1a5f4374aSIngo Molnar /* 2a5f4374aSIngo Molnar * User-space Probes (UProbes) 3a5f4374aSIngo Molnar * 4a5f4374aSIngo Molnar * This program is free software; you can redistribute it and/or modify 5a5f4374aSIngo Molnar * it under the terms of the GNU General Public License as published by 6a5f4374aSIngo Molnar * the Free Software Foundation; either version 2 of the License, or 7a5f4374aSIngo Molnar * (at your option) any later version. 8a5f4374aSIngo Molnar * 9a5f4374aSIngo Molnar * This program is distributed in the hope that it will be useful, 10a5f4374aSIngo Molnar * but WITHOUT ANY WARRANTY; without even the implied warranty of 11a5f4374aSIngo Molnar * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12a5f4374aSIngo Molnar * GNU General Public License for more details. 13a5f4374aSIngo Molnar * 14a5f4374aSIngo Molnar * You should have received a copy of the GNU General Public License 15a5f4374aSIngo Molnar * along with this program; if not, write to the Free Software 16a5f4374aSIngo Molnar * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 17a5f4374aSIngo Molnar * 1835aa621bSIngo Molnar * Copyright (C) IBM Corporation, 2008-2012 19a5f4374aSIngo Molnar * Authors: 20a5f4374aSIngo Molnar * Srikar Dronamraju 21a5f4374aSIngo Molnar * Jim Keniston 2235aa621bSIngo Molnar * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com> 23a5f4374aSIngo Molnar */ 24a5f4374aSIngo Molnar 25a5f4374aSIngo Molnar #include <linux/kernel.h> 26a5f4374aSIngo Molnar #include <linux/highmem.h> 27a5f4374aSIngo Molnar #include <linux/pagemap.h> /* read_mapping_page */ 28a5f4374aSIngo Molnar #include <linux/slab.h> 29a5f4374aSIngo Molnar #include <linux/sched.h> 30a5f4374aSIngo Molnar #include <linux/rmap.h> /* anon_vma_prepare */ 31a5f4374aSIngo Molnar #include <linux/mmu_notifier.h> /* set_pte_at_notify */ 32a5f4374aSIngo Molnar #include <linux/swap.h> /* try_to_free_swap */ 330326f5a9SSrikar Dronamraju #include <linux/ptrace.h> /* user_enable_single_step */ 340326f5a9SSrikar Dronamraju #include <linux/kdebug.h> /* notifier mechanism */ 35194f8dcbSOleg Nesterov #include "../../mm/internal.h" /* munlock_vma_page */ 3632cdba1eSOleg Nesterov #include <linux/percpu-rwsem.h> 37a5f4374aSIngo Molnar 38a5f4374aSIngo Molnar #include <linux/uprobes.h> 39a5f4374aSIngo Molnar 40d4b3b638SSrikar Dronamraju #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) 41d4b3b638SSrikar Dronamraju #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE 42d4b3b638SSrikar Dronamraju 43a5f4374aSIngo Molnar static struct rb_root uprobes_tree = RB_ROOT; 44441f1eb7SOleg Nesterov /* 45441f1eb7SOleg Nesterov * allows us to skip the uprobe_mmap if there are no uprobe events active 46441f1eb7SOleg Nesterov * at this time. Probably a fine grained per inode count is better? 47441f1eb7SOleg Nesterov */ 48441f1eb7SOleg Nesterov #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) 49a5f4374aSIngo Molnar 50a5f4374aSIngo Molnar static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ 51a5f4374aSIngo Molnar 52a5f4374aSIngo Molnar #define UPROBES_HASH_SZ 13 53a5f4374aSIngo Molnar /* serialize uprobe->pending_list */ 54a5f4374aSIngo Molnar static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; 55a5f4374aSIngo Molnar #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 56a5f4374aSIngo Molnar 5732cdba1eSOleg Nesterov static struct percpu_rw_semaphore dup_mmap_sem; 5832cdba1eSOleg Nesterov 59cb9a19feSOleg Nesterov /* Have a copy of original instruction */ 6071434f2fSOleg Nesterov #define UPROBE_COPY_INSN 0 61cb9a19feSOleg Nesterov /* Can skip singlestep */ 62bb929284SOleg Nesterov #define UPROBE_SKIP_SSTEP 1 63cb9a19feSOleg Nesterov 643ff54efdSSrikar Dronamraju struct uprobe { 653ff54efdSSrikar Dronamraju struct rb_node rb_node; /* node in the rb tree */ 663ff54efdSSrikar Dronamraju atomic_t ref; 67e591c8d7SOleg Nesterov struct rw_semaphore register_rwsem; 683ff54efdSSrikar Dronamraju struct rw_semaphore consumer_rwsem; 693ff54efdSSrikar Dronamraju struct list_head pending_list; 703ff54efdSSrikar Dronamraju struct uprobe_consumer *consumers; 713ff54efdSSrikar Dronamraju struct inode *inode; /* Also hold a ref to inode */ 723ff54efdSSrikar Dronamraju loff_t offset; 7371434f2fSOleg Nesterov unsigned long flags; 743ff54efdSSrikar Dronamraju struct arch_uprobe arch; 753ff54efdSSrikar Dronamraju }; 763ff54efdSSrikar Dronamraju 77a5f4374aSIngo Molnar /* 78a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 79a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 80a5f4374aSIngo Molnar * changed after breakpoint was inserted. 81a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 82a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 83a5f4374aSIngo Molnar * executable vma. 84a5f4374aSIngo Molnar */ 85a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 86a5f4374aSIngo Molnar { 87e40cfce6SOleg Nesterov vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; 88a5f4374aSIngo Molnar 89e40cfce6SOleg Nesterov if (is_register) 90e40cfce6SOleg Nesterov flags |= VM_WRITE; 91a5f4374aSIngo Molnar 92e40cfce6SOleg Nesterov return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; 93a5f4374aSIngo Molnar } 94a5f4374aSIngo Molnar 9557683f72SOleg Nesterov static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) 96a5f4374aSIngo Molnar { 9757683f72SOleg Nesterov return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); 98a5f4374aSIngo Molnar } 99a5f4374aSIngo Molnar 100cb113b47SOleg Nesterov static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) 101cb113b47SOleg Nesterov { 102cb113b47SOleg Nesterov return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); 103cb113b47SOleg Nesterov } 104cb113b47SOleg Nesterov 105a5f4374aSIngo Molnar /** 106a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 107a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 108a5f4374aSIngo Molnar * 109a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 110c517ee74SOleg Nesterov * @addr: address the old @page is mapped at 111a5f4374aSIngo Molnar * @page: the cowed page we are replacing by kpage 112a5f4374aSIngo Molnar * @kpage: the modified page we replace page by 113a5f4374aSIngo Molnar * 114a5f4374aSIngo Molnar * Returns 0 on success, -EFAULT on failure. 115a5f4374aSIngo Molnar */ 116c517ee74SOleg Nesterov static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 117c517ee74SOleg Nesterov struct page *page, struct page *kpage) 118a5f4374aSIngo Molnar { 119a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 1205323ce71SOleg Nesterov spinlock_t *ptl; 1215323ce71SOleg Nesterov pte_t *ptep; 1229f92448cSOleg Nesterov int err; 1236bdb913fSHaggai Eran /* For mmu_notifiers */ 1246bdb913fSHaggai Eran const unsigned long mmun_start = addr; 1256bdb913fSHaggai Eran const unsigned long mmun_end = addr + PAGE_SIZE; 126a5f4374aSIngo Molnar 127194f8dcbSOleg Nesterov /* For try_to_free_swap() and munlock_vma_page() below */ 1289f92448cSOleg Nesterov lock_page(page); 1299f92448cSOleg Nesterov 1306bdb913fSHaggai Eran mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 1319f92448cSOleg Nesterov err = -EAGAIN; 1325323ce71SOleg Nesterov ptep = page_check_address(page, mm, addr, &ptl, 0); 133a5f4374aSIngo Molnar if (!ptep) 1349f92448cSOleg Nesterov goto unlock; 135a5f4374aSIngo Molnar 136a5f4374aSIngo Molnar get_page(kpage); 137a5f4374aSIngo Molnar page_add_new_anon_rmap(kpage, vma, addr); 138a5f4374aSIngo Molnar 1397396fa81SSrikar Dronamraju if (!PageAnon(page)) { 1407396fa81SSrikar Dronamraju dec_mm_counter(mm, MM_FILEPAGES); 1417396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1427396fa81SSrikar Dronamraju } 1437396fa81SSrikar Dronamraju 144a5f4374aSIngo Molnar flush_cache_page(vma, addr, pte_pfn(*ptep)); 145a5f4374aSIngo Molnar ptep_clear_flush(vma, addr, ptep); 146a5f4374aSIngo Molnar set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); 147a5f4374aSIngo Molnar 148a5f4374aSIngo Molnar page_remove_rmap(page); 149a5f4374aSIngo Molnar if (!page_mapped(page)) 150a5f4374aSIngo Molnar try_to_free_swap(page); 151a5f4374aSIngo Molnar pte_unmap_unlock(ptep, ptl); 152a5f4374aSIngo Molnar 153194f8dcbSOleg Nesterov if (vma->vm_flags & VM_LOCKED) 154194f8dcbSOleg Nesterov munlock_vma_page(page); 155194f8dcbSOleg Nesterov put_page(page); 156194f8dcbSOleg Nesterov 1579f92448cSOleg Nesterov err = 0; 1589f92448cSOleg Nesterov unlock: 1596bdb913fSHaggai Eran mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 1609f92448cSOleg Nesterov unlock_page(page); 1619f92448cSOleg Nesterov return err; 162a5f4374aSIngo Molnar } 163a5f4374aSIngo Molnar 164a5f4374aSIngo Molnar /** 1655cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 166a5f4374aSIngo Molnar * @insn: instruction to be checked. 1675cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 168a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 169a5f4374aSIngo Molnar */ 1705cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 171a5f4374aSIngo Molnar { 1725cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 173a5f4374aSIngo Molnar } 174a5f4374aSIngo Molnar 175cceb55aaSOleg Nesterov static void copy_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *opcode) 176cceb55aaSOleg Nesterov { 177cceb55aaSOleg Nesterov void *kaddr = kmap_atomic(page); 178cceb55aaSOleg Nesterov memcpy(opcode, kaddr + (vaddr & ~PAGE_MASK), UPROBE_SWBP_INSN_SIZE); 179cceb55aaSOleg Nesterov kunmap_atomic(kaddr); 180cceb55aaSOleg Nesterov } 181cceb55aaSOleg Nesterov 182ed6f6a50SOleg Nesterov static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) 183ed6f6a50SOleg Nesterov { 184ed6f6a50SOleg Nesterov uprobe_opcode_t old_opcode; 185ed6f6a50SOleg Nesterov bool is_swbp; 186ed6f6a50SOleg Nesterov 187ed6f6a50SOleg Nesterov copy_opcode(page, vaddr, &old_opcode); 188ed6f6a50SOleg Nesterov is_swbp = is_swbp_insn(&old_opcode); 189ed6f6a50SOleg Nesterov 190ed6f6a50SOleg Nesterov if (is_swbp_insn(new_opcode)) { 191ed6f6a50SOleg Nesterov if (is_swbp) /* register: already installed? */ 192ed6f6a50SOleg Nesterov return 0; 193ed6f6a50SOleg Nesterov } else { 194ed6f6a50SOleg Nesterov if (!is_swbp) /* unregister: was it changed by us? */ 195076a365bSOleg Nesterov return 0; 196ed6f6a50SOleg Nesterov } 197ed6f6a50SOleg Nesterov 198ed6f6a50SOleg Nesterov return 1; 199ed6f6a50SOleg Nesterov } 200ed6f6a50SOleg Nesterov 201a5f4374aSIngo Molnar /* 202a5f4374aSIngo Molnar * NOTE: 203a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 204a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 205a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 206cceb55aaSOleg Nesterov * supported by that architecture then we need to modify is_swbp_at_addr and 207a5f4374aSIngo Molnar * write_opcode accordingly. This would never be a problem for archs that 208a5f4374aSIngo Molnar * have fixed length instructions. 209a5f4374aSIngo Molnar */ 210a5f4374aSIngo Molnar 211a5f4374aSIngo Molnar /* 212a5f4374aSIngo Molnar * write_opcode - write the opcode at a given virtual address. 213a5f4374aSIngo Molnar * @mm: the probed process address space. 214a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 215a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 216a5f4374aSIngo Molnar * 217a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 218a5f4374aSIngo Molnar * mm). 219a5f4374aSIngo Molnar * 220a5f4374aSIngo Molnar * For mm @mm, write the opcode at @vaddr. 221a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 222a5f4374aSIngo Molnar */ 223cceb55aaSOleg Nesterov static int write_opcode(struct mm_struct *mm, unsigned long vaddr, 224cceb55aaSOleg Nesterov uprobe_opcode_t opcode) 225a5f4374aSIngo Molnar { 226a5f4374aSIngo Molnar struct page *old_page, *new_page; 227a5f4374aSIngo Molnar void *vaddr_old, *vaddr_new; 228a5f4374aSIngo Molnar struct vm_area_struct *vma; 229a5f4374aSIngo Molnar int ret; 230f403072cSOleg Nesterov 2315323ce71SOleg Nesterov retry: 232a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 23375ed82eaSOleg Nesterov ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); 234a5f4374aSIngo Molnar if (ret <= 0) 235a5f4374aSIngo Molnar return ret; 236a5f4374aSIngo Molnar 237ed6f6a50SOleg Nesterov ret = verify_opcode(old_page, vaddr, &opcode); 238ed6f6a50SOleg Nesterov if (ret <= 0) 239ed6f6a50SOleg Nesterov goto put_old; 240ed6f6a50SOleg Nesterov 241a5f4374aSIngo Molnar ret = -ENOMEM; 242a5f4374aSIngo Molnar new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); 243a5f4374aSIngo Molnar if (!new_page) 2449f92448cSOleg Nesterov goto put_old; 245a5f4374aSIngo Molnar 246a5f4374aSIngo Molnar __SetPageUptodate(new_page); 247a5f4374aSIngo Molnar 248a5f4374aSIngo Molnar /* copy the page now that we've got it stable */ 249a5f4374aSIngo Molnar vaddr_old = kmap_atomic(old_page); 250a5f4374aSIngo Molnar vaddr_new = kmap_atomic(new_page); 251a5f4374aSIngo Molnar 252a5f4374aSIngo Molnar memcpy(vaddr_new, vaddr_old, PAGE_SIZE); 253d9c4a30eSOleg Nesterov memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE); 254a5f4374aSIngo Molnar 255a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 256a5f4374aSIngo Molnar kunmap_atomic(vaddr_old); 257a5f4374aSIngo Molnar 258a5f4374aSIngo Molnar ret = anon_vma_prepare(vma); 259a5f4374aSIngo Molnar if (ret) 2609f92448cSOleg Nesterov goto put_new; 261a5f4374aSIngo Molnar 262c517ee74SOleg Nesterov ret = __replace_page(vma, vaddr, old_page, new_page); 263a5f4374aSIngo Molnar 2649f92448cSOleg Nesterov put_new: 265a5f4374aSIngo Molnar page_cache_release(new_page); 2669f92448cSOleg Nesterov put_old: 267a5f4374aSIngo Molnar put_page(old_page); 268a5f4374aSIngo Molnar 2695323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 2705323ce71SOleg Nesterov goto retry; 271a5f4374aSIngo Molnar return ret; 272a5f4374aSIngo Molnar } 273a5f4374aSIngo Molnar 274a5f4374aSIngo Molnar /** 2755cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 276e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 277a5f4374aSIngo Molnar * @mm: the probed process address space. 278a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 279a5f4374aSIngo Molnar * 280a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 281a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 282a5f4374aSIngo Molnar */ 2835cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 284a5f4374aSIngo Molnar { 285cceb55aaSOleg Nesterov return write_opcode(mm, vaddr, UPROBE_SWBP_INSN); 286a5f4374aSIngo Molnar } 287a5f4374aSIngo Molnar 288a5f4374aSIngo Molnar /** 289a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 290a5f4374aSIngo Molnar * @mm: the probed process address space. 291e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 292a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 293a5f4374aSIngo Molnar * 294a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 295a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 296a5f4374aSIngo Molnar */ 297a5f4374aSIngo Molnar int __weak 298ded86e7cSOleg Nesterov set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 299a5f4374aSIngo Molnar { 300cceb55aaSOleg Nesterov return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); 301a5f4374aSIngo Molnar } 302a5f4374aSIngo Molnar 303a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 304a5f4374aSIngo Molnar { 305a5f4374aSIngo Molnar if (l->inode < r->inode) 306a5f4374aSIngo Molnar return -1; 307a5f4374aSIngo Molnar 308a5f4374aSIngo Molnar if (l->inode > r->inode) 309a5f4374aSIngo Molnar return 1; 310a5f4374aSIngo Molnar 311a5f4374aSIngo Molnar if (l->offset < r->offset) 312a5f4374aSIngo Molnar return -1; 313a5f4374aSIngo Molnar 314a5f4374aSIngo Molnar if (l->offset > r->offset) 315a5f4374aSIngo Molnar return 1; 316a5f4374aSIngo Molnar 317a5f4374aSIngo Molnar return 0; 318a5f4374aSIngo Molnar } 319a5f4374aSIngo Molnar 320a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 321a5f4374aSIngo Molnar { 322a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 323a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 324a5f4374aSIngo Molnar struct uprobe *uprobe; 325a5f4374aSIngo Molnar int match; 326a5f4374aSIngo Molnar 327a5f4374aSIngo Molnar while (n) { 328a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 329a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 330a5f4374aSIngo Molnar if (!match) { 331a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 332a5f4374aSIngo Molnar return uprobe; 333a5f4374aSIngo Molnar } 334a5f4374aSIngo Molnar 335a5f4374aSIngo Molnar if (match < 0) 336a5f4374aSIngo Molnar n = n->rb_left; 337a5f4374aSIngo Molnar else 338a5f4374aSIngo Molnar n = n->rb_right; 339a5f4374aSIngo Molnar } 340a5f4374aSIngo Molnar return NULL; 341a5f4374aSIngo Molnar } 342a5f4374aSIngo Molnar 343a5f4374aSIngo Molnar /* 344a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 345a5f4374aSIngo Molnar * Acquires uprobes_treelock 346a5f4374aSIngo Molnar */ 347a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 348a5f4374aSIngo Molnar { 349a5f4374aSIngo Molnar struct uprobe *uprobe; 350a5f4374aSIngo Molnar 3516f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 352a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 3536f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 354a5f4374aSIngo Molnar 355a5f4374aSIngo Molnar return uprobe; 356a5f4374aSIngo Molnar } 357a5f4374aSIngo Molnar 358a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 359a5f4374aSIngo Molnar { 360a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 361a5f4374aSIngo Molnar struct rb_node *parent = NULL; 362a5f4374aSIngo Molnar struct uprobe *u; 363a5f4374aSIngo Molnar int match; 364a5f4374aSIngo Molnar 365a5f4374aSIngo Molnar while (*p) { 366a5f4374aSIngo Molnar parent = *p; 367a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 368a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 369a5f4374aSIngo Molnar if (!match) { 370a5f4374aSIngo Molnar atomic_inc(&u->ref); 371a5f4374aSIngo Molnar return u; 372a5f4374aSIngo Molnar } 373a5f4374aSIngo Molnar 374a5f4374aSIngo Molnar if (match < 0) 375a5f4374aSIngo Molnar p = &parent->rb_left; 376a5f4374aSIngo Molnar else 377a5f4374aSIngo Molnar p = &parent->rb_right; 378a5f4374aSIngo Molnar 379a5f4374aSIngo Molnar } 380a5f4374aSIngo Molnar 381a5f4374aSIngo Molnar u = NULL; 382a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 383a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 384a5f4374aSIngo Molnar /* get access + creation ref */ 385a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 386a5f4374aSIngo Molnar 387a5f4374aSIngo Molnar return u; 388a5f4374aSIngo Molnar } 389a5f4374aSIngo Molnar 390a5f4374aSIngo Molnar /* 391a5f4374aSIngo Molnar * Acquire uprobes_treelock. 392a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 393a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 394a5f4374aSIngo Molnar * 395a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 396a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 397a5f4374aSIngo Molnar */ 398a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 399a5f4374aSIngo Molnar { 400a5f4374aSIngo Molnar struct uprobe *u; 401a5f4374aSIngo Molnar 4026f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 403a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 4046f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 405a5f4374aSIngo Molnar 406a5f4374aSIngo Molnar return u; 407a5f4374aSIngo Molnar } 408a5f4374aSIngo Molnar 409a5f4374aSIngo Molnar static void put_uprobe(struct uprobe *uprobe) 410a5f4374aSIngo Molnar { 411a5f4374aSIngo Molnar if (atomic_dec_and_test(&uprobe->ref)) 412a5f4374aSIngo Molnar kfree(uprobe); 413a5f4374aSIngo Molnar } 414a5f4374aSIngo Molnar 415a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 416a5f4374aSIngo Molnar { 417a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 418a5f4374aSIngo Molnar 419a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 420a5f4374aSIngo Molnar if (!uprobe) 421a5f4374aSIngo Molnar return NULL; 422a5f4374aSIngo Molnar 423a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 424a5f4374aSIngo Molnar uprobe->offset = offset; 425e591c8d7SOleg Nesterov init_rwsem(&uprobe->register_rwsem); 426a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 427bbc33d05SOleg Nesterov /* For now assume that the instruction need not be single-stepped */ 428bbc33d05SOleg Nesterov __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); 429a5f4374aSIngo Molnar 430a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 431a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 432a5f4374aSIngo Molnar 433a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 434a5f4374aSIngo Molnar if (cur_uprobe) { 435a5f4374aSIngo Molnar kfree(uprobe); 436a5f4374aSIngo Molnar uprobe = cur_uprobe; 437a5f4374aSIngo Molnar iput(inode); 438a5f4374aSIngo Molnar } 439a5f4374aSIngo Molnar 440a5f4374aSIngo Molnar return uprobe; 441a5f4374aSIngo Molnar } 442a5f4374aSIngo Molnar 4439a98e03cSOleg Nesterov static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 444a5f4374aSIngo Molnar { 445a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 446e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 447e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 448a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 449a5f4374aSIngo Molnar } 450a5f4374aSIngo Molnar 451a5f4374aSIngo Molnar /* 452e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 453e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 454a5f4374aSIngo Molnar * or return false. 455a5f4374aSIngo Molnar */ 456e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 457a5f4374aSIngo Molnar { 458a5f4374aSIngo Molnar struct uprobe_consumer **con; 459a5f4374aSIngo Molnar bool ret = false; 460a5f4374aSIngo Molnar 461a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 462a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 463e3343e6aSSrikar Dronamraju if (*con == uc) { 464e3343e6aSSrikar Dronamraju *con = uc->next; 465a5f4374aSIngo Molnar ret = true; 466a5f4374aSIngo Molnar break; 467a5f4374aSIngo Molnar } 468a5f4374aSIngo Molnar } 469a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 470a5f4374aSIngo Molnar 471a5f4374aSIngo Molnar return ret; 472a5f4374aSIngo Molnar } 473a5f4374aSIngo Molnar 474e3343e6aSSrikar Dronamraju static int 475d436615eSOleg Nesterov __copy_insn(struct address_space *mapping, struct file *filp, char *insn, 476593609a5SOleg Nesterov unsigned long nbytes, loff_t offset) 477a5f4374aSIngo Molnar { 478a5f4374aSIngo Molnar struct page *page; 479a5f4374aSIngo Molnar void *vaddr; 480593609a5SOleg Nesterov unsigned long off; 481593609a5SOleg Nesterov pgoff_t idx; 482a5f4374aSIngo Molnar 483a5f4374aSIngo Molnar if (!filp) 484a5f4374aSIngo Molnar return -EINVAL; 485a5f4374aSIngo Molnar 486cc359d18SOleg Nesterov if (!mapping->a_ops->readpage) 487cc359d18SOleg Nesterov return -EIO; 488cc359d18SOleg Nesterov 489593609a5SOleg Nesterov idx = offset >> PAGE_CACHE_SHIFT; 490593609a5SOleg Nesterov off = offset & ~PAGE_MASK; 491a5f4374aSIngo Molnar 492a5f4374aSIngo Molnar /* 493a5f4374aSIngo Molnar * Ensure that the page that has the original instruction is 494a5f4374aSIngo Molnar * populated and in page-cache. 495a5f4374aSIngo Molnar */ 496a5f4374aSIngo Molnar page = read_mapping_page(mapping, idx, filp); 497a5f4374aSIngo Molnar if (IS_ERR(page)) 498a5f4374aSIngo Molnar return PTR_ERR(page); 499a5f4374aSIngo Molnar 500a5f4374aSIngo Molnar vaddr = kmap_atomic(page); 501593609a5SOleg Nesterov memcpy(insn, vaddr + off, nbytes); 502a5f4374aSIngo Molnar kunmap_atomic(vaddr); 503a5f4374aSIngo Molnar page_cache_release(page); 504a5f4374aSIngo Molnar 505a5f4374aSIngo Molnar return 0; 506a5f4374aSIngo Molnar } 507a5f4374aSIngo Molnar 508d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 509a5f4374aSIngo Molnar { 510a5f4374aSIngo Molnar struct address_space *mapping; 511a5f4374aSIngo Molnar unsigned long nbytes; 512a5f4374aSIngo Molnar int bytes; 513a5f4374aSIngo Molnar 514d436615eSOleg Nesterov nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); 515a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 516a5f4374aSIngo Molnar 517a5f4374aSIngo Molnar /* Instruction at end of binary; copy only available bytes */ 518a5f4374aSIngo Molnar if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) 519a5f4374aSIngo Molnar bytes = uprobe->inode->i_size - uprobe->offset; 520a5f4374aSIngo Molnar else 521a5f4374aSIngo Molnar bytes = MAX_UINSN_BYTES; 522a5f4374aSIngo Molnar 523a5f4374aSIngo Molnar /* Instruction at the page-boundary; copy bytes in second page */ 524a5f4374aSIngo Molnar if (nbytes < bytes) { 525fc36f595SOleg Nesterov int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, 526fc36f595SOleg Nesterov bytes - nbytes, uprobe->offset + nbytes); 527fc36f595SOleg Nesterov if (err) 528fc36f595SOleg Nesterov return err; 529a5f4374aSIngo Molnar bytes = nbytes; 530a5f4374aSIngo Molnar } 531d436615eSOleg Nesterov return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); 532a5f4374aSIngo Molnar } 533a5f4374aSIngo Molnar 534cb9a19feSOleg Nesterov static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 535cb9a19feSOleg Nesterov struct mm_struct *mm, unsigned long vaddr) 536cb9a19feSOleg Nesterov { 537cb9a19feSOleg Nesterov int ret = 0; 538cb9a19feSOleg Nesterov 53971434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 540cb9a19feSOleg Nesterov return ret; 541cb9a19feSOleg Nesterov 542d4d3ccc6SOleg Nesterov /* TODO: move this into _register, until then we abuse this sem. */ 543d4d3ccc6SOleg Nesterov down_write(&uprobe->consumer_rwsem); 54471434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 5454710f05fSOleg Nesterov goto out; 5464710f05fSOleg Nesterov 547cb9a19feSOleg Nesterov ret = copy_insn(uprobe, file); 548cb9a19feSOleg Nesterov if (ret) 549cb9a19feSOleg Nesterov goto out; 550cb9a19feSOleg Nesterov 551cb9a19feSOleg Nesterov ret = -ENOTSUPP; 552cb9a19feSOleg Nesterov if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) 553cb9a19feSOleg Nesterov goto out; 554cb9a19feSOleg Nesterov 555cb9a19feSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 556cb9a19feSOleg Nesterov if (ret) 557cb9a19feSOleg Nesterov goto out; 558cb9a19feSOleg Nesterov 559cb9a19feSOleg Nesterov /* write_opcode() assumes we don't cross page boundary */ 560cb9a19feSOleg Nesterov BUG_ON((uprobe->offset & ~PAGE_MASK) + 561cb9a19feSOleg Nesterov UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 562cb9a19feSOleg Nesterov 563cb9a19feSOleg Nesterov smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ 56471434f2fSOleg Nesterov set_bit(UPROBE_COPY_INSN, &uprobe->flags); 565cb9a19feSOleg Nesterov 566cb9a19feSOleg Nesterov out: 567d4d3ccc6SOleg Nesterov up_write(&uprobe->consumer_rwsem); 5684710f05fSOleg Nesterov 569cb9a19feSOleg Nesterov return ret; 570cb9a19feSOleg Nesterov } 571cb9a19feSOleg Nesterov 5728a7f2fa0SOleg Nesterov static inline bool consumer_filter(struct uprobe_consumer *uc, 5738a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 574806a98bdSOleg Nesterov { 5758a7f2fa0SOleg Nesterov return !uc->filter || uc->filter(uc, ctx, mm); 576806a98bdSOleg Nesterov } 577806a98bdSOleg Nesterov 5788a7f2fa0SOleg Nesterov static bool filter_chain(struct uprobe *uprobe, 5798a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 58063633cbfSOleg Nesterov { 5811ff6fee5SOleg Nesterov struct uprobe_consumer *uc; 5821ff6fee5SOleg Nesterov bool ret = false; 5831ff6fee5SOleg Nesterov 5841ff6fee5SOleg Nesterov down_read(&uprobe->consumer_rwsem); 5851ff6fee5SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 5868a7f2fa0SOleg Nesterov ret = consumer_filter(uc, ctx, mm); 5871ff6fee5SOleg Nesterov if (ret) 5881ff6fee5SOleg Nesterov break; 5891ff6fee5SOleg Nesterov } 5901ff6fee5SOleg Nesterov up_read(&uprobe->consumer_rwsem); 5911ff6fee5SOleg Nesterov 5921ff6fee5SOleg Nesterov return ret; 59363633cbfSOleg Nesterov } 59463633cbfSOleg Nesterov 595e3343e6aSSrikar Dronamraju static int 596e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 597816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 598a5f4374aSIngo Molnar { 599f8ac4ec9SOleg Nesterov bool first_uprobe; 600a5f4374aSIngo Molnar int ret; 601a5f4374aSIngo Molnar 602cb9a19feSOleg Nesterov ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); 603a5f4374aSIngo Molnar if (ret) 604a5f4374aSIngo Molnar return ret; 605a5f4374aSIngo Molnar 606f8ac4ec9SOleg Nesterov /* 607f8ac4ec9SOleg Nesterov * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), 608f8ac4ec9SOleg Nesterov * the task can hit this breakpoint right after __replace_page(). 609f8ac4ec9SOleg Nesterov */ 610f8ac4ec9SOleg Nesterov first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); 611f8ac4ec9SOleg Nesterov if (first_uprobe) 612f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &mm->flags); 613f8ac4ec9SOleg Nesterov 614816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 6159f68f672SOleg Nesterov if (!ret) 6169f68f672SOleg Nesterov clear_bit(MMF_RECALC_UPROBES, &mm->flags); 6179f68f672SOleg Nesterov else if (first_uprobe) 618f8ac4ec9SOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 619a5f4374aSIngo Molnar 620a5f4374aSIngo Molnar return ret; 621a5f4374aSIngo Molnar } 622a5f4374aSIngo Molnar 623076a365bSOleg Nesterov static int 624816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 625a5f4374aSIngo Molnar { 6269f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &mm->flags); 627076a365bSOleg Nesterov return set_orig_insn(&uprobe->arch, mm, vaddr); 628a5f4374aSIngo Molnar } 629a5f4374aSIngo Molnar 63006b7bcd8SOleg Nesterov static inline bool uprobe_is_active(struct uprobe *uprobe) 63106b7bcd8SOleg Nesterov { 63206b7bcd8SOleg Nesterov return !RB_EMPTY_NODE(&uprobe->rb_node); 63306b7bcd8SOleg Nesterov } 6340326f5a9SSrikar Dronamraju /* 635778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 636778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 637778b032dSOleg Nesterov * See find_active_uprobe(). 6380326f5a9SSrikar Dronamraju */ 639a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 640a5f4374aSIngo Molnar { 64106b7bcd8SOleg Nesterov if (WARN_ON(!uprobe_is_active(uprobe))) 64206b7bcd8SOleg Nesterov return; 64306b7bcd8SOleg Nesterov 6446f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 645a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 6466f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 64706b7bcd8SOleg Nesterov RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ 648a5f4374aSIngo Molnar iput(uprobe->inode); 649a5f4374aSIngo Molnar put_uprobe(uprobe); 650a5f4374aSIngo Molnar } 651a5f4374aSIngo Molnar 65226872090SOleg Nesterov struct map_info { 65326872090SOleg Nesterov struct map_info *next; 65426872090SOleg Nesterov struct mm_struct *mm; 655816c03fbSOleg Nesterov unsigned long vaddr; 65626872090SOleg Nesterov }; 65726872090SOleg Nesterov 65826872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 659a5f4374aSIngo Molnar { 66026872090SOleg Nesterov struct map_info *next = info->next; 66126872090SOleg Nesterov kfree(info); 66226872090SOleg Nesterov return next; 66326872090SOleg Nesterov } 66426872090SOleg Nesterov 66526872090SOleg Nesterov static struct map_info * 66626872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 66726872090SOleg Nesterov { 66826872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 669a5f4374aSIngo Molnar struct vm_area_struct *vma; 67026872090SOleg Nesterov struct map_info *curr = NULL; 67126872090SOleg Nesterov struct map_info *prev = NULL; 67226872090SOleg Nesterov struct map_info *info; 67326872090SOleg Nesterov int more = 0; 674a5f4374aSIngo Molnar 67526872090SOleg Nesterov again: 67626872090SOleg Nesterov mutex_lock(&mapping->i_mmap_mutex); 6776b2dbba8SMichel Lespinasse vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { 678a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 679a5f4374aSIngo Molnar continue; 680a5f4374aSIngo Molnar 6817a5bfb66SOleg Nesterov if (!prev && !more) { 6827a5bfb66SOleg Nesterov /* 6837a5bfb66SOleg Nesterov * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through 6847a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 6857a5bfb66SOleg Nesterov */ 6867a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 6877a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 6887a5bfb66SOleg Nesterov if (prev) 6897a5bfb66SOleg Nesterov prev->next = NULL; 6907a5bfb66SOleg Nesterov } 69126872090SOleg Nesterov if (!prev) { 69226872090SOleg Nesterov more++; 69326872090SOleg Nesterov continue; 694a5f4374aSIngo Molnar } 695a5f4374aSIngo Molnar 69626872090SOleg Nesterov if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) 69726872090SOleg Nesterov continue; 698a5f4374aSIngo Molnar 69926872090SOleg Nesterov info = prev; 70026872090SOleg Nesterov prev = prev->next; 70126872090SOleg Nesterov info->next = curr; 70226872090SOleg Nesterov curr = info; 70326872090SOleg Nesterov 70426872090SOleg Nesterov info->mm = vma->vm_mm; 70557683f72SOleg Nesterov info->vaddr = offset_to_vaddr(vma, offset); 706a5f4374aSIngo Molnar } 707a5f4374aSIngo Molnar mutex_unlock(&mapping->i_mmap_mutex); 708a5f4374aSIngo Molnar 70926872090SOleg Nesterov if (!more) 71026872090SOleg Nesterov goto out; 711a5f4374aSIngo Molnar 71226872090SOleg Nesterov prev = curr; 71326872090SOleg Nesterov while (curr) { 71426872090SOleg Nesterov mmput(curr->mm); 71526872090SOleg Nesterov curr = curr->next; 71626872090SOleg Nesterov } 71726872090SOleg Nesterov 71826872090SOleg Nesterov do { 71926872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 72026872090SOleg Nesterov if (!info) { 72126872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 72226872090SOleg Nesterov goto out; 72326872090SOleg Nesterov } 72426872090SOleg Nesterov info->next = prev; 72526872090SOleg Nesterov prev = info; 72626872090SOleg Nesterov } while (--more); 72726872090SOleg Nesterov 72826872090SOleg Nesterov goto again; 72926872090SOleg Nesterov out: 73026872090SOleg Nesterov while (prev) 73126872090SOleg Nesterov prev = free_map_info(prev); 73226872090SOleg Nesterov return curr; 733a5f4374aSIngo Molnar } 734a5f4374aSIngo Molnar 735a5f4374aSIngo Molnar static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 736a5f4374aSIngo Molnar { 73726872090SOleg Nesterov struct map_info *info; 73826872090SOleg Nesterov int err = 0; 73926872090SOleg Nesterov 74032cdba1eSOleg Nesterov percpu_down_write(&dup_mmap_sem); 74126872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 74226872090SOleg Nesterov uprobe->offset, is_register); 74332cdba1eSOleg Nesterov if (IS_ERR(info)) { 74432cdba1eSOleg Nesterov err = PTR_ERR(info); 74532cdba1eSOleg Nesterov goto out; 74632cdba1eSOleg Nesterov } 74726872090SOleg Nesterov 74826872090SOleg Nesterov while (info) { 74926872090SOleg Nesterov struct mm_struct *mm = info->mm; 750a5f4374aSIngo Molnar struct vm_area_struct *vma; 751a5f4374aSIngo Molnar 752076a365bSOleg Nesterov if (err && is_register) 75326872090SOleg Nesterov goto free; 754a5f4374aSIngo Molnar 75577fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 756f4d6dfe5SOleg Nesterov vma = find_vma(mm, info->vaddr); 757f4d6dfe5SOleg Nesterov if (!vma || !valid_vma(vma, is_register) || 758f4d6dfe5SOleg Nesterov vma->vm_file->f_mapping->host != uprobe->inode) 75926872090SOleg Nesterov goto unlock; 76026872090SOleg Nesterov 761f4d6dfe5SOleg Nesterov if (vma->vm_start > info->vaddr || 762f4d6dfe5SOleg Nesterov vaddr_to_offset(vma, info->vaddr) != uprobe->offset) 76326872090SOleg Nesterov goto unlock; 764a5f4374aSIngo Molnar 765806a98bdSOleg Nesterov if (is_register) { 766806a98bdSOleg Nesterov /* consult only the "caller", new consumer. */ 7678a7f2fa0SOleg Nesterov if (consumer_filter(uprobe->consumers, 7688a7f2fa0SOleg Nesterov UPROBE_FILTER_REGISTER, mm)) 76926872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 770806a98bdSOleg Nesterov } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { 7718a7f2fa0SOleg Nesterov if (!filter_chain(uprobe, 7728a7f2fa0SOleg Nesterov UPROBE_FILTER_UNREGISTER, mm)) 773076a365bSOleg Nesterov err |= remove_breakpoint(uprobe, mm, info->vaddr); 774806a98bdSOleg Nesterov } 77578f74116SOleg Nesterov 77626872090SOleg Nesterov unlock: 77726872090SOleg Nesterov up_write(&mm->mmap_sem); 77826872090SOleg Nesterov free: 77926872090SOleg Nesterov mmput(mm); 78026872090SOleg Nesterov info = free_map_info(info); 781a5f4374aSIngo Molnar } 78232cdba1eSOleg Nesterov out: 78332cdba1eSOleg Nesterov percpu_up_write(&dup_mmap_sem); 78426872090SOleg Nesterov return err; 785a5f4374aSIngo Molnar } 786a5f4374aSIngo Molnar 7879a98e03cSOleg Nesterov static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) 788a5f4374aSIngo Molnar { 7899a98e03cSOleg Nesterov consumer_add(uprobe, uc); 790bb929284SOleg Nesterov return register_for_each_vma(uprobe, true); 791a5f4374aSIngo Molnar } 792a5f4374aSIngo Molnar 79304aab9b2SOleg Nesterov static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) 794a5f4374aSIngo Molnar { 79504aab9b2SOleg Nesterov int err; 796a5f4374aSIngo Molnar 79704aab9b2SOleg Nesterov if (!consumer_del(uprobe, uc)) /* WARN? */ 79804aab9b2SOleg Nesterov return; 79904aab9b2SOleg Nesterov 80004aab9b2SOleg Nesterov err = register_for_each_vma(uprobe, false); 801a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 802bb929284SOleg Nesterov if (!uprobe->consumers && !err) 80304aab9b2SOleg Nesterov delete_uprobe(uprobe); 80404aab9b2SOleg Nesterov } 805a5f4374aSIngo Molnar 806a5f4374aSIngo Molnar /* 807a5f4374aSIngo Molnar * uprobe_register - register a probe 808a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 809a5f4374aSIngo Molnar * @offset: offset from the start of the file. 810e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 811a5f4374aSIngo Molnar * 812a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 813a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 814a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 815a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 816a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 817e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 818a5f4374aSIngo Molnar * unregisters. 819a5f4374aSIngo Molnar * 820a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 821a5f4374aSIngo Molnar * else return 0 (success) 822a5f4374aSIngo Molnar */ 823e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 824a5f4374aSIngo Molnar { 825a5f4374aSIngo Molnar struct uprobe *uprobe; 826a5f4374aSIngo Molnar int ret; 827a5f4374aSIngo Molnar 828f0744af7SOleg Nesterov /* Racy, just to catch the obvious mistakes */ 829a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 830a5f4374aSIngo Molnar return -EINVAL; 831a5f4374aSIngo Molnar 83266d06dffSOleg Nesterov retry: 833a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 83466d06dffSOleg Nesterov if (!uprobe) 83566d06dffSOleg Nesterov return -ENOMEM; 83666d06dffSOleg Nesterov /* 83766d06dffSOleg Nesterov * We can race with uprobe_unregister()->delete_uprobe(). 83866d06dffSOleg Nesterov * Check uprobe_is_active() and retry if it is false. 83966d06dffSOleg Nesterov */ 840e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 84166d06dffSOleg Nesterov ret = -EAGAIN; 84266d06dffSOleg Nesterov if (likely(uprobe_is_active(uprobe))) { 8439a98e03cSOleg Nesterov ret = __uprobe_register(uprobe, uc); 8449a98e03cSOleg Nesterov if (ret) 84504aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 846a5f4374aSIngo Molnar } 84766d06dffSOleg Nesterov up_write(&uprobe->register_rwsem); 848a5f4374aSIngo Molnar put_uprobe(uprobe); 849a5f4374aSIngo Molnar 85066d06dffSOleg Nesterov if (unlikely(ret == -EAGAIN)) 85166d06dffSOleg Nesterov goto retry; 852a5f4374aSIngo Molnar return ret; 853a5f4374aSIngo Molnar } 854a5f4374aSIngo Molnar 855a5f4374aSIngo Molnar /* 856a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 857a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 858a5f4374aSIngo Molnar * @offset: offset from the start of the file. 859e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 860a5f4374aSIngo Molnar */ 861e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 862a5f4374aSIngo Molnar { 863a5f4374aSIngo Molnar struct uprobe *uprobe; 864a5f4374aSIngo Molnar 865a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 866a5f4374aSIngo Molnar if (!uprobe) 867a5f4374aSIngo Molnar return; 868a5f4374aSIngo Molnar 869e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 87004aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 871e591c8d7SOleg Nesterov up_write(&uprobe->register_rwsem); 872a5f4374aSIngo Molnar put_uprobe(uprobe); 873a5f4374aSIngo Molnar } 874a5f4374aSIngo Molnar 875da1816b1SOleg Nesterov static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) 876da1816b1SOleg Nesterov { 877da1816b1SOleg Nesterov struct vm_area_struct *vma; 878da1816b1SOleg Nesterov int err = 0; 879da1816b1SOleg Nesterov 880da1816b1SOleg Nesterov down_read(&mm->mmap_sem); 881da1816b1SOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 882da1816b1SOleg Nesterov unsigned long vaddr; 883da1816b1SOleg Nesterov loff_t offset; 884da1816b1SOleg Nesterov 885da1816b1SOleg Nesterov if (!valid_vma(vma, false) || 886da1816b1SOleg Nesterov vma->vm_file->f_mapping->host != uprobe->inode) 887da1816b1SOleg Nesterov continue; 888da1816b1SOleg Nesterov 889da1816b1SOleg Nesterov offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; 890da1816b1SOleg Nesterov if (uprobe->offset < offset || 891da1816b1SOleg Nesterov uprobe->offset >= offset + vma->vm_end - vma->vm_start) 892da1816b1SOleg Nesterov continue; 893da1816b1SOleg Nesterov 894da1816b1SOleg Nesterov vaddr = offset_to_vaddr(vma, uprobe->offset); 895da1816b1SOleg Nesterov err |= remove_breakpoint(uprobe, mm, vaddr); 896da1816b1SOleg Nesterov } 897da1816b1SOleg Nesterov up_read(&mm->mmap_sem); 898da1816b1SOleg Nesterov 899da1816b1SOleg Nesterov return err; 900da1816b1SOleg Nesterov } 901da1816b1SOleg Nesterov 902891c3970SOleg Nesterov static struct rb_node * 903891c3970SOleg Nesterov find_node_in_range(struct inode *inode, loff_t min, loff_t max) 904a5f4374aSIngo Molnar { 905a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 906a5f4374aSIngo Molnar 907a5f4374aSIngo Molnar while (n) { 908891c3970SOleg Nesterov struct uprobe *u = rb_entry(n, struct uprobe, rb_node); 909a5f4374aSIngo Molnar 910891c3970SOleg Nesterov if (inode < u->inode) { 911a5f4374aSIngo Molnar n = n->rb_left; 912891c3970SOleg Nesterov } else if (inode > u->inode) { 913a5f4374aSIngo Molnar n = n->rb_right; 914891c3970SOleg Nesterov } else { 915891c3970SOleg Nesterov if (max < u->offset) 916891c3970SOleg Nesterov n = n->rb_left; 917891c3970SOleg Nesterov else if (min > u->offset) 918891c3970SOleg Nesterov n = n->rb_right; 919891c3970SOleg Nesterov else 920891c3970SOleg Nesterov break; 921891c3970SOleg Nesterov } 922a5f4374aSIngo Molnar } 923a5f4374aSIngo Molnar 924891c3970SOleg Nesterov return n; 925a5f4374aSIngo Molnar } 926a5f4374aSIngo Molnar 927a5f4374aSIngo Molnar /* 928891c3970SOleg Nesterov * For a given range in vma, build a list of probes that need to be inserted. 929a5f4374aSIngo Molnar */ 930891c3970SOleg Nesterov static void build_probe_list(struct inode *inode, 931891c3970SOleg Nesterov struct vm_area_struct *vma, 932891c3970SOleg Nesterov unsigned long start, unsigned long end, 933891c3970SOleg Nesterov struct list_head *head) 934a5f4374aSIngo Molnar { 935891c3970SOleg Nesterov loff_t min, max; 936891c3970SOleg Nesterov struct rb_node *n, *t; 937891c3970SOleg Nesterov struct uprobe *u; 938891c3970SOleg Nesterov 939891c3970SOleg Nesterov INIT_LIST_HEAD(head); 940cb113b47SOleg Nesterov min = vaddr_to_offset(vma, start); 941891c3970SOleg Nesterov max = min + (end - start) - 1; 942a5f4374aSIngo Molnar 9436f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 944891c3970SOleg Nesterov n = find_node_in_range(inode, min, max); 945891c3970SOleg Nesterov if (n) { 946891c3970SOleg Nesterov for (t = n; t; t = rb_prev(t)) { 947891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 948891c3970SOleg Nesterov if (u->inode != inode || u->offset < min) 949a5f4374aSIngo Molnar break; 950891c3970SOleg Nesterov list_add(&u->pending_list, head); 951891c3970SOleg Nesterov atomic_inc(&u->ref); 952a5f4374aSIngo Molnar } 953891c3970SOleg Nesterov for (t = n; (t = rb_next(t)); ) { 954891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 955891c3970SOleg Nesterov if (u->inode != inode || u->offset > max) 956891c3970SOleg Nesterov break; 957891c3970SOleg Nesterov list_add(&u->pending_list, head); 958891c3970SOleg Nesterov atomic_inc(&u->ref); 959891c3970SOleg Nesterov } 960891c3970SOleg Nesterov } 9616f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 962a5f4374aSIngo Molnar } 963a5f4374aSIngo Molnar 964a5f4374aSIngo Molnar /* 9655e5be71aSOleg Nesterov * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. 966a5f4374aSIngo Molnar * 9675e5be71aSOleg Nesterov * Currently we ignore all errors and always return 0, the callers 9685e5be71aSOleg Nesterov * can't handle the failure anyway. 969a5f4374aSIngo Molnar */ 970a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 971a5f4374aSIngo Molnar { 972a5f4374aSIngo Molnar struct list_head tmp_list; 973665605a2SOleg Nesterov struct uprobe *uprobe, *u; 974a5f4374aSIngo Molnar struct inode *inode; 975a5f4374aSIngo Molnar 976441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, true)) 977a5f4374aSIngo Molnar return 0; 978a5f4374aSIngo Molnar 979a5f4374aSIngo Molnar inode = vma->vm_file->f_mapping->host; 980a5f4374aSIngo Molnar if (!inode) 981a5f4374aSIngo Molnar return 0; 982a5f4374aSIngo Molnar 983a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 984891c3970SOleg Nesterov build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); 985806a98bdSOleg Nesterov /* 986806a98bdSOleg Nesterov * We can race with uprobe_unregister(), this uprobe can be already 987806a98bdSOleg Nesterov * removed. But in this case filter_chain() must return false, all 988806a98bdSOleg Nesterov * consumers have gone away. 989806a98bdSOleg Nesterov */ 990665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 991806a98bdSOleg Nesterov if (!fatal_signal_pending(current) && 9928a7f2fa0SOleg Nesterov filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { 99357683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 9945e5be71aSOleg Nesterov install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 995a5f4374aSIngo Molnar } 996a5f4374aSIngo Molnar put_uprobe(uprobe); 997a5f4374aSIngo Molnar } 998a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 999a5f4374aSIngo Molnar 10005e5be71aSOleg Nesterov return 0; 1001a5f4374aSIngo Molnar } 1002a5f4374aSIngo Molnar 10039f68f672SOleg Nesterov static bool 10049f68f672SOleg Nesterov vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) 10059f68f672SOleg Nesterov { 10069f68f672SOleg Nesterov loff_t min, max; 10079f68f672SOleg Nesterov struct inode *inode; 10089f68f672SOleg Nesterov struct rb_node *n; 10099f68f672SOleg Nesterov 10109f68f672SOleg Nesterov inode = vma->vm_file->f_mapping->host; 10119f68f672SOleg Nesterov 10129f68f672SOleg Nesterov min = vaddr_to_offset(vma, start); 10139f68f672SOleg Nesterov max = min + (end - start) - 1; 10149f68f672SOleg Nesterov 10159f68f672SOleg Nesterov spin_lock(&uprobes_treelock); 10169f68f672SOleg Nesterov n = find_node_in_range(inode, min, max); 10179f68f672SOleg Nesterov spin_unlock(&uprobes_treelock); 10189f68f672SOleg Nesterov 10199f68f672SOleg Nesterov return !!n; 10209f68f672SOleg Nesterov } 10219f68f672SOleg Nesterov 1022682968e0SSrikar Dronamraju /* 1023682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1024682968e0SSrikar Dronamraju */ 1025cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1026682968e0SSrikar Dronamraju { 1027441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, false)) 1028682968e0SSrikar Dronamraju return; 1029682968e0SSrikar Dronamraju 10302fd611a9SOleg Nesterov if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ 10312fd611a9SOleg Nesterov return; 10322fd611a9SOleg Nesterov 10339f68f672SOleg Nesterov if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || 10349f68f672SOleg Nesterov test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) 1035f8ac4ec9SOleg Nesterov return; 1036f8ac4ec9SOleg Nesterov 10379f68f672SOleg Nesterov if (vma_has_uprobes(vma, start, end)) 10389f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); 1039682968e0SSrikar Dronamraju } 1040682968e0SSrikar Dronamraju 1041d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 1042d4b3b638SSrikar Dronamraju static int xol_add_vma(struct xol_area *area) 1043d4b3b638SSrikar Dronamraju { 1044c8a82538SOleg Nesterov struct mm_struct *mm = current->mm; 1045c8a82538SOleg Nesterov int ret = -EALREADY; 1046d4b3b638SSrikar Dronamraju 1047d4b3b638SSrikar Dronamraju down_write(&mm->mmap_sem); 1048d4b3b638SSrikar Dronamraju if (mm->uprobes_state.xol_area) 1049d4b3b638SSrikar Dronamraju goto fail; 1050d4b3b638SSrikar Dronamraju 1051d4b3b638SSrikar Dronamraju ret = -ENOMEM; 1052d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1053d4b3b638SSrikar Dronamraju area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); 1054d4b3b638SSrikar Dronamraju if (area->vaddr & ~PAGE_MASK) { 1055d4b3b638SSrikar Dronamraju ret = area->vaddr; 1056d4b3b638SSrikar Dronamraju goto fail; 1057d4b3b638SSrikar Dronamraju } 1058d4b3b638SSrikar Dronamraju 1059d4b3b638SSrikar Dronamraju ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1060d4b3b638SSrikar Dronamraju VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); 1061d4b3b638SSrikar Dronamraju if (ret) 1062d4b3b638SSrikar Dronamraju goto fail; 1063d4b3b638SSrikar Dronamraju 1064d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1065d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1066d4b3b638SSrikar Dronamraju ret = 0; 1067d4b3b638SSrikar Dronamraju fail: 1068d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1069d4b3b638SSrikar Dronamraju 1070d4b3b638SSrikar Dronamraju return ret; 1071d4b3b638SSrikar Dronamraju } 1072d4b3b638SSrikar Dronamraju 1073d4b3b638SSrikar Dronamraju /* 10749b545df8SOleg Nesterov * get_xol_area - Allocate process's xol_area if necessary. 10759b545df8SOleg Nesterov * This area will be used for storing instructions for execution out of line. 1076d4b3b638SSrikar Dronamraju * 1077d4b3b638SSrikar Dronamraju * Returns the allocated area or NULL. 1078d4b3b638SSrikar Dronamraju */ 10799b545df8SOleg Nesterov static struct xol_area *get_xol_area(void) 1080d4b3b638SSrikar Dronamraju { 10819b545df8SOleg Nesterov struct mm_struct *mm = current->mm; 1082d4b3b638SSrikar Dronamraju struct xol_area *area; 1083d4b3b638SSrikar Dronamraju 10849b545df8SOleg Nesterov area = mm->uprobes_state.xol_area; 10859b545df8SOleg Nesterov if (area) 10869b545df8SOleg Nesterov goto ret; 10879b545df8SOleg Nesterov 1088d4b3b638SSrikar Dronamraju area = kzalloc(sizeof(*area), GFP_KERNEL); 1089d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1090c8a82538SOleg Nesterov goto out; 1091d4b3b638SSrikar Dronamraju 1092d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1093d4b3b638SSrikar Dronamraju if (!area->bitmap) 1094c8a82538SOleg Nesterov goto free_area; 1095c8a82538SOleg Nesterov 1096c8a82538SOleg Nesterov area->page = alloc_page(GFP_HIGHUSER); 1097c8a82538SOleg Nesterov if (!area->page) 1098c8a82538SOleg Nesterov goto free_bitmap; 1099d4b3b638SSrikar Dronamraju 1100d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 1101d4b3b638SSrikar Dronamraju if (!xol_add_vma(area)) 1102d4b3b638SSrikar Dronamraju return area; 1103d4b3b638SSrikar Dronamraju 1104c8a82538SOleg Nesterov __free_page(area->page); 1105c8a82538SOleg Nesterov free_bitmap: 1106d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1107c8a82538SOleg Nesterov free_area: 1108d4b3b638SSrikar Dronamraju kfree(area); 1109c8a82538SOleg Nesterov out: 11109b545df8SOleg Nesterov area = mm->uprobes_state.xol_area; 11119b545df8SOleg Nesterov ret: 11129b545df8SOleg Nesterov smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 11139b545df8SOleg Nesterov return area; 1114d4b3b638SSrikar Dronamraju } 1115d4b3b638SSrikar Dronamraju 1116d4b3b638SSrikar Dronamraju /* 1117d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1118d4b3b638SSrikar Dronamraju */ 1119d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1120d4b3b638SSrikar Dronamraju { 1121d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1122d4b3b638SSrikar Dronamraju 1123d4b3b638SSrikar Dronamraju if (!area) 1124d4b3b638SSrikar Dronamraju return; 1125d4b3b638SSrikar Dronamraju 1126d4b3b638SSrikar Dronamraju put_page(area->page); 1127d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1128d4b3b638SSrikar Dronamraju kfree(area); 1129d4b3b638SSrikar Dronamraju } 1130d4b3b638SSrikar Dronamraju 113132cdba1eSOleg Nesterov void uprobe_start_dup_mmap(void) 113232cdba1eSOleg Nesterov { 113332cdba1eSOleg Nesterov percpu_down_read(&dup_mmap_sem); 113432cdba1eSOleg Nesterov } 113532cdba1eSOleg Nesterov 113632cdba1eSOleg Nesterov void uprobe_end_dup_mmap(void) 113732cdba1eSOleg Nesterov { 113832cdba1eSOleg Nesterov percpu_up_read(&dup_mmap_sem); 113932cdba1eSOleg Nesterov } 114032cdba1eSOleg Nesterov 1141f8ac4ec9SOleg Nesterov void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) 1142f8ac4ec9SOleg Nesterov { 114361559a81SOleg Nesterov newmm->uprobes_state.xol_area = NULL; 114461559a81SOleg Nesterov 11459f68f672SOleg Nesterov if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { 1146f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &newmm->flags); 11479f68f672SOleg Nesterov /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ 11489f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &newmm->flags); 11499f68f672SOleg Nesterov } 1150f8ac4ec9SOleg Nesterov } 1151f8ac4ec9SOleg Nesterov 1152d4b3b638SSrikar Dronamraju /* 1153d4b3b638SSrikar Dronamraju * - search for a free slot. 1154d4b3b638SSrikar Dronamraju */ 1155d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1156d4b3b638SSrikar Dronamraju { 1157d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1158d4b3b638SSrikar Dronamraju int slot_nr; 1159d4b3b638SSrikar Dronamraju 1160d4b3b638SSrikar Dronamraju do { 1161d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1162d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1163d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1164d4b3b638SSrikar Dronamraju break; 1165d4b3b638SSrikar Dronamraju 1166d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1167d4b3b638SSrikar Dronamraju continue; 1168d4b3b638SSrikar Dronamraju } 1169d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1170d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1171d4b3b638SSrikar Dronamraju 1172d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1173d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1174d4b3b638SSrikar Dronamraju 1175d4b3b638SSrikar Dronamraju return slot_addr; 1176d4b3b638SSrikar Dronamraju } 1177d4b3b638SSrikar Dronamraju 1178d4b3b638SSrikar Dronamraju /* 1179a6cb3f6dSOleg Nesterov * xol_get_insn_slot - allocate a slot for xol. 1180d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1181d4b3b638SSrikar Dronamraju */ 1182a6cb3f6dSOleg Nesterov static unsigned long xol_get_insn_slot(struct uprobe *uprobe) 1183d4b3b638SSrikar Dronamraju { 1184d4b3b638SSrikar Dronamraju struct xol_area *area; 1185d4b3b638SSrikar Dronamraju unsigned long offset; 1186a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1187d4b3b638SSrikar Dronamraju void *vaddr; 1188d4b3b638SSrikar Dronamraju 11899b545df8SOleg Nesterov area = get_xol_area(); 1190d4b3b638SSrikar Dronamraju if (!area) 1191d4b3b638SSrikar Dronamraju return 0; 1192d4b3b638SSrikar Dronamraju 1193a6cb3f6dSOleg Nesterov xol_vaddr = xol_take_insn_slot(area); 1194a6cb3f6dSOleg Nesterov if (unlikely(!xol_vaddr)) 1195d4b3b638SSrikar Dronamraju return 0; 1196d4b3b638SSrikar Dronamraju 1197a6cb3f6dSOleg Nesterov /* Initialize the slot */ 1198a6cb3f6dSOleg Nesterov offset = xol_vaddr & ~PAGE_MASK; 1199d4b3b638SSrikar Dronamraju vaddr = kmap_atomic(area->page); 1200d4b3b638SSrikar Dronamraju memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); 1201d4b3b638SSrikar Dronamraju kunmap_atomic(vaddr); 120265b6ecc0SRabin Vincent /* 120365b6ecc0SRabin Vincent * We probably need flush_icache_user_range() but it needs vma. 120465b6ecc0SRabin Vincent * This should work on supported architectures too. 120565b6ecc0SRabin Vincent */ 120665b6ecc0SRabin Vincent flush_dcache_page(area->page); 1207d4b3b638SSrikar Dronamraju 1208a6cb3f6dSOleg Nesterov return xol_vaddr; 1209d4b3b638SSrikar Dronamraju } 1210d4b3b638SSrikar Dronamraju 1211d4b3b638SSrikar Dronamraju /* 1212d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1213d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1214d4b3b638SSrikar Dronamraju * subsequent requests. 1215d4b3b638SSrikar Dronamraju */ 1216d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1217d4b3b638SSrikar Dronamraju { 1218d4b3b638SSrikar Dronamraju struct xol_area *area; 1219d4b3b638SSrikar Dronamraju unsigned long vma_end; 1220d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1221d4b3b638SSrikar Dronamraju 1222d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1223d4b3b638SSrikar Dronamraju return; 1224d4b3b638SSrikar Dronamraju 1225d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1226d4b3b638SSrikar Dronamraju 1227d4b3b638SSrikar Dronamraju if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) 1228d4b3b638SSrikar Dronamraju return; 1229d4b3b638SSrikar Dronamraju 1230d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1231d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1232d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1233d4b3b638SSrikar Dronamraju unsigned long offset; 1234d4b3b638SSrikar Dronamraju int slot_nr; 1235d4b3b638SSrikar Dronamraju 1236d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1237d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1238d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1239d4b3b638SSrikar Dronamraju return; 1240d4b3b638SSrikar Dronamraju 1241d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1242d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 1243d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1244d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1245d4b3b638SSrikar Dronamraju 1246d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1247d4b3b638SSrikar Dronamraju } 1248d4b3b638SSrikar Dronamraju } 1249d4b3b638SSrikar Dronamraju 12500326f5a9SSrikar Dronamraju /** 12510326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 12520326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 12530326f5a9SSrikar Dronamraju * instruction. 12540326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 12550326f5a9SSrikar Dronamraju */ 12560326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 12570326f5a9SSrikar Dronamraju { 12580326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 12590326f5a9SSrikar Dronamraju } 12600326f5a9SSrikar Dronamraju 12610326f5a9SSrikar Dronamraju /* 12620326f5a9SSrikar Dronamraju * Called with no locks held. 12630326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 12640326f5a9SSrikar Dronamraju */ 12650326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 12660326f5a9SSrikar Dronamraju { 12670326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 12680326f5a9SSrikar Dronamraju 12690326f5a9SSrikar Dronamraju if (!utask) 12700326f5a9SSrikar Dronamraju return; 12710326f5a9SSrikar Dronamraju 12720326f5a9SSrikar Dronamraju if (utask->active_uprobe) 12730326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 12740326f5a9SSrikar Dronamraju 1275d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 12760326f5a9SSrikar Dronamraju kfree(utask); 12770326f5a9SSrikar Dronamraju t->utask = NULL; 12780326f5a9SSrikar Dronamraju } 12790326f5a9SSrikar Dronamraju 12800326f5a9SSrikar Dronamraju /* 12810326f5a9SSrikar Dronamraju * Called in context of a new clone/fork from copy_process. 12820326f5a9SSrikar Dronamraju */ 12830326f5a9SSrikar Dronamraju void uprobe_copy_process(struct task_struct *t) 12840326f5a9SSrikar Dronamraju { 12850326f5a9SSrikar Dronamraju t->utask = NULL; 12860326f5a9SSrikar Dronamraju } 12870326f5a9SSrikar Dronamraju 12880326f5a9SSrikar Dronamraju /* 12895a2df662SOleg Nesterov * Allocate a uprobe_task object for the task if if necessary. 12905a2df662SOleg Nesterov * Called when the thread hits a breakpoint. 12910326f5a9SSrikar Dronamraju * 12920326f5a9SSrikar Dronamraju * Returns: 12930326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 12940326f5a9SSrikar Dronamraju * - NULL otherwise 12950326f5a9SSrikar Dronamraju */ 12965a2df662SOleg Nesterov static struct uprobe_task *get_utask(void) 12970326f5a9SSrikar Dronamraju { 12985a2df662SOleg Nesterov if (!current->utask) 12995a2df662SOleg Nesterov current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 13005a2df662SOleg Nesterov return current->utask; 13010326f5a9SSrikar Dronamraju } 13020326f5a9SSrikar Dronamraju 13030326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 13040326f5a9SSrikar Dronamraju static int 1305a6cb3f6dSOleg Nesterov pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) 13060326f5a9SSrikar Dronamraju { 1307a6cb3f6dSOleg Nesterov struct uprobe_task *utask; 1308a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1309aba51024SOleg Nesterov int err; 1310d4b3b638SSrikar Dronamraju 1311*608e7427SOleg Nesterov utask = get_utask(); 1312*608e7427SOleg Nesterov if (!utask) 1313*608e7427SOleg Nesterov return -ENOMEM; 1314a6cb3f6dSOleg Nesterov 1315a6cb3f6dSOleg Nesterov xol_vaddr = xol_get_insn_slot(uprobe); 1316a6cb3f6dSOleg Nesterov if (!xol_vaddr) 1317a6cb3f6dSOleg Nesterov return -ENOMEM; 1318a6cb3f6dSOleg Nesterov 1319a6cb3f6dSOleg Nesterov utask->xol_vaddr = xol_vaddr; 1320a6cb3f6dSOleg Nesterov utask->vaddr = bp_vaddr; 1321a6cb3f6dSOleg Nesterov 1322aba51024SOleg Nesterov err = arch_uprobe_pre_xol(&uprobe->arch, regs); 1323aba51024SOleg Nesterov if (unlikely(err)) { 1324aba51024SOleg Nesterov xol_free_insn_slot(current); 1325aba51024SOleg Nesterov return err; 1326aba51024SOleg Nesterov } 1327aba51024SOleg Nesterov 1328*608e7427SOleg Nesterov utask->active_uprobe = uprobe; 1329*608e7427SOleg Nesterov utask->state = UTASK_SSTEP; 1330aba51024SOleg Nesterov return 0; 13310326f5a9SSrikar Dronamraju } 13320326f5a9SSrikar Dronamraju 13330326f5a9SSrikar Dronamraju /* 13340326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 13350326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 13360326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 13370326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 13380326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 13390326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 13400326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 13410326f5a9SSrikar Dronamraju */ 13420326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 13430326f5a9SSrikar Dronamraju { 13440326f5a9SSrikar Dronamraju struct task_struct *t = current; 13450326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13460326f5a9SSrikar Dronamraju 13470326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 13480326f5a9SSrikar Dronamraju return false; 13490326f5a9SSrikar Dronamraju 13500326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 13510326f5a9SSrikar Dronamraju 13520326f5a9SSrikar Dronamraju if (signal_pending(t)) { 13530326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 13540326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 13550326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 13560326f5a9SSrikar Dronamraju 13570326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 13580326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 13590326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 13600326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); 13610326f5a9SSrikar Dronamraju } 13620326f5a9SSrikar Dronamraju } 13630326f5a9SSrikar Dronamraju 13640326f5a9SSrikar Dronamraju return true; 13650326f5a9SSrikar Dronamraju } 13660326f5a9SSrikar Dronamraju 13670326f5a9SSrikar Dronamraju /* 13680326f5a9SSrikar Dronamraju * Avoid singlestepping the original instruction if the original instruction 13690326f5a9SSrikar Dronamraju * is a NOP or can be emulated. 13700326f5a9SSrikar Dronamraju */ 13710326f5a9SSrikar Dronamraju static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) 13720326f5a9SSrikar Dronamraju { 137371434f2fSOleg Nesterov if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) { 13740326f5a9SSrikar Dronamraju if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 13750326f5a9SSrikar Dronamraju return true; 137671434f2fSOleg Nesterov clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); 13770578a970SOleg Nesterov } 13780326f5a9SSrikar Dronamraju return false; 13790326f5a9SSrikar Dronamraju } 13800326f5a9SSrikar Dronamraju 1381499a4f3eSOleg Nesterov static void mmf_recalc_uprobes(struct mm_struct *mm) 1382499a4f3eSOleg Nesterov { 1383499a4f3eSOleg Nesterov struct vm_area_struct *vma; 1384499a4f3eSOleg Nesterov 1385499a4f3eSOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 1386499a4f3eSOleg Nesterov if (!valid_vma(vma, false)) 1387499a4f3eSOleg Nesterov continue; 1388499a4f3eSOleg Nesterov /* 1389499a4f3eSOleg Nesterov * This is not strictly accurate, we can race with 1390499a4f3eSOleg Nesterov * uprobe_unregister() and see the already removed 1391499a4f3eSOleg Nesterov * uprobe if delete_uprobe() was not yet called. 139263633cbfSOleg Nesterov * Or this uprobe can be filtered out. 1393499a4f3eSOleg Nesterov */ 1394499a4f3eSOleg Nesterov if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) 1395499a4f3eSOleg Nesterov return; 1396499a4f3eSOleg Nesterov } 1397499a4f3eSOleg Nesterov 1398499a4f3eSOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 1399499a4f3eSOleg Nesterov } 1400499a4f3eSOleg Nesterov 1401ec75fba9SOleg Nesterov static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) 1402ec75fba9SOleg Nesterov { 1403ec75fba9SOleg Nesterov struct page *page; 1404ec75fba9SOleg Nesterov uprobe_opcode_t opcode; 1405ec75fba9SOleg Nesterov int result; 1406ec75fba9SOleg Nesterov 1407ec75fba9SOleg Nesterov pagefault_disable(); 1408ec75fba9SOleg Nesterov result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, 1409ec75fba9SOleg Nesterov sizeof(opcode)); 1410ec75fba9SOleg Nesterov pagefault_enable(); 1411ec75fba9SOleg Nesterov 1412ec75fba9SOleg Nesterov if (likely(result == 0)) 1413ec75fba9SOleg Nesterov goto out; 1414ec75fba9SOleg Nesterov 1415ec75fba9SOleg Nesterov result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); 1416ec75fba9SOleg Nesterov if (result < 0) 1417ec75fba9SOleg Nesterov return result; 1418ec75fba9SOleg Nesterov 1419ec75fba9SOleg Nesterov copy_opcode(page, vaddr, &opcode); 1420ec75fba9SOleg Nesterov put_page(page); 1421ec75fba9SOleg Nesterov out: 1422ec75fba9SOleg Nesterov return is_swbp_insn(&opcode); 1423ec75fba9SOleg Nesterov } 1424ec75fba9SOleg Nesterov 1425d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 14260326f5a9SSrikar Dronamraju { 14273a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 14283a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 14290326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 14300326f5a9SSrikar Dronamraju 14310326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 14320326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 14333a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 14343a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 1435cb113b47SOleg Nesterov struct inode *inode = vma->vm_file->f_mapping->host; 1436cb113b47SOleg Nesterov loff_t offset = vaddr_to_offset(vma, bp_vaddr); 14370326f5a9SSrikar Dronamraju 14380326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 14390326f5a9SSrikar Dronamraju } 1440d790d346SOleg Nesterov 1441d790d346SOleg Nesterov if (!uprobe) 1442d790d346SOleg Nesterov *is_swbp = is_swbp_at_addr(mm, bp_vaddr); 1443d790d346SOleg Nesterov } else { 1444d790d346SOleg Nesterov *is_swbp = -EFAULT; 14453a9ea052SOleg Nesterov } 1446499a4f3eSOleg Nesterov 1447499a4f3eSOleg Nesterov if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) 1448499a4f3eSOleg Nesterov mmf_recalc_uprobes(mm); 14490326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 14500326f5a9SSrikar Dronamraju 14513a9ea052SOleg Nesterov return uprobe; 14523a9ea052SOleg Nesterov } 14533a9ea052SOleg Nesterov 1454da1816b1SOleg Nesterov static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 1455da1816b1SOleg Nesterov { 1456da1816b1SOleg Nesterov struct uprobe_consumer *uc; 1457da1816b1SOleg Nesterov int remove = UPROBE_HANDLER_REMOVE; 1458da1816b1SOleg Nesterov 1459da1816b1SOleg Nesterov down_read(&uprobe->register_rwsem); 1460da1816b1SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 1461da1816b1SOleg Nesterov int rc = uc->handler(uc, regs); 1462da1816b1SOleg Nesterov 1463da1816b1SOleg Nesterov WARN(rc & ~UPROBE_HANDLER_MASK, 1464da1816b1SOleg Nesterov "bad rc=0x%x from %pf()\n", rc, uc->handler); 1465da1816b1SOleg Nesterov remove &= rc; 1466da1816b1SOleg Nesterov } 1467da1816b1SOleg Nesterov 1468da1816b1SOleg Nesterov if (remove && uprobe->consumers) { 1469da1816b1SOleg Nesterov WARN_ON(!uprobe_is_active(uprobe)); 1470da1816b1SOleg Nesterov unapply_uprobe(uprobe, current->mm); 1471da1816b1SOleg Nesterov } 1472da1816b1SOleg Nesterov up_read(&uprobe->register_rwsem); 1473da1816b1SOleg Nesterov } 1474da1816b1SOleg Nesterov 14753a9ea052SOleg Nesterov /* 14763a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 14773a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 14783a9ea052SOleg Nesterov */ 14793a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 14803a9ea052SOleg Nesterov { 14813a9ea052SOleg Nesterov struct uprobe *uprobe; 14823a9ea052SOleg Nesterov unsigned long bp_vaddr; 148356bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 14843a9ea052SOleg Nesterov 14853a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 1486d790d346SOleg Nesterov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 14873a9ea052SOleg Nesterov 14880326f5a9SSrikar Dronamraju if (!uprobe) { 148956bb4cf6SOleg Nesterov if (is_swbp > 0) { 14900326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 14910326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 149256bb4cf6SOleg Nesterov } else { 149356bb4cf6SOleg Nesterov /* 149456bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 149556bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 149656bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 149756bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 149856bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 149956bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 150056bb4cf6SOleg Nesterov */ 150156bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 150256bb4cf6SOleg Nesterov } 15030326f5a9SSrikar Dronamraju return; 15040326f5a9SSrikar Dronamraju } 150574e59dfcSOleg Nesterov 150674e59dfcSOleg Nesterov /* change it in advance for ->handler() and restart */ 150774e59dfcSOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 150874e59dfcSOleg Nesterov 1509142b18ddSOleg Nesterov /* 1510142b18ddSOleg Nesterov * TODO: move copy_insn/etc into _register and remove this hack. 1511142b18ddSOleg Nesterov * After we hit the bp, _unregister + _register can install the 1512142b18ddSOleg Nesterov * new and not-yet-analyzed uprobe at the same address, restart. 1513142b18ddSOleg Nesterov */ 1514142b18ddSOleg Nesterov smp_rmb(); /* pairs with wmb() in install_breakpoint() */ 151571434f2fSOleg Nesterov if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) 151674e59dfcSOleg Nesterov goto out; 15170326f5a9SSrikar Dronamraju 15180326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 15190578a970SOleg Nesterov if (can_skip_sstep(uprobe, regs)) 15200578a970SOleg Nesterov goto out; 15210326f5a9SSrikar Dronamraju 1522*608e7427SOleg Nesterov if (!pre_ssout(uprobe, regs, bp_vaddr)) 15230326f5a9SSrikar Dronamraju return; 15240326f5a9SSrikar Dronamraju 152574e59dfcSOleg Nesterov /* can_skip_sstep() succeeded, or restart if can't singlestep */ 15260578a970SOleg Nesterov out: 15270326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15280326f5a9SSrikar Dronamraju } 15290326f5a9SSrikar Dronamraju 15300326f5a9SSrikar Dronamraju /* 15310326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 15320326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 15330326f5a9SSrikar Dronamraju */ 15340326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 15350326f5a9SSrikar Dronamraju { 15360326f5a9SSrikar Dronamraju struct uprobe *uprobe; 15370326f5a9SSrikar Dronamraju 15380326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 15390326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 15400326f5a9SSrikar Dronamraju arch_uprobe_post_xol(&uprobe->arch, regs); 15410326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 15420326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 15430326f5a9SSrikar Dronamraju else 15440326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 15450326f5a9SSrikar Dronamraju 15460326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15470326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15480326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 1549d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 15500326f5a9SSrikar Dronamraju 15510326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 15520326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 15530326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 15540326f5a9SSrikar Dronamraju } 15550326f5a9SSrikar Dronamraju 15560326f5a9SSrikar Dronamraju /* 15571b08e907SOleg Nesterov * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and 15581b08e907SOleg Nesterov * allows the thread to return from interrupt. After that handle_swbp() 15591b08e907SOleg Nesterov * sets utask->active_uprobe. 15600326f5a9SSrikar Dronamraju * 15611b08e907SOleg Nesterov * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag 15621b08e907SOleg Nesterov * and allows the thread to return from interrupt. 15630326f5a9SSrikar Dronamraju * 15640326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 15650326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 15660326f5a9SSrikar Dronamraju */ 15670326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 15680326f5a9SSrikar Dronamraju { 15690326f5a9SSrikar Dronamraju struct uprobe_task *utask; 15700326f5a9SSrikar Dronamraju 1571db023ea5SOleg Nesterov clear_thread_flag(TIF_UPROBE); 1572db023ea5SOleg Nesterov 15730326f5a9SSrikar Dronamraju utask = current->utask; 15741b08e907SOleg Nesterov if (utask && utask->active_uprobe) 15750326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 15761b08e907SOleg Nesterov else 15771b08e907SOleg Nesterov handle_swbp(regs); 15780326f5a9SSrikar Dronamraju } 15790326f5a9SSrikar Dronamraju 15800326f5a9SSrikar Dronamraju /* 15810326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 15820326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 15830326f5a9SSrikar Dronamraju */ 15840326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 15850326f5a9SSrikar Dronamraju { 1586f8ac4ec9SOleg Nesterov if (!current->mm || !test_bit(MMF_HAS_UPROBES, ¤t->mm->flags)) 15870326f5a9SSrikar Dronamraju return 0; 15880326f5a9SSrikar Dronamraju 15890326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 15900326f5a9SSrikar Dronamraju return 1; 15910326f5a9SSrikar Dronamraju } 15920326f5a9SSrikar Dronamraju 15930326f5a9SSrikar Dronamraju /* 15940326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 15950326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 15960326f5a9SSrikar Dronamraju */ 15970326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 15980326f5a9SSrikar Dronamraju { 15990326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 16000326f5a9SSrikar Dronamraju 16010326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 16020326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 16030326f5a9SSrikar Dronamraju return 0; 16040326f5a9SSrikar Dronamraju 16050326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 16060326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 16070326f5a9SSrikar Dronamraju return 1; 16080326f5a9SSrikar Dronamraju } 16090326f5a9SSrikar Dronamraju 16100326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 16110326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 16120326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 16130326f5a9SSrikar Dronamraju }; 16140326f5a9SSrikar Dronamraju 1615a5f4374aSIngo Molnar static int __init init_uprobes(void) 1616a5f4374aSIngo Molnar { 1617a5f4374aSIngo Molnar int i; 1618a5f4374aSIngo Molnar 161966d06dffSOleg Nesterov for (i = 0; i < UPROBES_HASH_SZ; i++) 1620a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 16210326f5a9SSrikar Dronamraju 162232cdba1eSOleg Nesterov if (percpu_init_rwsem(&dup_mmap_sem)) 162332cdba1eSOleg Nesterov return -ENOMEM; 162432cdba1eSOleg Nesterov 16250326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 1626a5f4374aSIngo Molnar } 16270326f5a9SSrikar Dronamraju module_init(init_uprobes); 1628a5f4374aSIngo Molnar 1629a5f4374aSIngo Molnar static void __exit exit_uprobes(void) 1630a5f4374aSIngo Molnar { 1631a5f4374aSIngo Molnar } 1632a5f4374aSIngo Molnar module_exit(exit_uprobes); 1633