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 */ 36a5f4374aSIngo Molnar 37a5f4374aSIngo Molnar #include <linux/uprobes.h> 38a5f4374aSIngo Molnar 39d4b3b638SSrikar Dronamraju #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) 40d4b3b638SSrikar Dronamraju #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE 41d4b3b638SSrikar Dronamraju 42a5f4374aSIngo Molnar static struct rb_root uprobes_tree = RB_ROOT; 43a5f4374aSIngo Molnar 44a5f4374aSIngo Molnar static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ 45a5f4374aSIngo Molnar 46a5f4374aSIngo Molnar #define UPROBES_HASH_SZ 13 47a5f4374aSIngo Molnar 48c5784de2SPeter Zijlstra /* 49c5784de2SPeter Zijlstra * We need separate register/unregister and mmap/munmap lock hashes because 50c5784de2SPeter Zijlstra * of mmap_sem nesting. 51c5784de2SPeter Zijlstra * 52c5784de2SPeter Zijlstra * uprobe_register() needs to install probes on (potentially) all processes 53c5784de2SPeter Zijlstra * and thus needs to acquire multiple mmap_sems (consequtively, not 54c5784de2SPeter Zijlstra * concurrently), whereas uprobe_mmap() is called while holding mmap_sem 55c5784de2SPeter Zijlstra * for the particular process doing the mmap. 56c5784de2SPeter Zijlstra * 57c5784de2SPeter Zijlstra * uprobe_register()->register_for_each_vma() needs to drop/acquire mmap_sem 58c5784de2SPeter Zijlstra * because of lock order against i_mmap_mutex. This means there's a hole in 59c5784de2SPeter Zijlstra * the register vma iteration where a mmap() can happen. 60c5784de2SPeter Zijlstra * 61c5784de2SPeter Zijlstra * Thus uprobe_register() can race with uprobe_mmap() and we can try and 62c5784de2SPeter Zijlstra * install a probe where one is already installed. 63c5784de2SPeter Zijlstra */ 64c5784de2SPeter Zijlstra 65a5f4374aSIngo Molnar /* serialize (un)register */ 66a5f4374aSIngo Molnar static struct mutex uprobes_mutex[UPROBES_HASH_SZ]; 67a5f4374aSIngo Molnar 68a5f4374aSIngo Molnar #define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 69a5f4374aSIngo Molnar 70a5f4374aSIngo Molnar /* serialize uprobe->pending_list */ 71a5f4374aSIngo Molnar static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; 72a5f4374aSIngo Molnar #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 73a5f4374aSIngo Molnar 74a5f4374aSIngo Molnar /* 75a5f4374aSIngo Molnar * uprobe_events allows us to skip the uprobe_mmap if there are no uprobe 76a5f4374aSIngo Molnar * events active at this time. Probably a fine grained per inode count is 77a5f4374aSIngo Molnar * better? 78a5f4374aSIngo Molnar */ 79a5f4374aSIngo Molnar static atomic_t uprobe_events = ATOMIC_INIT(0); 80a5f4374aSIngo Molnar 813ff54efdSSrikar Dronamraju struct uprobe { 823ff54efdSSrikar Dronamraju struct rb_node rb_node; /* node in the rb tree */ 833ff54efdSSrikar Dronamraju atomic_t ref; 843ff54efdSSrikar Dronamraju struct rw_semaphore consumer_rwsem; 853ff54efdSSrikar Dronamraju struct list_head pending_list; 863ff54efdSSrikar Dronamraju struct uprobe_consumer *consumers; 873ff54efdSSrikar Dronamraju struct inode *inode; /* Also hold a ref to inode */ 883ff54efdSSrikar Dronamraju loff_t offset; 893ff54efdSSrikar Dronamraju int flags; 903ff54efdSSrikar Dronamraju struct arch_uprobe arch; 913ff54efdSSrikar Dronamraju }; 923ff54efdSSrikar Dronamraju 93a5f4374aSIngo Molnar /* 94a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 95a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 96a5f4374aSIngo Molnar * changed after breakpoint was inserted. 97a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 98a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 99a5f4374aSIngo Molnar * executable vma. 100a5f4374aSIngo Molnar */ 101a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 102a5f4374aSIngo Molnar { 103a5f4374aSIngo Molnar if (!vma->vm_file) 104a5f4374aSIngo Molnar return false; 105a5f4374aSIngo Molnar 106a5f4374aSIngo Molnar if (!is_register) 107a5f4374aSIngo Molnar return true; 108a5f4374aSIngo Molnar 109ea131377SOleg Nesterov if ((vma->vm_flags & (VM_HUGETLB|VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) 110ea131377SOleg Nesterov == (VM_READ|VM_EXEC)) 111a5f4374aSIngo Molnar return true; 112a5f4374aSIngo Molnar 113a5f4374aSIngo Molnar return false; 114a5f4374aSIngo Molnar } 115a5f4374aSIngo Molnar 11657683f72SOleg Nesterov static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) 117a5f4374aSIngo Molnar { 11857683f72SOleg Nesterov return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); 119a5f4374aSIngo Molnar } 120a5f4374aSIngo Molnar 121cb113b47SOleg Nesterov static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) 122cb113b47SOleg Nesterov { 123cb113b47SOleg Nesterov return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); 124cb113b47SOleg Nesterov } 125cb113b47SOleg Nesterov 126a5f4374aSIngo Molnar /** 127a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 128a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 129a5f4374aSIngo Molnar * 130a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 131c517ee74SOleg Nesterov * @addr: address the old @page is mapped at 132a5f4374aSIngo Molnar * @page: the cowed page we are replacing by kpage 133a5f4374aSIngo Molnar * @kpage: the modified page we replace page by 134a5f4374aSIngo Molnar * 135a5f4374aSIngo Molnar * Returns 0 on success, -EFAULT on failure. 136a5f4374aSIngo Molnar */ 137c517ee74SOleg Nesterov static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 138c517ee74SOleg Nesterov struct page *page, struct page *kpage) 139a5f4374aSIngo Molnar { 140a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 1415323ce71SOleg Nesterov spinlock_t *ptl; 1425323ce71SOleg Nesterov pte_t *ptep; 1439f92448cSOleg Nesterov int err; 144a5f4374aSIngo Molnar 145194f8dcbSOleg Nesterov /* For try_to_free_swap() and munlock_vma_page() below */ 1469f92448cSOleg Nesterov lock_page(page); 1479f92448cSOleg Nesterov 1489f92448cSOleg Nesterov err = -EAGAIN; 1495323ce71SOleg Nesterov ptep = page_check_address(page, mm, addr, &ptl, 0); 150a5f4374aSIngo Molnar if (!ptep) 1519f92448cSOleg Nesterov goto unlock; 152a5f4374aSIngo Molnar 153a5f4374aSIngo Molnar get_page(kpage); 154a5f4374aSIngo Molnar page_add_new_anon_rmap(kpage, vma, addr); 155a5f4374aSIngo Molnar 1567396fa81SSrikar Dronamraju if (!PageAnon(page)) { 1577396fa81SSrikar Dronamraju dec_mm_counter(mm, MM_FILEPAGES); 1587396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1597396fa81SSrikar Dronamraju } 1607396fa81SSrikar Dronamraju 161a5f4374aSIngo Molnar flush_cache_page(vma, addr, pte_pfn(*ptep)); 162a5f4374aSIngo Molnar ptep_clear_flush(vma, addr, ptep); 163a5f4374aSIngo Molnar set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); 164a5f4374aSIngo Molnar 165a5f4374aSIngo Molnar page_remove_rmap(page); 166a5f4374aSIngo Molnar if (!page_mapped(page)) 167a5f4374aSIngo Molnar try_to_free_swap(page); 168a5f4374aSIngo Molnar pte_unmap_unlock(ptep, ptl); 169a5f4374aSIngo Molnar 170194f8dcbSOleg Nesterov if (vma->vm_flags & VM_LOCKED) 171194f8dcbSOleg Nesterov munlock_vma_page(page); 172194f8dcbSOleg Nesterov put_page(page); 173194f8dcbSOleg Nesterov 1749f92448cSOleg Nesterov err = 0; 1759f92448cSOleg Nesterov unlock: 1769f92448cSOleg Nesterov unlock_page(page); 1779f92448cSOleg Nesterov return err; 178a5f4374aSIngo Molnar } 179a5f4374aSIngo Molnar 180a5f4374aSIngo Molnar /** 1815cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 182a5f4374aSIngo Molnar * @insn: instruction to be checked. 1835cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 184a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 185a5f4374aSIngo Molnar */ 1865cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 187a5f4374aSIngo Molnar { 1885cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 189a5f4374aSIngo Molnar } 190a5f4374aSIngo Molnar 191a5f4374aSIngo Molnar /* 192a5f4374aSIngo Molnar * NOTE: 193a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 194a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 195a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 196a5f4374aSIngo Molnar * supported by that architecture then we need to modify read_opcode / 197a5f4374aSIngo Molnar * write_opcode accordingly. This would never be a problem for archs that 198a5f4374aSIngo Molnar * have fixed length instructions. 199a5f4374aSIngo Molnar */ 200a5f4374aSIngo Molnar 201a5f4374aSIngo Molnar /* 202a5f4374aSIngo Molnar * write_opcode - write the opcode at a given virtual address. 203e3343e6aSSrikar Dronamraju * @auprobe: arch breakpointing information. 204a5f4374aSIngo Molnar * @mm: the probed process address space. 205a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 206a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 207a5f4374aSIngo Molnar * 208a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 209a5f4374aSIngo Molnar * mm). 210a5f4374aSIngo Molnar * 211a5f4374aSIngo Molnar * For mm @mm, write the opcode at @vaddr. 212a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 213a5f4374aSIngo Molnar */ 214e3343e6aSSrikar Dronamraju static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, 215a5f4374aSIngo Molnar unsigned long vaddr, uprobe_opcode_t opcode) 216a5f4374aSIngo Molnar { 217a5f4374aSIngo Molnar struct page *old_page, *new_page; 218a5f4374aSIngo Molnar void *vaddr_old, *vaddr_new; 219a5f4374aSIngo Molnar struct vm_area_struct *vma; 220a5f4374aSIngo Molnar int ret; 221f403072cSOleg Nesterov 2225323ce71SOleg Nesterov retry: 223a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 224a5f4374aSIngo Molnar ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); 225a5f4374aSIngo Molnar if (ret <= 0) 226a5f4374aSIngo Molnar return ret; 227a5f4374aSIngo Molnar 228a5f4374aSIngo Molnar ret = -ENOMEM; 229a5f4374aSIngo Molnar new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); 230a5f4374aSIngo Molnar if (!new_page) 2319f92448cSOleg Nesterov goto put_old; 232a5f4374aSIngo Molnar 233a5f4374aSIngo Molnar __SetPageUptodate(new_page); 234a5f4374aSIngo Molnar 235a5f4374aSIngo Molnar /* copy the page now that we've got it stable */ 236a5f4374aSIngo Molnar vaddr_old = kmap_atomic(old_page); 237a5f4374aSIngo Molnar vaddr_new = kmap_atomic(new_page); 238a5f4374aSIngo Molnar 239a5f4374aSIngo Molnar memcpy(vaddr_new, vaddr_old, PAGE_SIZE); 240d9c4a30eSOleg Nesterov memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE); 241a5f4374aSIngo Molnar 242a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 243a5f4374aSIngo Molnar kunmap_atomic(vaddr_old); 244a5f4374aSIngo Molnar 245a5f4374aSIngo Molnar ret = anon_vma_prepare(vma); 246a5f4374aSIngo Molnar if (ret) 2479f92448cSOleg Nesterov goto put_new; 248a5f4374aSIngo Molnar 249c517ee74SOleg Nesterov ret = __replace_page(vma, vaddr, old_page, new_page); 250a5f4374aSIngo Molnar 2519f92448cSOleg Nesterov put_new: 252a5f4374aSIngo Molnar page_cache_release(new_page); 2539f92448cSOleg Nesterov put_old: 254a5f4374aSIngo Molnar put_page(old_page); 255a5f4374aSIngo Molnar 2565323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 2575323ce71SOleg Nesterov goto retry; 258a5f4374aSIngo Molnar return ret; 259a5f4374aSIngo Molnar } 260a5f4374aSIngo Molnar 261a5f4374aSIngo Molnar /** 262a5f4374aSIngo Molnar * read_opcode - read the opcode at a given virtual address. 263a5f4374aSIngo Molnar * @mm: the probed process address space. 264a5f4374aSIngo Molnar * @vaddr: the virtual address to read the opcode. 265a5f4374aSIngo Molnar * @opcode: location to store the read opcode. 266a5f4374aSIngo Molnar * 267a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 268a5f4374aSIngo Molnar * mm. 269a5f4374aSIngo Molnar * 270a5f4374aSIngo Molnar * For mm @mm, read the opcode at @vaddr and store it in @opcode. 271a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 272a5f4374aSIngo Molnar */ 273a5f4374aSIngo Molnar static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode) 274a5f4374aSIngo Molnar { 275a5f4374aSIngo Molnar struct page *page; 276a5f4374aSIngo Molnar void *vaddr_new; 277a5f4374aSIngo Molnar int ret; 278a5f4374aSIngo Molnar 279a3d7bb47SOleg Nesterov ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); 280a5f4374aSIngo Molnar if (ret <= 0) 281a5f4374aSIngo Molnar return ret; 282a5f4374aSIngo Molnar 283a5f4374aSIngo Molnar vaddr_new = kmap_atomic(page); 284a5f4374aSIngo Molnar vaddr &= ~PAGE_MASK; 2855cb4ac3aSSrikar Dronamraju memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE); 286a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 287a5f4374aSIngo Molnar 288a5f4374aSIngo Molnar put_page(page); 289a5f4374aSIngo Molnar 290a5f4374aSIngo Molnar return 0; 291a5f4374aSIngo Molnar } 292a5f4374aSIngo Molnar 2935cb4ac3aSSrikar Dronamraju static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) 294a5f4374aSIngo Molnar { 295a5f4374aSIngo Molnar uprobe_opcode_t opcode; 296a5f4374aSIngo Molnar int result; 297a5f4374aSIngo Molnar 298c00b2750SOleg Nesterov if (current->mm == mm) { 299c00b2750SOleg Nesterov pagefault_disable(); 300c00b2750SOleg Nesterov result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, 301c00b2750SOleg Nesterov sizeof(opcode)); 302c00b2750SOleg Nesterov pagefault_enable(); 303c00b2750SOleg Nesterov 304c00b2750SOleg Nesterov if (likely(result == 0)) 305c00b2750SOleg Nesterov goto out; 306c00b2750SOleg Nesterov } 307c00b2750SOleg Nesterov 308a5f4374aSIngo Molnar result = read_opcode(mm, vaddr, &opcode); 309a5f4374aSIngo Molnar if (result) 310a5f4374aSIngo Molnar return result; 311c00b2750SOleg Nesterov out: 3125cb4ac3aSSrikar Dronamraju if (is_swbp_insn(&opcode)) 313a5f4374aSIngo Molnar return 1; 314a5f4374aSIngo Molnar 315a5f4374aSIngo Molnar return 0; 316a5f4374aSIngo Molnar } 317a5f4374aSIngo Molnar 318a5f4374aSIngo Molnar /** 3195cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 320e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 321a5f4374aSIngo Molnar * @mm: the probed process address space. 322a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 323a5f4374aSIngo Molnar * 324a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 325a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 326a5f4374aSIngo Molnar */ 3275cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 328a5f4374aSIngo Molnar { 329a5f4374aSIngo Molnar int result; 330c5784de2SPeter Zijlstra /* 331c5784de2SPeter Zijlstra * See the comment near uprobes_hash(). 332c5784de2SPeter Zijlstra */ 3335cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 334a5f4374aSIngo Molnar if (result == 1) 33578f74116SOleg Nesterov return 0; 336a5f4374aSIngo Molnar 337a5f4374aSIngo Molnar if (result) 338a5f4374aSIngo Molnar return result; 339a5f4374aSIngo Molnar 3405cb4ac3aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); 341a5f4374aSIngo Molnar } 342a5f4374aSIngo Molnar 343a5f4374aSIngo Molnar /** 344a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 345a5f4374aSIngo Molnar * @mm: the probed process address space. 346e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 347a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 348a5f4374aSIngo Molnar * 349a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 350a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 351a5f4374aSIngo Molnar */ 352a5f4374aSIngo Molnar int __weak 353ded86e7cSOleg Nesterov set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 354a5f4374aSIngo Molnar { 355a5f4374aSIngo Molnar int result; 356a5f4374aSIngo Molnar 3575cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 358a5f4374aSIngo Molnar if (!result) 359a5f4374aSIngo Molnar return -EINVAL; 360a5f4374aSIngo Molnar 361a5f4374aSIngo Molnar if (result != 1) 362a5f4374aSIngo Molnar return result; 363ded86e7cSOleg Nesterov 364e3343e6aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); 365a5f4374aSIngo Molnar } 366a5f4374aSIngo Molnar 367a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 368a5f4374aSIngo Molnar { 369a5f4374aSIngo Molnar if (l->inode < r->inode) 370a5f4374aSIngo Molnar return -1; 371a5f4374aSIngo Molnar 372a5f4374aSIngo Molnar if (l->inode > r->inode) 373a5f4374aSIngo Molnar return 1; 374a5f4374aSIngo Molnar 375a5f4374aSIngo Molnar if (l->offset < r->offset) 376a5f4374aSIngo Molnar return -1; 377a5f4374aSIngo Molnar 378a5f4374aSIngo Molnar if (l->offset > r->offset) 379a5f4374aSIngo Molnar return 1; 380a5f4374aSIngo Molnar 381a5f4374aSIngo Molnar return 0; 382a5f4374aSIngo Molnar } 383a5f4374aSIngo Molnar 384a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 385a5f4374aSIngo Molnar { 386a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 387a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 388a5f4374aSIngo Molnar struct uprobe *uprobe; 389a5f4374aSIngo Molnar int match; 390a5f4374aSIngo Molnar 391a5f4374aSIngo Molnar while (n) { 392a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 393a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 394a5f4374aSIngo Molnar if (!match) { 395a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 396a5f4374aSIngo Molnar return uprobe; 397a5f4374aSIngo Molnar } 398a5f4374aSIngo Molnar 399a5f4374aSIngo Molnar if (match < 0) 400a5f4374aSIngo Molnar n = n->rb_left; 401a5f4374aSIngo Molnar else 402a5f4374aSIngo Molnar n = n->rb_right; 403a5f4374aSIngo Molnar } 404a5f4374aSIngo Molnar return NULL; 405a5f4374aSIngo Molnar } 406a5f4374aSIngo Molnar 407a5f4374aSIngo Molnar /* 408a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 409a5f4374aSIngo Molnar * Acquires uprobes_treelock 410a5f4374aSIngo Molnar */ 411a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 412a5f4374aSIngo Molnar { 413a5f4374aSIngo Molnar struct uprobe *uprobe; 414a5f4374aSIngo Molnar 4156f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 416a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 4176f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 418a5f4374aSIngo Molnar 419a5f4374aSIngo Molnar return uprobe; 420a5f4374aSIngo Molnar } 421a5f4374aSIngo Molnar 422a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 423a5f4374aSIngo Molnar { 424a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 425a5f4374aSIngo Molnar struct rb_node *parent = NULL; 426a5f4374aSIngo Molnar struct uprobe *u; 427a5f4374aSIngo Molnar int match; 428a5f4374aSIngo Molnar 429a5f4374aSIngo Molnar while (*p) { 430a5f4374aSIngo Molnar parent = *p; 431a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 432a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 433a5f4374aSIngo Molnar if (!match) { 434a5f4374aSIngo Molnar atomic_inc(&u->ref); 435a5f4374aSIngo Molnar return u; 436a5f4374aSIngo Molnar } 437a5f4374aSIngo Molnar 438a5f4374aSIngo Molnar if (match < 0) 439a5f4374aSIngo Molnar p = &parent->rb_left; 440a5f4374aSIngo Molnar else 441a5f4374aSIngo Molnar p = &parent->rb_right; 442a5f4374aSIngo Molnar 443a5f4374aSIngo Molnar } 444a5f4374aSIngo Molnar 445a5f4374aSIngo Molnar u = NULL; 446a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 447a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 448a5f4374aSIngo Molnar /* get access + creation ref */ 449a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 450a5f4374aSIngo Molnar 451a5f4374aSIngo Molnar return u; 452a5f4374aSIngo Molnar } 453a5f4374aSIngo Molnar 454a5f4374aSIngo Molnar /* 455a5f4374aSIngo Molnar * Acquire uprobes_treelock. 456a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 457a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 458a5f4374aSIngo Molnar * 459a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 460a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 461a5f4374aSIngo Molnar */ 462a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 463a5f4374aSIngo Molnar { 464a5f4374aSIngo Molnar struct uprobe *u; 465a5f4374aSIngo Molnar 4666f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 467a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 4686f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 469a5f4374aSIngo Molnar 4700326f5a9SSrikar Dronamraju /* For now assume that the instruction need not be single-stepped */ 4710326f5a9SSrikar Dronamraju uprobe->flags |= UPROBE_SKIP_SSTEP; 4720326f5a9SSrikar Dronamraju 473a5f4374aSIngo Molnar return u; 474a5f4374aSIngo Molnar } 475a5f4374aSIngo Molnar 476a5f4374aSIngo Molnar static void put_uprobe(struct uprobe *uprobe) 477a5f4374aSIngo Molnar { 478a5f4374aSIngo Molnar if (atomic_dec_and_test(&uprobe->ref)) 479a5f4374aSIngo Molnar kfree(uprobe); 480a5f4374aSIngo Molnar } 481a5f4374aSIngo Molnar 482a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 483a5f4374aSIngo Molnar { 484a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 485a5f4374aSIngo Molnar 486a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 487a5f4374aSIngo Molnar if (!uprobe) 488a5f4374aSIngo Molnar return NULL; 489a5f4374aSIngo Molnar 490a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 491a5f4374aSIngo Molnar uprobe->offset = offset; 492a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 493a5f4374aSIngo Molnar 494a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 495a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 496a5f4374aSIngo Molnar 497a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 498a5f4374aSIngo Molnar if (cur_uprobe) { 499a5f4374aSIngo Molnar kfree(uprobe); 500a5f4374aSIngo Molnar uprobe = cur_uprobe; 501a5f4374aSIngo Molnar iput(inode); 502a5f4374aSIngo Molnar } else { 503a5f4374aSIngo Molnar atomic_inc(&uprobe_events); 504a5f4374aSIngo Molnar } 505a5f4374aSIngo Molnar 506a5f4374aSIngo Molnar return uprobe; 507a5f4374aSIngo Molnar } 508a5f4374aSIngo Molnar 5090326f5a9SSrikar Dronamraju static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 5100326f5a9SSrikar Dronamraju { 5110326f5a9SSrikar Dronamraju struct uprobe_consumer *uc; 5120326f5a9SSrikar Dronamraju 5130326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_RUN_HANDLER)) 5140326f5a9SSrikar Dronamraju return; 5150326f5a9SSrikar Dronamraju 5160326f5a9SSrikar Dronamraju down_read(&uprobe->consumer_rwsem); 5170326f5a9SSrikar Dronamraju for (uc = uprobe->consumers; uc; uc = uc->next) { 5180326f5a9SSrikar Dronamraju if (!uc->filter || uc->filter(uc, current)) 5190326f5a9SSrikar Dronamraju uc->handler(uc, regs); 5200326f5a9SSrikar Dronamraju } 5210326f5a9SSrikar Dronamraju up_read(&uprobe->consumer_rwsem); 5220326f5a9SSrikar Dronamraju } 5230326f5a9SSrikar Dronamraju 524a5f4374aSIngo Molnar /* Returns the previous consumer */ 525a5f4374aSIngo Molnar static struct uprobe_consumer * 526e3343e6aSSrikar Dronamraju consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 527a5f4374aSIngo Molnar { 528a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 529e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 530e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 531a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 532a5f4374aSIngo Molnar 533e3343e6aSSrikar Dronamraju return uc->next; 534a5f4374aSIngo Molnar } 535a5f4374aSIngo Molnar 536a5f4374aSIngo Molnar /* 537e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 538e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 539a5f4374aSIngo Molnar * or return false. 540a5f4374aSIngo Molnar */ 541e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 542a5f4374aSIngo Molnar { 543a5f4374aSIngo Molnar struct uprobe_consumer **con; 544a5f4374aSIngo Molnar bool ret = false; 545a5f4374aSIngo Molnar 546a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 547a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 548e3343e6aSSrikar Dronamraju if (*con == uc) { 549e3343e6aSSrikar Dronamraju *con = uc->next; 550a5f4374aSIngo Molnar ret = true; 551a5f4374aSIngo Molnar break; 552a5f4374aSIngo Molnar } 553a5f4374aSIngo Molnar } 554a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 555a5f4374aSIngo Molnar 556a5f4374aSIngo Molnar return ret; 557a5f4374aSIngo Molnar } 558a5f4374aSIngo Molnar 559e3343e6aSSrikar Dronamraju static int 560d436615eSOleg Nesterov __copy_insn(struct address_space *mapping, struct file *filp, char *insn, 561593609a5SOleg Nesterov unsigned long nbytes, loff_t offset) 562a5f4374aSIngo Molnar { 563a5f4374aSIngo Molnar struct page *page; 564a5f4374aSIngo Molnar void *vaddr; 565593609a5SOleg Nesterov unsigned long off; 566593609a5SOleg Nesterov pgoff_t idx; 567a5f4374aSIngo Molnar 568a5f4374aSIngo Molnar if (!filp) 569a5f4374aSIngo Molnar return -EINVAL; 570a5f4374aSIngo Molnar 571cc359d18SOleg Nesterov if (!mapping->a_ops->readpage) 572cc359d18SOleg Nesterov return -EIO; 573cc359d18SOleg Nesterov 574593609a5SOleg Nesterov idx = offset >> PAGE_CACHE_SHIFT; 575593609a5SOleg Nesterov off = offset & ~PAGE_MASK; 576a5f4374aSIngo Molnar 577a5f4374aSIngo Molnar /* 578a5f4374aSIngo Molnar * Ensure that the page that has the original instruction is 579a5f4374aSIngo Molnar * populated and in page-cache. 580a5f4374aSIngo Molnar */ 581a5f4374aSIngo Molnar page = read_mapping_page(mapping, idx, filp); 582a5f4374aSIngo Molnar if (IS_ERR(page)) 583a5f4374aSIngo Molnar return PTR_ERR(page); 584a5f4374aSIngo Molnar 585a5f4374aSIngo Molnar vaddr = kmap_atomic(page); 586593609a5SOleg Nesterov memcpy(insn, vaddr + off, nbytes); 587a5f4374aSIngo Molnar kunmap_atomic(vaddr); 588a5f4374aSIngo Molnar page_cache_release(page); 589a5f4374aSIngo Molnar 590a5f4374aSIngo Molnar return 0; 591a5f4374aSIngo Molnar } 592a5f4374aSIngo Molnar 593d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 594a5f4374aSIngo Molnar { 595a5f4374aSIngo Molnar struct address_space *mapping; 596a5f4374aSIngo Molnar unsigned long nbytes; 597a5f4374aSIngo Molnar int bytes; 598a5f4374aSIngo Molnar 599d436615eSOleg Nesterov nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); 600a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 601a5f4374aSIngo Molnar 602a5f4374aSIngo Molnar /* Instruction at end of binary; copy only available bytes */ 603a5f4374aSIngo Molnar if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) 604a5f4374aSIngo Molnar bytes = uprobe->inode->i_size - uprobe->offset; 605a5f4374aSIngo Molnar else 606a5f4374aSIngo Molnar bytes = MAX_UINSN_BYTES; 607a5f4374aSIngo Molnar 608a5f4374aSIngo Molnar /* Instruction at the page-boundary; copy bytes in second page */ 609a5f4374aSIngo Molnar if (nbytes < bytes) { 610fc36f595SOleg Nesterov int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, 611fc36f595SOleg Nesterov bytes - nbytes, uprobe->offset + nbytes); 612fc36f595SOleg Nesterov if (err) 613fc36f595SOleg Nesterov return err; 614a5f4374aSIngo Molnar bytes = nbytes; 615a5f4374aSIngo Molnar } 616d436615eSOleg Nesterov return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); 617a5f4374aSIngo Molnar } 618a5f4374aSIngo Molnar 619682968e0SSrikar Dronamraju /* 620682968e0SSrikar Dronamraju * How mm->uprobes_state.count gets updated 621682968e0SSrikar Dronamraju * uprobe_mmap() increments the count if 622682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 623682968e0SSrikar Dronamraju * - it cannot add a breakpoint, but sees that there is a underlying 624682968e0SSrikar Dronamraju * breakpoint (via a is_swbp_at_addr()). 625682968e0SSrikar Dronamraju * 626682968e0SSrikar Dronamraju * uprobe_munmap() decrements the count if 627682968e0SSrikar Dronamraju * - it sees a underlying breakpoint, (via is_swbp_at_addr) 628682968e0SSrikar Dronamraju * (Subsequent uprobe_unregister wouldnt find the breakpoint 629682968e0SSrikar Dronamraju * unless a uprobe_mmap kicks in, since the old vma would be 630682968e0SSrikar Dronamraju * dropped just after uprobe_munmap.) 631682968e0SSrikar Dronamraju * 632682968e0SSrikar Dronamraju * uprobe_register increments the count if: 633682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 634682968e0SSrikar Dronamraju * 635682968e0SSrikar Dronamraju * uprobe_unregister decrements the count if: 636682968e0SSrikar Dronamraju * - it sees a underlying breakpoint and removes successfully. 637682968e0SSrikar Dronamraju * (via is_swbp_at_addr) 638682968e0SSrikar Dronamraju * (Subsequent uprobe_munmap wouldnt find the breakpoint 639682968e0SSrikar Dronamraju * since there is no underlying breakpoint after the 640682968e0SSrikar Dronamraju * breakpoint removal.) 641682968e0SSrikar Dronamraju */ 642e3343e6aSSrikar Dronamraju static int 643e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 644816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 645a5f4374aSIngo Molnar { 646f8ac4ec9SOleg Nesterov bool first_uprobe; 647a5f4374aSIngo Molnar int ret; 648a5f4374aSIngo Molnar 649a5f4374aSIngo Molnar /* 650a5f4374aSIngo Molnar * If probe is being deleted, unregister thread could be done with 651a5f4374aSIngo Molnar * the vma-rmap-walk through. Adding a probe now can be fatal since 652a5f4374aSIngo Molnar * nobody will be able to cleanup. Also we could be from fork or 653a5f4374aSIngo Molnar * mremap path, where the probe might have already been inserted. 654a5f4374aSIngo Molnar * Hence behave as if probe already existed. 655a5f4374aSIngo Molnar */ 656a5f4374aSIngo Molnar if (!uprobe->consumers) 65778f74116SOleg Nesterov return 0; 658a5f4374aSIngo Molnar 659900771a4SSrikar Dronamraju if (!(uprobe->flags & UPROBE_COPY_INSN)) { 660d436615eSOleg Nesterov ret = copy_insn(uprobe, vma->vm_file); 661a5f4374aSIngo Molnar if (ret) 662a5f4374aSIngo Molnar return ret; 663a5f4374aSIngo Molnar 6645cb4ac3aSSrikar Dronamraju if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) 665c1914a09SOleg Nesterov return -ENOTSUPP; 666a5f4374aSIngo Molnar 667816c03fbSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 668a5f4374aSIngo Molnar if (ret) 669a5f4374aSIngo Molnar return ret; 670a5f4374aSIngo Molnar 671d9c4a30eSOleg Nesterov /* write_opcode() assumes we don't cross page boundary */ 672d9c4a30eSOleg Nesterov BUG_ON((uprobe->offset & ~PAGE_MASK) + 673d9c4a30eSOleg Nesterov UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 674d9c4a30eSOleg Nesterov 675900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_COPY_INSN; 676a5f4374aSIngo Molnar } 677682968e0SSrikar Dronamraju 678f8ac4ec9SOleg Nesterov /* 679f8ac4ec9SOleg Nesterov * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), 680f8ac4ec9SOleg Nesterov * the task can hit this breakpoint right after __replace_page(). 681f8ac4ec9SOleg Nesterov */ 682f8ac4ec9SOleg Nesterov first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); 683f8ac4ec9SOleg Nesterov if (first_uprobe) 684f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &mm->flags); 685f8ac4ec9SOleg Nesterov 686816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 6879f68f672SOleg Nesterov if (!ret) 6889f68f672SOleg Nesterov clear_bit(MMF_RECALC_UPROBES, &mm->flags); 6899f68f672SOleg Nesterov else if (first_uprobe) 690f8ac4ec9SOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 691a5f4374aSIngo Molnar 692a5f4374aSIngo Molnar return ret; 693a5f4374aSIngo Molnar } 694a5f4374aSIngo Molnar 695e3343e6aSSrikar Dronamraju static void 696816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 697a5f4374aSIngo Molnar { 6989f68f672SOleg Nesterov /* can happen if uprobe_register() fails */ 6999f68f672SOleg Nesterov if (!test_bit(MMF_HAS_UPROBES, &mm->flags)) 7009f68f672SOleg Nesterov return; 7019f68f672SOleg Nesterov 7029f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &mm->flags); 703ded86e7cSOleg Nesterov set_orig_insn(&uprobe->arch, mm, vaddr); 704a5f4374aSIngo Molnar } 705a5f4374aSIngo Molnar 7060326f5a9SSrikar Dronamraju /* 707778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 708778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 709778b032dSOleg Nesterov * See find_active_uprobe(). 7100326f5a9SSrikar Dronamraju */ 711a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 712a5f4374aSIngo Molnar { 7136f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 714a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 7156f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 716a5f4374aSIngo Molnar iput(uprobe->inode); 717a5f4374aSIngo Molnar put_uprobe(uprobe); 718a5f4374aSIngo Molnar atomic_dec(&uprobe_events); 719a5f4374aSIngo Molnar } 720a5f4374aSIngo Molnar 72126872090SOleg Nesterov struct map_info { 72226872090SOleg Nesterov struct map_info *next; 72326872090SOleg Nesterov struct mm_struct *mm; 724816c03fbSOleg Nesterov unsigned long vaddr; 72526872090SOleg Nesterov }; 72626872090SOleg Nesterov 72726872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 728a5f4374aSIngo Molnar { 72926872090SOleg Nesterov struct map_info *next = info->next; 73026872090SOleg Nesterov kfree(info); 73126872090SOleg Nesterov return next; 73226872090SOleg Nesterov } 73326872090SOleg Nesterov 73426872090SOleg Nesterov static struct map_info * 73526872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 73626872090SOleg Nesterov { 73726872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 738a5f4374aSIngo Molnar struct prio_tree_iter iter; 739a5f4374aSIngo Molnar struct vm_area_struct *vma; 74026872090SOleg Nesterov struct map_info *curr = NULL; 74126872090SOleg Nesterov struct map_info *prev = NULL; 74226872090SOleg Nesterov struct map_info *info; 74326872090SOleg Nesterov int more = 0; 744a5f4374aSIngo Molnar 74526872090SOleg Nesterov again: 74626872090SOleg Nesterov mutex_lock(&mapping->i_mmap_mutex); 747a5f4374aSIngo Molnar vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 748a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 749a5f4374aSIngo Molnar continue; 750a5f4374aSIngo Molnar 7517a5bfb66SOleg Nesterov if (!prev && !more) { 7527a5bfb66SOleg Nesterov /* 7537a5bfb66SOleg Nesterov * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through 7547a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 7557a5bfb66SOleg Nesterov */ 7567a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 7577a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 7587a5bfb66SOleg Nesterov if (prev) 7597a5bfb66SOleg Nesterov prev->next = NULL; 7607a5bfb66SOleg Nesterov } 76126872090SOleg Nesterov if (!prev) { 76226872090SOleg Nesterov more++; 76326872090SOleg Nesterov continue; 764a5f4374aSIngo Molnar } 765a5f4374aSIngo Molnar 76626872090SOleg Nesterov if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) 76726872090SOleg Nesterov continue; 768a5f4374aSIngo Molnar 76926872090SOleg Nesterov info = prev; 77026872090SOleg Nesterov prev = prev->next; 77126872090SOleg Nesterov info->next = curr; 77226872090SOleg Nesterov curr = info; 77326872090SOleg Nesterov 77426872090SOleg Nesterov info->mm = vma->vm_mm; 77557683f72SOleg Nesterov info->vaddr = offset_to_vaddr(vma, offset); 776a5f4374aSIngo Molnar } 777a5f4374aSIngo Molnar mutex_unlock(&mapping->i_mmap_mutex); 778a5f4374aSIngo Molnar 77926872090SOleg Nesterov if (!more) 78026872090SOleg Nesterov goto out; 781a5f4374aSIngo Molnar 78226872090SOleg Nesterov prev = curr; 78326872090SOleg Nesterov while (curr) { 78426872090SOleg Nesterov mmput(curr->mm); 78526872090SOleg Nesterov curr = curr->next; 78626872090SOleg Nesterov } 78726872090SOleg Nesterov 78826872090SOleg Nesterov do { 78926872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 79026872090SOleg Nesterov if (!info) { 79126872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 79226872090SOleg Nesterov goto out; 79326872090SOleg Nesterov } 79426872090SOleg Nesterov info->next = prev; 79526872090SOleg Nesterov prev = info; 79626872090SOleg Nesterov } while (--more); 79726872090SOleg Nesterov 79826872090SOleg Nesterov goto again; 79926872090SOleg Nesterov out: 80026872090SOleg Nesterov while (prev) 80126872090SOleg Nesterov prev = free_map_info(prev); 80226872090SOleg Nesterov return curr; 803a5f4374aSIngo Molnar } 804a5f4374aSIngo Molnar 805a5f4374aSIngo Molnar static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 806a5f4374aSIngo Molnar { 80726872090SOleg Nesterov struct map_info *info; 80826872090SOleg Nesterov int err = 0; 80926872090SOleg Nesterov 81026872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 81126872090SOleg Nesterov uprobe->offset, is_register); 81226872090SOleg Nesterov if (IS_ERR(info)) 81326872090SOleg Nesterov return PTR_ERR(info); 81426872090SOleg Nesterov 81526872090SOleg Nesterov while (info) { 81626872090SOleg Nesterov struct mm_struct *mm = info->mm; 817a5f4374aSIngo Molnar struct vm_area_struct *vma; 818a5f4374aSIngo Molnar 81926872090SOleg Nesterov if (err) 82026872090SOleg Nesterov goto free; 821a5f4374aSIngo Molnar 82277fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 823f4d6dfe5SOleg Nesterov vma = find_vma(mm, info->vaddr); 824f4d6dfe5SOleg Nesterov if (!vma || !valid_vma(vma, is_register) || 825f4d6dfe5SOleg Nesterov vma->vm_file->f_mapping->host != uprobe->inode) 82626872090SOleg Nesterov goto unlock; 82726872090SOleg Nesterov 828f4d6dfe5SOleg Nesterov if (vma->vm_start > info->vaddr || 829f4d6dfe5SOleg Nesterov vaddr_to_offset(vma, info->vaddr) != uprobe->offset) 83026872090SOleg Nesterov goto unlock; 831a5f4374aSIngo Molnar 83278f74116SOleg Nesterov if (is_register) 83326872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 83478f74116SOleg Nesterov else 83526872090SOleg Nesterov remove_breakpoint(uprobe, mm, info->vaddr); 83678f74116SOleg Nesterov 83726872090SOleg Nesterov unlock: 83826872090SOleg Nesterov up_write(&mm->mmap_sem); 83926872090SOleg Nesterov free: 84026872090SOleg Nesterov mmput(mm); 84126872090SOleg Nesterov info = free_map_info(info); 842a5f4374aSIngo Molnar } 843a5f4374aSIngo Molnar 84426872090SOleg Nesterov return err; 845a5f4374aSIngo Molnar } 846a5f4374aSIngo Molnar 847a5f4374aSIngo Molnar static int __uprobe_register(struct uprobe *uprobe) 848a5f4374aSIngo Molnar { 849a5f4374aSIngo Molnar return register_for_each_vma(uprobe, true); 850a5f4374aSIngo Molnar } 851a5f4374aSIngo Molnar 852a5f4374aSIngo Molnar static void __uprobe_unregister(struct uprobe *uprobe) 853a5f4374aSIngo Molnar { 854a5f4374aSIngo Molnar if (!register_for_each_vma(uprobe, false)) 855a5f4374aSIngo Molnar delete_uprobe(uprobe); 856a5f4374aSIngo Molnar 857a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 858a5f4374aSIngo Molnar } 859a5f4374aSIngo Molnar 860a5f4374aSIngo Molnar /* 861a5f4374aSIngo Molnar * uprobe_register - register a probe 862a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 863a5f4374aSIngo Molnar * @offset: offset from the start of the file. 864e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 865a5f4374aSIngo Molnar * 866a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 867a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 868a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 869a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 870a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 871e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 872a5f4374aSIngo Molnar * unregisters. 873a5f4374aSIngo Molnar * 874a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 875a5f4374aSIngo Molnar * else return 0 (success) 876a5f4374aSIngo Molnar */ 877e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 878a5f4374aSIngo Molnar { 879a5f4374aSIngo Molnar struct uprobe *uprobe; 880a5f4374aSIngo Molnar int ret; 881a5f4374aSIngo Molnar 882e3343e6aSSrikar Dronamraju if (!inode || !uc || uc->next) 883a5f4374aSIngo Molnar return -EINVAL; 884a5f4374aSIngo Molnar 885a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 886a5f4374aSIngo Molnar return -EINVAL; 887a5f4374aSIngo Molnar 888a5f4374aSIngo Molnar ret = 0; 889a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 890a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 891a5f4374aSIngo Molnar 892e3343e6aSSrikar Dronamraju if (uprobe && !consumer_add(uprobe, uc)) { 893a5f4374aSIngo Molnar ret = __uprobe_register(uprobe); 894a5f4374aSIngo Molnar if (ret) { 895a5f4374aSIngo Molnar uprobe->consumers = NULL; 896a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 897a5f4374aSIngo Molnar } else { 898900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_RUN_HANDLER; 899a5f4374aSIngo Molnar } 900a5f4374aSIngo Molnar } 901a5f4374aSIngo Molnar 902a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 9036d1d8dfaSSebastian Andrzej Siewior if (uprobe) 904a5f4374aSIngo Molnar put_uprobe(uprobe); 905a5f4374aSIngo Molnar 906a5f4374aSIngo Molnar return ret; 907a5f4374aSIngo Molnar } 908a5f4374aSIngo Molnar 909a5f4374aSIngo Molnar /* 910a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 911a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 912a5f4374aSIngo Molnar * @offset: offset from the start of the file. 913e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 914a5f4374aSIngo Molnar */ 915e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 916a5f4374aSIngo Molnar { 917a5f4374aSIngo Molnar struct uprobe *uprobe; 918a5f4374aSIngo Molnar 919e3343e6aSSrikar Dronamraju if (!inode || !uc) 920a5f4374aSIngo Molnar return; 921a5f4374aSIngo Molnar 922a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 923a5f4374aSIngo Molnar if (!uprobe) 924a5f4374aSIngo Molnar return; 925a5f4374aSIngo Molnar 926a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 927a5f4374aSIngo Molnar 928e3343e6aSSrikar Dronamraju if (consumer_del(uprobe, uc)) { 929a5f4374aSIngo Molnar if (!uprobe->consumers) { 930a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 931900771a4SSrikar Dronamraju uprobe->flags &= ~UPROBE_RUN_HANDLER; 932a5f4374aSIngo Molnar } 933a5f4374aSIngo Molnar } 934a5f4374aSIngo Molnar 935a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 936a5f4374aSIngo Molnar if (uprobe) 937a5f4374aSIngo Molnar put_uprobe(uprobe); 938a5f4374aSIngo Molnar } 939a5f4374aSIngo Molnar 940891c3970SOleg Nesterov static struct rb_node * 941891c3970SOleg Nesterov find_node_in_range(struct inode *inode, loff_t min, loff_t max) 942a5f4374aSIngo Molnar { 943a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 944a5f4374aSIngo Molnar 945a5f4374aSIngo Molnar while (n) { 946891c3970SOleg Nesterov struct uprobe *u = rb_entry(n, struct uprobe, rb_node); 947a5f4374aSIngo Molnar 948891c3970SOleg Nesterov if (inode < u->inode) { 949a5f4374aSIngo Molnar n = n->rb_left; 950891c3970SOleg Nesterov } else if (inode > u->inode) { 951a5f4374aSIngo Molnar n = n->rb_right; 952891c3970SOleg Nesterov } else { 953891c3970SOleg Nesterov if (max < u->offset) 954891c3970SOleg Nesterov n = n->rb_left; 955891c3970SOleg Nesterov else if (min > u->offset) 956891c3970SOleg Nesterov n = n->rb_right; 957891c3970SOleg Nesterov else 958891c3970SOleg Nesterov break; 959891c3970SOleg Nesterov } 960a5f4374aSIngo Molnar } 961a5f4374aSIngo Molnar 962891c3970SOleg Nesterov return n; 963a5f4374aSIngo Molnar } 964a5f4374aSIngo Molnar 965a5f4374aSIngo Molnar /* 966891c3970SOleg Nesterov * For a given range in vma, build a list of probes that need to be inserted. 967a5f4374aSIngo Molnar */ 968891c3970SOleg Nesterov static void build_probe_list(struct inode *inode, 969891c3970SOleg Nesterov struct vm_area_struct *vma, 970891c3970SOleg Nesterov unsigned long start, unsigned long end, 971891c3970SOleg Nesterov struct list_head *head) 972a5f4374aSIngo Molnar { 973891c3970SOleg Nesterov loff_t min, max; 974891c3970SOleg Nesterov struct rb_node *n, *t; 975891c3970SOleg Nesterov struct uprobe *u; 976891c3970SOleg Nesterov 977891c3970SOleg Nesterov INIT_LIST_HEAD(head); 978cb113b47SOleg Nesterov min = vaddr_to_offset(vma, start); 979891c3970SOleg Nesterov max = min + (end - start) - 1; 980a5f4374aSIngo Molnar 9816f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 982891c3970SOleg Nesterov n = find_node_in_range(inode, min, max); 983891c3970SOleg Nesterov if (n) { 984891c3970SOleg Nesterov for (t = n; t; t = rb_prev(t)) { 985891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 986891c3970SOleg Nesterov if (u->inode != inode || u->offset < min) 987a5f4374aSIngo Molnar break; 988891c3970SOleg Nesterov list_add(&u->pending_list, head); 989891c3970SOleg Nesterov atomic_inc(&u->ref); 990a5f4374aSIngo Molnar } 991891c3970SOleg Nesterov for (t = n; (t = rb_next(t)); ) { 992891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 993891c3970SOleg Nesterov if (u->inode != inode || u->offset > max) 994891c3970SOleg Nesterov break; 995891c3970SOleg Nesterov list_add(&u->pending_list, head); 996891c3970SOleg Nesterov atomic_inc(&u->ref); 997891c3970SOleg Nesterov } 998891c3970SOleg Nesterov } 9996f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 1000a5f4374aSIngo Molnar } 1001a5f4374aSIngo Molnar 1002a5f4374aSIngo Molnar /* 10035e5be71aSOleg Nesterov * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. 1004a5f4374aSIngo Molnar * 10055e5be71aSOleg Nesterov * Currently we ignore all errors and always return 0, the callers 10065e5be71aSOleg Nesterov * can't handle the failure anyway. 1007a5f4374aSIngo Molnar */ 1008a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1009a5f4374aSIngo Molnar { 1010a5f4374aSIngo Molnar struct list_head tmp_list; 1011665605a2SOleg Nesterov struct uprobe *uprobe, *u; 1012a5f4374aSIngo Molnar struct inode *inode; 1013a5f4374aSIngo Molnar 1014a5f4374aSIngo Molnar if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) 1015a5f4374aSIngo Molnar return 0; 1016a5f4374aSIngo Molnar 1017a5f4374aSIngo Molnar inode = vma->vm_file->f_mapping->host; 1018a5f4374aSIngo Molnar if (!inode) 1019a5f4374aSIngo Molnar return 0; 1020a5f4374aSIngo Molnar 1021a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1022891c3970SOleg Nesterov build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); 1023a5f4374aSIngo Molnar 1024665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 10255e5be71aSOleg Nesterov if (!fatal_signal_pending(current)) { 102657683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 10275e5be71aSOleg Nesterov install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1028a5f4374aSIngo Molnar } 1029a5f4374aSIngo Molnar put_uprobe(uprobe); 1030a5f4374aSIngo Molnar } 1031a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1032a5f4374aSIngo Molnar 10335e5be71aSOleg Nesterov return 0; 1034a5f4374aSIngo Molnar } 1035a5f4374aSIngo Molnar 10369f68f672SOleg Nesterov static bool 10379f68f672SOleg Nesterov vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) 10389f68f672SOleg Nesterov { 10399f68f672SOleg Nesterov loff_t min, max; 10409f68f672SOleg Nesterov struct inode *inode; 10419f68f672SOleg Nesterov struct rb_node *n; 10429f68f672SOleg Nesterov 10439f68f672SOleg Nesterov inode = vma->vm_file->f_mapping->host; 10449f68f672SOleg Nesterov 10459f68f672SOleg Nesterov min = vaddr_to_offset(vma, start); 10469f68f672SOleg Nesterov max = min + (end - start) - 1; 10479f68f672SOleg Nesterov 10489f68f672SOleg Nesterov spin_lock(&uprobes_treelock); 10499f68f672SOleg Nesterov n = find_node_in_range(inode, min, max); 10509f68f672SOleg Nesterov spin_unlock(&uprobes_treelock); 10519f68f672SOleg Nesterov 10529f68f672SOleg Nesterov return !!n; 10539f68f672SOleg Nesterov } 10549f68f672SOleg Nesterov 1055682968e0SSrikar Dronamraju /* 1056682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1057682968e0SSrikar Dronamraju */ 1058cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1059682968e0SSrikar Dronamraju { 1060682968e0SSrikar Dronamraju if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) 1061682968e0SSrikar Dronamraju return; 1062682968e0SSrikar Dronamraju 10632fd611a9SOleg Nesterov if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ 10642fd611a9SOleg Nesterov return; 10652fd611a9SOleg Nesterov 10669f68f672SOleg Nesterov if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || 10679f68f672SOleg Nesterov test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) 1068f8ac4ec9SOleg Nesterov return; 1069f8ac4ec9SOleg Nesterov 10709f68f672SOleg Nesterov if (vma_has_uprobes(vma, start, end)) 10719f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); 1072682968e0SSrikar Dronamraju } 1073682968e0SSrikar Dronamraju 1074d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 1075d4b3b638SSrikar Dronamraju static int xol_add_vma(struct xol_area *area) 1076d4b3b638SSrikar Dronamraju { 1077d4b3b638SSrikar Dronamraju struct mm_struct *mm; 1078d4b3b638SSrikar Dronamraju int ret; 1079d4b3b638SSrikar Dronamraju 1080d4b3b638SSrikar Dronamraju area->page = alloc_page(GFP_HIGHUSER); 1081d4b3b638SSrikar Dronamraju if (!area->page) 1082d4b3b638SSrikar Dronamraju return -ENOMEM; 1083d4b3b638SSrikar Dronamraju 1084d4b3b638SSrikar Dronamraju ret = -EALREADY; 1085d4b3b638SSrikar Dronamraju mm = current->mm; 1086d4b3b638SSrikar Dronamraju 1087d4b3b638SSrikar Dronamraju down_write(&mm->mmap_sem); 1088d4b3b638SSrikar Dronamraju if (mm->uprobes_state.xol_area) 1089d4b3b638SSrikar Dronamraju goto fail; 1090d4b3b638SSrikar Dronamraju 1091d4b3b638SSrikar Dronamraju ret = -ENOMEM; 1092d4b3b638SSrikar Dronamraju 1093d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1094d4b3b638SSrikar Dronamraju area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); 1095d4b3b638SSrikar Dronamraju if (area->vaddr & ~PAGE_MASK) { 1096d4b3b638SSrikar Dronamraju ret = area->vaddr; 1097d4b3b638SSrikar Dronamraju goto fail; 1098d4b3b638SSrikar Dronamraju } 1099d4b3b638SSrikar Dronamraju 1100d4b3b638SSrikar Dronamraju ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1101d4b3b638SSrikar Dronamraju VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); 1102d4b3b638SSrikar Dronamraju if (ret) 1103d4b3b638SSrikar Dronamraju goto fail; 1104d4b3b638SSrikar Dronamraju 1105d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1106d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1107d4b3b638SSrikar Dronamraju ret = 0; 1108d4b3b638SSrikar Dronamraju 1109d4b3b638SSrikar Dronamraju fail: 1110d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1111d4b3b638SSrikar Dronamraju if (ret) 1112d4b3b638SSrikar Dronamraju __free_page(area->page); 1113d4b3b638SSrikar Dronamraju 1114d4b3b638SSrikar Dronamraju return ret; 1115d4b3b638SSrikar Dronamraju } 1116d4b3b638SSrikar Dronamraju 1117d4b3b638SSrikar Dronamraju static struct xol_area *get_xol_area(struct mm_struct *mm) 1118d4b3b638SSrikar Dronamraju { 1119d4b3b638SSrikar Dronamraju struct xol_area *area; 1120d4b3b638SSrikar Dronamraju 1121d4b3b638SSrikar Dronamraju area = mm->uprobes_state.xol_area; 1122d4b3b638SSrikar Dronamraju smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 1123d4b3b638SSrikar Dronamraju 1124d4b3b638SSrikar Dronamraju return area; 1125d4b3b638SSrikar Dronamraju } 1126d4b3b638SSrikar Dronamraju 1127d4b3b638SSrikar Dronamraju /* 1128d4b3b638SSrikar Dronamraju * xol_alloc_area - Allocate process's xol_area. 1129d4b3b638SSrikar Dronamraju * This area will be used for storing instructions for execution out of 1130d4b3b638SSrikar Dronamraju * line. 1131d4b3b638SSrikar Dronamraju * 1132d4b3b638SSrikar Dronamraju * Returns the allocated area or NULL. 1133d4b3b638SSrikar Dronamraju */ 1134d4b3b638SSrikar Dronamraju static struct xol_area *xol_alloc_area(void) 1135d4b3b638SSrikar Dronamraju { 1136d4b3b638SSrikar Dronamraju struct xol_area *area; 1137d4b3b638SSrikar Dronamraju 1138d4b3b638SSrikar Dronamraju area = kzalloc(sizeof(*area), GFP_KERNEL); 1139d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1140d4b3b638SSrikar Dronamraju return NULL; 1141d4b3b638SSrikar Dronamraju 1142d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1143d4b3b638SSrikar Dronamraju 1144d4b3b638SSrikar Dronamraju if (!area->bitmap) 1145d4b3b638SSrikar Dronamraju goto fail; 1146d4b3b638SSrikar Dronamraju 1147d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 1148d4b3b638SSrikar Dronamraju if (!xol_add_vma(area)) 1149d4b3b638SSrikar Dronamraju return area; 1150d4b3b638SSrikar Dronamraju 1151d4b3b638SSrikar Dronamraju fail: 1152d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1153d4b3b638SSrikar Dronamraju kfree(area); 1154d4b3b638SSrikar Dronamraju 1155d4b3b638SSrikar Dronamraju return get_xol_area(current->mm); 1156d4b3b638SSrikar Dronamraju } 1157d4b3b638SSrikar Dronamraju 1158d4b3b638SSrikar Dronamraju /* 1159d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1160d4b3b638SSrikar Dronamraju */ 1161d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1162d4b3b638SSrikar Dronamraju { 1163d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1164d4b3b638SSrikar Dronamraju 1165d4b3b638SSrikar Dronamraju if (!area) 1166d4b3b638SSrikar Dronamraju return; 1167d4b3b638SSrikar Dronamraju 1168d4b3b638SSrikar Dronamraju put_page(area->page); 1169d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1170d4b3b638SSrikar Dronamraju kfree(area); 1171d4b3b638SSrikar Dronamraju } 1172d4b3b638SSrikar Dronamraju 1173f8ac4ec9SOleg Nesterov void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) 1174f8ac4ec9SOleg Nesterov { 117561559a81SOleg Nesterov newmm->uprobes_state.xol_area = NULL; 117661559a81SOleg Nesterov 11779f68f672SOleg Nesterov if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { 1178f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &newmm->flags); 11799f68f672SOleg Nesterov /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ 11809f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &newmm->flags); 11819f68f672SOleg Nesterov } 1182f8ac4ec9SOleg Nesterov } 1183f8ac4ec9SOleg Nesterov 1184d4b3b638SSrikar Dronamraju /* 1185d4b3b638SSrikar Dronamraju * - search for a free slot. 1186d4b3b638SSrikar Dronamraju */ 1187d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1188d4b3b638SSrikar Dronamraju { 1189d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1190d4b3b638SSrikar Dronamraju int slot_nr; 1191d4b3b638SSrikar Dronamraju 1192d4b3b638SSrikar Dronamraju do { 1193d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1194d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1195d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1196d4b3b638SSrikar Dronamraju break; 1197d4b3b638SSrikar Dronamraju 1198d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1199d4b3b638SSrikar Dronamraju continue; 1200d4b3b638SSrikar Dronamraju } 1201d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1202d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1203d4b3b638SSrikar Dronamraju 1204d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1205d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1206d4b3b638SSrikar Dronamraju 1207d4b3b638SSrikar Dronamraju return slot_addr; 1208d4b3b638SSrikar Dronamraju } 1209d4b3b638SSrikar Dronamraju 1210d4b3b638SSrikar Dronamraju /* 1211d4b3b638SSrikar Dronamraju * xol_get_insn_slot - If was not allocated a slot, then 1212d4b3b638SSrikar Dronamraju * allocate a slot. 1213d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1214d4b3b638SSrikar Dronamraju */ 1215d4b3b638SSrikar Dronamraju static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot_addr) 1216d4b3b638SSrikar Dronamraju { 1217d4b3b638SSrikar Dronamraju struct xol_area *area; 1218d4b3b638SSrikar Dronamraju unsigned long offset; 1219d4b3b638SSrikar Dronamraju void *vaddr; 1220d4b3b638SSrikar Dronamraju 1221d4b3b638SSrikar Dronamraju area = get_xol_area(current->mm); 1222d4b3b638SSrikar Dronamraju if (!area) { 1223d4b3b638SSrikar Dronamraju area = xol_alloc_area(); 1224d4b3b638SSrikar Dronamraju if (!area) 1225d4b3b638SSrikar Dronamraju return 0; 1226d4b3b638SSrikar Dronamraju } 1227d4b3b638SSrikar Dronamraju current->utask->xol_vaddr = xol_take_insn_slot(area); 1228d4b3b638SSrikar Dronamraju 1229d4b3b638SSrikar Dronamraju /* 1230d4b3b638SSrikar Dronamraju * Initialize the slot if xol_vaddr points to valid 1231d4b3b638SSrikar Dronamraju * instruction slot. 1232d4b3b638SSrikar Dronamraju */ 1233d4b3b638SSrikar Dronamraju if (unlikely(!current->utask->xol_vaddr)) 1234d4b3b638SSrikar Dronamraju return 0; 1235d4b3b638SSrikar Dronamraju 1236d4b3b638SSrikar Dronamraju current->utask->vaddr = slot_addr; 1237d4b3b638SSrikar Dronamraju offset = current->utask->xol_vaddr & ~PAGE_MASK; 1238d4b3b638SSrikar Dronamraju vaddr = kmap_atomic(area->page); 1239d4b3b638SSrikar Dronamraju memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); 1240d4b3b638SSrikar Dronamraju kunmap_atomic(vaddr); 1241d4b3b638SSrikar Dronamraju 1242d4b3b638SSrikar Dronamraju return current->utask->xol_vaddr; 1243d4b3b638SSrikar Dronamraju } 1244d4b3b638SSrikar Dronamraju 1245d4b3b638SSrikar Dronamraju /* 1246d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1247d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1248d4b3b638SSrikar Dronamraju * subsequent requests. 1249d4b3b638SSrikar Dronamraju */ 1250d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1251d4b3b638SSrikar Dronamraju { 1252d4b3b638SSrikar Dronamraju struct xol_area *area; 1253d4b3b638SSrikar Dronamraju unsigned long vma_end; 1254d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1255d4b3b638SSrikar Dronamraju 1256d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1257d4b3b638SSrikar Dronamraju return; 1258d4b3b638SSrikar Dronamraju 1259d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1260d4b3b638SSrikar Dronamraju 1261d4b3b638SSrikar Dronamraju if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) 1262d4b3b638SSrikar Dronamraju return; 1263d4b3b638SSrikar Dronamraju 1264d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1265d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1266d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1267d4b3b638SSrikar Dronamraju unsigned long offset; 1268d4b3b638SSrikar Dronamraju int slot_nr; 1269d4b3b638SSrikar Dronamraju 1270d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1271d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1272d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1273d4b3b638SSrikar Dronamraju return; 1274d4b3b638SSrikar Dronamraju 1275d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1276d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 1277d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1278d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1279d4b3b638SSrikar Dronamraju 1280d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1281d4b3b638SSrikar Dronamraju } 1282d4b3b638SSrikar Dronamraju } 1283d4b3b638SSrikar Dronamraju 12840326f5a9SSrikar Dronamraju /** 12850326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 12860326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 12870326f5a9SSrikar Dronamraju * instruction. 12880326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 12890326f5a9SSrikar Dronamraju */ 12900326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 12910326f5a9SSrikar Dronamraju { 12920326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 12930326f5a9SSrikar Dronamraju } 12940326f5a9SSrikar Dronamraju 12950326f5a9SSrikar Dronamraju /* 12960326f5a9SSrikar Dronamraju * Called with no locks held. 12970326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 12980326f5a9SSrikar Dronamraju */ 12990326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 13000326f5a9SSrikar Dronamraju { 13010326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13020326f5a9SSrikar Dronamraju 13030326f5a9SSrikar Dronamraju if (!utask) 13040326f5a9SSrikar Dronamraju return; 13050326f5a9SSrikar Dronamraju 13060326f5a9SSrikar Dronamraju if (utask->active_uprobe) 13070326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 13080326f5a9SSrikar Dronamraju 1309d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 13100326f5a9SSrikar Dronamraju kfree(utask); 13110326f5a9SSrikar Dronamraju t->utask = NULL; 13120326f5a9SSrikar Dronamraju } 13130326f5a9SSrikar Dronamraju 13140326f5a9SSrikar Dronamraju /* 13150326f5a9SSrikar Dronamraju * Called in context of a new clone/fork from copy_process. 13160326f5a9SSrikar Dronamraju */ 13170326f5a9SSrikar Dronamraju void uprobe_copy_process(struct task_struct *t) 13180326f5a9SSrikar Dronamraju { 13190326f5a9SSrikar Dronamraju t->utask = NULL; 13200326f5a9SSrikar Dronamraju } 13210326f5a9SSrikar Dronamraju 13220326f5a9SSrikar Dronamraju /* 13230326f5a9SSrikar Dronamraju * Allocate a uprobe_task object for the task. 13240326f5a9SSrikar Dronamraju * Called when the thread hits a breakpoint for the first time. 13250326f5a9SSrikar Dronamraju * 13260326f5a9SSrikar Dronamraju * Returns: 13270326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 13280326f5a9SSrikar Dronamraju * - NULL otherwise 13290326f5a9SSrikar Dronamraju */ 13300326f5a9SSrikar Dronamraju static struct uprobe_task *add_utask(void) 13310326f5a9SSrikar Dronamraju { 13320326f5a9SSrikar Dronamraju struct uprobe_task *utask; 13330326f5a9SSrikar Dronamraju 13340326f5a9SSrikar Dronamraju utask = kzalloc(sizeof *utask, GFP_KERNEL); 13350326f5a9SSrikar Dronamraju if (unlikely(!utask)) 13360326f5a9SSrikar Dronamraju return NULL; 13370326f5a9SSrikar Dronamraju 13380326f5a9SSrikar Dronamraju current->utask = utask; 13390326f5a9SSrikar Dronamraju return utask; 13400326f5a9SSrikar Dronamraju } 13410326f5a9SSrikar Dronamraju 13420326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 13430326f5a9SSrikar Dronamraju static int 13440326f5a9SSrikar Dronamraju pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long vaddr) 13450326f5a9SSrikar Dronamraju { 1346d4b3b638SSrikar Dronamraju if (xol_get_insn_slot(uprobe, vaddr) && !arch_uprobe_pre_xol(&uprobe->arch, regs)) 1347d4b3b638SSrikar Dronamraju return 0; 1348d4b3b638SSrikar Dronamraju 13490326f5a9SSrikar Dronamraju return -EFAULT; 13500326f5a9SSrikar Dronamraju } 13510326f5a9SSrikar Dronamraju 13520326f5a9SSrikar Dronamraju /* 13530326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 13540326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 13550326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 13560326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 13570326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 13580326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 13590326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 13600326f5a9SSrikar Dronamraju */ 13610326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 13620326f5a9SSrikar Dronamraju { 13630326f5a9SSrikar Dronamraju struct task_struct *t = current; 13640326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13650326f5a9SSrikar Dronamraju 13660326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 13670326f5a9SSrikar Dronamraju return false; 13680326f5a9SSrikar Dronamraju 13690326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 13700326f5a9SSrikar Dronamraju 13710326f5a9SSrikar Dronamraju if (signal_pending(t)) { 13720326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 13730326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 13740326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 13750326f5a9SSrikar Dronamraju 13760326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 13770326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 13780326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 13790326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); 13800326f5a9SSrikar Dronamraju } 13810326f5a9SSrikar Dronamraju } 13820326f5a9SSrikar Dronamraju 13830326f5a9SSrikar Dronamraju return true; 13840326f5a9SSrikar Dronamraju } 13850326f5a9SSrikar Dronamraju 13860326f5a9SSrikar Dronamraju /* 13870326f5a9SSrikar Dronamraju * Avoid singlestepping the original instruction if the original instruction 13880326f5a9SSrikar Dronamraju * is a NOP or can be emulated. 13890326f5a9SSrikar Dronamraju */ 13900326f5a9SSrikar Dronamraju static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) 13910326f5a9SSrikar Dronamraju { 13920326f5a9SSrikar Dronamraju if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 13930326f5a9SSrikar Dronamraju return true; 13940326f5a9SSrikar Dronamraju 13950326f5a9SSrikar Dronamraju uprobe->flags &= ~UPROBE_SKIP_SSTEP; 13960326f5a9SSrikar Dronamraju return false; 13970326f5a9SSrikar Dronamraju } 13980326f5a9SSrikar Dronamraju 1399499a4f3eSOleg Nesterov static void mmf_recalc_uprobes(struct mm_struct *mm) 1400499a4f3eSOleg Nesterov { 1401499a4f3eSOleg Nesterov struct vm_area_struct *vma; 1402499a4f3eSOleg Nesterov 1403499a4f3eSOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 1404499a4f3eSOleg Nesterov if (!valid_vma(vma, false)) 1405499a4f3eSOleg Nesterov continue; 1406499a4f3eSOleg Nesterov /* 1407499a4f3eSOleg Nesterov * This is not strictly accurate, we can race with 1408499a4f3eSOleg Nesterov * uprobe_unregister() and see the already removed 1409499a4f3eSOleg Nesterov * uprobe if delete_uprobe() was not yet called. 1410499a4f3eSOleg Nesterov */ 1411499a4f3eSOleg Nesterov if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) 1412499a4f3eSOleg Nesterov return; 1413499a4f3eSOleg Nesterov } 1414499a4f3eSOleg Nesterov 1415499a4f3eSOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 1416499a4f3eSOleg Nesterov } 1417499a4f3eSOleg Nesterov 1418d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 14190326f5a9SSrikar Dronamraju { 14203a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 14213a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 14220326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 14230326f5a9SSrikar Dronamraju 14240326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 14250326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 14263a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 14273a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 1428cb113b47SOleg Nesterov struct inode *inode = vma->vm_file->f_mapping->host; 1429cb113b47SOleg Nesterov loff_t offset = vaddr_to_offset(vma, bp_vaddr); 14300326f5a9SSrikar Dronamraju 14310326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 14320326f5a9SSrikar Dronamraju } 1433d790d346SOleg Nesterov 1434d790d346SOleg Nesterov if (!uprobe) 1435d790d346SOleg Nesterov *is_swbp = is_swbp_at_addr(mm, bp_vaddr); 1436d790d346SOleg Nesterov } else { 1437d790d346SOleg Nesterov *is_swbp = -EFAULT; 14383a9ea052SOleg Nesterov } 1439499a4f3eSOleg Nesterov 1440499a4f3eSOleg Nesterov if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) 1441499a4f3eSOleg Nesterov mmf_recalc_uprobes(mm); 14420326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 14430326f5a9SSrikar Dronamraju 14443a9ea052SOleg Nesterov return uprobe; 14453a9ea052SOleg Nesterov } 14463a9ea052SOleg Nesterov 14479d778782SSebastian Andrzej Siewior void __weak arch_uprobe_enable_step(struct arch_uprobe *arch) 14489d778782SSebastian Andrzej Siewior { 14499d778782SSebastian Andrzej Siewior user_enable_single_step(current); 14509d778782SSebastian Andrzej Siewior } 14519d778782SSebastian Andrzej Siewior 14529d778782SSebastian Andrzej Siewior void __weak arch_uprobe_disable_step(struct arch_uprobe *arch) 14539d778782SSebastian Andrzej Siewior { 14549d778782SSebastian Andrzej Siewior user_disable_single_step(current); 14559d778782SSebastian Andrzej Siewior } 14569d778782SSebastian Andrzej Siewior 14573a9ea052SOleg Nesterov /* 14583a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 14593a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 14603a9ea052SOleg Nesterov */ 14613a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 14623a9ea052SOleg Nesterov { 14633a9ea052SOleg Nesterov struct uprobe_task *utask; 14643a9ea052SOleg Nesterov struct uprobe *uprobe; 14653a9ea052SOleg Nesterov unsigned long bp_vaddr; 146656bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 14673a9ea052SOleg Nesterov 14683a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 1469d790d346SOleg Nesterov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 14703a9ea052SOleg Nesterov 14710326f5a9SSrikar Dronamraju if (!uprobe) { 147256bb4cf6SOleg Nesterov if (is_swbp > 0) { 14730326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 14740326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 147556bb4cf6SOleg Nesterov } else { 147656bb4cf6SOleg Nesterov /* 147756bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 147856bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 147956bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 148056bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 148156bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 148256bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 148356bb4cf6SOleg Nesterov */ 148456bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 148556bb4cf6SOleg Nesterov } 14860326f5a9SSrikar Dronamraju return; 14870326f5a9SSrikar Dronamraju } 14880326f5a9SSrikar Dronamraju 14890326f5a9SSrikar Dronamraju utask = current->utask; 14900326f5a9SSrikar Dronamraju if (!utask) { 14910326f5a9SSrikar Dronamraju utask = add_utask(); 14920326f5a9SSrikar Dronamraju /* Cannot allocate; re-execute the instruction. */ 14930326f5a9SSrikar Dronamraju if (!utask) 14940326f5a9SSrikar Dronamraju goto cleanup_ret; 14950326f5a9SSrikar Dronamraju } 14960326f5a9SSrikar Dronamraju utask->active_uprobe = uprobe; 14970326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 14980326f5a9SSrikar Dronamraju if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs)) 14990326f5a9SSrikar Dronamraju goto cleanup_ret; 15000326f5a9SSrikar Dronamraju 15010326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP; 15020326f5a9SSrikar Dronamraju if (!pre_ssout(uprobe, regs, bp_vaddr)) { 15039d778782SSebastian Andrzej Siewior arch_uprobe_enable_step(&uprobe->arch); 15040326f5a9SSrikar Dronamraju return; 15050326f5a9SSrikar Dronamraju } 15060326f5a9SSrikar Dronamraju 15070326f5a9SSrikar Dronamraju cleanup_ret: 15080326f5a9SSrikar Dronamraju if (utask) { 15090326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15100326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 15110326f5a9SSrikar Dronamraju } 15120326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_SKIP_SSTEP)) 15130326f5a9SSrikar Dronamraju 15140326f5a9SSrikar Dronamraju /* 15150326f5a9SSrikar Dronamraju * cannot singlestep; cannot skip instruction; 15160326f5a9SSrikar Dronamraju * re-execute the instruction. 15170326f5a9SSrikar Dronamraju */ 15180326f5a9SSrikar Dronamraju instruction_pointer_set(regs, bp_vaddr); 15190326f5a9SSrikar Dronamraju 15200326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15210326f5a9SSrikar Dronamraju } 15220326f5a9SSrikar Dronamraju 15230326f5a9SSrikar Dronamraju /* 15240326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 15250326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 15260326f5a9SSrikar Dronamraju */ 15270326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 15280326f5a9SSrikar Dronamraju { 15290326f5a9SSrikar Dronamraju struct uprobe *uprobe; 15300326f5a9SSrikar Dronamraju 15310326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 15320326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 15330326f5a9SSrikar Dronamraju arch_uprobe_post_xol(&uprobe->arch, regs); 15340326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 15350326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 15360326f5a9SSrikar Dronamraju else 15370326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 15380326f5a9SSrikar Dronamraju 15399d778782SSebastian Andrzej Siewior arch_uprobe_disable_step(&uprobe->arch); 15400326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15410326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15420326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 1543d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 15440326f5a9SSrikar Dronamraju 15450326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 15460326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 15470326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 15480326f5a9SSrikar Dronamraju } 15490326f5a9SSrikar Dronamraju 15500326f5a9SSrikar Dronamraju /* 15510326f5a9SSrikar Dronamraju * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag. (and on 15520326f5a9SSrikar Dronamraju * subsequent probe hits on the thread sets the state to UTASK_BP_HIT) and 15530326f5a9SSrikar Dronamraju * allows the thread to return from interrupt. 15540326f5a9SSrikar Dronamraju * 15550326f5a9SSrikar Dronamraju * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag and 15560326f5a9SSrikar Dronamraju * also sets the state to UTASK_SSTEP_ACK and allows the thread to return from 15570326f5a9SSrikar Dronamraju * interrupt. 15580326f5a9SSrikar Dronamraju * 15590326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 15600326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 15610326f5a9SSrikar Dronamraju */ 15620326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 15630326f5a9SSrikar Dronamraju { 15640326f5a9SSrikar Dronamraju struct uprobe_task *utask; 15650326f5a9SSrikar Dronamraju 15660326f5a9SSrikar Dronamraju utask = current->utask; 15670326f5a9SSrikar Dronamraju if (!utask || utask->state == UTASK_BP_HIT) 15680326f5a9SSrikar Dronamraju handle_swbp(regs); 15690326f5a9SSrikar Dronamraju else 15700326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 15710326f5a9SSrikar Dronamraju } 15720326f5a9SSrikar Dronamraju 15730326f5a9SSrikar Dronamraju /* 15740326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 15750326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 15760326f5a9SSrikar Dronamraju */ 15770326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 15780326f5a9SSrikar Dronamraju { 15790326f5a9SSrikar Dronamraju struct uprobe_task *utask; 15800326f5a9SSrikar Dronamraju 1581f8ac4ec9SOleg Nesterov if (!current->mm || !test_bit(MMF_HAS_UPROBES, ¤t->mm->flags)) 15820326f5a9SSrikar Dronamraju return 0; 15830326f5a9SSrikar Dronamraju 15840326f5a9SSrikar Dronamraju utask = current->utask; 15850326f5a9SSrikar Dronamraju if (utask) 15860326f5a9SSrikar Dronamraju utask->state = UTASK_BP_HIT; 15870326f5a9SSrikar Dronamraju 15880326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 15890326f5a9SSrikar Dronamraju 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 1619a5f4374aSIngo Molnar for (i = 0; i < UPROBES_HASH_SZ; i++) { 1620a5f4374aSIngo Molnar mutex_init(&uprobes_mutex[i]); 1621a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 1622a5f4374aSIngo Molnar } 16230326f5a9SSrikar Dronamraju 16240326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 1625a5f4374aSIngo Molnar } 16260326f5a9SSrikar Dronamraju module_init(init_uprobes); 1627a5f4374aSIngo Molnar 1628a5f4374aSIngo Molnar static void __exit exit_uprobes(void) 1629a5f4374aSIngo Molnar { 1630a5f4374aSIngo Molnar } 1631a5f4374aSIngo Molnar module_exit(exit_uprobes); 1632