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 47c5784de2SPeter Zijlstra /* 48c5784de2SPeter Zijlstra * We need separate register/unregister and mmap/munmap lock hashes because 49c5784de2SPeter Zijlstra * of mmap_sem nesting. 50c5784de2SPeter Zijlstra * 51c5784de2SPeter Zijlstra * uprobe_register() needs to install probes on (potentially) all processes 52c5784de2SPeter Zijlstra * and thus needs to acquire multiple mmap_sems (consequtively, not 53c5784de2SPeter Zijlstra * concurrently), whereas uprobe_mmap() is called while holding mmap_sem 54c5784de2SPeter Zijlstra * for the particular process doing the mmap. 55c5784de2SPeter Zijlstra * 56c5784de2SPeter Zijlstra * uprobe_register()->register_for_each_vma() needs to drop/acquire mmap_sem 57c5784de2SPeter Zijlstra * because of lock order against i_mmap_mutex. This means there's a hole in 58c5784de2SPeter Zijlstra * the register vma iteration where a mmap() can happen. 59c5784de2SPeter Zijlstra * 60c5784de2SPeter Zijlstra * Thus uprobe_register() can race with uprobe_mmap() and we can try and 61c5784de2SPeter Zijlstra * install a probe where one is already installed. 62c5784de2SPeter Zijlstra */ 63c5784de2SPeter Zijlstra 64a5f4374aSIngo Molnar /* serialize (un)register */ 65a5f4374aSIngo Molnar static struct mutex uprobes_mutex[UPROBES_HASH_SZ]; 66a5f4374aSIngo Molnar 67a5f4374aSIngo Molnar #define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 68a5f4374aSIngo Molnar 69a5f4374aSIngo Molnar /* serialize uprobe->pending_list */ 70a5f4374aSIngo Molnar static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; 71a5f4374aSIngo Molnar #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 72a5f4374aSIngo Molnar 73a5f4374aSIngo Molnar /* 74a5f4374aSIngo Molnar * uprobe_events allows us to skip the uprobe_mmap if there are no uprobe 75a5f4374aSIngo Molnar * events active at this time. Probably a fine grained per inode count is 76a5f4374aSIngo Molnar * better? 77a5f4374aSIngo Molnar */ 78a5f4374aSIngo Molnar static atomic_t uprobe_events = ATOMIC_INIT(0); 79a5f4374aSIngo Molnar 803ff54efdSSrikar Dronamraju struct uprobe { 813ff54efdSSrikar Dronamraju struct rb_node rb_node; /* node in the rb tree */ 823ff54efdSSrikar Dronamraju atomic_t ref; 833ff54efdSSrikar Dronamraju struct rw_semaphore consumer_rwsem; 843ff54efdSSrikar Dronamraju struct list_head pending_list; 853ff54efdSSrikar Dronamraju struct uprobe_consumer *consumers; 863ff54efdSSrikar Dronamraju struct inode *inode; /* Also hold a ref to inode */ 873ff54efdSSrikar Dronamraju loff_t offset; 883ff54efdSSrikar Dronamraju int flags; 893ff54efdSSrikar Dronamraju struct arch_uprobe arch; 903ff54efdSSrikar Dronamraju }; 913ff54efdSSrikar Dronamraju 92a5f4374aSIngo Molnar /* 93a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 94a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 95a5f4374aSIngo Molnar * changed after breakpoint was inserted. 96a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 97a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 98a5f4374aSIngo Molnar * executable vma. 99a5f4374aSIngo Molnar */ 100a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 101a5f4374aSIngo Molnar { 102a5f4374aSIngo Molnar if (!vma->vm_file) 103a5f4374aSIngo Molnar return false; 104a5f4374aSIngo Molnar 105a5f4374aSIngo Molnar if (!is_register) 106a5f4374aSIngo Molnar return true; 107a5f4374aSIngo Molnar 108ea131377SOleg Nesterov if ((vma->vm_flags & (VM_HUGETLB|VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) 109ea131377SOleg Nesterov == (VM_READ|VM_EXEC)) 110a5f4374aSIngo Molnar return true; 111a5f4374aSIngo Molnar 112a5f4374aSIngo Molnar return false; 113a5f4374aSIngo Molnar } 114a5f4374aSIngo Molnar 115a5f4374aSIngo Molnar static loff_t vma_address(struct vm_area_struct *vma, loff_t offset) 116a5f4374aSIngo Molnar { 117a5f4374aSIngo Molnar loff_t vaddr; 118a5f4374aSIngo Molnar 119a5f4374aSIngo Molnar vaddr = vma->vm_start + offset; 120a5f4374aSIngo Molnar vaddr -= vma->vm_pgoff << PAGE_SHIFT; 121a5f4374aSIngo Molnar 122a5f4374aSIngo Molnar return vaddr; 123a5f4374aSIngo Molnar } 124a5f4374aSIngo Molnar 125a5f4374aSIngo Molnar /** 126a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 127a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 128a5f4374aSIngo Molnar * 129a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 130a5f4374aSIngo Molnar * @page: the cowed page we are replacing by kpage 131a5f4374aSIngo Molnar * @kpage: the modified page we replace page by 132a5f4374aSIngo Molnar * 133a5f4374aSIngo Molnar * Returns 0 on success, -EFAULT on failure. 134a5f4374aSIngo Molnar */ 135a5f4374aSIngo Molnar static int __replace_page(struct vm_area_struct *vma, struct page *page, struct page *kpage) 136a5f4374aSIngo Molnar { 137a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 138a5f4374aSIngo Molnar unsigned long addr; 1395323ce71SOleg Nesterov spinlock_t *ptl; 1405323ce71SOleg Nesterov pte_t *ptep; 141a5f4374aSIngo Molnar 142a5f4374aSIngo Molnar addr = page_address_in_vma(page, vma); 143a5f4374aSIngo Molnar if (addr == -EFAULT) 1445323ce71SOleg Nesterov return -EFAULT; 145a5f4374aSIngo Molnar 1465323ce71SOleg Nesterov ptep = page_check_address(page, mm, addr, &ptl, 0); 147a5f4374aSIngo Molnar if (!ptep) 1485323ce71SOleg Nesterov return -EAGAIN; 149a5f4374aSIngo Molnar 150a5f4374aSIngo Molnar get_page(kpage); 151a5f4374aSIngo Molnar page_add_new_anon_rmap(kpage, vma, addr); 152a5f4374aSIngo Molnar 1537396fa81SSrikar Dronamraju if (!PageAnon(page)) { 1547396fa81SSrikar Dronamraju dec_mm_counter(mm, MM_FILEPAGES); 1557396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1567396fa81SSrikar Dronamraju } 1577396fa81SSrikar Dronamraju 158a5f4374aSIngo Molnar flush_cache_page(vma, addr, pte_pfn(*ptep)); 159a5f4374aSIngo Molnar ptep_clear_flush(vma, addr, ptep); 160a5f4374aSIngo Molnar set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); 161a5f4374aSIngo Molnar 162a5f4374aSIngo Molnar page_remove_rmap(page); 163a5f4374aSIngo Molnar if (!page_mapped(page)) 164a5f4374aSIngo Molnar try_to_free_swap(page); 165a5f4374aSIngo Molnar put_page(page); 166a5f4374aSIngo Molnar pte_unmap_unlock(ptep, ptl); 167a5f4374aSIngo Molnar 1685323ce71SOleg Nesterov return 0; 169a5f4374aSIngo Molnar } 170a5f4374aSIngo Molnar 171a5f4374aSIngo Molnar /** 1725cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 173a5f4374aSIngo Molnar * @insn: instruction to be checked. 1745cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 175a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 176a5f4374aSIngo Molnar */ 1775cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 178a5f4374aSIngo Molnar { 1795cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 180a5f4374aSIngo Molnar } 181a5f4374aSIngo Molnar 182a5f4374aSIngo Molnar /* 183a5f4374aSIngo Molnar * NOTE: 184a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 185a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 186a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 187a5f4374aSIngo Molnar * supported by that architecture then we need to modify read_opcode / 188a5f4374aSIngo Molnar * write_opcode accordingly. This would never be a problem for archs that 189a5f4374aSIngo Molnar * have fixed length instructions. 190a5f4374aSIngo Molnar */ 191a5f4374aSIngo Molnar 192a5f4374aSIngo Molnar /* 193a5f4374aSIngo Molnar * write_opcode - write the opcode at a given virtual address. 194e3343e6aSSrikar Dronamraju * @auprobe: arch breakpointing information. 195a5f4374aSIngo Molnar * @mm: the probed process address space. 196a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 197a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 198a5f4374aSIngo Molnar * 199a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 200a5f4374aSIngo Molnar * mm). 201a5f4374aSIngo Molnar * 202a5f4374aSIngo Molnar * For mm @mm, write the opcode at @vaddr. 203a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 204a5f4374aSIngo Molnar */ 205e3343e6aSSrikar Dronamraju static int write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, 206a5f4374aSIngo Molnar unsigned long vaddr, uprobe_opcode_t opcode) 207a5f4374aSIngo Molnar { 208a5f4374aSIngo Molnar struct page *old_page, *new_page; 209a5f4374aSIngo Molnar struct address_space *mapping; 210a5f4374aSIngo Molnar void *vaddr_old, *vaddr_new; 211a5f4374aSIngo Molnar struct vm_area_struct *vma; 2123ff54efdSSrikar Dronamraju struct uprobe *uprobe; 213a5f4374aSIngo Molnar int ret; 2145323ce71SOleg Nesterov retry: 215a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 216a5f4374aSIngo Molnar ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma); 217a5f4374aSIngo Molnar if (ret <= 0) 218a5f4374aSIngo Molnar return ret; 219a5f4374aSIngo Molnar 220a5f4374aSIngo Molnar ret = -EINVAL; 221a5f4374aSIngo Molnar 222a5f4374aSIngo Molnar /* 223a5f4374aSIngo Molnar * We are interested in text pages only. Our pages of interest 224a5f4374aSIngo Molnar * should be mapped for read and execute only. We desist from 225a5f4374aSIngo Molnar * adding probes in write mapped pages since the breakpoints 226a5f4374aSIngo Molnar * might end up in the file copy. 227a5f4374aSIngo Molnar */ 2285cb4ac3aSSrikar Dronamraju if (!valid_vma(vma, is_swbp_insn(&opcode))) 229a5f4374aSIngo Molnar goto put_out; 230a5f4374aSIngo Molnar 2313ff54efdSSrikar Dronamraju uprobe = container_of(auprobe, struct uprobe, arch); 232a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 233a5f4374aSIngo Molnar if (mapping != vma->vm_file->f_mapping) 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); 253d9c4a30eSOleg Nesterov memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE); 254a5f4374aSIngo Molnar 255a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 256a5f4374aSIngo Molnar kunmap_atomic(vaddr_old); 257a5f4374aSIngo Molnar 258a5f4374aSIngo Molnar ret = anon_vma_prepare(vma); 259a5f4374aSIngo Molnar if (ret) 260a5f4374aSIngo Molnar goto unlock_out; 261a5f4374aSIngo Molnar 262a5f4374aSIngo Molnar lock_page(new_page); 263a5f4374aSIngo Molnar ret = __replace_page(vma, old_page, new_page); 264a5f4374aSIngo Molnar unlock_page(new_page); 265a5f4374aSIngo Molnar 266a5f4374aSIngo Molnar unlock_out: 267a5f4374aSIngo Molnar unlock_page(old_page); 268a5f4374aSIngo Molnar page_cache_release(new_page); 269a5f4374aSIngo Molnar 270a5f4374aSIngo Molnar put_out: 271a5f4374aSIngo Molnar put_page(old_page); 272a5f4374aSIngo Molnar 2735323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 2745323ce71SOleg Nesterov goto retry; 275a5f4374aSIngo Molnar return ret; 276a5f4374aSIngo Molnar } 277a5f4374aSIngo Molnar 278a5f4374aSIngo Molnar /** 279a5f4374aSIngo Molnar * read_opcode - read the opcode at a given virtual address. 280a5f4374aSIngo Molnar * @mm: the probed process address space. 281a5f4374aSIngo Molnar * @vaddr: the virtual address to read the opcode. 282a5f4374aSIngo Molnar * @opcode: location to store the read opcode. 283a5f4374aSIngo Molnar * 284a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 285a5f4374aSIngo Molnar * mm. 286a5f4374aSIngo Molnar * 287a5f4374aSIngo Molnar * For mm @mm, read the opcode at @vaddr and store it in @opcode. 288a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 289a5f4374aSIngo Molnar */ 290a5f4374aSIngo Molnar static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t *opcode) 291a5f4374aSIngo Molnar { 292a5f4374aSIngo Molnar struct page *page; 293a5f4374aSIngo Molnar void *vaddr_new; 294a5f4374aSIngo Molnar int ret; 295a5f4374aSIngo Molnar 296a3d7bb47SOleg Nesterov ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); 297a5f4374aSIngo Molnar if (ret <= 0) 298a5f4374aSIngo Molnar return ret; 299a5f4374aSIngo Molnar 300a5f4374aSIngo Molnar lock_page(page); 301a5f4374aSIngo Molnar vaddr_new = kmap_atomic(page); 302a5f4374aSIngo Molnar vaddr &= ~PAGE_MASK; 3035cb4ac3aSSrikar Dronamraju memcpy(opcode, vaddr_new + vaddr, UPROBE_SWBP_INSN_SIZE); 304a5f4374aSIngo Molnar kunmap_atomic(vaddr_new); 305a5f4374aSIngo Molnar unlock_page(page); 306a5f4374aSIngo Molnar 307a5f4374aSIngo Molnar put_page(page); 308a5f4374aSIngo Molnar 309a5f4374aSIngo Molnar return 0; 310a5f4374aSIngo Molnar } 311a5f4374aSIngo Molnar 3125cb4ac3aSSrikar Dronamraju static int is_swbp_at_addr(struct mm_struct *mm, unsigned long vaddr) 313a5f4374aSIngo Molnar { 314a5f4374aSIngo Molnar uprobe_opcode_t opcode; 315a5f4374aSIngo Molnar int result; 316a5f4374aSIngo Molnar 317c00b2750SOleg Nesterov if (current->mm == mm) { 318c00b2750SOleg Nesterov pagefault_disable(); 319c00b2750SOleg Nesterov result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, 320c00b2750SOleg Nesterov sizeof(opcode)); 321c00b2750SOleg Nesterov pagefault_enable(); 322c00b2750SOleg Nesterov 323c00b2750SOleg Nesterov if (likely(result == 0)) 324c00b2750SOleg Nesterov goto out; 325c00b2750SOleg Nesterov } 326c00b2750SOleg Nesterov 327a5f4374aSIngo Molnar result = read_opcode(mm, vaddr, &opcode); 328a5f4374aSIngo Molnar if (result) 329a5f4374aSIngo Molnar return result; 330c00b2750SOleg Nesterov out: 3315cb4ac3aSSrikar Dronamraju if (is_swbp_insn(&opcode)) 332a5f4374aSIngo Molnar return 1; 333a5f4374aSIngo Molnar 334a5f4374aSIngo Molnar return 0; 335a5f4374aSIngo Molnar } 336a5f4374aSIngo Molnar 337a5f4374aSIngo Molnar /** 3385cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 339e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 340a5f4374aSIngo Molnar * @mm: the probed process address space. 341a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 342a5f4374aSIngo Molnar * 343a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 344a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 345a5f4374aSIngo Molnar */ 3465cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 347a5f4374aSIngo Molnar { 348a5f4374aSIngo Molnar int result; 349c5784de2SPeter Zijlstra /* 350c5784de2SPeter Zijlstra * See the comment near uprobes_hash(). 351c5784de2SPeter Zijlstra */ 3525cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 353a5f4374aSIngo Molnar if (result == 1) 354a5f4374aSIngo Molnar return -EEXIST; 355a5f4374aSIngo Molnar 356a5f4374aSIngo Molnar if (result) 357a5f4374aSIngo Molnar return result; 358a5f4374aSIngo Molnar 3595cb4ac3aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, UPROBE_SWBP_INSN); 360a5f4374aSIngo Molnar } 361a5f4374aSIngo Molnar 362a5f4374aSIngo Molnar /** 363a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 364a5f4374aSIngo Molnar * @mm: the probed process address space. 365e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 366a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 367a5f4374aSIngo Molnar * @verify: if true, verify existance of breakpoint instruction. 368a5f4374aSIngo Molnar * 369a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 370a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 371a5f4374aSIngo Molnar */ 372a5f4374aSIngo Molnar int __weak 373e3343e6aSSrikar Dronamraju set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, bool verify) 374a5f4374aSIngo Molnar { 375a5f4374aSIngo Molnar if (verify) { 376a5f4374aSIngo Molnar int result; 377a5f4374aSIngo Molnar 3785cb4ac3aSSrikar Dronamraju result = is_swbp_at_addr(mm, vaddr); 379a5f4374aSIngo Molnar if (!result) 380a5f4374aSIngo Molnar return -EINVAL; 381a5f4374aSIngo Molnar 382a5f4374aSIngo Molnar if (result != 1) 383a5f4374aSIngo Molnar return result; 384a5f4374aSIngo Molnar } 385e3343e6aSSrikar Dronamraju return write_opcode(auprobe, mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); 386a5f4374aSIngo Molnar } 387a5f4374aSIngo Molnar 388a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 389a5f4374aSIngo Molnar { 390a5f4374aSIngo Molnar if (l->inode < r->inode) 391a5f4374aSIngo Molnar return -1; 392a5f4374aSIngo Molnar 393a5f4374aSIngo Molnar if (l->inode > r->inode) 394a5f4374aSIngo Molnar return 1; 395a5f4374aSIngo Molnar 396a5f4374aSIngo Molnar if (l->offset < r->offset) 397a5f4374aSIngo Molnar return -1; 398a5f4374aSIngo Molnar 399a5f4374aSIngo Molnar if (l->offset > r->offset) 400a5f4374aSIngo Molnar return 1; 401a5f4374aSIngo Molnar 402a5f4374aSIngo Molnar return 0; 403a5f4374aSIngo Molnar } 404a5f4374aSIngo Molnar 405a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 406a5f4374aSIngo Molnar { 407a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 408a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 409a5f4374aSIngo Molnar struct uprobe *uprobe; 410a5f4374aSIngo Molnar int match; 411a5f4374aSIngo Molnar 412a5f4374aSIngo Molnar while (n) { 413a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 414a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 415a5f4374aSIngo Molnar if (!match) { 416a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 417a5f4374aSIngo Molnar return uprobe; 418a5f4374aSIngo Molnar } 419a5f4374aSIngo Molnar 420a5f4374aSIngo Molnar if (match < 0) 421a5f4374aSIngo Molnar n = n->rb_left; 422a5f4374aSIngo Molnar else 423a5f4374aSIngo Molnar n = n->rb_right; 424a5f4374aSIngo Molnar } 425a5f4374aSIngo Molnar return NULL; 426a5f4374aSIngo Molnar } 427a5f4374aSIngo Molnar 428a5f4374aSIngo Molnar /* 429a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 430a5f4374aSIngo Molnar * Acquires uprobes_treelock 431a5f4374aSIngo Molnar */ 432a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 433a5f4374aSIngo Molnar { 434a5f4374aSIngo Molnar struct uprobe *uprobe; 435a5f4374aSIngo Molnar unsigned long flags; 436a5f4374aSIngo Molnar 437a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 438a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 439a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 440a5f4374aSIngo Molnar 441a5f4374aSIngo Molnar return uprobe; 442a5f4374aSIngo Molnar } 443a5f4374aSIngo Molnar 444a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 445a5f4374aSIngo Molnar { 446a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 447a5f4374aSIngo Molnar struct rb_node *parent = NULL; 448a5f4374aSIngo Molnar struct uprobe *u; 449a5f4374aSIngo Molnar int match; 450a5f4374aSIngo Molnar 451a5f4374aSIngo Molnar while (*p) { 452a5f4374aSIngo Molnar parent = *p; 453a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 454a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 455a5f4374aSIngo Molnar if (!match) { 456a5f4374aSIngo Molnar atomic_inc(&u->ref); 457a5f4374aSIngo Molnar return u; 458a5f4374aSIngo Molnar } 459a5f4374aSIngo Molnar 460a5f4374aSIngo Molnar if (match < 0) 461a5f4374aSIngo Molnar p = &parent->rb_left; 462a5f4374aSIngo Molnar else 463a5f4374aSIngo Molnar p = &parent->rb_right; 464a5f4374aSIngo Molnar 465a5f4374aSIngo Molnar } 466a5f4374aSIngo Molnar 467a5f4374aSIngo Molnar u = NULL; 468a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 469a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 470a5f4374aSIngo Molnar /* get access + creation ref */ 471a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 472a5f4374aSIngo Molnar 473a5f4374aSIngo Molnar return u; 474a5f4374aSIngo Molnar } 475a5f4374aSIngo Molnar 476a5f4374aSIngo Molnar /* 477a5f4374aSIngo Molnar * Acquire uprobes_treelock. 478a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 479a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 480a5f4374aSIngo Molnar * 481a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 482a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 483a5f4374aSIngo Molnar */ 484a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 485a5f4374aSIngo Molnar { 486a5f4374aSIngo Molnar unsigned long flags; 487a5f4374aSIngo Molnar struct uprobe *u; 488a5f4374aSIngo Molnar 489a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 490a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 491a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 492a5f4374aSIngo Molnar 4930326f5a9SSrikar Dronamraju /* For now assume that the instruction need not be single-stepped */ 4940326f5a9SSrikar Dronamraju uprobe->flags |= UPROBE_SKIP_SSTEP; 4950326f5a9SSrikar Dronamraju 496a5f4374aSIngo Molnar return u; 497a5f4374aSIngo Molnar } 498a5f4374aSIngo Molnar 499a5f4374aSIngo Molnar static void put_uprobe(struct uprobe *uprobe) 500a5f4374aSIngo Molnar { 501a5f4374aSIngo Molnar if (atomic_dec_and_test(&uprobe->ref)) 502a5f4374aSIngo Molnar kfree(uprobe); 503a5f4374aSIngo Molnar } 504a5f4374aSIngo Molnar 505a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 506a5f4374aSIngo Molnar { 507a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 508a5f4374aSIngo Molnar 509a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 510a5f4374aSIngo Molnar if (!uprobe) 511a5f4374aSIngo Molnar return NULL; 512a5f4374aSIngo Molnar 513a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 514a5f4374aSIngo Molnar uprobe->offset = offset; 515a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 516a5f4374aSIngo Molnar 517a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 518a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 519a5f4374aSIngo Molnar 520a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 521a5f4374aSIngo Molnar if (cur_uprobe) { 522a5f4374aSIngo Molnar kfree(uprobe); 523a5f4374aSIngo Molnar uprobe = cur_uprobe; 524a5f4374aSIngo Molnar iput(inode); 525a5f4374aSIngo Molnar } else { 526a5f4374aSIngo Molnar atomic_inc(&uprobe_events); 527a5f4374aSIngo Molnar } 528a5f4374aSIngo Molnar 529a5f4374aSIngo Molnar return uprobe; 530a5f4374aSIngo Molnar } 531a5f4374aSIngo Molnar 5320326f5a9SSrikar Dronamraju static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 5330326f5a9SSrikar Dronamraju { 5340326f5a9SSrikar Dronamraju struct uprobe_consumer *uc; 5350326f5a9SSrikar Dronamraju 5360326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_RUN_HANDLER)) 5370326f5a9SSrikar Dronamraju return; 5380326f5a9SSrikar Dronamraju 5390326f5a9SSrikar Dronamraju down_read(&uprobe->consumer_rwsem); 5400326f5a9SSrikar Dronamraju for (uc = uprobe->consumers; uc; uc = uc->next) { 5410326f5a9SSrikar Dronamraju if (!uc->filter || uc->filter(uc, current)) 5420326f5a9SSrikar Dronamraju uc->handler(uc, regs); 5430326f5a9SSrikar Dronamraju } 5440326f5a9SSrikar Dronamraju up_read(&uprobe->consumer_rwsem); 5450326f5a9SSrikar Dronamraju } 5460326f5a9SSrikar Dronamraju 547a5f4374aSIngo Molnar /* Returns the previous consumer */ 548a5f4374aSIngo Molnar static struct uprobe_consumer * 549e3343e6aSSrikar Dronamraju consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 550a5f4374aSIngo Molnar { 551a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 552e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 553e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 554a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 555a5f4374aSIngo Molnar 556e3343e6aSSrikar Dronamraju return uc->next; 557a5f4374aSIngo Molnar } 558a5f4374aSIngo Molnar 559a5f4374aSIngo Molnar /* 560e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 561e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 562a5f4374aSIngo Molnar * or return false. 563a5f4374aSIngo Molnar */ 564e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 565a5f4374aSIngo Molnar { 566a5f4374aSIngo Molnar struct uprobe_consumer **con; 567a5f4374aSIngo Molnar bool ret = false; 568a5f4374aSIngo Molnar 569a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 570a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 571e3343e6aSSrikar Dronamraju if (*con == uc) { 572e3343e6aSSrikar Dronamraju *con = uc->next; 573a5f4374aSIngo Molnar ret = true; 574a5f4374aSIngo Molnar break; 575a5f4374aSIngo Molnar } 576a5f4374aSIngo Molnar } 577a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 578a5f4374aSIngo Molnar 579a5f4374aSIngo Molnar return ret; 580a5f4374aSIngo Molnar } 581a5f4374aSIngo Molnar 582e3343e6aSSrikar Dronamraju static int 583d436615eSOleg Nesterov __copy_insn(struct address_space *mapping, struct file *filp, char *insn, 584a5f4374aSIngo Molnar unsigned long nbytes, unsigned long offset) 585a5f4374aSIngo Molnar { 586a5f4374aSIngo Molnar struct page *page; 587a5f4374aSIngo Molnar void *vaddr; 588a5f4374aSIngo Molnar unsigned long off1; 589a5f4374aSIngo Molnar unsigned long idx; 590a5f4374aSIngo Molnar 591a5f4374aSIngo Molnar if (!filp) 592a5f4374aSIngo Molnar return -EINVAL; 593a5f4374aSIngo Molnar 594cc359d18SOleg Nesterov if (!mapping->a_ops->readpage) 595cc359d18SOleg Nesterov return -EIO; 596cc359d18SOleg Nesterov 597a5f4374aSIngo Molnar idx = (unsigned long)(offset >> PAGE_CACHE_SHIFT); 598a5f4374aSIngo Molnar off1 = offset &= ~PAGE_MASK; 599a5f4374aSIngo Molnar 600a5f4374aSIngo Molnar /* 601a5f4374aSIngo Molnar * Ensure that the page that has the original instruction is 602a5f4374aSIngo Molnar * populated and in page-cache. 603a5f4374aSIngo Molnar */ 604a5f4374aSIngo Molnar page = read_mapping_page(mapping, idx, filp); 605a5f4374aSIngo Molnar if (IS_ERR(page)) 606a5f4374aSIngo Molnar return PTR_ERR(page); 607a5f4374aSIngo Molnar 608a5f4374aSIngo Molnar vaddr = kmap_atomic(page); 609a5f4374aSIngo Molnar memcpy(insn, vaddr + off1, nbytes); 610a5f4374aSIngo Molnar kunmap_atomic(vaddr); 611a5f4374aSIngo Molnar page_cache_release(page); 612a5f4374aSIngo Molnar 613a5f4374aSIngo Molnar return 0; 614a5f4374aSIngo Molnar } 615a5f4374aSIngo Molnar 616d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 617a5f4374aSIngo Molnar { 618a5f4374aSIngo Molnar struct address_space *mapping; 619a5f4374aSIngo Molnar unsigned long nbytes; 620a5f4374aSIngo Molnar int bytes; 621a5f4374aSIngo Molnar 622d436615eSOleg Nesterov nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); 623a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 624a5f4374aSIngo Molnar 625a5f4374aSIngo Molnar /* Instruction at end of binary; copy only available bytes */ 626a5f4374aSIngo Molnar if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) 627a5f4374aSIngo Molnar bytes = uprobe->inode->i_size - uprobe->offset; 628a5f4374aSIngo Molnar else 629a5f4374aSIngo Molnar bytes = MAX_UINSN_BYTES; 630a5f4374aSIngo Molnar 631a5f4374aSIngo Molnar /* Instruction at the page-boundary; copy bytes in second page */ 632a5f4374aSIngo Molnar if (nbytes < bytes) { 633fc36f595SOleg Nesterov int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, 634fc36f595SOleg Nesterov bytes - nbytes, uprobe->offset + nbytes); 635fc36f595SOleg Nesterov if (err) 636fc36f595SOleg Nesterov return err; 637a5f4374aSIngo Molnar bytes = nbytes; 638a5f4374aSIngo Molnar } 639d436615eSOleg Nesterov return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); 640a5f4374aSIngo Molnar } 641a5f4374aSIngo Molnar 642682968e0SSrikar Dronamraju /* 643682968e0SSrikar Dronamraju * How mm->uprobes_state.count gets updated 644682968e0SSrikar Dronamraju * uprobe_mmap() increments the count if 645682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 646682968e0SSrikar Dronamraju * - it cannot add a breakpoint, but sees that there is a underlying 647682968e0SSrikar Dronamraju * breakpoint (via a is_swbp_at_addr()). 648682968e0SSrikar Dronamraju * 649682968e0SSrikar Dronamraju * uprobe_munmap() decrements the count if 650682968e0SSrikar Dronamraju * - it sees a underlying breakpoint, (via is_swbp_at_addr) 651682968e0SSrikar Dronamraju * (Subsequent uprobe_unregister wouldnt find the breakpoint 652682968e0SSrikar Dronamraju * unless a uprobe_mmap kicks in, since the old vma would be 653682968e0SSrikar Dronamraju * dropped just after uprobe_munmap.) 654682968e0SSrikar Dronamraju * 655682968e0SSrikar Dronamraju * uprobe_register increments the count if: 656682968e0SSrikar Dronamraju * - it successfully adds a breakpoint. 657682968e0SSrikar Dronamraju * 658682968e0SSrikar Dronamraju * uprobe_unregister decrements the count if: 659682968e0SSrikar Dronamraju * - it sees a underlying breakpoint and removes successfully. 660682968e0SSrikar Dronamraju * (via is_swbp_at_addr) 661682968e0SSrikar Dronamraju * (Subsequent uprobe_munmap wouldnt find the breakpoint 662682968e0SSrikar Dronamraju * since there is no underlying breakpoint after the 663682968e0SSrikar Dronamraju * breakpoint removal.) 664682968e0SSrikar Dronamraju */ 665e3343e6aSSrikar Dronamraju static int 666e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 667816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 668a5f4374aSIngo Molnar { 669a5f4374aSIngo Molnar int ret; 670a5f4374aSIngo Molnar 671a5f4374aSIngo Molnar /* 672a5f4374aSIngo Molnar * If probe is being deleted, unregister thread could be done with 673a5f4374aSIngo Molnar * the vma-rmap-walk through. Adding a probe now can be fatal since 674a5f4374aSIngo Molnar * nobody will be able to cleanup. Also we could be from fork or 675a5f4374aSIngo Molnar * mremap path, where the probe might have already been inserted. 676a5f4374aSIngo Molnar * Hence behave as if probe already existed. 677a5f4374aSIngo Molnar */ 678a5f4374aSIngo Molnar if (!uprobe->consumers) 679a5f4374aSIngo Molnar return -EEXIST; 680a5f4374aSIngo Molnar 681900771a4SSrikar Dronamraju if (!(uprobe->flags & UPROBE_COPY_INSN)) { 682d436615eSOleg Nesterov ret = copy_insn(uprobe, vma->vm_file); 683a5f4374aSIngo Molnar if (ret) 684a5f4374aSIngo Molnar return ret; 685a5f4374aSIngo Molnar 6865cb4ac3aSSrikar Dronamraju if (is_swbp_insn((uprobe_opcode_t *)uprobe->arch.insn)) 687c1914a09SOleg Nesterov return -ENOTSUPP; 688a5f4374aSIngo Molnar 689816c03fbSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 690a5f4374aSIngo Molnar if (ret) 691a5f4374aSIngo Molnar return ret; 692a5f4374aSIngo Molnar 693d9c4a30eSOleg Nesterov /* write_opcode() assumes we don't cross page boundary */ 694d9c4a30eSOleg Nesterov BUG_ON((uprobe->offset & ~PAGE_MASK) + 695d9c4a30eSOleg Nesterov UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 696d9c4a30eSOleg Nesterov 697900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_COPY_INSN; 698a5f4374aSIngo Molnar } 699682968e0SSrikar Dronamraju 700682968e0SSrikar Dronamraju /* 701682968e0SSrikar Dronamraju * Ideally, should be updating the probe count after the breakpoint 702682968e0SSrikar Dronamraju * has been successfully inserted. However a thread could hit the 703682968e0SSrikar Dronamraju * breakpoint we just inserted even before the probe count is 704682968e0SSrikar Dronamraju * incremented. If this is the first breakpoint placed, breakpoint 705682968e0SSrikar Dronamraju * notifier might ignore uprobes and pass the trap to the thread. 706682968e0SSrikar Dronamraju * Hence increment before and decrement on failure. 707682968e0SSrikar Dronamraju */ 708682968e0SSrikar Dronamraju atomic_inc(&mm->uprobes_state.count); 709816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 710682968e0SSrikar Dronamraju if (ret) 711682968e0SSrikar Dronamraju atomic_dec(&mm->uprobes_state.count); 712a5f4374aSIngo Molnar 713a5f4374aSIngo Molnar return ret; 714a5f4374aSIngo Molnar } 715a5f4374aSIngo Molnar 716e3343e6aSSrikar Dronamraju static void 717816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 718a5f4374aSIngo Molnar { 719816c03fbSOleg Nesterov if (!set_orig_insn(&uprobe->arch, mm, vaddr, true)) 720682968e0SSrikar Dronamraju atomic_dec(&mm->uprobes_state.count); 721a5f4374aSIngo Molnar } 722a5f4374aSIngo Molnar 7230326f5a9SSrikar Dronamraju /* 724778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 725778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 726778b032dSOleg Nesterov * See find_active_uprobe(). 7270326f5a9SSrikar Dronamraju */ 728a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 729a5f4374aSIngo Molnar { 730a5f4374aSIngo Molnar unsigned long flags; 731a5f4374aSIngo Molnar 732a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 733a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 734a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 735a5f4374aSIngo Molnar iput(uprobe->inode); 736a5f4374aSIngo Molnar put_uprobe(uprobe); 737a5f4374aSIngo Molnar atomic_dec(&uprobe_events); 738a5f4374aSIngo Molnar } 739a5f4374aSIngo Molnar 74026872090SOleg Nesterov struct map_info { 74126872090SOleg Nesterov struct map_info *next; 74226872090SOleg Nesterov struct mm_struct *mm; 743816c03fbSOleg Nesterov unsigned long vaddr; 74426872090SOleg Nesterov }; 74526872090SOleg Nesterov 74626872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 747a5f4374aSIngo Molnar { 74826872090SOleg Nesterov struct map_info *next = info->next; 74926872090SOleg Nesterov kfree(info); 75026872090SOleg Nesterov return next; 75126872090SOleg Nesterov } 75226872090SOleg Nesterov 75326872090SOleg Nesterov static struct map_info * 75426872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 75526872090SOleg Nesterov { 75626872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 757a5f4374aSIngo Molnar struct prio_tree_iter iter; 758a5f4374aSIngo Molnar struct vm_area_struct *vma; 75926872090SOleg Nesterov struct map_info *curr = NULL; 76026872090SOleg Nesterov struct map_info *prev = NULL; 76126872090SOleg Nesterov struct map_info *info; 76226872090SOleg Nesterov int more = 0; 763a5f4374aSIngo Molnar 76426872090SOleg Nesterov again: 76526872090SOleg Nesterov mutex_lock(&mapping->i_mmap_mutex); 766a5f4374aSIngo Molnar vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 767a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 768a5f4374aSIngo Molnar continue; 769a5f4374aSIngo Molnar 7707a5bfb66SOleg Nesterov if (!prev && !more) { 7717a5bfb66SOleg Nesterov /* 7727a5bfb66SOleg Nesterov * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through 7737a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 7747a5bfb66SOleg Nesterov */ 7757a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 7767a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 7777a5bfb66SOleg Nesterov if (prev) 7787a5bfb66SOleg Nesterov prev->next = NULL; 7797a5bfb66SOleg Nesterov } 78026872090SOleg Nesterov if (!prev) { 78126872090SOleg Nesterov more++; 78226872090SOleg Nesterov continue; 783a5f4374aSIngo Molnar } 784a5f4374aSIngo Molnar 78526872090SOleg Nesterov if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) 78626872090SOleg Nesterov continue; 787a5f4374aSIngo Molnar 78826872090SOleg Nesterov info = prev; 78926872090SOleg Nesterov prev = prev->next; 79026872090SOleg Nesterov info->next = curr; 79126872090SOleg Nesterov curr = info; 79226872090SOleg Nesterov 79326872090SOleg Nesterov info->mm = vma->vm_mm; 79426872090SOleg Nesterov info->vaddr = vma_address(vma, offset); 795a5f4374aSIngo Molnar } 796a5f4374aSIngo Molnar mutex_unlock(&mapping->i_mmap_mutex); 797a5f4374aSIngo Molnar 79826872090SOleg Nesterov if (!more) 79926872090SOleg Nesterov goto out; 800a5f4374aSIngo Molnar 80126872090SOleg Nesterov prev = curr; 80226872090SOleg Nesterov while (curr) { 80326872090SOleg Nesterov mmput(curr->mm); 80426872090SOleg Nesterov curr = curr->next; 80526872090SOleg Nesterov } 80626872090SOleg Nesterov 80726872090SOleg Nesterov do { 80826872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 80926872090SOleg Nesterov if (!info) { 81026872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 81126872090SOleg Nesterov goto out; 81226872090SOleg Nesterov } 81326872090SOleg Nesterov info->next = prev; 81426872090SOleg Nesterov prev = info; 81526872090SOleg Nesterov } while (--more); 81626872090SOleg Nesterov 81726872090SOleg Nesterov goto again; 81826872090SOleg Nesterov out: 81926872090SOleg Nesterov while (prev) 82026872090SOleg Nesterov prev = free_map_info(prev); 82126872090SOleg Nesterov return curr; 822a5f4374aSIngo Molnar } 823a5f4374aSIngo Molnar 824a5f4374aSIngo Molnar static int register_for_each_vma(struct uprobe *uprobe, bool is_register) 825a5f4374aSIngo Molnar { 82626872090SOleg Nesterov struct map_info *info; 82726872090SOleg Nesterov int err = 0; 82826872090SOleg Nesterov 82926872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 83026872090SOleg Nesterov uprobe->offset, is_register); 83126872090SOleg Nesterov if (IS_ERR(info)) 83226872090SOleg Nesterov return PTR_ERR(info); 83326872090SOleg Nesterov 83426872090SOleg Nesterov while (info) { 83526872090SOleg Nesterov struct mm_struct *mm = info->mm; 836a5f4374aSIngo Molnar struct vm_area_struct *vma; 837a5f4374aSIngo Molnar 83826872090SOleg Nesterov if (err) 83926872090SOleg Nesterov goto free; 840a5f4374aSIngo Molnar 84177fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 84226872090SOleg Nesterov vma = find_vma(mm, (unsigned long)info->vaddr); 84326872090SOleg Nesterov if (!vma || !valid_vma(vma, is_register)) 84426872090SOleg Nesterov goto unlock; 84526872090SOleg Nesterov 846a5f4374aSIngo Molnar if (vma->vm_file->f_mapping->host != uprobe->inode || 847816c03fbSOleg Nesterov vma_address(vma, uprobe->offset) != info->vaddr) 84826872090SOleg Nesterov goto unlock; 849a5f4374aSIngo Molnar 850a5f4374aSIngo Molnar if (is_register) { 85126872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 852c5784de2SPeter Zijlstra /* 853c5784de2SPeter Zijlstra * We can race against uprobe_mmap(), see the 854c5784de2SPeter Zijlstra * comment near uprobe_hash(). 855c5784de2SPeter Zijlstra */ 85626872090SOleg Nesterov if (err == -EEXIST) 85726872090SOleg Nesterov err = 0; 85826872090SOleg Nesterov } else { 85926872090SOleg Nesterov remove_breakpoint(uprobe, mm, info->vaddr); 860a5f4374aSIngo Molnar } 86126872090SOleg Nesterov unlock: 86226872090SOleg Nesterov up_write(&mm->mmap_sem); 86326872090SOleg Nesterov free: 86426872090SOleg Nesterov mmput(mm); 86526872090SOleg Nesterov info = free_map_info(info); 866a5f4374aSIngo Molnar } 867a5f4374aSIngo Molnar 86826872090SOleg Nesterov return err; 869a5f4374aSIngo Molnar } 870a5f4374aSIngo Molnar 871a5f4374aSIngo Molnar static int __uprobe_register(struct uprobe *uprobe) 872a5f4374aSIngo Molnar { 873a5f4374aSIngo Molnar return register_for_each_vma(uprobe, true); 874a5f4374aSIngo Molnar } 875a5f4374aSIngo Molnar 876a5f4374aSIngo Molnar static void __uprobe_unregister(struct uprobe *uprobe) 877a5f4374aSIngo Molnar { 878a5f4374aSIngo Molnar if (!register_for_each_vma(uprobe, false)) 879a5f4374aSIngo Molnar delete_uprobe(uprobe); 880a5f4374aSIngo Molnar 881a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 882a5f4374aSIngo Molnar } 883a5f4374aSIngo Molnar 884a5f4374aSIngo Molnar /* 885a5f4374aSIngo Molnar * uprobe_register - register a probe 886a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 887a5f4374aSIngo Molnar * @offset: offset from the start of the file. 888e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 889a5f4374aSIngo Molnar * 890a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 891a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 892a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 893a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 894a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 895e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 896a5f4374aSIngo Molnar * unregisters. 897a5f4374aSIngo Molnar * 898a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 899a5f4374aSIngo Molnar * else return 0 (success) 900a5f4374aSIngo Molnar */ 901e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 902a5f4374aSIngo Molnar { 903a5f4374aSIngo Molnar struct uprobe *uprobe; 904a5f4374aSIngo Molnar int ret; 905a5f4374aSIngo Molnar 906e3343e6aSSrikar Dronamraju if (!inode || !uc || uc->next) 907a5f4374aSIngo Molnar return -EINVAL; 908a5f4374aSIngo Molnar 909a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 910a5f4374aSIngo Molnar return -EINVAL; 911a5f4374aSIngo Molnar 912a5f4374aSIngo Molnar ret = 0; 913a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 914a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 915a5f4374aSIngo Molnar 916e3343e6aSSrikar Dronamraju if (uprobe && !consumer_add(uprobe, uc)) { 917a5f4374aSIngo Molnar ret = __uprobe_register(uprobe); 918a5f4374aSIngo Molnar if (ret) { 919a5f4374aSIngo Molnar uprobe->consumers = NULL; 920a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 921a5f4374aSIngo Molnar } else { 922900771a4SSrikar Dronamraju uprobe->flags |= UPROBE_RUN_HANDLER; 923a5f4374aSIngo Molnar } 924a5f4374aSIngo Molnar } 925a5f4374aSIngo Molnar 926a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 927a5f4374aSIngo Molnar put_uprobe(uprobe); 928a5f4374aSIngo Molnar 929a5f4374aSIngo Molnar return ret; 930a5f4374aSIngo Molnar } 931a5f4374aSIngo Molnar 932a5f4374aSIngo Molnar /* 933a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 934a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 935a5f4374aSIngo Molnar * @offset: offset from the start of the file. 936e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 937a5f4374aSIngo Molnar */ 938e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 939a5f4374aSIngo Molnar { 940a5f4374aSIngo Molnar struct uprobe *uprobe; 941a5f4374aSIngo Molnar 942e3343e6aSSrikar Dronamraju if (!inode || !uc) 943a5f4374aSIngo Molnar return; 944a5f4374aSIngo Molnar 945a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 946a5f4374aSIngo Molnar if (!uprobe) 947a5f4374aSIngo Molnar return; 948a5f4374aSIngo Molnar 949a5f4374aSIngo Molnar mutex_lock(uprobes_hash(inode)); 950a5f4374aSIngo Molnar 951e3343e6aSSrikar Dronamraju if (consumer_del(uprobe, uc)) { 952a5f4374aSIngo Molnar if (!uprobe->consumers) { 953a5f4374aSIngo Molnar __uprobe_unregister(uprobe); 954900771a4SSrikar Dronamraju uprobe->flags &= ~UPROBE_RUN_HANDLER; 955a5f4374aSIngo Molnar } 956a5f4374aSIngo Molnar } 957a5f4374aSIngo Molnar 958a5f4374aSIngo Molnar mutex_unlock(uprobes_hash(inode)); 959a5f4374aSIngo Molnar if (uprobe) 960a5f4374aSIngo Molnar put_uprobe(uprobe); 961a5f4374aSIngo Molnar } 962a5f4374aSIngo Molnar 963a5f4374aSIngo Molnar /* 964a5f4374aSIngo Molnar * Of all the nodes that correspond to the given inode, return the node 965a5f4374aSIngo Molnar * with the least offset. 966a5f4374aSIngo Molnar */ 967a5f4374aSIngo Molnar static struct rb_node *find_least_offset_node(struct inode *inode) 968a5f4374aSIngo Molnar { 969a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = 0}; 970a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 971a5f4374aSIngo Molnar struct rb_node *close_node = NULL; 972a5f4374aSIngo Molnar struct uprobe *uprobe; 973a5f4374aSIngo Molnar int match; 974a5f4374aSIngo Molnar 975a5f4374aSIngo Molnar while (n) { 976a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 977a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 978a5f4374aSIngo Molnar 979a5f4374aSIngo Molnar if (uprobe->inode == inode) 980a5f4374aSIngo Molnar close_node = n; 981a5f4374aSIngo Molnar 982a5f4374aSIngo Molnar if (!match) 983a5f4374aSIngo Molnar return close_node; 984a5f4374aSIngo Molnar 985a5f4374aSIngo Molnar if (match < 0) 986a5f4374aSIngo Molnar n = n->rb_left; 987a5f4374aSIngo Molnar else 988a5f4374aSIngo Molnar n = n->rb_right; 989a5f4374aSIngo Molnar } 990a5f4374aSIngo Molnar 991a5f4374aSIngo Molnar return close_node; 992a5f4374aSIngo Molnar } 993a5f4374aSIngo Molnar 994a5f4374aSIngo Molnar /* 995a5f4374aSIngo Molnar * For a given inode, build a list of probes that need to be inserted. 996a5f4374aSIngo Molnar */ 997a5f4374aSIngo Molnar static void build_probe_list(struct inode *inode, struct list_head *head) 998a5f4374aSIngo Molnar { 999a5f4374aSIngo Molnar struct uprobe *uprobe; 1000a5f4374aSIngo Molnar unsigned long flags; 1001a5f4374aSIngo Molnar struct rb_node *n; 1002a5f4374aSIngo Molnar 1003a5f4374aSIngo Molnar spin_lock_irqsave(&uprobes_treelock, flags); 1004a5f4374aSIngo Molnar 1005a5f4374aSIngo Molnar n = find_least_offset_node(inode); 1006a5f4374aSIngo Molnar 1007a5f4374aSIngo Molnar for (; n; n = rb_next(n)) { 1008a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 1009a5f4374aSIngo Molnar if (uprobe->inode != inode) 1010a5f4374aSIngo Molnar break; 1011a5f4374aSIngo Molnar 1012a5f4374aSIngo Molnar list_add(&uprobe->pending_list, head); 1013a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 1014a5f4374aSIngo Molnar } 1015a5f4374aSIngo Molnar 1016a5f4374aSIngo Molnar spin_unlock_irqrestore(&uprobes_treelock, flags); 1017a5f4374aSIngo Molnar } 1018a5f4374aSIngo Molnar 1019a5f4374aSIngo Molnar /* 1020a5f4374aSIngo Molnar * Called from mmap_region. 1021a5f4374aSIngo Molnar * called with mm->mmap_sem acquired. 1022a5f4374aSIngo Molnar * 1023a5f4374aSIngo Molnar * Return -ve no if we fail to insert probes and we cannot 1024a5f4374aSIngo Molnar * bail-out. 1025a5f4374aSIngo Molnar * Return 0 otherwise. i.e: 1026a5f4374aSIngo Molnar * 1027a5f4374aSIngo Molnar * - successful insertion of probes 1028a5f4374aSIngo Molnar * - (or) no possible probes to be inserted. 1029a5f4374aSIngo Molnar * - (or) insertion of probes failed but we can bail-out. 1030a5f4374aSIngo Molnar */ 1031a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1032a5f4374aSIngo Molnar { 1033a5f4374aSIngo Molnar struct list_head tmp_list; 1034449d0d7cSOleg Nesterov struct uprobe *uprobe; 1035a5f4374aSIngo Molnar struct inode *inode; 1036682968e0SSrikar Dronamraju int ret, count; 1037a5f4374aSIngo Molnar 1038a5f4374aSIngo Molnar if (!atomic_read(&uprobe_events) || !valid_vma(vma, true)) 1039a5f4374aSIngo Molnar return 0; 1040a5f4374aSIngo Molnar 1041a5f4374aSIngo Molnar inode = vma->vm_file->f_mapping->host; 1042a5f4374aSIngo Molnar if (!inode) 1043a5f4374aSIngo Molnar return 0; 1044a5f4374aSIngo Molnar 1045a5f4374aSIngo Molnar INIT_LIST_HEAD(&tmp_list); 1046a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1047a5f4374aSIngo Molnar build_probe_list(inode, &tmp_list); 1048a5f4374aSIngo Molnar 1049a5f4374aSIngo Molnar ret = 0; 1050682968e0SSrikar Dronamraju count = 0; 1051a5f4374aSIngo Molnar 1052449d0d7cSOleg Nesterov list_for_each_entry(uprobe, &tmp_list, pending_list) { 1053a5f4374aSIngo Molnar if (!ret) { 1054816c03fbSOleg Nesterov loff_t vaddr = vma_address(vma, uprobe->offset); 1055682968e0SSrikar Dronamraju 1056682968e0SSrikar Dronamraju if (vaddr < vma->vm_start || vaddr >= vma->vm_end) { 1057682968e0SSrikar Dronamraju put_uprobe(uprobe); 1058682968e0SSrikar Dronamraju continue; 1059a5f4374aSIngo Molnar } 1060682968e0SSrikar Dronamraju 1061682968e0SSrikar Dronamraju ret = install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1062c5784de2SPeter Zijlstra /* 1063c5784de2SPeter Zijlstra * We can race against uprobe_register(), see the 1064c5784de2SPeter Zijlstra * comment near uprobe_hash(). 1065c5784de2SPeter Zijlstra */ 1066682968e0SSrikar Dronamraju if (ret == -EEXIST) { 1067682968e0SSrikar Dronamraju ret = 0; 1068682968e0SSrikar Dronamraju 1069682968e0SSrikar Dronamraju if (!is_swbp_at_addr(vma->vm_mm, vaddr)) 1070682968e0SSrikar Dronamraju continue; 1071682968e0SSrikar Dronamraju 1072682968e0SSrikar Dronamraju /* 1073682968e0SSrikar Dronamraju * Unable to insert a breakpoint, but 1074682968e0SSrikar Dronamraju * breakpoint lies underneath. Increment the 1075682968e0SSrikar Dronamraju * probe count. 1076682968e0SSrikar Dronamraju */ 1077682968e0SSrikar Dronamraju atomic_inc(&vma->vm_mm->uprobes_state.count); 1078682968e0SSrikar Dronamraju } 1079682968e0SSrikar Dronamraju 1080682968e0SSrikar Dronamraju if (!ret) 1081682968e0SSrikar Dronamraju count++; 1082a5f4374aSIngo Molnar } 1083a5f4374aSIngo Molnar put_uprobe(uprobe); 1084a5f4374aSIngo Molnar } 1085a5f4374aSIngo Molnar 1086a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1087a5f4374aSIngo Molnar 1088682968e0SSrikar Dronamraju if (ret) 1089682968e0SSrikar Dronamraju atomic_sub(count, &vma->vm_mm->uprobes_state.count); 1090682968e0SSrikar Dronamraju 1091a5f4374aSIngo Molnar return ret; 1092a5f4374aSIngo Molnar } 1093a5f4374aSIngo Molnar 1094682968e0SSrikar Dronamraju /* 1095682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1096682968e0SSrikar Dronamraju */ 1097cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1098682968e0SSrikar Dronamraju { 1099682968e0SSrikar Dronamraju struct list_head tmp_list; 1100449d0d7cSOleg Nesterov struct uprobe *uprobe; 1101682968e0SSrikar Dronamraju struct inode *inode; 1102682968e0SSrikar Dronamraju 1103682968e0SSrikar Dronamraju if (!atomic_read(&uprobe_events) || !valid_vma(vma, false)) 1104682968e0SSrikar Dronamraju return; 1105682968e0SSrikar Dronamraju 1106682968e0SSrikar Dronamraju if (!atomic_read(&vma->vm_mm->uprobes_state.count)) 1107682968e0SSrikar Dronamraju return; 1108682968e0SSrikar Dronamraju 1109682968e0SSrikar Dronamraju inode = vma->vm_file->f_mapping->host; 1110682968e0SSrikar Dronamraju if (!inode) 1111682968e0SSrikar Dronamraju return; 1112682968e0SSrikar Dronamraju 1113682968e0SSrikar Dronamraju INIT_LIST_HEAD(&tmp_list); 1114682968e0SSrikar Dronamraju mutex_lock(uprobes_mmap_hash(inode)); 1115682968e0SSrikar Dronamraju build_probe_list(inode, &tmp_list); 1116682968e0SSrikar Dronamraju 1117449d0d7cSOleg Nesterov list_for_each_entry(uprobe, &tmp_list, pending_list) { 1118816c03fbSOleg Nesterov loff_t vaddr = vma_address(vma, uprobe->offset); 1119682968e0SSrikar Dronamraju 1120cbc91f71SSrikar Dronamraju if (vaddr >= start && vaddr < end) { 1121682968e0SSrikar Dronamraju /* 1122682968e0SSrikar Dronamraju * An unregister could have removed the probe before 1123682968e0SSrikar Dronamraju * unmap. So check before we decrement the count. 1124682968e0SSrikar Dronamraju */ 1125682968e0SSrikar Dronamraju if (is_swbp_at_addr(vma->vm_mm, vaddr) == 1) 1126682968e0SSrikar Dronamraju atomic_dec(&vma->vm_mm->uprobes_state.count); 1127682968e0SSrikar Dronamraju } 1128682968e0SSrikar Dronamraju put_uprobe(uprobe); 1129682968e0SSrikar Dronamraju } 1130682968e0SSrikar Dronamraju mutex_unlock(uprobes_mmap_hash(inode)); 1131682968e0SSrikar Dronamraju } 1132682968e0SSrikar Dronamraju 1133d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 1134d4b3b638SSrikar Dronamraju static int xol_add_vma(struct xol_area *area) 1135d4b3b638SSrikar Dronamraju { 1136d4b3b638SSrikar Dronamraju struct mm_struct *mm; 1137d4b3b638SSrikar Dronamraju int ret; 1138d4b3b638SSrikar Dronamraju 1139d4b3b638SSrikar Dronamraju area->page = alloc_page(GFP_HIGHUSER); 1140d4b3b638SSrikar Dronamraju if (!area->page) 1141d4b3b638SSrikar Dronamraju return -ENOMEM; 1142d4b3b638SSrikar Dronamraju 1143d4b3b638SSrikar Dronamraju ret = -EALREADY; 1144d4b3b638SSrikar Dronamraju mm = current->mm; 1145d4b3b638SSrikar Dronamraju 1146d4b3b638SSrikar Dronamraju down_write(&mm->mmap_sem); 1147d4b3b638SSrikar Dronamraju if (mm->uprobes_state.xol_area) 1148d4b3b638SSrikar Dronamraju goto fail; 1149d4b3b638SSrikar Dronamraju 1150d4b3b638SSrikar Dronamraju ret = -ENOMEM; 1151d4b3b638SSrikar Dronamraju 1152d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1153d4b3b638SSrikar Dronamraju area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); 1154d4b3b638SSrikar Dronamraju if (area->vaddr & ~PAGE_MASK) { 1155d4b3b638SSrikar Dronamraju ret = area->vaddr; 1156d4b3b638SSrikar Dronamraju goto fail; 1157d4b3b638SSrikar Dronamraju } 1158d4b3b638SSrikar Dronamraju 1159d4b3b638SSrikar Dronamraju ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1160d4b3b638SSrikar Dronamraju VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); 1161d4b3b638SSrikar Dronamraju if (ret) 1162d4b3b638SSrikar Dronamraju goto fail; 1163d4b3b638SSrikar Dronamraju 1164d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1165d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1166d4b3b638SSrikar Dronamraju ret = 0; 1167d4b3b638SSrikar Dronamraju 1168d4b3b638SSrikar Dronamraju fail: 1169d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1170d4b3b638SSrikar Dronamraju if (ret) 1171d4b3b638SSrikar Dronamraju __free_page(area->page); 1172d4b3b638SSrikar Dronamraju 1173d4b3b638SSrikar Dronamraju return ret; 1174d4b3b638SSrikar Dronamraju } 1175d4b3b638SSrikar Dronamraju 1176d4b3b638SSrikar Dronamraju static struct xol_area *get_xol_area(struct mm_struct *mm) 1177d4b3b638SSrikar Dronamraju { 1178d4b3b638SSrikar Dronamraju struct xol_area *area; 1179d4b3b638SSrikar Dronamraju 1180d4b3b638SSrikar Dronamraju area = mm->uprobes_state.xol_area; 1181d4b3b638SSrikar Dronamraju smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 1182d4b3b638SSrikar Dronamraju 1183d4b3b638SSrikar Dronamraju return area; 1184d4b3b638SSrikar Dronamraju } 1185d4b3b638SSrikar Dronamraju 1186d4b3b638SSrikar Dronamraju /* 1187d4b3b638SSrikar Dronamraju * xol_alloc_area - Allocate process's xol_area. 1188d4b3b638SSrikar Dronamraju * This area will be used for storing instructions for execution out of 1189d4b3b638SSrikar Dronamraju * line. 1190d4b3b638SSrikar Dronamraju * 1191d4b3b638SSrikar Dronamraju * Returns the allocated area or NULL. 1192d4b3b638SSrikar Dronamraju */ 1193d4b3b638SSrikar Dronamraju static struct xol_area *xol_alloc_area(void) 1194d4b3b638SSrikar Dronamraju { 1195d4b3b638SSrikar Dronamraju struct xol_area *area; 1196d4b3b638SSrikar Dronamraju 1197d4b3b638SSrikar Dronamraju area = kzalloc(sizeof(*area), GFP_KERNEL); 1198d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1199d4b3b638SSrikar Dronamraju return NULL; 1200d4b3b638SSrikar Dronamraju 1201d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1202d4b3b638SSrikar Dronamraju 1203d4b3b638SSrikar Dronamraju if (!area->bitmap) 1204d4b3b638SSrikar Dronamraju goto fail; 1205d4b3b638SSrikar Dronamraju 1206d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 1207d4b3b638SSrikar Dronamraju if (!xol_add_vma(area)) 1208d4b3b638SSrikar Dronamraju return area; 1209d4b3b638SSrikar Dronamraju 1210d4b3b638SSrikar Dronamraju fail: 1211d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1212d4b3b638SSrikar Dronamraju kfree(area); 1213d4b3b638SSrikar Dronamraju 1214d4b3b638SSrikar Dronamraju return get_xol_area(current->mm); 1215d4b3b638SSrikar Dronamraju } 1216d4b3b638SSrikar Dronamraju 1217d4b3b638SSrikar Dronamraju /* 1218d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1219d4b3b638SSrikar Dronamraju */ 1220d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1221d4b3b638SSrikar Dronamraju { 1222d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1223d4b3b638SSrikar Dronamraju 1224d4b3b638SSrikar Dronamraju if (!area) 1225d4b3b638SSrikar Dronamraju return; 1226d4b3b638SSrikar Dronamraju 1227d4b3b638SSrikar Dronamraju put_page(area->page); 1228d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1229d4b3b638SSrikar Dronamraju kfree(area); 1230d4b3b638SSrikar Dronamraju } 1231d4b3b638SSrikar Dronamraju 1232d4b3b638SSrikar Dronamraju /* 1233d4b3b638SSrikar Dronamraju * uprobe_reset_state - Free the area allocated for slots. 1234d4b3b638SSrikar Dronamraju */ 1235d4b3b638SSrikar Dronamraju void uprobe_reset_state(struct mm_struct *mm) 1236d4b3b638SSrikar Dronamraju { 1237d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = NULL; 1238682968e0SSrikar Dronamraju atomic_set(&mm->uprobes_state.count, 0); 1239d4b3b638SSrikar Dronamraju } 1240d4b3b638SSrikar Dronamraju 1241d4b3b638SSrikar Dronamraju /* 1242d4b3b638SSrikar Dronamraju * - search for a free slot. 1243d4b3b638SSrikar Dronamraju */ 1244d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1245d4b3b638SSrikar Dronamraju { 1246d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1247d4b3b638SSrikar Dronamraju int slot_nr; 1248d4b3b638SSrikar Dronamraju 1249d4b3b638SSrikar Dronamraju do { 1250d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1251d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1252d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1253d4b3b638SSrikar Dronamraju break; 1254d4b3b638SSrikar Dronamraju 1255d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1256d4b3b638SSrikar Dronamraju continue; 1257d4b3b638SSrikar Dronamraju } 1258d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1259d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1260d4b3b638SSrikar Dronamraju 1261d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1262d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1263d4b3b638SSrikar Dronamraju 1264d4b3b638SSrikar Dronamraju return slot_addr; 1265d4b3b638SSrikar Dronamraju } 1266d4b3b638SSrikar Dronamraju 1267d4b3b638SSrikar Dronamraju /* 1268d4b3b638SSrikar Dronamraju * xol_get_insn_slot - If was not allocated a slot, then 1269d4b3b638SSrikar Dronamraju * allocate a slot. 1270d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1271d4b3b638SSrikar Dronamraju */ 1272d4b3b638SSrikar Dronamraju static unsigned long xol_get_insn_slot(struct uprobe *uprobe, unsigned long slot_addr) 1273d4b3b638SSrikar Dronamraju { 1274d4b3b638SSrikar Dronamraju struct xol_area *area; 1275d4b3b638SSrikar Dronamraju unsigned long offset; 1276d4b3b638SSrikar Dronamraju void *vaddr; 1277d4b3b638SSrikar Dronamraju 1278d4b3b638SSrikar Dronamraju area = get_xol_area(current->mm); 1279d4b3b638SSrikar Dronamraju if (!area) { 1280d4b3b638SSrikar Dronamraju area = xol_alloc_area(); 1281d4b3b638SSrikar Dronamraju if (!area) 1282d4b3b638SSrikar Dronamraju return 0; 1283d4b3b638SSrikar Dronamraju } 1284d4b3b638SSrikar Dronamraju current->utask->xol_vaddr = xol_take_insn_slot(area); 1285d4b3b638SSrikar Dronamraju 1286d4b3b638SSrikar Dronamraju /* 1287d4b3b638SSrikar Dronamraju * Initialize the slot if xol_vaddr points to valid 1288d4b3b638SSrikar Dronamraju * instruction slot. 1289d4b3b638SSrikar Dronamraju */ 1290d4b3b638SSrikar Dronamraju if (unlikely(!current->utask->xol_vaddr)) 1291d4b3b638SSrikar Dronamraju return 0; 1292d4b3b638SSrikar Dronamraju 1293d4b3b638SSrikar Dronamraju current->utask->vaddr = slot_addr; 1294d4b3b638SSrikar Dronamraju offset = current->utask->xol_vaddr & ~PAGE_MASK; 1295d4b3b638SSrikar Dronamraju vaddr = kmap_atomic(area->page); 1296d4b3b638SSrikar Dronamraju memcpy(vaddr + offset, uprobe->arch.insn, MAX_UINSN_BYTES); 1297d4b3b638SSrikar Dronamraju kunmap_atomic(vaddr); 1298d4b3b638SSrikar Dronamraju 1299d4b3b638SSrikar Dronamraju return current->utask->xol_vaddr; 1300d4b3b638SSrikar Dronamraju } 1301d4b3b638SSrikar Dronamraju 1302d4b3b638SSrikar Dronamraju /* 1303d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1304d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1305d4b3b638SSrikar Dronamraju * subsequent requests. 1306d4b3b638SSrikar Dronamraju */ 1307d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1308d4b3b638SSrikar Dronamraju { 1309d4b3b638SSrikar Dronamraju struct xol_area *area; 1310d4b3b638SSrikar Dronamraju unsigned long vma_end; 1311d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1312d4b3b638SSrikar Dronamraju 1313d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1314d4b3b638SSrikar Dronamraju return; 1315d4b3b638SSrikar Dronamraju 1316d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1317d4b3b638SSrikar Dronamraju 1318d4b3b638SSrikar Dronamraju if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr))) 1319d4b3b638SSrikar Dronamraju return; 1320d4b3b638SSrikar Dronamraju 1321d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1322d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1323d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1324d4b3b638SSrikar Dronamraju unsigned long offset; 1325d4b3b638SSrikar Dronamraju int slot_nr; 1326d4b3b638SSrikar Dronamraju 1327d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1328d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1329d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1330d4b3b638SSrikar Dronamraju return; 1331d4b3b638SSrikar Dronamraju 1332d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1333d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 1334d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1335d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1336d4b3b638SSrikar Dronamraju 1337d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1338d4b3b638SSrikar Dronamraju } 1339d4b3b638SSrikar Dronamraju } 1340d4b3b638SSrikar Dronamraju 13410326f5a9SSrikar Dronamraju /** 13420326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 13430326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 13440326f5a9SSrikar Dronamraju * instruction. 13450326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 13460326f5a9SSrikar Dronamraju */ 13470326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 13480326f5a9SSrikar Dronamraju { 13490326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 13500326f5a9SSrikar Dronamraju } 13510326f5a9SSrikar Dronamraju 13520326f5a9SSrikar Dronamraju /* 13530326f5a9SSrikar Dronamraju * Called with no locks held. 13540326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 13550326f5a9SSrikar Dronamraju */ 13560326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 13570326f5a9SSrikar Dronamraju { 13580326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13590326f5a9SSrikar Dronamraju 13600326f5a9SSrikar Dronamraju if (!utask) 13610326f5a9SSrikar Dronamraju return; 13620326f5a9SSrikar Dronamraju 13630326f5a9SSrikar Dronamraju if (utask->active_uprobe) 13640326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 13650326f5a9SSrikar Dronamraju 1366d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 13670326f5a9SSrikar Dronamraju kfree(utask); 13680326f5a9SSrikar Dronamraju t->utask = NULL; 13690326f5a9SSrikar Dronamraju } 13700326f5a9SSrikar Dronamraju 13710326f5a9SSrikar Dronamraju /* 13720326f5a9SSrikar Dronamraju * Called in context of a new clone/fork from copy_process. 13730326f5a9SSrikar Dronamraju */ 13740326f5a9SSrikar Dronamraju void uprobe_copy_process(struct task_struct *t) 13750326f5a9SSrikar Dronamraju { 13760326f5a9SSrikar Dronamraju t->utask = NULL; 13770326f5a9SSrikar Dronamraju } 13780326f5a9SSrikar Dronamraju 13790326f5a9SSrikar Dronamraju /* 13800326f5a9SSrikar Dronamraju * Allocate a uprobe_task object for the task. 13810326f5a9SSrikar Dronamraju * Called when the thread hits a breakpoint for the first time. 13820326f5a9SSrikar Dronamraju * 13830326f5a9SSrikar Dronamraju * Returns: 13840326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 13850326f5a9SSrikar Dronamraju * - NULL otherwise 13860326f5a9SSrikar Dronamraju */ 13870326f5a9SSrikar Dronamraju static struct uprobe_task *add_utask(void) 13880326f5a9SSrikar Dronamraju { 13890326f5a9SSrikar Dronamraju struct uprobe_task *utask; 13900326f5a9SSrikar Dronamraju 13910326f5a9SSrikar Dronamraju utask = kzalloc(sizeof *utask, GFP_KERNEL); 13920326f5a9SSrikar Dronamraju if (unlikely(!utask)) 13930326f5a9SSrikar Dronamraju return NULL; 13940326f5a9SSrikar Dronamraju 13950326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 13960326f5a9SSrikar Dronamraju current->utask = utask; 13970326f5a9SSrikar Dronamraju return utask; 13980326f5a9SSrikar Dronamraju } 13990326f5a9SSrikar Dronamraju 14000326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 14010326f5a9SSrikar Dronamraju static int 14020326f5a9SSrikar Dronamraju pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long vaddr) 14030326f5a9SSrikar Dronamraju { 1404d4b3b638SSrikar Dronamraju if (xol_get_insn_slot(uprobe, vaddr) && !arch_uprobe_pre_xol(&uprobe->arch, regs)) 1405d4b3b638SSrikar Dronamraju return 0; 1406d4b3b638SSrikar Dronamraju 14070326f5a9SSrikar Dronamraju return -EFAULT; 14080326f5a9SSrikar Dronamraju } 14090326f5a9SSrikar Dronamraju 14100326f5a9SSrikar Dronamraju /* 14110326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 14120326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 14130326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 14140326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 14150326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 14160326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 14170326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 14180326f5a9SSrikar Dronamraju */ 14190326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 14200326f5a9SSrikar Dronamraju { 14210326f5a9SSrikar Dronamraju struct task_struct *t = current; 14220326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 14230326f5a9SSrikar Dronamraju 14240326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 14250326f5a9SSrikar Dronamraju return false; 14260326f5a9SSrikar Dronamraju 14270326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 14280326f5a9SSrikar Dronamraju 14290326f5a9SSrikar Dronamraju if (signal_pending(t)) { 14300326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 14310326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 14320326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 14330326f5a9SSrikar Dronamraju 14340326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 14350326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 14360326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 14370326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); 14380326f5a9SSrikar Dronamraju } 14390326f5a9SSrikar Dronamraju } 14400326f5a9SSrikar Dronamraju 14410326f5a9SSrikar Dronamraju return true; 14420326f5a9SSrikar Dronamraju } 14430326f5a9SSrikar Dronamraju 14440326f5a9SSrikar Dronamraju /* 14450326f5a9SSrikar Dronamraju * Avoid singlestepping the original instruction if the original instruction 14460326f5a9SSrikar Dronamraju * is a NOP or can be emulated. 14470326f5a9SSrikar Dronamraju */ 14480326f5a9SSrikar Dronamraju static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) 14490326f5a9SSrikar Dronamraju { 14500326f5a9SSrikar Dronamraju if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 14510326f5a9SSrikar Dronamraju return true; 14520326f5a9SSrikar Dronamraju 14530326f5a9SSrikar Dronamraju uprobe->flags &= ~UPROBE_SKIP_SSTEP; 14540326f5a9SSrikar Dronamraju return false; 14550326f5a9SSrikar Dronamraju } 14560326f5a9SSrikar Dronamraju 1457d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 14580326f5a9SSrikar Dronamraju { 14593a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 14603a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 14610326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 14620326f5a9SSrikar Dronamraju 14630326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 14640326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 14653a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 14663a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 14670326f5a9SSrikar Dronamraju struct inode *inode; 14680326f5a9SSrikar Dronamraju loff_t offset; 14690326f5a9SSrikar Dronamraju 14700326f5a9SSrikar Dronamraju inode = vma->vm_file->f_mapping->host; 14710326f5a9SSrikar Dronamraju offset = bp_vaddr - vma->vm_start; 14720326f5a9SSrikar Dronamraju offset += (vma->vm_pgoff << PAGE_SHIFT); 14730326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 14740326f5a9SSrikar Dronamraju } 1475d790d346SOleg Nesterov 1476d790d346SOleg Nesterov if (!uprobe) 1477d790d346SOleg Nesterov *is_swbp = is_swbp_at_addr(mm, bp_vaddr); 1478d790d346SOleg Nesterov } else { 1479d790d346SOleg Nesterov *is_swbp = -EFAULT; 14803a9ea052SOleg Nesterov } 14810326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 14820326f5a9SSrikar Dronamraju 14833a9ea052SOleg Nesterov return uprobe; 14843a9ea052SOleg Nesterov } 14853a9ea052SOleg Nesterov 14863a9ea052SOleg Nesterov /* 14873a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 14883a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 14893a9ea052SOleg Nesterov */ 14903a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 14913a9ea052SOleg Nesterov { 14923a9ea052SOleg Nesterov struct uprobe_task *utask; 14933a9ea052SOleg Nesterov struct uprobe *uprobe; 14943a9ea052SOleg Nesterov unsigned long bp_vaddr; 149556bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 14963a9ea052SOleg Nesterov 14973a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 1498d790d346SOleg Nesterov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 14993a9ea052SOleg Nesterov 15000326f5a9SSrikar Dronamraju if (!uprobe) { 150156bb4cf6SOleg Nesterov if (is_swbp > 0) { 15020326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 15030326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 150456bb4cf6SOleg Nesterov } else { 150556bb4cf6SOleg Nesterov /* 150656bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 150756bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 150856bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 150956bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 151056bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 151156bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 151256bb4cf6SOleg Nesterov */ 151356bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 151456bb4cf6SOleg Nesterov } 15150326f5a9SSrikar Dronamraju return; 15160326f5a9SSrikar Dronamraju } 15170326f5a9SSrikar Dronamraju 15180326f5a9SSrikar Dronamraju utask = current->utask; 15190326f5a9SSrikar Dronamraju if (!utask) { 15200326f5a9SSrikar Dronamraju utask = add_utask(); 15210326f5a9SSrikar Dronamraju /* Cannot allocate; re-execute the instruction. */ 15220326f5a9SSrikar Dronamraju if (!utask) 15230326f5a9SSrikar Dronamraju goto cleanup_ret; 15240326f5a9SSrikar Dronamraju } 15250326f5a9SSrikar Dronamraju utask->active_uprobe = uprobe; 15260326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 15270326f5a9SSrikar Dronamraju if (uprobe->flags & UPROBE_SKIP_SSTEP && can_skip_sstep(uprobe, regs)) 15280326f5a9SSrikar Dronamraju goto cleanup_ret; 15290326f5a9SSrikar Dronamraju 15300326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP; 15310326f5a9SSrikar Dronamraju if (!pre_ssout(uprobe, regs, bp_vaddr)) { 15320326f5a9SSrikar Dronamraju user_enable_single_step(current); 15330326f5a9SSrikar Dronamraju return; 15340326f5a9SSrikar Dronamraju } 15350326f5a9SSrikar Dronamraju 15360326f5a9SSrikar Dronamraju cleanup_ret: 15370326f5a9SSrikar Dronamraju if (utask) { 15380326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15390326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 15400326f5a9SSrikar Dronamraju } 15410326f5a9SSrikar Dronamraju if (uprobe) { 15420326f5a9SSrikar Dronamraju if (!(uprobe->flags & UPROBE_SKIP_SSTEP)) 15430326f5a9SSrikar Dronamraju 15440326f5a9SSrikar Dronamraju /* 15450326f5a9SSrikar Dronamraju * cannot singlestep; cannot skip instruction; 15460326f5a9SSrikar Dronamraju * re-execute the instruction. 15470326f5a9SSrikar Dronamraju */ 15480326f5a9SSrikar Dronamraju instruction_pointer_set(regs, bp_vaddr); 15490326f5a9SSrikar Dronamraju 15500326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15510326f5a9SSrikar Dronamraju } 15520326f5a9SSrikar Dronamraju } 15530326f5a9SSrikar Dronamraju 15540326f5a9SSrikar Dronamraju /* 15550326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 15560326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 15570326f5a9SSrikar Dronamraju */ 15580326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 15590326f5a9SSrikar Dronamraju { 15600326f5a9SSrikar Dronamraju struct uprobe *uprobe; 15610326f5a9SSrikar Dronamraju 15620326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 15630326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 15640326f5a9SSrikar Dronamraju arch_uprobe_post_xol(&uprobe->arch, regs); 15650326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 15660326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 15670326f5a9SSrikar Dronamraju else 15680326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 15690326f5a9SSrikar Dronamraju 15700326f5a9SSrikar Dronamraju put_uprobe(uprobe); 15710326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 15720326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 15730326f5a9SSrikar Dronamraju user_disable_single_step(current); 1574d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 15750326f5a9SSrikar Dronamraju 15760326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 15770326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 15780326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 15790326f5a9SSrikar Dronamraju } 15800326f5a9SSrikar Dronamraju 15810326f5a9SSrikar Dronamraju /* 15820326f5a9SSrikar Dronamraju * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag. (and on 15830326f5a9SSrikar Dronamraju * subsequent probe hits on the thread sets the state to UTASK_BP_HIT) and 15840326f5a9SSrikar Dronamraju * allows the thread to return from interrupt. 15850326f5a9SSrikar Dronamraju * 15860326f5a9SSrikar Dronamraju * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag and 15870326f5a9SSrikar Dronamraju * also sets the state to UTASK_SSTEP_ACK and allows the thread to return from 15880326f5a9SSrikar Dronamraju * interrupt. 15890326f5a9SSrikar Dronamraju * 15900326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 15910326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 15920326f5a9SSrikar Dronamraju */ 15930326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 15940326f5a9SSrikar Dronamraju { 15950326f5a9SSrikar Dronamraju struct uprobe_task *utask; 15960326f5a9SSrikar Dronamraju 15970326f5a9SSrikar Dronamraju utask = current->utask; 15980326f5a9SSrikar Dronamraju if (!utask || utask->state == UTASK_BP_HIT) 15990326f5a9SSrikar Dronamraju handle_swbp(regs); 16000326f5a9SSrikar Dronamraju else 16010326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 16020326f5a9SSrikar Dronamraju } 16030326f5a9SSrikar Dronamraju 16040326f5a9SSrikar Dronamraju /* 16050326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 16060326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 16070326f5a9SSrikar Dronamraju */ 16080326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 16090326f5a9SSrikar Dronamraju { 16100326f5a9SSrikar Dronamraju struct uprobe_task *utask; 16110326f5a9SSrikar Dronamraju 1612682968e0SSrikar Dronamraju if (!current->mm || !atomic_read(¤t->mm->uprobes_state.count)) 1613682968e0SSrikar Dronamraju /* task is currently not uprobed */ 16140326f5a9SSrikar Dronamraju return 0; 16150326f5a9SSrikar Dronamraju 16160326f5a9SSrikar Dronamraju utask = current->utask; 16170326f5a9SSrikar Dronamraju if (utask) 16180326f5a9SSrikar Dronamraju utask->state = UTASK_BP_HIT; 16190326f5a9SSrikar Dronamraju 16200326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 16210326f5a9SSrikar Dronamraju 16220326f5a9SSrikar Dronamraju return 1; 16230326f5a9SSrikar Dronamraju } 16240326f5a9SSrikar Dronamraju 16250326f5a9SSrikar Dronamraju /* 16260326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 16270326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 16280326f5a9SSrikar Dronamraju */ 16290326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 16300326f5a9SSrikar Dronamraju { 16310326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 16320326f5a9SSrikar Dronamraju 16330326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 16340326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 16350326f5a9SSrikar Dronamraju return 0; 16360326f5a9SSrikar Dronamraju 16370326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 16380326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 16390326f5a9SSrikar Dronamraju return 1; 16400326f5a9SSrikar Dronamraju } 16410326f5a9SSrikar Dronamraju 16420326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 16430326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 16440326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 16450326f5a9SSrikar Dronamraju }; 16460326f5a9SSrikar Dronamraju 1647a5f4374aSIngo Molnar static int __init init_uprobes(void) 1648a5f4374aSIngo Molnar { 1649a5f4374aSIngo Molnar int i; 1650a5f4374aSIngo Molnar 1651a5f4374aSIngo Molnar for (i = 0; i < UPROBES_HASH_SZ; i++) { 1652a5f4374aSIngo Molnar mutex_init(&uprobes_mutex[i]); 1653a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 1654a5f4374aSIngo Molnar } 16550326f5a9SSrikar Dronamraju 16560326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 1657a5f4374aSIngo Molnar } 16580326f5a9SSrikar Dronamraju module_init(init_uprobes); 1659a5f4374aSIngo Molnar 1660a5f4374aSIngo Molnar static void __exit exit_uprobes(void) 1661a5f4374aSIngo Molnar { 1662a5f4374aSIngo Molnar } 1663a5f4374aSIngo Molnar module_exit(exit_uprobes); 1664