. Long bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) 18566fe50a28SDavid A. Long { 18576fe50a28SDavid A. Long return false; 18586fe50a28SDavid A. Long } 18596fe50a28SDavid A. Long 186086dcb702SOleg Nesterov bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, 186186dcb702SOleg Nesterov struct pt_regs *regs) 186297da8976SOleg Nesterov { 186397da8976SOleg Nesterov return true; 186497da8976SOleg Nesterov } 186597da8976SOleg Nesterov 18663a9ea052SOleg Nesterov /* 18673a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 18683a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 18693a9ea052SOleg Nesterov */ 18703a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 18713a9ea052SOleg Nesterov { 18723a9ea052SOleg Nesterov struct uprobe *uprobe; 18733a9ea052SOleg Nesterov unsigned long bp_vaddr; 187456bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 18753a9ea052SOleg Nesterov 18763a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 18770b5256c7SOleg Nesterov if (bp_vaddr == get_trampoline_vaddr()) 18780b5256c7SOleg Nesterov return handle_trampoline(regs); 1879fec8898dSAnton Arapov 1880fec8898dSAnton Arapov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 18810326f5a9SSrikar Dronamraju if (!uprobe) { 188256bb4cf6SOleg Nesterov if (is_swbp > 0) { 18830326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 18840326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 188556bb4cf6SOleg Nesterov } else { 188656bb4cf6SOleg Nesterov /* 188756bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 188856bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 188956bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 189056bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 189156bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 189256bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 189356bb4cf6SOleg Nesterov */ 189456bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 189556bb4cf6SOleg Nesterov } 18960326f5a9SSrikar Dronamraju return; 18970326f5a9SSrikar Dronamraju } 189874e59dfcSOleg Nesterov 189974e59dfcSOleg Nesterov /* change it in advance for ->handler() and restart */ 190074e59dfcSOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 190174e59dfcSOleg Nesterov 1902142b18ddSOleg Nesterov /* 1903142b18ddSOleg Nesterov * TODO: move copy_insn/etc into _register and remove this hack. 1904142b18ddSOleg Nesterov * After we hit the bp, _unregister + _register can install the 1905142b18ddSOleg Nesterov * new and not-yet-analyzed uprobe at the same address, restart. 1906142b18ddSOleg Nesterov */ 1907142b18ddSOleg Nesterov smp_rmb(); /* pairs with wmb() in install_breakpoint() */ 190871434f2fSOleg Nesterov if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) 190974e59dfcSOleg Nesterov goto out; 19100326f5a9SSrikar Dronamraju 191172fd293aSOleg Nesterov /* Tracing handlers use ->utask to communicate with fetch methods */ 191272fd293aSOleg Nesterov if (!get_utask()) 191372fd293aSOleg Nesterov goto out; 191472fd293aSOleg Nesterov 19156fe50a28SDavid A. Long if (arch_uprobe_ignore(&uprobe->arch, regs)) 19166fe50a28SDavid A. Long goto out; 19176fe50a28SDavid A. Long 19180326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 19196fe50a28SDavid A. Long 19208a6b1732SOleg Nesterov if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 19210578a970SOleg Nesterov goto out; 19220326f5a9SSrikar Dronamraju 1923608e7427SOleg Nesterov if (!pre_ssout(uprobe, regs, bp_vaddr)) 19240326f5a9SSrikar Dronamraju return; 19250326f5a9SSrikar Dronamraju 19268a6b1732SOleg Nesterov /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ 19270578a970SOleg Nesterov out: 19280326f5a9SSrikar Dronamraju put_uprobe(uprobe); 19290326f5a9SSrikar Dronamraju } 19300326f5a9SSrikar Dronamraju 19310326f5a9SSrikar Dronamraju /* 19320326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 19330326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 19340326f5a9SSrikar Dronamraju */ 19350326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 19360326f5a9SSrikar Dronamraju { 19370326f5a9SSrikar Dronamraju struct uprobe *uprobe; 1938014940baSOleg Nesterov int err = 0; 19390326f5a9SSrikar Dronamraju 19400326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 19410326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 1942014940baSOleg Nesterov err = arch_uprobe_post_xol(&uprobe->arch, regs); 19430326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 19440326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 19450326f5a9SSrikar Dronamraju else 19460326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 19470326f5a9SSrikar Dronamraju 19480326f5a9SSrikar Dronamraju put_uprobe(uprobe); 19490326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 19500326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 1951d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 19520326f5a9SSrikar Dronamraju 19530326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 19540326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 19550326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 1956014940baSOleg Nesterov 1957014940baSOleg Nesterov if (unlikely(err)) { 1958014940baSOleg Nesterov uprobe_warn(current, "execute the probed insn, sending SIGILL."); 1959014940baSOleg Nesterov force_sig_info(SIGILL, SEND_SIG_FORCED, current); 1960014940baSOleg Nesterov } 19610326f5a9SSrikar Dronamraju } 19620326f5a9SSrikar Dronamraju 19630326f5a9SSrikar Dronamraju /* 19641b08e907SOleg Nesterov * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and 19651b08e907SOleg Nesterov * allows the thread to return from interrupt. After that handle_swbp() 19661b08e907SOleg Nesterov * sets utask->active_uprobe. 19670326f5a9SSrikar Dronamraju * 19681b08e907SOleg Nesterov * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag 19691b08e907SOleg Nesterov * and allows the thread to return from interrupt. 19700326f5a9SSrikar Dronamraju * 19710326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 19720326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 19730326f5a9SSrikar Dronamraju */ 19740326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 19750326f5a9SSrikar Dronamraju { 19760326f5a9SSrikar Dronamraju struct uprobe_task *utask; 19770326f5a9SSrikar Dronamraju 1978db023ea5SOleg Nesterov clear_thread_flag(TIF_UPROBE); 1979db023ea5SOleg Nesterov 19800326f5a9SSrikar Dronamraju utask = current->utask; 19811b08e907SOleg Nesterov if (utask && utask->active_uprobe) 19820326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 19831b08e907SOleg Nesterov else 19841b08e907SOleg Nesterov handle_swbp(regs); 19850326f5a9SSrikar Dronamraju } 19860326f5a9SSrikar Dronamraju 19870326f5a9SSrikar Dronamraju /* 19880326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 19890326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 19900326f5a9SSrikar Dronamraju */ 19910326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 19920326f5a9SSrikar Dronamraju { 19930dfd0eb8SAnton Arapov if (!current->mm) 19940dfd0eb8SAnton Arapov return 0; 19950dfd0eb8SAnton Arapov 19960dfd0eb8SAnton Arapov if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && 19970dfd0eb8SAnton Arapov (!current->utask || !current->utask->return_instances)) 19980326f5a9SSrikar Dronamraju return 0; 19990326f5a9SSrikar Dronamraju 20000326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 20010326f5a9SSrikar Dronamraju return 1; 20020326f5a9SSrikar Dronamraju } 20030326f5a9SSrikar Dronamraju 20040326f5a9SSrikar Dronamraju /* 20050326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 20060326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 20070326f5a9SSrikar Dronamraju */ 20080326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 20090326f5a9SSrikar Dronamraju { 20100326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 20110326f5a9SSrikar Dronamraju 20120326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 20130326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 20140326f5a9SSrikar Dronamraju return 0; 20150326f5a9SSrikar Dronamraju 20160326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 20170326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 20180326f5a9SSrikar Dronamraju return 1; 20190326f5a9SSrikar Dronamraju } 20200326f5a9SSrikar Dronamraju 20210326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 20220326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 20230326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 20240326f5a9SSrikar Dronamraju }; 20250326f5a9SSrikar Dronamraju 2026a5f4374aSIngo Molnar static int __init init_uprobes(void) 2027a5f4374aSIngo Molnar { 2028a5f4374aSIngo Molnar int i; 2029a5f4374aSIngo Molnar 203066d06dffSOleg Nesterov for (i = 0; i < UPROBES_HASH_SZ; i++) 2031a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 20320326f5a9SSrikar Dronamraju 203332cdba1eSOleg Nesterov if (percpu_init_rwsem(&dup_mmap_sem)) 203432cdba1eSOleg Nesterov return -ENOMEM; 203532cdba1eSOleg Nesterov 20360326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 2037a5f4374aSIngo Molnar } 2038736e89d9SOleg Nesterov __initcall(init_uprobes); 2039