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> 30e8440c14SJosh Stone #include <linux/export.h> 31a5f4374aSIngo Molnar #include <linux/rmap.h> /* anon_vma_prepare */ 32a5f4374aSIngo Molnar #include <linux/mmu_notifier.h> /* set_pte_at_notify */ 33a5f4374aSIngo Molnar #include <linux/swap.h> /* try_to_free_swap */ 340326f5a9SSrikar Dronamraju #include <linux/ptrace.h> /* user_enable_single_step */ 350326f5a9SSrikar Dronamraju #include <linux/kdebug.h> /* notifier mechanism */ 36194f8dcbSOleg Nesterov #include "../../mm/internal.h" /* munlock_vma_page */ 3732cdba1eSOleg Nesterov #include <linux/percpu-rwsem.h> 38aa59c53fSOleg Nesterov #include <linux/task_work.h> 39a5f4374aSIngo Molnar 40a5f4374aSIngo Molnar #include <linux/uprobes.h> 41a5f4374aSIngo Molnar 42d4b3b638SSrikar Dronamraju #define UINSNS_PER_PAGE (PAGE_SIZE/UPROBE_XOL_SLOT_BYTES) 43d4b3b638SSrikar Dronamraju #define MAX_UPROBE_XOL_SLOTS UINSNS_PER_PAGE 44d4b3b638SSrikar Dronamraju 45a5f4374aSIngo Molnar static struct rb_root uprobes_tree = RB_ROOT; 46441f1eb7SOleg Nesterov /* 47441f1eb7SOleg Nesterov * allows us to skip the uprobe_mmap if there are no uprobe events active 48441f1eb7SOleg Nesterov * at this time. Probably a fine grained per inode count is better? 49441f1eb7SOleg Nesterov */ 50441f1eb7SOleg Nesterov #define no_uprobe_events() RB_EMPTY_ROOT(&uprobes_tree) 51a5f4374aSIngo Molnar 52a5f4374aSIngo Molnar static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */ 53a5f4374aSIngo Molnar 54a5f4374aSIngo Molnar #define UPROBES_HASH_SZ 13 55a5f4374aSIngo Molnar /* serialize uprobe->pending_list */ 56a5f4374aSIngo Molnar static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ]; 57a5f4374aSIngo Molnar #define uprobes_mmap_hash(v) (&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ]) 58a5f4374aSIngo Molnar 5932cdba1eSOleg Nesterov static struct percpu_rw_semaphore dup_mmap_sem; 6032cdba1eSOleg Nesterov 61cb9a19feSOleg Nesterov /* Have a copy of original instruction */ 6271434f2fSOleg Nesterov #define UPROBE_COPY_INSN 0 63cb9a19feSOleg Nesterov /* Can skip singlestep */ 64bb929284SOleg Nesterov #define UPROBE_SKIP_SSTEP 1 65cb9a19feSOleg Nesterov 663ff54efdSSrikar Dronamraju struct uprobe { 673ff54efdSSrikar Dronamraju struct rb_node rb_node; /* node in the rb tree */ 683ff54efdSSrikar Dronamraju atomic_t ref; 69e591c8d7SOleg Nesterov struct rw_semaphore register_rwsem; 703ff54efdSSrikar Dronamraju struct rw_semaphore consumer_rwsem; 713ff54efdSSrikar Dronamraju struct list_head pending_list; 723ff54efdSSrikar Dronamraju struct uprobe_consumer *consumers; 733ff54efdSSrikar Dronamraju struct inode *inode; /* Also hold a ref to inode */ 743ff54efdSSrikar Dronamraju loff_t offset; 7571434f2fSOleg Nesterov unsigned long flags; 763ff54efdSSrikar Dronamraju struct arch_uprobe arch; 773ff54efdSSrikar Dronamraju }; 783ff54efdSSrikar Dronamraju 790dfd0eb8SAnton Arapov struct return_instance { 800dfd0eb8SAnton Arapov struct uprobe *uprobe; 810dfd0eb8SAnton Arapov unsigned long func; 820dfd0eb8SAnton Arapov unsigned long orig_ret_vaddr; /* original return address */ 830dfd0eb8SAnton Arapov bool chained; /* true, if instance is nested */ 840dfd0eb8SAnton Arapov 850dfd0eb8SAnton Arapov struct return_instance *next; /* keep as stack */ 860dfd0eb8SAnton Arapov }; 870dfd0eb8SAnton Arapov 88a5f4374aSIngo Molnar /* 89a5f4374aSIngo Molnar * valid_vma: Verify if the specified vma is an executable vma 90a5f4374aSIngo Molnar * Relax restrictions while unregistering: vm_flags might have 91a5f4374aSIngo Molnar * changed after breakpoint was inserted. 92a5f4374aSIngo Molnar * - is_register: indicates if we are in register context. 93a5f4374aSIngo Molnar * - Return 1 if the specified virtual address is in an 94a5f4374aSIngo Molnar * executable vma. 95a5f4374aSIngo Molnar */ 96a5f4374aSIngo Molnar static bool valid_vma(struct vm_area_struct *vma, bool is_register) 97a5f4374aSIngo Molnar { 98e40cfce6SOleg Nesterov vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED; 99a5f4374aSIngo Molnar 100e40cfce6SOleg Nesterov if (is_register) 101e40cfce6SOleg Nesterov flags |= VM_WRITE; 102a5f4374aSIngo Molnar 103e40cfce6SOleg Nesterov return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; 104a5f4374aSIngo Molnar } 105a5f4374aSIngo Molnar 10657683f72SOleg Nesterov static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) 107a5f4374aSIngo Molnar { 10857683f72SOleg Nesterov return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); 109a5f4374aSIngo Molnar } 110a5f4374aSIngo Molnar 111cb113b47SOleg Nesterov static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) 112cb113b47SOleg Nesterov { 113cb113b47SOleg Nesterov return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); 114cb113b47SOleg Nesterov } 115cb113b47SOleg Nesterov 116a5f4374aSIngo Molnar /** 117a5f4374aSIngo Molnar * __replace_page - replace page in vma by new page. 118a5f4374aSIngo Molnar * based on replace_page in mm/ksm.c 119a5f4374aSIngo Molnar * 120a5f4374aSIngo Molnar * @vma: vma that holds the pte pointing to page 121c517ee74SOleg Nesterov * @addr: address the old @page is mapped at 122a5f4374aSIngo Molnar * @page: the cowed page we are replacing by kpage 123a5f4374aSIngo Molnar * @kpage: the modified page we replace page by 124a5f4374aSIngo Molnar * 125a5f4374aSIngo Molnar * Returns 0 on success, -EFAULT on failure. 126a5f4374aSIngo Molnar */ 127c517ee74SOleg Nesterov static int __replace_page(struct vm_area_struct *vma, unsigned long addr, 128c517ee74SOleg Nesterov struct page *page, struct page *kpage) 129a5f4374aSIngo Molnar { 130a5f4374aSIngo Molnar struct mm_struct *mm = vma->vm_mm; 1315323ce71SOleg Nesterov spinlock_t *ptl; 1325323ce71SOleg Nesterov pte_t *ptep; 1339f92448cSOleg Nesterov int err; 1346bdb913fSHaggai Eran /* For mmu_notifiers */ 1356bdb913fSHaggai Eran const unsigned long mmun_start = addr; 1366bdb913fSHaggai Eran const unsigned long mmun_end = addr + PAGE_SIZE; 137a5f4374aSIngo Molnar 138194f8dcbSOleg Nesterov /* For try_to_free_swap() and munlock_vma_page() below */ 1399f92448cSOleg Nesterov lock_page(page); 1409f92448cSOleg Nesterov 1416bdb913fSHaggai Eran mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 1429f92448cSOleg Nesterov err = -EAGAIN; 1435323ce71SOleg Nesterov ptep = page_check_address(page, mm, addr, &ptl, 0); 144a5f4374aSIngo Molnar if (!ptep) 1459f92448cSOleg Nesterov goto unlock; 146a5f4374aSIngo Molnar 147a5f4374aSIngo Molnar get_page(kpage); 148a5f4374aSIngo Molnar page_add_new_anon_rmap(kpage, vma, addr); 149a5f4374aSIngo Molnar 1507396fa81SSrikar Dronamraju if (!PageAnon(page)) { 1517396fa81SSrikar Dronamraju dec_mm_counter(mm, MM_FILEPAGES); 1527396fa81SSrikar Dronamraju inc_mm_counter(mm, MM_ANONPAGES); 1537396fa81SSrikar Dronamraju } 1547396fa81SSrikar Dronamraju 155a5f4374aSIngo Molnar flush_cache_page(vma, addr, pte_pfn(*ptep)); 156a5f4374aSIngo Molnar ptep_clear_flush(vma, addr, ptep); 157a5f4374aSIngo Molnar set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot)); 158a5f4374aSIngo Molnar 159a5f4374aSIngo Molnar page_remove_rmap(page); 160a5f4374aSIngo Molnar if (!page_mapped(page)) 161a5f4374aSIngo Molnar try_to_free_swap(page); 162a5f4374aSIngo Molnar pte_unmap_unlock(ptep, ptl); 163a5f4374aSIngo Molnar 164194f8dcbSOleg Nesterov if (vma->vm_flags & VM_LOCKED) 165194f8dcbSOleg Nesterov munlock_vma_page(page); 166194f8dcbSOleg Nesterov put_page(page); 167194f8dcbSOleg Nesterov 1689f92448cSOleg Nesterov err = 0; 1699f92448cSOleg Nesterov unlock: 1706bdb913fSHaggai Eran mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 1719f92448cSOleg Nesterov unlock_page(page); 1729f92448cSOleg Nesterov return err; 173a5f4374aSIngo Molnar } 174a5f4374aSIngo Molnar 175a5f4374aSIngo Molnar /** 1765cb4ac3aSSrikar Dronamraju * is_swbp_insn - check if instruction is breakpoint instruction. 177a5f4374aSIngo Molnar * @insn: instruction to be checked. 1785cb4ac3aSSrikar Dronamraju * Default implementation of is_swbp_insn 179a5f4374aSIngo Molnar * Returns true if @insn is a breakpoint instruction. 180a5f4374aSIngo Molnar */ 1815cb4ac3aSSrikar Dronamraju bool __weak is_swbp_insn(uprobe_opcode_t *insn) 182a5f4374aSIngo Molnar { 1835cb4ac3aSSrikar Dronamraju return *insn == UPROBE_SWBP_INSN; 184a5f4374aSIngo Molnar } 185a5f4374aSIngo Molnar 1860908ad6eSAnanth N Mavinakayanahalli /** 1870908ad6eSAnanth N Mavinakayanahalli * is_trap_insn - check if instruction is breakpoint instruction. 1880908ad6eSAnanth N Mavinakayanahalli * @insn: instruction to be checked. 1890908ad6eSAnanth N Mavinakayanahalli * Default implementation of is_trap_insn 1900908ad6eSAnanth N Mavinakayanahalli * Returns true if @insn is a breakpoint instruction. 1910908ad6eSAnanth N Mavinakayanahalli * 1920908ad6eSAnanth N Mavinakayanahalli * This function is needed for the case where an architecture has multiple 1930908ad6eSAnanth N Mavinakayanahalli * trap instructions (like powerpc). 1940908ad6eSAnanth N Mavinakayanahalli */ 1950908ad6eSAnanth N Mavinakayanahalli bool __weak is_trap_insn(uprobe_opcode_t *insn) 1960908ad6eSAnanth N Mavinakayanahalli { 1970908ad6eSAnanth N Mavinakayanahalli return is_swbp_insn(insn); 1980908ad6eSAnanth N Mavinakayanahalli } 1990908ad6eSAnanth N Mavinakayanahalli 200ab0d805cSOleg Nesterov static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) 201cceb55aaSOleg Nesterov { 202cceb55aaSOleg Nesterov void *kaddr = kmap_atomic(page); 203ab0d805cSOleg Nesterov memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); 204cceb55aaSOleg Nesterov kunmap_atomic(kaddr); 205cceb55aaSOleg Nesterov } 206cceb55aaSOleg Nesterov 2075669cceeSOleg Nesterov static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) 2085669cceeSOleg Nesterov { 2095669cceeSOleg Nesterov void *kaddr = kmap_atomic(page); 2105669cceeSOleg Nesterov memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); 2115669cceeSOleg Nesterov kunmap_atomic(kaddr); 2125669cceeSOleg Nesterov } 2135669cceeSOleg Nesterov 214ed6f6a50SOleg Nesterov static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) 215ed6f6a50SOleg Nesterov { 216ed6f6a50SOleg Nesterov uprobe_opcode_t old_opcode; 217ed6f6a50SOleg Nesterov bool is_swbp; 218ed6f6a50SOleg Nesterov 2190908ad6eSAnanth N Mavinakayanahalli /* 2200908ad6eSAnanth N Mavinakayanahalli * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. 2210908ad6eSAnanth N Mavinakayanahalli * We do not check if it is any other 'trap variant' which could 2220908ad6eSAnanth N Mavinakayanahalli * be conditional trap instruction such as the one powerpc supports. 2230908ad6eSAnanth N Mavinakayanahalli * 2240908ad6eSAnanth N Mavinakayanahalli * The logic is that we do not care if the underlying instruction 2250908ad6eSAnanth N Mavinakayanahalli * is a trap variant; uprobes always wins over any other (gdb) 2260908ad6eSAnanth N Mavinakayanahalli * breakpoint. 2270908ad6eSAnanth N Mavinakayanahalli */ 228ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); 229ed6f6a50SOleg Nesterov is_swbp = is_swbp_insn(&old_opcode); 230ed6f6a50SOleg Nesterov 231ed6f6a50SOleg Nesterov if (is_swbp_insn(new_opcode)) { 232ed6f6a50SOleg Nesterov if (is_swbp) /* register: already installed? */ 233ed6f6a50SOleg Nesterov return 0; 234ed6f6a50SOleg Nesterov } else { 235ed6f6a50SOleg Nesterov if (!is_swbp) /* unregister: was it changed by us? */ 236076a365bSOleg Nesterov return 0; 237ed6f6a50SOleg Nesterov } 238ed6f6a50SOleg Nesterov 239ed6f6a50SOleg Nesterov return 1; 240ed6f6a50SOleg Nesterov } 241ed6f6a50SOleg Nesterov 242a5f4374aSIngo Molnar /* 243a5f4374aSIngo Molnar * NOTE: 244a5f4374aSIngo Molnar * Expect the breakpoint instruction to be the smallest size instruction for 245a5f4374aSIngo Molnar * the architecture. If an arch has variable length instruction and the 246a5f4374aSIngo Molnar * breakpoint instruction is not of the smallest length instruction 2470908ad6eSAnanth N Mavinakayanahalli * supported by that architecture then we need to modify is_trap_at_addr and 248a5f4374aSIngo Molnar * write_opcode accordingly. This would never be a problem for archs that 249a5f4374aSIngo Molnar * have fixed length instructions. 250a5f4374aSIngo Molnar */ 251a5f4374aSIngo Molnar 252a5f4374aSIngo Molnar /* 253a5f4374aSIngo Molnar * write_opcode - write the opcode at a given virtual address. 254a5f4374aSIngo Molnar * @mm: the probed process address space. 255a5f4374aSIngo Molnar * @vaddr: the virtual address to store the opcode. 256a5f4374aSIngo Molnar * @opcode: opcode to be written at @vaddr. 257a5f4374aSIngo Molnar * 258a5f4374aSIngo Molnar * Called with mm->mmap_sem held (for read and with a reference to 259a5f4374aSIngo Molnar * mm). 260a5f4374aSIngo Molnar * 261a5f4374aSIngo Molnar * For mm @mm, write the opcode at @vaddr. 262a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 263a5f4374aSIngo Molnar */ 264cceb55aaSOleg Nesterov static int write_opcode(struct mm_struct *mm, unsigned long vaddr, 265cceb55aaSOleg Nesterov uprobe_opcode_t opcode) 266a5f4374aSIngo Molnar { 267a5f4374aSIngo Molnar struct page *old_page, *new_page; 268a5f4374aSIngo Molnar struct vm_area_struct *vma; 269a5f4374aSIngo Molnar int ret; 270f403072cSOleg Nesterov 2715323ce71SOleg Nesterov retry: 272a5f4374aSIngo Molnar /* Read the page with vaddr into memory */ 27375ed82eaSOleg Nesterov ret = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &old_page, &vma); 274a5f4374aSIngo Molnar if (ret <= 0) 275a5f4374aSIngo Molnar return ret; 276a5f4374aSIngo Molnar 277ed6f6a50SOleg Nesterov ret = verify_opcode(old_page, vaddr, &opcode); 278ed6f6a50SOleg Nesterov if (ret <= 0) 279ed6f6a50SOleg Nesterov goto put_old; 280ed6f6a50SOleg Nesterov 281a5f4374aSIngo Molnar ret = -ENOMEM; 282a5f4374aSIngo Molnar new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); 283a5f4374aSIngo Molnar if (!new_page) 2849f92448cSOleg Nesterov goto put_old; 285a5f4374aSIngo Molnar 286a5f4374aSIngo Molnar __SetPageUptodate(new_page); 287a5f4374aSIngo Molnar 2883f47107cSOleg Nesterov copy_highpage(new_page, old_page); 2893f47107cSOleg Nesterov copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 290a5f4374aSIngo Molnar 291a5f4374aSIngo Molnar ret = anon_vma_prepare(vma); 292a5f4374aSIngo Molnar if (ret) 2939f92448cSOleg Nesterov goto put_new; 294a5f4374aSIngo Molnar 295c517ee74SOleg Nesterov ret = __replace_page(vma, vaddr, old_page, new_page); 296a5f4374aSIngo Molnar 2979f92448cSOleg Nesterov put_new: 298a5f4374aSIngo Molnar page_cache_release(new_page); 2999f92448cSOleg Nesterov put_old: 300a5f4374aSIngo Molnar put_page(old_page); 301a5f4374aSIngo Molnar 3025323ce71SOleg Nesterov if (unlikely(ret == -EAGAIN)) 3035323ce71SOleg Nesterov goto retry; 304a5f4374aSIngo Molnar return ret; 305a5f4374aSIngo Molnar } 306a5f4374aSIngo Molnar 307a5f4374aSIngo Molnar /** 3085cb4ac3aSSrikar Dronamraju * set_swbp - store breakpoint at a given address. 309e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 310a5f4374aSIngo Molnar * @mm: the probed process address space. 311a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 312a5f4374aSIngo Molnar * 313a5f4374aSIngo Molnar * For mm @mm, store the breakpoint instruction at @vaddr. 314a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 315a5f4374aSIngo Molnar */ 3165cb4ac3aSSrikar Dronamraju int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 317a5f4374aSIngo Molnar { 318cceb55aaSOleg Nesterov return write_opcode(mm, vaddr, UPROBE_SWBP_INSN); 319a5f4374aSIngo Molnar } 320a5f4374aSIngo Molnar 321a5f4374aSIngo Molnar /** 322a5f4374aSIngo Molnar * set_orig_insn - Restore the original instruction. 323a5f4374aSIngo Molnar * @mm: the probed process address space. 324e3343e6aSSrikar Dronamraju * @auprobe: arch specific probepoint information. 325a5f4374aSIngo Molnar * @vaddr: the virtual address to insert the opcode. 326a5f4374aSIngo Molnar * 327a5f4374aSIngo Molnar * For mm @mm, restore the original opcode (opcode) at @vaddr. 328a5f4374aSIngo Molnar * Return 0 (success) or a negative errno. 329a5f4374aSIngo Molnar */ 330a5f4374aSIngo Molnar int __weak 331ded86e7cSOleg Nesterov set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) 332a5f4374aSIngo Molnar { 333cceb55aaSOleg Nesterov return write_opcode(mm, vaddr, *(uprobe_opcode_t *)auprobe->insn); 334a5f4374aSIngo Molnar } 335a5f4374aSIngo Molnar 336a5f4374aSIngo Molnar static int match_uprobe(struct uprobe *l, struct uprobe *r) 337a5f4374aSIngo Molnar { 338a5f4374aSIngo Molnar if (l->inode < r->inode) 339a5f4374aSIngo Molnar return -1; 340a5f4374aSIngo Molnar 341a5f4374aSIngo Molnar if (l->inode > r->inode) 342a5f4374aSIngo Molnar return 1; 343a5f4374aSIngo Molnar 344a5f4374aSIngo Molnar if (l->offset < r->offset) 345a5f4374aSIngo Molnar return -1; 346a5f4374aSIngo Molnar 347a5f4374aSIngo Molnar if (l->offset > r->offset) 348a5f4374aSIngo Molnar return 1; 349a5f4374aSIngo Molnar 350a5f4374aSIngo Molnar return 0; 351a5f4374aSIngo Molnar } 352a5f4374aSIngo Molnar 353a5f4374aSIngo Molnar static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) 354a5f4374aSIngo Molnar { 355a5f4374aSIngo Molnar struct uprobe u = { .inode = inode, .offset = offset }; 356a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 357a5f4374aSIngo Molnar struct uprobe *uprobe; 358a5f4374aSIngo Molnar int match; 359a5f4374aSIngo Molnar 360a5f4374aSIngo Molnar while (n) { 361a5f4374aSIngo Molnar uprobe = rb_entry(n, struct uprobe, rb_node); 362a5f4374aSIngo Molnar match = match_uprobe(&u, uprobe); 363a5f4374aSIngo Molnar if (!match) { 364a5f4374aSIngo Molnar atomic_inc(&uprobe->ref); 365a5f4374aSIngo Molnar return uprobe; 366a5f4374aSIngo Molnar } 367a5f4374aSIngo Molnar 368a5f4374aSIngo Molnar if (match < 0) 369a5f4374aSIngo Molnar n = n->rb_left; 370a5f4374aSIngo Molnar else 371a5f4374aSIngo Molnar n = n->rb_right; 372a5f4374aSIngo Molnar } 373a5f4374aSIngo Molnar return NULL; 374a5f4374aSIngo Molnar } 375a5f4374aSIngo Molnar 376a5f4374aSIngo Molnar /* 377a5f4374aSIngo Molnar * Find a uprobe corresponding to a given inode:offset 378a5f4374aSIngo Molnar * Acquires uprobes_treelock 379a5f4374aSIngo Molnar */ 380a5f4374aSIngo Molnar static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) 381a5f4374aSIngo Molnar { 382a5f4374aSIngo Molnar struct uprobe *uprobe; 383a5f4374aSIngo Molnar 3846f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 385a5f4374aSIngo Molnar uprobe = __find_uprobe(inode, offset); 3866f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 387a5f4374aSIngo Molnar 388a5f4374aSIngo Molnar return uprobe; 389a5f4374aSIngo Molnar } 390a5f4374aSIngo Molnar 391a5f4374aSIngo Molnar static struct uprobe *__insert_uprobe(struct uprobe *uprobe) 392a5f4374aSIngo Molnar { 393a5f4374aSIngo Molnar struct rb_node **p = &uprobes_tree.rb_node; 394a5f4374aSIngo Molnar struct rb_node *parent = NULL; 395a5f4374aSIngo Molnar struct uprobe *u; 396a5f4374aSIngo Molnar int match; 397a5f4374aSIngo Molnar 398a5f4374aSIngo Molnar while (*p) { 399a5f4374aSIngo Molnar parent = *p; 400a5f4374aSIngo Molnar u = rb_entry(parent, struct uprobe, rb_node); 401a5f4374aSIngo Molnar match = match_uprobe(uprobe, u); 402a5f4374aSIngo Molnar if (!match) { 403a5f4374aSIngo Molnar atomic_inc(&u->ref); 404a5f4374aSIngo Molnar return u; 405a5f4374aSIngo Molnar } 406a5f4374aSIngo Molnar 407a5f4374aSIngo Molnar if (match < 0) 408a5f4374aSIngo Molnar p = &parent->rb_left; 409a5f4374aSIngo Molnar else 410a5f4374aSIngo Molnar p = &parent->rb_right; 411a5f4374aSIngo Molnar 412a5f4374aSIngo Molnar } 413a5f4374aSIngo Molnar 414a5f4374aSIngo Molnar u = NULL; 415a5f4374aSIngo Molnar rb_link_node(&uprobe->rb_node, parent, p); 416a5f4374aSIngo Molnar rb_insert_color(&uprobe->rb_node, &uprobes_tree); 417a5f4374aSIngo Molnar /* get access + creation ref */ 418a5f4374aSIngo Molnar atomic_set(&uprobe->ref, 2); 419a5f4374aSIngo Molnar 420a5f4374aSIngo Molnar return u; 421a5f4374aSIngo Molnar } 422a5f4374aSIngo Molnar 423a5f4374aSIngo Molnar /* 424a5f4374aSIngo Molnar * Acquire uprobes_treelock. 425a5f4374aSIngo Molnar * Matching uprobe already exists in rbtree; 426a5f4374aSIngo Molnar * increment (access refcount) and return the matching uprobe. 427a5f4374aSIngo Molnar * 428a5f4374aSIngo Molnar * No matching uprobe; insert the uprobe in rb_tree; 429a5f4374aSIngo Molnar * get a double refcount (access + creation) and return NULL. 430a5f4374aSIngo Molnar */ 431a5f4374aSIngo Molnar static struct uprobe *insert_uprobe(struct uprobe *uprobe) 432a5f4374aSIngo Molnar { 433a5f4374aSIngo Molnar struct uprobe *u; 434a5f4374aSIngo Molnar 4356f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 436a5f4374aSIngo Molnar u = __insert_uprobe(uprobe); 4376f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 438a5f4374aSIngo Molnar 439a5f4374aSIngo Molnar return u; 440a5f4374aSIngo Molnar } 441a5f4374aSIngo Molnar 442a5f4374aSIngo Molnar static void put_uprobe(struct uprobe *uprobe) 443a5f4374aSIngo Molnar { 444a5f4374aSIngo Molnar if (atomic_dec_and_test(&uprobe->ref)) 445a5f4374aSIngo Molnar kfree(uprobe); 446a5f4374aSIngo Molnar } 447a5f4374aSIngo Molnar 448a5f4374aSIngo Molnar static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) 449a5f4374aSIngo Molnar { 450a5f4374aSIngo Molnar struct uprobe *uprobe, *cur_uprobe; 451a5f4374aSIngo Molnar 452a5f4374aSIngo Molnar uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); 453a5f4374aSIngo Molnar if (!uprobe) 454a5f4374aSIngo Molnar return NULL; 455a5f4374aSIngo Molnar 456a5f4374aSIngo Molnar uprobe->inode = igrab(inode); 457a5f4374aSIngo Molnar uprobe->offset = offset; 458e591c8d7SOleg Nesterov init_rwsem(&uprobe->register_rwsem); 459a5f4374aSIngo Molnar init_rwsem(&uprobe->consumer_rwsem); 460bbc33d05SOleg Nesterov /* For now assume that the instruction need not be single-stepped */ 461bbc33d05SOleg Nesterov __set_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); 462a5f4374aSIngo Molnar 463a5f4374aSIngo Molnar /* add to uprobes_tree, sorted on inode:offset */ 464a5f4374aSIngo Molnar cur_uprobe = insert_uprobe(uprobe); 465a5f4374aSIngo Molnar 466a5f4374aSIngo Molnar /* a uprobe exists for this inode:offset combination */ 467a5f4374aSIngo Molnar if (cur_uprobe) { 468a5f4374aSIngo Molnar kfree(uprobe); 469a5f4374aSIngo Molnar uprobe = cur_uprobe; 470a5f4374aSIngo Molnar iput(inode); 471a5f4374aSIngo Molnar } 472a5f4374aSIngo Molnar 473a5f4374aSIngo Molnar return uprobe; 474a5f4374aSIngo Molnar } 475a5f4374aSIngo Molnar 4769a98e03cSOleg Nesterov static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) 477a5f4374aSIngo Molnar { 478a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 479e3343e6aSSrikar Dronamraju uc->next = uprobe->consumers; 480e3343e6aSSrikar Dronamraju uprobe->consumers = uc; 481a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 482a5f4374aSIngo Molnar } 483a5f4374aSIngo Molnar 484a5f4374aSIngo Molnar /* 485e3343e6aSSrikar Dronamraju * For uprobe @uprobe, delete the consumer @uc. 486e3343e6aSSrikar Dronamraju * Return true if the @uc is deleted successfully 487a5f4374aSIngo Molnar * or return false. 488a5f4374aSIngo Molnar */ 489e3343e6aSSrikar Dronamraju static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) 490a5f4374aSIngo Molnar { 491a5f4374aSIngo Molnar struct uprobe_consumer **con; 492a5f4374aSIngo Molnar bool ret = false; 493a5f4374aSIngo Molnar 494a5f4374aSIngo Molnar down_write(&uprobe->consumer_rwsem); 495a5f4374aSIngo Molnar for (con = &uprobe->consumers; *con; con = &(*con)->next) { 496e3343e6aSSrikar Dronamraju if (*con == uc) { 497e3343e6aSSrikar Dronamraju *con = uc->next; 498a5f4374aSIngo Molnar ret = true; 499a5f4374aSIngo Molnar break; 500a5f4374aSIngo Molnar } 501a5f4374aSIngo Molnar } 502a5f4374aSIngo Molnar up_write(&uprobe->consumer_rwsem); 503a5f4374aSIngo Molnar 504a5f4374aSIngo Molnar return ret; 505a5f4374aSIngo Molnar } 506a5f4374aSIngo Molnar 507e3343e6aSSrikar Dronamraju static int 508d436615eSOleg Nesterov __copy_insn(struct address_space *mapping, struct file *filp, char *insn, 509593609a5SOleg Nesterov unsigned long nbytes, loff_t offset) 510a5f4374aSIngo Molnar { 511a5f4374aSIngo Molnar struct page *page; 512a5f4374aSIngo Molnar 513cc359d18SOleg Nesterov if (!mapping->a_ops->readpage) 514cc359d18SOleg Nesterov return -EIO; 515a5f4374aSIngo Molnar /* 516a5f4374aSIngo Molnar * Ensure that the page that has the original instruction is 517a5f4374aSIngo Molnar * populated and in page-cache. 518a5f4374aSIngo Molnar */ 5192edb7b55SOleg Nesterov page = read_mapping_page(mapping, offset >> PAGE_CACHE_SHIFT, filp); 520a5f4374aSIngo Molnar if (IS_ERR(page)) 521a5f4374aSIngo Molnar return PTR_ERR(page); 522a5f4374aSIngo Molnar 5232edb7b55SOleg Nesterov copy_from_page(page, offset, insn, nbytes); 524a5f4374aSIngo Molnar page_cache_release(page); 525a5f4374aSIngo Molnar 526a5f4374aSIngo Molnar return 0; 527a5f4374aSIngo Molnar } 528a5f4374aSIngo Molnar 529d436615eSOleg Nesterov static int copy_insn(struct uprobe *uprobe, struct file *filp) 530a5f4374aSIngo Molnar { 531a5f4374aSIngo Molnar struct address_space *mapping; 532a5f4374aSIngo Molnar unsigned long nbytes; 533a5f4374aSIngo Molnar int bytes; 534a5f4374aSIngo Molnar 535d436615eSOleg Nesterov nbytes = PAGE_SIZE - (uprobe->offset & ~PAGE_MASK); 536a5f4374aSIngo Molnar mapping = uprobe->inode->i_mapping; 537a5f4374aSIngo Molnar 538a5f4374aSIngo Molnar /* Instruction at end of binary; copy only available bytes */ 539a5f4374aSIngo Molnar if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size) 540a5f4374aSIngo Molnar bytes = uprobe->inode->i_size - uprobe->offset; 541a5f4374aSIngo Molnar else 542a5f4374aSIngo Molnar bytes = MAX_UINSN_BYTES; 543a5f4374aSIngo Molnar 544a5f4374aSIngo Molnar /* Instruction at the page-boundary; copy bytes in second page */ 545a5f4374aSIngo Molnar if (nbytes < bytes) { 546fc36f595SOleg Nesterov int err = __copy_insn(mapping, filp, uprobe->arch.insn + nbytes, 547fc36f595SOleg Nesterov bytes - nbytes, uprobe->offset + nbytes); 548fc36f595SOleg Nesterov if (err) 549fc36f595SOleg Nesterov return err; 550a5f4374aSIngo Molnar bytes = nbytes; 551a5f4374aSIngo Molnar } 552d436615eSOleg Nesterov return __copy_insn(mapping, filp, uprobe->arch.insn, bytes, uprobe->offset); 553a5f4374aSIngo Molnar } 554a5f4374aSIngo Molnar 555cb9a19feSOleg Nesterov static int prepare_uprobe(struct uprobe *uprobe, struct file *file, 556cb9a19feSOleg Nesterov struct mm_struct *mm, unsigned long vaddr) 557cb9a19feSOleg Nesterov { 558cb9a19feSOleg Nesterov int ret = 0; 559cb9a19feSOleg Nesterov 56071434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 561cb9a19feSOleg Nesterov return ret; 562cb9a19feSOleg Nesterov 563d4d3ccc6SOleg Nesterov /* TODO: move this into _register, until then we abuse this sem. */ 564d4d3ccc6SOleg Nesterov down_write(&uprobe->consumer_rwsem); 56571434f2fSOleg Nesterov if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) 5664710f05fSOleg Nesterov goto out; 5674710f05fSOleg Nesterov 568cb9a19feSOleg Nesterov ret = copy_insn(uprobe, file); 569cb9a19feSOleg Nesterov if (ret) 570cb9a19feSOleg Nesterov goto out; 571cb9a19feSOleg Nesterov 572cb9a19feSOleg Nesterov ret = -ENOTSUPP; 5730908ad6eSAnanth N Mavinakayanahalli if (is_trap_insn((uprobe_opcode_t *)uprobe->arch.insn)) 574cb9a19feSOleg Nesterov goto out; 575cb9a19feSOleg Nesterov 576cb9a19feSOleg Nesterov ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); 577cb9a19feSOleg Nesterov if (ret) 578cb9a19feSOleg Nesterov goto out; 579cb9a19feSOleg Nesterov 580cb9a19feSOleg Nesterov /* write_opcode() assumes we don't cross page boundary */ 581cb9a19feSOleg Nesterov BUG_ON((uprobe->offset & ~PAGE_MASK) + 582cb9a19feSOleg Nesterov UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); 583cb9a19feSOleg Nesterov 584cb9a19feSOleg Nesterov smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ 58571434f2fSOleg Nesterov set_bit(UPROBE_COPY_INSN, &uprobe->flags); 586cb9a19feSOleg Nesterov 587cb9a19feSOleg Nesterov out: 588d4d3ccc6SOleg Nesterov up_write(&uprobe->consumer_rwsem); 5894710f05fSOleg Nesterov 590cb9a19feSOleg Nesterov return ret; 591cb9a19feSOleg Nesterov } 592cb9a19feSOleg Nesterov 5938a7f2fa0SOleg Nesterov static inline bool consumer_filter(struct uprobe_consumer *uc, 5948a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 595806a98bdSOleg Nesterov { 5968a7f2fa0SOleg Nesterov return !uc->filter || uc->filter(uc, ctx, mm); 597806a98bdSOleg Nesterov } 598806a98bdSOleg Nesterov 5998a7f2fa0SOleg Nesterov static bool filter_chain(struct uprobe *uprobe, 6008a7f2fa0SOleg Nesterov enum uprobe_filter_ctx ctx, struct mm_struct *mm) 60163633cbfSOleg Nesterov { 6021ff6fee5SOleg Nesterov struct uprobe_consumer *uc; 6031ff6fee5SOleg Nesterov bool ret = false; 6041ff6fee5SOleg Nesterov 6051ff6fee5SOleg Nesterov down_read(&uprobe->consumer_rwsem); 6061ff6fee5SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 6078a7f2fa0SOleg Nesterov ret = consumer_filter(uc, ctx, mm); 6081ff6fee5SOleg Nesterov if (ret) 6091ff6fee5SOleg Nesterov break; 6101ff6fee5SOleg Nesterov } 6111ff6fee5SOleg Nesterov up_read(&uprobe->consumer_rwsem); 6121ff6fee5SOleg Nesterov 6131ff6fee5SOleg Nesterov return ret; 61463633cbfSOleg Nesterov } 61563633cbfSOleg Nesterov 616e3343e6aSSrikar Dronamraju static int 617e3343e6aSSrikar Dronamraju install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, 618816c03fbSOleg Nesterov struct vm_area_struct *vma, unsigned long vaddr) 619a5f4374aSIngo Molnar { 620f8ac4ec9SOleg Nesterov bool first_uprobe; 621a5f4374aSIngo Molnar int ret; 622a5f4374aSIngo Molnar 623cb9a19feSOleg Nesterov ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); 624a5f4374aSIngo Molnar if (ret) 625a5f4374aSIngo Molnar return ret; 626a5f4374aSIngo Molnar 627f8ac4ec9SOleg Nesterov /* 628f8ac4ec9SOleg Nesterov * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), 629f8ac4ec9SOleg Nesterov * the task can hit this breakpoint right after __replace_page(). 630f8ac4ec9SOleg Nesterov */ 631f8ac4ec9SOleg Nesterov first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); 632f8ac4ec9SOleg Nesterov if (first_uprobe) 633f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &mm->flags); 634f8ac4ec9SOleg Nesterov 635816c03fbSOleg Nesterov ret = set_swbp(&uprobe->arch, mm, vaddr); 6369f68f672SOleg Nesterov if (!ret) 6379f68f672SOleg Nesterov clear_bit(MMF_RECALC_UPROBES, &mm->flags); 6389f68f672SOleg Nesterov else if (first_uprobe) 639f8ac4ec9SOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 640a5f4374aSIngo Molnar 641a5f4374aSIngo Molnar return ret; 642a5f4374aSIngo Molnar } 643a5f4374aSIngo Molnar 644076a365bSOleg Nesterov static int 645816c03fbSOleg Nesterov remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) 646a5f4374aSIngo Molnar { 6479f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &mm->flags); 648076a365bSOleg Nesterov return set_orig_insn(&uprobe->arch, mm, vaddr); 649a5f4374aSIngo Molnar } 650a5f4374aSIngo Molnar 65106b7bcd8SOleg Nesterov static inline bool uprobe_is_active(struct uprobe *uprobe) 65206b7bcd8SOleg Nesterov { 65306b7bcd8SOleg Nesterov return !RB_EMPTY_NODE(&uprobe->rb_node); 65406b7bcd8SOleg Nesterov } 6550326f5a9SSrikar Dronamraju /* 656778b032dSOleg Nesterov * There could be threads that have already hit the breakpoint. They 657778b032dSOleg Nesterov * will recheck the current insn and restart if find_uprobe() fails. 658778b032dSOleg Nesterov * See find_active_uprobe(). 6590326f5a9SSrikar Dronamraju */ 660a5f4374aSIngo Molnar static void delete_uprobe(struct uprobe *uprobe) 661a5f4374aSIngo Molnar { 66206b7bcd8SOleg Nesterov if (WARN_ON(!uprobe_is_active(uprobe))) 66306b7bcd8SOleg Nesterov return; 66406b7bcd8SOleg Nesterov 6656f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 666a5f4374aSIngo Molnar rb_erase(&uprobe->rb_node, &uprobes_tree); 6676f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 66806b7bcd8SOleg Nesterov RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ 669a5f4374aSIngo Molnar iput(uprobe->inode); 670a5f4374aSIngo Molnar put_uprobe(uprobe); 671a5f4374aSIngo Molnar } 672a5f4374aSIngo Molnar 67326872090SOleg Nesterov struct map_info { 67426872090SOleg Nesterov struct map_info *next; 67526872090SOleg Nesterov struct mm_struct *mm; 676816c03fbSOleg Nesterov unsigned long vaddr; 67726872090SOleg Nesterov }; 67826872090SOleg Nesterov 67926872090SOleg Nesterov static inline struct map_info *free_map_info(struct map_info *info) 680a5f4374aSIngo Molnar { 68126872090SOleg Nesterov struct map_info *next = info->next; 68226872090SOleg Nesterov kfree(info); 68326872090SOleg Nesterov return next; 68426872090SOleg Nesterov } 68526872090SOleg Nesterov 68626872090SOleg Nesterov static struct map_info * 68726872090SOleg Nesterov build_map_info(struct address_space *mapping, loff_t offset, bool is_register) 68826872090SOleg Nesterov { 68926872090SOleg Nesterov unsigned long pgoff = offset >> PAGE_SHIFT; 690a5f4374aSIngo Molnar struct vm_area_struct *vma; 69126872090SOleg Nesterov struct map_info *curr = NULL; 69226872090SOleg Nesterov struct map_info *prev = NULL; 69326872090SOleg Nesterov struct map_info *info; 69426872090SOleg Nesterov int more = 0; 695a5f4374aSIngo Molnar 69626872090SOleg Nesterov again: 69726872090SOleg Nesterov mutex_lock(&mapping->i_mmap_mutex); 6986b2dbba8SMichel Lespinasse vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { 699a5f4374aSIngo Molnar if (!valid_vma(vma, is_register)) 700a5f4374aSIngo Molnar continue; 701a5f4374aSIngo Molnar 7027a5bfb66SOleg Nesterov if (!prev && !more) { 7037a5bfb66SOleg Nesterov /* 7047a5bfb66SOleg Nesterov * Needs GFP_NOWAIT to avoid i_mmap_mutex recursion through 7057a5bfb66SOleg Nesterov * reclaim. This is optimistic, no harm done if it fails. 7067a5bfb66SOleg Nesterov */ 7077a5bfb66SOleg Nesterov prev = kmalloc(sizeof(struct map_info), 7087a5bfb66SOleg Nesterov GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); 7097a5bfb66SOleg Nesterov if (prev) 7107a5bfb66SOleg Nesterov prev->next = NULL; 7117a5bfb66SOleg Nesterov } 71226872090SOleg Nesterov if (!prev) { 71326872090SOleg Nesterov more++; 71426872090SOleg Nesterov continue; 715a5f4374aSIngo Molnar } 716a5f4374aSIngo Molnar 71726872090SOleg Nesterov if (!atomic_inc_not_zero(&vma->vm_mm->mm_users)) 71826872090SOleg Nesterov continue; 719a5f4374aSIngo Molnar 72026872090SOleg Nesterov info = prev; 72126872090SOleg Nesterov prev = prev->next; 72226872090SOleg Nesterov info->next = curr; 72326872090SOleg Nesterov curr = info; 72426872090SOleg Nesterov 72526872090SOleg Nesterov info->mm = vma->vm_mm; 72657683f72SOleg Nesterov info->vaddr = offset_to_vaddr(vma, offset); 727a5f4374aSIngo Molnar } 728a5f4374aSIngo Molnar mutex_unlock(&mapping->i_mmap_mutex); 729a5f4374aSIngo Molnar 73026872090SOleg Nesterov if (!more) 73126872090SOleg Nesterov goto out; 732a5f4374aSIngo Molnar 73326872090SOleg Nesterov prev = curr; 73426872090SOleg Nesterov while (curr) { 73526872090SOleg Nesterov mmput(curr->mm); 73626872090SOleg Nesterov curr = curr->next; 73726872090SOleg Nesterov } 73826872090SOleg Nesterov 73926872090SOleg Nesterov do { 74026872090SOleg Nesterov info = kmalloc(sizeof(struct map_info), GFP_KERNEL); 74126872090SOleg Nesterov if (!info) { 74226872090SOleg Nesterov curr = ERR_PTR(-ENOMEM); 74326872090SOleg Nesterov goto out; 74426872090SOleg Nesterov } 74526872090SOleg Nesterov info->next = prev; 74626872090SOleg Nesterov prev = info; 74726872090SOleg Nesterov } while (--more); 74826872090SOleg Nesterov 74926872090SOleg Nesterov goto again; 75026872090SOleg Nesterov out: 75126872090SOleg Nesterov while (prev) 75226872090SOleg Nesterov prev = free_map_info(prev); 75326872090SOleg Nesterov return curr; 754a5f4374aSIngo Molnar } 755a5f4374aSIngo Molnar 756bdf8647cSOleg Nesterov static int 757bdf8647cSOleg Nesterov register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) 758a5f4374aSIngo Molnar { 759bdf8647cSOleg Nesterov bool is_register = !!new; 76026872090SOleg Nesterov struct map_info *info; 76126872090SOleg Nesterov int err = 0; 76226872090SOleg Nesterov 76332cdba1eSOleg Nesterov percpu_down_write(&dup_mmap_sem); 76426872090SOleg Nesterov info = build_map_info(uprobe->inode->i_mapping, 76526872090SOleg Nesterov uprobe->offset, is_register); 76632cdba1eSOleg Nesterov if (IS_ERR(info)) { 76732cdba1eSOleg Nesterov err = PTR_ERR(info); 76832cdba1eSOleg Nesterov goto out; 76932cdba1eSOleg Nesterov } 77026872090SOleg Nesterov 77126872090SOleg Nesterov while (info) { 77226872090SOleg Nesterov struct mm_struct *mm = info->mm; 773a5f4374aSIngo Molnar struct vm_area_struct *vma; 774a5f4374aSIngo Molnar 775076a365bSOleg Nesterov if (err && is_register) 77626872090SOleg Nesterov goto free; 777a5f4374aSIngo Molnar 77877fc4af1SOleg Nesterov down_write(&mm->mmap_sem); 779f4d6dfe5SOleg Nesterov vma = find_vma(mm, info->vaddr); 780f4d6dfe5SOleg Nesterov if (!vma || !valid_vma(vma, is_register) || 781f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 78226872090SOleg Nesterov goto unlock; 78326872090SOleg Nesterov 784f4d6dfe5SOleg Nesterov if (vma->vm_start > info->vaddr || 785f4d6dfe5SOleg Nesterov vaddr_to_offset(vma, info->vaddr) != uprobe->offset) 78626872090SOleg Nesterov goto unlock; 787a5f4374aSIngo Molnar 788806a98bdSOleg Nesterov if (is_register) { 789806a98bdSOleg Nesterov /* consult only the "caller", new consumer. */ 790bdf8647cSOleg Nesterov if (consumer_filter(new, 7918a7f2fa0SOleg Nesterov UPROBE_FILTER_REGISTER, mm)) 79226872090SOleg Nesterov err = install_breakpoint(uprobe, mm, vma, info->vaddr); 793806a98bdSOleg Nesterov } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { 7948a7f2fa0SOleg Nesterov if (!filter_chain(uprobe, 7958a7f2fa0SOleg Nesterov UPROBE_FILTER_UNREGISTER, mm)) 796076a365bSOleg Nesterov err |= remove_breakpoint(uprobe, mm, info->vaddr); 797806a98bdSOleg Nesterov } 79878f74116SOleg Nesterov 79926872090SOleg Nesterov unlock: 80026872090SOleg Nesterov up_write(&mm->mmap_sem); 80126872090SOleg Nesterov free: 80226872090SOleg Nesterov mmput(mm); 80326872090SOleg Nesterov info = free_map_info(info); 804a5f4374aSIngo Molnar } 80532cdba1eSOleg Nesterov out: 80632cdba1eSOleg Nesterov percpu_up_write(&dup_mmap_sem); 80726872090SOleg Nesterov return err; 808a5f4374aSIngo Molnar } 809a5f4374aSIngo Molnar 8109a98e03cSOleg Nesterov static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) 811a5f4374aSIngo Molnar { 8129a98e03cSOleg Nesterov consumer_add(uprobe, uc); 813bdf8647cSOleg Nesterov return register_for_each_vma(uprobe, uc); 814a5f4374aSIngo Molnar } 815a5f4374aSIngo Molnar 81604aab9b2SOleg Nesterov static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) 817a5f4374aSIngo Molnar { 81804aab9b2SOleg Nesterov int err; 819a5f4374aSIngo Molnar 82004aab9b2SOleg Nesterov if (!consumer_del(uprobe, uc)) /* WARN? */ 82104aab9b2SOleg Nesterov return; 82204aab9b2SOleg Nesterov 823bdf8647cSOleg Nesterov err = register_for_each_vma(uprobe, NULL); 824a5f4374aSIngo Molnar /* TODO : cant unregister? schedule a worker thread */ 825bb929284SOleg Nesterov if (!uprobe->consumers && !err) 82604aab9b2SOleg Nesterov delete_uprobe(uprobe); 82704aab9b2SOleg Nesterov } 828a5f4374aSIngo Molnar 829a5f4374aSIngo Molnar /* 830a5f4374aSIngo Molnar * uprobe_register - register a probe 831a5f4374aSIngo Molnar * @inode: the file in which the probe has to be placed. 832a5f4374aSIngo Molnar * @offset: offset from the start of the file. 833e3343e6aSSrikar Dronamraju * @uc: information on howto handle the probe.. 834a5f4374aSIngo Molnar * 835a5f4374aSIngo Molnar * Apart from the access refcount, uprobe_register() takes a creation 836a5f4374aSIngo Molnar * refcount (thro alloc_uprobe) if and only if this @uprobe is getting 837a5f4374aSIngo Molnar * inserted into the rbtree (i.e first consumer for a @inode:@offset 838a5f4374aSIngo Molnar * tuple). Creation refcount stops uprobe_unregister from freeing the 839a5f4374aSIngo Molnar * @uprobe even before the register operation is complete. Creation 840e3343e6aSSrikar Dronamraju * refcount is released when the last @uc for the @uprobe 841a5f4374aSIngo Molnar * unregisters. 842a5f4374aSIngo Molnar * 843a5f4374aSIngo Molnar * Return errno if it cannot successully install probes 844a5f4374aSIngo Molnar * else return 0 (success) 845a5f4374aSIngo Molnar */ 846e3343e6aSSrikar Dronamraju int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 847a5f4374aSIngo Molnar { 848a5f4374aSIngo Molnar struct uprobe *uprobe; 849a5f4374aSIngo Molnar int ret; 850a5f4374aSIngo Molnar 851ea024870SAnton Arapov /* Uprobe must have at least one set consumer */ 852ea024870SAnton Arapov if (!uc->handler && !uc->ret_handler) 853ea024870SAnton Arapov return -EINVAL; 854ea024870SAnton Arapov 855f0744af7SOleg Nesterov /* Racy, just to catch the obvious mistakes */ 856a5f4374aSIngo Molnar if (offset > i_size_read(inode)) 857a5f4374aSIngo Molnar return -EINVAL; 858a5f4374aSIngo Molnar 85966d06dffSOleg Nesterov retry: 860a5f4374aSIngo Molnar uprobe = alloc_uprobe(inode, offset); 86166d06dffSOleg Nesterov if (!uprobe) 86266d06dffSOleg Nesterov return -ENOMEM; 86366d06dffSOleg Nesterov /* 86466d06dffSOleg Nesterov * We can race with uprobe_unregister()->delete_uprobe(). 86566d06dffSOleg Nesterov * Check uprobe_is_active() and retry if it is false. 86666d06dffSOleg Nesterov */ 867e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 86866d06dffSOleg Nesterov ret = -EAGAIN; 86966d06dffSOleg Nesterov if (likely(uprobe_is_active(uprobe))) { 8709a98e03cSOleg Nesterov ret = __uprobe_register(uprobe, uc); 8719a98e03cSOleg Nesterov if (ret) 87204aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 873a5f4374aSIngo Molnar } 87466d06dffSOleg Nesterov up_write(&uprobe->register_rwsem); 875a5f4374aSIngo Molnar put_uprobe(uprobe); 876a5f4374aSIngo Molnar 87766d06dffSOleg Nesterov if (unlikely(ret == -EAGAIN)) 87866d06dffSOleg Nesterov goto retry; 879a5f4374aSIngo Molnar return ret; 880a5f4374aSIngo Molnar } 881e8440c14SJosh Stone EXPORT_SYMBOL_GPL(uprobe_register); 882a5f4374aSIngo Molnar 883a5f4374aSIngo Molnar /* 884bdf8647cSOleg Nesterov * uprobe_apply - unregister a already registered probe. 885bdf8647cSOleg Nesterov * @inode: the file in which the probe has to be removed. 886bdf8647cSOleg Nesterov * @offset: offset from the start of the file. 887bdf8647cSOleg Nesterov * @uc: consumer which wants to add more or remove some breakpoints 888bdf8647cSOleg Nesterov * @add: add or remove the breakpoints 889bdf8647cSOleg Nesterov */ 890bdf8647cSOleg Nesterov int uprobe_apply(struct inode *inode, loff_t offset, 891bdf8647cSOleg Nesterov struct uprobe_consumer *uc, bool add) 892bdf8647cSOleg Nesterov { 893bdf8647cSOleg Nesterov struct uprobe *uprobe; 894bdf8647cSOleg Nesterov struct uprobe_consumer *con; 895bdf8647cSOleg Nesterov int ret = -ENOENT; 896bdf8647cSOleg Nesterov 897bdf8647cSOleg Nesterov uprobe = find_uprobe(inode, offset); 898bdf8647cSOleg Nesterov if (!uprobe) 899bdf8647cSOleg Nesterov return ret; 900bdf8647cSOleg Nesterov 901bdf8647cSOleg Nesterov down_write(&uprobe->register_rwsem); 902bdf8647cSOleg Nesterov for (con = uprobe->consumers; con && con != uc ; con = con->next) 903bdf8647cSOleg Nesterov ; 904bdf8647cSOleg Nesterov if (con) 905bdf8647cSOleg Nesterov ret = register_for_each_vma(uprobe, add ? uc : NULL); 906bdf8647cSOleg Nesterov up_write(&uprobe->register_rwsem); 907bdf8647cSOleg Nesterov put_uprobe(uprobe); 908bdf8647cSOleg Nesterov 909bdf8647cSOleg Nesterov return ret; 910bdf8647cSOleg Nesterov } 911bdf8647cSOleg Nesterov 912bdf8647cSOleg Nesterov /* 913a5f4374aSIngo Molnar * uprobe_unregister - unregister a already registered probe. 914a5f4374aSIngo Molnar * @inode: the file in which the probe has to be removed. 915a5f4374aSIngo Molnar * @offset: offset from the start of the file. 916e3343e6aSSrikar Dronamraju * @uc: identify which probe if multiple probes are colocated. 917a5f4374aSIngo Molnar */ 918e3343e6aSSrikar Dronamraju void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) 919a5f4374aSIngo Molnar { 920a5f4374aSIngo Molnar struct uprobe *uprobe; 921a5f4374aSIngo Molnar 922a5f4374aSIngo Molnar uprobe = find_uprobe(inode, offset); 923a5f4374aSIngo Molnar if (!uprobe) 924a5f4374aSIngo Molnar return; 925a5f4374aSIngo Molnar 926e591c8d7SOleg Nesterov down_write(&uprobe->register_rwsem); 92704aab9b2SOleg Nesterov __uprobe_unregister(uprobe, uc); 928e591c8d7SOleg Nesterov up_write(&uprobe->register_rwsem); 929a5f4374aSIngo Molnar put_uprobe(uprobe); 930a5f4374aSIngo Molnar } 931e8440c14SJosh Stone EXPORT_SYMBOL_GPL(uprobe_unregister); 932a5f4374aSIngo Molnar 933da1816b1SOleg Nesterov static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) 934da1816b1SOleg Nesterov { 935da1816b1SOleg Nesterov struct vm_area_struct *vma; 936da1816b1SOleg Nesterov int err = 0; 937da1816b1SOleg Nesterov 938da1816b1SOleg Nesterov down_read(&mm->mmap_sem); 939da1816b1SOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 940da1816b1SOleg Nesterov unsigned long vaddr; 941da1816b1SOleg Nesterov loff_t offset; 942da1816b1SOleg Nesterov 943da1816b1SOleg Nesterov if (!valid_vma(vma, false) || 944f281769eSOleg Nesterov file_inode(vma->vm_file) != uprobe->inode) 945da1816b1SOleg Nesterov continue; 946da1816b1SOleg Nesterov 947da1816b1SOleg Nesterov offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; 948da1816b1SOleg Nesterov if (uprobe->offset < offset || 949da1816b1SOleg Nesterov uprobe->offset >= offset + vma->vm_end - vma->vm_start) 950da1816b1SOleg Nesterov continue; 951da1816b1SOleg Nesterov 952da1816b1SOleg Nesterov vaddr = offset_to_vaddr(vma, uprobe->offset); 953da1816b1SOleg Nesterov err |= remove_breakpoint(uprobe, mm, vaddr); 954da1816b1SOleg Nesterov } 955da1816b1SOleg Nesterov up_read(&mm->mmap_sem); 956da1816b1SOleg Nesterov 957da1816b1SOleg Nesterov return err; 958da1816b1SOleg Nesterov } 959da1816b1SOleg Nesterov 960891c3970SOleg Nesterov static struct rb_node * 961891c3970SOleg Nesterov find_node_in_range(struct inode *inode, loff_t min, loff_t max) 962a5f4374aSIngo Molnar { 963a5f4374aSIngo Molnar struct rb_node *n = uprobes_tree.rb_node; 964a5f4374aSIngo Molnar 965a5f4374aSIngo Molnar while (n) { 966891c3970SOleg Nesterov struct uprobe *u = rb_entry(n, struct uprobe, rb_node); 967a5f4374aSIngo Molnar 968891c3970SOleg Nesterov if (inode < u->inode) { 969a5f4374aSIngo Molnar n = n->rb_left; 970891c3970SOleg Nesterov } else if (inode > u->inode) { 971a5f4374aSIngo Molnar n = n->rb_right; 972891c3970SOleg Nesterov } else { 973891c3970SOleg Nesterov if (max < u->offset) 974891c3970SOleg Nesterov n = n->rb_left; 975891c3970SOleg Nesterov else if (min > u->offset) 976891c3970SOleg Nesterov n = n->rb_right; 977891c3970SOleg Nesterov else 978891c3970SOleg Nesterov break; 979891c3970SOleg Nesterov } 980a5f4374aSIngo Molnar } 981a5f4374aSIngo Molnar 982891c3970SOleg Nesterov return n; 983a5f4374aSIngo Molnar } 984a5f4374aSIngo Molnar 985a5f4374aSIngo Molnar /* 986891c3970SOleg Nesterov * For a given range in vma, build a list of probes that need to be inserted. 987a5f4374aSIngo Molnar */ 988891c3970SOleg Nesterov static void build_probe_list(struct inode *inode, 989891c3970SOleg Nesterov struct vm_area_struct *vma, 990891c3970SOleg Nesterov unsigned long start, unsigned long end, 991891c3970SOleg Nesterov struct list_head *head) 992a5f4374aSIngo Molnar { 993891c3970SOleg Nesterov loff_t min, max; 994891c3970SOleg Nesterov struct rb_node *n, *t; 995891c3970SOleg Nesterov struct uprobe *u; 996891c3970SOleg Nesterov 997891c3970SOleg Nesterov INIT_LIST_HEAD(head); 998cb113b47SOleg Nesterov min = vaddr_to_offset(vma, start); 999891c3970SOleg Nesterov max = min + (end - start) - 1; 1000a5f4374aSIngo Molnar 10016f47caa0SOleg Nesterov spin_lock(&uprobes_treelock); 1002891c3970SOleg Nesterov n = find_node_in_range(inode, min, max); 1003891c3970SOleg Nesterov if (n) { 1004891c3970SOleg Nesterov for (t = n; t; t = rb_prev(t)) { 1005891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1006891c3970SOleg Nesterov if (u->inode != inode || u->offset < min) 1007a5f4374aSIngo Molnar break; 1008891c3970SOleg Nesterov list_add(&u->pending_list, head); 1009891c3970SOleg Nesterov atomic_inc(&u->ref); 1010a5f4374aSIngo Molnar } 1011891c3970SOleg Nesterov for (t = n; (t = rb_next(t)); ) { 1012891c3970SOleg Nesterov u = rb_entry(t, struct uprobe, rb_node); 1013891c3970SOleg Nesterov if (u->inode != inode || u->offset > max) 1014891c3970SOleg Nesterov break; 1015891c3970SOleg Nesterov list_add(&u->pending_list, head); 1016891c3970SOleg Nesterov atomic_inc(&u->ref); 1017891c3970SOleg Nesterov } 1018891c3970SOleg Nesterov } 10196f47caa0SOleg Nesterov spin_unlock(&uprobes_treelock); 1020a5f4374aSIngo Molnar } 1021a5f4374aSIngo Molnar 1022a5f4374aSIngo Molnar /* 10235e5be71aSOleg Nesterov * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. 1024a5f4374aSIngo Molnar * 10255e5be71aSOleg Nesterov * Currently we ignore all errors and always return 0, the callers 10265e5be71aSOleg Nesterov * can't handle the failure anyway. 1027a5f4374aSIngo Molnar */ 1028a5f4374aSIngo Molnar int uprobe_mmap(struct vm_area_struct *vma) 1029a5f4374aSIngo Molnar { 1030a5f4374aSIngo Molnar struct list_head tmp_list; 1031665605a2SOleg Nesterov struct uprobe *uprobe, *u; 1032a5f4374aSIngo Molnar struct inode *inode; 1033a5f4374aSIngo Molnar 1034441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, true)) 1035a5f4374aSIngo Molnar return 0; 1036a5f4374aSIngo Molnar 1037f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 1038a5f4374aSIngo Molnar if (!inode) 1039a5f4374aSIngo Molnar return 0; 1040a5f4374aSIngo Molnar 1041a5f4374aSIngo Molnar mutex_lock(uprobes_mmap_hash(inode)); 1042891c3970SOleg Nesterov build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); 1043806a98bdSOleg Nesterov /* 1044806a98bdSOleg Nesterov * We can race with uprobe_unregister(), this uprobe can be already 1045806a98bdSOleg Nesterov * removed. But in this case filter_chain() must return false, all 1046806a98bdSOleg Nesterov * consumers have gone away. 1047806a98bdSOleg Nesterov */ 1048665605a2SOleg Nesterov list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { 1049806a98bdSOleg Nesterov if (!fatal_signal_pending(current) && 10508a7f2fa0SOleg Nesterov filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { 105157683f72SOleg Nesterov unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); 10525e5be71aSOleg Nesterov install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); 1053a5f4374aSIngo Molnar } 1054a5f4374aSIngo Molnar put_uprobe(uprobe); 1055a5f4374aSIngo Molnar } 1056a5f4374aSIngo Molnar mutex_unlock(uprobes_mmap_hash(inode)); 1057a5f4374aSIngo Molnar 10585e5be71aSOleg Nesterov return 0; 1059a5f4374aSIngo Molnar } 1060a5f4374aSIngo Molnar 10619f68f672SOleg Nesterov static bool 10629f68f672SOleg Nesterov vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) 10639f68f672SOleg Nesterov { 10649f68f672SOleg Nesterov loff_t min, max; 10659f68f672SOleg Nesterov struct inode *inode; 10669f68f672SOleg Nesterov struct rb_node *n; 10679f68f672SOleg Nesterov 1068f281769eSOleg Nesterov inode = file_inode(vma->vm_file); 10699f68f672SOleg Nesterov 10709f68f672SOleg Nesterov min = vaddr_to_offset(vma, start); 10719f68f672SOleg Nesterov max = min + (end - start) - 1; 10729f68f672SOleg Nesterov 10739f68f672SOleg Nesterov spin_lock(&uprobes_treelock); 10749f68f672SOleg Nesterov n = find_node_in_range(inode, min, max); 10759f68f672SOleg Nesterov spin_unlock(&uprobes_treelock); 10769f68f672SOleg Nesterov 10779f68f672SOleg Nesterov return !!n; 10789f68f672SOleg Nesterov } 10799f68f672SOleg Nesterov 1080682968e0SSrikar Dronamraju /* 1081682968e0SSrikar Dronamraju * Called in context of a munmap of a vma. 1082682968e0SSrikar Dronamraju */ 1083cbc91f71SSrikar Dronamraju void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) 1084682968e0SSrikar Dronamraju { 1085441f1eb7SOleg Nesterov if (no_uprobe_events() || !valid_vma(vma, false)) 1086682968e0SSrikar Dronamraju return; 1087682968e0SSrikar Dronamraju 10882fd611a9SOleg Nesterov if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ 10892fd611a9SOleg Nesterov return; 10902fd611a9SOleg Nesterov 10919f68f672SOleg Nesterov if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || 10929f68f672SOleg Nesterov test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) 1093f8ac4ec9SOleg Nesterov return; 1094f8ac4ec9SOleg Nesterov 10959f68f672SOleg Nesterov if (vma_has_uprobes(vma, start, end)) 10969f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); 1097682968e0SSrikar Dronamraju } 1098682968e0SSrikar Dronamraju 1099d4b3b638SSrikar Dronamraju /* Slot allocation for XOL */ 11006441ec8bSOleg Nesterov static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) 1101d4b3b638SSrikar Dronamraju { 1102c8a82538SOleg Nesterov int ret = -EALREADY; 1103d4b3b638SSrikar Dronamraju 1104d4b3b638SSrikar Dronamraju down_write(&mm->mmap_sem); 1105d4b3b638SSrikar Dronamraju if (mm->uprobes_state.xol_area) 1106d4b3b638SSrikar Dronamraju goto fail; 1107d4b3b638SSrikar Dronamraju 1108af0d95afSOleg Nesterov if (!area->vaddr) { 1109d4b3b638SSrikar Dronamraju /* Try to map as high as possible, this is only a hint. */ 1110af0d95afSOleg Nesterov area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, 1111af0d95afSOleg Nesterov PAGE_SIZE, 0, 0); 1112d4b3b638SSrikar Dronamraju if (area->vaddr & ~PAGE_MASK) { 1113d4b3b638SSrikar Dronamraju ret = area->vaddr; 1114d4b3b638SSrikar Dronamraju goto fail; 1115d4b3b638SSrikar Dronamraju } 1116af0d95afSOleg Nesterov } 1117d4b3b638SSrikar Dronamraju 1118d4b3b638SSrikar Dronamraju ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, 1119d4b3b638SSrikar Dronamraju VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page); 1120d4b3b638SSrikar Dronamraju if (ret) 1121d4b3b638SSrikar Dronamraju goto fail; 1122d4b3b638SSrikar Dronamraju 1123d4b3b638SSrikar Dronamraju smp_wmb(); /* pairs with get_xol_area() */ 1124d4b3b638SSrikar Dronamraju mm->uprobes_state.xol_area = area; 1125d4b3b638SSrikar Dronamraju fail: 1126d4b3b638SSrikar Dronamraju up_write(&mm->mmap_sem); 1127d4b3b638SSrikar Dronamraju 1128d4b3b638SSrikar Dronamraju return ret; 1129d4b3b638SSrikar Dronamraju } 1130d4b3b638SSrikar Dronamraju 1131af0d95afSOleg Nesterov static struct xol_area *__create_xol_area(unsigned long vaddr) 1132d4b3b638SSrikar Dronamraju { 11339b545df8SOleg Nesterov struct mm_struct *mm = current->mm; 1134e78aebfdSAnton Arapov uprobe_opcode_t insn = UPROBE_SWBP_INSN; 11356441ec8bSOleg Nesterov struct xol_area *area; 11369b545df8SOleg Nesterov 1137af0d95afSOleg Nesterov area = kmalloc(sizeof(*area), GFP_KERNEL); 1138d4b3b638SSrikar Dronamraju if (unlikely(!area)) 1139c8a82538SOleg Nesterov goto out; 1140d4b3b638SSrikar Dronamraju 1141d4b3b638SSrikar Dronamraju area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); 1142d4b3b638SSrikar Dronamraju if (!area->bitmap) 1143c8a82538SOleg Nesterov goto free_area; 1144c8a82538SOleg Nesterov 1145c8a82538SOleg Nesterov area->page = alloc_page(GFP_HIGHUSER); 1146c8a82538SOleg Nesterov if (!area->page) 1147c8a82538SOleg Nesterov goto free_bitmap; 1148d4b3b638SSrikar Dronamraju 1149af0d95afSOleg Nesterov area->vaddr = vaddr; 1150d4b3b638SSrikar Dronamraju init_waitqueue_head(&area->wq); 11516441ec8bSOleg Nesterov /* Reserve the 1st slot for get_trampoline_vaddr() */ 11526441ec8bSOleg Nesterov set_bit(0, area->bitmap); 11536441ec8bSOleg Nesterov atomic_set(&area->slot_count, 1); 11546441ec8bSOleg Nesterov copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE); 1155e78aebfdSAnton Arapov 11566441ec8bSOleg Nesterov if (!xol_add_vma(mm, area)) 1157d4b3b638SSrikar Dronamraju return area; 1158d4b3b638SSrikar Dronamraju 1159c8a82538SOleg Nesterov __free_page(area->page); 1160c8a82538SOleg Nesterov free_bitmap: 1161d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1162c8a82538SOleg Nesterov free_area: 1163d4b3b638SSrikar Dronamraju kfree(area); 1164c8a82538SOleg Nesterov out: 11656441ec8bSOleg Nesterov return NULL; 11666441ec8bSOleg Nesterov } 11676441ec8bSOleg Nesterov 11686441ec8bSOleg Nesterov /* 11696441ec8bSOleg Nesterov * get_xol_area - Allocate process's xol_area if necessary. 11706441ec8bSOleg Nesterov * This area will be used for storing instructions for execution out of line. 11716441ec8bSOleg Nesterov * 11726441ec8bSOleg Nesterov * Returns the allocated area or NULL. 11736441ec8bSOleg Nesterov */ 11746441ec8bSOleg Nesterov static struct xol_area *get_xol_area(void) 11756441ec8bSOleg Nesterov { 11766441ec8bSOleg Nesterov struct mm_struct *mm = current->mm; 11776441ec8bSOleg Nesterov struct xol_area *area; 11786441ec8bSOleg Nesterov 11796441ec8bSOleg Nesterov if (!mm->uprobes_state.xol_area) 1180af0d95afSOleg Nesterov __create_xol_area(0); 11816441ec8bSOleg Nesterov 11829b545df8SOleg Nesterov area = mm->uprobes_state.xol_area; 11839b545df8SOleg Nesterov smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ 11849b545df8SOleg Nesterov return area; 1185d4b3b638SSrikar Dronamraju } 1186d4b3b638SSrikar Dronamraju 1187d4b3b638SSrikar Dronamraju /* 1188d4b3b638SSrikar Dronamraju * uprobe_clear_state - Free the area allocated for slots. 1189d4b3b638SSrikar Dronamraju */ 1190d4b3b638SSrikar Dronamraju void uprobe_clear_state(struct mm_struct *mm) 1191d4b3b638SSrikar Dronamraju { 1192d4b3b638SSrikar Dronamraju struct xol_area *area = mm->uprobes_state.xol_area; 1193d4b3b638SSrikar Dronamraju 1194d4b3b638SSrikar Dronamraju if (!area) 1195d4b3b638SSrikar Dronamraju return; 1196d4b3b638SSrikar Dronamraju 1197d4b3b638SSrikar Dronamraju put_page(area->page); 1198d4b3b638SSrikar Dronamraju kfree(area->bitmap); 1199d4b3b638SSrikar Dronamraju kfree(area); 1200d4b3b638SSrikar Dronamraju } 1201d4b3b638SSrikar Dronamraju 120232cdba1eSOleg Nesterov void uprobe_start_dup_mmap(void) 120332cdba1eSOleg Nesterov { 120432cdba1eSOleg Nesterov percpu_down_read(&dup_mmap_sem); 120532cdba1eSOleg Nesterov } 120632cdba1eSOleg Nesterov 120732cdba1eSOleg Nesterov void uprobe_end_dup_mmap(void) 120832cdba1eSOleg Nesterov { 120932cdba1eSOleg Nesterov percpu_up_read(&dup_mmap_sem); 121032cdba1eSOleg Nesterov } 121132cdba1eSOleg Nesterov 1212f8ac4ec9SOleg Nesterov void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) 1213f8ac4ec9SOleg Nesterov { 121461559a81SOleg Nesterov newmm->uprobes_state.xol_area = NULL; 121561559a81SOleg Nesterov 12169f68f672SOleg Nesterov if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { 1217f8ac4ec9SOleg Nesterov set_bit(MMF_HAS_UPROBES, &newmm->flags); 12189f68f672SOleg Nesterov /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ 12199f68f672SOleg Nesterov set_bit(MMF_RECALC_UPROBES, &newmm->flags); 12209f68f672SOleg Nesterov } 1221f8ac4ec9SOleg Nesterov } 1222f8ac4ec9SOleg Nesterov 1223d4b3b638SSrikar Dronamraju /* 1224d4b3b638SSrikar Dronamraju * - search for a free slot. 1225d4b3b638SSrikar Dronamraju */ 1226d4b3b638SSrikar Dronamraju static unsigned long xol_take_insn_slot(struct xol_area *area) 1227d4b3b638SSrikar Dronamraju { 1228d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1229d4b3b638SSrikar Dronamraju int slot_nr; 1230d4b3b638SSrikar Dronamraju 1231d4b3b638SSrikar Dronamraju do { 1232d4b3b638SSrikar Dronamraju slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); 1233d4b3b638SSrikar Dronamraju if (slot_nr < UINSNS_PER_PAGE) { 1234d4b3b638SSrikar Dronamraju if (!test_and_set_bit(slot_nr, area->bitmap)) 1235d4b3b638SSrikar Dronamraju break; 1236d4b3b638SSrikar Dronamraju 1237d4b3b638SSrikar Dronamraju slot_nr = UINSNS_PER_PAGE; 1238d4b3b638SSrikar Dronamraju continue; 1239d4b3b638SSrikar Dronamraju } 1240d4b3b638SSrikar Dronamraju wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); 1241d4b3b638SSrikar Dronamraju } while (slot_nr >= UINSNS_PER_PAGE); 1242d4b3b638SSrikar Dronamraju 1243d4b3b638SSrikar Dronamraju slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); 1244d4b3b638SSrikar Dronamraju atomic_inc(&area->slot_count); 1245d4b3b638SSrikar Dronamraju 1246d4b3b638SSrikar Dronamraju return slot_addr; 1247d4b3b638SSrikar Dronamraju } 1248d4b3b638SSrikar Dronamraju 1249d4b3b638SSrikar Dronamraju /* 1250a6cb3f6dSOleg Nesterov * xol_get_insn_slot - allocate a slot for xol. 1251d4b3b638SSrikar Dronamraju * Returns the allocated slot address or 0. 1252d4b3b638SSrikar Dronamraju */ 1253a6cb3f6dSOleg Nesterov static unsigned long xol_get_insn_slot(struct uprobe *uprobe) 1254d4b3b638SSrikar Dronamraju { 1255d4b3b638SSrikar Dronamraju struct xol_area *area; 1256a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1257d4b3b638SSrikar Dronamraju 12589b545df8SOleg Nesterov area = get_xol_area(); 1259d4b3b638SSrikar Dronamraju if (!area) 1260d4b3b638SSrikar Dronamraju return 0; 1261d4b3b638SSrikar Dronamraju 1262a6cb3f6dSOleg Nesterov xol_vaddr = xol_take_insn_slot(area); 1263a6cb3f6dSOleg Nesterov if (unlikely(!xol_vaddr)) 1264d4b3b638SSrikar Dronamraju return 0; 1265d4b3b638SSrikar Dronamraju 1266a6cb3f6dSOleg Nesterov /* Initialize the slot */ 12678a8de66cSOleg Nesterov copy_to_page(area->page, xol_vaddr, 12688a8de66cSOleg Nesterov uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); 126965b6ecc0SRabin Vincent /* 127065b6ecc0SRabin Vincent * We probably need flush_icache_user_range() but it needs vma. 127165b6ecc0SRabin Vincent * This should work on supported architectures too. 127265b6ecc0SRabin Vincent */ 127365b6ecc0SRabin Vincent flush_dcache_page(area->page); 1274d4b3b638SSrikar Dronamraju 1275a6cb3f6dSOleg Nesterov return xol_vaddr; 1276d4b3b638SSrikar Dronamraju } 1277d4b3b638SSrikar Dronamraju 1278d4b3b638SSrikar Dronamraju /* 1279d4b3b638SSrikar Dronamraju * xol_free_insn_slot - If slot was earlier allocated by 1280d4b3b638SSrikar Dronamraju * @xol_get_insn_slot(), make the slot available for 1281d4b3b638SSrikar Dronamraju * subsequent requests. 1282d4b3b638SSrikar Dronamraju */ 1283d4b3b638SSrikar Dronamraju static void xol_free_insn_slot(struct task_struct *tsk) 1284d4b3b638SSrikar Dronamraju { 1285d4b3b638SSrikar Dronamraju struct xol_area *area; 1286d4b3b638SSrikar Dronamraju unsigned long vma_end; 1287d4b3b638SSrikar Dronamraju unsigned long slot_addr; 1288d4b3b638SSrikar Dronamraju 1289d4b3b638SSrikar Dronamraju if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) 1290d4b3b638SSrikar Dronamraju return; 1291d4b3b638SSrikar Dronamraju 1292d4b3b638SSrikar Dronamraju slot_addr = tsk->utask->xol_vaddr; 1293af4355e9SOleg Nesterov if (unlikely(!slot_addr)) 1294d4b3b638SSrikar Dronamraju return; 1295d4b3b638SSrikar Dronamraju 1296d4b3b638SSrikar Dronamraju area = tsk->mm->uprobes_state.xol_area; 1297d4b3b638SSrikar Dronamraju vma_end = area->vaddr + PAGE_SIZE; 1298d4b3b638SSrikar Dronamraju if (area->vaddr <= slot_addr && slot_addr < vma_end) { 1299d4b3b638SSrikar Dronamraju unsigned long offset; 1300d4b3b638SSrikar Dronamraju int slot_nr; 1301d4b3b638SSrikar Dronamraju 1302d4b3b638SSrikar Dronamraju offset = slot_addr - area->vaddr; 1303d4b3b638SSrikar Dronamraju slot_nr = offset / UPROBE_XOL_SLOT_BYTES; 1304d4b3b638SSrikar Dronamraju if (slot_nr >= UINSNS_PER_PAGE) 1305d4b3b638SSrikar Dronamraju return; 1306d4b3b638SSrikar Dronamraju 1307d4b3b638SSrikar Dronamraju clear_bit(slot_nr, area->bitmap); 1308d4b3b638SSrikar Dronamraju atomic_dec(&area->slot_count); 1309d4b3b638SSrikar Dronamraju if (waitqueue_active(&area->wq)) 1310d4b3b638SSrikar Dronamraju wake_up(&area->wq); 1311d4b3b638SSrikar Dronamraju 1312d4b3b638SSrikar Dronamraju tsk->utask->xol_vaddr = 0; 1313d4b3b638SSrikar Dronamraju } 1314d4b3b638SSrikar Dronamraju } 1315d4b3b638SSrikar Dronamraju 13160326f5a9SSrikar Dronamraju /** 13170326f5a9SSrikar Dronamraju * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs 13180326f5a9SSrikar Dronamraju * @regs: Reflects the saved state of the task after it has hit a breakpoint 13190326f5a9SSrikar Dronamraju * instruction. 13200326f5a9SSrikar Dronamraju * Return the address of the breakpoint instruction. 13210326f5a9SSrikar Dronamraju */ 13220326f5a9SSrikar Dronamraju unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) 13230326f5a9SSrikar Dronamraju { 13240326f5a9SSrikar Dronamraju return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; 13250326f5a9SSrikar Dronamraju } 13260326f5a9SSrikar Dronamraju 13270326f5a9SSrikar Dronamraju /* 13280326f5a9SSrikar Dronamraju * Called with no locks held. 13290326f5a9SSrikar Dronamraju * Called in context of a exiting or a exec-ing thread. 13300326f5a9SSrikar Dronamraju */ 13310326f5a9SSrikar Dronamraju void uprobe_free_utask(struct task_struct *t) 13320326f5a9SSrikar Dronamraju { 13330326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 13340dfd0eb8SAnton Arapov struct return_instance *ri, *tmp; 13350326f5a9SSrikar Dronamraju 13360326f5a9SSrikar Dronamraju if (!utask) 13370326f5a9SSrikar Dronamraju return; 13380326f5a9SSrikar Dronamraju 13390326f5a9SSrikar Dronamraju if (utask->active_uprobe) 13400326f5a9SSrikar Dronamraju put_uprobe(utask->active_uprobe); 13410326f5a9SSrikar Dronamraju 13420dfd0eb8SAnton Arapov ri = utask->return_instances; 13430dfd0eb8SAnton Arapov while (ri) { 13440dfd0eb8SAnton Arapov tmp = ri; 13450dfd0eb8SAnton Arapov ri = ri->next; 13460dfd0eb8SAnton Arapov 13470dfd0eb8SAnton Arapov put_uprobe(tmp->uprobe); 13480dfd0eb8SAnton Arapov kfree(tmp); 13490dfd0eb8SAnton Arapov } 13500dfd0eb8SAnton Arapov 1351d4b3b638SSrikar Dronamraju xol_free_insn_slot(t); 13520326f5a9SSrikar Dronamraju kfree(utask); 13530326f5a9SSrikar Dronamraju t->utask = NULL; 13540326f5a9SSrikar Dronamraju } 13550326f5a9SSrikar Dronamraju 13560326f5a9SSrikar Dronamraju /* 13575a2df662SOleg Nesterov * Allocate a uprobe_task object for the task if if necessary. 13585a2df662SOleg Nesterov * Called when the thread hits a breakpoint. 13590326f5a9SSrikar Dronamraju * 13600326f5a9SSrikar Dronamraju * Returns: 13610326f5a9SSrikar Dronamraju * - pointer to new uprobe_task on success 13620326f5a9SSrikar Dronamraju * - NULL otherwise 13630326f5a9SSrikar Dronamraju */ 13645a2df662SOleg Nesterov static struct uprobe_task *get_utask(void) 13650326f5a9SSrikar Dronamraju { 13665a2df662SOleg Nesterov if (!current->utask) 13675a2df662SOleg Nesterov current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 13685a2df662SOleg Nesterov return current->utask; 13690326f5a9SSrikar Dronamraju } 13700326f5a9SSrikar Dronamraju 1371248d3a7bSOleg Nesterov static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) 1372248d3a7bSOleg Nesterov { 1373248d3a7bSOleg Nesterov struct uprobe_task *n_utask; 1374248d3a7bSOleg Nesterov struct return_instance **p, *o, *n; 1375248d3a7bSOleg Nesterov 1376248d3a7bSOleg Nesterov n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); 1377248d3a7bSOleg Nesterov if (!n_utask) 1378248d3a7bSOleg Nesterov return -ENOMEM; 1379248d3a7bSOleg Nesterov t->utask = n_utask; 1380248d3a7bSOleg Nesterov 1381248d3a7bSOleg Nesterov p = &n_utask->return_instances; 1382248d3a7bSOleg Nesterov for (o = o_utask->return_instances; o; o = o->next) { 1383248d3a7bSOleg Nesterov n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); 1384248d3a7bSOleg Nesterov if (!n) 1385248d3a7bSOleg Nesterov return -ENOMEM; 1386248d3a7bSOleg Nesterov 1387248d3a7bSOleg Nesterov *n = *o; 1388248d3a7bSOleg Nesterov atomic_inc(&n->uprobe->ref); 1389248d3a7bSOleg Nesterov n->next = NULL; 1390248d3a7bSOleg Nesterov 1391248d3a7bSOleg Nesterov *p = n; 1392248d3a7bSOleg Nesterov p = &n->next; 1393248d3a7bSOleg Nesterov n_utask->depth++; 1394248d3a7bSOleg Nesterov } 1395248d3a7bSOleg Nesterov 1396248d3a7bSOleg Nesterov return 0; 1397248d3a7bSOleg Nesterov } 1398248d3a7bSOleg Nesterov 1399248d3a7bSOleg Nesterov static void uprobe_warn(struct task_struct *t, const char *msg) 1400248d3a7bSOleg Nesterov { 1401248d3a7bSOleg Nesterov pr_warn("uprobe: %s:%d failed to %s\n", 1402248d3a7bSOleg Nesterov current->comm, current->pid, msg); 1403248d3a7bSOleg Nesterov } 1404248d3a7bSOleg Nesterov 1405aa59c53fSOleg Nesterov static void dup_xol_work(struct callback_head *work) 1406aa59c53fSOleg Nesterov { 1407aa59c53fSOleg Nesterov kfree(work); 1408aa59c53fSOleg Nesterov 1409aa59c53fSOleg Nesterov if (current->flags & PF_EXITING) 1410aa59c53fSOleg Nesterov return; 1411aa59c53fSOleg Nesterov 1412aa59c53fSOleg Nesterov if (!__create_xol_area(current->utask->vaddr)) 1413aa59c53fSOleg Nesterov uprobe_warn(current, "dup xol area"); 1414aa59c53fSOleg Nesterov } 1415aa59c53fSOleg Nesterov 1416e78aebfdSAnton Arapov /* 1417b68e0749SOleg Nesterov * Called in context of a new clone/fork from copy_process. 1418b68e0749SOleg Nesterov */ 14193ab67966SOleg Nesterov void uprobe_copy_process(struct task_struct *t, unsigned long flags) 1420b68e0749SOleg Nesterov { 1421248d3a7bSOleg Nesterov struct uprobe_task *utask = current->utask; 1422248d3a7bSOleg Nesterov struct mm_struct *mm = current->mm; 1423aa59c53fSOleg Nesterov struct callback_head *work; 1424aa59c53fSOleg Nesterov struct xol_area *area; 1425248d3a7bSOleg Nesterov 1426b68e0749SOleg Nesterov t->utask = NULL; 1427248d3a7bSOleg Nesterov 14283ab67966SOleg Nesterov if (!utask || !utask->return_instances) 14293ab67966SOleg Nesterov return; 14303ab67966SOleg Nesterov 14313ab67966SOleg Nesterov if (mm == t->mm && !(flags & CLONE_VFORK)) 1432248d3a7bSOleg Nesterov return; 1433248d3a7bSOleg Nesterov 1434248d3a7bSOleg Nesterov if (dup_utask(t, utask)) 1435248d3a7bSOleg Nesterov return uprobe_warn(t, "dup ret instances"); 1436aa59c53fSOleg Nesterov 1437aa59c53fSOleg Nesterov /* The task can fork() after dup_xol_work() fails */ 1438aa59c53fSOleg Nesterov area = mm->uprobes_state.xol_area; 1439aa59c53fSOleg Nesterov if (!area) 1440aa59c53fSOleg Nesterov return uprobe_warn(t, "dup xol area"); 1441aa59c53fSOleg Nesterov 14423ab67966SOleg Nesterov if (mm == t->mm) 14433ab67966SOleg Nesterov return; 14443ab67966SOleg Nesterov 1445aa59c53fSOleg Nesterov /* TODO: move it into the union in uprobe_task */ 1446aa59c53fSOleg Nesterov work = kmalloc(sizeof(*work), GFP_KERNEL); 1447aa59c53fSOleg Nesterov if (!work) 1448aa59c53fSOleg Nesterov return uprobe_warn(t, "dup xol area"); 1449aa59c53fSOleg Nesterov 1450aa59c53fSOleg Nesterov utask->vaddr = area->vaddr; 1451aa59c53fSOleg Nesterov init_task_work(work, dup_xol_work); 1452aa59c53fSOleg Nesterov task_work_add(t, work, true); 1453b68e0749SOleg Nesterov } 1454b68e0749SOleg Nesterov 1455b68e0749SOleg Nesterov /* 1456e78aebfdSAnton Arapov * Current area->vaddr notion assume the trampoline address is always 1457e78aebfdSAnton Arapov * equal area->vaddr. 1458e78aebfdSAnton Arapov * 1459e78aebfdSAnton Arapov * Returns -1 in case the xol_area is not allocated. 1460e78aebfdSAnton Arapov */ 1461e78aebfdSAnton Arapov static unsigned long get_trampoline_vaddr(void) 1462e78aebfdSAnton Arapov { 1463e78aebfdSAnton Arapov struct xol_area *area; 1464e78aebfdSAnton Arapov unsigned long trampoline_vaddr = -1; 1465e78aebfdSAnton Arapov 1466e78aebfdSAnton Arapov area = current->mm->uprobes_state.xol_area; 1467e78aebfdSAnton Arapov smp_read_barrier_depends(); 1468e78aebfdSAnton Arapov if (area) 1469e78aebfdSAnton Arapov trampoline_vaddr = area->vaddr; 1470e78aebfdSAnton Arapov 1471e78aebfdSAnton Arapov return trampoline_vaddr; 1472e78aebfdSAnton Arapov } 1473e78aebfdSAnton Arapov 14740dfd0eb8SAnton Arapov static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) 14750dfd0eb8SAnton Arapov { 14760dfd0eb8SAnton Arapov struct return_instance *ri; 14770dfd0eb8SAnton Arapov struct uprobe_task *utask; 14780dfd0eb8SAnton Arapov unsigned long orig_ret_vaddr, trampoline_vaddr; 14790dfd0eb8SAnton Arapov bool chained = false; 14800dfd0eb8SAnton Arapov 14810dfd0eb8SAnton Arapov if (!get_xol_area()) 14820dfd0eb8SAnton Arapov return; 14830dfd0eb8SAnton Arapov 14840dfd0eb8SAnton Arapov utask = get_utask(); 14850dfd0eb8SAnton Arapov if (!utask) 14860dfd0eb8SAnton Arapov return; 14870dfd0eb8SAnton Arapov 1488ded49c55SAnton Arapov if (utask->depth >= MAX_URETPROBE_DEPTH) { 1489ded49c55SAnton Arapov printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" 1490ded49c55SAnton Arapov " nestedness limit pid/tgid=%d/%d\n", 1491ded49c55SAnton Arapov current->pid, current->tgid); 1492ded49c55SAnton Arapov return; 1493ded49c55SAnton Arapov } 1494ded49c55SAnton Arapov 14950dfd0eb8SAnton Arapov ri = kzalloc(sizeof(struct return_instance), GFP_KERNEL); 14960dfd0eb8SAnton Arapov if (!ri) 14970dfd0eb8SAnton Arapov goto fail; 14980dfd0eb8SAnton Arapov 14990dfd0eb8SAnton Arapov trampoline_vaddr = get_trampoline_vaddr(); 15000dfd0eb8SAnton Arapov orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); 15010dfd0eb8SAnton Arapov if (orig_ret_vaddr == -1) 15020dfd0eb8SAnton Arapov goto fail; 15030dfd0eb8SAnton Arapov 15040dfd0eb8SAnton Arapov /* 15050dfd0eb8SAnton Arapov * We don't want to keep trampoline address in stack, rather keep the 15060dfd0eb8SAnton Arapov * original return address of first caller thru all the consequent 15070dfd0eb8SAnton Arapov * instances. This also makes breakpoint unwrapping easier. 15080dfd0eb8SAnton Arapov */ 15090dfd0eb8SAnton Arapov if (orig_ret_vaddr == trampoline_vaddr) { 15100dfd0eb8SAnton Arapov if (!utask->return_instances) { 15110dfd0eb8SAnton Arapov /* 15120dfd0eb8SAnton Arapov * This situation is not possible. Likely we have an 15130dfd0eb8SAnton Arapov * attack from user-space. 15140dfd0eb8SAnton Arapov */ 15150dfd0eb8SAnton Arapov pr_warn("uprobe: unable to set uretprobe pid/tgid=%d/%d\n", 15160dfd0eb8SAnton Arapov current->pid, current->tgid); 15170dfd0eb8SAnton Arapov goto fail; 15180dfd0eb8SAnton Arapov } 15190dfd0eb8SAnton Arapov 15200dfd0eb8SAnton Arapov chained = true; 15210dfd0eb8SAnton Arapov orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; 15220dfd0eb8SAnton Arapov } 15230dfd0eb8SAnton Arapov 15240dfd0eb8SAnton Arapov atomic_inc(&uprobe->ref); 15250dfd0eb8SAnton Arapov ri->uprobe = uprobe; 15260dfd0eb8SAnton Arapov ri->func = instruction_pointer(regs); 15270dfd0eb8SAnton Arapov ri->orig_ret_vaddr = orig_ret_vaddr; 15280dfd0eb8SAnton Arapov ri->chained = chained; 15290dfd0eb8SAnton Arapov 1530ded49c55SAnton Arapov utask->depth++; 1531ded49c55SAnton Arapov 15320dfd0eb8SAnton Arapov /* add instance to the stack */ 15330dfd0eb8SAnton Arapov ri->next = utask->return_instances; 15340dfd0eb8SAnton Arapov utask->return_instances = ri; 15350dfd0eb8SAnton Arapov 15360dfd0eb8SAnton Arapov return; 15370dfd0eb8SAnton Arapov 15380dfd0eb8SAnton Arapov fail: 15390dfd0eb8SAnton Arapov kfree(ri); 15400dfd0eb8SAnton Arapov } 15410dfd0eb8SAnton Arapov 15420326f5a9SSrikar Dronamraju /* Prepare to single-step probed instruction out of line. */ 15430326f5a9SSrikar Dronamraju static int 1544a6cb3f6dSOleg Nesterov pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) 15450326f5a9SSrikar Dronamraju { 1546a6cb3f6dSOleg Nesterov struct uprobe_task *utask; 1547a6cb3f6dSOleg Nesterov unsigned long xol_vaddr; 1548aba51024SOleg Nesterov int err; 1549d4b3b638SSrikar Dronamraju 1550608e7427SOleg Nesterov utask = get_utask(); 1551608e7427SOleg Nesterov if (!utask) 1552608e7427SOleg Nesterov return -ENOMEM; 1553a6cb3f6dSOleg Nesterov 1554a6cb3f6dSOleg Nesterov xol_vaddr = xol_get_insn_slot(uprobe); 1555a6cb3f6dSOleg Nesterov if (!xol_vaddr) 1556a6cb3f6dSOleg Nesterov return -ENOMEM; 1557a6cb3f6dSOleg Nesterov 1558a6cb3f6dSOleg Nesterov utask->xol_vaddr = xol_vaddr; 1559a6cb3f6dSOleg Nesterov utask->vaddr = bp_vaddr; 1560a6cb3f6dSOleg Nesterov 1561aba51024SOleg Nesterov err = arch_uprobe_pre_xol(&uprobe->arch, regs); 1562aba51024SOleg Nesterov if (unlikely(err)) { 1563aba51024SOleg Nesterov xol_free_insn_slot(current); 1564aba51024SOleg Nesterov return err; 1565aba51024SOleg Nesterov } 1566aba51024SOleg Nesterov 1567608e7427SOleg Nesterov utask->active_uprobe = uprobe; 1568608e7427SOleg Nesterov utask->state = UTASK_SSTEP; 1569aba51024SOleg Nesterov return 0; 15700326f5a9SSrikar Dronamraju } 15710326f5a9SSrikar Dronamraju 15720326f5a9SSrikar Dronamraju /* 15730326f5a9SSrikar Dronamraju * If we are singlestepping, then ensure this thread is not connected to 15740326f5a9SSrikar Dronamraju * non-fatal signals until completion of singlestep. When xol insn itself 15750326f5a9SSrikar Dronamraju * triggers the signal, restart the original insn even if the task is 15760326f5a9SSrikar Dronamraju * already SIGKILL'ed (since coredump should report the correct ip). This 15770326f5a9SSrikar Dronamraju * is even more important if the task has a handler for SIGSEGV/etc, The 15780326f5a9SSrikar Dronamraju * _same_ instruction should be repeated again after return from the signal 15790326f5a9SSrikar Dronamraju * handler, and SSTEP can never finish in this case. 15800326f5a9SSrikar Dronamraju */ 15810326f5a9SSrikar Dronamraju bool uprobe_deny_signal(void) 15820326f5a9SSrikar Dronamraju { 15830326f5a9SSrikar Dronamraju struct task_struct *t = current; 15840326f5a9SSrikar Dronamraju struct uprobe_task *utask = t->utask; 15850326f5a9SSrikar Dronamraju 15860326f5a9SSrikar Dronamraju if (likely(!utask || !utask->active_uprobe)) 15870326f5a9SSrikar Dronamraju return false; 15880326f5a9SSrikar Dronamraju 15890326f5a9SSrikar Dronamraju WARN_ON_ONCE(utask->state != UTASK_SSTEP); 15900326f5a9SSrikar Dronamraju 15910326f5a9SSrikar Dronamraju if (signal_pending(t)) { 15920326f5a9SSrikar Dronamraju spin_lock_irq(&t->sighand->siglock); 15930326f5a9SSrikar Dronamraju clear_tsk_thread_flag(t, TIF_SIGPENDING); 15940326f5a9SSrikar Dronamraju spin_unlock_irq(&t->sighand->siglock); 15950326f5a9SSrikar Dronamraju 15960326f5a9SSrikar Dronamraju if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { 15970326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_TRAPPED; 15980326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_UPROBE); 15990326f5a9SSrikar Dronamraju set_tsk_thread_flag(t, TIF_NOTIFY_RESUME); 16000326f5a9SSrikar Dronamraju } 16010326f5a9SSrikar Dronamraju } 16020326f5a9SSrikar Dronamraju 16030326f5a9SSrikar Dronamraju return true; 16040326f5a9SSrikar Dronamraju } 16050326f5a9SSrikar Dronamraju 16060326f5a9SSrikar Dronamraju /* 16070326f5a9SSrikar Dronamraju * Avoid singlestepping the original instruction if the original instruction 16080326f5a9SSrikar Dronamraju * is a NOP or can be emulated. 16090326f5a9SSrikar Dronamraju */ 16100326f5a9SSrikar Dronamraju static bool can_skip_sstep(struct uprobe *uprobe, struct pt_regs *regs) 16110326f5a9SSrikar Dronamraju { 161271434f2fSOleg Nesterov if (test_bit(UPROBE_SKIP_SSTEP, &uprobe->flags)) { 16130326f5a9SSrikar Dronamraju if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) 16140326f5a9SSrikar Dronamraju return true; 161571434f2fSOleg Nesterov clear_bit(UPROBE_SKIP_SSTEP, &uprobe->flags); 16160578a970SOleg Nesterov } 16170326f5a9SSrikar Dronamraju return false; 16180326f5a9SSrikar Dronamraju } 16190326f5a9SSrikar Dronamraju 1620499a4f3eSOleg Nesterov static void mmf_recalc_uprobes(struct mm_struct *mm) 1621499a4f3eSOleg Nesterov { 1622499a4f3eSOleg Nesterov struct vm_area_struct *vma; 1623499a4f3eSOleg Nesterov 1624499a4f3eSOleg Nesterov for (vma = mm->mmap; vma; vma = vma->vm_next) { 1625499a4f3eSOleg Nesterov if (!valid_vma(vma, false)) 1626499a4f3eSOleg Nesterov continue; 1627499a4f3eSOleg Nesterov /* 1628499a4f3eSOleg Nesterov * This is not strictly accurate, we can race with 1629499a4f3eSOleg Nesterov * uprobe_unregister() and see the already removed 1630499a4f3eSOleg Nesterov * uprobe if delete_uprobe() was not yet called. 163163633cbfSOleg Nesterov * Or this uprobe can be filtered out. 1632499a4f3eSOleg Nesterov */ 1633499a4f3eSOleg Nesterov if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) 1634499a4f3eSOleg Nesterov return; 1635499a4f3eSOleg Nesterov } 1636499a4f3eSOleg Nesterov 1637499a4f3eSOleg Nesterov clear_bit(MMF_HAS_UPROBES, &mm->flags); 1638499a4f3eSOleg Nesterov } 1639499a4f3eSOleg Nesterov 16400908ad6eSAnanth N Mavinakayanahalli static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) 1641ec75fba9SOleg Nesterov { 1642ec75fba9SOleg Nesterov struct page *page; 1643ec75fba9SOleg Nesterov uprobe_opcode_t opcode; 1644ec75fba9SOleg Nesterov int result; 1645ec75fba9SOleg Nesterov 1646ec75fba9SOleg Nesterov pagefault_disable(); 1647ec75fba9SOleg Nesterov result = __copy_from_user_inatomic(&opcode, (void __user*)vaddr, 1648ec75fba9SOleg Nesterov sizeof(opcode)); 1649ec75fba9SOleg Nesterov pagefault_enable(); 1650ec75fba9SOleg Nesterov 1651ec75fba9SOleg Nesterov if (likely(result == 0)) 1652ec75fba9SOleg Nesterov goto out; 1653ec75fba9SOleg Nesterov 1654ec75fba9SOleg Nesterov result = get_user_pages(NULL, mm, vaddr, 1, 0, 1, &page, NULL); 1655ec75fba9SOleg Nesterov if (result < 0) 1656ec75fba9SOleg Nesterov return result; 1657ec75fba9SOleg Nesterov 1658ab0d805cSOleg Nesterov copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); 1659ec75fba9SOleg Nesterov put_page(page); 1660ec75fba9SOleg Nesterov out: 16610908ad6eSAnanth N Mavinakayanahalli /* This needs to return true for any variant of the trap insn */ 16620908ad6eSAnanth N Mavinakayanahalli return is_trap_insn(&opcode); 1663ec75fba9SOleg Nesterov } 1664ec75fba9SOleg Nesterov 1665d790d346SOleg Nesterov static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) 16660326f5a9SSrikar Dronamraju { 16673a9ea052SOleg Nesterov struct mm_struct *mm = current->mm; 16683a9ea052SOleg Nesterov struct uprobe *uprobe = NULL; 16690326f5a9SSrikar Dronamraju struct vm_area_struct *vma; 16700326f5a9SSrikar Dronamraju 16710326f5a9SSrikar Dronamraju down_read(&mm->mmap_sem); 16720326f5a9SSrikar Dronamraju vma = find_vma(mm, bp_vaddr); 16733a9ea052SOleg Nesterov if (vma && vma->vm_start <= bp_vaddr) { 16743a9ea052SOleg Nesterov if (valid_vma(vma, false)) { 1675f281769eSOleg Nesterov struct inode *inode = file_inode(vma->vm_file); 1676cb113b47SOleg Nesterov loff_t offset = vaddr_to_offset(vma, bp_vaddr); 16770326f5a9SSrikar Dronamraju 16780326f5a9SSrikar Dronamraju uprobe = find_uprobe(inode, offset); 16790326f5a9SSrikar Dronamraju } 1680d790d346SOleg Nesterov 1681d790d346SOleg Nesterov if (!uprobe) 16820908ad6eSAnanth N Mavinakayanahalli *is_swbp = is_trap_at_addr(mm, bp_vaddr); 1683d790d346SOleg Nesterov } else { 1684d790d346SOleg Nesterov *is_swbp = -EFAULT; 16853a9ea052SOleg Nesterov } 1686499a4f3eSOleg Nesterov 1687499a4f3eSOleg Nesterov if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) 1688499a4f3eSOleg Nesterov mmf_recalc_uprobes(mm); 16890326f5a9SSrikar Dronamraju up_read(&mm->mmap_sem); 16900326f5a9SSrikar Dronamraju 16913a9ea052SOleg Nesterov return uprobe; 16923a9ea052SOleg Nesterov } 16933a9ea052SOleg Nesterov 1694da1816b1SOleg Nesterov static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) 1695da1816b1SOleg Nesterov { 1696da1816b1SOleg Nesterov struct uprobe_consumer *uc; 1697da1816b1SOleg Nesterov int remove = UPROBE_HANDLER_REMOVE; 16980dfd0eb8SAnton Arapov bool need_prep = false; /* prepare return uprobe, when needed */ 1699da1816b1SOleg Nesterov 1700da1816b1SOleg Nesterov down_read(&uprobe->register_rwsem); 1701da1816b1SOleg Nesterov for (uc = uprobe->consumers; uc; uc = uc->next) { 1702ea024870SAnton Arapov int rc = 0; 1703da1816b1SOleg Nesterov 1704ea024870SAnton Arapov if (uc->handler) { 1705ea024870SAnton Arapov rc = uc->handler(uc, regs); 1706da1816b1SOleg Nesterov WARN(rc & ~UPROBE_HANDLER_MASK, 1707da1816b1SOleg Nesterov "bad rc=0x%x from %pf()\n", rc, uc->handler); 1708ea024870SAnton Arapov } 17090dfd0eb8SAnton Arapov 17100dfd0eb8SAnton Arapov if (uc->ret_handler) 17110dfd0eb8SAnton Arapov need_prep = true; 17120dfd0eb8SAnton Arapov 1713da1816b1SOleg Nesterov remove &= rc; 1714da1816b1SOleg Nesterov } 1715da1816b1SOleg Nesterov 17160dfd0eb8SAnton Arapov if (need_prep && !remove) 17170dfd0eb8SAnton Arapov prepare_uretprobe(uprobe, regs); /* put bp at return */ 17180dfd0eb8SAnton Arapov 1719da1816b1SOleg Nesterov if (remove && uprobe->consumers) { 1720da1816b1SOleg Nesterov WARN_ON(!uprobe_is_active(uprobe)); 1721da1816b1SOleg Nesterov unapply_uprobe(uprobe, current->mm); 1722da1816b1SOleg Nesterov } 1723da1816b1SOleg Nesterov up_read(&uprobe->register_rwsem); 1724da1816b1SOleg Nesterov } 1725da1816b1SOleg Nesterov 1726fec8898dSAnton Arapov static void 1727fec8898dSAnton Arapov handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) 1728fec8898dSAnton Arapov { 1729fec8898dSAnton Arapov struct uprobe *uprobe = ri->uprobe; 1730fec8898dSAnton Arapov struct uprobe_consumer *uc; 1731fec8898dSAnton Arapov 1732fec8898dSAnton Arapov down_read(&uprobe->register_rwsem); 1733fec8898dSAnton Arapov for (uc = uprobe->consumers; uc; uc = uc->next) { 1734fec8898dSAnton Arapov if (uc->ret_handler) 1735fec8898dSAnton Arapov uc->ret_handler(uc, ri->func, regs); 1736fec8898dSAnton Arapov } 1737fec8898dSAnton Arapov up_read(&uprobe->register_rwsem); 1738fec8898dSAnton Arapov } 1739fec8898dSAnton Arapov 1740fec8898dSAnton Arapov static bool handle_trampoline(struct pt_regs *regs) 1741fec8898dSAnton Arapov { 1742fec8898dSAnton Arapov struct uprobe_task *utask; 1743fec8898dSAnton Arapov struct return_instance *ri, *tmp; 1744fec8898dSAnton Arapov bool chained; 1745fec8898dSAnton Arapov 1746fec8898dSAnton Arapov utask = current->utask; 1747fec8898dSAnton Arapov if (!utask) 1748fec8898dSAnton Arapov return false; 1749fec8898dSAnton Arapov 1750fec8898dSAnton Arapov ri = utask->return_instances; 1751fec8898dSAnton Arapov if (!ri) 1752fec8898dSAnton Arapov return false; 1753fec8898dSAnton Arapov 1754fec8898dSAnton Arapov /* 1755fec8898dSAnton Arapov * TODO: we should throw out return_instance's invalidated by 1756fec8898dSAnton Arapov * longjmp(), currently we assume that the probed function always 1757fec8898dSAnton Arapov * returns. 1758fec8898dSAnton Arapov */ 1759fec8898dSAnton Arapov instruction_pointer_set(regs, ri->orig_ret_vaddr); 1760fec8898dSAnton Arapov 1761fec8898dSAnton Arapov for (;;) { 1762fec8898dSAnton Arapov handle_uretprobe_chain(ri, regs); 1763fec8898dSAnton Arapov 1764fec8898dSAnton Arapov chained = ri->chained; 1765fec8898dSAnton Arapov put_uprobe(ri->uprobe); 1766fec8898dSAnton Arapov 1767fec8898dSAnton Arapov tmp = ri; 1768fec8898dSAnton Arapov ri = ri->next; 1769fec8898dSAnton Arapov kfree(tmp); 1770878b5a6eSOleg Nesterov utask->depth--; 1771fec8898dSAnton Arapov 1772fec8898dSAnton Arapov if (!chained) 1773fec8898dSAnton Arapov break; 1774fec8898dSAnton Arapov BUG_ON(!ri); 1775fec8898dSAnton Arapov } 1776fec8898dSAnton Arapov 1777fec8898dSAnton Arapov utask->return_instances = ri; 1778fec8898dSAnton Arapov 1779fec8898dSAnton Arapov return true; 1780fec8898dSAnton Arapov } 1781fec8898dSAnton Arapov 17823a9ea052SOleg Nesterov /* 17833a9ea052SOleg Nesterov * Run handler and ask thread to singlestep. 17843a9ea052SOleg Nesterov * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. 17853a9ea052SOleg Nesterov */ 17863a9ea052SOleg Nesterov static void handle_swbp(struct pt_regs *regs) 17873a9ea052SOleg Nesterov { 17883a9ea052SOleg Nesterov struct uprobe *uprobe; 17893a9ea052SOleg Nesterov unsigned long bp_vaddr; 179056bb4cf6SOleg Nesterov int uninitialized_var(is_swbp); 17913a9ea052SOleg Nesterov 17923a9ea052SOleg Nesterov bp_vaddr = uprobe_get_swbp_addr(regs); 1793fec8898dSAnton Arapov if (bp_vaddr == get_trampoline_vaddr()) { 1794fec8898dSAnton Arapov if (handle_trampoline(regs)) 1795fec8898dSAnton Arapov return; 17963a9ea052SOleg Nesterov 1797fec8898dSAnton Arapov pr_warn("uprobe: unable to handle uretprobe pid/tgid=%d/%d\n", 1798fec8898dSAnton Arapov current->pid, current->tgid); 1799fec8898dSAnton Arapov } 1800fec8898dSAnton Arapov 1801fec8898dSAnton Arapov uprobe = find_active_uprobe(bp_vaddr, &is_swbp); 18020326f5a9SSrikar Dronamraju if (!uprobe) { 180356bb4cf6SOleg Nesterov if (is_swbp > 0) { 18040326f5a9SSrikar Dronamraju /* No matching uprobe; signal SIGTRAP. */ 18050326f5a9SSrikar Dronamraju send_sig(SIGTRAP, current, 0); 180656bb4cf6SOleg Nesterov } else { 180756bb4cf6SOleg Nesterov /* 180856bb4cf6SOleg Nesterov * Either we raced with uprobe_unregister() or we can't 180956bb4cf6SOleg Nesterov * access this memory. The latter is only possible if 181056bb4cf6SOleg Nesterov * another thread plays with our ->mm. In both cases 181156bb4cf6SOleg Nesterov * we can simply restart. If this vma was unmapped we 181256bb4cf6SOleg Nesterov * can pretend this insn was not executed yet and get 181356bb4cf6SOleg Nesterov * the (correct) SIGSEGV after restart. 181456bb4cf6SOleg Nesterov */ 181556bb4cf6SOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 181656bb4cf6SOleg Nesterov } 18170326f5a9SSrikar Dronamraju return; 18180326f5a9SSrikar Dronamraju } 181974e59dfcSOleg Nesterov 182074e59dfcSOleg Nesterov /* change it in advance for ->handler() and restart */ 182174e59dfcSOleg Nesterov instruction_pointer_set(regs, bp_vaddr); 182274e59dfcSOleg Nesterov 1823142b18ddSOleg Nesterov /* 1824142b18ddSOleg Nesterov * TODO: move copy_insn/etc into _register and remove this hack. 1825142b18ddSOleg Nesterov * After we hit the bp, _unregister + _register can install the 1826142b18ddSOleg Nesterov * new and not-yet-analyzed uprobe at the same address, restart. 1827142b18ddSOleg Nesterov */ 1828142b18ddSOleg Nesterov smp_rmb(); /* pairs with wmb() in install_breakpoint() */ 182971434f2fSOleg Nesterov if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) 183074e59dfcSOleg Nesterov goto out; 18310326f5a9SSrikar Dronamraju 18320326f5a9SSrikar Dronamraju handler_chain(uprobe, regs); 18330578a970SOleg Nesterov if (can_skip_sstep(uprobe, regs)) 18340578a970SOleg Nesterov goto out; 18350326f5a9SSrikar Dronamraju 1836608e7427SOleg Nesterov if (!pre_ssout(uprobe, regs, bp_vaddr)) 18370326f5a9SSrikar Dronamraju return; 18380326f5a9SSrikar Dronamraju 183974e59dfcSOleg Nesterov /* can_skip_sstep() succeeded, or restart if can't singlestep */ 18400578a970SOleg Nesterov out: 18410326f5a9SSrikar Dronamraju put_uprobe(uprobe); 18420326f5a9SSrikar Dronamraju } 18430326f5a9SSrikar Dronamraju 18440326f5a9SSrikar Dronamraju /* 18450326f5a9SSrikar Dronamraju * Perform required fix-ups and disable singlestep. 18460326f5a9SSrikar Dronamraju * Allow pending signals to take effect. 18470326f5a9SSrikar Dronamraju */ 18480326f5a9SSrikar Dronamraju static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) 18490326f5a9SSrikar Dronamraju { 18500326f5a9SSrikar Dronamraju struct uprobe *uprobe; 18510326f5a9SSrikar Dronamraju 18520326f5a9SSrikar Dronamraju uprobe = utask->active_uprobe; 18530326f5a9SSrikar Dronamraju if (utask->state == UTASK_SSTEP_ACK) 18540326f5a9SSrikar Dronamraju arch_uprobe_post_xol(&uprobe->arch, regs); 18550326f5a9SSrikar Dronamraju else if (utask->state == UTASK_SSTEP_TRAPPED) 18560326f5a9SSrikar Dronamraju arch_uprobe_abort_xol(&uprobe->arch, regs); 18570326f5a9SSrikar Dronamraju else 18580326f5a9SSrikar Dronamraju WARN_ON_ONCE(1); 18590326f5a9SSrikar Dronamraju 18600326f5a9SSrikar Dronamraju put_uprobe(uprobe); 18610326f5a9SSrikar Dronamraju utask->active_uprobe = NULL; 18620326f5a9SSrikar Dronamraju utask->state = UTASK_RUNNING; 1863d4b3b638SSrikar Dronamraju xol_free_insn_slot(current); 18640326f5a9SSrikar Dronamraju 18650326f5a9SSrikar Dronamraju spin_lock_irq(¤t->sighand->siglock); 18660326f5a9SSrikar Dronamraju recalc_sigpending(); /* see uprobe_deny_signal() */ 18670326f5a9SSrikar Dronamraju spin_unlock_irq(¤t->sighand->siglock); 18680326f5a9SSrikar Dronamraju } 18690326f5a9SSrikar Dronamraju 18700326f5a9SSrikar Dronamraju /* 18711b08e907SOleg Nesterov * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and 18721b08e907SOleg Nesterov * allows the thread to return from interrupt. After that handle_swbp() 18731b08e907SOleg Nesterov * sets utask->active_uprobe. 18740326f5a9SSrikar Dronamraju * 18751b08e907SOleg Nesterov * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag 18761b08e907SOleg Nesterov * and allows the thread to return from interrupt. 18770326f5a9SSrikar Dronamraju * 18780326f5a9SSrikar Dronamraju * While returning to userspace, thread notices the TIF_UPROBE flag and calls 18790326f5a9SSrikar Dronamraju * uprobe_notify_resume(). 18800326f5a9SSrikar Dronamraju */ 18810326f5a9SSrikar Dronamraju void uprobe_notify_resume(struct pt_regs *regs) 18820326f5a9SSrikar Dronamraju { 18830326f5a9SSrikar Dronamraju struct uprobe_task *utask; 18840326f5a9SSrikar Dronamraju 1885db023ea5SOleg Nesterov clear_thread_flag(TIF_UPROBE); 1886db023ea5SOleg Nesterov 18870326f5a9SSrikar Dronamraju utask = current->utask; 18881b08e907SOleg Nesterov if (utask && utask->active_uprobe) 18890326f5a9SSrikar Dronamraju handle_singlestep(utask, regs); 18901b08e907SOleg Nesterov else 18911b08e907SOleg Nesterov handle_swbp(regs); 18920326f5a9SSrikar Dronamraju } 18930326f5a9SSrikar Dronamraju 18940326f5a9SSrikar Dronamraju /* 18950326f5a9SSrikar Dronamraju * uprobe_pre_sstep_notifier gets called from interrupt context as part of 18960326f5a9SSrikar Dronamraju * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. 18970326f5a9SSrikar Dronamraju */ 18980326f5a9SSrikar Dronamraju int uprobe_pre_sstep_notifier(struct pt_regs *regs) 18990326f5a9SSrikar Dronamraju { 19000dfd0eb8SAnton Arapov if (!current->mm) 19010dfd0eb8SAnton Arapov return 0; 19020dfd0eb8SAnton Arapov 19030dfd0eb8SAnton Arapov if (!test_bit(MMF_HAS_UPROBES, ¤t->mm->flags) && 19040dfd0eb8SAnton Arapov (!current->utask || !current->utask->return_instances)) 19050326f5a9SSrikar Dronamraju return 0; 19060326f5a9SSrikar Dronamraju 19070326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 19080326f5a9SSrikar Dronamraju return 1; 19090326f5a9SSrikar Dronamraju } 19100326f5a9SSrikar Dronamraju 19110326f5a9SSrikar Dronamraju /* 19120326f5a9SSrikar Dronamraju * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier 19130326f5a9SSrikar Dronamraju * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. 19140326f5a9SSrikar Dronamraju */ 19150326f5a9SSrikar Dronamraju int uprobe_post_sstep_notifier(struct pt_regs *regs) 19160326f5a9SSrikar Dronamraju { 19170326f5a9SSrikar Dronamraju struct uprobe_task *utask = current->utask; 19180326f5a9SSrikar Dronamraju 19190326f5a9SSrikar Dronamraju if (!current->mm || !utask || !utask->active_uprobe) 19200326f5a9SSrikar Dronamraju /* task is currently not uprobed */ 19210326f5a9SSrikar Dronamraju return 0; 19220326f5a9SSrikar Dronamraju 19230326f5a9SSrikar Dronamraju utask->state = UTASK_SSTEP_ACK; 19240326f5a9SSrikar Dronamraju set_thread_flag(TIF_UPROBE); 19250326f5a9SSrikar Dronamraju return 1; 19260326f5a9SSrikar Dronamraju } 19270326f5a9SSrikar Dronamraju 19280326f5a9SSrikar Dronamraju static struct notifier_block uprobe_exception_nb = { 19290326f5a9SSrikar Dronamraju .notifier_call = arch_uprobe_exception_notify, 19300326f5a9SSrikar Dronamraju .priority = INT_MAX-1, /* notified after kprobes, kgdb */ 19310326f5a9SSrikar Dronamraju }; 19320326f5a9SSrikar Dronamraju 1933a5f4374aSIngo Molnar static int __init init_uprobes(void) 1934a5f4374aSIngo Molnar { 1935a5f4374aSIngo Molnar int i; 1936a5f4374aSIngo Molnar 193766d06dffSOleg Nesterov for (i = 0; i < UPROBES_HASH_SZ; i++) 1938a5f4374aSIngo Molnar mutex_init(&uprobes_mmap_mutex[i]); 19390326f5a9SSrikar Dronamraju 194032cdba1eSOleg Nesterov if (percpu_init_rwsem(&dup_mmap_sem)) 194132cdba1eSOleg Nesterov return -ENOMEM; 194232cdba1eSOleg Nesterov 19430326f5a9SSrikar Dronamraju return register_die_notifier(&uprobe_exception_nb); 1944a5f4374aSIngo Molnar } 1945736e89d9SOleg Nesterov __initcall(init_uprobes); 1946