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 */ 35a5f4374aSIngo Molnar 36a5f4374aSIngo Molnar #include <linux/uprobes.h> 37a5f4374aSIngo Molnar 38d4b3b638SSrikar Dronamraju #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) 39d4b3b638SSrikar Dronamraju #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE 40d4b3b638SSrikar Dronamraju 41a5f4374aSIngo Molnar static struct rb_root uprobes_tree = RB_ROOT; 42a5f4374aSIngo Molnar 43a5f4374aSIngo Molnar static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ 44a5f4374aSIngo Molnar 45a5f4374aSIngo Molnar #define UPROBES_HASH_SZ 13 46a5f4374aSIngo Molnar 47a5f4374aSIngo Molnar /* serialize (un)register */ 48a5f4374aSIngo Molnar static struct mutex uprobes_mutex[UPROBES_HASH_SZ]; 49a5f4374aSIngo Molnar 50a5f4374aSIngo Molnar #define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 51a5f4374aSIngo Molnar 52a5f4374aSIngo Molnar /* serialize uprobe->pending_list */ 53a5f4374aSIngo Molnar static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; 54a5f4374aSIngo Molnar #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 55a5f4374aSIngo Molnar 56a5f4374aSIngo Molnar /* 57a5f4374aSIngo Molnar * uprobe_events allows us to skip the uprobe_mmap if there are no uprobe 58a5f4374aSIngo Molnar * events active at this time. Probably a fine grained per inode count is 59a5f4374aSIngo Molnar * better? 60a5f4374aSIngo Molnar */ 61a5f4374aSIngo Molnar static atomic_t uprobe_events = ATOMIC_INIT(0); 62a5f4374aSIngo Molnar 63a5f4374aSIngo Molnar /* 64a5f4374aSIngo Molnar * Maintain a temporary per vma info that can be used to search if a vma 65a5f4374aSIngo Molnar * has already been handled. This structure is introduced since extending 66a5f4374aSIngo Molnar * vm_area_struct wasnt recommended. 67a5f4374aSIngo Molnar */ 68a5f4374aSIngo Molnar struct vma_info { 69a5f4374aSIngo Molnar struct list_head probe_list; 70a5f4374aSIngo Molnar struct mm_struct *mm; 71a5f4374aSIngo Molnar loff_t vaddr; 72a5f4374aSIngo Molnar }; 73a5f4374aSIngo Molnar 743ff54efdSSrikar Dronamraju struct uprobe { 753ff54efdSSrikar Dronamraju struct rb_node rb_node; /* node in the rb tree */ 763ff54efdSSrikar Dronamraju atomic_t ref; 773ff54efdSSrikar Dronamraju struct rw_semaphore consumer_rwsem; 783ff54efdSSrikar Dronamraju struct list_head pending_list; 793ff54efdSSrikar Dronamraju struct uprobe_consumer *consumers; 803ff54efdSSrikar Dronamraju struct inode *inode; /* Also hold a ref to inode */ 813ff54efdSSrikar Dronamraju loff_t offset; 823ff54efdSSrikar Dronamraju int flags; 833ff54efdSSrikar Dronamraju struct arch_uprobe arch; 843ff54efdSSrikar Dronamraju }; 853ff54efdSSrikar Dronamraju 86a5f4374aSIngo Molnar /* 87a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 88a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 89a5f4374aSIngo Molnar * changed after breakpoint was inserted. 90a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 91a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 92a5f4374aSIngo Molnar * executable vma. 93a5f4374aSIngo Molnar */ 94a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 95a5f4374aSIngo Molnar { 96a5f4374aSIngo Molnar if (!vma->vm_file) 97a5f4374aSIngo Molnar return false; 98a5f4374aSIngo Molnar 99a5f4374aSIngo Molnar if (!is_register) 100a5f4374aSIngo Molnar return true; 101a5f4374aSIngo Molnar 102ea131377SOleg Nesterov if ((vma->vm_flags & (VM_HUGETLB|VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) 103ea131377SOleg Nesterov == (VM_READ|VM_EXEC)) 104a5f4374aSIngo Molnar return true; 105a5f4374aSIngo Molnar 106a5f4374aSIngo Molnar return false; 107a5f4374aSIngo Molnar } 108a5f4374aSIngo Molnar 109a5f4374aSIngo Molnar static loff_t vma_address(struct vm_area_struct *vma, loff_t offset) 110a5f4374aSIngo Molnar { 111a5f4374aSIngo Molnar loff_t vaddr; 112a5f4374aSIngo Molnar 113a5f4374aSIngo Molnar vaddr = vma->vm_start + offset; 114a5f4374aSIngo Molnar vaddr -= vma->vm_pgoff << PAGE_SHIFT; 115a5f4374aSIngo Molnar 116a5f4374aSIngo Molnar return vaddr; 117a5f4374aSIngo Molnar } 118a5f4374aSIngo Molnar 119a5f4374aSIngo Molnar /** 120a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 121a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 122a5f4374aSIngo Molnar * 123a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 124a5f4374aSIngo Molnar * @page: the cowed page we are replacing by kpage 125a5f4374aSIngo Molnar * @kpage: the modified page we replace page by 126a5f4374aSIngo Molnar * 127a5f4374aSIngo Molnar * Returns 0 on success, -EFAULT on failure. 128a5f4374aSIngo Molnar */ 129a5f4374aSIngo Molnar static int __replace_page(struct vm_area_struct *vma, struct page *page, struct page *kpage) 130a5f4374aSIngo Molnar { 131a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 132a5f4374aSIngo Molnar unsigned long addr; 1335323ce71SOleg Nesterov spinlock_t *ptl; 1345323ce71SOleg Nesterov pte_t *ptep; 135a5f4374aSIngo Molnar 136a5f4374aSIngo Molnar addr = page_address_in_vma(page, vma); 137a5f4374aSIngo Molnar if (addr == -EFAULT) 1385323ce71SOleg Nesterov return -EFAULT; 139a5f4374aSIngo Molnar 1405323ce71SOleg Nesterov ptep = page_check_address(page, mm, addr, &ptl, 0); 141a5f4374aSIngo Molnar if (!ptep) 1425323ce71SOleg Nesterov return -EAGAIN; 143a5f4374aSIngo Molnar 144a5f4374aSIngo Molnar get_page(kpage); 145a5f4374aSIngo Molnar page_add_new_anon_rmap(kpage, vma, addr); 146a5f4374aSIngo Molnar 1477396fa81SSrikar Dronamraju if (!PageAnon(page)) { 1487396fa81SSrikar Dronamraju dec_mm_counter(mm, MM_FILEPAGES); 1497396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1507396fa81SSrikar Dronamraju } 1517396fa81SSrikar Dronamraju 152a5f4374aSIngo Molnar flush_cache_page(vma, addr, pte_pfn(*ptep)); 153a5f4374aSIngo Molnar ptep_clear_flush(vma, addr, ptep); 154a5f4374aSIngo Molnar set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); 155a5f4374aSIngo Molnar 156a5f4374aSIngo Molnar page_remove_rmap(page); 157a5f4374aSIngo Molnar if (!page_mapped(page)) 158a5f4374aSIngo Molnar try_to_free_swap(page); 159a5f4374aSIngo Molnar put_page(page); 160a5f4374aSIngo Molnar pte_unmap_unlock(ptep, ptl); 161a5f4374aSIngo Molnar 1625323ce71SOleg Nesterov return 0; 163a5f4374aSIngo Molnar } 164a5f4374aSIngo Molnar 165a5f4374aSIngo Molnar /** 1665cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 167a5f4374aSIngo Molnar * @insn: instruction to be checked. 1685cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 169a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 170a5f4374aSIngo Molnar */ 1715cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 172a5f4374aSIngo Molnar { 1735cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 174a5f4374aSIngo Molnar } 175a5f4374aSIngo Molnar 176a5f4374aSIngo Molnar /* 177a5f4374aSIngo Molnar * NOTE: 178a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 179a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 180a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 181a5f4374aSIngo Molnar * supported by that architecture then we need to modify read_opcode / 182a5f4374aSIngo Molnar * write_opcode accordingly. This would never be a problem for archs that 183a5f4374aSIngo Molnar * have fixed length instructions. 184a5f4374aSIngo Molnar */ 185a5f4374aSIngo Molnar 186a5f4374aSIngo Molnar /* 187a5f4374aSIngo Molnar * write_opcode - write the opcode at a given virtual address. 188e3343e6aSSrikar Dronamraju * @auprobe: arch breakpointing information. 189a5f4374aSIngo Molnar * @mm: the probed process address space. 190a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 191a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 192a5f4374aSIngo Molnar * 193a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 194a5f4374aSIngo Molnar * mm). 195a5f4374aSIngo Molnar * 196a5f4374aSIngo Molnar * For mm @mm, write the opcode at @vaddr. 197a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 198a5f4374aSIngo Molnar */ 199e3343e6aSSrikar Dronamraju static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, 200a5f4374aSIngo Molnar unsigned long vaddr, uprobe_opcode_t opcode) 201a5f4374aSIngo Molnar { 202a5f4374aSIngo Molnar struct page *old_page, *new_page; 203a5f4374aSIngo Molnar struct address_space *mapping; 204a5f4374aSIngo Molnar void *vaddr_old, *vaddr_new; 205a5f4374aSIngo Molnar struct vm_area_struct *vma; 2063ff54efdSSrikar Dronamraju struct uprobe *uprobe; 2075323ce71SOleg Nesterov unsigned long pgoff; 208a5f4374aSIngo Molnar loff_t addr; 209a5f4374aSIngo Molnar int ret; 2105323ce71SOleg Nesterov retry: 211a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 212a5f4374aSIngo Molnar ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); 213a5f4374aSIngo Molnar if (ret <= 0) 214a5f4374aSIngo Molnar return ret; 215a5f4374aSIngo Molnar 216a5f4374aSIngo Molnar ret = -EINVAL; 217a5f4374aSIngo Molnar 218a5f4374aSIngo Molnar /* 219a5f4374aSIngo Molnar * We are interested in text pages only. Our pages of interest 220a5f4374aSIngo Molnar * should be mapped for read and execute only. We desist from 221a5f4374aSIngo Molnar * adding probes in write mapped pages since the breakpoints 222a5f4374aSIngo Molnar * might end up in the file copy. 223a5f4374aSIngo Molnar */ 2245cb4ac3aSSrikar Dronamraju if (!valid_vma(vma, is_swbp_insn(&opcode))) 225a5f4374aSIngo Molnar goto put_out; 226a5f4374aSIngo Molnar 2273ff54efdSSrikar Dronamraju uprobe = container_of(auprobe, struct uprobe, arch); 228a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 229a5f4374aSIngo Molnar if (mapping != vma->vm_file->f_mapping) 230a5f4374aSIngo Molnar goto put_out; 231a5f4374aSIngo Molnar 232a5f4374aSIngo Molnar addr = vma_address(vma, uprobe->offset); 233a5f4374aSIngo Molnar if (vaddr != (unsigned long)addr) 234a5f4374aSIngo Molnar goto put_out; 235a5f4374aSIngo Molnar 236a5f4374aSIngo Molnar ret = -ENOMEM; 237a5f4374aSIngo Molnar new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); 238a5f4374aSIngo Molnar if (!new_page) 239a5f4374aSIngo Molnar goto put_out; 240a5f4374aSIngo Molnar 241a5f4374aSIngo Molnar __SetPageUptodate(new_page); 242a5f4374aSIngo Molnar 243a5f4374aSIngo Molnar /* 244a5f4374aSIngo Molnar * lock page will serialize against do_wp_page()'s 245a5f4374aSIngo Molnar * PageAnon() handling 246a5f4374aSIngo Molnar */ 247a5f4374aSIngo Molnar lock_page(old_page); 248a5f4374aSIngo Molnar /* copy the page now that we've got it stable */ 249a5f4374aSIngo Molnar vaddr_old = kmap_atomic(old_page); 250a5f4374aSIngo Molnar vaddr_new = kmap_atomic(new_page); 251a5f4374aSIngo Molnar 252a5f4374aSIngo Molnar memcpy(vaddr_new, vaddr_old, PAGE_SIZE); 253a5f4374aSIngo Molnar 254a5f4374aSIngo Molnar /* poke the new insn in, ASSUMES we don't cross page boundary */ 2555323ce71SOleg Nesterov pgoff = (vaddr & ~PAGE_MASK); 2565323ce71SOleg Nesterov BUG_ON(pgoff + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 2575323ce71SOleg Nesterov memcpy(vaddr_new + pgoff, &opcode, UPROBE_SWBP_INSN_SIZE); 258a5f4374aSIngo Molnar 259a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 260a5f4374aSIngo Molnar kunmap_atomic(vaddr_old); 261a5f4374aSIngo Molnar 262a5f4374aSIngo Molnar ret = anon_vma_prepare(vma); 263a5f4374aSIngo Molnar if (ret) 264a5f4374aSIngo Molnar goto unlock_out; 265a5f4374aSIngo Molnar 266a5f4374aSIngo Molnar lock_page(new_page); 267a5f4374aSIngo Molnar ret = __replace_page(vma, old_page, new_page); 268a5f4374aSIngo Molnar unlock_page(new_page); 269a5f4374aSIngo Molnar 270a5f4374aSIngo Molnar unlock_out: 271a5f4374aSIngo Molnar unlock_page(old_page); 272a5f4374aSIngo Molnar page_cache_release(new_page); 273a5f4374aSIngo Molnar 274a5f4374aSIngo Molnar put_out: 275a5f4374aSIngo Molnar put_page(old_page); 276a5f4374aSIngo Molnar 2775323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 2785323ce71SOleg Nesterov goto retry; 279a5f4374aSIngo Molnar return ret; 280a5f4374aSIngo Molnar } 281a5f4374aSIngo Molnar 282a5f4374aSIngo Molnar /** 283a5f4374aSIngo Molnar * read_opcode - read the opcode at a given virtual address. 284a5f4374aSIngo Molnar * @mm: the probed process address space. 285a5f4374aSIngo Molnar * @vaddr: the virtual address to read the opcode. 286a5f4374aSIngo Molnar * @opcode: location to store the read opcode. 287a5f4374aSIngo Molnar * 288a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 289a5f4374aSIngo Molnar * mm. 290a5f4374aSIngo Molnar * 291a5f4374aSIngo Molnar * For mm @mm, read the opcode at @vaddr and store it in @opcode. 292a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 293a5f4374aSIngo Molnar */ 294a5f4374aSIngo Molnar static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode) 295a5f4374aSIngo Molnar { 296a5f4374aSIngo Molnar struct page *page; 297a5f4374aSIngo Molnar void *vaddr_new; 298a5f4374aSIngo Molnar int ret; 299a5f4374aSIngo Molnar 300a3d7bb47SOleg Nesterov ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); 301a5f4374aSIngo Molnar if (ret <= 0) 302a5f4374aSIngo Molnar return ret; 303a5f4374aSIngo Molnar 304a5f4374aSIngo Molnar lock_page(page); 305a5f4374aSIngo Molnar vaddr_new = kmap_atomic(page); 306a5f4374aSIngo Molnar vaddr &= ~PAGE_MASK; 3075cb4ac3aSSrikar Dronamraju memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE); 308a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 309a5f4374aSIngo Molnar unlock_page(page); 310a5f4374aSIngo Molnar 311a5f4374aSIngo Molnar put_page(page); 312a5f4374aSIngo Molnar 313a5f4374aSIngo Molnar return 0; 314a5f4374aSIngo Molnar } 315a5f4374aSIngo Molnar 3165cb4ac3aSSrikar Dronamraju static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) 317a5f4374aSIngo Molnar { 318a5f4374aSIngo Molnar uprobe_opcode_t opcode; 319a5f4374aSIngo Molnar int result; 320a5f4374aSIngo Molnar 321c00b2750SOleg Nesterov if (current->mm == mm) { 322c00b2750SOleg Nesterov pagefault_disable(); 323c00b2750SOleg Nesterov result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, 324c00b2750SOleg Nesterov sizeof(opcode)); 325c00b2750SOleg Nesterov pagefault_enable(); 326c00b2750SOleg Nesterov 327c00b2750SOleg Nesterov if (likely(result == 0)) 328c00b2750SOleg Nesterov goto out; 329c00b2750SOleg Nesterov } 330c00b2750SOleg Nesterov 331a5f4374aSIngo Molnar result = read_opcode(mm, vaddr, &opcode); 332a5f4374aSIngo Molnar if (result) 333a5f4374aSIngo Molnar return result; 334c00b2750SOleg Nesterov out: 3355cb4ac3aSSrikar Dronamraju if (is_swbp_insn(&opcode)) 336a5f4374aSIngo Molnar return 1; 337a5f4374aSIngo Molnar 338a5f4374aSIngo Molnar return 0; 339a5f4374aSIngo Molnar } 340a5f4374aSIngo Molnar 341a5f4374aSIngo Molnar /** 3425cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 343e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 344a5f4374aSIngo Molnar * @mm: the probed process address space. 345a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 346a5f4374aSIngo Molnar * 347a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 348a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 349a5f4374aSIngo Molnar */ 3505cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 351a5f4374aSIngo Molnar { 352a5f4374aSIngo Molnar int result; 353a5f4374aSIngo Molnar 3545cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 355a5f4374aSIngo Molnar if (result == 1) 356a5f4374aSIngo Molnar return -EEXIST; 357a5f4374aSIngo Molnar 358a5f4374aSIngo Molnar if (result) 359a5f4374aSIngo Molnar return result; 360a5f4374aSIngo Molnar 3615cb4ac3aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); 362a5f4374aSIngo Molnar } 363a5f4374aSIngo Molnar 364a5f4374aSIngo Molnar /** 365a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 366a5f4374aSIngo Molnar * @mm: the probed process address space. 367e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 368a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 369a5f4374aSIngo Molnar * @verify: if true, verify existance of breakpoint instruction. 370a5f4374aSIngo Molnar * 371a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 372a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 373a5f4374aSIngo Molnar */ 374a5f4374aSIngo Molnar int __weak 375e3343e6aSSrikar Dronamraju set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, bool verify) 376a5f4374aSIngo Molnar { 377a5f4374aSIngo Molnar if (verify) { 378a5f4374aSIngo Molnar int result; 379a5f4374aSIngo Molnar 3805cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 381a5f4374aSIngo Molnar if (!result) 382a5f4374aSIngo Molnar return -EINVAL; 383a5f4374aSIngo Molnar 384a5f4374aSIngo Molnar if (result != 1) 385a5f4374aSIngo Molnar return result; 386a5f4374aSIngo Molnar } 387e3343e6aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); 388a5f4374aSIngo Molnar } 389a5f4374aSIngo Molnar 390a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 391a5f4374aSIngo Molnar { 392a5f4374aSIngo Molnar if (l->inode < r->inode) 393a5f4374aSIngo Molnar return -1; 394a5f4374aSIngo Molnar 395a5f4374aSIngo Molnar if (l->inode > r->inode) 396a5f4374aSIngo Molnar return 1; 397a5f4374aSIngo Molnar 398a5f4374aSIngo Molnar if (l->offset < r->offset) 399a5f4374aSIngo Molnar return -1; 400a5f4374aSIngo Molnar 401a5f4374aSIngo Molnar if (l->offset > r->offset) 402a5f4374aSIngo Molnar return 1; 403a5f4374aSIngo Molnar 404a5f4374aSIngo Molnar return 0; 405a5f4374aSIngo Molnar } 406a5f4374aSIngo Molnar 407a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 408a5f4374aSIngo Molnar { 409a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 410a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 411a5f4374aSIngo Molnar struct uprobe *uprobe; 412a5f4374aSIngo Molnar int match; 413a5f4374aSIngo Molnar 414a5f4374aSIngo Molnar while (n) { 415a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 416a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 417a5f4374aSIngo Molnar if (!match) { 418a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 419a5f4374aSIngo Molnar return uprobe; 420a5f4374aSIngo Molnar } 421a5f4374aSIngo Molnar 422a5f4374aSIngo Molnar if (match < 0) 423a5f4374aSIngo Molnar n = n->rb_left; 424a5f4374aSIngo Molnar else 425a5f4374aSIngo Molnar n = n->rb_right; 426a5f4374aSIngo Molnar } 427a5f4374aSIngo Molnar return NULL; 428a5f4374aSIngo Molnar } 429a5f4374aSIngo Molnar 430a5f4374aSIngo Molnar /* 431a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 432a5f4374aSIngo Molnar * Acquires uprobes_treelock 433a5f4374aSIngo Molnar */ 434a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 435a5f4374aSIngo Molnar { 436a5f4374aSIngo Molnar struct uprobe *uprobe; 437a5f4374aSIngo Molnar unsigned long flags; 438a5f4374aSIngo Molnar 439a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 440a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 441a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 442a5f4374aSIngo Molnar 443a5f4374aSIngo Molnar return uprobe; 444a5f4374aSIngo Molnar } 445a5f4374aSIngo Molnar 446a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 447a5f4374aSIngo Molnar { 448a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 449a5f4374aSIngo Molnar struct rb_node *parent = NULL; 450a5f4374aSIngo Molnar struct uprobe *u; 451a5f4374aSIngo Molnar int match; 452a5f4374aSIngo Molnar 453a5f4374aSIngo Molnar while (*p) { 454a5f4374aSIngo Molnar parent = *p; 455a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 456a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 457a5f4374aSIngo Molnar if (!match) { 458a5f4374aSIngo Molnar atomic_inc(&u->ref); 459a5f4374aSIngo Molnar return u; 460a5f4374aSIngo Molnar } 461a5f4374aSIngo Molnar 462a5f4374aSIngo Molnar if (match < 0) 463a5f4374aSIngo Molnar p = &parent->rb_left; 464a5f4374aSIngo Molnar else 465a5f4374aSIngo Molnar p = &parent->rb_right; 466a5f4374aSIngo Molnar 467a5f4374aSIngo Molnar } 468a5f4374aSIngo Molnar 469a5f4374aSIngo Molnar u = NULL; 470a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 471a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 472a5f4374aSIngo Molnar /* get access + creation ref */ 473a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 474a5f4374aSIngo Molnar 475a5f4374aSIngo Molnar return u; 476a5f4374aSIngo Molnar } 477a5f4374aSIngo Molnar 478a5f4374aSIngo Molnar /* 479a5f4374aSIngo Molnar * Acquire uprobes_treelock. 480a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 481a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 482a5f4374aSIngo Molnar * 483a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 484a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 485a5f4374aSIngo Molnar */ 486a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 487a5f4374aSIngo Molnar { 488a5f4374aSIngo Molnar unsigned long flags; 489a5f4374aSIngo Molnar struct uprobe *u; 490a5f4374aSIngo Molnar 491a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 492a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 493a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 494a5f4374aSIngo Molnar 4950326f5a9SSrikar Dronamraju /* For now assume that the instruction need not be single-stepped */ 4960326f5a9SSrikar Dronamraju uprobe->flags |= UPROBE_SKIP_SSTEP; 4970326f5a9SSrikar Dronamraju 498a5f4374aSIngo Molnar return u; 499a5f4374aSIngo Molnar } 500a5f4374aSIngo Molnar 501a5f4374aSIngo Molnar static void put_uprobe(struct uprobe *uprobe) 502a5f4374aSIngo Molnar { 503a5f4374aSIngo Molnar if (atomic_dec_and_test(&uprobe->ref)) 504a5f4374aSIngo Molnar kfree(uprobe); 505a5f4374aSIngo Molnar } 506a5f4374aSIngo Molnar 507a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 508a5f4374aSIngo Molnar { 509a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 510a5f4374aSIngo Molnar 511a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 512a5f4374aSIngo Molnar if (!uprobe) 513a5f4374aSIngo Molnar return NULL; 514a5f4374aSIngo Molnar 515a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 516a5f4374aSIngo Molnar uprobe->offset = offset; 517a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 518a5f4374aSIngo Molnar INIT_LIST_HEAD(&uprobe->pending_list); 519a5f4374aSIngo Molnar 520a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 521a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 522a5f4374aSIngo Molnar 523a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 524a5f4374aSIngo Molnar if (cur_uprobe) { 525a5f4374aSIngo Molnar kfree(uprobe); 526a5f4374aSIngo Molnar uprobe = cur_uprobe; 527a5f4374aSIngo Molnar iput(inode); 528a5f4374aSIngo Molnar } else { 529a5f4374aSIngo Molnar atomic_inc(&uprobe_events); 530a5f4374aSIngo Molnar } 531a5f4374aSIngo Molnar 532a5f4374aSIngo Molnar return uprobe; 533a5f4374aSIngo Molnar } 534a5f4374aSIngo Molnar 5350326f5a9SSrikar Dronamraju static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 5360326f5a9SSrikar Dronamraju { 5370326f5a9SSrikar Dronamraju struct uprobe_consumer *uc; 5380326f5a9SSrikar Dronamraju 5390326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_RUN_HANDLER)) 5400326f5a9SSrikar Dronamraju return; 5410326f5a9SSrikar Dronamraju 5420326f5a9SSrikar Dronamraju down_read(&uprobe->consumer_rwsem); 5430326f5a9SSrikar Dronamraju for (uc = uprobe->consumers; uc; uc = uc->next) { 5440326f5a9SSrikar Dronamraju if (!uc->filter || uc->filter(uc, current)) 5450326f5a9SSrikar Dronamraju uc->handler(uc, regs); 5460326f5a9SSrikar Dronamraju } 5470326f5a9SSrikar Dronamraju up_read(&uprobe->consumer_rwsem); 5480326f5a9SSrikar Dronamraju } 5490326f5a9SSrikar Dronamraju 550a5f4374aSIngo Molnar /* Returns the previous consumer */ 551a5f4374aSIngo Molnar static struct uprobe_consumer * 552e3343e6aSSrikar Dronamraju consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 553a5f4374aSIngo Molnar { 554a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 555e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 556e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 557a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 558a5f4374aSIngo Molnar 559e3343e6aSSrikar Dronamraju return uc->next; 560a5f4374aSIngo Molnar } 561a5f4374aSIngo Molnar 562a5f4374aSIngo Molnar /* 563e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 564e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 565a5f4374aSIngo Molnar * or return false. 566a5f4374aSIngo Molnar */ 567e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 568a5f4374aSIngo Molnar { 569a5f4374aSIngo Molnar struct uprobe_consumer **con; 570a5f4374aSIngo Molnar bool ret = false; 571a5f4374aSIngo Molnar 572a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 573a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 574e3343e6aSSrikar Dronamraju if (*con == uc) { 575e3343e6aSSrikar Dronamraju *con = uc->next; 576a5f4374aSIngo Molnar ret = true; 577a5f4374aSIngo Molnar break; 578a5f4374aSIngo Molnar } 579a5f4374aSIngo Molnar } 580a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 581a5f4374aSIngo Molnar 582a5f4374aSIngo Molnar return ret; 583a5f4374aSIngo Molnar } 584a5f4374aSIngo Molnar 585e3343e6aSSrikar Dronamraju static int 586e3343e6aSSrikar Dronamraju __copy_insn(struct address_space *mapping, struct vm_area_struct *vma, char *insn, 587a5f4374aSIngo Molnar unsigned long nbytes, unsigned long offset) 588a5f4374aSIngo Molnar { 589a5f4374aSIngo Molnar struct file *filp = vma->vm_file; 590a5f4374aSIngo Molnar struct page *page; 591a5f4374aSIngo Molnar void *vaddr; 592a5f4374aSIngo Molnar unsigned long off1; 593a5f4374aSIngo Molnar unsigned long idx; 594a5f4374aSIngo Molnar 595a5f4374aSIngo Molnar if (!filp) 596a5f4374aSIngo Molnar return -EINVAL; 597a5f4374aSIngo Molnar 598cc359d18SOleg Nesterov if (!mapping->a_ops->readpage) 599cc359d18SOleg Nesterov return -EIO; 600cc359d18SOleg Nesterov 601a5f4374aSIngo Molnar idx = (unsigned long)(offset >> PAGE_CACHE_SHIFT); 602a5f4374aSIngo Molnar off1 = offset &= ~PAGE_MASK; 603a5f4374aSIngo Molnar 604a5f4374aSIngo Molnar /* 605a5f4374aSIngo Molnar * Ensure that the page that has the original instruction is 606a5f4374aSIngo Molnar * populated and in page-cache. 607a5f4374aSIngo Molnar */ 608a5f4374aSIngo Molnar page = read_mapping_page(mapping, idx, filp); 609a5f4374aSIngo Molnar if (IS_ERR(page)) 610a5f4374aSIngo Molnar return PTR_ERR(page); 611a5f4374aSIngo Molnar 612a5f4374aSIngo Molnar vaddr = kmap_atomic(page); 613a5f4374aSIngo Molnar memcpy(insn, vaddr + off1, nbytes); 614a5f4374aSIngo Molnar kunmap_atomic(vaddr); 615a5f4374aSIngo Molnar page_cache_release(page); 616a5f4374aSIngo Molnar 617a5f4374aSIngo Molnar return 0; 618a5f4374aSIngo Molnar } 619a5f4374aSIngo Molnar 620e3343e6aSSrikar Dronamraju static int 621e3343e6aSSrikar Dronamraju copy_insn(struct uprobe *uprobe, struct vm_area_struct *vma, unsigned long addr) 622a5f4374aSIngo Molnar { 623a5f4374aSIngo Molnar struct address_space *mapping; 624a5f4374aSIngo Molnar unsigned long nbytes; 625a5f4374aSIngo Molnar int bytes; 626a5f4374aSIngo Molnar 627a5f4374aSIngo Molnar addr &= ~PAGE_MASK; 628a5f4374aSIngo Molnar nbytes = PAGE_SIZE - addr; 629a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 630a5f4374aSIngo Molnar 631a5f4374aSIngo Molnar /* Instruction at end of binary; copy only available bytes */ 632a5f4374aSIngo Molnar if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) 633a5f4374aSIngo Molnar bytes = uprobe->inode->i_size - uprobe->offset; 634a5f4374aSIngo Molnar else 635a5f4374aSIngo Molnar bytes = MAX_UINSN_BYTES; 636a5f4374aSIngo Molnar 637a5f4374aSIngo Molnar /* Instruction at the page-boundary; copy bytes in second page */ 638a5f4374aSIngo Molnar if (nbytes < bytes) { 6393ff54efdSSrikar Dronamraju if (__copy_insn(mapping, vma, uprobe->arch.insn + nbytes, 640a5f4374aSIngo Molnar bytes - nbytes, uprobe->offset + nbytes)) 641a5f4374aSIngo Molnar return -ENOMEM; 642a5f4374aSIngo Molnar 643a5f4374aSIngo Molnar bytes = nbytes; 644a5f4374aSIngo Molnar } 6453ff54efdSSrikar Dronamraju return __copy_insn(mapping, vma, uprobe->arch.insn, bytes, uprobe->offset); 646a5f4374aSIngo Molnar } 647a5f4374aSIngo Molnar 648682968e0SSrikar Dronamraju /* 649682968e0SSrikar Dronamraju * How mm->uprobes_state.count gets updated 650682968e0SSrikar Dronamraju * uprobe_mmap() increments the count if 651682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 652682968e0SSrikar Dronamraju * - it cannot add a breakpoint, but sees that there is a underlying 653682968e0SSrikar Dronamraju * breakpoint (via a is_swbp_at_addr()). 654682968e0SSrikar Dronamraju * 655682968e0SSrikar Dronamraju * uprobe_munmap() decrements the count if 656682968e0SSrikar Dronamraju * - it sees a underlying breakpoint, (via is_swbp_at_addr) 657682968e0SSrikar Dronamraju * (Subsequent uprobe_unregister wouldnt find the breakpoint 658682968e0SSrikar Dronamraju * unless a uprobe_mmap kicks in, since the old vma would be 659682968e0SSrikar Dronamraju * dropped just after uprobe_munmap.) 660682968e0SSrikar Dronamraju * 661682968e0SSrikar Dronamraju * uprobe_register increments the count if: 662682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 663682968e0SSrikar Dronamraju * 664682968e0SSrikar Dronamraju * uprobe_unregister decrements the count if: 665682968e0SSrikar Dronamraju * - it sees a underlying breakpoint and removes successfully. 666682968e0SSrikar Dronamraju * (via is_swbp_at_addr) 667682968e0SSrikar Dronamraju * (Subsequent uprobe_munmap wouldnt find the breakpoint 668682968e0SSrikar Dronamraju * since there is no underlying breakpoint after the 669682968e0SSrikar Dronamraju * breakpoint removal.) 670682968e0SSrikar Dronamraju */ 671e3343e6aSSrikar Dronamraju static int 672e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 673a5f4374aSIngo Molnar struct vm_area_struct *vma, loff_t vaddr) 674a5f4374aSIngo Molnar { 675a5f4374aSIngo Molnar unsigned long addr; 676a5f4374aSIngo Molnar int ret; 677a5f4374aSIngo Molnar 678a5f4374aSIngo Molnar /* 679a5f4374aSIngo Molnar * If probe is being deleted, unregister thread could be done with 680a5f4374aSIngo Molnar * the vma-rmap-walk through. Adding a probe now can be fatal since 681a5f4374aSIngo Molnar * nobody will be able to cleanup. Also we could be from fork or 682a5f4374aSIngo Molnar * mremap path, where the probe might have already been inserted. 683a5f4374aSIngo Molnar * Hence behave as if probe already existed. 684a5f4374aSIngo Molnar */ 685a5f4374aSIngo Molnar if (!uprobe->consumers) 686a5f4374aSIngo Molnar return -EEXIST; 687a5f4374aSIngo Molnar 688a5f4374aSIngo Molnar addr = (unsigned long)vaddr; 689a5f4374aSIngo Molnar 690900771a4SSrikar Dronamraju if (!(uprobe->flags & UPROBE_COPY_INSN)) { 691a5f4374aSIngo Molnar ret = copy_insn(uprobe, vma, addr); 692a5f4374aSIngo Molnar if (ret) 693a5f4374aSIngo Molnar return ret; 694a5f4374aSIngo Molnar 6955cb4ac3aSSrikar Dronamraju if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) 696a5f4374aSIngo Molnar return -EEXIST; 697a5f4374aSIngo Molnar 6987eb9ba5eSAnanth N Mavinakayanahalli ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, addr); 699a5f4374aSIngo Molnar if (ret) 700a5f4374aSIngo Molnar return ret; 701a5f4374aSIngo Molnar 702900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_COPY_INSN; 703a5f4374aSIngo Molnar } 704682968e0SSrikar Dronamraju 705682968e0SSrikar Dronamraju /* 706682968e0SSrikar Dronamraju * Ideally, should be updating the probe count after the breakpoint 707682968e0SSrikar Dronamraju * has been successfully inserted. However a thread could hit the 708682968e0SSrikar Dronamraju * breakpoint we just inserted even before the probe count is 709682968e0SSrikar Dronamraju * incremented. If this is the first breakpoint placed, breakpoint 710682968e0SSrikar Dronamraju * notifier might ignore uprobes and pass the trap to the thread. 711682968e0SSrikar Dronamraju * Hence increment before and decrement on failure. 712682968e0SSrikar Dronamraju */ 713682968e0SSrikar Dronamraju atomic_inc(&mm->uprobes_state.count); 7145cb4ac3aSSrikar Dronamraju ret = set_swbp(&uprobe->arch, mm, addr); 715682968e0SSrikar Dronamraju if (ret) 716682968e0SSrikar Dronamraju atomic_dec(&mm->uprobes_state.count); 717a5f4374aSIngo Molnar 718a5f4374aSIngo Molnar return ret; 719a5f4374aSIngo Molnar } 720a5f4374aSIngo Molnar 721e3343e6aSSrikar Dronamraju static void 722e3343e6aSSrikar Dronamraju remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, loff_t vaddr) 723a5f4374aSIngo Molnar { 724682968e0SSrikar Dronamraju if (!set_orig_insn(&uprobe->arch, mm, (unsigned long)vaddr, true)) 725682968e0SSrikar Dronamraju atomic_dec(&mm->uprobes_state.count); 726a5f4374aSIngo Molnar } 727a5f4374aSIngo Molnar 7280326f5a9SSrikar Dronamraju /* 729778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 730778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 731778b032dSOleg Nesterov * See find_active_uprobe(). 7320326f5a9SSrikar Dronamraju */ 733a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 734a5f4374aSIngo Molnar { 735a5f4374aSIngo Molnar unsigned long flags; 736a5f4374aSIngo Molnar 737a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 738a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 739a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 740a5f4374aSIngo Molnar iput(uprobe->inode); 741a5f4374aSIngo Molnar put_uprobe(uprobe); 742a5f4374aSIngo Molnar atomic_dec(&uprobe_events); 743a5f4374aSIngo Molnar } 744a5f4374aSIngo Molnar 745e3343e6aSSrikar Dronamraju static struct vma_info * 746e3343e6aSSrikar Dronamraju __find_next_vma_info(struct address_space *mapping, struct list_head *head, 747e3343e6aSSrikar Dronamraju struct vma_info *vi, loff_t offset, bool is_register) 748a5f4374aSIngo Molnar { 749a5f4374aSIngo Molnar struct prio_tree_iter iter; 750a5f4374aSIngo Molnar struct vm_area_struct *vma; 751a5f4374aSIngo Molnar struct vma_info *tmpvi; 752a5f4374aSIngo Molnar unsigned long pgoff; 753a5f4374aSIngo Molnar int existing_vma; 754a5f4374aSIngo Molnar loff_t vaddr; 755a5f4374aSIngo Molnar 756a5f4374aSIngo Molnar pgoff = offset >> PAGE_SHIFT; 757a5f4374aSIngo Molnar 758a5f4374aSIngo Molnar vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 759a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 760a5f4374aSIngo Molnar continue; 761a5f4374aSIngo Molnar 762a5f4374aSIngo Molnar existing_vma = 0; 763a5f4374aSIngo Molnar vaddr = vma_address(vma, offset); 764a5f4374aSIngo Molnar 765a5f4374aSIngo Molnar list_for_each_entry(tmpvi, head, probe_list) { 766a5f4374aSIngo Molnar if (tmpvi->mm == vma->vm_mm && tmpvi->vaddr == vaddr) { 767a5f4374aSIngo Molnar existing_vma = 1; 768a5f4374aSIngo Molnar break; 769a5f4374aSIngo Molnar } 770a5f4374aSIngo Molnar } 771a5f4374aSIngo Molnar 772a5f4374aSIngo Molnar /* 773a5f4374aSIngo Molnar * Another vma needs a probe to be installed. However skip 774a5f4374aSIngo Molnar * installing the probe if the vma is about to be unlinked. 775a5f4374aSIngo Molnar */ 776a5f4374aSIngo Molnar if (!existing_vma && atomic_inc_not_zero(&vma->vm_mm->mm_users)) { 777a5f4374aSIngo Molnar vi->mm = vma->vm_mm; 778a5f4374aSIngo Molnar vi->vaddr = vaddr; 779a5f4374aSIngo Molnar list_add(&vi->probe_list, head); 780a5f4374aSIngo Molnar 781a5f4374aSIngo Molnar return vi; 782a5f4374aSIngo Molnar } 783a5f4374aSIngo Molnar } 784a5f4374aSIngo Molnar 785a5f4374aSIngo Molnar return NULL; 786a5f4374aSIngo Molnar } 787a5f4374aSIngo Molnar 788a5f4374aSIngo Molnar /* 789a5f4374aSIngo Molnar * Iterate in the rmap prio tree and find a vma where a probe has not 790a5f4374aSIngo Molnar * yet been inserted. 791a5f4374aSIngo Molnar */ 792a5f4374aSIngo Molnar static struct vma_info * 793e3343e6aSSrikar Dronamraju find_next_vma_info(struct address_space *mapping, struct list_head *head, 794e3343e6aSSrikar Dronamraju loff_t offset, bool is_register) 795a5f4374aSIngo Molnar { 796a5f4374aSIngo Molnar struct vma_info *vi, *retvi; 797a5f4374aSIngo Molnar 798a5f4374aSIngo Molnar vi = kzalloc(sizeof(struct vma_info), GFP_KERNEL); 799a5f4374aSIngo Molnar if (!vi) 800a5f4374aSIngo Molnar return ERR_PTR(-ENOMEM); 801a5f4374aSIngo Molnar 802a5f4374aSIngo Molnar mutex_lock(&mapping->i_mmap_mutex); 803e3343e6aSSrikar Dronamraju retvi = __find_next_vma_info(mapping, head, vi, offset, is_register); 804a5f4374aSIngo Molnar mutex_unlock(&mapping->i_mmap_mutex); 805a5f4374aSIngo Molnar 806a5f4374aSIngo Molnar if (!retvi) 807a5f4374aSIngo Molnar kfree(vi); 808a5f4374aSIngo Molnar 809a5f4374aSIngo Molnar return retvi; 810a5f4374aSIngo Molnar } 811a5f4374aSIngo Molnar 812a5f4374aSIngo Molnar static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 813a5f4374aSIngo Molnar { 814a5f4374aSIngo Molnar struct list_head try_list; 815a5f4374aSIngo Molnar struct vm_area_struct *vma; 816a5f4374aSIngo Molnar struct address_space *mapping; 817a5f4374aSIngo Molnar struct vma_info *vi, *tmpvi; 818a5f4374aSIngo Molnar struct mm_struct *mm; 819a5f4374aSIngo Molnar loff_t vaddr; 820a5f4374aSIngo Molnar int ret; 821a5f4374aSIngo Molnar 822a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 823a5f4374aSIngo Molnar INIT_LIST_HEAD(&try_list); 824a5f4374aSIngo Molnar 825a5f4374aSIngo Molnar ret = 0; 826a5f4374aSIngo Molnar 827a5f4374aSIngo Molnar for (;;) { 828e3343e6aSSrikar Dronamraju vi = find_next_vma_info(mapping, &try_list, uprobe->offset, is_register); 829a5f4374aSIngo Molnar if (!vi) 830a5f4374aSIngo Molnar break; 831a5f4374aSIngo Molnar 832a5f4374aSIngo Molnar if (IS_ERR(vi)) { 833a5f4374aSIngo Molnar ret = PTR_ERR(vi); 834a5f4374aSIngo Molnar break; 835a5f4374aSIngo Molnar } 836a5f4374aSIngo Molnar 837a5f4374aSIngo Molnar mm = vi->mm; 83877fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 839a5f4374aSIngo Molnar vma = find_vma(mm, (unsigned long)vi->vaddr); 840a5f4374aSIngo Molnar if (!vma || !valid_vma(vma, is_register)) { 841a5f4374aSIngo Molnar list_del(&vi->probe_list); 842a5f4374aSIngo Molnar kfree(vi); 84377fc4af1SOleg Nesterov up_write(&mm->mmap_sem); 844a5f4374aSIngo Molnar mmput(mm); 845a5f4374aSIngo Molnar continue; 846a5f4374aSIngo Molnar } 847a5f4374aSIngo Molnar vaddr = vma_address(vma, uprobe->offset); 848a5f4374aSIngo Molnar if (vma->vm_file->f_mapping->host != uprobe->inode || 849a5f4374aSIngo Molnar vaddr != vi->vaddr) { 850a5f4374aSIngo Molnar list_del(&vi->probe_list); 851a5f4374aSIngo Molnar kfree(vi); 85277fc4af1SOleg Nesterov up_write(&mm->mmap_sem); 853a5f4374aSIngo Molnar mmput(mm); 854a5f4374aSIngo Molnar continue; 855a5f4374aSIngo Molnar } 856a5f4374aSIngo Molnar 857a5f4374aSIngo Molnar if (is_register) 858e3343e6aSSrikar Dronamraju ret = install_breakpoint(uprobe, mm, vma, vi->vaddr); 859a5f4374aSIngo Molnar else 860e3343e6aSSrikar Dronamraju remove_breakpoint(uprobe, mm, vi->vaddr); 861a5f4374aSIngo Molnar 86277fc4af1SOleg Nesterov up_write(&mm->mmap_sem); 863a5f4374aSIngo Molnar mmput(mm); 864a5f4374aSIngo Molnar if (is_register) { 865a5f4374aSIngo Molnar if (ret && ret == -EEXIST) 866a5f4374aSIngo Molnar ret = 0; 867a5f4374aSIngo Molnar if (ret) 868a5f4374aSIngo Molnar break; 869a5f4374aSIngo Molnar } 870a5f4374aSIngo Molnar } 871a5f4374aSIngo Molnar 872a5f4374aSIngo Molnar list_for_each_entry_safe(vi, tmpvi, &try_list, probe_list) { 873a5f4374aSIngo Molnar list_del(&vi->probe_list); 874a5f4374aSIngo Molnar kfree(vi); 875a5f4374aSIngo Molnar } 876a5f4374aSIngo Molnar 877a5f4374aSIngo Molnar return ret; 878a5f4374aSIngo Molnar } 879a5f4374aSIngo Molnar 880a5f4374aSIngo Molnar static int __uprobe_register(struct uprobe *uprobe) 881a5f4374aSIngo Molnar { 882a5f4374aSIngo Molnar return register_for_each_vma(uprobe, true); 883a5f4374aSIngo Molnar } 884a5f4374aSIngo Molnar 885a5f4374aSIngo Molnar static void __uprobe_unregister(struct uprobe *uprobe) 886a5f4374aSIngo Molnar { 887a5f4374aSIngo Molnar if (!register_for_each_vma(uprobe, false)) 888a5f4374aSIngo Molnar delete_uprobe(uprobe); 889a5f4374aSIngo Molnar 890a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 891a5f4374aSIngo Molnar } 892a5f4374aSIngo Molnar 893a5f4374aSIngo Molnar /* 894a5f4374aSIngo Molnar * uprobe_register - register a probe 895a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 896a5f4374aSIngo Molnar * @offset: offset from the start of the file. 897e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 898a5f4374aSIngo Molnar * 899a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 900a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 901a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 902a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 903a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 904e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 905a5f4374aSIngo Molnar * unregisters. 906a5f4374aSIngo Molnar * 907a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 908a5f4374aSIngo Molnar * else return 0 (success) 909a5f4374aSIngo Molnar */ 910e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 911a5f4374aSIngo Molnar { 912a5f4374aSIngo Molnar struct uprobe *uprobe; 913a5f4374aSIngo Molnar int ret; 914a5f4374aSIngo Molnar 915e3343e6aSSrikar Dronamraju if (!inode || !uc || uc->next) 916a5f4374aSIngo Molnar return -EINVAL; 917a5f4374aSIngo Molnar 918a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 919a5f4374aSIngo Molnar return -EINVAL; 920a5f4374aSIngo Molnar 921a5f4374aSIngo Molnar ret = 0; 922a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 923a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 924a5f4374aSIngo Molnar 925e3343e6aSSrikar Dronamraju if (uprobe && !consumer_add(uprobe, uc)) { 926a5f4374aSIngo Molnar ret = __uprobe_register(uprobe); 927a5f4374aSIngo Molnar if (ret) { 928a5f4374aSIngo Molnar uprobe->consumers = NULL; 929a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 930a5f4374aSIngo Molnar } else { 931900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_RUN_HANDLER; 932a5f4374aSIngo Molnar } 933a5f4374aSIngo Molnar } 934a5f4374aSIngo Molnar 935a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 936a5f4374aSIngo Molnar put_uprobe(uprobe); 937a5f4374aSIngo Molnar 938a5f4374aSIngo Molnar return ret; 939a5f4374aSIngo Molnar } 940a5f4374aSIngo Molnar 941a5f4374aSIngo Molnar /* 942a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 943a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 944a5f4374aSIngo Molnar * @offset: offset from the start of the file. 945e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 946a5f4374aSIngo Molnar */ 947e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 948a5f4374aSIngo Molnar { 949a5f4374aSIngo Molnar struct uprobe *uprobe; 950a5f4374aSIngo Molnar 951e3343e6aSSrikar Dronamraju if (!inode || !uc) 952a5f4374aSIngo Molnar return; 953a5f4374aSIngo Molnar 954a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 955a5f4374aSIngo Molnar if (!uprobe) 956a5f4374aSIngo Molnar return; 957a5f4374aSIngo Molnar 958a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 959a5f4374aSIngo Molnar 960e3343e6aSSrikar Dronamraju if (consumer_del(uprobe, uc)) { 961a5f4374aSIngo Molnar if (!uprobe->consumers) { 962a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 963900771a4SSrikar Dronamraju uprobe->flags &= ~UPROBE_RUN_HANDLER; 964a5f4374aSIngo Molnar } 965a5f4374aSIngo Molnar } 966a5f4374aSIngo Molnar 967a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 968a5f4374aSIngo Molnar if (uprobe) 969a5f4374aSIngo Molnar put_uprobe(uprobe); 970a5f4374aSIngo Molnar } 971a5f4374aSIngo Molnar 972a5f4374aSIngo Molnar /* 973a5f4374aSIngo Molnar * Of all the nodes that correspond to the given inode, return the node 974a5f4374aSIngo Molnar * with the least offset. 975a5f4374aSIngo Molnar */ 976a5f4374aSIngo Molnar static struct rb_node *find_least_offset_node(struct inode *inode) 977a5f4374aSIngo Molnar { 978a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = 0}; 979a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 980a5f4374aSIngo Molnar struct rb_node *close_node = NULL; 981a5f4374aSIngo Molnar struct uprobe *uprobe; 982a5f4374aSIngo Molnar int match; 983a5f4374aSIngo Molnar 984a5f4374aSIngo Molnar while (n) { 985a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 986a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 987a5f4374aSIngo Molnar 988a5f4374aSIngo Molnar if (uprobe->inode == inode) 989a5f4374aSIngo Molnar close_node = n; 990a5f4374aSIngo Molnar 991a5f4374aSIngo Molnar if (!match) 992a5f4374aSIngo Molnar return close_node; 993a5f4374aSIngo Molnar 994a5f4374aSIngo Molnar if (match < 0) 995a5f4374aSIngo Molnar n = n->rb_left; 996a5f4374aSIngo Molnar else 997a5f4374aSIngo Molnar n = n->rb_right; 998a5f4374aSIngo Molnar } 999a5f4374aSIngo Molnar 1000a5f4374aSIngo Molnar return close_node; 1001a5f4374aSIngo Molnar } 1002a5f4374aSIngo Molnar 1003a5f4374aSIngo Molnar /* 1004a5f4374aSIngo Molnar * For a given inode, build a list of probes that need to be inserted. 1005a5f4374aSIngo Molnar */ 1006a5f4374aSIngo Molnar static void build_probe_list(struct inode *inode, struct list_head *head) 1007a5f4374aSIngo Molnar { 1008a5f4374aSIngo Molnar struct uprobe *uprobe; 1009a5f4374aSIngo Molnar unsigned long flags; 1010a5f4374aSIngo Molnar struct rb_node *n; 1011a5f4374aSIngo Molnar 1012a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 1013a5f4374aSIngo Molnar 1014a5f4374aSIngo Molnar n = find_least_offset_node(inode); 1015a5f4374aSIngo Molnar 1016a5f4374aSIngo Molnar for (; n; n = rb_next(n)) { 1017a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 1018a5f4374aSIngo Molnar if (uprobe->inode != inode) 1019a5f4374aSIngo Molnar break; 1020a5f4374aSIngo Molnar 1021a5f4374aSIngo Molnar list_add(&uprobe->pending_list, head); 1022a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 1023a5f4374aSIngo Molnar } 1024a5f4374aSIngo Molnar 1025a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 1026a5f4374aSIngo Molnar } 1027a5f4374aSIngo Molnar 1028a5f4374aSIngo Molnar /* 1029a5f4374aSIngo Molnar * Called from mmap_region. 1030a5f4374aSIngo Molnar * called with mm->mmap_sem acquired. 1031a5f4374aSIngo Molnar * 1032a5f4374aSIngo Molnar * Return -ve no if we fail to insert probes and we cannot 1033a5f4374aSIngo Molnar * bail-out. 1034a5f4374aSIngo Molnar * Return 0 otherwise. i.e: 1035a5f4374aSIngo Molnar * 1036a5f4374aSIngo Molnar * - successful insertion of probes 1037a5f4374aSIngo Molnar * - (or) no possible probes to be inserted. 1038a5f4374aSIngo Molnar * - (or) insertion of probes failed but we can bail-out. 1039a5f4374aSIngo Molnar */ 1040a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1041a5f4374aSIngo Molnar { 1042a5f4374aSIngo Molnar struct list_head tmp_list; 1043a5f4374aSIngo Molnar struct uprobe *uprobe, *u; 1044a5f4374aSIngo Molnar struct inode *inode; 1045682968e0SSrikar Dronamraju int ret, count; 1046a5f4374aSIngo Molnar 1047a5f4374aSIngo Molnar if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) 1048a5f4374aSIngo Molnar return 0; 1049a5f4374aSIngo Molnar 1050a5f4374aSIngo Molnar inode = vma->vm_file->f_mapping->host; 1051a5f4374aSIngo Molnar if (!inode) 1052a5f4374aSIngo Molnar return 0; 1053a5f4374aSIngo Molnar 1054a5f4374aSIngo Molnar INIT_LIST_HEAD(&tmp_list); 1055a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1056a5f4374aSIngo Molnar build_probe_list(inode, &tmp_list); 1057a5f4374aSIngo Molnar 1058a5f4374aSIngo Molnar ret = 0; 1059682968e0SSrikar Dronamraju count = 0; 1060a5f4374aSIngo Molnar 1061a5f4374aSIngo Molnar list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 1062a5f4374aSIngo Molnar loff_t vaddr; 1063a5f4374aSIngo Molnar 1064a5f4374aSIngo Molnar list_del(&uprobe->pending_list); 1065a5f4374aSIngo Molnar if (!ret) { 1066a5f4374aSIngo Molnar vaddr = vma_address(vma, uprobe->offset); 1067682968e0SSrikar Dronamraju 1068682968e0SSrikar Dronamraju if (vaddr < vma->vm_start || vaddr >= vma->vm_end) { 1069682968e0SSrikar Dronamraju put_uprobe(uprobe); 1070682968e0SSrikar Dronamraju continue; 1071a5f4374aSIngo Molnar } 1072682968e0SSrikar Dronamraju 1073682968e0SSrikar Dronamraju ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1074682968e0SSrikar Dronamraju 1075682968e0SSrikar Dronamraju /* Ignore double add: */ 1076682968e0SSrikar Dronamraju if (ret == -EEXIST) { 1077682968e0SSrikar Dronamraju ret = 0; 1078682968e0SSrikar Dronamraju 1079682968e0SSrikar Dronamraju if (!is_swbp_at_addr(vma->vm_mm, vaddr)) 1080682968e0SSrikar Dronamraju continue; 1081682968e0SSrikar Dronamraju 1082682968e0SSrikar Dronamraju /* 1083682968e0SSrikar Dronamraju * Unable to insert a breakpoint, but 1084682968e0SSrikar Dronamraju * breakpoint lies underneath. Increment the 1085682968e0SSrikar Dronamraju * probe count. 1086682968e0SSrikar Dronamraju */ 1087682968e0SSrikar Dronamraju atomic_inc(&vma->vm_mm->uprobes_state.count); 1088682968e0SSrikar Dronamraju } 1089682968e0SSrikar Dronamraju 1090682968e0SSrikar Dronamraju if (!ret) 1091682968e0SSrikar Dronamraju count++; 1092a5f4374aSIngo Molnar } 1093a5f4374aSIngo Molnar put_uprobe(uprobe); 1094a5f4374aSIngo Molnar } 1095a5f4374aSIngo Molnar 1096a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1097a5f4374aSIngo Molnar 1098682968e0SSrikar Dronamraju if (ret) 1099682968e0SSrikar Dronamraju atomic_sub(count, &vma->vm_mm->uprobes_state.count); 1100682968e0SSrikar Dronamraju 1101a5f4374aSIngo Molnar return ret; 1102a5f4374aSIngo Molnar } 1103a5f4374aSIngo Molnar 1104682968e0SSrikar Dronamraju /* 1105682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1106682968e0SSrikar Dronamraju */ 1107cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1108682968e0SSrikar Dronamraju { 1109682968e0SSrikar Dronamraju struct list_head tmp_list; 1110682968e0SSrikar Dronamraju struct uprobe *uprobe, *u; 1111682968e0SSrikar Dronamraju struct inode *inode; 1112682968e0SSrikar Dronamraju 1113682968e0SSrikar Dronamraju if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) 1114682968e0SSrikar Dronamraju return; 1115682968e0SSrikar Dronamraju 1116682968e0SSrikar Dronamraju if (!atomic_read(&vma->vm_mm->uprobes_state.count)) 1117682968e0SSrikar Dronamraju return; 1118682968e0SSrikar Dronamraju 1119682968e0SSrikar Dronamraju inode = vma->vm_file->f_mapping->host; 1120682968e0SSrikar Dronamraju if (!inode) 1121682968e0SSrikar Dronamraju return; 1122682968e0SSrikar Dronamraju 1123682968e0SSrikar Dronamraju INIT_LIST_HEAD(&tmp_list); 1124682968e0SSrikar Dronamraju mutex_lock(uprobes_mmap_hash(inode)); 1125682968e0SSrikar Dronamraju build_probe_list(inode, &tmp_list); 1126682968e0SSrikar Dronamraju 1127682968e0SSrikar Dronamraju list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 1128682968e0SSrikar Dronamraju loff_t vaddr; 1129682968e0SSrikar Dronamraju 1130682968e0SSrikar Dronamraju list_del(&uprobe->pending_list); 1131682968e0SSrikar Dronamraju vaddr = vma_address(vma, uprobe->offset); 1132682968e0SSrikar Dronamraju 1133cbc91f71SSrikar Dronamraju if (vaddr >= start && vaddr < end) { 1134682968e0SSrikar Dronamraju /* 1135682968e0SSrikar Dronamraju * An unregister could have removed the probe before 1136682968e0SSrikar Dronamraju * unmap. So check before we decrement the count. 1137682968e0SSrikar Dronamraju */ 1138682968e0SSrikar Dronamraju if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1) 1139682968e0SSrikar Dronamraju atomic_dec(&vma->vm_mm->uprobes_state.count); 1140682968e0SSrikar Dronamraju } 1141682968e0SSrikar Dronamraju put_uprobe(uprobe); 1142682968e0SSrikar Dronamraju } 1143682968e0SSrikar Dronamraju mutex_unlock(uprobes_mmap_hash(inode)); 1144682968e0SSrikar Dronamraju } 1145682968e0SSrikar Dronamraju 1146d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 1147d4b3b638SSrikar Dronamraju static int xol_add_vma(struct xol_area *area) 1148d4b3b638SSrikar Dronamraju { 1149d4b3b638SSrikar Dronamraju struct mm_struct *mm; 1150d4b3b638SSrikar Dronamraju int ret; 1151d4b3b638SSrikar Dronamraju 1152d4b3b638SSrikar Dronamraju area->page = alloc_page(GFP_HIGHUSER); 1153d4b3b638SSrikar Dronamraju if (!area->page) 1154d4b3b638SSrikar Dronamraju return -ENOMEM; 1155d4b3b638SSrikar Dronamraju 1156d4b3b638SSrikar Dronamraju ret = -EALREADY; 1157d4b3b638SSrikar Dronamraju mm = current->mm; 1158d4b3b638SSrikar Dronamraju 1159d4b3b638SSrikar Dronamraju down_write(&mm->mmap_sem); 1160d4b3b638SSrikar Dronamraju if (mm->uprobes_state.xol_area) 1161d4b3b638SSrikar Dronamraju goto fail; 1162d4b3b638SSrikar Dronamraju 1163d4b3b638SSrikar Dronamraju ret = -ENOMEM; 1164d4b3b638SSrikar Dronamraju 1165d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1166d4b3b638SSrikar Dronamraju area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); 1167d4b3b638SSrikar Dronamraju if (area->vaddr & ~PAGE_MASK) { 1168d4b3b638SSrikar Dronamraju ret = area->vaddr; 1169d4b3b638SSrikar Dronamraju goto fail; 1170d4b3b638SSrikar Dronamraju } 1171d4b3b638SSrikar Dronamraju 1172d4b3b638SSrikar Dronamraju ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1173d4b3b638SSrikar Dronamraju VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); 1174d4b3b638SSrikar Dronamraju if (ret) 1175d4b3b638SSrikar Dronamraju goto fail; 1176d4b3b638SSrikar Dronamraju 1177d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1178d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1179d4b3b638SSrikar Dronamraju ret = 0; 1180d4b3b638SSrikar Dronamraju 1181d4b3b638SSrikar Dronamraju fail: 1182d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1183d4b3b638SSrikar Dronamraju if (ret) 1184d4b3b638SSrikar Dronamraju __free_page(area->page); 1185d4b3b638SSrikar Dronamraju 1186d4b3b638SSrikar Dronamraju return ret; 1187d4b3b638SSrikar Dronamraju } 1188d4b3b638SSrikar Dronamraju 1189d4b3b638SSrikar Dronamraju static struct xol_area *get_xol_area(struct mm_struct *mm) 1190d4b3b638SSrikar Dronamraju { 1191d4b3b638SSrikar Dronamraju struct xol_area *area; 1192d4b3b638SSrikar Dronamraju 1193d4b3b638SSrikar Dronamraju area = mm->uprobes_state.xol_area; 1194d4b3b638SSrikar Dronamraju smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 1195d4b3b638SSrikar Dronamraju 1196d4b3b638SSrikar Dronamraju return area; 1197d4b3b638SSrikar Dronamraju } 1198d4b3b638SSrikar Dronamraju 1199d4b3b638SSrikar Dronamraju /* 1200d4b3b638SSrikar Dronamraju * xol_alloc_area - Allocate process's xol_area. 1201d4b3b638SSrikar Dronamraju * This area will be used for storing instructions for execution out of 1202d4b3b638SSrikar Dronamraju * line. 1203d4b3b638SSrikar Dronamraju * 1204d4b3b638SSrikar Dronamraju * Returns the allocated area or NULL. 1205d4b3b638SSrikar Dronamraju */ 1206d4b3b638SSrikar Dronamraju static struct xol_area *xol_alloc_area(void) 1207d4b3b638SSrikar Dronamraju { 1208d4b3b638SSrikar Dronamraju struct xol_area *area; 1209d4b3b638SSrikar Dronamraju 1210d4b3b638SSrikar Dronamraju area = kzalloc(sizeof(*area), GFP_KERNEL); 1211d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1212d4b3b638SSrikar Dronamraju return NULL; 1213d4b3b638SSrikar Dronamraju 1214d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1215d4b3b638SSrikar Dronamraju 1216d4b3b638SSrikar Dronamraju if (!area->bitmap) 1217d4b3b638SSrikar Dronamraju goto fail; 1218d4b3b638SSrikar Dronamraju 1219d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 1220d4b3b638SSrikar Dronamraju if (!xol_add_vma(area)) 1221d4b3b638SSrikar Dronamraju return area; 1222d4b3b638SSrikar Dronamraju 1223d4b3b638SSrikar Dronamraju fail: 1224d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1225d4b3b638SSrikar Dronamraju kfree(area); 1226d4b3b638SSrikar Dronamraju 1227d4b3b638SSrikar Dronamraju return get_xol_area(current->mm); 1228d4b3b638SSrikar Dronamraju } 1229d4b3b638SSrikar Dronamraju 1230d4b3b638SSrikar Dronamraju /* 1231d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1232d4b3b638SSrikar Dronamraju */ 1233d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1234d4b3b638SSrikar Dronamraju { 1235d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1236d4b3b638SSrikar Dronamraju 1237d4b3b638SSrikar Dronamraju if (!area) 1238d4b3b638SSrikar Dronamraju return; 1239d4b3b638SSrikar Dronamraju 1240d4b3b638SSrikar Dronamraju put_page(area->page); 1241d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1242d4b3b638SSrikar Dronamraju kfree(area); 1243d4b3b638SSrikar Dronamraju } 1244d4b3b638SSrikar Dronamraju 1245d4b3b638SSrikar Dronamraju /* 1246d4b3b638SSrikar Dronamraju * uprobe_reset_state - Free the area allocated for slots. 1247d4b3b638SSrikar Dronamraju */ 1248d4b3b638SSrikar Dronamraju void uprobe_reset_state(struct mm_struct *mm) 1249d4b3b638SSrikar Dronamraju { 1250d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = NULL; 1251682968e0SSrikar Dronamraju atomic_set(&mm->uprobes_state.count, 0); 1252d4b3b638SSrikar Dronamraju } 1253d4b3b638SSrikar Dronamraju 1254d4b3b638SSrikar Dronamraju /* 1255d4b3b638SSrikar Dronamraju * - search for a free slot. 1256d4b3b638SSrikar Dronamraju */ 1257d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1258d4b3b638SSrikar Dronamraju { 1259d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1260d4b3b638SSrikar Dronamraju int slot_nr; 1261d4b3b638SSrikar Dronamraju 1262d4b3b638SSrikar Dronamraju do { 1263d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1264d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1265d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1266d4b3b638SSrikar Dronamraju break; 1267d4b3b638SSrikar Dronamraju 1268d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1269d4b3b638SSrikar Dronamraju continue; 1270d4b3b638SSrikar Dronamraju } 1271d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1272d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1273d4b3b638SSrikar Dronamraju 1274d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1275d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1276d4b3b638SSrikar Dronamraju 1277d4b3b638SSrikar Dronamraju return slot_addr; 1278d4b3b638SSrikar Dronamraju } 1279d4b3b638SSrikar Dronamraju 1280d4b3b638SSrikar Dronamraju /* 1281d4b3b638SSrikar Dronamraju * xol_get_insn_slot - If was not allocated a slot, then 1282d4b3b638SSrikar Dronamraju * allocate a slot. 1283d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1284d4b3b638SSrikar Dronamraju */ 1285d4b3b638SSrikar Dronamraju static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot_addr) 1286d4b3b638SSrikar Dronamraju { 1287d4b3b638SSrikar Dronamraju struct xol_area *area; 1288d4b3b638SSrikar Dronamraju unsigned long offset; 1289d4b3b638SSrikar Dronamraju void *vaddr; 1290d4b3b638SSrikar Dronamraju 1291d4b3b638SSrikar Dronamraju area = get_xol_area(current->mm); 1292d4b3b638SSrikar Dronamraju if (!area) { 1293d4b3b638SSrikar Dronamraju area = xol_alloc_area(); 1294d4b3b638SSrikar Dronamraju if (!area) 1295d4b3b638SSrikar Dronamraju return 0; 1296d4b3b638SSrikar Dronamraju } 1297d4b3b638SSrikar Dronamraju current->utask->xol_vaddr = xol_take_insn_slot(area); 1298d4b3b638SSrikar Dronamraju 1299d4b3b638SSrikar Dronamraju /* 1300d4b3b638SSrikar Dronamraju * Initialize the slot if xol_vaddr points to valid 1301d4b3b638SSrikar Dronamraju * instruction slot. 1302d4b3b638SSrikar Dronamraju */ 1303d4b3b638SSrikar Dronamraju if (unlikely(!current->utask->xol_vaddr)) 1304d4b3b638SSrikar Dronamraju return 0; 1305d4b3b638SSrikar Dronamraju 1306d4b3b638SSrikar Dronamraju current->utask->vaddr = slot_addr; 1307d4b3b638SSrikar Dronamraju offset = current->utask->xol_vaddr & ~PAGE_MASK; 1308d4b3b638SSrikar Dronamraju vaddr = kmap_atomic(area->page); 1309d4b3b638SSrikar Dronamraju memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); 1310d4b3b638SSrikar Dronamraju kunmap_atomic(vaddr); 1311d4b3b638SSrikar Dronamraju 1312d4b3b638SSrikar Dronamraju return current->utask->xol_vaddr; 1313d4b3b638SSrikar Dronamraju } 1314d4b3b638SSrikar Dronamraju 1315d4b3b638SSrikar Dronamraju /* 1316d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1317d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1318d4b3b638SSrikar Dronamraju * subsequent requests. 1319d4b3b638SSrikar Dronamraju */ 1320d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1321d4b3b638SSrikar Dronamraju { 1322d4b3b638SSrikar Dronamraju struct xol_area *area; 1323d4b3b638SSrikar Dronamraju unsigned long vma_end; 1324d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1325d4b3b638SSrikar Dronamraju 1326d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1327d4b3b638SSrikar Dronamraju return; 1328d4b3b638SSrikar Dronamraju 1329d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1330d4b3b638SSrikar Dronamraju 1331d4b3b638SSrikar Dronamraju if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) 1332d4b3b638SSrikar Dronamraju return; 1333d4b3b638SSrikar Dronamraju 1334d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1335d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1336d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1337d4b3b638SSrikar Dronamraju unsigned long offset; 1338d4b3b638SSrikar Dronamraju int slot_nr; 1339d4b3b638SSrikar Dronamraju 1340d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1341d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1342d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1343d4b3b638SSrikar Dronamraju return; 1344d4b3b638SSrikar Dronamraju 1345d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1346d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 1347d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1348d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1349d4b3b638SSrikar Dronamraju 1350d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1351d4b3b638SSrikar Dronamraju } 1352d4b3b638SSrikar Dronamraju } 1353d4b3b638SSrikar Dronamraju 13540326f5a9SSrikar Dronamraju /** 13550326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 13560326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 13570326f5a9SSrikar Dronamraju * instruction. 13580326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 13590326f5a9SSrikar Dronamraju */ 13600326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 13610326f5a9SSrikar Dronamraju { 13620326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 13630326f5a9SSrikar Dronamraju } 13640326f5a9SSrikar Dronamraju 13650326f5a9SSrikar Dronamraju /* 13660326f5a9SSrikar Dronamraju * Called with no locks held. 13670326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 13680326f5a9SSrikar Dronamraju */ 13690326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 13700326f5a9SSrikar Dronamraju { 13710326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13720326f5a9SSrikar Dronamraju 13730326f5a9SSrikar Dronamraju if (!utask) 13740326f5a9SSrikar Dronamraju return; 13750326f5a9SSrikar Dronamraju 13760326f5a9SSrikar Dronamraju if (utask->active_uprobe) 13770326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 13780326f5a9SSrikar Dronamraju 1379d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 13800326f5a9SSrikar Dronamraju kfree(utask); 13810326f5a9SSrikar Dronamraju t->utask = NULL; 13820326f5a9SSrikar Dronamraju } 13830326f5a9SSrikar Dronamraju 13840326f5a9SSrikar Dronamraju /* 13850326f5a9SSrikar Dronamraju * Called in context of a new clone/fork from copy_process. 13860326f5a9SSrikar Dronamraju */ 13870326f5a9SSrikar Dronamraju void uprobe_copy_process(struct task_struct *t) 13880326f5a9SSrikar Dronamraju { 13890326f5a9SSrikar Dronamraju t->utask = NULL; 13900326f5a9SSrikar Dronamraju } 13910326f5a9SSrikar Dronamraju 13920326f5a9SSrikar Dronamraju /* 13930326f5a9SSrikar Dronamraju * Allocate a uprobe_task object for the task. 13940326f5a9SSrikar Dronamraju * Called when the thread hits a breakpoint for the first time. 13950326f5a9SSrikar Dronamraju * 13960326f5a9SSrikar Dronamraju * Returns: 13970326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 13980326f5a9SSrikar Dronamraju * - NULL otherwise 13990326f5a9SSrikar Dronamraju */ 14000326f5a9SSrikar Dronamraju static struct uprobe_task *add_utask(void) 14010326f5a9SSrikar Dronamraju { 14020326f5a9SSrikar Dronamraju struct uprobe_task *utask; 14030326f5a9SSrikar Dronamraju 14040326f5a9SSrikar Dronamraju utask = kzalloc(sizeof *utask, GFP_KERNEL); 14050326f5a9SSrikar Dronamraju if (unlikely(!utask)) 14060326f5a9SSrikar Dronamraju return NULL; 14070326f5a9SSrikar Dronamraju 14080326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 14090326f5a9SSrikar Dronamraju current->utask = utask; 14100326f5a9SSrikar Dronamraju return utask; 14110326f5a9SSrikar Dronamraju } 14120326f5a9SSrikar Dronamraju 14130326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 14140326f5a9SSrikar Dronamraju static int 14150326f5a9SSrikar Dronamraju pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long vaddr) 14160326f5a9SSrikar Dronamraju { 1417d4b3b638SSrikar Dronamraju if (xol_get_insn_slot(uprobe, vaddr) && !arch_uprobe_pre_xol(&uprobe->arch, regs)) 1418d4b3b638SSrikar Dronamraju return 0; 1419d4b3b638SSrikar Dronamraju 14200326f5a9SSrikar Dronamraju return -EFAULT; 14210326f5a9SSrikar Dronamraju } 14220326f5a9SSrikar Dronamraju 14230326f5a9SSrikar Dronamraju /* 14240326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 14250326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 14260326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 14270326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 14280326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 14290326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 14300326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 14310326f5a9SSrikar Dronamraju */ 14320326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 14330326f5a9SSrikar Dronamraju { 14340326f5a9SSrikar Dronamraju struct task_struct *t = current; 14350326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 14360326f5a9SSrikar Dronamraju 14370326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 14380326f5a9SSrikar Dronamraju return false; 14390326f5a9SSrikar Dronamraju 14400326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 14410326f5a9SSrikar Dronamraju 14420326f5a9SSrikar Dronamraju if (signal_pending(t)) { 14430326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 14440326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 14450326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 14460326f5a9SSrikar Dronamraju 14470326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 14480326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 14490326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 14500326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); 14510326f5a9SSrikar Dronamraju } 14520326f5a9SSrikar Dronamraju } 14530326f5a9SSrikar Dronamraju 14540326f5a9SSrikar Dronamraju return true; 14550326f5a9SSrikar Dronamraju } 14560326f5a9SSrikar Dronamraju 14570326f5a9SSrikar Dronamraju /* 14580326f5a9SSrikar Dronamraju * Avoid singlestepping the original instruction if the original instruction 14590326f5a9SSrikar Dronamraju * is a NOP or can be emulated. 14600326f5a9SSrikar Dronamraju */ 14610326f5a9SSrikar Dronamraju static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) 14620326f5a9SSrikar Dronamraju { 14630326f5a9SSrikar Dronamraju if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 14640326f5a9SSrikar Dronamraju return true; 14650326f5a9SSrikar Dronamraju 14660326f5a9SSrikar Dronamraju uprobe->flags &= ~UPROBE_SKIP_SSTEP; 14670326f5a9SSrikar Dronamraju return false; 14680326f5a9SSrikar Dronamraju } 14690326f5a9SSrikar Dronamraju 1470d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 14710326f5a9SSrikar Dronamraju { 14723a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 14733a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 14740326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 14750326f5a9SSrikar Dronamraju 14760326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 14770326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 14783a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 14793a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 14800326f5a9SSrikar Dronamraju struct inode *inode; 14810326f5a9SSrikar Dronamraju loff_t offset; 14820326f5a9SSrikar Dronamraju 14830326f5a9SSrikar Dronamraju inode = vma->vm_file->f_mapping->host; 14840326f5a9SSrikar Dronamraju offset = bp_vaddr - vma->vm_start; 14850326f5a9SSrikar Dronamraju offset += (vma->vm_pgoff << PAGE_SHIFT); 14860326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 14870326f5a9SSrikar Dronamraju } 1488d790d346SOleg Nesterov 1489d790d346SOleg Nesterov if (!uprobe) 1490d790d346SOleg Nesterov *is_swbp = is_swbp_at_addr(mm, bp_vaddr); 1491d790d346SOleg Nesterov } else { 1492d790d346SOleg Nesterov *is_swbp = -EFAULT; 14933a9ea052SOleg Nesterov } 14940326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 14950326f5a9SSrikar Dronamraju 14963a9ea052SOleg Nesterov return uprobe; 14973a9ea052SOleg Nesterov } 14983a9ea052SOleg Nesterov 14993a9ea052SOleg Nesterov /* 15003a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 15013a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 15023a9ea052SOleg Nesterov */ 15033a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 15043a9ea052SOleg Nesterov { 15053a9ea052SOleg Nesterov struct uprobe_task *utask; 15063a9ea052SOleg Nesterov struct uprobe *uprobe; 15073a9ea052SOleg Nesterov unsigned long bp_vaddr; 150856bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 15093a9ea052SOleg Nesterov 15103a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 1511d790d346SOleg Nesterov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 15123a9ea052SOleg Nesterov 15130326f5a9SSrikar Dronamraju if (!uprobe) { 151456bb4cf6SOleg Nesterov if (is_swbp > 0) { 15150326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 15160326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 151756bb4cf6SOleg Nesterov } else { 151856bb4cf6SOleg Nesterov /* 151956bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 152056bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 152156bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 152256bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 152356bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 152456bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 152556bb4cf6SOleg Nesterov */ 152656bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 152756bb4cf6SOleg Nesterov } 15280326f5a9SSrikar Dronamraju return; 15290326f5a9SSrikar Dronamraju } 15300326f5a9SSrikar Dronamraju 15310326f5a9SSrikar Dronamraju utask = current->utask; 15320326f5a9SSrikar Dronamraju if (!utask) { 15330326f5a9SSrikar Dronamraju utask = add_utask(); 15340326f5a9SSrikar Dronamraju /* Cannot allocate; re-execute the instruction. */ 15350326f5a9SSrikar Dronamraju if (!utask) 15360326f5a9SSrikar Dronamraju goto cleanup_ret; 15370326f5a9SSrikar Dronamraju } 15380326f5a9SSrikar Dronamraju utask->active_uprobe = uprobe; 15390326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 15400326f5a9SSrikar Dronamraju if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs)) 15410326f5a9SSrikar Dronamraju goto cleanup_ret; 15420326f5a9SSrikar Dronamraju 15430326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP; 15440326f5a9SSrikar Dronamraju if (!pre_ssout(uprobe, regs, bp_vaddr)) { 15450326f5a9SSrikar Dronamraju user_enable_single_step(current); 15460326f5a9SSrikar Dronamraju return; 15470326f5a9SSrikar Dronamraju } 15480326f5a9SSrikar Dronamraju 15490326f5a9SSrikar Dronamraju cleanup_ret: 15500326f5a9SSrikar Dronamraju if (utask) { 15510326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15520326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 15530326f5a9SSrikar Dronamraju } 15540326f5a9SSrikar Dronamraju if (uprobe) { 15550326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_SKIP_SSTEP)) 15560326f5a9SSrikar Dronamraju 15570326f5a9SSrikar Dronamraju /* 15580326f5a9SSrikar Dronamraju * cannot singlestep; cannot skip instruction; 15590326f5a9SSrikar Dronamraju * re-execute the instruction. 15600326f5a9SSrikar Dronamraju */ 15610326f5a9SSrikar Dronamraju instruction_pointer_set(regs, bp_vaddr); 15620326f5a9SSrikar Dronamraju 15630326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15640326f5a9SSrikar Dronamraju } 15650326f5a9SSrikar Dronamraju } 15660326f5a9SSrikar Dronamraju 15670326f5a9SSrikar Dronamraju /* 15680326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 15690326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 15700326f5a9SSrikar Dronamraju */ 15710326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 15720326f5a9SSrikar Dronamraju { 15730326f5a9SSrikar Dronamraju struct uprobe *uprobe; 15740326f5a9SSrikar Dronamraju 15750326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 15760326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 15770326f5a9SSrikar Dronamraju arch_uprobe_post_xol(&uprobe->arch, regs); 15780326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 15790326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 15800326f5a9SSrikar Dronamraju else 15810326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 15820326f5a9SSrikar Dronamraju 15830326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15840326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15850326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 15860326f5a9SSrikar Dronamraju user_disable_single_step(current); 1587d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 15880326f5a9SSrikar Dronamraju 15890326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 15900326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 15910326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 15920326f5a9SSrikar Dronamraju } 15930326f5a9SSrikar Dronamraju 15940326f5a9SSrikar Dronamraju /* 15950326f5a9SSrikar Dronamraju * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag. (and on 15960326f5a9SSrikar Dronamraju * subsequent probe hits on the thread sets the state to UTASK_BP_HIT) and 15970326f5a9SSrikar Dronamraju * allows the thread to return from interrupt. 15980326f5a9SSrikar Dronamraju * 15990326f5a9SSrikar Dronamraju * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag and 16000326f5a9SSrikar Dronamraju * also sets the state to UTASK_SSTEP_ACK and allows the thread to return from 16010326f5a9SSrikar Dronamraju * interrupt. 16020326f5a9SSrikar Dronamraju * 16030326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 16040326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 16050326f5a9SSrikar Dronamraju */ 16060326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 16070326f5a9SSrikar Dronamraju { 16080326f5a9SSrikar Dronamraju struct uprobe_task *utask; 16090326f5a9SSrikar Dronamraju 16100326f5a9SSrikar Dronamraju utask = current->utask; 16110326f5a9SSrikar Dronamraju if (!utask || utask->state == UTASK_BP_HIT) 16120326f5a9SSrikar Dronamraju handle_swbp(regs); 16130326f5a9SSrikar Dronamraju else 16140326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 16150326f5a9SSrikar Dronamraju } 16160326f5a9SSrikar Dronamraju 16170326f5a9SSrikar Dronamraju /* 16180326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 16190326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 16200326f5a9SSrikar Dronamraju */ 16210326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 16220326f5a9SSrikar Dronamraju { 16230326f5a9SSrikar Dronamraju struct uprobe_task *utask; 16240326f5a9SSrikar Dronamraju 1625682968e0SSrikar Dronamraju if (!current->mm || !atomic_read(¤t->mm->uprobes_state.count)) 1626682968e0SSrikar Dronamraju /* task is currently not uprobed */ 16270326f5a9SSrikar Dronamraju return 0; 16280326f5a9SSrikar Dronamraju 16290326f5a9SSrikar Dronamraju utask = current->utask; 16300326f5a9SSrikar Dronamraju if (utask) 16310326f5a9SSrikar Dronamraju utask->state = UTASK_BP_HIT; 16320326f5a9SSrikar Dronamraju 16330326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 16340326f5a9SSrikar Dronamraju 16350326f5a9SSrikar Dronamraju return 1; 16360326f5a9SSrikar Dronamraju } 16370326f5a9SSrikar Dronamraju 16380326f5a9SSrikar Dronamraju /* 16390326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 16400326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 16410326f5a9SSrikar Dronamraju */ 16420326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 16430326f5a9SSrikar Dronamraju { 16440326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 16450326f5a9SSrikar Dronamraju 16460326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 16470326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 16480326f5a9SSrikar Dronamraju return 0; 16490326f5a9SSrikar Dronamraju 16500326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 16510326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 16520326f5a9SSrikar Dronamraju return 1; 16530326f5a9SSrikar Dronamraju } 16540326f5a9SSrikar Dronamraju 16550326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 16560326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 16570326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 16580326f5a9SSrikar Dronamraju }; 16590326f5a9SSrikar Dronamraju 1660a5f4374aSIngo Molnar static int __init init_uprobes(void) 1661a5f4374aSIngo Molnar { 1662a5f4374aSIngo Molnar int i; 1663a5f4374aSIngo Molnar 1664a5f4374aSIngo Molnar for (i = 0; i < UPROBES_HASH_SZ; i++) { 1665a5f4374aSIngo Molnar mutex_init(&uprobes_mutex[i]); 1666a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 1667a5f4374aSIngo Molnar } 16680326f5a9SSrikar Dronamraju 16690326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 1670a5f4374aSIngo Molnar } 16710326f5a9SSrikar Dronamraju module_init(init_uprobes); 1672a5f4374aSIngo Molnar 1673a5f4374aSIngo Molnar static void __exit exit_uprobes(void) 1674a5f4374aSIngo Molnar { 1675a5f4374aSIngo Molnar } 1676a5f4374aSIngo Molnar module_exit(exit_uprobes); 1677