cregit-Linux how code gets into the kernel

Release 4.15 kernel/events/uprobes.c

Directory: kernel/events
/*
 * User-space Probes (UProbes)
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2008-2012
 * Authors:
 *      Srikar Dronamraju
 *      Jim Keniston
 * Copyright (C) 2011-2012 Red Hat, Inc., Peter Zijlstra
 */

#include <linux/kernel.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>	/* read_mapping_page */
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/sched/coredump.h>
#include <linux/export.h>
#include <linux/rmap.h>		/* anon_vma_prepare */
#include <linux/mmu_notifier.h>	/* set_pte_at_notify */
#include <linux/swap.h>		/* try_to_free_swap */
#include <linux/ptrace.h>	/* user_enable_single_step */
#include <linux/kdebug.h>	/* notifier mechanism */
#include "../../mm/internal.h"	/* munlock_vma_page */
#include <linux/percpu-rwsem.h>
#include <linux/task_work.h>
#include <linux/shmem_fs.h>

#include <linux/uprobes.h>


#define UINSNS_PER_PAGE			(PAGE_SIZE/UPROBE_XOL_SLOT_BYTES)

#define MAX_UPROBE_XOL_SLOTS		UINSNS_PER_PAGE


static struct rb_root uprobes_tree = RB_ROOT;
/*
 * allows us to skip the uprobe_mmap if there are no uprobe events active
 * at this time.  Probably a fine grained per inode count is better?
 */

#define no_uprobe_events()	RB_EMPTY_ROOT(&uprobes_tree)

static DEFINE_SPINLOCK(uprobes_treelock);	/* serialize rbtree access */


#define UPROBES_HASH_SZ	13
/* serialize uprobe->pending_list */

static struct mutex uprobes_mmap_mutex[UPROBES_HASH_SZ];

#define uprobes_mmap_hash(v)	(&uprobes_mmap_mutex[((unsigned long)(v)) % UPROBES_HASH_SZ])


static struct percpu_rw_semaphore dup_mmap_sem;

/* Have a copy of original instruction */

#define UPROBE_COPY_INSN	0


struct uprobe {
	
struct rb_node		rb_node;	/* node in the rb tree */
	
atomic_t		ref;
	
struct rw_semaphore	register_rwsem;
	
struct rw_semaphore	consumer_rwsem;
	
struct list_head	pending_list;
	
struct uprobe_consumer	*consumers;
	
struct inode		*inode;		/* Also hold a ref to inode */
	
loff_t			offset;
	
unsigned long		flags;

	/*
         * The generic code assumes that it has two members of unknown type
         * owned by the arch-specific code:
         *
         *      insn -  copy_insn() saves the original instruction here for
         *              arch_uprobe_analyze_insn().
         *
         *      ixol -  potentially modified instruction to execute out of
         *              line, copied to xol_area by xol_get_insn_slot().
         */
	
struct arch_uprobe	arch;
};

/*
 * Execute out of line area: anonymous executable mapping installed
 * by the probed task to execute the copy of the original instruction
 * mangled by set_swbp().
 *
 * On a breakpoint hit, thread contests for a slot.  It frees the
 * slot after singlestep. Currently a fixed number of slots are
 * allocated.
 */

struct xol_area {
	
wait_queue_head_t 		wq;		/* if all slots are busy */
	
atomic_t 			slot_count;	/* number of in-use slots */
	
unsigned long 			*bitmap;	/* 0 = free slot */

	
struct vm_special_mapping	xol_mapping;
	
struct page 			*pages[2];
	/*
         * We keep the vma's vm_start rather than a pointer to the vma
         * itself.  The probed process or a naughty kernel module could make
         * the vma go away, and we must handle that reasonably gracefully.
         */
	
unsigned long 			vaddr;		/* Page(s) of instruction slots */
};

/*
 * valid_vma: Verify if the specified vma is an executable vma
 * Relax restrictions while unregistering: vm_flags might have
 * changed after breakpoint was inserted.
 *      - is_register: indicates if we are in register context.
 *      - Return 1 if the specified virtual address is in an
 *        executable vma.
 */

static bool valid_vma(struct vm_area_struct *vma, bool is_register) { vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE; if (is_register) flags |= VM_WRITE; return vma->vm_file && (vma->vm_flags & flags) == VM_MAYEXEC; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju2758.70%125.00%
Oleg Nesterov1941.30%375.00%
Total46100.00%4100.00%


static unsigned long offset_to_vaddr(struct vm_area_struct *vma, loff_t offset) { return vma->vm_start + offset - ((loff_t)vma->vm_pgoff << PAGE_SHIFT); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju2369.70%133.33%
Oleg Nesterov1030.30%266.67%
Total33100.00%3100.00%


static loff_t vaddr_to_offset(struct vm_area_struct *vma, unsigned long vaddr) { return ((loff_t)vma->vm_pgoff << PAGE_SHIFT) + (vaddr - vma->vm_start); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov35100.00%1100.00%
Total35100.00%1100.00%

/** * __replace_page - replace page in vma by new page. * based on replace_page in mm/ksm.c * * @vma: vma that holds the pte pointing to page * @addr: address the old @page is mapped at * @page: the cowed page we are replacing by kpage * @kpage: the modified page we replace page by * * Returns 0 on success, -EFAULT on failure. */
static int __replace_page(struct vm_area_struct *vma, unsigned long addr, struct page *old_page, struct page *new_page) { struct mm_struct *mm = vma->vm_mm; struct page_vma_mapped_walk pvmw = { .page = old_page, .vma = vma, .address = addr, }; int err; /* For mmu_notifiers */ const unsigned long mmun_start = addr; const unsigned long mmun_end = addr + PAGE_SIZE; struct mem_cgroup *memcg; VM_BUG_ON_PAGE(PageTransHuge(old_page), old_page); err = mem_cgroup_try_charge(new_page, vma->vm_mm, GFP_KERNEL, &memcg, false); if (err) return err; /* For try_to_free_swap() and munlock_vma_page() below */ lock_page(old_page); mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); err = -EAGAIN; if (!page_vma_mapped_walk(&pvmw)) { mem_cgroup_cancel_charge(new_page, memcg, false); goto unlock; } VM_BUG_ON_PAGE(addr != pvmw.address, old_page); get_page(new_page); page_add_new_anon_rmap(new_page, vma, addr, false); mem_cgroup_commit_charge(new_page, memcg, false, false); lru_cache_add_active_or_unevictable(new_page, vma); if (!PageAnon(old_page)) { dec_mm_counter(mm, mm_counter_file(old_page)); inc_mm_counter(mm, MM_ANONPAGES); } flush_cache_page(vma, addr, pte_pfn(*pvmw.pte)); ptep_clear_flush_notify(vma, addr, pvmw.pte); set_pte_at_notify(mm, addr, pvmw.pte, mk_pte(new_page, vma->vm_page_prot)); page_remove_rmap(old_page, false); if (!page_mapped(old_page)) try_to_free_swap(old_page); page_vma_mapped_walk_done(&pvmw); if (vma->vm_flags & VM_LOCKED) munlock_vma_page(old_page); put_page(old_page); err = 0; unlock: mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); unlock_page(old_page); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju12135.28%213.33%
Oleg Nesterov7622.16%640.00%
Kirill A. Shutemov6619.24%320.00%
Johannes Weiner4111.95%16.67%
Haggai Eran3510.20%16.67%
Jerome Marchand30.87%16.67%
Joerg Roedel10.29%16.67%
Total343100.00%15100.00%

/** * is_swbp_insn - check if instruction is breakpoint instruction. * @insn: instruction to be checked. * Default implementation of is_swbp_insn * Returns true if @insn is a breakpoint instruction. */
bool __weak is_swbp_insn(uprobe_opcode_t *insn) { return *insn == UPROBE_SWBP_INSN; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju16100.00%2100.00%
Total16100.00%2100.00%

/** * is_trap_insn - check if instruction is breakpoint instruction. * @insn: instruction to be checked. * Default implementation of is_trap_insn * Returns true if @insn is a breakpoint instruction. * * This function is needed for the case where an architecture has multiple * trap instructions (like powerpc). */
bool __weak is_trap_insn(uprobe_opcode_t *insn) { return is_swbp_insn(insn); }

Contributors

PersonTokensPropCommitsCommitProp
Ananth N. Mavinakayanahalli16100.00%1100.00%
Total16100.00%1100.00%


static void copy_from_page(struct page *page, unsigned long vaddr, void *dst, int len) { void *kaddr = kmap_atomic(page); memcpy(dst, kaddr + (vaddr & ~PAGE_MASK), len); kunmap_atomic(kaddr); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov52100.00%2100.00%
Total52100.00%2100.00%


static void copy_to_page(struct page *page, unsigned long vaddr, const void *src, int len) { void *kaddr = kmap_atomic(page); memcpy(kaddr + (vaddr & ~PAGE_MASK), src, len); kunmap_atomic(kaddr); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov53100.00%1100.00%
Total53100.00%1100.00%


static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode) { uprobe_opcode_t old_opcode; bool is_swbp; /* * Note: We only check if the old_opcode is UPROBE_SWBP_INSN here. * We do not check if it is any other 'trap variant' which could * be conditional trap instruction such as the one powerpc supports. * * The logic is that we do not care if the underlying instruction * is a trap variant; uprobes always wins over any other (gdb) * breakpoint. */ copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE); is_swbp = is_swbp_insn(&old_opcode); if (is_swbp_insn(new_opcode)) { if (is_swbp) /* register: already installed? */ return 0; } else { if (!is_swbp) /* unregister: was it changed by us? */ return 0; } return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov7798.72%375.00%
Ananth N. Mavinakayanahalli11.28%125.00%
Total78100.00%4100.00%

/* * NOTE: * Expect the breakpoint instruction to be the smallest size instruction for * the architecture. If an arch has variable length instruction and the * breakpoint instruction is not of the smallest length instruction * supported by that architecture then we need to modify is_trap_at_addr and * uprobe_write_opcode accordingly. This would never be a problem for archs * that have fixed length instructions. * * uprobe_write_opcode - write the opcode at a given virtual address. * @mm: the probed process address space. * @vaddr: the virtual address to store the opcode. * @opcode: opcode to be written at @vaddr. * * Called with mm->mmap_sem held for write. * Return 0 (success) or a negative errno. */
int uprobe_write_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t opcode) { struct page *old_page, *new_page; struct vm_area_struct *vma; int ret; retry: /* Read the page with vaddr into memory */ ret = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE | FOLL_SPLIT, &old_page, &vma, NULL); if (ret <= 0) return ret; ret = verify_opcode(old_page, vaddr, &opcode); if (ret <= 0) goto put_old; ret = anon_vma_prepare(vma); if (ret) goto put_old; ret = -ENOMEM; new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr); if (!new_page) goto put_old; __SetPageUptodate(new_page); copy_highpage(new_page, old_page); copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); ret = __replace_page(vma, vaddr, old_page, new_page); put_page(new_page); put_old: put_page(old_page); if (unlikely(ret == -EAGAIN)) goto retry; return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju12363.40%321.43%
Oleg Nesterov6432.99%642.86%
Lorenzo Stoakes31.55%214.29%
Kirill A. Shutemov31.55%214.29%
Dave Hansen10.52%17.14%
Total194100.00%14100.00%

/** * set_swbp - store breakpoint at a given address. * @auprobe: arch specific probepoint information. * @mm: the probed process address space. * @vaddr: the virtual address to insert the opcode. * * For mm @mm, store the breakpoint instruction at @vaddr. * Return 0 (success) or a negative errno. */
int __weak set_swbp(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) { return uprobe_write_opcode(mm, vaddr, UPROBE_SWBP_INSN); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju2996.67%375.00%
Oleg Nesterov13.33%125.00%
Total30100.00%4100.00%

/** * set_orig_insn - Restore the original instruction. * @mm: the probed process address space. * @auprobe: arch specific probepoint information. * @vaddr: the virtual address to insert the opcode. * * For mm @mm, restore the original opcode (opcode) at @vaddr. * Return 0 (success) or a negative errno. */
int __weak set_orig_insn(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr) { return uprobe_write_opcode(mm, vaddr, *(uprobe_opcode_t *)&auprobe->insn); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju3694.74%360.00%
Oleg Nesterov25.26%240.00%
Total38100.00%5100.00%


static struct uprobe *get_uprobe(struct uprobe *uprobe) { atomic_inc(&uprobe->ref); return uprobe; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov24100.00%1100.00%
Total24100.00%1100.00%


static void put_uprobe(struct uprobe *uprobe) { if (atomic_dec_and_test(&uprobe->ref)) kfree(uprobe); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov26100.00%1100.00%
Total26100.00%1100.00%


static int match_uprobe(struct uprobe *l, struct uprobe *r) { if (l->inode < r->inode) return -1; if (l->inode > r->inode) return 1; if (l->offset < r->offset) return -1; if (l->offset > r->offset) return 1; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju73100.00%1100.00%
Total73100.00%1100.00%


static struct uprobe *__find_uprobe(struct inode *inode, loff_t offset) { struct uprobe u = { .inode = inode, .offset = offset }; struct rb_node *n = uprobes_tree.rb_node; struct uprobe *uprobe; int match; while (n) { uprobe = rb_entry(n, struct uprobe, rb_node); match = match_uprobe(&u, uprobe); if (!match) return get_uprobe(uprobe); if (match < 0) n = n->rb_left; else n = n->rb_right; } return NULL; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju10898.18%150.00%
Oleg Nesterov21.82%150.00%
Total110100.00%2100.00%

/* * Find a uprobe corresponding to a given inode:offset * Acquires uprobes_treelock */
static struct uprobe *find_uprobe(struct inode *inode, loff_t offset) { struct uprobe *uprobe; spin_lock(&uprobes_treelock); uprobe = __find_uprobe(inode, offset); spin_unlock(&uprobes_treelock); return uprobe; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju4395.56%150.00%
Oleg Nesterov24.44%150.00%
Total45100.00%2100.00%


static struct uprobe *__insert_uprobe(struct uprobe *uprobe) { struct rb_node **p = &uprobes_tree.rb_node; struct rb_node *parent = NULL; struct uprobe *u; int match; while (*p) { parent = *p; u = rb_entry(parent, struct uprobe, rb_node); match = match_uprobe(uprobe, u); if (!match) return get_uprobe(u); if (match < 0) p = &parent->rb_left; else p = &parent->rb_right; } u = NULL; rb_link_node(&uprobe->rb_node, parent, p); rb_insert_color(&uprobe->rb_node, &uprobes_tree); /* get access + creation ref */ atomic_set(&uprobe->ref, 2); return u; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju14398.62%150.00%
Oleg Nesterov21.38%150.00%
Total145100.00%2100.00%

/* * Acquire uprobes_treelock. * Matching uprobe already exists in rbtree; * increment (access refcount) and return the matching uprobe. * * No matching uprobe; insert the uprobe in rb_tree; * get a double refcount (access + creation) and return NULL. */
static struct uprobe *insert_uprobe(struct uprobe *uprobe) { struct uprobe *u; spin_lock(&uprobes_treelock); u = __insert_uprobe(uprobe); spin_unlock(&uprobes_treelock); return u; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju3895.00%150.00%
Oleg Nesterov25.00%150.00%
Total40100.00%2100.00%


static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) { struct uprobe *uprobe, *cur_uprobe; uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL); if (!uprobe) return NULL; uprobe->inode = igrab(inode); uprobe->offset = offset; init_rwsem(&uprobe->register_rwsem); init_rwsem(&uprobe->consumer_rwsem); /* add to uprobes_tree, sorted on inode:offset */ cur_uprobe = insert_uprobe(uprobe); /* a uprobe exists for this inode:offset combination */ if (cur_uprobe) { kfree(uprobe); uprobe = cur_uprobe; iput(inode); } return uprobe; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju10092.59%150.00%
Oleg Nesterov87.41%150.00%
Total108100.00%2100.00%


static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc) { down_write(&uprobe->consumer_rwsem); uc->next = uprobe->consumers; uprobe->consumers = uc; up_write(&uprobe->consumer_rwsem); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju4393.48%250.00%
Oleg Nesterov24.35%125.00%
Ingo Molnar12.17%125.00%
Total46100.00%4100.00%

/* * For uprobe @uprobe, delete the consumer @uc. * Return true if the @uc is deleted successfully * or return false. */
static bool consumer_del(struct uprobe *uprobe, struct uprobe_consumer *uc) { struct uprobe_consumer **con; bool ret = false; down_write(&uprobe->consumer_rwsem); for (con = &uprobe->consumers; *con; con = &(*con)->next) { if (*con == uc) { *con = uc->next; ret = true; break; } } up_write(&uprobe->consumer_rwsem); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju9098.90%266.67%
Ingo Molnar11.10%133.33%
Total91100.00%3100.00%


static int __copy_insn(struct address_space *mapping, struct file *filp, void *insn, int nbytes, loff_t offset) { struct page *page; /* * Ensure that the page that has the original instruction is populated * and in page-cache. If ->readpage == NULL it must be shmem_mapping(), * see uprobe_register(). */ if (mapping->a_ops->readpage) page = read_mapping_page(mapping, offset >> PAGE_SHIFT, filp); else page = shmem_read_mapping_page(mapping, offset >> PAGE_SHIFT); if (IS_ERR(page)) return PTR_ERR(page); copy_from_page(page, offset, insn, nbytes); put_page(page); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju6567.01%112.50%
Oleg Nesterov2929.90%675.00%
Kirill A. Shutemov33.09%112.50%
Total97100.00%8100.00%


static int copy_insn(struct uprobe *uprobe, struct file *filp) { struct address_space *mapping = uprobe->inode->i_mapping; loff_t offs = uprobe->offset; void *insn = &uprobe->arch.insn; int size = sizeof(uprobe->arch.insn); int len, err = -EIO; /* Copy only available bytes, -EIO if nothing was read */ do { if (offs >= i_size_read(uprobe->inode)) break; len = min_t(int, size, PAGE_SIZE - (offs & ~PAGE_MASK)); err = __copy_insn(mapping, filp, insn, len, offs); if (err) break; insn += len; offs += len; size -= len; } while (size); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov9266.19%480.00%
Srikar Dronamraju4733.81%120.00%
Total139100.00%5100.00%


static int prepare_uprobe(struct uprobe *uprobe, struct file *file, struct mm_struct *mm, unsigned long vaddr) { int ret = 0; if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) return ret; /* TODO: move this into _register, until then we abuse this sem. */ down_write(&uprobe->consumer_rwsem); if (test_bit(UPROBE_COPY_INSN, &uprobe->flags)) goto out; ret = copy_insn(uprobe, file); if (ret) goto out; ret = -ENOTSUPP; if (is_trap_insn((uprobe_opcode_t *)&uprobe->arch.insn)) goto out; ret = arch_uprobe_analyze_insn(&uprobe->arch, mm, vaddr); if (ret) goto out; /* uprobe_write_opcode() assumes we don't cross page boundary */ BUG_ON((uprobe->offset & ~PAGE_MASK) + UPROBE_SWBP_INSN_SIZE > PAGE_SIZE); smp_wmb(); /* pairs with rmb() in find_active_uprobe() */ set_bit(UPROBE_COPY_INSN, &uprobe->flags); out: up_write(&uprobe->consumer_rwsem); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov9051.72%1062.50%
Srikar Dronamraju8247.13%425.00%
Ananth N. Mavinakayanahalli21.15%212.50%
Total174100.00%16100.00%


static inline bool consumer_filter(struct uprobe_consumer *uc, enum uprobe_filter_ctx ctx, struct mm_struct *mm) { return !uc->filter || uc->filter(uc, ctx, mm); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov38100.00%2100.00%
Total38100.00%2100.00%


static bool filter_chain(struct uprobe *uprobe, enum uprobe_filter_ctx ctx, struct mm_struct *mm) { struct uprobe_consumer *uc; bool ret = false; down_read(&uprobe->consumer_rwsem); for (uc = uprobe->consumers; uc; uc = uc->next) { ret = consumer_filter(uc, ctx, mm); if (ret) break; } up_read(&uprobe->consumer_rwsem); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov83100.00%4100.00%
Total83100.00%4100.00%


static int install_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, struct vm_area_struct *vma, unsigned long vaddr) { bool first_uprobe; int ret; ret = prepare_uprobe(uprobe, vma->vm_file, mm, vaddr); if (ret) return ret; /* * set MMF_HAS_UPROBES in advance for uprobe_pre_sstep_notifier(), * the task can hit this breakpoint right after __replace_page(). */ first_uprobe = !test_bit(MMF_HAS_UPROBES, &mm->flags); if (first_uprobe) set_bit(MMF_HAS_UPROBES, &mm->flags); ret = set_swbp(&uprobe->arch, mm, vaddr); if (!ret) clear_bit(MMF_RECALC_UPROBES, &mm->flags); else if (first_uprobe) clear_bit(MMF_HAS_UPROBES, &mm->flags); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov11186.72%450.00%
Srikar Dronamraju1713.28%450.00%
Total128100.00%8100.00%


static int remove_breakpoint(struct uprobe *uprobe, struct mm_struct *mm, unsigned long vaddr) { set_bit(MMF_RECALC_UPROBES, &mm->flags); return set_orig_insn(&uprobe->arch, mm, vaddr); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju2865.12%350.00%
Oleg Nesterov1534.88%350.00%
Total43100.00%6100.00%


static inline bool uprobe_is_active(struct uprobe *uprobe) { return !RB_EMPTY_NODE(&uprobe->rb_node); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov22100.00%1100.00%
Total22100.00%1100.00%

/* * There could be threads that have already hit the breakpoint. They * will recheck the current insn and restart if find_uprobe() fails. * See find_active_uprobe(). */
static void delete_uprobe(struct uprobe *uprobe) { if (WARN_ON(!uprobe_is_active(uprobe))) return; spin_lock(&uprobes_treelock); rb_erase(&uprobe->rb_node, &uprobes_tree); spin_unlock(&uprobes_treelock); RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ iput(uprobe->inode); put_uprobe(uprobe); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju4465.67%133.33%
Oleg Nesterov2334.33%266.67%
Total67100.00%3100.00%

struct map_info { struct map_info *next; struct mm_struct *mm; unsigned long vaddr; };
static inline struct map_info *free_map_info(struct map_info *info) { struct map_info *next = info->next; kfree(info); return next; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov2374.19%150.00%
Srikar Dronamraju825.81%150.00%
Total31100.00%2100.00%


static struct map_info * build_map_info(struct address_space *mapping, loff_t offset, bool is_register) { unsigned long pgoff = offset >> PAGE_SHIFT; struct vm_area_struct *vma; struct map_info *curr = NULL; struct map_info *prev = NULL; struct map_info *info; int more = 0; again: i_mmap_lock_read(mapping); vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { if (!valid_vma(vma, is_register)) continue; if (!prev && !more) { /* * Needs GFP_NOWAIT to avoid i_mmap_rwsem recursion through * reclaim. This is optimistic, no harm done if it fails. */ prev = kmalloc(sizeof(struct map_info), GFP_NOWAIT | __GFP_NOMEMALLOC | __GFP_NOWARN); if (prev) prev->next = NULL; } if (!prev) { more++; continue; } if (!mmget_not_zero(vma->vm_mm)) continue; info = prev; prev = prev->next; info->next = curr; curr = info; info->mm = vma->vm_mm; info->vaddr = offset_to_vaddr(vma, offset); } i_mmap_unlock_read(mapping); if (!more) goto out; prev = curr; while (curr) { mmput(curr->mm); curr = curr->next; } do { info = kmalloc(sizeof(struct map_info), GFP_KERNEL); if (!info) { curr = ERR_PTR(-ENOMEM); goto out; } info->next = prev; prev = info; } while (--more); goto again; out: while (prev) prev = free_map_info(prev); return curr; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov18062.07%330.00%
Srikar Dronamraju10335.52%220.00%
Davidlohr Bueso A31.03%220.00%
Ingo Molnar20.69%110.00%
Vegard Nossum10.34%110.00%
Michel Lespinasse10.34%110.00%
Total290100.00%10100.00%


static int register_for_each_vma(struct uprobe *uprobe, struct uprobe_consumer *new) { bool is_register = !!new; struct map_info *info; int err = 0; percpu_down_write(&dup_mmap_sem); info = build_map_info(uprobe->inode->i_mapping, uprobe->offset, is_register); if (IS_ERR(info)) { err = PTR_ERR(info); goto out; } while (info) { struct mm_struct *mm = info->mm; struct vm_area_struct *vma; if (err && is_register) goto free; down_write(&mm->mmap_sem); vma = find_vma(mm, info->vaddr); if (!vma || !valid_vma(vma, is_register) || file_inode(vma->vm_file) != uprobe->inode) goto unlock; if (vma->vm_start > info->vaddr || vaddr_to_offset(vma, info->vaddr) != uprobe->offset) goto unlock; if (is_register) { /* consult only the "caller", new consumer. */ if (consumer_filter(new, UPROBE_FILTER_REGISTER, mm)) err = install_breakpoint(uprobe, mm, vma, info->vaddr); } else if (test_bit(MMF_HAS_UPROBES, &mm->flags)) { if (!filter_chain(uprobe, UPROBE_FILTER_UNREGISTER, mm)) err |= remove_breakpoint(uprobe, mm, info->vaddr); } unlock: up_write(&mm->mmap_sem); free: mmput(mm); info = free_map_info(info); } out: percpu_up_write(&dup_mmap_sem); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov15554.58%1076.92%
Srikar Dronamraju12644.37%215.38%
Ingo Molnar31.06%17.69%
Total284100.00%13100.00%


static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc) { consumer_add(uprobe, uc); return register_for_each_vma(uprobe, uc); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju1651.61%120.00%
Oleg Nesterov1445.16%360.00%
Ingo Molnar13.23%120.00%
Total31100.00%5100.00%


static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc) { int err; if (WARN_ON(!consumer_del(uprobe, uc))) return; err = register_for_each_vma(uprobe, NULL); /* TODO : cant unregister? schedule a worker thread */ if (!uprobe->consumers && !err) delete_uprobe(uprobe); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov4068.97%466.67%
Srikar Dronamraju1729.31%116.67%
Ingo Molnar11.72%116.67%
Total58100.00%6100.00%

/* * uprobe_register - register a probe * @inode: the file in which the probe has to be placed. * @offset: offset from the start of the file. * @uc: information on howto handle the probe.. * * Apart from the access refcount, uprobe_register() takes a creation * refcount (thro alloc_uprobe) if and only if this @uprobe is getting * inserted into the rbtree (i.e first consumer for a @inode:@offset * tuple). Creation refcount stops uprobe_unregister from freeing the * @uprobe even before the register operation is complete. Creation * refcount is released when the last @uc for the @uprobe * unregisters. * * Return errno if it cannot successully install probes * else return 0 (success) */
int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { struct uprobe *uprobe; int ret; /* Uprobe must have at least one set consumer */ if (!uc->handler && !uc->ret_handler) return -EINVAL; /* copy_insn() uses read_mapping_page() or shmem_read_mapping_page() */ if (!inode->i_mapping->a_ops->readpage && !shmem_mapping(inode->i_mapping)) return -EIO; /* Racy, just to catch the obvious mistakes */ if (offset > i_size_read(inode)) return -EINVAL; retry: uprobe = alloc_uprobe(inode, offset); if (!uprobe) return -ENOMEM; /* * We can race with uprobe_unregister()->delete_uprobe(). * Check uprobe_is_active() and retry if it is false. */ down_write(&uprobe->register_rwsem); ret = -EAGAIN; if (likely(uprobe_is_active(uprobe))) { ret = __uprobe_register(uprobe, uc); if (ret) __uprobe_unregister(uprobe, uc); } up_write(&uprobe->register_rwsem); put_uprobe(uprobe); if (unlikely(ret == -EAGAIN)) goto retry; return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov8347.16%861.54%
Srikar Dronamraju7039.77%215.38%
Anton Arapov179.66%17.69%
Ingo Molnar42.27%17.69%
Sebastian Andrzej Siewior21.14%17.69%
Total176100.00%13100.00%

EXPORT_SYMBOL_GPL(uprobe_register); /* * uprobe_apply - unregister a already registered probe. * @inode: the file in which the probe has to be removed. * @offset: offset from the start of the file. * @uc: consumer which wants to add more or remove some breakpoints * @add: add or remove the breakpoints */
int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool add) { struct uprobe *uprobe; struct uprobe_consumer *con; int ret = -ENOENT; uprobe = find_uprobe(inode, offset); if (WARN_ON(!uprobe)) return ret; down_write(&uprobe->register_rwsem); for (con = uprobe->consumers; con && con != uc ; con = con->next) ; if (con) ret = register_for_each_vma(uprobe, add ? uc : NULL); up_write(&uprobe->register_rwsem); put_uprobe(uprobe); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov119100.00%2100.00%
Total119100.00%2100.00%

/* * uprobe_unregister - unregister a already registered probe. * @inode: the file in which the probe has to be removed. * @offset: offset from the start of the file. * @uc: identify which probe if multiple probes are colocated. */
void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { struct uprobe *uprobe; uprobe = find_uprobe(inode, offset); if (WARN_ON(!uprobe)) return; down_write(&uprobe->register_rwsem); __uprobe_unregister(uprobe, uc); up_write(&uprobe->register_rwsem); put_uprobe(uprobe); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju4565.22%228.57%
Oleg Nesterov2231.88%457.14%
Ingo Molnar22.90%114.29%
Total69100.00%7100.00%

EXPORT_SYMBOL_GPL(uprobe_unregister);
static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm) { struct vm_area_struct *vma; int err = 0; down_read(&mm->mmap_sem); for (vma = mm->mmap; vma; vma = vma->vm_next) { unsigned long vaddr; loff_t offset; if (!valid_vma(vma, false) || file_inode(vma->vm_file) != uprobe->inode) continue; offset = (loff_t)vma->vm_pgoff << PAGE_SHIFT; if (uprobe->offset < offset || uprobe->offset >= offset + vma->vm_end - vma->vm_start) continue; vaddr = offset_to_vaddr(vma, uprobe->offset); err |= remove_breakpoint(uprobe, mm, vaddr); } up_read(&mm->mmap_sem); return err; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov148100.00%2100.00%
Total148100.00%2100.00%


static struct rb_node * find_node_in_range(struct inode *inode, loff_t min, loff_t max) { struct rb_node *n = uprobes_tree.rb_node; while (n) { struct uprobe *u = rb_entry(n, struct uprobe, rb_node); if (inode < u->inode) { n = n->rb_left; } else if (inode > u->inode) { n = n->rb_right; } else { if (max < u->offset) n = n->rb_left; else if (min > u->offset) n = n->rb_right; else break; } } return n; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju6655.46%150.00%
Oleg Nesterov5344.54%150.00%
Total119100.00%2100.00%

/* * For a given range in vma, build a list of probes that need to be inserted. */
static void build_probe_list(struct inode *inode, struct vm_area_struct *vma, unsigned long start, unsigned long end, struct list_head *head) { loff_t min, max; struct rb_node *n, *t; struct uprobe *u; INIT_LIST_HEAD(head); min = vaddr_to_offset(vma, start); max = min + (end - start) - 1; spin_lock(&uprobes_treelock); n = find_node_in_range(inode, min, max); if (n) { for (t = n; t; t = rb_prev(t)) { u = rb_entry(t, struct uprobe, rb_node); if (u->inode != inode || u->offset < min) break; list_add(&u->pending_list, head); get_uprobe(u); } for (t = n; (t = rb_next(t)); ) { u = rb_entry(t, struct uprobe, rb_node); if (u->inode != inode || u->offset > max) break; list_add(&u->pending_list, head); get_uprobe(u); } } spin_unlock(&uprobes_treelock); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov14163.80%480.00%
Srikar Dronamraju8036.20%120.00%
Total221100.00%5100.00%

/* * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. * * Currently we ignore all errors and always return 0, the callers * can't handle the failure anyway. */
int uprobe_mmap(struct vm_area_struct *vma) { struct list_head tmp_list; struct uprobe *uprobe, *u; struct inode *inode; if (no_uprobe_events() || !valid_vma(vma, true)) return 0; inode = file_inode(vma->vm_file); if (!inode) return 0; mutex_lock(uprobes_mmap_hash(inode)); build_probe_list(inode, vma, vma->vm_start, vma->vm_end, &tmp_list); /* * We can race with uprobe_unregister(), this uprobe can be already * removed. But in this case filter_chain() must return false, all * consumers have gone away. */ list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) { if (!fatal_signal_pending(current) && filter_chain(uprobe, UPROBE_FILTER_MMAP, vma->vm_mm)) { unsigned long vaddr = offset_to_vaddr(vma, uprobe->offset); install_breakpoint(uprobe, vma->vm_mm, vma, vaddr); } put_uprobe(uprobe); } mutex_unlock(uprobes_mmap_hash(inode)); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju11570.99%216.67%
Oleg Nesterov4326.54%975.00%
Ingo Molnar42.47%18.33%
Total162100.00%12100.00%


static bool vma_has_uprobes(struct vm_area_struct *vma, unsigned long start, unsigned long end) { loff_t min, max; struct inode *inode; struct rb_node *n; inode = file_inode(vma->vm_file); min = vaddr_to_offset(vma, start); max = min + (end - start) - 1; spin_lock(&uprobes_treelock); n = find_node_in_range(inode, min, max); spin_unlock(&uprobes_treelock); return !!n; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov92100.00%2100.00%
Total92100.00%2100.00%

/* * Called in context of a munmap of a vma. */
void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned long end) { if (no_uprobe_events() || !valid_vma(vma, false)) return; if (!atomic_read(&vma->vm_mm->mm_users)) /* called by mmput() ? */ return; if (!test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags) || test_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags)) return; if (vma_has_uprobes(vma, start, end)) set_bit(MMF_RECALC_UPROBES, &vma->vm_mm->flags); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov5859.18%466.67%
Srikar Dronamraju4040.82%233.33%
Total98100.00%6100.00%

/* Slot allocation for XOL */
static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) { struct vm_area_struct *vma; int ret; if (down_write_killable(&mm->mmap_sem)) return -EINTR; if (mm->uprobes_state.xol_area) { ret = -EALREADY; goto fail; } if (!area->vaddr) { /* Try to map as high as possible, this is only a hint. */ area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0); if (area->vaddr & ~PAGE_MASK) { ret = area->vaddr; goto fail; } } vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE, VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->xol_mapping); if (IS_ERR(vma)) { ret = PTR_ERR(vma); goto fail; } ret = 0; smp_wmb(); /* pairs with get_xol_area() */ mm->uprobes_state.xol_area = area; fail: up_write(&mm->mmap_sem); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju12368.72%337.50%
Oleg Nesterov4826.82%450.00%
Michal Hocko84.47%112.50%
Total179100.00%8100.00%


static struct xol_area *__create_xol_area(unsigned long vaddr) { struct mm_struct *mm = current->mm; uprobe_opcode_t insn = UPROBE_SWBP_INSN; struct xol_area *area; area = kmalloc(sizeof(*area), GFP_KERNEL); if (unlikely(!area)) goto out; area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long), GFP_KERNEL); if (!area->bitmap) goto free_area; area->xol_mapping.name = "[uprobes]"; area->xol_mapping.fault = NULL; area->xol_mapping.pages = area->pages; area->pages[0] = alloc_page(GFP_HIGHUSER); if (!area->pages[0]) goto free_bitmap; area->pages[1] = NULL; area->vaddr = vaddr; init_waitqueue_head(&area->wq); /* Reserve the 1st slot for get_trampoline_vaddr() */ set_bit(0, area->bitmap); atomic_set(&area->slot_count, 1); arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE); if (!xol_add_vma(mm, area)) return area; __free_page(area->pages[0]); free_bitmap: kfree(area->bitmap); free_area: kfree(area); out: return NULL; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov12552.30%758.33%
Srikar Dronamraju8836.82%325.00%
Anton Arapov2510.46%18.33%
Marcin Nowakowski10.42%18.33%
Total239100.00%12100.00%

/* * get_xol_area - Allocate process's xol_area if necessary. * This area will be used for storing instructions for execution out of line. * * Returns the allocated area or NULL. */
static struct xol_area *get_xol_area(void) { struct mm_struct *mm = current->mm; struct xol_area *area; if (!mm->uprobes_state.xol_area) __create_xol_area(0); area = mm->uprobes_state.xol_area; smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ return area; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov5094.34%375.00%
Srikar Dronamraju35.66%125.00%
Total53100.00%4100.00%

/* * uprobe_clear_state - Free the area allocated for slots. */
void uprobe_clear_state(struct mm_struct *mm) { struct xol_area *area = mm->uprobes_state.xol_area; if (!area) return; put_page(area->pages[0]); kfree(area->bitmap); kfree(area); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju4591.84%150.00%
Oleg Nesterov48.16%150.00%
Total49100.00%2100.00%


void uprobe_start_dup_mmap(void) { percpu_down_read(&dup_mmap_sem); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov13100.00%1100.00%
Total13100.00%1100.00%


void uprobe_end_dup_mmap(void) { percpu_up_read(&dup_mmap_sem); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov13100.00%1100.00%
Total13100.00%1100.00%


void uprobe_dup_mmap(struct mm_struct *oldmm, struct mm_struct *newmm) { if (test_bit(MMF_HAS_UPROBES, &oldmm->flags)) { set_bit(MMF_HAS_UPROBES, &newmm->flags); /* unconditionally, dup_mmap() skips VM_DONTCOPY vmas */ set_bit(MMF_RECALC_UPROBES, &newmm->flags); } }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov50100.00%2100.00%
Total50100.00%2100.00%

/* * - search for a free slot. */
static unsigned long xol_take_insn_slot(struct xol_area *area) { unsigned long slot_addr; int slot_nr; do { slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE); if (slot_nr < UINSNS_PER_PAGE) { if (!test_and_set_bit(slot_nr, area->bitmap)) break; slot_nr = UINSNS_PER_PAGE; continue; } wait_event(area->wq, (atomic_read(&area->slot_count) < UINSNS_PER_PAGE)); } while (slot_nr >= UINSNS_PER_PAGE); slot_addr = area->vaddr + (slot_nr * UPROBE_XOL_SLOT_BYTES); atomic_inc(&area->slot_count); return slot_addr; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju108100.00%1100.00%
Total108100.00%1100.00%

/* * xol_get_insn_slot - allocate a slot for xol. * Returns the allocated slot address or 0. */
static unsigned long xol_get_insn_slot(struct uprobe *uprobe) { struct xol_area *area; unsigned long xol_vaddr; area = get_xol_area(); if (!area) return 0; xol_vaddr = xol_take_insn_slot(area); if (unlikely(!xol_vaddr)) return 0; arch_uprobe_copy_ixol(area->pages[0], xol_vaddr, &uprobe->arch.ixol, sizeof(uprobe->arch.ixol)); return xol_vaddr; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju6477.11%114.29%
Oleg Nesterov1821.69%571.43%
Victor Kamensky11.20%114.29%
Total83100.00%7100.00%

/* * xol_free_insn_slot - If slot was earlier allocated by * @xol_get_insn_slot(), make the slot available for * subsequent requests. */
static void xol_free_insn_slot(struct task_struct *tsk) { struct xol_area *area; unsigned long vma_end; unsigned long slot_addr; if (!tsk->mm || !tsk->mm->uprobes_state.xol_area || !tsk->utask) return; slot_addr = tsk->utask->xol_vaddr; if (unlikely(!slot_addr)) return; area = tsk->mm->uprobes_state.xol_area; vma_end = area->vaddr + PAGE_SIZE; if (area->vaddr <= slot_addr && slot_addr < vma_end) { unsigned long offset; int slot_nr; offset = slot_addr - area->vaddr; slot_nr = offset / UPROBE_XOL_SLOT_BYTES; if (slot_nr >= UINSNS_PER_PAGE) return; clear_bit(slot_nr, area->bitmap); atomic_dec(&area->slot_count); smp_mb__after_atomic(); /* pairs with prepare_to_wait() */ if (waitqueue_active(&area->wq)) wake_up(&area->wq); tsk->utask->xol_vaddr = 0; } }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju16697.65%150.00%
Oleg Nesterov42.35%150.00%
Total170100.00%2100.00%


void __weak arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr, void *src, unsigned long len) { /* Initialize the slot */ copy_to_page(page, vaddr, src, len); /* * We probably need flush_icache_user_range() but it needs vma. * This should work on most of architectures by default. If * architecture needs to do something different it can define * its own version of the function. */ flush_dcache_page(page); }

Contributors

PersonTokensPropCommitsCommitProp
Victor Kamensky41100.00%1100.00%
Total41100.00%1100.00%

/** * uprobe_get_swbp_addr - compute address of swbp given post-swbp regs * @regs: Reflects the saved state of the task after it has hit a breakpoint * instruction. * Return the address of the breakpoint instruction. */
unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs) { return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju20100.00%1100.00%
Total20100.00%1100.00%


unsigned long uprobe_get_trap_addr(struct pt_regs *regs) { struct uprobe_task *utask = current->utask; if (unlikely(utask && utask->active_uprobe)) return utask->vaddr; return instruction_pointer(regs); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov42100.00%1100.00%
Total42100.00%1100.00%


static struct return_instance *free_ret_instance(struct return_instance *ri) { struct return_instance *next = ri->next; put_uprobe(ri->uprobe); kfree(ri); return next; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov37100.00%1100.00%
Total37100.00%1100.00%

/* * Called with no locks held. * Called in context of a exiting or a exec-ing thread. */
void uprobe_free_utask(struct task_struct *t) { struct uprobe_task *utask = t->utask; struct return_instance *ri; if (!utask) return; if (utask->active_uprobe) put_uprobe(utask->active_uprobe); ri = utask->return_instances; while (ri) ri = free_ret_instance(ri); xol_free_insn_slot(t); kfree(utask); t->utask = NULL; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju5471.05%133.33%
Anton Arapov2026.32%133.33%
Oleg Nesterov22.63%133.33%
Total76100.00%3100.00%

/* * Allocate a uprobe_task object for the task if if necessary. * Called when the thread hits a breakpoint. * * Returns: * - pointer to new uprobe_task on success * - NULL otherwise */
static struct uprobe_task *get_utask(void) { if (!current->utask) current->utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); return current->utask; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju2464.86%266.67%
Oleg Nesterov1335.14%133.33%
Total37100.00%3100.00%


static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask) { struct uprobe_task *n_utask; struct return_instance **p, *o, *n; n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL); if (!n_utask) return -ENOMEM; t->utask = n_utask; p = &n_utask->return_instances; for (o = o_utask->return_instances; o; o = o->next) { n = kmalloc(sizeof(struct return_instance), GFP_KERNEL); if (!n) return -ENOMEM; *n = *o; get_uprobe(n->uprobe); n->next = NULL; *p = n; p = &n->next; n_utask->depth++; } return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov147100.00%2100.00%
Total147100.00%2100.00%


static void uprobe_warn(struct task_struct *t, const char *msg) { pr_warn("uprobe: %s:%d failed to %s\n", current->comm, current->pid, msg); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov31100.00%1100.00%
Total31100.00%1100.00%


static void dup_xol_work(struct callback_head *work) { if (current->flags & PF_EXITING) return; if (!__create_xol_area(current->utask->dup_xol_addr) && !fatal_signal_pending(current)) uprobe_warn(current, "dup xol area"); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov3986.67%266.67%
Michal Hocko613.33%133.33%
Total45100.00%3100.00%

/* * Called in context of a new clone/fork from copy_process. */
void uprobe_copy_process(struct task_struct *t, unsigned long flags) { struct uprobe_task *utask = current->utask; struct mm_struct *mm = current->mm; struct xol_area *area; t->utask = NULL; if (!utask || !utask->return_instances) return; if (mm == t->mm && !(flags & CLONE_VFORK)) return; if (dup_utask(t, utask)) return uprobe_warn(t, "dup ret instances"); /* The task can fork() after dup_xol_work() fails */ area = mm->uprobes_state.xol_area; if (!area) return uprobe_warn(t, "dup xol area"); if (mm == t->mm) return; t->utask->dup_xol_addr = area->vaddr; init_task_work(&t->utask->dup_xol_work, dup_xol_work); task_work_add(t, &t->utask->dup_xol_work, true); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov154100.00%6100.00%
Total154100.00%6100.00%

/* * Current area->vaddr notion assume the trampoline address is always * equal area->vaddr. * * Returns -1 in case the xol_area is not allocated. */
static unsigned long get_trampoline_vaddr(void) { struct xol_area *area; unsigned long trampoline_vaddr = -1; area = current->mm->uprobes_state.xol_area; smp_read_barrier_depends(); if (area) trampoline_vaddr = area->vaddr; return trampoline_vaddr; }

Contributors

PersonTokensPropCommitsCommitProp
Anton Arapov47100.00%1100.00%
Total47100.00%1100.00%


static void cleanup_return_instances(struct uprobe_task *utask, bool chained, struct pt_regs *regs) { struct return_instance *ri = utask->return_instances; enum rp_check ctx = chained ? RP_CHECK_CHAIN_CALL : RP_CHECK_CALL; while (ri && !arch_uretprobe_is_alive(ri, ctx, regs)) { ri = free_ret_instance(ri); utask->depth--; } utask->return_instances = ri; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov72100.00%3100.00%
Total72100.00%3100.00%


static void prepare_uretprobe(struct uprobe *uprobe, struct pt_regs *regs) { struct return_instance *ri; struct uprobe_task *utask; unsigned long orig_ret_vaddr, trampoline_vaddr; bool chained; if (!get_xol_area()) return; utask = get_utask(); if (!utask) return; if (utask->depth >= MAX_URETPROBE_DEPTH) { printk_ratelimited(KERN_INFO "uprobe: omit uretprobe due to" " nestedness limit pid/tgid=%d/%d\n", current->pid, current->tgid); return; } ri = kmalloc(sizeof(struct return_instance), GFP_KERNEL); if (!ri) return; trampoline_vaddr = get_trampoline_vaddr(); orig_ret_vaddr = arch_uretprobe_hijack_return_addr(trampoline_vaddr, regs); if (orig_ret_vaddr == -1) goto fail; /* drop the entries invalidated by longjmp() */ chained = (orig_ret_vaddr == trampoline_vaddr); cleanup_return_instances(utask, chained, regs); /* * We don't want to keep trampoline address in stack, rather keep the * original return address of first caller thru all the consequent * instances. This also makes breakpoint unwrapping easier. */ if (chained) { if (!utask->return_instances) { /* * This situation is not possible. Likely we have an * attack from user-space. */ uprobe_warn(current, "handle tail call"); goto fail; } orig_ret_vaddr = utask->return_instances->orig_ret_vaddr; } ri->uprobe = get_uprobe(uprobe); ri->func = instruction_pointer(regs); ri->stack = user_stack_pointer(regs); ri->orig_ret_vaddr = orig_ret_vaddr; ri->chained = chained; utask->depth++; ri->next = utask->return_instances; utask->return_instances = ri; return; fail: kfree(ri); }

Contributors

PersonTokensPropCommitsCommitProp
Anton Arapov20685.48%228.57%
Oleg Nesterov3514.52%571.43%
Total241100.00%7100.00%

/* Prepare to single-step probed instruction out of line. */
static int pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) { struct uprobe_task *utask; unsigned long xol_vaddr; int err; utask = get_utask(); if (!utask) return -ENOMEM; xol_vaddr = xol_get_insn_slot(uprobe); if (!xol_vaddr) return -ENOMEM; utask->xol_vaddr = xol_vaddr; utask->vaddr = bp_vaddr; err = arch_uprobe_pre_xol(&uprobe->arch, regs); if (unlikely(err)) { xol_free_insn_slot(current); return err; } utask->active_uprobe = uprobe; utask->state = UTASK_SSTEP; return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov8471.19%360.00%
Srikar Dronamraju3428.81%240.00%
Total118100.00%5100.00%

/* * If we are singlestepping, then ensure this thread is not connected to * non-fatal signals until completion of singlestep. When xol insn itself * triggers the signal, restart the original insn even if the task is * already SIGKILL'ed (since coredump should report the correct ip). This * is even more important if the task has a handler for SIGSEGV/etc, The * _same_ instruction should be repeated again after return from the signal * handler, and SSTEP can never finish in this case. */
bool uprobe_deny_signal(void) { struct task_struct *t = current; struct uprobe_task *utask = t->utask; if (likely(!utask || !utask->active_uprobe)) return false; WARN_ON_ONCE(utask->state != UTASK_SSTEP); if (signal_pending(t)) { spin_lock_irq(&t->sighand->siglock); clear_tsk_thread_flag(t, TIF_SIGPENDING); spin_unlock_irq(&t->sighand->siglock); if (__fatal_signal_pending(t) || arch_uprobe_xol_was_trapped(t)) { utask->state = UTASK_SSTEP_TRAPPED; set_tsk_thread_flag(t, TIF_UPROBE); } } return true; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju114100.00%1100.00%
Total114100.00%1100.00%


static void mmf_recalc_uprobes(struct mm_struct *mm) { struct vm_area_struct *vma; for (vma = mm->mmap; vma; vma = vma->vm_next) { if (!valid_vma(vma, false)) continue; /* * This is not strictly accurate, we can race with * uprobe_unregister() and see the already removed * uprobe if delete_uprobe() was not yet called. * Or this uprobe can be filtered out. */ if (vma_has_uprobes(vma, vma->vm_start, vma->vm_end)) return; } clear_bit(MMF_HAS_UPROBES, &mm->flags); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov72100.00%2100.00%
Total72100.00%2100.00%


static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr) { struct page *page; uprobe_opcode_t opcode; int result; pagefault_disable(); result = __get_user(opcode, (uprobe_opcode_t __user *)vaddr); pagefault_enable(); if (likely(result == 0)) goto out; /* * The NULL 'tsk' here ensures that any faults that occur here * will not be accounted to the task. 'mm' *is* current->mm, * but we treat this as a 'remote' access since it is * essentially a kernel access to the memory. */ result = get_user_pages_remote(NULL, mm, vaddr, 1, FOLL_FORCE, &page, NULL, NULL); if (result < 0) return result; copy_from_page(page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE); put_page(page); out: /* This needs to return true for any variant of the trap insn */ return is_trap_insn(&opcode); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov10791.45%228.57%
Ananth N. Mavinakayanahalli32.56%114.29%
Lorenzo Stoakes32.56%228.57%
Linus Torvalds21.71%114.29%
Dave Hansen21.71%114.29%
Total117100.00%7100.00%


static struct uprobe *find_active_uprobe(unsigned long bp_vaddr, int *is_swbp) { struct mm_struct *mm = current->mm; struct uprobe *uprobe = NULL; struct vm_area_struct *vma; down_read(&mm->mmap_sem); vma = find_vma(mm, bp_vaddr); if (vma && vma->vm_start <= bp_vaddr) { if (valid_vma(vma, false)) { struct inode *inode = file_inode(vma->vm_file); loff_t offset = vaddr_to_offset(vma, bp_vaddr); uprobe = find_uprobe(inode, offset); } if (!uprobe) *is_swbp = is_trap_at_addr(mm, bp_vaddr); } else { *is_swbp = -EFAULT; } if (!uprobe && test_and_clear_bit(MMF_RECALC_UPROBES, &mm->flags)) mmf_recalc_uprobes(mm); up_read(&mm->mmap_sem); return uprobe; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov8652.76%675.00%
Srikar Dronamraju7646.63%112.50%
Ananth N. Mavinakayanahalli10.61%112.50%
Total163100.00%8100.00%


static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs) { struct uprobe_consumer *uc; int remove = UPROBE_HANDLER_REMOVE; bool need_prep = false; /* prepare return uprobe, when needed */ down_read(&uprobe->register_rwsem); for (uc = uprobe->consumers; uc; uc = uc->next) { int rc = 0; if (uc->handler) { rc = uc->handler(uc, regs); WARN(rc & ~UPROBE_HANDLER_MASK, "bad rc=0x%x from %pf()\n", rc, uc->handler); } if (uc->ret_handler) need_prep = true; remove &= rc; } if (need_prep && !remove) prepare_uretprobe(uprobe, regs); /* put bp at return */ if (remove && uprobe->consumers) { WARN_ON(!uprobe_is_active(uprobe)); unapply_uprobe(uprobe, current->mm); } up_read(&uprobe->register_rwsem); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov11973.01%133.33%
Anton Arapov4426.99%266.67%
Total163100.00%3100.00%


static void handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs) { struct uprobe *uprobe = ri->uprobe; struct uprobe_consumer *uc; down_read(&uprobe->register_rwsem); for (uc = uprobe->consumers; uc; uc = uc->next) { if (uc->ret_handler) uc->ret_handler(uc, ri->func, regs); } up_read(&uprobe->register_rwsem); }

Contributors

PersonTokensPropCommitsCommitProp
Anton Arapov83100.00%1100.00%
Total83100.00%1100.00%


static struct return_instance *find_next_ret_chain(struct return_instance *ri) { bool chained; do { chained = ri->chained; ri = ri->next; /* can't be NULL if chained */ } while (chained); return ri; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov40100.00%1100.00%
Total40100.00%1100.00%


static void handle_trampoline(struct pt_regs *regs) { struct uprobe_task *utask; struct return_instance *ri, *next; bool valid; utask = current->utask; if (!utask) goto sigill; ri = utask->return_instances; if (!ri) goto sigill; do { /* * We should throw out the frames invalidated by longjmp(). * If this chain is valid, then the next one should be alive * or NULL; the latter case means that nobody but ri->func * could hit this trampoline on return. TODO: sigaltstack(). */ next = find_next_ret_chain(ri); valid = !next || arch_uretprobe_is_alive(next, RP_CHECK_RET, regs); instruction_pointer_set(regs, ri->orig_ret_vaddr); do { if (valid) handle_uretprobe_chain(ri, regs); ri = free_ret_instance(ri); utask->depth--; } while (ri != next); } while (!valid); utask->return_instances = ri; return; sigill: uprobe_warn(current, "handle uretprobe, sending SIGILL."); force_sig_info(SIGILL, SEND_SIG_FORCED, current); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov8152.94%685.71%
Anton Arapov7247.06%114.29%
Total153100.00%7100.00%


bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs) { return false; }

Contributors

PersonTokensPropCommitsCommitProp
David A. Long19100.00%1100.00%
Total19100.00%1100.00%


bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, struct pt_regs *regs) { return true; }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov23100.00%2100.00%
Total23100.00%2100.00%

/* * Run handler and ask thread to singlestep. * Ensure all non-fatal signals cannot interrupt thread while it singlesteps. */
static void handle_swbp(struct pt_regs *regs) { struct uprobe *uprobe; unsigned long bp_vaddr; int uninitialized_var(is_swbp); bp_vaddr = uprobe_get_swbp_addr(regs); if (bp_vaddr == get_trampoline_vaddr()) return handle_trampoline(regs); uprobe = find_active_uprobe(bp_vaddr, &is_swbp); if (!uprobe) { if (is_swbp > 0) { /* No matching uprobe; signal SIGTRAP. */ send_sig(SIGTRAP, current, 0); } else { /* * Either we raced with uprobe_unregister() or we can't * access this memory. The latter is only possible if * another thread plays with our ->mm. In both cases * we can simply restart. If this vma was unmapped we * can pretend this insn was not executed yet and get * the (correct) SIGSEGV after restart. */ instruction_pointer_set(regs, bp_vaddr); } return; } /* change it in advance for ->handler() and restart */ instruction_pointer_set(regs, bp_vaddr); /* * TODO: move copy_insn/etc into _register and remove this hack. * After we hit the bp, _unregister + _register can install the * new and not-yet-analyzed uprobe at the same address, restart. */ smp_rmb(); /* pairs with wmb() in install_breakpoint() */ if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags))) goto out; /* Tracing handlers use ->utask to communicate with fetch methods */ if (!get_utask()) goto out; if (arch_uprobe_ignore(&uprobe->arch, regs)) goto out; handler_chain(uprobe, regs); if (arch_uprobe_skip_sstep(&uprobe->arch, regs)) goto out; if (!pre_ssout(uprobe, regs, bp_vaddr)) return; /* arch_uprobe_skip_sstep() succeeded, or restart if can't singlestep */ out: put_uprobe(uprobe); }

Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov11459.07%1178.57%
Srikar Dronamraju5327.46%17.14%
David A. Long157.77%17.14%
Anton Arapov115.70%17.14%
Total193100.00%14100.00%

/* * Perform required fix-ups and disable singlestep. * Allow pending signals to take effect. */
static void handle_singlestep(struct uprobe_task *utask, struct pt_regs *regs) { struct uprobe *uprobe; int err = 0; uprobe = utask->active_uprobe; if (utask->state == UTASK_SSTEP_ACK) err = arch_uprobe_post_xol(&uprobe->arch, regs); else if (utask->state == UTASK_SSTEP_TRAPPED) arch_uprobe_abort_xol(&uprobe->arch, regs); else WARN_ON_ONCE(1); put_uprobe(uprobe); utask->active_uprobe = NULL; utask->state = UTASK_RUNNING; xol_free_insn_slot(current); spin_lock_irq(&current->sighand->siglock); recalc_sigpending(); /* see uprobe_deny_signal() */ spin_unlock_irq(&current->sighand->siglock); if (unlikely(err)) { uprobe_warn(current, "execute the probed insn, sending SIGILL."); force_sig_info(SIGILL, SEND_SIG_FORCED, current); } }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju11577.70%250.00%
Oleg Nesterov3221.62%125.00%
Sebastian Andrzej Siewior10.68%125.00%
Total148100.00%4100.00%

/* * On breakpoint hit, breakpoint notifier sets the TIF_UPROBE flag and * allows the thread to return from interrupt. After that handle_swbp() * sets utask->active_uprobe. * * On singlestep exception, singlestep notifier sets the TIF_UPROBE flag * and allows the thread to return from interrupt. * * While returning to userspace, thread notices the TIF_UPROBE flag and calls * uprobe_notify_resume(). */
void uprobe_notify_resume(struct pt_regs *regs) { struct uprobe_task *utask; clear_thread_flag(TIF_UPROBE); utask = current->utask; if (utask && utask->active_uprobe) handle_singlestep(utask, regs); else handle_swbp(regs); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju3676.60%133.33%
Oleg Nesterov1123.40%266.67%
Total47100.00%3100.00%

/* * uprobe_pre_sstep_notifier gets called from interrupt context as part of * notifier mechanism. Set TIF_UPROBE flag and indicate breakpoint hit. */
int uprobe_pre_sstep_notifier(struct pt_regs *regs) { if (!current->mm) return 0; if (!test_bit(MMF_HAS_UPROBES, &current->mm->flags) && (!current->utask || !current->utask->return_instances)) return 0; set_thread_flag(TIF_UPROBE); return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju2846.67%133.33%
Anton Arapov2033.33%133.33%
Oleg Nesterov1220.00%133.33%
Total60100.00%3100.00%

/* * uprobe_post_sstep_notifier gets called in interrupt context as part of notifier * mechanism. Set TIF_UPROBE flag and indicate completion of singlestep. */
int uprobe_post_sstep_notifier(struct pt_regs *regs) { struct uprobe_task *utask = current->utask; if (!current->mm || !utask || !utask->active_uprobe) /* task is currently not uprobed */ return 0; utask->state = UTASK_SSTEP_ACK; set_thread_flag(TIF_UPROBE); return 1; }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju52100.00%1100.00%
Total52100.00%1100.00%

static struct notifier_block uprobe_exception_nb = { .notifier_call = arch_uprobe_exception_notify, .priority = INT_MAX-1, /* notified after kprobes, kgdb */ };
static int __init init_uprobes(void) { int i; for (i = 0; i < UPROBES_HASH_SZ; i++) mutex_init(&uprobes_mmap_mutex[i]); if (percpu_init_rwsem(&dup_mmap_sem)) return -ENOMEM; return register_die_notifier(&uprobe_exception_nb); }

Contributors

PersonTokensPropCommitsCommitProp
Srikar Dronamraju4177.36%150.00%
Oleg Nesterov1222.64%150.00%
Total53100.00%2100.00%

__initcall(init_uprobes);

Overall Contributors

PersonTokensPropCommitsCommitProp
Oleg Nesterov392847.95%11672.50%
Srikar Dronamraju339141.39%95.62%
Anton Arapov5466.67%53.12%
Kirill A. Shutemov720.88%53.12%
Victor Kamensky420.51%10.62%
Johannes Weiner410.50%10.62%
Haggai Eran350.43%10.62%
David A. Long340.42%10.62%
Ingo Molnar270.33%31.88%
Ananth N. Mavinakayanahalli240.29%21.25%
Michal Hocko140.17%10.62%
Josh Stone130.16%10.62%
Lorenzo Stoakes60.07%21.25%
Dave Hansen30.04%10.62%
Jerome Marchand30.04%10.62%
Davidlohr Bueso A30.04%21.25%
Sebastian Andrzej Siewior30.04%21.25%
Linus Torvalds20.02%10.62%
Marcin Nowakowski10.01%10.62%
Michel Lespinasse10.01%10.62%
Joerg Roedel10.01%10.62%
Peter Zijlstra10.01%10.62%
Vegard Nossum10.01%10.62%
Total8192100.00%160100.00%
Directory: kernel/events
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.