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 lock_page(page); 284a5f4374aSIngo Molnar vaddr_new = kmap_atomic(page); 285a5f4374aSIngo Molnar vaddr &= ~PAGE_MASK; 2865cb4ac3aSSrikar Dronamraju memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE); 287a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 288a5f4374aSIngo Molnar unlock_page(page); 289a5f4374aSIngo Molnar 290a5f4374aSIngo Molnar put_page(page); 291a5f4374aSIngo Molnar 292a5f4374aSIngo Molnar return 0; 293a5f4374aSIngo Molnar } 294a5f4374aSIngo Molnar 2955cb4ac3aSSrikar Dronamraju static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) 296a5f4374aSIngo Molnar { 297a5f4374aSIngo Molnar uprobe_opcode_t opcode; 298a5f4374aSIngo Molnar int result; 299a5f4374aSIngo Molnar 300c00b2750SOleg Nesterov if (current->mm == mm) { 301c00b2750SOleg Nesterov pagefault_disable(); 302c00b2750SOleg Nesterov result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, 303c00b2750SOleg Nesterov sizeof(opcode)); 304c00b2750SOleg Nesterov pagefault_enable(); 305c00b2750SOleg Nesterov 306c00b2750SOleg Nesterov if (likely(result == 0)) 307c00b2750SOleg Nesterov goto out; 308c00b2750SOleg Nesterov } 309c00b2750SOleg Nesterov 310a5f4374aSIngo Molnar result = read_opcode(mm, vaddr, &opcode); 311a5f4374aSIngo Molnar if (result) 312a5f4374aSIngo Molnar return result; 313c00b2750SOleg Nesterov out: 3145cb4ac3aSSrikar Dronamraju if (is_swbp_insn(&opcode)) 315a5f4374aSIngo Molnar return 1; 316a5f4374aSIngo Molnar 317a5f4374aSIngo Molnar return 0; 318a5f4374aSIngo Molnar } 319a5f4374aSIngo Molnar 320a5f4374aSIngo Molnar /** 3215cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 322e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 323a5f4374aSIngo Molnar * @mm: the probed process address space. 324a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 325a5f4374aSIngo Molnar * 326a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 327a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 328a5f4374aSIngo Molnar */ 3295cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 330a5f4374aSIngo Molnar { 331a5f4374aSIngo Molnar int result; 332c5784de2SPeter Zijlstra /* 333c5784de2SPeter Zijlstra * See the comment near uprobes_hash(). 334c5784de2SPeter Zijlstra */ 3355cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 336a5f4374aSIngo Molnar if (result == 1) 337a5f4374aSIngo Molnar return -EEXIST; 338a5f4374aSIngo Molnar 339a5f4374aSIngo Molnar if (result) 340a5f4374aSIngo Molnar return result; 341a5f4374aSIngo Molnar 3425cb4ac3aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); 343a5f4374aSIngo Molnar } 344a5f4374aSIngo Molnar 345a5f4374aSIngo Molnar /** 346a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 347a5f4374aSIngo Molnar * @mm: the probed process address space. 348e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 349a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 350a5f4374aSIngo Molnar * @verify: if true, verify existance of breakpoint instruction. 351a5f4374aSIngo Molnar * 352a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 353a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 354a5f4374aSIngo Molnar */ 355a5f4374aSIngo Molnar int __weak 356e3343e6aSSrikar Dronamraju set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, bool verify) 357a5f4374aSIngo Molnar { 358a5f4374aSIngo Molnar if (verify) { 359a5f4374aSIngo Molnar int result; 360a5f4374aSIngo Molnar 3615cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 362a5f4374aSIngo Molnar if (!result) 363a5f4374aSIngo Molnar return -EINVAL; 364a5f4374aSIngo Molnar 365a5f4374aSIngo Molnar if (result != 1) 366a5f4374aSIngo Molnar return result; 367a5f4374aSIngo Molnar } 368e3343e6aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); 369a5f4374aSIngo Molnar } 370a5f4374aSIngo Molnar 371a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 372a5f4374aSIngo Molnar { 373a5f4374aSIngo Molnar if (l->inode < r->inode) 374a5f4374aSIngo Molnar return -1; 375a5f4374aSIngo Molnar 376a5f4374aSIngo Molnar if (l->inode > r->inode) 377a5f4374aSIngo Molnar return 1; 378a5f4374aSIngo Molnar 379a5f4374aSIngo Molnar if (l->offset < r->offset) 380a5f4374aSIngo Molnar return -1; 381a5f4374aSIngo Molnar 382a5f4374aSIngo Molnar if (l->offset > r->offset) 383a5f4374aSIngo Molnar return 1; 384a5f4374aSIngo Molnar 385a5f4374aSIngo Molnar return 0; 386a5f4374aSIngo Molnar } 387a5f4374aSIngo Molnar 388a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 389a5f4374aSIngo Molnar { 390a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 391a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 392a5f4374aSIngo Molnar struct uprobe *uprobe; 393a5f4374aSIngo Molnar int match; 394a5f4374aSIngo Molnar 395a5f4374aSIngo Molnar while (n) { 396a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 397a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 398a5f4374aSIngo Molnar if (!match) { 399a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 400a5f4374aSIngo Molnar return uprobe; 401a5f4374aSIngo Molnar } 402a5f4374aSIngo Molnar 403a5f4374aSIngo Molnar if (match < 0) 404a5f4374aSIngo Molnar n = n->rb_left; 405a5f4374aSIngo Molnar else 406a5f4374aSIngo Molnar n = n->rb_right; 407a5f4374aSIngo Molnar } 408a5f4374aSIngo Molnar return NULL; 409a5f4374aSIngo Molnar } 410a5f4374aSIngo Molnar 411a5f4374aSIngo Molnar /* 412a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 413a5f4374aSIngo Molnar * Acquires uprobes_treelock 414a5f4374aSIngo Molnar */ 415a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 416a5f4374aSIngo Molnar { 417a5f4374aSIngo Molnar struct uprobe *uprobe; 418a5f4374aSIngo Molnar unsigned long flags; 419a5f4374aSIngo Molnar 420a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 421a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 422a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 423a5f4374aSIngo Molnar 424a5f4374aSIngo Molnar return uprobe; 425a5f4374aSIngo Molnar } 426a5f4374aSIngo Molnar 427a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 428a5f4374aSIngo Molnar { 429a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 430a5f4374aSIngo Molnar struct rb_node *parent = NULL; 431a5f4374aSIngo Molnar struct uprobe *u; 432a5f4374aSIngo Molnar int match; 433a5f4374aSIngo Molnar 434a5f4374aSIngo Molnar while (*p) { 435a5f4374aSIngo Molnar parent = *p; 436a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 437a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 438a5f4374aSIngo Molnar if (!match) { 439a5f4374aSIngo Molnar atomic_inc(&u->ref); 440a5f4374aSIngo Molnar return u; 441a5f4374aSIngo Molnar } 442a5f4374aSIngo Molnar 443a5f4374aSIngo Molnar if (match < 0) 444a5f4374aSIngo Molnar p = &parent->rb_left; 445a5f4374aSIngo Molnar else 446a5f4374aSIngo Molnar p = &parent->rb_right; 447a5f4374aSIngo Molnar 448a5f4374aSIngo Molnar } 449a5f4374aSIngo Molnar 450a5f4374aSIngo Molnar u = NULL; 451a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 452a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 453a5f4374aSIngo Molnar /* get access + creation ref */ 454a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 455a5f4374aSIngo Molnar 456a5f4374aSIngo Molnar return u; 457a5f4374aSIngo Molnar } 458a5f4374aSIngo Molnar 459a5f4374aSIngo Molnar /* 460a5f4374aSIngo Molnar * Acquire uprobes_treelock. 461a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 462a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 463a5f4374aSIngo Molnar * 464a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 465a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 466a5f4374aSIngo Molnar */ 467a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 468a5f4374aSIngo Molnar { 469a5f4374aSIngo Molnar unsigned long flags; 470a5f4374aSIngo Molnar struct uprobe *u; 471a5f4374aSIngo Molnar 472a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 473a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 474a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 475a5f4374aSIngo Molnar 4760326f5a9SSrikar Dronamraju /* For now assume that the instruction need not be single-stepped */ 4770326f5a9SSrikar Dronamraju uprobe->flags |= UPROBE_SKIP_SSTEP; 4780326f5a9SSrikar Dronamraju 479a5f4374aSIngo Molnar return u; 480a5f4374aSIngo Molnar } 481a5f4374aSIngo Molnar 482a5f4374aSIngo Molnar static void put_uprobe(struct uprobe *uprobe) 483a5f4374aSIngo Molnar { 484a5f4374aSIngo Molnar if (atomic_dec_and_test(&uprobe->ref)) 485a5f4374aSIngo Molnar kfree(uprobe); 486a5f4374aSIngo Molnar } 487a5f4374aSIngo Molnar 488a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 489a5f4374aSIngo Molnar { 490a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 491a5f4374aSIngo Molnar 492a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 493a5f4374aSIngo Molnar if (!uprobe) 494a5f4374aSIngo Molnar return NULL; 495a5f4374aSIngo Molnar 496a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 497a5f4374aSIngo Molnar uprobe->offset = offset; 498a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 499a5f4374aSIngo Molnar 500a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 501a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 502a5f4374aSIngo Molnar 503a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 504a5f4374aSIngo Molnar if (cur_uprobe) { 505a5f4374aSIngo Molnar kfree(uprobe); 506a5f4374aSIngo Molnar uprobe = cur_uprobe; 507a5f4374aSIngo Molnar iput(inode); 508a5f4374aSIngo Molnar } else { 509a5f4374aSIngo Molnar atomic_inc(&uprobe_events); 510a5f4374aSIngo Molnar } 511a5f4374aSIngo Molnar 512a5f4374aSIngo Molnar return uprobe; 513a5f4374aSIngo Molnar } 514a5f4374aSIngo Molnar 5150326f5a9SSrikar Dronamraju static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 5160326f5a9SSrikar Dronamraju { 5170326f5a9SSrikar Dronamraju struct uprobe_consumer *uc; 5180326f5a9SSrikar Dronamraju 5190326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_RUN_HANDLER)) 5200326f5a9SSrikar Dronamraju return; 5210326f5a9SSrikar Dronamraju 5220326f5a9SSrikar Dronamraju down_read(&uprobe->consumer_rwsem); 5230326f5a9SSrikar Dronamraju for (uc = uprobe->consumers; uc; uc = uc->next) { 5240326f5a9SSrikar Dronamraju if (!uc->filter || uc->filter(uc, current)) 5250326f5a9SSrikar Dronamraju uc->handler(uc, regs); 5260326f5a9SSrikar Dronamraju } 5270326f5a9SSrikar Dronamraju up_read(&uprobe->consumer_rwsem); 5280326f5a9SSrikar Dronamraju } 5290326f5a9SSrikar Dronamraju 530a5f4374aSIngo Molnar /* Returns the previous consumer */ 531a5f4374aSIngo Molnar static struct uprobe_consumer * 532e3343e6aSSrikar Dronamraju consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 533a5f4374aSIngo Molnar { 534a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 535e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 536e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 537a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 538a5f4374aSIngo Molnar 539e3343e6aSSrikar Dronamraju return uc->next; 540a5f4374aSIngo Molnar } 541a5f4374aSIngo Molnar 542a5f4374aSIngo Molnar /* 543e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 544e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 545a5f4374aSIngo Molnar * or return false. 546a5f4374aSIngo Molnar */ 547e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 548a5f4374aSIngo Molnar { 549a5f4374aSIngo Molnar struct uprobe_consumer **con; 550a5f4374aSIngo Molnar bool ret = false; 551a5f4374aSIngo Molnar 552a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 553a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 554e3343e6aSSrikar Dronamraju if (*con == uc) { 555e3343e6aSSrikar Dronamraju *con = uc->next; 556a5f4374aSIngo Molnar ret = true; 557a5f4374aSIngo Molnar break; 558a5f4374aSIngo Molnar } 559a5f4374aSIngo Molnar } 560a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 561a5f4374aSIngo Molnar 562a5f4374aSIngo Molnar return ret; 563a5f4374aSIngo Molnar } 564a5f4374aSIngo Molnar 565e3343e6aSSrikar Dronamraju static int 566d436615eSOleg Nesterov __copy_insn(struct address_space *mapping, struct file *filp, char *insn, 567593609a5SOleg Nesterov unsigned long nbytes, loff_t offset) 568a5f4374aSIngo Molnar { 569a5f4374aSIngo Molnar struct page *page; 570a5f4374aSIngo Molnar void *vaddr; 571593609a5SOleg Nesterov unsigned long off; 572593609a5SOleg Nesterov pgoff_t idx; 573a5f4374aSIngo Molnar 574a5f4374aSIngo Molnar if (!filp) 575a5f4374aSIngo Molnar return -EINVAL; 576a5f4374aSIngo Molnar 577cc359d18SOleg Nesterov if (!mapping->a_ops->readpage) 578cc359d18SOleg Nesterov return -EIO; 579cc359d18SOleg Nesterov 580593609a5SOleg Nesterov idx = offset >> PAGE_CACHE_SHIFT; 581593609a5SOleg Nesterov off = offset & ~PAGE_MASK; 582a5f4374aSIngo Molnar 583a5f4374aSIngo Molnar /* 584a5f4374aSIngo Molnar * Ensure that the page that has the original instruction is 585a5f4374aSIngo Molnar * populated and in page-cache. 586a5f4374aSIngo Molnar */ 587a5f4374aSIngo Molnar page = read_mapping_page(mapping, idx, filp); 588a5f4374aSIngo Molnar if (IS_ERR(page)) 589a5f4374aSIngo Molnar return PTR_ERR(page); 590a5f4374aSIngo Molnar 591a5f4374aSIngo Molnar vaddr = kmap_atomic(page); 592593609a5SOleg Nesterov memcpy(insn, vaddr + off, nbytes); 593a5f4374aSIngo Molnar kunmap_atomic(vaddr); 594a5f4374aSIngo Molnar page_cache_release(page); 595a5f4374aSIngo Molnar 596a5f4374aSIngo Molnar return 0; 597a5f4374aSIngo Molnar } 598a5f4374aSIngo Molnar 599d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 600a5f4374aSIngo Molnar { 601a5f4374aSIngo Molnar struct address_space *mapping; 602a5f4374aSIngo Molnar unsigned long nbytes; 603a5f4374aSIngo Molnar int bytes; 604a5f4374aSIngo Molnar 605d436615eSOleg Nesterov nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); 606a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 607a5f4374aSIngo Molnar 608a5f4374aSIngo Molnar /* Instruction at end of binary; copy only available bytes */ 609a5f4374aSIngo Molnar if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) 610a5f4374aSIngo Molnar bytes = uprobe->inode->i_size - uprobe->offset; 611a5f4374aSIngo Molnar else 612a5f4374aSIngo Molnar bytes = MAX_UINSN_BYTES; 613a5f4374aSIngo Molnar 614a5f4374aSIngo Molnar /* Instruction at the page-boundary; copy bytes in second page */ 615a5f4374aSIngo Molnar if (nbytes < bytes) { 616fc36f595SOleg Nesterov int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, 617fc36f595SOleg Nesterov bytes - nbytes, uprobe->offset + nbytes); 618fc36f595SOleg Nesterov if (err) 619fc36f595SOleg Nesterov return err; 620a5f4374aSIngo Molnar bytes = nbytes; 621a5f4374aSIngo Molnar } 622d436615eSOleg Nesterov return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); 623a5f4374aSIngo Molnar } 624a5f4374aSIngo Molnar 625682968e0SSrikar Dronamraju /* 626682968e0SSrikar Dronamraju * How mm->uprobes_state.count gets updated 627682968e0SSrikar Dronamraju * uprobe_mmap() increments the count if 628682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 629682968e0SSrikar Dronamraju * - it cannot add a breakpoint, but sees that there is a underlying 630682968e0SSrikar Dronamraju * breakpoint (via a is_swbp_at_addr()). 631682968e0SSrikar Dronamraju * 632682968e0SSrikar Dronamraju * uprobe_munmap() decrements the count if 633682968e0SSrikar Dronamraju * - it sees a underlying breakpoint, (via is_swbp_at_addr) 634682968e0SSrikar Dronamraju * (Subsequent uprobe_unregister wouldnt find the breakpoint 635682968e0SSrikar Dronamraju * unless a uprobe_mmap kicks in, since the old vma would be 636682968e0SSrikar Dronamraju * dropped just after uprobe_munmap.) 637682968e0SSrikar Dronamraju * 638682968e0SSrikar Dronamraju * uprobe_register increments the count if: 639682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 640682968e0SSrikar Dronamraju * 641682968e0SSrikar Dronamraju * uprobe_unregister decrements the count if: 642682968e0SSrikar Dronamraju * - it sees a underlying breakpoint and removes successfully. 643682968e0SSrikar Dronamraju * (via is_swbp_at_addr) 644682968e0SSrikar Dronamraju * (Subsequent uprobe_munmap wouldnt find the breakpoint 645682968e0SSrikar Dronamraju * since there is no underlying breakpoint after the 646682968e0SSrikar Dronamraju * breakpoint removal.) 647682968e0SSrikar Dronamraju */ 648e3343e6aSSrikar Dronamraju static int 649e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 650816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 651a5f4374aSIngo Molnar { 652a5f4374aSIngo Molnar int ret; 653a5f4374aSIngo Molnar 654a5f4374aSIngo Molnar /* 655a5f4374aSIngo Molnar * If probe is being deleted, unregister thread could be done with 656a5f4374aSIngo Molnar * the vma-rmap-walk through. Adding a probe now can be fatal since 657a5f4374aSIngo Molnar * nobody will be able to cleanup. Also we could be from fork or 658a5f4374aSIngo Molnar * mremap path, where the probe might have already been inserted. 659a5f4374aSIngo Molnar * Hence behave as if probe already existed. 660a5f4374aSIngo Molnar */ 661a5f4374aSIngo Molnar if (!uprobe->consumers) 662a5f4374aSIngo Molnar return -EEXIST; 663a5f4374aSIngo Molnar 664900771a4SSrikar Dronamraju if (!(uprobe->flags & UPROBE_COPY_INSN)) { 665d436615eSOleg Nesterov ret = copy_insn(uprobe, vma->vm_file); 666a5f4374aSIngo Molnar if (ret) 667a5f4374aSIngo Molnar return ret; 668a5f4374aSIngo Molnar 6695cb4ac3aSSrikar Dronamraju if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) 670c1914a09SOleg Nesterov return -ENOTSUPP; 671a5f4374aSIngo Molnar 672816c03fbSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 673a5f4374aSIngo Molnar if (ret) 674a5f4374aSIngo Molnar return ret; 675a5f4374aSIngo Molnar 676d9c4a30eSOleg Nesterov /* write_opcode() assumes we don't cross page boundary */ 677d9c4a30eSOleg Nesterov BUG_ON((uprobe->offset & ~PAGE_MASK) + 678d9c4a30eSOleg Nesterov UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 679d9c4a30eSOleg Nesterov 680900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_COPY_INSN; 681a5f4374aSIngo Molnar } 682682968e0SSrikar Dronamraju 683682968e0SSrikar Dronamraju /* 684682968e0SSrikar Dronamraju * Ideally, should be updating the probe count after the breakpoint 685682968e0SSrikar Dronamraju * has been successfully inserted. However a thread could hit the 686682968e0SSrikar Dronamraju * breakpoint we just inserted even before the probe count is 687682968e0SSrikar Dronamraju * incremented. If this is the first breakpoint placed, breakpoint 688682968e0SSrikar Dronamraju * notifier might ignore uprobes and pass the trap to the thread. 689682968e0SSrikar Dronamraju * Hence increment before and decrement on failure. 690682968e0SSrikar Dronamraju */ 691682968e0SSrikar Dronamraju atomic_inc(&mm->uprobes_state.count); 692816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 693682968e0SSrikar Dronamraju if (ret) 694682968e0SSrikar Dronamraju atomic_dec(&mm->uprobes_state.count); 695a5f4374aSIngo Molnar 696a5f4374aSIngo Molnar return ret; 697a5f4374aSIngo Molnar } 698a5f4374aSIngo Molnar 699e3343e6aSSrikar Dronamraju static void 700816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 701a5f4374aSIngo Molnar { 702816c03fbSOleg Nesterov if (!set_orig_insn(&uprobe->arch, mm, vaddr, true)) 703682968e0SSrikar Dronamraju atomic_dec(&mm->uprobes_state.count); 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 { 713a5f4374aSIngo Molnar unsigned long flags; 714a5f4374aSIngo Molnar 715a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 716a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 717a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 718a5f4374aSIngo Molnar iput(uprobe->inode); 719a5f4374aSIngo Molnar put_uprobe(uprobe); 720a5f4374aSIngo Molnar atomic_dec(&uprobe_events); 721a5f4374aSIngo Molnar } 722a5f4374aSIngo Molnar 72326872090SOleg Nesterov struct map_info { 72426872090SOleg Nesterov struct map_info *next; 72526872090SOleg Nesterov struct mm_struct *mm; 726816c03fbSOleg Nesterov unsigned long vaddr; 72726872090SOleg Nesterov }; 72826872090SOleg Nesterov 72926872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 730a5f4374aSIngo Molnar { 73126872090SOleg Nesterov struct map_info *next = info->next; 73226872090SOleg Nesterov kfree(info); 73326872090SOleg Nesterov return next; 73426872090SOleg Nesterov } 73526872090SOleg Nesterov 73626872090SOleg Nesterov static struct map_info * 73726872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 73826872090SOleg Nesterov { 73926872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 740a5f4374aSIngo Molnar struct prio_tree_iter iter; 741a5f4374aSIngo Molnar struct vm_area_struct *vma; 74226872090SOleg Nesterov struct map_info *curr = NULL; 74326872090SOleg Nesterov struct map_info *prev = NULL; 74426872090SOleg Nesterov struct map_info *info; 74526872090SOleg Nesterov int more = 0; 746a5f4374aSIngo Molnar 74726872090SOleg Nesterov again: 74826872090SOleg Nesterov mutex_lock(&mapping->i_mmap_mutex); 749a5f4374aSIngo Molnar vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 750a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 751a5f4374aSIngo Molnar continue; 752a5f4374aSIngo Molnar 7537a5bfb66SOleg Nesterov if (!prev && !more) { 7547a5bfb66SOleg Nesterov /* 7557a5bfb66SOleg Nesterov * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through 7567a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 7577a5bfb66SOleg Nesterov */ 7587a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 7597a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 7607a5bfb66SOleg Nesterov if (prev) 7617a5bfb66SOleg Nesterov prev->next = NULL; 7627a5bfb66SOleg Nesterov } 76326872090SOleg Nesterov if (!prev) { 76426872090SOleg Nesterov more++; 76526872090SOleg Nesterov continue; 766a5f4374aSIngo Molnar } 767a5f4374aSIngo Molnar 76826872090SOleg Nesterov if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) 76926872090SOleg Nesterov continue; 770a5f4374aSIngo Molnar 77126872090SOleg Nesterov info = prev; 77226872090SOleg Nesterov prev = prev->next; 77326872090SOleg Nesterov info->next = curr; 77426872090SOleg Nesterov curr = info; 77526872090SOleg Nesterov 77626872090SOleg Nesterov info->mm = vma->vm_mm; 77757683f72SOleg Nesterov info->vaddr = offset_to_vaddr(vma, offset); 778a5f4374aSIngo Molnar } 779a5f4374aSIngo Molnar mutex_unlock(&mapping->i_mmap_mutex); 780a5f4374aSIngo Molnar 78126872090SOleg Nesterov if (!more) 78226872090SOleg Nesterov goto out; 783a5f4374aSIngo Molnar 78426872090SOleg Nesterov prev = curr; 78526872090SOleg Nesterov while (curr) { 78626872090SOleg Nesterov mmput(curr->mm); 78726872090SOleg Nesterov curr = curr->next; 78826872090SOleg Nesterov } 78926872090SOleg Nesterov 79026872090SOleg Nesterov do { 79126872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 79226872090SOleg Nesterov if (!info) { 79326872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 79426872090SOleg Nesterov goto out; 79526872090SOleg Nesterov } 79626872090SOleg Nesterov info->next = prev; 79726872090SOleg Nesterov prev = info; 79826872090SOleg Nesterov } while (--more); 79926872090SOleg Nesterov 80026872090SOleg Nesterov goto again; 80126872090SOleg Nesterov out: 80226872090SOleg Nesterov while (prev) 80326872090SOleg Nesterov prev = free_map_info(prev); 80426872090SOleg Nesterov return curr; 805a5f4374aSIngo Molnar } 806a5f4374aSIngo Molnar 807a5f4374aSIngo Molnar static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 808a5f4374aSIngo Molnar { 80926872090SOleg Nesterov struct map_info *info; 81026872090SOleg Nesterov int err = 0; 81126872090SOleg Nesterov 81226872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 81326872090SOleg Nesterov uprobe->offset, is_register); 81426872090SOleg Nesterov if (IS_ERR(info)) 81526872090SOleg Nesterov return PTR_ERR(info); 81626872090SOleg Nesterov 81726872090SOleg Nesterov while (info) { 81826872090SOleg Nesterov struct mm_struct *mm = info->mm; 819a5f4374aSIngo Molnar struct vm_area_struct *vma; 820a5f4374aSIngo Molnar 82126872090SOleg Nesterov if (err) 82226872090SOleg Nesterov goto free; 823a5f4374aSIngo Molnar 82477fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 825f4d6dfe5SOleg Nesterov vma = find_vma(mm, info->vaddr); 826f4d6dfe5SOleg Nesterov if (!vma || !valid_vma(vma, is_register) || 827f4d6dfe5SOleg Nesterov vma->vm_file->f_mapping->host != uprobe->inode) 82826872090SOleg Nesterov goto unlock; 82926872090SOleg Nesterov 830f4d6dfe5SOleg Nesterov if (vma->vm_start > info->vaddr || 831f4d6dfe5SOleg Nesterov vaddr_to_offset(vma, info->vaddr) != uprobe->offset) 83226872090SOleg Nesterov goto unlock; 833a5f4374aSIngo Molnar 834a5f4374aSIngo Molnar if (is_register) { 83526872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 836c5784de2SPeter Zijlstra /* 837c5784de2SPeter Zijlstra * We can race against uprobe_mmap(), see the 838c5784de2SPeter Zijlstra * comment near uprobe_hash(). 839c5784de2SPeter Zijlstra */ 84026872090SOleg Nesterov if (err == -EEXIST) 84126872090SOleg Nesterov err = 0; 84226872090SOleg Nesterov } else { 84326872090SOleg Nesterov remove_breakpoint(uprobe, mm, info->vaddr); 844a5f4374aSIngo Molnar } 84526872090SOleg Nesterov unlock: 84626872090SOleg Nesterov up_write(&mm->mmap_sem); 84726872090SOleg Nesterov free: 84826872090SOleg Nesterov mmput(mm); 84926872090SOleg Nesterov info = free_map_info(info); 850a5f4374aSIngo Molnar } 851a5f4374aSIngo Molnar 85226872090SOleg Nesterov return err; 853a5f4374aSIngo Molnar } 854a5f4374aSIngo Molnar 855a5f4374aSIngo Molnar static int __uprobe_register(struct uprobe *uprobe) 856a5f4374aSIngo Molnar { 857a5f4374aSIngo Molnar return register_for_each_vma(uprobe, true); 858a5f4374aSIngo Molnar } 859a5f4374aSIngo Molnar 860a5f4374aSIngo Molnar static void __uprobe_unregister(struct uprobe *uprobe) 861a5f4374aSIngo Molnar { 862a5f4374aSIngo Molnar if (!register_for_each_vma(uprobe, false)) 863a5f4374aSIngo Molnar delete_uprobe(uprobe); 864a5f4374aSIngo Molnar 865a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 866a5f4374aSIngo Molnar } 867a5f4374aSIngo Molnar 868a5f4374aSIngo Molnar /* 869a5f4374aSIngo Molnar * uprobe_register - register a probe 870a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 871a5f4374aSIngo Molnar * @offset: offset from the start of the file. 872e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 873a5f4374aSIngo Molnar * 874a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 875a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 876a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 877a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 878a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 879e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 880a5f4374aSIngo Molnar * unregisters. 881a5f4374aSIngo Molnar * 882a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 883a5f4374aSIngo Molnar * else return 0 (success) 884a5f4374aSIngo Molnar */ 885e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 886a5f4374aSIngo Molnar { 887a5f4374aSIngo Molnar struct uprobe *uprobe; 888a5f4374aSIngo Molnar int ret; 889a5f4374aSIngo Molnar 890e3343e6aSSrikar Dronamraju if (!inode || !uc || uc->next) 891a5f4374aSIngo Molnar return -EINVAL; 892a5f4374aSIngo Molnar 893a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 894a5f4374aSIngo Molnar return -EINVAL; 895a5f4374aSIngo Molnar 896a5f4374aSIngo Molnar ret = 0; 897a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 898a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 899a5f4374aSIngo Molnar 900e3343e6aSSrikar Dronamraju if (uprobe && !consumer_add(uprobe, uc)) { 901a5f4374aSIngo Molnar ret = __uprobe_register(uprobe); 902a5f4374aSIngo Molnar if (ret) { 903a5f4374aSIngo Molnar uprobe->consumers = NULL; 904a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 905a5f4374aSIngo Molnar } else { 906900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_RUN_HANDLER; 907a5f4374aSIngo Molnar } 908a5f4374aSIngo Molnar } 909a5f4374aSIngo Molnar 910a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 911a5f4374aSIngo Molnar put_uprobe(uprobe); 912a5f4374aSIngo Molnar 913a5f4374aSIngo Molnar return ret; 914a5f4374aSIngo Molnar } 915a5f4374aSIngo Molnar 916a5f4374aSIngo Molnar /* 917a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 918a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 919a5f4374aSIngo Molnar * @offset: offset from the start of the file. 920e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 921a5f4374aSIngo Molnar */ 922e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 923a5f4374aSIngo Molnar { 924a5f4374aSIngo Molnar struct uprobe *uprobe; 925a5f4374aSIngo Molnar 926e3343e6aSSrikar Dronamraju if (!inode || !uc) 927a5f4374aSIngo Molnar return; 928a5f4374aSIngo Molnar 929a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 930a5f4374aSIngo Molnar if (!uprobe) 931a5f4374aSIngo Molnar return; 932a5f4374aSIngo Molnar 933a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 934a5f4374aSIngo Molnar 935e3343e6aSSrikar Dronamraju if (consumer_del(uprobe, uc)) { 936a5f4374aSIngo Molnar if (!uprobe->consumers) { 937a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 938900771a4SSrikar Dronamraju uprobe->flags &= ~UPROBE_RUN_HANDLER; 939a5f4374aSIngo Molnar } 940a5f4374aSIngo Molnar } 941a5f4374aSIngo Molnar 942a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 943a5f4374aSIngo Molnar if (uprobe) 944a5f4374aSIngo Molnar put_uprobe(uprobe); 945a5f4374aSIngo Molnar } 946a5f4374aSIngo Molnar 947891c3970SOleg Nesterov static struct rb_node * 948891c3970SOleg Nesterov find_node_in_range(struct inode *inode, loff_t min, loff_t max) 949a5f4374aSIngo Molnar { 950a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 951a5f4374aSIngo Molnar 952a5f4374aSIngo Molnar while (n) { 953891c3970SOleg Nesterov struct uprobe *u = rb_entry(n, struct uprobe, rb_node); 954a5f4374aSIngo Molnar 955891c3970SOleg Nesterov if (inode < u->inode) { 956a5f4374aSIngo Molnar n = n->rb_left; 957891c3970SOleg Nesterov } else if (inode > u->inode) { 958a5f4374aSIngo Molnar n = n->rb_right; 959891c3970SOleg Nesterov } else { 960891c3970SOleg Nesterov if (max < u->offset) 961891c3970SOleg Nesterov n = n->rb_left; 962891c3970SOleg Nesterov else if (min > u->offset) 963891c3970SOleg Nesterov n = n->rb_right; 964891c3970SOleg Nesterov else 965891c3970SOleg Nesterov break; 966891c3970SOleg Nesterov } 967a5f4374aSIngo Molnar } 968a5f4374aSIngo Molnar 969891c3970SOleg Nesterov return n; 970a5f4374aSIngo Molnar } 971a5f4374aSIngo Molnar 972a5f4374aSIngo Molnar /* 973891c3970SOleg Nesterov * For a given range in vma, build a list of probes that need to be inserted. 974a5f4374aSIngo Molnar */ 975891c3970SOleg Nesterov static void build_probe_list(struct inode *inode, 976891c3970SOleg Nesterov struct vm_area_struct *vma, 977891c3970SOleg Nesterov unsigned long start, unsigned long end, 978891c3970SOleg Nesterov struct list_head *head) 979a5f4374aSIngo Molnar { 980891c3970SOleg Nesterov loff_t min, max; 981a5f4374aSIngo Molnar unsigned long flags; 982891c3970SOleg Nesterov struct rb_node *n, *t; 983891c3970SOleg Nesterov struct uprobe *u; 984891c3970SOleg Nesterov 985891c3970SOleg Nesterov INIT_LIST_HEAD(head); 986cb113b47SOleg Nesterov min = vaddr_to_offset(vma, start); 987891c3970SOleg Nesterov max = min + (end - start) - 1; 988a5f4374aSIngo Molnar 989a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 990891c3970SOleg Nesterov n = find_node_in_range(inode, min, max); 991891c3970SOleg Nesterov if (n) { 992891c3970SOleg Nesterov for (t = n; t; t = rb_prev(t)) { 993891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 994891c3970SOleg Nesterov if (u->inode != inode || u->offset < min) 995a5f4374aSIngo Molnar break; 996891c3970SOleg Nesterov list_add(&u->pending_list, head); 997891c3970SOleg Nesterov atomic_inc(&u->ref); 998a5f4374aSIngo Molnar } 999891c3970SOleg Nesterov for (t = n; (t = rb_next(t)); ) { 1000891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1001891c3970SOleg Nesterov if (u->inode != inode || u->offset > max) 1002891c3970SOleg Nesterov break; 1003891c3970SOleg Nesterov list_add(&u->pending_list, head); 1004891c3970SOleg Nesterov atomic_inc(&u->ref); 1005891c3970SOleg Nesterov } 1006891c3970SOleg Nesterov } 1007a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 1008a5f4374aSIngo Molnar } 1009a5f4374aSIngo Molnar 1010a5f4374aSIngo Molnar /* 1011a5f4374aSIngo Molnar * Called from mmap_region. 1012a5f4374aSIngo Molnar * called with mm->mmap_sem acquired. 1013a5f4374aSIngo Molnar * 1014a5f4374aSIngo Molnar * Return -ve no if we fail to insert probes and we cannot 1015a5f4374aSIngo Molnar * bail-out. 1016a5f4374aSIngo Molnar * Return 0 otherwise. i.e: 1017a5f4374aSIngo Molnar * 1018a5f4374aSIngo Molnar * - successful insertion of probes 1019a5f4374aSIngo Molnar * - (or) no possible probes to be inserted. 1020a5f4374aSIngo Molnar * - (or) insertion of probes failed but we can bail-out. 1021a5f4374aSIngo Molnar */ 1022a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1023a5f4374aSIngo Molnar { 1024a5f4374aSIngo Molnar struct list_head tmp_list; 1025665605a2SOleg Nesterov struct uprobe *uprobe, *u; 1026a5f4374aSIngo Molnar struct inode *inode; 1027682968e0SSrikar Dronamraju int ret, count; 1028a5f4374aSIngo Molnar 1029a5f4374aSIngo Molnar if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) 1030a5f4374aSIngo Molnar return 0; 1031a5f4374aSIngo Molnar 1032a5f4374aSIngo Molnar inode = vma->vm_file->f_mapping->host; 1033a5f4374aSIngo Molnar if (!inode) 1034a5f4374aSIngo Molnar return 0; 1035a5f4374aSIngo Molnar 1036a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1037891c3970SOleg Nesterov build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); 1038a5f4374aSIngo Molnar 1039a5f4374aSIngo Molnar ret = 0; 1040682968e0SSrikar Dronamraju count = 0; 1041a5f4374aSIngo Molnar 1042665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 1043a5f4374aSIngo Molnar if (!ret) { 104457683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 1045682968e0SSrikar Dronamraju 1046682968e0SSrikar Dronamraju ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1047c5784de2SPeter Zijlstra /* 1048c5784de2SPeter Zijlstra * We can race against uprobe_register(), see the 1049c5784de2SPeter Zijlstra * comment near uprobe_hash(). 1050c5784de2SPeter Zijlstra */ 1051682968e0SSrikar Dronamraju if (ret == -EEXIST) { 1052682968e0SSrikar Dronamraju ret = 0; 1053682968e0SSrikar Dronamraju 1054682968e0SSrikar Dronamraju if (!is_swbp_at_addr(vma->vm_mm, vaddr)) 1055682968e0SSrikar Dronamraju continue; 1056682968e0SSrikar Dronamraju 1057682968e0SSrikar Dronamraju /* 1058682968e0SSrikar Dronamraju * Unable to insert a breakpoint, but 1059682968e0SSrikar Dronamraju * breakpoint lies underneath. Increment the 1060682968e0SSrikar Dronamraju * probe count. 1061682968e0SSrikar Dronamraju */ 1062682968e0SSrikar Dronamraju atomic_inc(&vma->vm_mm->uprobes_state.count); 1063682968e0SSrikar Dronamraju } 1064682968e0SSrikar Dronamraju 1065682968e0SSrikar Dronamraju if (!ret) 1066682968e0SSrikar Dronamraju count++; 1067a5f4374aSIngo Molnar } 1068a5f4374aSIngo Molnar put_uprobe(uprobe); 1069a5f4374aSIngo Molnar } 1070a5f4374aSIngo Molnar 1071a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1072a5f4374aSIngo Molnar 1073682968e0SSrikar Dronamraju if (ret) 1074682968e0SSrikar Dronamraju atomic_sub(count, &vma->vm_mm->uprobes_state.count); 1075682968e0SSrikar Dronamraju 1076a5f4374aSIngo Molnar return ret; 1077a5f4374aSIngo Molnar } 1078a5f4374aSIngo Molnar 1079682968e0SSrikar Dronamraju /* 1080682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1081682968e0SSrikar Dronamraju */ 1082cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1083682968e0SSrikar Dronamraju { 1084682968e0SSrikar Dronamraju struct list_head tmp_list; 1085665605a2SOleg Nesterov struct uprobe *uprobe, *u; 1086682968e0SSrikar Dronamraju struct inode *inode; 1087682968e0SSrikar Dronamraju 1088682968e0SSrikar Dronamraju if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) 1089682968e0SSrikar Dronamraju return; 1090682968e0SSrikar Dronamraju 10912fd611a9SOleg Nesterov if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ 10922fd611a9SOleg Nesterov return; 10932fd611a9SOleg Nesterov 1094682968e0SSrikar Dronamraju if (!atomic_read(&vma->vm_mm->uprobes_state.count)) 1095682968e0SSrikar Dronamraju return; 1096682968e0SSrikar Dronamraju 1097682968e0SSrikar Dronamraju inode = vma->vm_file->f_mapping->host; 1098682968e0SSrikar Dronamraju if (!inode) 1099682968e0SSrikar Dronamraju return; 1100682968e0SSrikar Dronamraju 1101682968e0SSrikar Dronamraju mutex_lock(uprobes_mmap_hash(inode)); 1102891c3970SOleg Nesterov build_probe_list(inode, vma, start, end, &tmp_list); 1103682968e0SSrikar Dronamraju 1104665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 110557683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 1106682968e0SSrikar Dronamraju /* 1107682968e0SSrikar Dronamraju * An unregister could have removed the probe before 1108682968e0SSrikar Dronamraju * unmap. So check before we decrement the count. 1109682968e0SSrikar Dronamraju */ 1110682968e0SSrikar Dronamraju if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1) 1111682968e0SSrikar Dronamraju atomic_dec(&vma->vm_mm->uprobes_state.count); 1112682968e0SSrikar Dronamraju put_uprobe(uprobe); 1113682968e0SSrikar Dronamraju } 1114682968e0SSrikar Dronamraju mutex_unlock(uprobes_mmap_hash(inode)); 1115682968e0SSrikar Dronamraju } 1116682968e0SSrikar Dronamraju 1117d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 1118d4b3b638SSrikar Dronamraju static int xol_add_vma(struct xol_area *area) 1119d4b3b638SSrikar Dronamraju { 1120d4b3b638SSrikar Dronamraju struct mm_struct *mm; 1121d4b3b638SSrikar Dronamraju int ret; 1122d4b3b638SSrikar Dronamraju 1123d4b3b638SSrikar Dronamraju area->page = alloc_page(GFP_HIGHUSER); 1124d4b3b638SSrikar Dronamraju if (!area->page) 1125d4b3b638SSrikar Dronamraju return -ENOMEM; 1126d4b3b638SSrikar Dronamraju 1127d4b3b638SSrikar Dronamraju ret = -EALREADY; 1128d4b3b638SSrikar Dronamraju mm = current->mm; 1129d4b3b638SSrikar Dronamraju 1130d4b3b638SSrikar Dronamraju down_write(&mm->mmap_sem); 1131d4b3b638SSrikar Dronamraju if (mm->uprobes_state.xol_area) 1132d4b3b638SSrikar Dronamraju goto fail; 1133d4b3b638SSrikar Dronamraju 1134d4b3b638SSrikar Dronamraju ret = -ENOMEM; 1135d4b3b638SSrikar Dronamraju 1136d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1137d4b3b638SSrikar Dronamraju area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); 1138d4b3b638SSrikar Dronamraju if (area->vaddr & ~PAGE_MASK) { 1139d4b3b638SSrikar Dronamraju ret = area->vaddr; 1140d4b3b638SSrikar Dronamraju goto fail; 1141d4b3b638SSrikar Dronamraju } 1142d4b3b638SSrikar Dronamraju 1143d4b3b638SSrikar Dronamraju ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1144d4b3b638SSrikar Dronamraju VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); 1145d4b3b638SSrikar Dronamraju if (ret) 1146d4b3b638SSrikar Dronamraju goto fail; 1147d4b3b638SSrikar Dronamraju 1148d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1149d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1150d4b3b638SSrikar Dronamraju ret = 0; 1151d4b3b638SSrikar Dronamraju 1152d4b3b638SSrikar Dronamraju fail: 1153d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1154d4b3b638SSrikar Dronamraju if (ret) 1155d4b3b638SSrikar Dronamraju __free_page(area->page); 1156d4b3b638SSrikar Dronamraju 1157d4b3b638SSrikar Dronamraju return ret; 1158d4b3b638SSrikar Dronamraju } 1159d4b3b638SSrikar Dronamraju 1160d4b3b638SSrikar Dronamraju static struct xol_area *get_xol_area(struct mm_struct *mm) 1161d4b3b638SSrikar Dronamraju { 1162d4b3b638SSrikar Dronamraju struct xol_area *area; 1163d4b3b638SSrikar Dronamraju 1164d4b3b638SSrikar Dronamraju area = mm->uprobes_state.xol_area; 1165d4b3b638SSrikar Dronamraju smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 1166d4b3b638SSrikar Dronamraju 1167d4b3b638SSrikar Dronamraju return area; 1168d4b3b638SSrikar Dronamraju } 1169d4b3b638SSrikar Dronamraju 1170d4b3b638SSrikar Dronamraju /* 1171d4b3b638SSrikar Dronamraju * xol_alloc_area - Allocate process's xol_area. 1172d4b3b638SSrikar Dronamraju * This area will be used for storing instructions for execution out of 1173d4b3b638SSrikar Dronamraju * line. 1174d4b3b638SSrikar Dronamraju * 1175d4b3b638SSrikar Dronamraju * Returns the allocated area or NULL. 1176d4b3b638SSrikar Dronamraju */ 1177d4b3b638SSrikar Dronamraju static struct xol_area *xol_alloc_area(void) 1178d4b3b638SSrikar Dronamraju { 1179d4b3b638SSrikar Dronamraju struct xol_area *area; 1180d4b3b638SSrikar Dronamraju 1181d4b3b638SSrikar Dronamraju area = kzalloc(sizeof(*area), GFP_KERNEL); 1182d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1183d4b3b638SSrikar Dronamraju return NULL; 1184d4b3b638SSrikar Dronamraju 1185d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1186d4b3b638SSrikar Dronamraju 1187d4b3b638SSrikar Dronamraju if (!area->bitmap) 1188d4b3b638SSrikar Dronamraju goto fail; 1189d4b3b638SSrikar Dronamraju 1190d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 1191d4b3b638SSrikar Dronamraju if (!xol_add_vma(area)) 1192d4b3b638SSrikar Dronamraju return area; 1193d4b3b638SSrikar Dronamraju 1194d4b3b638SSrikar Dronamraju fail: 1195d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1196d4b3b638SSrikar Dronamraju kfree(area); 1197d4b3b638SSrikar Dronamraju 1198d4b3b638SSrikar Dronamraju return get_xol_area(current->mm); 1199d4b3b638SSrikar Dronamraju } 1200d4b3b638SSrikar Dronamraju 1201d4b3b638SSrikar Dronamraju /* 1202d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1203d4b3b638SSrikar Dronamraju */ 1204d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1205d4b3b638SSrikar Dronamraju { 1206d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1207d4b3b638SSrikar Dronamraju 1208d4b3b638SSrikar Dronamraju if (!area) 1209d4b3b638SSrikar Dronamraju return; 1210d4b3b638SSrikar Dronamraju 1211d4b3b638SSrikar Dronamraju put_page(area->page); 1212d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1213d4b3b638SSrikar Dronamraju kfree(area); 1214d4b3b638SSrikar Dronamraju } 1215d4b3b638SSrikar Dronamraju 1216d4b3b638SSrikar Dronamraju /* 1217d4b3b638SSrikar Dronamraju * uprobe_reset_state - Free the area allocated for slots. 1218d4b3b638SSrikar Dronamraju */ 1219d4b3b638SSrikar Dronamraju void uprobe_reset_state(struct mm_struct *mm) 1220d4b3b638SSrikar Dronamraju { 1221d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = NULL; 1222682968e0SSrikar Dronamraju atomic_set(&mm->uprobes_state.count, 0); 1223d4b3b638SSrikar Dronamraju } 1224d4b3b638SSrikar Dronamraju 1225d4b3b638SSrikar Dronamraju /* 1226d4b3b638SSrikar Dronamraju * - search for a free slot. 1227d4b3b638SSrikar Dronamraju */ 1228d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1229d4b3b638SSrikar Dronamraju { 1230d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1231d4b3b638SSrikar Dronamraju int slot_nr; 1232d4b3b638SSrikar Dronamraju 1233d4b3b638SSrikar Dronamraju do { 1234d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1235d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1236d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1237d4b3b638SSrikar Dronamraju break; 1238d4b3b638SSrikar Dronamraju 1239d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1240d4b3b638SSrikar Dronamraju continue; 1241d4b3b638SSrikar Dronamraju } 1242d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1243d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1244d4b3b638SSrikar Dronamraju 1245d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1246d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1247d4b3b638SSrikar Dronamraju 1248d4b3b638SSrikar Dronamraju return slot_addr; 1249d4b3b638SSrikar Dronamraju } 1250d4b3b638SSrikar Dronamraju 1251d4b3b638SSrikar Dronamraju /* 1252d4b3b638SSrikar Dronamraju * xol_get_insn_slot - If was not allocated a slot, then 1253d4b3b638SSrikar Dronamraju * allocate a slot. 1254d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1255d4b3b638SSrikar Dronamraju */ 1256d4b3b638SSrikar Dronamraju static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot_addr) 1257d4b3b638SSrikar Dronamraju { 1258d4b3b638SSrikar Dronamraju struct xol_area *area; 1259d4b3b638SSrikar Dronamraju unsigned long offset; 1260d4b3b638SSrikar Dronamraju void *vaddr; 1261d4b3b638SSrikar Dronamraju 1262d4b3b638SSrikar Dronamraju area = get_xol_area(current->mm); 1263d4b3b638SSrikar Dronamraju if (!area) { 1264d4b3b638SSrikar Dronamraju area = xol_alloc_area(); 1265d4b3b638SSrikar Dronamraju if (!area) 1266d4b3b638SSrikar Dronamraju return 0; 1267d4b3b638SSrikar Dronamraju } 1268d4b3b638SSrikar Dronamraju current->utask->xol_vaddr = xol_take_insn_slot(area); 1269d4b3b638SSrikar Dronamraju 1270d4b3b638SSrikar Dronamraju /* 1271d4b3b638SSrikar Dronamraju * Initialize the slot if xol_vaddr points to valid 1272d4b3b638SSrikar Dronamraju * instruction slot. 1273d4b3b638SSrikar Dronamraju */ 1274d4b3b638SSrikar Dronamraju if (unlikely(!current->utask->xol_vaddr)) 1275d4b3b638SSrikar Dronamraju return 0; 1276d4b3b638SSrikar Dronamraju 1277d4b3b638SSrikar Dronamraju current->utask->vaddr = slot_addr; 1278d4b3b638SSrikar Dronamraju offset = current->utask->xol_vaddr & ~PAGE_MASK; 1279d4b3b638SSrikar Dronamraju vaddr = kmap_atomic(area->page); 1280d4b3b638SSrikar Dronamraju memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); 1281d4b3b638SSrikar Dronamraju kunmap_atomic(vaddr); 1282d4b3b638SSrikar Dronamraju 1283d4b3b638SSrikar Dronamraju return current->utask->xol_vaddr; 1284d4b3b638SSrikar Dronamraju } 1285d4b3b638SSrikar Dronamraju 1286d4b3b638SSrikar Dronamraju /* 1287d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1288d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1289d4b3b638SSrikar Dronamraju * subsequent requests. 1290d4b3b638SSrikar Dronamraju */ 1291d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1292d4b3b638SSrikar Dronamraju { 1293d4b3b638SSrikar Dronamraju struct xol_area *area; 1294d4b3b638SSrikar Dronamraju unsigned long vma_end; 1295d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1296d4b3b638SSrikar Dronamraju 1297d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1298d4b3b638SSrikar Dronamraju return; 1299d4b3b638SSrikar Dronamraju 1300d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1301d4b3b638SSrikar Dronamraju 1302d4b3b638SSrikar Dronamraju if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) 1303d4b3b638SSrikar Dronamraju return; 1304d4b3b638SSrikar Dronamraju 1305d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1306d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1307d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1308d4b3b638SSrikar Dronamraju unsigned long offset; 1309d4b3b638SSrikar Dronamraju int slot_nr; 1310d4b3b638SSrikar Dronamraju 1311d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1312d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1313d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1314d4b3b638SSrikar Dronamraju return; 1315d4b3b638SSrikar Dronamraju 1316d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1317d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 1318d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1319d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1320d4b3b638SSrikar Dronamraju 1321d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1322d4b3b638SSrikar Dronamraju } 1323d4b3b638SSrikar Dronamraju } 1324d4b3b638SSrikar Dronamraju 13250326f5a9SSrikar Dronamraju /** 13260326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 13270326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 13280326f5a9SSrikar Dronamraju * instruction. 13290326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 13300326f5a9SSrikar Dronamraju */ 13310326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 13320326f5a9SSrikar Dronamraju { 13330326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 13340326f5a9SSrikar Dronamraju } 13350326f5a9SSrikar Dronamraju 13360326f5a9SSrikar Dronamraju /* 13370326f5a9SSrikar Dronamraju * Called with no locks held. 13380326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 13390326f5a9SSrikar Dronamraju */ 13400326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 13410326f5a9SSrikar Dronamraju { 13420326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13430326f5a9SSrikar Dronamraju 13440326f5a9SSrikar Dronamraju if (!utask) 13450326f5a9SSrikar Dronamraju return; 13460326f5a9SSrikar Dronamraju 13470326f5a9SSrikar Dronamraju if (utask->active_uprobe) 13480326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 13490326f5a9SSrikar Dronamraju 1350d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 13510326f5a9SSrikar Dronamraju kfree(utask); 13520326f5a9SSrikar Dronamraju t->utask = NULL; 13530326f5a9SSrikar Dronamraju } 13540326f5a9SSrikar Dronamraju 13550326f5a9SSrikar Dronamraju /* 13560326f5a9SSrikar Dronamraju * Called in context of a new clone/fork from copy_process. 13570326f5a9SSrikar Dronamraju */ 13580326f5a9SSrikar Dronamraju void uprobe_copy_process(struct task_struct *t) 13590326f5a9SSrikar Dronamraju { 13600326f5a9SSrikar Dronamraju t->utask = NULL; 13610326f5a9SSrikar Dronamraju } 13620326f5a9SSrikar Dronamraju 13630326f5a9SSrikar Dronamraju /* 13640326f5a9SSrikar Dronamraju * Allocate a uprobe_task object for the task. 13650326f5a9SSrikar Dronamraju * Called when the thread hits a breakpoint for the first time. 13660326f5a9SSrikar Dronamraju * 13670326f5a9SSrikar Dronamraju * Returns: 13680326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 13690326f5a9SSrikar Dronamraju * - NULL otherwise 13700326f5a9SSrikar Dronamraju */ 13710326f5a9SSrikar Dronamraju static struct uprobe_task *add_utask(void) 13720326f5a9SSrikar Dronamraju { 13730326f5a9SSrikar Dronamraju struct uprobe_task *utask; 13740326f5a9SSrikar Dronamraju 13750326f5a9SSrikar Dronamraju utask = kzalloc(sizeof *utask, GFP_KERNEL); 13760326f5a9SSrikar Dronamraju if (unlikely(!utask)) 13770326f5a9SSrikar Dronamraju return NULL; 13780326f5a9SSrikar Dronamraju 13790326f5a9SSrikar Dronamraju current->utask = utask; 13800326f5a9SSrikar Dronamraju return utask; 13810326f5a9SSrikar Dronamraju } 13820326f5a9SSrikar Dronamraju 13830326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 13840326f5a9SSrikar Dronamraju static int 13850326f5a9SSrikar Dronamraju pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long vaddr) 13860326f5a9SSrikar Dronamraju { 1387d4b3b638SSrikar Dronamraju if (xol_get_insn_slot(uprobe, vaddr) && !arch_uprobe_pre_xol(&uprobe->arch, regs)) 1388d4b3b638SSrikar Dronamraju return 0; 1389d4b3b638SSrikar Dronamraju 13900326f5a9SSrikar Dronamraju return -EFAULT; 13910326f5a9SSrikar Dronamraju } 13920326f5a9SSrikar Dronamraju 13930326f5a9SSrikar Dronamraju /* 13940326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 13950326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 13960326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 13970326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 13980326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 13990326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 14000326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 14010326f5a9SSrikar Dronamraju */ 14020326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 14030326f5a9SSrikar Dronamraju { 14040326f5a9SSrikar Dronamraju struct task_struct *t = current; 14050326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 14060326f5a9SSrikar Dronamraju 14070326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 14080326f5a9SSrikar Dronamraju return false; 14090326f5a9SSrikar Dronamraju 14100326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 14110326f5a9SSrikar Dronamraju 14120326f5a9SSrikar Dronamraju if (signal_pending(t)) { 14130326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 14140326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 14150326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 14160326f5a9SSrikar Dronamraju 14170326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 14180326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 14190326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 14200326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); 14210326f5a9SSrikar Dronamraju } 14220326f5a9SSrikar Dronamraju } 14230326f5a9SSrikar Dronamraju 14240326f5a9SSrikar Dronamraju return true; 14250326f5a9SSrikar Dronamraju } 14260326f5a9SSrikar Dronamraju 14270326f5a9SSrikar Dronamraju /* 14280326f5a9SSrikar Dronamraju * Avoid singlestepping the original instruction if the original instruction 14290326f5a9SSrikar Dronamraju * is a NOP or can be emulated. 14300326f5a9SSrikar Dronamraju */ 14310326f5a9SSrikar Dronamraju static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) 14320326f5a9SSrikar Dronamraju { 14330326f5a9SSrikar Dronamraju if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 14340326f5a9SSrikar Dronamraju return true; 14350326f5a9SSrikar Dronamraju 14360326f5a9SSrikar Dronamraju uprobe->flags &= ~UPROBE_SKIP_SSTEP; 14370326f5a9SSrikar Dronamraju return false; 14380326f5a9SSrikar Dronamraju } 14390326f5a9SSrikar Dronamraju 1440d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 14410326f5a9SSrikar Dronamraju { 14423a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 14433a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 14440326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 14450326f5a9SSrikar Dronamraju 14460326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 14470326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 14483a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 14493a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 1450cb113b47SOleg Nesterov struct inode *inode = vma->vm_file->f_mapping->host; 1451cb113b47SOleg Nesterov loff_t offset = vaddr_to_offset(vma, bp_vaddr); 14520326f5a9SSrikar Dronamraju 14530326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 14540326f5a9SSrikar Dronamraju } 1455d790d346SOleg Nesterov 1456d790d346SOleg Nesterov if (!uprobe) 1457d790d346SOleg Nesterov *is_swbp = is_swbp_at_addr(mm, bp_vaddr); 1458d790d346SOleg Nesterov } else { 1459d790d346SOleg Nesterov *is_swbp = -EFAULT; 14603a9ea052SOleg Nesterov } 14610326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 14620326f5a9SSrikar Dronamraju 14633a9ea052SOleg Nesterov return uprobe; 14643a9ea052SOleg Nesterov } 14653a9ea052SOleg Nesterov 14663a9ea052SOleg Nesterov /* 14673a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 14683a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 14693a9ea052SOleg Nesterov */ 14703a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 14713a9ea052SOleg Nesterov { 14723a9ea052SOleg Nesterov struct uprobe_task *utask; 14733a9ea052SOleg Nesterov struct uprobe *uprobe; 14743a9ea052SOleg Nesterov unsigned long bp_vaddr; 147556bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 14763a9ea052SOleg Nesterov 14773a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 1478d790d346SOleg Nesterov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 14793a9ea052SOleg Nesterov 14800326f5a9SSrikar Dronamraju if (!uprobe) { 148156bb4cf6SOleg Nesterov if (is_swbp > 0) { 14820326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 14830326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 148456bb4cf6SOleg Nesterov } else { 148556bb4cf6SOleg Nesterov /* 148656bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 148756bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 148856bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 148956bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 149056bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 149156bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 149256bb4cf6SOleg Nesterov */ 149356bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 149456bb4cf6SOleg Nesterov } 14950326f5a9SSrikar Dronamraju return; 14960326f5a9SSrikar Dronamraju } 14970326f5a9SSrikar Dronamraju 14980326f5a9SSrikar Dronamraju utask = current->utask; 14990326f5a9SSrikar Dronamraju if (!utask) { 15000326f5a9SSrikar Dronamraju utask = add_utask(); 15010326f5a9SSrikar Dronamraju /* Cannot allocate; re-execute the instruction. */ 15020326f5a9SSrikar Dronamraju if (!utask) 15030326f5a9SSrikar Dronamraju goto cleanup_ret; 15040326f5a9SSrikar Dronamraju } 15050326f5a9SSrikar Dronamraju utask->active_uprobe = uprobe; 15060326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 15070326f5a9SSrikar Dronamraju if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs)) 15080326f5a9SSrikar Dronamraju goto cleanup_ret; 15090326f5a9SSrikar Dronamraju 15100326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP; 15110326f5a9SSrikar Dronamraju if (!pre_ssout(uprobe, regs, bp_vaddr)) { 15120326f5a9SSrikar Dronamraju user_enable_single_step(current); 15130326f5a9SSrikar Dronamraju return; 15140326f5a9SSrikar Dronamraju } 15150326f5a9SSrikar Dronamraju 15160326f5a9SSrikar Dronamraju cleanup_ret: 15170326f5a9SSrikar Dronamraju if (utask) { 15180326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15190326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 15200326f5a9SSrikar Dronamraju } 15210326f5a9SSrikar Dronamraju if (uprobe) { 15220326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_SKIP_SSTEP)) 15230326f5a9SSrikar Dronamraju 15240326f5a9SSrikar Dronamraju /* 15250326f5a9SSrikar Dronamraju * cannot singlestep; cannot skip instruction; 15260326f5a9SSrikar Dronamraju * re-execute the instruction. 15270326f5a9SSrikar Dronamraju */ 15280326f5a9SSrikar Dronamraju instruction_pointer_set(regs, bp_vaddr); 15290326f5a9SSrikar Dronamraju 15300326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15310326f5a9SSrikar Dronamraju } 15320326f5a9SSrikar Dronamraju } 15330326f5a9SSrikar Dronamraju 15340326f5a9SSrikar Dronamraju /* 15350326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 15360326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 15370326f5a9SSrikar Dronamraju */ 15380326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 15390326f5a9SSrikar Dronamraju { 15400326f5a9SSrikar Dronamraju struct uprobe *uprobe; 15410326f5a9SSrikar Dronamraju 15420326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 15430326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 15440326f5a9SSrikar Dronamraju arch_uprobe_post_xol(&uprobe->arch, regs); 15450326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 15460326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 15470326f5a9SSrikar Dronamraju else 15480326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 15490326f5a9SSrikar Dronamraju 15500326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15510326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15520326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 15530326f5a9SSrikar Dronamraju user_disable_single_step(current); 1554d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 15550326f5a9SSrikar Dronamraju 15560326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 15570326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 15580326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 15590326f5a9SSrikar Dronamraju } 15600326f5a9SSrikar Dronamraju 15610326f5a9SSrikar Dronamraju /* 15620326f5a9SSrikar Dronamraju * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag. (and on 15630326f5a9SSrikar Dronamraju * subsequent probe hits on the thread sets the state to UTASK_BP_HIT) and 15640326f5a9SSrikar Dronamraju * allows the thread to return from interrupt. 15650326f5a9SSrikar Dronamraju * 15660326f5a9SSrikar Dronamraju * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag and 15670326f5a9SSrikar Dronamraju * also sets the state to UTASK_SSTEP_ACK and allows the thread to return from 15680326f5a9SSrikar Dronamraju * interrupt. 15690326f5a9SSrikar Dronamraju * 15700326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 15710326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 15720326f5a9SSrikar Dronamraju */ 15730326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 15740326f5a9SSrikar Dronamraju { 15750326f5a9SSrikar Dronamraju struct uprobe_task *utask; 15760326f5a9SSrikar Dronamraju 15770326f5a9SSrikar Dronamraju utask = current->utask; 15780326f5a9SSrikar Dronamraju if (!utask || utask->state == UTASK_BP_HIT) 15790326f5a9SSrikar Dronamraju handle_swbp(regs); 15800326f5a9SSrikar Dronamraju else 15810326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 15820326f5a9SSrikar Dronamraju } 15830326f5a9SSrikar Dronamraju 15840326f5a9SSrikar Dronamraju /* 15850326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 15860326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 15870326f5a9SSrikar Dronamraju */ 15880326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 15890326f5a9SSrikar Dronamraju { 15900326f5a9SSrikar Dronamraju struct uprobe_task *utask; 15910326f5a9SSrikar Dronamraju 1592682968e0SSrikar Dronamraju if (!current->mm || !atomic_read(¤t->mm->uprobes_state.count)) 1593682968e0SSrikar Dronamraju /* task is currently not uprobed */ 15940326f5a9SSrikar Dronamraju return 0; 15950326f5a9SSrikar Dronamraju 15960326f5a9SSrikar Dronamraju utask = current->utask; 15970326f5a9SSrikar Dronamraju if (utask) 15980326f5a9SSrikar Dronamraju utask->state = UTASK_BP_HIT; 15990326f5a9SSrikar Dronamraju 16000326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 16010326f5a9SSrikar Dronamraju 16020326f5a9SSrikar Dronamraju return 1; 16030326f5a9SSrikar Dronamraju } 16040326f5a9SSrikar Dronamraju 16050326f5a9SSrikar Dronamraju /* 16060326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 16070326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 16080326f5a9SSrikar Dronamraju */ 16090326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 16100326f5a9SSrikar Dronamraju { 16110326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 16120326f5a9SSrikar Dronamraju 16130326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 16140326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 16150326f5a9SSrikar Dronamraju return 0; 16160326f5a9SSrikar Dronamraju 16170326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 16180326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 16190326f5a9SSrikar Dronamraju return 1; 16200326f5a9SSrikar Dronamraju } 16210326f5a9SSrikar Dronamraju 16220326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 16230326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 16240326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 16250326f5a9SSrikar Dronamraju }; 16260326f5a9SSrikar Dronamraju 1627a5f4374aSIngo Molnar static int __init init_uprobes(void) 1628a5f4374aSIngo Molnar { 1629a5f4374aSIngo Molnar int i; 1630a5f4374aSIngo Molnar 1631a5f4374aSIngo Molnar for (i = 0; i < UPROBES_HASH_SZ; i++) { 1632a5f4374aSIngo Molnar mutex_init(&uprobes_mutex[i]); 1633a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 1634a5f4374aSIngo Molnar } 16350326f5a9SSrikar Dronamraju 16360326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 1637a5f4374aSIngo Molnar } 16380326f5a9SSrikar Dronamraju module_init(init_uprobes); 1639a5f4374aSIngo Molnar 1640a5f4374aSIngo Molnar static void __exit exit_uprobes(void) 1641a5f4374aSIngo Molnar { 1642a5f4374aSIngo Molnar } 1643a5f4374aSIngo Molnar module_exit(exit_uprobes); 1644