2 * User-space Probes (UProbes)
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
18 * Copyright (C) IBM Corporation, 2008-2012
22 * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
25 #include <linux/kernel.h>
26 #include <linux/highmem.h>
27 #include <linux/pagemap.h> /* read_mapping_page */
28 #include <linux/slab.h>
29 #include <linux/sched.h>
30 #include <linux/export.h>
31 #include <linux/rmap.h> /* anon_vma_prepare */
32 #include <linux/mmu_notifier.h> /* set_pte_at_notify */
33 #include <linux/swap.h> /* try_to_free_swap */
34 #include <linux/ptrace.h> /* user_enable_single_step */
35 #include <linux/kdebug.h> /* notifier mechanism */
36 #include "../../mm/internal.h" /* munlock_vma_page */
37 #include <linux/percpu-rwsem.h>
38 #include <linux/task_work.h>
40 #include <linux/uprobes.h>
42 #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES)
43 #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE
45 static struct rb_root uprobes_tree = RB_ROOT;
47 * allows us to skip the uprobe_mmap if there are no uprobe events active
48 * at this time. Probably a fine grained per inode count is better?
50 #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree)
52 static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */
54 #define UPROBES_HASH_SZ 13
55 /* serialize uprobe->pending_list */
56 static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];
57 #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ])
59 static struct percpu_rw_semaphore dup_mmap_sem;
61 /* Have a copy of original instruction */
62 #define UPROBE_COPY_INSN 0
65 struct rb_node rb_node; /* node in the rb tree */
67 struct rw_semaphore register_rwsem;
68 struct rw_semaphore consumer_rwsem;
69 struct list_head pending_list;
70 struct uprobe_consumer *consumers;
71 struct inode *inode; /* Also hold a ref to inode */
76 * The generic code assumes that it has two members of unknown type
77 * owned by the arch-specific code:
79 * insn - copy_insn() saves the original instruction here for
80 * arch_uprobe_analyze_insn().
82 * ixol - potentially modified instruction to execute out of
83 * line, copied to xol_area by xol_get_insn_slot().
85 struct arch_uprobe arch;
88 struct return_instance {
89 struct uprobe *uprobe;
91 unsigned long orig_ret_vaddr; /* original return address */
92 bool chained; /* true, if instance is nested */
94 struct return_instance *next; /* keep as stack */
98 * Execute out of line area: anonymous executable mapping installed
99 * by the probed task to execute the copy of the original instruction
100 * mangled by set_swbp().
102 * On a breakpoint hit, thread contests for a slot. It frees the
103 * slot after singlestep. Currently a fixed number of slots are
107 wait_queue_head_t wq; /* if all slots are busy */
108 atomic_t slot_count; /* number of in-use slots */
109 unsigned long *bitmap; /* 0 = free slot */
113 * We keep the vma's vm_start rather than a pointer to the vma
114 * itself. The probed process or a naughty kernel module could make
115 * the vma go away, and we must handle that reasonably gracefully.
117 unsigned long vaddr; /* Page(s) of instruction slots */
121 * valid_vma: Verify if the specified vma is an executable vma
122 * Relax restrictions while unregistering: vm_flags might have
123 * changed after breakpoint was inserted.
124 * - is_register: indicates if we are in register context.
125 * - Return 1 if the specified virtual address is in an
128 static bool valid_vma(struct vm_area_struct *vma, bool is_register)
130 vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE;
135 return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC;
138 static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
140 return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
143 static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr)
145 return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start);
149 * __replace_page - replace page in vma by new page.
150 * based on replace_page in mm/ksm.c
152 * @vma: vma that holds the pte pointing to page
153 * @addr: address the old @page is mapped at
154 * @page: the cowed page we are replacing by kpage
155 * @kpage: the modified page we replace page by
157 * Returns 0 on success, -EFAULT on failure.
159 static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
160 struct page *page, struct page *kpage)
162 struct mm_struct *mm = vma->vm_mm;
166 /* For mmu_notifiers */
167 const unsigned long mmun_start = addr;
168 const unsigned long mmun_end = addr + PAGE_SIZE;
170 /* For try_to_free_swap() and munlock_vma_page() below */
173 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
175 ptep = page_check_address(page, mm, addr, &ptl, 0);
180 page_add_new_anon_rmap(kpage, vma, addr);
182 if (!PageAnon(page)) {
183 dec_mm_counter(mm, MM_FILEPAGES);
184 inc_mm_counter(mm, MM_ANONPAGES);
187 flush_cache_page(vma, addr, pte_pfn(*ptep));
188 ptep_clear_flush(vma, addr, ptep);
189 set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
191 page_remove_rmap(page);
192 if (!page_mapped(page))
193 try_to_free_swap(page);
194 pte_unmap_unlock(ptep, ptl);
196 if (vma->vm_flags & VM_LOCKED)
197 munlock_vma_page(page);
202 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
208 * is_swbp_insn - check if instruction is breakpoint instruction.
209 * @insn: instruction to be checked.
210 * Default implementation of is_swbp_insn
211 * Returns true if @insn is a breakpoint instruction.
213 bool __weak is_swbp_insn(uprobe_opcode_t *insn)
215 return *insn == UPROBE_SWBP_INSN;
219 * is_trap_insn - check if instruction is breakpoint instruction.
220 * @insn: instruction to be checked.
221 * Default implementation of is_trap_insn
222 * Returns true if @insn is a breakpoint instruction.
224 * This function is needed for the case where an architecture has multiple
225 * trap instructions (like powerpc).
227 bool __weak is_trap_insn(uprobe_opcode_t *insn)
229 return is_swbp_insn(insn);
232 static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
234 void *kaddr = kmap_atomic(page);
235 memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
236 kunmap_atomic(kaddr);
239 static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len)
241 void *kaddr = kmap_atomic(page);
242 memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
243 kunmap_atomic(kaddr);
246 static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
248 uprobe_opcode_t old_opcode;
252 * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here.
253 * We do not check if it is any other 'trap variant' which could
254 * be conditional trap instruction such as the one powerpc supports.
256 * The logic is that we do not care if the underlying instruction
257 * is a trap variant; uprobes always wins over any other (gdb)
260 copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
261 is_swbp = is_swbp_insn(&old_opcode);
263 if (is_swbp_insn(new_opcode)) {
264 if (is_swbp) /* register: already installed? */
267 if (!is_swbp) /* unregister: was it changed by us? */
276 * Expect the breakpoint instruction to be the smallest size instruction for
277 * the architecture. If an arch has variable length instruction and the
278 * breakpoint instruction is not of the smallest length instruction
279 * supported by that architecture then we need to modify is_trap_at_addr and
280 * uprobe_write_opcode accordingly. This would never be a problem for archs
281 * that have fixed length instructions.
283 * uprobe_write_opcode - write the opcode at a given virtual address.
284 * @mm: the probed process address space.
285 * @vaddr: the virtual address to store the opcode.
286 * @opcode: opcode to be written at @vaddr.
288 * Called with mm->mmap_sem held for write.
289 * Return 0 (success) or a negative errno.
291 int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr,
292 uprobe_opcode_t opcode)
294 struct page *old_page, *new_page;
295 struct vm_area_struct *vma;
299 /* Read the page with vaddr into memory */
300 ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
304 ret = verify_opcode(old_page, vaddr, &opcode);
308 ret = anon_vma_prepare(vma);
313 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
317 if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))
320 __SetPageUptodate(new_page);
321 copy_highpage(new_page, old_page);
322 copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
324 ret = __replace_page(vma, vaddr, old_page, new_page);
326 mem_cgroup_uncharge_page(new_page);
329 page_cache_release(new_page);
333 if (unlikely(ret == -EAGAIN))
339 * set_swbp - store breakpoint at a given address.
340 * @auprobe: arch specific probepoint information.
341 * @mm: the probed process address space.
342 * @vaddr: the virtual address to insert the opcode.
344 * For mm @mm, store the breakpoint instruction at @vaddr.
345 * Return 0 (success) or a negative errno.
347 int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
349 return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
353 * set_orig_insn - Restore the original instruction.
354 * @mm: the probed process address space.
355 * @auprobe: arch specific probepoint information.
356 * @vaddr: the virtual address to insert the opcode.
358 * For mm @mm, restore the original opcode (opcode) at @vaddr.
359 * Return 0 (success) or a negative errno.
362 set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
364 return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn);
367 static int match_uprobe(struct uprobe *l, struct uprobe *r)
369 if (l->inode < r->inode)
372 if (l->inode > r->inode)
375 if (l->offset < r->offset)
378 if (l->offset > r->offset)
384 static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset)
386 struct uprobe u = { .inode = inode, .offset = offset };
387 struct rb_node *n = uprobes_tree.rb_node;
388 struct uprobe *uprobe;
392 uprobe = rb_entry(n, struct uprobe, rb_node);
393 match = match_uprobe(&u, uprobe);
395 atomic_inc(&uprobe->ref);
408 * Find a uprobe corresponding to a given inode:offset
409 * Acquires uprobes_treelock
411 static struct uprobe *find_uprobe(struct inode *inode, loff_t offset)
413 struct uprobe *uprobe;
415 spin_lock(&uprobes_treelock);
416 uprobe = __find_uprobe(inode, offset);
417 spin_unlock(&uprobes_treelock);
422 static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
424 struct rb_node **p = &uprobes_tree.rb_node;
425 struct rb_node *parent = NULL;
431 u = rb_entry(parent, struct uprobe, rb_node);
432 match = match_uprobe(uprobe, u);
439 p = &parent->rb_left;
441 p = &parent->rb_right;
446 rb_link_node(&uprobe->rb_node, parent, p);
447 rb_insert_color(&uprobe->rb_node, &uprobes_tree);
448 /* get access + creation ref */
449 atomic_set(&uprobe->ref, 2);
455 * Acquire uprobes_treelock.
456 * Matching uprobe already exists in rbtree;
457 * increment (access refcount) and return the matching uprobe.
459 * No matching uprobe; insert the uprobe in rb_tree;
460 * get a double refcount (access + creation) and return NULL.
462 static struct uprobe *insert_uprobe(struct uprobe *uprobe)
466 spin_lock(&uprobes_treelock);
467 u = __insert_uprobe(uprobe);
468 spin_unlock(&uprobes_treelock);
473 static void put_uprobe(struct uprobe *uprobe)
475 if (atomic_dec_and_test(&uprobe->ref))
479 static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
481 struct uprobe *uprobe, *cur_uprobe;
483 uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL);
487 uprobe->inode = igrab(inode);
488 uprobe->offset = offset;
489 init_rwsem(&uprobe->register_rwsem);
490 init_rwsem(&uprobe->consumer_rwsem);
492 /* add to uprobes_tree, sorted on inode:offset */
493 cur_uprobe = insert_uprobe(uprobe);
494 /* a uprobe exists for this inode:offset combination */
504 static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
506 down_write(&uprobe->consumer_rwsem);
507 uc->next = uprobe->consumers;
508 uprobe->consumers = uc;
509 up_write(&uprobe->consumer_rwsem);
513 * For uprobe @uprobe, delete the consumer @uc.
514 * Return true if the @uc is deleted successfully
517 static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc)
519 struct uprobe_consumer **con;
522 down_write(&uprobe->consumer_rwsem);
523 for (con = &uprobe->consumers; *con; con = &(*con)->next) {
530 up_write(&uprobe->consumer_rwsem);
535 static int __copy_insn(struct address_space *mapping, struct file *filp,
536 void *insn, int nbytes, loff_t offset)
540 if (!mapping->a_ops->readpage)
543 * Ensure that the page that has the original instruction is
544 * populated and in page-cache.
546 page = read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT, filp);
548 return PTR_ERR(page);
550 copy_from_page(page, offset, insn, nbytes);
551 page_cache_release(page);
556 static int copy_insn(struct uprobe *uprobe, struct file *filp)
558 struct address_space *mapping = uprobe->inode->i_mapping;
559 loff_t offs = uprobe->offset;
560 void *insn = &uprobe->arch.insn;
561 int size = sizeof(uprobe->arch.insn);
564 /* Copy only available bytes, -EIO if nothing was read */
566 if (offs >= i_size_read(uprobe->inode))
569 len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK));
570 err = __copy_insn(mapping, filp, insn, len, offs);
582 static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
583 struct mm_struct *mm, unsigned long vaddr)
587 if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
590 /* TODO: move this into _register, until then we abuse this sem. */
591 down_write(&uprobe->consumer_rwsem);
592 if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
595 ret = copy_insn(uprobe, file);
600 if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn))
603 ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr);
607 /* uprobe_write_opcode() assumes we don't cross page boundary */
608 BUG_ON((uprobe->offset & ~PAGE_MASK) +
609 UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
611 smp_wmb(); /* pairs with rmb() in find_active_uprobe() */
612 set_bit(UPROBE_COPY_INSN, &uprobe->flags);
615 up_write(&uprobe->consumer_rwsem);
620 static inline bool consumer_filter(struct uprobe_consumer *uc,
621 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
623 return !uc->filter || uc->filter(uc, ctx, mm);
626 static bool filter_chain(struct uprobe *uprobe,
627 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
629 struct uprobe_consumer *uc;
632 down_read(&uprobe->consumer_rwsem);
633 for (uc = uprobe->consumers; uc; uc = uc->next) {
634 ret = consumer_filter(uc, ctx, mm);
638 up_read(&uprobe->consumer_rwsem);
644 install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
645 struct vm_area_struct *vma, unsigned long vaddr)
650 ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr);
655 * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(),
656 * the task can hit this breakpoint right after __replace_page().
658 first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags);
660 set_bit(MMF_HAS_UPROBES, &mm->flags);
662 ret = set_swbp(&uprobe->arch, mm, vaddr);
664 clear_bit(MMF_RECALC_UPROBES, &mm->flags);
665 else if (first_uprobe)
666 clear_bit(MMF_HAS_UPROBES, &mm->flags);
672 remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
674 set_bit(MMF_RECALC_UPROBES, &mm->flags);
675 return set_orig_insn(&uprobe->arch, mm, vaddr);
678 static inline bool uprobe_is_active(struct uprobe *uprobe)
680 return !RB_EMPTY_NODE(&uprobe->rb_node);
683 * There could be threads that have already hit the breakpoint. They
684 * will recheck the current insn and restart if find_uprobe() fails.
685 * See find_active_uprobe().
687 static void delete_uprobe(struct uprobe *uprobe)
689 if (WARN_ON(!uprobe_is_active(uprobe)))
692 spin_lock(&uprobes_treelock);
693 rb_erase(&uprobe->rb_node, &uprobes_tree);
694 spin_unlock(&uprobes_treelock);
695 RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */
701 struct map_info *next;
702 struct mm_struct *mm;
706 static inline struct map_info *free_map_info(struct map_info *info)
708 struct map_info *next = info->next;
713 static struct map_info *
714 build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
716 unsigned long pgoff = offset >> PAGE_SHIFT;
717 struct vm_area_struct *vma;
718 struct map_info *curr = NULL;
719 struct map_info *prev = NULL;
720 struct map_info *info;
724 mutex_lock(&mapping->i_mmap_mutex);
725 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
726 if (!valid_vma(vma, is_register))
729 if (!prev && !more) {
731 * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through
732 * reclaim. This is optimistic, no harm done if it fails.
734 prev = kmalloc(sizeof(struct map_info),
735 GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN);
744 if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
752 info->mm = vma->vm_mm;
753 info->vaddr = offset_to_vaddr(vma, offset);
755 mutex_unlock(&mapping->i_mmap_mutex);
767 info = kmalloc(sizeof(struct map_info), GFP_KERNEL);
769 curr = ERR_PTR(-ENOMEM);
779 prev = free_map_info(prev);
784 register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new)
786 bool is_register = !!new;
787 struct map_info *info;
790 percpu_down_write(&dup_mmap_sem);
791 info = build_map_info(uprobe->inode->i_mapping,
792 uprobe->offset, is_register);
799 struct mm_struct *mm = info->mm;
800 struct vm_area_struct *vma;
802 if (err && is_register)
805 down_write(&mm->mmap_sem);
806 vma = find_vma(mm, info->vaddr);
807 if (!vma || !valid_vma(vma, is_register) ||
808 file_inode(vma->vm_file) != uprobe->inode)
811 if (vma->vm_start > info->vaddr ||
812 vaddr_to_offset(vma, info->vaddr) != uprobe->offset)
816 /* consult only the "caller", new consumer. */
817 if (consumer_filter(new,
818 UPROBE_FILTER_REGISTER, mm))
819 err = install_breakpoint(uprobe, mm, vma, info->vaddr);
820 } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) {
821 if (!filter_chain(uprobe,
822 UPROBE_FILTER_UNREGISTER, mm))
823 err |= remove_breakpoint(uprobe, mm, info->vaddr);
827 up_write(&mm->mmap_sem);
830 info = free_map_info(info);
833 percpu_up_write(&dup_mmap_sem);
837 static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
839 consumer_add(uprobe, uc);
840 return register_for_each_vma(uprobe, uc);
843 static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
847 if (!consumer_del(uprobe, uc)) /* WARN? */
850 err = register_for_each_vma(uprobe, NULL);
851 /* TODO : cant unregister? schedule a worker thread */
852 if (!uprobe->consumers && !err)
853 delete_uprobe(uprobe);
857 * uprobe_register - register a probe
858 * @inode: the file in which the probe has to be placed.
859 * @offset: offset from the start of the file.
860 * @uc: information on howto handle the probe..
862 * Apart from the access refcount, uprobe_register() takes a creation
863 * refcount (thro alloc_uprobe) if and only if this @uprobe is getting
864 * inserted into the rbtree (i.e first consumer for a @inode:@offset
865 * tuple). Creation refcount stops uprobe_unregister from freeing the
866 * @uprobe even before the register operation is complete. Creation
867 * refcount is released when the last @uc for the @uprobe
870 * Return errno if it cannot successully install probes
871 * else return 0 (success)
873 int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
875 struct uprobe *uprobe;
878 /* Uprobe must have at least one set consumer */
879 if (!uc->handler && !uc->ret_handler)
882 /* Racy, just to catch the obvious mistakes */
883 if (offset > i_size_read(inode))
887 uprobe = alloc_uprobe(inode, offset);
891 * We can race with uprobe_unregister()->delete_uprobe().
892 * Check uprobe_is_active() and retry if it is false.
894 down_write(&uprobe->register_rwsem);
896 if (likely(uprobe_is_active(uprobe))) {
897 ret = __uprobe_register(uprobe, uc);
899 __uprobe_unregister(uprobe, uc);
901 up_write(&uprobe->register_rwsem);
904 if (unlikely(ret == -EAGAIN))
908 EXPORT_SYMBOL_GPL(uprobe_register);
911 * uprobe_apply - unregister a already registered probe.
912 * @inode: the file in which the probe has to be removed.
913 * @offset: offset from the start of the file.
914 * @uc: consumer which wants to add more or remove some breakpoints
915 * @add: add or remove the breakpoints
917 int uprobe_apply(struct inode *inode, loff_t offset,
918 struct uprobe_consumer *uc, bool add)
920 struct uprobe *uprobe;
921 struct uprobe_consumer *con;
924 uprobe = find_uprobe(inode, offset);
928 down_write(&uprobe->register_rwsem);
929 for (con = uprobe->consumers; con && con != uc ; con = con->next)
932 ret = register_for_each_vma(uprobe, add ? uc : NULL);
933 up_write(&uprobe->register_rwsem);
940 * uprobe_unregister - unregister a already registered probe.
941 * @inode: the file in which the probe has to be removed.
942 * @offset: offset from the start of the file.
943 * @uc: identify which probe if multiple probes are colocated.
945 void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
947 struct uprobe *uprobe;
949 uprobe = find_uprobe(inode, offset);
953 down_write(&uprobe->register_rwsem);
954 __uprobe_unregister(uprobe, uc);
955 up_write(&uprobe->register_rwsem);
958 EXPORT_SYMBOL_GPL(uprobe_unregister);
960 static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
962 struct vm_area_struct *vma;
965 down_read(&mm->mmap_sem);
966 for (vma = mm->mmap; vma; vma = vma->vm_next) {
970 if (!valid_vma(vma, false) ||
971 file_inode(vma->vm_file) != uprobe->inode)
974 offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
975 if (uprobe->offset < offset ||
976 uprobe->offset >= offset + vma->vm_end - vma->vm_start)
979 vaddr = offset_to_vaddr(vma, uprobe->offset);
980 err |= remove_breakpoint(uprobe, mm, vaddr);
982 up_read(&mm->mmap_sem);
987 static struct rb_node *
988 find_node_in_range(struct inode *inode, loff_t min, loff_t max)
990 struct rb_node *n = uprobes_tree.rb_node;
993 struct uprobe *u = rb_entry(n, struct uprobe, rb_node);
995 if (inode < u->inode) {
997 } else if (inode > u->inode) {
1000 if (max < u->offset)
1002 else if (min > u->offset)
1013 * For a given range in vma, build a list of probes that need to be inserted.
1015 static void build_probe_list(struct inode *inode,
1016 struct vm_area_struct *vma,
1017 unsigned long start, unsigned long end,
1018 struct list_head *head)
1021 struct rb_node *n, *t;
1024 INIT_LIST_HEAD(head);
1025 min = vaddr_to_offset(vma, start);
1026 max = min + (end - start) - 1;
1028 spin_lock(&uprobes_treelock);
1029 n = find_node_in_range(inode, min, max);
1031 for (t = n; t; t = rb_prev(t)) {
1032 u = rb_entry(t, struct uprobe, rb_node);
1033 if (u->inode != inode || u->offset < min)
1035 list_add(&u->pending_list, head);
1036 atomic_inc(&u->ref);
1038 for (t = n; (t = rb_next(t)); ) {
1039 u = rb_entry(t, struct uprobe, rb_node);
1040 if (u->inode != inode || u->offset > max)
1042 list_add(&u->pending_list, head);
1043 atomic_inc(&u->ref);
1046 spin_unlock(&uprobes_treelock);
1050 * Called from mmap_region/vma_adjust with mm->mmap_sem acquired.
1052 * Currently we ignore all errors and always return 0, the callers
1053 * can't handle the failure anyway.
1055 int uprobe_mmap(struct vm_area_struct *vma)
1057 struct list_head tmp_list;
1058 struct uprobe *uprobe, *u;
1059 struct inode *inode;
1061 if (no_uprobe_events() || !valid_vma(vma, true))
1064 inode = file_inode(vma->vm_file);
1068 mutex_lock(uprobes_mmap_hash(inode));
1069 build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);
1071 * We can race with uprobe_unregister(), this uprobe can be already
1072 * removed. But in this case filter_chain() must return false, all
1073 * consumers have gone away.
1075 list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
1076 if (!fatal_signal_pending(current) &&
1077 filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) {
1078 unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
1079 install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
1083 mutex_unlock(uprobes_mmap_hash(inode));
1089 vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end)
1092 struct inode *inode;
1095 inode = file_inode(vma->vm_file);
1097 min = vaddr_to_offset(vma, start);
1098 max = min + (end - start) - 1;
1100 spin_lock(&uprobes_treelock);
1101 n = find_node_in_range(inode, min, max);
1102 spin_unlock(&uprobes_treelock);
1108 * Called in context of a munmap of a vma.
1110 void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
1112 if (no_uprobe_events() || !valid_vma(vma, false))
1115 if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
1118 if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) ||
1119 test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags))
1122 if (vma_has_uprobes(vma, start, end))
1123 set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
1126 /* Slot allocation for XOL */
1127 static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
1129 int ret = -EALREADY;
1131 down_write(&mm->mmap_sem);
1132 if (mm->uprobes_state.xol_area)
1136 /* Try to map as high as possible, this is only a hint. */
1137 area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE,
1139 if (area->vaddr & ~PAGE_MASK) {
1145 ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE,
1146 VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page);
1150 smp_wmb(); /* pairs with get_xol_area() */
1151 mm->uprobes_state.xol_area = area;
1153 up_write(&mm->mmap_sem);
1158 static struct xol_area *__create_xol_area(unsigned long vaddr)
1160 struct mm_struct *mm = current->mm;
1161 uprobe_opcode_t insn = UPROBE_SWBP_INSN;
1162 struct xol_area *area;
1164 area = kmalloc(sizeof(*area), GFP_KERNEL);
1165 if (unlikely(!area))
1168 area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL);
1172 area->page = alloc_page(GFP_HIGHUSER);
1176 area->vaddr = vaddr;
1177 init_waitqueue_head(&area->wq);
1178 /* Reserve the 1st slot for get_trampoline_vaddr() */
1179 set_bit(0, area->bitmap);
1180 atomic_set(&area->slot_count, 1);
1181 copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE);
1183 if (!xol_add_vma(mm, area))
1186 __free_page(area->page);
1188 kfree(area->bitmap);
1196 * get_xol_area - Allocate process's xol_area if necessary.
1197 * This area will be used for storing instructions for execution out of line.
1199 * Returns the allocated area or NULL.
1201 static struct xol_area *get_xol_area(void)
1203 struct mm_struct *mm = current->mm;
1204 struct xol_area *area;
1206 if (!mm->uprobes_state.xol_area)
1207 __create_xol_area(0);
1209 area = mm->uprobes_state.xol_area;
1210 smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
1215 * uprobe_clear_state - Free the area allocated for slots.
1217 void uprobe_clear_state(struct mm_struct *mm)
1219 struct xol_area *area = mm->uprobes_state.xol_area;
1224 put_page(area->page);
1225 kfree(area->bitmap);
1229 void uprobe_start_dup_mmap(void)
1231 percpu_down_read(&dup_mmap_sem);
1234 void uprobe_end_dup_mmap(void)
1236 percpu_up_read(&dup_mmap_sem);
1239 void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
1241 newmm->uprobes_state.xol_area = NULL;
1243 if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) {
1244 set_bit(MMF_HAS_UPROBES, &newmm->flags);
1245 /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */
1246 set_bit(MMF_RECALC_UPROBES, &newmm->flags);
1251 * - search for a free slot.
1253 static unsigned long xol_take_insn_slot(struct xol_area *area)
1255 unsigned long slot_addr;
1259 slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE);
1260 if (slot_nr < UINSNS_PER_PAGE) {
1261 if (!test_and_set_bit(slot_nr, area->bitmap))
1264 slot_nr = UINSNS_PER_PAGE;
1267 wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE));
1268 } while (slot_nr >= UINSNS_PER_PAGE);
1270 slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES);
1271 atomic_inc(&area->slot_count);
1277 * xol_get_insn_slot - allocate a slot for xol.
1278 * Returns the allocated slot address or 0.
1280 static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
1282 struct xol_area *area;
1283 unsigned long xol_vaddr;
1285 area = get_xol_area();
1289 xol_vaddr = xol_take_insn_slot(area);
1290 if (unlikely(!xol_vaddr))
1293 /* Initialize the slot */
1294 copy_to_page(area->page, xol_vaddr,
1295 &uprobe->arch.ixol, sizeof(uprobe->arch.ixol));
1297 * We probably need flush_icache_user_range() but it needs vma.
1298 * This should work on supported architectures too.
1300 flush_dcache_page(area->page);
1306 * xol_free_insn_slot - If slot was earlier allocated by
1307 * @xol_get_insn_slot(), make the slot available for
1308 * subsequent requests.
1310 static void xol_free_insn_slot(struct task_struct *tsk)
1312 struct xol_area *area;
1313 unsigned long vma_end;
1314 unsigned long slot_addr;
1316 if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask)
1319 slot_addr = tsk->utask->xol_vaddr;
1320 if (unlikely(!slot_addr))
1323 area = tsk->mm->uprobes_state.xol_area;
1324 vma_end = area->vaddr + PAGE_SIZE;
1325 if (area->vaddr <= slot_addr && slot_addr < vma_end) {
1326 unsigned long offset;
1329 offset = slot_addr - area->vaddr;
1330 slot_nr = offset / UPROBE_XOL_SLOT_BYTES;
1331 if (slot_nr >= UINSNS_PER_PAGE)
1334 clear_bit(slot_nr, area->bitmap);
1335 atomic_dec(&area->slot_count);
1336 if (waitqueue_active(&area->wq))
1339 tsk->utask->xol_vaddr = 0;
1344 * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
1345 * @regs: Reflects the saved state of the task after it has hit a breakpoint
1347 * Return the address of the breakpoint instruction.
1349 unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs)
1351 return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE;
1354 unsigned long uprobe_get_trap_addr(struct pt_regs *regs)
1356 struct uprobe_task *utask = current->utask;
1358 if (unlikely(utask && utask->active_uprobe))
1359 return utask->vaddr;
1361 return instruction_pointer(regs);
1365 * Called with no locks held.
1366 * Called in context of a exiting or a exec-ing thread.
1368 void uprobe_free_utask(struct task_struct *t)
1370 struct uprobe_task *utask = t->utask;
1371 struct return_instance *ri, *tmp;
1376 if (utask->active_uprobe)
1377 put_uprobe(utask->active_uprobe);
1379 ri = utask->return_instances;
1384 put_uprobe(tmp->uprobe);
1388 xol_free_insn_slot(t);
1394 * Allocate a uprobe_task object for the task if if necessary.
1395 * Called when the thread hits a breakpoint.
1398 * - pointer to new uprobe_task on success
1401 static struct uprobe_task *get_utask(void)
1403 if (!current->utask)
1404 current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
1405 return current->utask;
1408 static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)
1410 struct uprobe_task *n_utask;
1411 struct return_instance **p, *o, *n;
1413 n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
1418 p = &n_utask->return_instances;
1419 for (o = o_utask->return_instances; o; o = o->next) {
1420 n = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
1425 atomic_inc(&n->uprobe->ref);
1436 static void uprobe_warn(struct task_struct *t, const char *msg)
1438 pr_warn("uprobe: %s:%d failed to %s\n",
1439 current->comm, current->pid, msg);
1442 static void dup_xol_work(struct callback_head *work)
1444 if (current->flags & PF_EXITING)
1447 if (!__create_xol_area(current->utask->dup_xol_addr))
1448 uprobe_warn(current, "dup xol area");
1452 * Called in context of a new clone/fork from copy_process.
1454 void uprobe_copy_process(struct task_struct *t, unsigned long flags)
1456 struct uprobe_task *utask = current->utask;
1457 struct mm_struct *mm = current->mm;
1458 struct xol_area *area;
1462 if (!utask || !utask->return_instances)
1465 if (mm == t->mm && !(flags & CLONE_VFORK))
1468 if (dup_utask(t, utask))
1469 return uprobe_warn(t, "dup ret instances");
1471 /* The task can fork() after dup_xol_work() fails */
1472 area = mm->uprobes_state.xol_area;
1474 return uprobe_warn(t, "dup xol area");
1479 t->utask->dup_xol_addr = area->vaddr;
1480 init_task_work(&t->utask->dup_xol_work, dup_xol_work);
1481 task_work_add(t, &t->utask->dup_xol_work, true);
1485 * Current area->vaddr notion assume the trampoline address is always
1486 * equal area->vaddr.
1488 * Returns -1 in case the xol_area is not allocated.
1490 static unsigned long get_trampoline_vaddr(void)
1492 struct xol_area *area;
1493 unsigned long trampoline_vaddr = -1;
1495 area = current->mm->uprobes_state.xol_area;
1496 smp_read_barrier_depends();
1498 trampoline_vaddr = area->vaddr;
1500 return trampoline_vaddr;
1503 static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
1505 struct return_instance *ri;
1506 struct uprobe_task *utask;
1507 unsigned long orig_ret_vaddr, trampoline_vaddr;
1508 bool chained = false;
1510 if (!get_xol_area())
1513 utask = get_utask();
1517 if (utask->depth >= MAX_URETPROBE_DEPTH) {
1518 printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to"
1519 " nestedness limit pid/tgid=%d/%d\n",
1520 current->pid, current->tgid);
1524 ri = kzalloc(sizeof(struct return_instance), GFP_KERNEL);
1528 trampoline_vaddr = get_trampoline_vaddr();
1529 orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs);
1530 if (orig_ret_vaddr == -1)
1534 * We don't want to keep trampoline address in stack, rather keep the
1535 * original return address of first caller thru all the consequent
1536 * instances. This also makes breakpoint unwrapping easier.
1538 if (orig_ret_vaddr == trampoline_vaddr) {
1539 if (!utask->return_instances) {
1541 * This situation is not possible. Likely we have an
1542 * attack from user-space.
1544 pr_warn("uprobe: unable to set uretprobe pid/tgid=%d/%d\n",
1545 current->pid, current->tgid);
1550 orig_ret_vaddr = utask->return_instances->orig_ret_vaddr;
1553 atomic_inc(&uprobe->ref);
1554 ri->uprobe = uprobe;
1555 ri->func = instruction_pointer(regs);
1556 ri->orig_ret_vaddr = orig_ret_vaddr;
1557 ri->chained = chained;
1561 /* add instance to the stack */
1562 ri->next = utask->return_instances;
1563 utask->return_instances = ri;
1571 /* Prepare to single-step probed instruction out of line. */
1573 pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
1575 struct uprobe_task *utask;
1576 unsigned long xol_vaddr;
1579 utask = get_utask();
1583 xol_vaddr = xol_get_insn_slot(uprobe);
1587 utask->xol_vaddr = xol_vaddr;
1588 utask->vaddr = bp_vaddr;
1590 err = arch_uprobe_pre_xol(&uprobe->arch, regs);
1591 if (unlikely(err)) {
1592 xol_free_insn_slot(current);
1596 utask->active_uprobe = uprobe;
1597 utask->state = UTASK_SSTEP;
1602 * If we are singlestepping, then ensure this thread is not connected to
1603 * non-fatal signals until completion of singlestep. When xol insn itself
1604 * triggers the signal, restart the original insn even if the task is
1605 * already SIGKILL'ed (since coredump should report the correct ip). This
1606 * is even more important if the task has a handler for SIGSEGV/etc, The
1607 * _same_ instruction should be repeated again after return from the signal
1608 * handler, and SSTEP can never finish in this case.
1610 bool uprobe_deny_signal(void)
1612 struct task_struct *t = current;
1613 struct uprobe_task *utask = t->utask;
1615 if (likely(!utask || !utask->active_uprobe))
1618 WARN_ON_ONCE(utask->state != UTASK_SSTEP);
1620 if (signal_pending(t)) {
1621 spin_lock_irq(&t->sighand->siglock);
1622 clear_tsk_thread_flag(t, TIF_SIGPENDING);
1623 spin_unlock_irq(&t->sighand->siglock);
1625 if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) {
1626 utask->state = UTASK_SSTEP_TRAPPED;
1627 set_tsk_thread_flag(t, TIF_UPROBE);
1628 set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
1635 static void mmf_recalc_uprobes(struct mm_struct *mm)
1637 struct vm_area_struct *vma;
1639 for (vma = mm->mmap; vma; vma = vma->vm_next) {
1640 if (!valid_vma(vma, false))
1643 * This is not strictly accurate, we can race with
1644 * uprobe_unregister() and see the already removed
1645 * uprobe if delete_uprobe() was not yet called.
1646 * Or this uprobe can be filtered out.
1648 if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end))
1652 clear_bit(MMF_HAS_UPROBES, &mm->flags);
1655 static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
1658 uprobe_opcode_t opcode;
1661 pagefault_disable();
1662 result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
1666 if (likely(result == 0))
1669 result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
1673 copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
1676 /* This needs to return true for any variant of the trap insn */
1677 return is_trap_insn(&opcode);
1680 static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
1682 struct mm_struct *mm = current->mm;
1683 struct uprobe *uprobe = NULL;
1684 struct vm_area_struct *vma;
1686 down_read(&mm->mmap_sem);
1687 vma = find_vma(mm, bp_vaddr);
1688 if (vma && vma->vm_start <= bp_vaddr) {
1689 if (valid_vma(vma, false)) {
1690 struct inode *inode = file_inode(vma->vm_file);
1691 loff_t offset = vaddr_to_offset(vma, bp_vaddr);
1693 uprobe = find_uprobe(inode, offset);
1697 *is_swbp = is_trap_at_addr(mm, bp_vaddr);
1702 if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags))
1703 mmf_recalc_uprobes(mm);
1704 up_read(&mm->mmap_sem);
1709 static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
1711 struct uprobe_consumer *uc;
1712 int remove = UPROBE_HANDLER_REMOVE;
1713 bool need_prep = false; /* prepare return uprobe, when needed */
1715 down_read(&uprobe->register_rwsem);
1716 for (uc = uprobe->consumers; uc; uc = uc->next) {
1720 rc = uc->handler(uc, regs);
1721 WARN(rc & ~UPROBE_HANDLER_MASK,
1722 "bad rc=0x%x from %pf()\n", rc, uc->handler);
1725 if (uc->ret_handler)
1731 if (need_prep && !remove)
1732 prepare_uretprobe(uprobe, regs); /* put bp at return */
1734 if (remove && uprobe->consumers) {
1735 WARN_ON(!uprobe_is_active(uprobe));
1736 unapply_uprobe(uprobe, current->mm);
1738 up_read(&uprobe->register_rwsem);
1742 handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs)
1744 struct uprobe *uprobe = ri->uprobe;
1745 struct uprobe_consumer *uc;
1747 down_read(&uprobe->register_rwsem);
1748 for (uc = uprobe->consumers; uc; uc = uc->next) {
1749 if (uc->ret_handler)
1750 uc->ret_handler(uc, ri->func, regs);
1752 up_read(&uprobe->register_rwsem);
1755 static bool handle_trampoline(struct pt_regs *regs)
1757 struct uprobe_task *utask;
1758 struct return_instance *ri, *tmp;
1761 utask = current->utask;
1765 ri = utask->return_instances;
1770 * TODO: we should throw out return_instance's invalidated by
1771 * longjmp(), currently we assume that the probed function always
1774 instruction_pointer_set(regs, ri->orig_ret_vaddr);
1777 handle_uretprobe_chain(ri, regs);
1779 chained = ri->chained;
1780 put_uprobe(ri->uprobe);
1792 utask->return_instances = ri;
1797 bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs)
1803 * Run handler and ask thread to singlestep.
1804 * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
1806 static void handle_swbp(struct pt_regs *regs)
1808 struct uprobe *uprobe;
1809 unsigned long bp_vaddr;
1810 int uninitialized_var(is_swbp);
1812 bp_vaddr = uprobe_get_swbp_addr(regs);
1813 if (bp_vaddr == get_trampoline_vaddr()) {
1814 if (handle_trampoline(regs))
1817 pr_warn("uprobe: unable to handle uretprobe pid/tgid=%d/%d\n",
1818 current->pid, current->tgid);
1821 uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
1824 /* No matching uprobe; signal SIGTRAP. */
1825 send_sig(SIGTRAP, current, 0);
1828 * Either we raced with uprobe_unregister() or we can't
1829 * access this memory. The latter is only possible if
1830 * another thread plays with our ->mm. In both cases
1831 * we can simply restart. If this vma was unmapped we
1832 * can pretend this insn was not executed yet and get
1833 * the (correct) SIGSEGV after restart.
1835 instruction_pointer_set(regs, bp_vaddr);
1840 /* change it in advance for ->handler() and restart */
1841 instruction_pointer_set(regs, bp_vaddr);
1844 * TODO: move copy_insn/etc into _register and remove this hack.
1845 * After we hit the bp, _unregister + _register can install the
1846 * new and not-yet-analyzed uprobe at the same address, restart.
1848 smp_rmb(); /* pairs with wmb() in install_breakpoint() */
1849 if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
1852 /* Tracing handlers use ->utask to communicate with fetch methods */
1856 if (arch_uprobe_ignore(&uprobe->arch, regs))
1859 handler_chain(uprobe, regs);
1861 if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
1864 if (!pre_ssout(uprobe, regs, bp_vaddr))
1867 /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */
1873 * Perform required fix-ups and disable singlestep.
1874 * Allow pending signals to take effect.
1876 static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
1878 struct uprobe *uprobe;
1881 uprobe = utask->active_uprobe;
1882 if (utask->state == UTASK_SSTEP_ACK)
1883 err = arch_uprobe_post_xol(&uprobe->arch, regs);
1884 else if (utask->state == UTASK_SSTEP_TRAPPED)
1885 arch_uprobe_abort_xol(&uprobe->arch, regs);
1890 utask->active_uprobe = NULL;
1891 utask->state = UTASK_RUNNING;
1892 xol_free_insn_slot(current);
1894 spin_lock_irq(¤t->sighand->siglock);
1895 recalc_sigpending(); /* see uprobe_deny_signal() */
1896 spin_unlock_irq(¤t->sighand->siglock);
1898 if (unlikely(err)) {
1899 uprobe_warn(current, "execute the probed insn, sending SIGILL.");
1900 force_sig_info(SIGILL, SEND_SIG_FORCED, current);
1905 * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and
1906 * allows the thread to return from interrupt. After that handle_swbp()
1907 * sets utask->active_uprobe.
1909 * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag
1910 * and allows the thread to return from interrupt.
1912 * While returning to userspace, thread notices the TIF_UPROBE flag and calls
1913 * uprobe_notify_resume().
1915 void uprobe_notify_resume(struct pt_regs *regs)
1917 struct uprobe_task *utask;
1919 clear_thread_flag(TIF_UPROBE);
1921 utask = current->utask;
1922 if (utask && utask->active_uprobe)
1923 handle_singlestep(utask, regs);
1929 * uprobe_pre_sstep_notifier gets called from interrupt context as part of
1930 * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit.
1932 int uprobe_pre_sstep_notifier(struct pt_regs *regs)
1937 if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) &&
1938 (!current->utask || !current->utask->return_instances))
1941 set_thread_flag(TIF_UPROBE);
1946 * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier
1947 * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep.
1949 int uprobe_post_sstep_notifier(struct pt_regs *regs)
1951 struct uprobe_task *utask = current->utask;
1953 if (!current->mm || !utask || !utask->active_uprobe)
1954 /* task is currently not uprobed */
1957 utask->state = UTASK_SSTEP_ACK;
1958 set_thread_flag(TIF_UPROBE);
1962 static struct notifier_block uprobe_exception_nb = {
1963 .notifier_call = arch_uprobe_exception_notify,
1964 .priority = INT_MAX-1, /* notified after kprobes, kgdb */
1967 static int __init init_uprobes(void)
1971 for (i = 0; i < UPROBES_HASH_SZ; i++)
1972 mutex_init(&uprobes_mmap_mutex[i]);
1974 if (percpu_init_rwsem(&dup_mmap_sem))
1977 return register_die_notifier(&uprobe_exception_nb);
1979 __initcall(init_uprobes);