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>
39 #include <linux/uprobes.h>
41 #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES)
42 #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE
44 static struct rb_root uprobes_tree = RB_ROOT;
46 * allows us to skip the uprobe_mmap if there are no uprobe events active
47 * at this time. Probably a fine grained per inode count is better?
49 #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree)
51 static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */
53 #define UPROBES_HASH_SZ 13
54 /* serialize uprobe->pending_list */
55 static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];
56 #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ])
58 static struct percpu_rw_semaphore dup_mmap_sem;
60 /* Have a copy of original instruction */
61 #define UPROBE_COPY_INSN 0
62 /* Can skip singlestep */
63 #define UPROBE_SKIP_SSTEP 1
66 struct rb_node rb_node; /* node in the rb tree */
68 struct rw_semaphore register_rwsem;
69 struct rw_semaphore consumer_rwsem;
70 struct list_head pending_list;
71 struct uprobe_consumer *consumers;
72 struct inode *inode; /* Also hold a ref to inode */
75 struct arch_uprobe arch;
78 struct return_instance {
79 struct uprobe *uprobe;
81 unsigned long orig_ret_vaddr; /* original return address */
82 bool chained; /* true, if instance is nested */
84 struct return_instance *next; /* keep as stack */
88 * valid_vma: Verify if the specified vma is an executable vma
89 * Relax restrictions while unregistering: vm_flags might have
90 * changed after breakpoint was inserted.
91 * - is_register: indicates if we are in register context.
92 * - Return 1 if the specified virtual address is in an
95 static bool valid_vma(struct vm_area_struct *vma, bool is_register)
97 vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED;
102 return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC;
105 static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset)
107 return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
110 static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr)
112 return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start);
116 * __replace_page - replace page in vma by new page.
117 * based on replace_page in mm/ksm.c
119 * @vma: vma that holds the pte pointing to page
120 * @addr: address the old @page is mapped at
121 * @page: the cowed page we are replacing by kpage
122 * @kpage: the modified page we replace page by
124 * Returns 0 on success, -EFAULT on failure.
126 static int __replace_page(struct vm_area_struct *vma, unsigned long addr,
127 struct page *page, struct page *kpage)
129 struct mm_struct *mm = vma->vm_mm;
133 /* For mmu_notifiers */
134 const unsigned long mmun_start = addr;
135 const unsigned long mmun_end = addr + PAGE_SIZE;
137 /* For try_to_free_swap() and munlock_vma_page() below */
140 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
142 ptep = page_check_address(page, mm, addr, &ptl, 0);
147 page_add_new_anon_rmap(kpage, vma, addr);
149 if (!PageAnon(page)) {
150 dec_mm_counter(mm, MM_FILEPAGES);
151 inc_mm_counter(mm, MM_ANONPAGES);
154 flush_cache_page(vma, addr, pte_pfn(*ptep));
155 ptep_clear_flush(vma, addr, ptep);
156 set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
158 page_remove_rmap(page);
159 if (!page_mapped(page))
160 try_to_free_swap(page);
161 pte_unmap_unlock(ptep, ptl);
163 if (vma->vm_flags & VM_LOCKED)
164 munlock_vma_page(page);
169 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
175 * is_swbp_insn - check if instruction is breakpoint instruction.
176 * @insn: instruction to be checked.
177 * Default implementation of is_swbp_insn
178 * Returns true if @insn is a breakpoint instruction.
180 bool __weak is_swbp_insn(uprobe_opcode_t *insn)
182 return *insn == UPROBE_SWBP_INSN;
186 * is_trap_insn - check if instruction is breakpoint instruction.
187 * @insn: instruction to be checked.
188 * Default implementation of is_trap_insn
189 * Returns true if @insn is a breakpoint instruction.
191 * This function is needed for the case where an architecture has multiple
192 * trap instructions (like powerpc).
194 bool __weak is_trap_insn(uprobe_opcode_t *insn)
196 return is_swbp_insn(insn);
199 static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len)
201 void *kaddr = kmap_atomic(page);
202 memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len);
203 kunmap_atomic(kaddr);
206 static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len)
208 void *kaddr = kmap_atomic(page);
209 memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len);
210 kunmap_atomic(kaddr);
213 static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
215 uprobe_opcode_t old_opcode;
219 * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here.
220 * We do not check if it is any other 'trap variant' which could
221 * be conditional trap instruction such as the one powerpc supports.
223 * The logic is that we do not care if the underlying instruction
224 * is a trap variant; uprobes always wins over any other (gdb)
227 copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
228 is_swbp = is_swbp_insn(&old_opcode);
230 if (is_swbp_insn(new_opcode)) {
231 if (is_swbp) /* register: already installed? */
234 if (!is_swbp) /* unregister: was it changed by us? */
243 * Expect the breakpoint instruction to be the smallest size instruction for
244 * the architecture. If an arch has variable length instruction and the
245 * breakpoint instruction is not of the smallest length instruction
246 * supported by that architecture then we need to modify is_trap_at_addr and
247 * write_opcode accordingly. This would never be a problem for archs that
248 * have fixed length instructions.
252 * write_opcode - write the opcode at a given virtual address.
253 * @mm: the probed process address space.
254 * @vaddr: the virtual address to store the opcode.
255 * @opcode: opcode to be written at @vaddr.
257 * Called with mm->mmap_sem held (for read and with a reference to
260 * For mm @mm, write the opcode at @vaddr.
261 * Return 0 (success) or a negative errno.
263 static int write_opcode(struct mm_struct *mm, unsigned long vaddr,
264 uprobe_opcode_t opcode)
266 struct page *old_page, *new_page;
267 struct vm_area_struct *vma;
271 /* Read the page with vaddr into memory */
272 ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma);
276 ret = verify_opcode(old_page, vaddr, &opcode);
281 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
285 __SetPageUptodate(new_page);
287 copy_highpage(new_page, old_page);
288 copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
290 ret = anon_vma_prepare(vma);
294 ret = __replace_page(vma, vaddr, old_page, new_page);
297 page_cache_release(new_page);
301 if (unlikely(ret == -EAGAIN))
307 * set_swbp - store breakpoint at a given address.
308 * @auprobe: arch specific probepoint information.
309 * @mm: the probed process address space.
310 * @vaddr: the virtual address to insert the opcode.
312 * For mm @mm, store the breakpoint instruction at @vaddr.
313 * Return 0 (success) or a negative errno.
315 int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
317 return write_opcode(mm, vaddr, UPROBE_SWBP_INSN);
321 * set_orig_insn - Restore the original instruction.
322 * @mm: the probed process address space.
323 * @auprobe: arch specific probepoint information.
324 * @vaddr: the virtual address to insert the opcode.
326 * For mm @mm, restore the original opcode (opcode) at @vaddr.
327 * Return 0 (success) or a negative errno.
330 set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr)
332 return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn);
335 static int match_uprobe(struct uprobe *l, struct uprobe *r)
337 if (l->inode < r->inode)
340 if (l->inode > r->inode)
343 if (l->offset < r->offset)
346 if (l->offset > r->offset)
352 static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset)
354 struct uprobe u = { .inode = inode, .offset = offset };
355 struct rb_node *n = uprobes_tree.rb_node;
356 struct uprobe *uprobe;
360 uprobe = rb_entry(n, struct uprobe, rb_node);
361 match = match_uprobe(&u, uprobe);
363 atomic_inc(&uprobe->ref);
376 * Find a uprobe corresponding to a given inode:offset
377 * Acquires uprobes_treelock
379 static struct uprobe *find_uprobe(struct inode *inode, loff_t offset)
381 struct uprobe *uprobe;
383 spin_lock(&uprobes_treelock);
384 uprobe = __find_uprobe(inode, offset);
385 spin_unlock(&uprobes_treelock);
390 static struct uprobe *__insert_uprobe(struct uprobe *uprobe)
392 struct rb_node **p = &uprobes_tree.rb_node;
393 struct rb_node *parent = NULL;
399 u = rb_entry(parent, struct uprobe, rb_node);
400 match = match_uprobe(uprobe, u);
407 p = &parent->rb_left;
409 p = &parent->rb_right;
414 rb_link_node(&uprobe->rb_node, parent, p);
415 rb_insert_color(&uprobe->rb_node, &uprobes_tree);
416 /* get access + creation ref */
417 atomic_set(&uprobe->ref, 2);
423 * Acquire uprobes_treelock.
424 * Matching uprobe already exists in rbtree;
425 * increment (access refcount) and return the matching uprobe.
427 * No matching uprobe; insert the uprobe in rb_tree;
428 * get a double refcount (access + creation) and return NULL.
430 static struct uprobe *insert_uprobe(struct uprobe *uprobe)
434 spin_lock(&uprobes_treelock);
435 u = __insert_uprobe(uprobe);
436 spin_unlock(&uprobes_treelock);
441 static void put_uprobe(struct uprobe *uprobe)
443 if (atomic_dec_and_test(&uprobe->ref))
447 static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset)
449 struct uprobe *uprobe, *cur_uprobe;
451 uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL);
455 uprobe->inode = igrab(inode);
456 uprobe->offset = offset;
457 init_rwsem(&uprobe->register_rwsem);
458 init_rwsem(&uprobe->consumer_rwsem);
459 /* For now assume that the instruction need not be single-stepped */
460 __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
462 /* add to uprobes_tree, sorted on inode:offset */
463 cur_uprobe = insert_uprobe(uprobe);
465 /* a uprobe exists for this inode:offset combination */
475 static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
477 down_write(&uprobe->consumer_rwsem);
478 uc->next = uprobe->consumers;
479 uprobe->consumers = uc;
480 up_write(&uprobe->consumer_rwsem);
484 * For uprobe @uprobe, delete the consumer @uc.
485 * Return true if the @uc is deleted successfully
488 static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc)
490 struct uprobe_consumer **con;
493 down_write(&uprobe->consumer_rwsem);
494 for (con = &uprobe->consumers; *con; con = &(*con)->next) {
501 up_write(&uprobe->consumer_rwsem);
507 __copy_insn(struct address_space *mapping, struct file *filp, char *insn,
508 unsigned long nbytes, loff_t offset)
512 if (!mapping->a_ops->readpage)
515 * Ensure that the page that has the original instruction is
516 * populated and in page-cache.
518 page = read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT, filp);
520 return PTR_ERR(page);
522 copy_from_page(page, offset, insn, nbytes);
523 page_cache_release(page);
528 static int copy_insn(struct uprobe *uprobe, struct file *filp)
530 struct address_space *mapping;
531 unsigned long nbytes;
534 nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK);
535 mapping = uprobe->inode->i_mapping;
537 /* Instruction at end of binary; copy only available bytes */
538 if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size)
539 bytes = uprobe->inode->i_size - uprobe->offset;
541 bytes = MAX_UINSN_BYTES;
543 /* Instruction at the page-boundary; copy bytes in second page */
544 if (nbytes < bytes) {
545 int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes,
546 bytes - nbytes, uprobe->offset + nbytes);
551 return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset);
554 static int prepare_uprobe(struct uprobe *uprobe, struct file *file,
555 struct mm_struct *mm, unsigned long vaddr)
559 if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
562 /* TODO: move this into _register, until then we abuse this sem. */
563 down_write(&uprobe->consumer_rwsem);
564 if (test_bit(UPROBE_COPY_INSN, &uprobe->flags))
567 ret = copy_insn(uprobe, file);
572 if (is_trap_insn((uprobe_opcode_t *)uprobe->arch.insn))
575 ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr);
579 /* write_opcode() assumes we don't cross page boundary */
580 BUG_ON((uprobe->offset & ~PAGE_MASK) +
581 UPROBE_SWBP_INSN_SIZE > PAGE_SIZE);
583 smp_wmb(); /* pairs with rmb() in find_active_uprobe() */
584 set_bit(UPROBE_COPY_INSN, &uprobe->flags);
587 up_write(&uprobe->consumer_rwsem);
592 static inline bool consumer_filter(struct uprobe_consumer *uc,
593 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
595 return !uc->filter || uc->filter(uc, ctx, mm);
598 static bool filter_chain(struct uprobe *uprobe,
599 enum uprobe_filter_ctx ctx, struct mm_struct *mm)
601 struct uprobe_consumer *uc;
604 down_read(&uprobe->consumer_rwsem);
605 for (uc = uprobe->consumers; uc; uc = uc->next) {
606 ret = consumer_filter(uc, ctx, mm);
610 up_read(&uprobe->consumer_rwsem);
616 install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm,
617 struct vm_area_struct *vma, unsigned long vaddr)
622 ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr);
627 * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(),
628 * the task can hit this breakpoint right after __replace_page().
630 first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags);
632 set_bit(MMF_HAS_UPROBES, &mm->flags);
634 ret = set_swbp(&uprobe->arch, mm, vaddr);
636 clear_bit(MMF_RECALC_UPROBES, &mm->flags);
637 else if (first_uprobe)
638 clear_bit(MMF_HAS_UPROBES, &mm->flags);
644 remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr)
646 set_bit(MMF_RECALC_UPROBES, &mm->flags);
647 return set_orig_insn(&uprobe->arch, mm, vaddr);
650 static inline bool uprobe_is_active(struct uprobe *uprobe)
652 return !RB_EMPTY_NODE(&uprobe->rb_node);
655 * There could be threads that have already hit the breakpoint. They
656 * will recheck the current insn and restart if find_uprobe() fails.
657 * See find_active_uprobe().
659 static void delete_uprobe(struct uprobe *uprobe)
661 if (WARN_ON(!uprobe_is_active(uprobe)))
664 spin_lock(&uprobes_treelock);
665 rb_erase(&uprobe->rb_node, &uprobes_tree);
666 spin_unlock(&uprobes_treelock);
667 RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */
673 struct map_info *next;
674 struct mm_struct *mm;
678 static inline struct map_info *free_map_info(struct map_info *info)
680 struct map_info *next = info->next;
685 static struct map_info *
686 build_map_info(struct address_space *mapping, loff_t offset, bool is_register)
688 unsigned long pgoff = offset >> PAGE_SHIFT;
689 struct vm_area_struct *vma;
690 struct map_info *curr = NULL;
691 struct map_info *prev = NULL;
692 struct map_info *info;
696 mutex_lock(&mapping->i_mmap_mutex);
697 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
698 if (!valid_vma(vma, is_register))
701 if (!prev && !more) {
703 * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through
704 * reclaim. This is optimistic, no harm done if it fails.
706 prev = kmalloc(sizeof(struct map_info),
707 GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN);
716 if (!atomic_inc_not_zero(&vma->vm_mm->mm_users))
724 info->mm = vma->vm_mm;
725 info->vaddr = offset_to_vaddr(vma, offset);
727 mutex_unlock(&mapping->i_mmap_mutex);
739 info = kmalloc(sizeof(struct map_info), GFP_KERNEL);
741 curr = ERR_PTR(-ENOMEM);
751 prev = free_map_info(prev);
756 register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new)
758 bool is_register = !!new;
759 struct map_info *info;
762 percpu_down_write(&dup_mmap_sem);
763 info = build_map_info(uprobe->inode->i_mapping,
764 uprobe->offset, is_register);
771 struct mm_struct *mm = info->mm;
772 struct vm_area_struct *vma;
774 if (err && is_register)
777 down_write(&mm->mmap_sem);
778 vma = find_vma(mm, info->vaddr);
779 if (!vma || !valid_vma(vma, is_register) ||
780 file_inode(vma->vm_file) != uprobe->inode)
783 if (vma->vm_start > info->vaddr ||
784 vaddr_to_offset(vma, info->vaddr) != uprobe->offset)
788 /* consult only the "caller", new consumer. */
789 if (consumer_filter(new,
790 UPROBE_FILTER_REGISTER, mm))
791 err = install_breakpoint(uprobe, mm, vma, info->vaddr);
792 } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) {
793 if (!filter_chain(uprobe,
794 UPROBE_FILTER_UNREGISTER, mm))
795 err |= remove_breakpoint(uprobe, mm, info->vaddr);
799 up_write(&mm->mmap_sem);
802 info = free_map_info(info);
805 percpu_up_write(&dup_mmap_sem);
809 static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
811 consumer_add(uprobe, uc);
812 return register_for_each_vma(uprobe, uc);
815 static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
819 if (!consumer_del(uprobe, uc)) /* WARN? */
822 err = register_for_each_vma(uprobe, NULL);
823 /* TODO : cant unregister? schedule a worker thread */
824 if (!uprobe->consumers && !err)
825 delete_uprobe(uprobe);
829 * uprobe_register - register a probe
830 * @inode: the file in which the probe has to be placed.
831 * @offset: offset from the start of the file.
832 * @uc: information on howto handle the probe..
834 * Apart from the access refcount, uprobe_register() takes a creation
835 * refcount (thro alloc_uprobe) if and only if this @uprobe is getting
836 * inserted into the rbtree (i.e first consumer for a @inode:@offset
837 * tuple). Creation refcount stops uprobe_unregister from freeing the
838 * @uprobe even before the register operation is complete. Creation
839 * refcount is released when the last @uc for the @uprobe
842 * Return errno if it cannot successully install probes
843 * else return 0 (success)
845 int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
847 struct uprobe *uprobe;
850 /* Uprobe must have at least one set consumer */
851 if (!uc->handler && !uc->ret_handler)
854 /* Racy, just to catch the obvious mistakes */
855 if (offset > i_size_read(inode))
859 uprobe = alloc_uprobe(inode, offset);
863 * We can race with uprobe_unregister()->delete_uprobe().
864 * Check uprobe_is_active() and retry if it is false.
866 down_write(&uprobe->register_rwsem);
868 if (likely(uprobe_is_active(uprobe))) {
869 ret = __uprobe_register(uprobe, uc);
871 __uprobe_unregister(uprobe, uc);
873 up_write(&uprobe->register_rwsem);
876 if (unlikely(ret == -EAGAIN))
880 EXPORT_SYMBOL_GPL(uprobe_register);
883 * uprobe_apply - unregister a already registered probe.
884 * @inode: the file in which the probe has to be removed.
885 * @offset: offset from the start of the file.
886 * @uc: consumer which wants to add more or remove some breakpoints
887 * @add: add or remove the breakpoints
889 int uprobe_apply(struct inode *inode, loff_t offset,
890 struct uprobe_consumer *uc, bool add)
892 struct uprobe *uprobe;
893 struct uprobe_consumer *con;
896 uprobe = find_uprobe(inode, offset);
900 down_write(&uprobe->register_rwsem);
901 for (con = uprobe->consumers; con && con != uc ; con = con->next)
904 ret = register_for_each_vma(uprobe, add ? uc : NULL);
905 up_write(&uprobe->register_rwsem);
912 * uprobe_unregister - unregister a already registered probe.
913 * @inode: the file in which the probe has to be removed.
914 * @offset: offset from the start of the file.
915 * @uc: identify which probe if multiple probes are colocated.
917 void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc)
919 struct uprobe *uprobe;
921 uprobe = find_uprobe(inode, offset);
925 down_write(&uprobe->register_rwsem);
926 __uprobe_unregister(uprobe, uc);
927 up_write(&uprobe->register_rwsem);
930 EXPORT_SYMBOL_GPL(uprobe_unregister);
932 static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
934 struct vm_area_struct *vma;
937 down_read(&mm->mmap_sem);
938 for (vma = mm->mmap; vma; vma = vma->vm_next) {
942 if (!valid_vma(vma, false) ||
943 file_inode(vma->vm_file) != uprobe->inode)
946 offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
947 if (uprobe->offset < offset ||
948 uprobe->offset >= offset + vma->vm_end - vma->vm_start)
951 vaddr = offset_to_vaddr(vma, uprobe->offset);
952 err |= remove_breakpoint(uprobe, mm, vaddr);
954 up_read(&mm->mmap_sem);
959 static struct rb_node *
960 find_node_in_range(struct inode *inode, loff_t min, loff_t max)
962 struct rb_node *n = uprobes_tree.rb_node;
965 struct uprobe *u = rb_entry(n, struct uprobe, rb_node);
967 if (inode < u->inode) {
969 } else if (inode > u->inode) {
974 else if (min > u->offset)
985 * For a given range in vma, build a list of probes that need to be inserted.
987 static void build_probe_list(struct inode *inode,
988 struct vm_area_struct *vma,
989 unsigned long start, unsigned long end,
990 struct list_head *head)
993 struct rb_node *n, *t;
996 INIT_LIST_HEAD(head);
997 min = vaddr_to_offset(vma, start);
998 max = min + (end - start) - 1;
1000 spin_lock(&uprobes_treelock);
1001 n = find_node_in_range(inode, min, max);
1003 for (t = n; t; t = rb_prev(t)) {
1004 u = rb_entry(t, struct uprobe, rb_node);
1005 if (u->inode != inode || u->offset < min)
1007 list_add(&u->pending_list, head);
1008 atomic_inc(&u->ref);
1010 for (t = n; (t = rb_next(t)); ) {
1011 u = rb_entry(t, struct uprobe, rb_node);
1012 if (u->inode != inode || u->offset > max)
1014 list_add(&u->pending_list, head);
1015 atomic_inc(&u->ref);
1018 spin_unlock(&uprobes_treelock);
1022 * Called from mmap_region/vma_adjust with mm->mmap_sem acquired.
1024 * Currently we ignore all errors and always return 0, the callers
1025 * can't handle the failure anyway.
1027 int uprobe_mmap(struct vm_area_struct *vma)
1029 struct list_head tmp_list;
1030 struct uprobe *uprobe, *u;
1031 struct inode *inode;
1033 if (no_uprobe_events() || !valid_vma(vma, true))
1036 inode = file_inode(vma->vm_file);
1040 mutex_lock(uprobes_mmap_hash(inode));
1041 build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list);
1043 * We can race with uprobe_unregister(), this uprobe can be already
1044 * removed. But in this case filter_chain() must return false, all
1045 * consumers have gone away.
1047 list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
1048 if (!fatal_signal_pending(current) &&
1049 filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) {
1050 unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset);
1051 install_breakpoint(uprobe, vma->vm_mm, vma, vaddr);
1055 mutex_unlock(uprobes_mmap_hash(inode));
1061 vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end)
1064 struct inode *inode;
1067 inode = file_inode(vma->vm_file);
1069 min = vaddr_to_offset(vma, start);
1070 max = min + (end - start) - 1;
1072 spin_lock(&uprobes_treelock);
1073 n = find_node_in_range(inode, min, max);
1074 spin_unlock(&uprobes_treelock);
1080 * Called in context of a munmap of a vma.
1082 void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end)
1084 if (no_uprobe_events() || !valid_vma(vma, false))
1087 if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */
1090 if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) ||
1091 test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags))
1094 if (vma_has_uprobes(vma, start, end))
1095 set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags);
1098 /* Slot allocation for XOL */
1099 static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
1101 int ret = -EALREADY;
1103 down_write(&mm->mmap_sem);
1104 if (mm->uprobes_state.xol_area)
1107 /* Try to map as high as possible, this is only a hint. */
1108 area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0);
1109 if (area->vaddr & ~PAGE_MASK) {
1114 ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE,
1115 VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page);
1119 smp_wmb(); /* pairs with get_xol_area() */
1120 mm->uprobes_state.xol_area = area;
1122 up_write(&mm->mmap_sem);
1127 static struct xol_area *__create_xol_area(void)
1129 struct mm_struct *mm = current->mm;
1130 uprobe_opcode_t insn = UPROBE_SWBP_INSN;
1131 struct xol_area *area;
1133 area = kzalloc(sizeof(*area), GFP_KERNEL);
1134 if (unlikely(!area))
1137 area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL);
1141 area->page = alloc_page(GFP_HIGHUSER);
1145 init_waitqueue_head(&area->wq);
1146 /* Reserve the 1st slot for get_trampoline_vaddr() */
1147 set_bit(0, area->bitmap);
1148 atomic_set(&area->slot_count, 1);
1149 copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE);
1151 if (!xol_add_vma(mm, area))
1154 __free_page(area->page);
1156 kfree(area->bitmap);
1164 * get_xol_area - Allocate process's xol_area if necessary.
1165 * This area will be used for storing instructions for execution out of line.
1167 * Returns the allocated area or NULL.
1169 static struct xol_area *get_xol_area(void)
1171 struct mm_struct *mm = current->mm;
1172 struct xol_area *area;
1174 if (!mm->uprobes_state.xol_area)
1175 __create_xol_area();
1177 area = mm->uprobes_state.xol_area;
1178 smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
1183 * uprobe_clear_state - Free the area allocated for slots.
1185 void uprobe_clear_state(struct mm_struct *mm)
1187 struct xol_area *area = mm->uprobes_state.xol_area;
1192 put_page(area->page);
1193 kfree(area->bitmap);
1197 void uprobe_start_dup_mmap(void)
1199 percpu_down_read(&dup_mmap_sem);
1202 void uprobe_end_dup_mmap(void)
1204 percpu_up_read(&dup_mmap_sem);
1207 void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm)
1209 newmm->uprobes_state.xol_area = NULL;
1211 if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) {
1212 set_bit(MMF_HAS_UPROBES, &newmm->flags);
1213 /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */
1214 set_bit(MMF_RECALC_UPROBES, &newmm->flags);
1219 * - search for a free slot.
1221 static unsigned long xol_take_insn_slot(struct xol_area *area)
1223 unsigned long slot_addr;
1227 slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE);
1228 if (slot_nr < UINSNS_PER_PAGE) {
1229 if (!test_and_set_bit(slot_nr, area->bitmap))
1232 slot_nr = UINSNS_PER_PAGE;
1235 wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE));
1236 } while (slot_nr >= UINSNS_PER_PAGE);
1238 slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES);
1239 atomic_inc(&area->slot_count);
1245 * xol_get_insn_slot - allocate a slot for xol.
1246 * Returns the allocated slot address or 0.
1248 static unsigned long xol_get_insn_slot(struct uprobe *uprobe)
1250 struct xol_area *area;
1251 unsigned long xol_vaddr;
1253 area = get_xol_area();
1257 xol_vaddr = xol_take_insn_slot(area);
1258 if (unlikely(!xol_vaddr))
1261 /* Initialize the slot */
1262 copy_to_page(area->page, xol_vaddr, uprobe->arch.insn, MAX_UINSN_BYTES);
1264 * We probably need flush_icache_user_range() but it needs vma.
1265 * This should work on supported architectures too.
1267 flush_dcache_page(area->page);
1273 * xol_free_insn_slot - If slot was earlier allocated by
1274 * @xol_get_insn_slot(), make the slot available for
1275 * subsequent requests.
1277 static void xol_free_insn_slot(struct task_struct *tsk)
1279 struct xol_area *area;
1280 unsigned long vma_end;
1281 unsigned long slot_addr;
1283 if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask)
1286 slot_addr = tsk->utask->xol_vaddr;
1287 if (unlikely(!slot_addr))
1290 area = tsk->mm->uprobes_state.xol_area;
1291 vma_end = area->vaddr + PAGE_SIZE;
1292 if (area->vaddr <= slot_addr && slot_addr < vma_end) {
1293 unsigned long offset;
1296 offset = slot_addr - area->vaddr;
1297 slot_nr = offset / UPROBE_XOL_SLOT_BYTES;
1298 if (slot_nr >= UINSNS_PER_PAGE)
1301 clear_bit(slot_nr, area->bitmap);
1302 atomic_dec(&area->slot_count);
1303 if (waitqueue_active(&area->wq))
1306 tsk->utask->xol_vaddr = 0;
1311 * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs
1312 * @regs: Reflects the saved state of the task after it has hit a breakpoint
1314 * Return the address of the breakpoint instruction.
1316 unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs)
1318 return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE;
1322 * Called with no locks held.
1323 * Called in context of a exiting or a exec-ing thread.
1325 void uprobe_free_utask(struct task_struct *t)
1327 struct uprobe_task *utask = t->utask;
1328 struct return_instance *ri, *tmp;
1333 if (utask->active_uprobe)
1334 put_uprobe(utask->active_uprobe);
1336 ri = utask->return_instances;
1341 put_uprobe(tmp->uprobe);
1345 xol_free_insn_slot(t);
1351 * Allocate a uprobe_task object for the task if if necessary.
1352 * Called when the thread hits a breakpoint.
1355 * - pointer to new uprobe_task on success
1358 static struct uprobe_task *get_utask(void)
1360 if (!current->utask)
1361 current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
1362 return current->utask;
1366 * Called in context of a new clone/fork from copy_process.
1368 void uprobe_copy_process(struct task_struct *t)
1374 * Current area->vaddr notion assume the trampoline address is always
1375 * equal area->vaddr.
1377 * Returns -1 in case the xol_area is not allocated.
1379 static unsigned long get_trampoline_vaddr(void)
1381 struct xol_area *area;
1382 unsigned long trampoline_vaddr = -1;
1384 area = current->mm->uprobes_state.xol_area;
1385 smp_read_barrier_depends();
1387 trampoline_vaddr = area->vaddr;
1389 return trampoline_vaddr;
1392 static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs)
1394 struct return_instance *ri;
1395 struct uprobe_task *utask;
1396 unsigned long orig_ret_vaddr, trampoline_vaddr;
1397 bool chained = false;
1399 if (!get_xol_area())
1402 utask = get_utask();
1406 if (utask->depth >= MAX_URETPROBE_DEPTH) {
1407 printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to"
1408 " nestedness limit pid/tgid=%d/%d\n",
1409 current->pid, current->tgid);
1413 ri = kzalloc(sizeof(struct return_instance), GFP_KERNEL);
1417 trampoline_vaddr = get_trampoline_vaddr();
1418 orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs);
1419 if (orig_ret_vaddr == -1)
1423 * We don't want to keep trampoline address in stack, rather keep the
1424 * original return address of first caller thru all the consequent
1425 * instances. This also makes breakpoint unwrapping easier.
1427 if (orig_ret_vaddr == trampoline_vaddr) {
1428 if (!utask->return_instances) {
1430 * This situation is not possible. Likely we have an
1431 * attack from user-space.
1433 pr_warn("uprobe: unable to set uretprobe pid/tgid=%d/%d\n",
1434 current->pid, current->tgid);
1439 orig_ret_vaddr = utask->return_instances->orig_ret_vaddr;
1442 atomic_inc(&uprobe->ref);
1443 ri->uprobe = uprobe;
1444 ri->func = instruction_pointer(regs);
1445 ri->orig_ret_vaddr = orig_ret_vaddr;
1446 ri->chained = chained;
1450 /* add instance to the stack */
1451 ri->next = utask->return_instances;
1452 utask->return_instances = ri;
1460 /* Prepare to single-step probed instruction out of line. */
1462 pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr)
1464 struct uprobe_task *utask;
1465 unsigned long xol_vaddr;
1468 utask = get_utask();
1472 xol_vaddr = xol_get_insn_slot(uprobe);
1476 utask->xol_vaddr = xol_vaddr;
1477 utask->vaddr = bp_vaddr;
1479 err = arch_uprobe_pre_xol(&uprobe->arch, regs);
1480 if (unlikely(err)) {
1481 xol_free_insn_slot(current);
1485 utask->active_uprobe = uprobe;
1486 utask->state = UTASK_SSTEP;
1491 * If we are singlestepping, then ensure this thread is not connected to
1492 * non-fatal signals until completion of singlestep. When xol insn itself
1493 * triggers the signal, restart the original insn even if the task is
1494 * already SIGKILL'ed (since coredump should report the correct ip). This
1495 * is even more important if the task has a handler for SIGSEGV/etc, The
1496 * _same_ instruction should be repeated again after return from the signal
1497 * handler, and SSTEP can never finish in this case.
1499 bool uprobe_deny_signal(void)
1501 struct task_struct *t = current;
1502 struct uprobe_task *utask = t->utask;
1504 if (likely(!utask || !utask->active_uprobe))
1507 WARN_ON_ONCE(utask->state != UTASK_SSTEP);
1509 if (signal_pending(t)) {
1510 spin_lock_irq(&t->sighand->siglock);
1511 clear_tsk_thread_flag(t, TIF_SIGPENDING);
1512 spin_unlock_irq(&t->sighand->siglock);
1514 if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) {
1515 utask->state = UTASK_SSTEP_TRAPPED;
1516 set_tsk_thread_flag(t, TIF_UPROBE);
1517 set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
1525 * Avoid singlestepping the original instruction if the original instruction
1526 * is a NOP or can be emulated.
1528 static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs)
1530 if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) {
1531 if (arch_uprobe_skip_sstep(&uprobe->arch, regs))
1533 clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags);
1538 static void mmf_recalc_uprobes(struct mm_struct *mm)
1540 struct vm_area_struct *vma;
1542 for (vma = mm->mmap; vma; vma = vma->vm_next) {
1543 if (!valid_vma(vma, false))
1546 * This is not strictly accurate, we can race with
1547 * uprobe_unregister() and see the already removed
1548 * uprobe if delete_uprobe() was not yet called.
1549 * Or this uprobe can be filtered out.
1551 if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end))
1555 clear_bit(MMF_HAS_UPROBES, &mm->flags);
1558 static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
1561 uprobe_opcode_t opcode;
1564 pagefault_disable();
1565 result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr,
1569 if (likely(result == 0))
1572 result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL);
1576 copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
1579 /* This needs to return true for any variant of the trap insn */
1580 return is_trap_insn(&opcode);
1583 static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp)
1585 struct mm_struct *mm = current->mm;
1586 struct uprobe *uprobe = NULL;
1587 struct vm_area_struct *vma;
1589 down_read(&mm->mmap_sem);
1590 vma = find_vma(mm, bp_vaddr);
1591 if (vma && vma->vm_start <= bp_vaddr) {
1592 if (valid_vma(vma, false)) {
1593 struct inode *inode = file_inode(vma->vm_file);
1594 loff_t offset = vaddr_to_offset(vma, bp_vaddr);
1596 uprobe = find_uprobe(inode, offset);
1600 *is_swbp = is_trap_at_addr(mm, bp_vaddr);
1605 if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags))
1606 mmf_recalc_uprobes(mm);
1607 up_read(&mm->mmap_sem);
1612 static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
1614 struct uprobe_consumer *uc;
1615 int remove = UPROBE_HANDLER_REMOVE;
1616 bool need_prep = false; /* prepare return uprobe, when needed */
1618 down_read(&uprobe->register_rwsem);
1619 for (uc = uprobe->consumers; uc; uc = uc->next) {
1623 rc = uc->handler(uc, regs);
1624 WARN(rc & ~UPROBE_HANDLER_MASK,
1625 "bad rc=0x%x from %pf()\n", rc, uc->handler);
1628 if (uc->ret_handler)
1634 if (need_prep && !remove)
1635 prepare_uretprobe(uprobe, regs); /* put bp at return */
1637 if (remove && uprobe->consumers) {
1638 WARN_ON(!uprobe_is_active(uprobe));
1639 unapply_uprobe(uprobe, current->mm);
1641 up_read(&uprobe->register_rwsem);
1645 handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs)
1647 struct uprobe *uprobe = ri->uprobe;
1648 struct uprobe_consumer *uc;
1650 down_read(&uprobe->register_rwsem);
1651 for (uc = uprobe->consumers; uc; uc = uc->next) {
1652 if (uc->ret_handler)
1653 uc->ret_handler(uc, ri->func, regs);
1655 up_read(&uprobe->register_rwsem);
1658 static bool handle_trampoline(struct pt_regs *regs)
1660 struct uprobe_task *utask;
1661 struct return_instance *ri, *tmp;
1664 utask = current->utask;
1668 ri = utask->return_instances;
1673 * TODO: we should throw out return_instance's invalidated by
1674 * longjmp(), currently we assume that the probed function always
1677 instruction_pointer_set(regs, ri->orig_ret_vaddr);
1680 handle_uretprobe_chain(ri, regs);
1682 chained = ri->chained;
1683 put_uprobe(ri->uprobe);
1695 utask->return_instances = ri;
1701 * Run handler and ask thread to singlestep.
1702 * Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
1704 static void handle_swbp(struct pt_regs *regs)
1706 struct uprobe *uprobe;
1707 unsigned long bp_vaddr;
1708 int uninitialized_var(is_swbp);
1710 bp_vaddr = uprobe_get_swbp_addr(regs);
1711 if (bp_vaddr == get_trampoline_vaddr()) {
1712 if (handle_trampoline(regs))
1715 pr_warn("uprobe: unable to handle uretprobe pid/tgid=%d/%d\n",
1716 current->pid, current->tgid);
1719 uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
1722 /* No matching uprobe; signal SIGTRAP. */
1723 send_sig(SIGTRAP, current, 0);
1726 * Either we raced with uprobe_unregister() or we can't
1727 * access this memory. The latter is only possible if
1728 * another thread plays with our ->mm. In both cases
1729 * we can simply restart. If this vma was unmapped we
1730 * can pretend this insn was not executed yet and get
1731 * the (correct) SIGSEGV after restart.
1733 instruction_pointer_set(regs, bp_vaddr);
1738 /* change it in advance for ->handler() and restart */
1739 instruction_pointer_set(regs, bp_vaddr);
1742 * TODO: move copy_insn/etc into _register and remove this hack.
1743 * After we hit the bp, _unregister + _register can install the
1744 * new and not-yet-analyzed uprobe at the same address, restart.
1746 smp_rmb(); /* pairs with wmb() in install_breakpoint() */
1747 if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
1750 handler_chain(uprobe, regs);
1751 if (can_skip_sstep(uprobe, regs))
1754 if (!pre_ssout(uprobe, regs, bp_vaddr))
1757 /* can_skip_sstep() succeeded, or restart if can't singlestep */
1763 * Perform required fix-ups and disable singlestep.
1764 * Allow pending signals to take effect.
1766 static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs)
1768 struct uprobe *uprobe;
1770 uprobe = utask->active_uprobe;
1771 if (utask->state == UTASK_SSTEP_ACK)
1772 arch_uprobe_post_xol(&uprobe->arch, regs);
1773 else if (utask->state == UTASK_SSTEP_TRAPPED)
1774 arch_uprobe_abort_xol(&uprobe->arch, regs);
1779 utask->active_uprobe = NULL;
1780 utask->state = UTASK_RUNNING;
1781 xol_free_insn_slot(current);
1783 spin_lock_irq(¤t->sighand->siglock);
1784 recalc_sigpending(); /* see uprobe_deny_signal() */
1785 spin_unlock_irq(¤t->sighand->siglock);
1789 * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and
1790 * allows the thread to return from interrupt. After that handle_swbp()
1791 * sets utask->active_uprobe.
1793 * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag
1794 * and allows the thread to return from interrupt.
1796 * While returning to userspace, thread notices the TIF_UPROBE flag and calls
1797 * uprobe_notify_resume().
1799 void uprobe_notify_resume(struct pt_regs *regs)
1801 struct uprobe_task *utask;
1803 clear_thread_flag(TIF_UPROBE);
1805 utask = current->utask;
1806 if (utask && utask->active_uprobe)
1807 handle_singlestep(utask, regs);
1813 * uprobe_pre_sstep_notifier gets called from interrupt context as part of
1814 * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit.
1816 int uprobe_pre_sstep_notifier(struct pt_regs *regs)
1821 if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) &&
1822 (!current->utask || !current->utask->return_instances))
1825 set_thread_flag(TIF_UPROBE);
1830 * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier
1831 * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep.
1833 int uprobe_post_sstep_notifier(struct pt_regs *regs)
1835 struct uprobe_task *utask = current->utask;
1837 if (!current->mm || !utask || !utask->active_uprobe)
1838 /* task is currently not uprobed */
1841 utask->state = UTASK_SSTEP_ACK;
1842 set_thread_flag(TIF_UPROBE);
1846 static struct notifier_block uprobe_exception_nb = {
1847 .notifier_call = arch_uprobe_exception_notify,
1848 .priority = INT_MAX-1, /* notified after kprobes, kgdb */
1851 static int __init init_uprobes(void)
1855 for (i = 0; i < UPROBES_HASH_SZ; i++)
1856 mutex_init(&uprobes_mmap_mutex[i]);
1858 if (percpu_init_rwsem(&dup_mmap_sem))
1861 return register_die_notifier(&uprobe_exception_nb);
1863 module_init(init_uprobes);
1865 static void __exit exit_uprobes(void)
1868 module_exit(exit_uprobes);