// SPDX-License-Identifier: GPL-2.0+
|
/*
|
* User-space Probes (UProbes)
|
*
|
* 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>
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#include <linux/sched/mm.h>
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#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 */
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#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>
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#include <linux/khugepaged.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])
|
|
DEFINE_STATIC_PERCPU_RWSEM(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 */
|
refcount_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;
|
loff_t ref_ctr_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;
|
};
|
|
struct delayed_uprobe {
|
struct list_head list;
|
struct uprobe *uprobe;
|
struct mm_struct *mm;
|
};
|
|
static DEFINE_MUTEX(delayed_uprobe_lock);
|
static LIST_HEAD(delayed_uprobe_list);
|
|
/*
|
* 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.
|
*/
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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;
|
}
|
|
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);
|
}
|
|
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);
|
}
|
|
/**
|
* __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
|
* @old_page: the page we are replacing by new_page
|
* @new_page: the modified page we replace page by
|
*
|
* If @new_page is NULL, only unmap @old_page.
|
*
|
* Returns 0 on success, negative error code otherwise.
|
*/
|
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;
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struct page_vma_mapped_walk pvmw = {
|
.page = compound_head(old_page),
|
.vma = vma,
|
.address = addr,
|
};
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int err;
|
struct mmu_notifier_range range;
|
|
mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, addr,
|
addr + PAGE_SIZE);
|
|
if (new_page) {
|
err = mem_cgroup_charge(new_page, vma->vm_mm, GFP_KERNEL);
|
if (err)
|
return err;
|
}
|
|
/* For try_to_free_swap() and munlock_vma_page() below */
|
lock_page(old_page);
|
|
mmu_notifier_invalidate_range_start(&range);
|
err = -EAGAIN;
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if (!page_vma_mapped_walk(&pvmw))
|
goto unlock;
|
VM_BUG_ON_PAGE(addr != pvmw.address, old_page);
|
|
if (new_page) {
|
get_page(new_page);
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page_add_new_anon_rmap(new_page, vma, addr, false);
|
lru_cache_add_inactive_or_unevictable(new_page, vma);
|
} else
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/* no new page, just dec_mm_counter for old_page */
|
dec_mm_counter(mm, MM_ANONPAGES);
|
|
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);
|
if (new_page)
|
set_pte_at_notify(mm, addr, pvmw.pte,
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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);
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page_vma_mapped_walk_done(&pvmw);
|
|
if ((vma->vm_flags & VM_LOCKED) && !PageCompound(old_page))
|
munlock_vma_page(old_page);
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put_page(old_page);
|
|
err = 0;
|
unlock:
|
mmu_notifier_invalidate_range_end(&range);
|
unlock_page(old_page);
|
return err;
|
}
|
|
/**
|
* 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;
|
}
|
|
/**
|
* 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);
|
}
|
|
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);
|
}
|
|
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);
|
}
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|
static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t *new_opcode)
|
{
|
uprobe_opcode_t old_opcode;
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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.
|
*/
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copy_from_page(page, vaddr, &old_opcode, UPROBE_SWBP_INSN_SIZE);
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is_swbp = is_swbp_insn(&old_opcode);
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|
if (is_swbp_insn(new_opcode)) {
|
if (is_swbp) /* register: already installed? */
|
return 0;
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} else {
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if (!is_swbp) /* unregister: was it changed by us? */
|
return 0;
|
}
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|
return 1;
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}
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|
static struct delayed_uprobe *
|
delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm)
|
{
|
struct delayed_uprobe *du;
|
|
list_for_each_entry(du, &delayed_uprobe_list, list)
|
if (du->uprobe == uprobe && du->mm == mm)
|
return du;
|
return NULL;
|
}
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|
static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm)
|
{
|
struct delayed_uprobe *du;
|
|
if (delayed_uprobe_check(uprobe, mm))
|
return 0;
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|
du = kzalloc(sizeof(*du), GFP_KERNEL);
|
if (!du)
|
return -ENOMEM;
|
|
du->uprobe = uprobe;
|
du->mm = mm;
|
list_add(&du->list, &delayed_uprobe_list);
|
return 0;
|
}
|
|
static void delayed_uprobe_delete(struct delayed_uprobe *du)
|
{
|
if (WARN_ON(!du))
|
return;
|
list_del(&du->list);
|
kfree(du);
|
}
|
|
static void delayed_uprobe_remove(struct uprobe *uprobe, struct mm_struct *mm)
|
{
|
struct list_head *pos, *q;
|
struct delayed_uprobe *du;
|
|
if (!uprobe && !mm)
|
return;
|
|
list_for_each_safe(pos, q, &delayed_uprobe_list) {
|
du = list_entry(pos, struct delayed_uprobe, list);
|
|
if (uprobe && du->uprobe != uprobe)
|
continue;
|
if (mm && du->mm != mm)
|
continue;
|
|
delayed_uprobe_delete(du);
|
}
|
}
|
|
static bool valid_ref_ctr_vma(struct uprobe *uprobe,
|
struct vm_area_struct *vma)
|
{
|
unsigned long vaddr = offset_to_vaddr(vma, uprobe->ref_ctr_offset);
|
|
return uprobe->ref_ctr_offset &&
|
vma->vm_file &&
|
file_inode(vma->vm_file) == uprobe->inode &&
|
(vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE &&
|
vma->vm_start <= vaddr &&
|
vma->vm_end > vaddr;
|
}
|
|
static struct vm_area_struct *
|
find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm)
|
{
|
struct vm_area_struct *tmp;
|
|
for (tmp = mm->mmap; tmp; tmp = tmp->vm_next)
|
if (valid_ref_ctr_vma(uprobe, tmp))
|
return tmp;
|
|
return NULL;
|
}
|
|
static int
|
__update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d)
|
{
|
void *kaddr;
|
struct page *page;
|
struct vm_area_struct *vma;
|
int ret;
|
short *ptr;
|
|
if (!vaddr || !d)
|
return -EINVAL;
|
|
ret = get_user_pages_remote(mm, vaddr, 1,
|
FOLL_WRITE, &page, &vma, NULL);
|
if (unlikely(ret <= 0)) {
|
/*
|
* We are asking for 1 page. If get_user_pages_remote() fails,
|
* it may return 0, in that case we have to return error.
|
*/
|
return ret == 0 ? -EBUSY : ret;
|
}
|
|
kaddr = kmap_atomic(page);
|
ptr = kaddr + (vaddr & ~PAGE_MASK);
|
|
if (unlikely(*ptr + d < 0)) {
|
pr_warn("ref_ctr going negative. vaddr: 0x%lx, "
|
"curr val: %d, delta: %d\n", vaddr, *ptr, d);
|
ret = -EINVAL;
|
goto out;
|
}
|
|
*ptr += d;
|
ret = 0;
|
out:
|
kunmap_atomic(kaddr);
|
put_page(page);
|
return ret;
|
}
|
|
static void update_ref_ctr_warn(struct uprobe *uprobe,
|
struct mm_struct *mm, short d)
|
{
|
pr_warn("ref_ctr %s failed for inode: 0x%lx offset: "
|
"0x%llx ref_ctr_offset: 0x%llx of mm: 0x%pK\n",
|
d > 0 ? "increment" : "decrement", uprobe->inode->i_ino,
|
(unsigned long long) uprobe->offset,
|
(unsigned long long) uprobe->ref_ctr_offset, mm);
|
}
|
|
static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm,
|
short d)
|
{
|
struct vm_area_struct *rc_vma;
|
unsigned long rc_vaddr;
|
int ret = 0;
|
|
rc_vma = find_ref_ctr_vma(uprobe, mm);
|
|
if (rc_vma) {
|
rc_vaddr = offset_to_vaddr(rc_vma, uprobe->ref_ctr_offset);
|
ret = __update_ref_ctr(mm, rc_vaddr, d);
|
if (ret)
|
update_ref_ctr_warn(uprobe, mm, d);
|
|
if (d > 0)
|
return ret;
|
}
|
|
mutex_lock(&delayed_uprobe_lock);
|
if (d > 0)
|
ret = delayed_uprobe_add(uprobe, mm);
|
else
|
delayed_uprobe_remove(uprobe, mm);
|
mutex_unlock(&delayed_uprobe_lock);
|
|
return ret;
|
}
|
|
/*
|
* 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_lock held for write.
|
* Return 0 (success) or a negative errno.
|
*/
|
int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,
|
unsigned long vaddr, uprobe_opcode_t opcode)
|
{
|
struct uprobe *uprobe;
|
struct page *old_page, *new_page;
|
struct vm_area_struct *vma;
|
int ret, is_register, ref_ctr_updated = 0;
|
bool orig_page_huge = false;
|
unsigned int gup_flags = FOLL_FORCE;
|
|
is_register = is_swbp_insn(&opcode);
|
uprobe = container_of(auprobe, struct uprobe, arch);
|
|
retry:
|
if (is_register)
|
gup_flags |= FOLL_SPLIT_PMD;
|
/* Read the page with vaddr into memory */
|
ret = get_user_pages_remote(mm, vaddr, 1, gup_flags,
|
&old_page, &vma, NULL);
|
if (ret <= 0)
|
return ret;
|
|
ret = verify_opcode(old_page, vaddr, &opcode);
|
if (ret <= 0)
|
goto put_old;
|
|
if (WARN(!is_register && PageCompound(old_page),
|
"uprobe unregister should never work on compound page\n")) {
|
ret = -EINVAL;
|
goto put_old;
|
}
|
|
/* We are going to replace instruction, update ref_ctr. */
|
if (!ref_ctr_updated && uprobe->ref_ctr_offset) {
|
ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1);
|
if (ret)
|
goto put_old;
|
|
ref_ctr_updated = 1;
|
}
|
|
ret = 0;
|
if (!is_register && !PageAnon(old_page))
|
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);
|
|
if (!is_register) {
|
struct page *orig_page;
|
pgoff_t index;
|
|
VM_BUG_ON_PAGE(!PageAnon(old_page), old_page);
|
|
index = vaddr_to_offset(vma, vaddr & PAGE_MASK) >> PAGE_SHIFT;
|
orig_page = find_get_page(vma->vm_file->f_inode->i_mapping,
|
index);
|
|
if (orig_page) {
|
if (PageUptodate(orig_page) &&
|
pages_identical(new_page, orig_page)) {
|
/* let go new_page */
|
put_page(new_page);
|
new_page = NULL;
|
|
if (PageCompound(orig_page))
|
orig_page_huge = true;
|
}
|
put_page(orig_page);
|
}
|
}
|
|
ret = __replace_page(vma, vaddr, old_page, new_page);
|
if (new_page)
|
put_page(new_page);
|
put_old:
|
put_page(old_page);
|
|
if (unlikely(ret == -EAGAIN))
|
goto retry;
|
|
/* Revert back reference counter if instruction update failed. */
|
if (ret && is_register && ref_ctr_updated)
|
update_ref_ctr(uprobe, mm, -1);
|
|
/* try collapse pmd for compound page */
|
if (!ret && orig_page_huge)
|
collapse_pte_mapped_thp(mm, vaddr);
|
|
return ret;
|
}
|
|
/**
|
* 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(auprobe, mm, vaddr, UPROBE_SWBP_INSN);
|
}
|
|
/**
|
* 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(auprobe, mm, vaddr,
|
*(uprobe_opcode_t *)&auprobe->insn);
|
}
|
|
static struct uprobe *get_uprobe(struct uprobe *uprobe)
|
{
|
refcount_inc(&uprobe->ref);
|
return uprobe;
|
}
|
|
static void put_uprobe(struct uprobe *uprobe)
|
{
|
if (refcount_dec_and_test(&uprobe->ref)) {
|
/*
|
* If application munmap(exec_vma) before uprobe_unregister()
|
* gets called, we don't get a chance to remove uprobe from
|
* delayed_uprobe_list from remove_breakpoint(). Do it here.
|
*/
|
mutex_lock(&delayed_uprobe_lock);
|
delayed_uprobe_remove(uprobe, NULL);
|
mutex_unlock(&delayed_uprobe_lock);
|
kfree(uprobe);
|
}
|
}
|
|
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;
|
}
|
|
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;
|
}
|
|
/*
|
* 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;
|
}
|
|
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 */
|
refcount_set(&uprobe->ref, 2);
|
|
return u;
|
}
|
|
/*
|
* 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;
|
}
|
|
static void
|
ref_ctr_mismatch_warn(struct uprobe *cur_uprobe, struct uprobe *uprobe)
|
{
|
pr_warn("ref_ctr_offset mismatch. inode: 0x%lx offset: 0x%llx "
|
"ref_ctr_offset(old): 0x%llx ref_ctr_offset(new): 0x%llx\n",
|
uprobe->inode->i_ino, (unsigned long long) uprobe->offset,
|
(unsigned long long) cur_uprobe->ref_ctr_offset,
|
(unsigned long long) uprobe->ref_ctr_offset);
|
}
|
|
static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset,
|
loff_t ref_ctr_offset)
|
{
|
struct uprobe *uprobe, *cur_uprobe;
|
|
uprobe = kzalloc(sizeof(struct uprobe), GFP_KERNEL);
|
if (!uprobe)
|
return NULL;
|
|
uprobe->inode = inode;
|
uprobe->offset = offset;
|
uprobe->ref_ctr_offset = ref_ctr_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) {
|
if (cur_uprobe->ref_ctr_offset != uprobe->ref_ctr_offset) {
|
ref_ctr_mismatch_warn(cur_uprobe, uprobe);
|
put_uprobe(cur_uprobe);
|
kfree(uprobe);
|
return ERR_PTR(-EINVAL);
|
}
|
kfree(uprobe);
|
uprobe = cur_uprobe;
|
}
|
|
return uprobe;
|
}
|
|
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);
|
}
|
|
/*
|
* 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;
|
}
|
|
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;
|
}
|
|
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;
|
}
|
|
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;
|
|
smp_wmb(); /* pairs with the smp_rmb() in handle_swbp() */
|
set_bit(UPROBE_COPY_INSN, &uprobe->flags);
|
|
out:
|
up_write(&uprobe->consumer_rwsem);
|
|
return ret;
|
}
|
|
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);
|
}
|
|
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;
|
}
|
|
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;
|
}
|
|
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);
|
}
|
|
static inline bool uprobe_is_active(struct uprobe *uprobe)
|
{
|
return !RB_EMPTY_NODE(&uprobe->rb_node);
|
}
|
/*
|
* 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() */
|
put_uprobe(uprobe);
|
}
|
|
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;
|
}
|
|
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;
|
}
|
|
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;
|
|
mmap_write_lock(mm);
|
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:
|
mmap_write_unlock(mm);
|
free:
|
mmput(mm);
|
info = free_map_info(info);
|
}
|
out:
|
percpu_up_write(&dup_mmap_sem);
|
return err;
|
}
|
|
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);
|
}
|
|
/*
|
* uprobe_unregister - unregister an 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);
|
}
|
EXPORT_SYMBOL_GPL(uprobe_unregister);
|
|
/*
|
* __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. Caller of __uprobe_register() is required to keep @inode
|
* (and the containing mount) referenced.
|
*
|
* Return errno if it cannot successully install probes
|
* else return 0 (success)
|
*/
|
static int __uprobe_register(struct inode *inode, loff_t offset,
|
loff_t ref_ctr_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;
|
|
/*
|
* This ensures that copy_from_page(), copy_to_page() and
|
* __update_ref_ctr() can't cross page boundary.
|
*/
|
if (!IS_ALIGNED(offset, UPROBE_SWBP_INSN_SIZE))
|
return -EINVAL;
|
if (!IS_ALIGNED(ref_ctr_offset, sizeof(short)))
|
return -EINVAL;
|
|
retry:
|
uprobe = alloc_uprobe(inode, offset, ref_ctr_offset);
|
if (!uprobe)
|
return -ENOMEM;
|
if (IS_ERR(uprobe))
|
return PTR_ERR(uprobe);
|
|
/*
|
* 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))) {
|
consumer_add(uprobe, uc);
|
ret = register_for_each_vma(uprobe, uc);
|
if (ret)
|
__uprobe_unregister(uprobe, uc);
|
}
|
up_write(&uprobe->register_rwsem);
|
put_uprobe(uprobe);
|
|
if (unlikely(ret == -EAGAIN))
|
goto retry;
|
return ret;
|
}
|
|
int uprobe_register(struct inode *inode, loff_t offset,
|
struct uprobe_consumer *uc)
|
{
|
return __uprobe_register(inode, offset, 0, uc);
|
}
|
EXPORT_SYMBOL_GPL(uprobe_register);
|
|
int uprobe_register_refctr(struct inode *inode, loff_t offset,
|
loff_t ref_ctr_offset, struct uprobe_consumer *uc)
|
{
|
return __uprobe_register(inode, offset, ref_ctr_offset, uc);
|
}
|
EXPORT_SYMBOL_GPL(uprobe_register_refctr);
|
|
/*
|
* uprobe_apply - unregister an 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;
|
}
|
|
static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
|
{
|
struct vm_area_struct *vma;
|
int err = 0;
|
|
mmap_read_lock(mm);
|
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);
|
}
|
mmap_read_unlock(mm);
|
|
return err;
|
}
|
|
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;
|
}
|
|
/*
|
* 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);
|
}
|
|
/* @vma contains reference counter, not the probed instruction. */
|
static int delayed_ref_ctr_inc(struct vm_area_struct *vma)
|
{
|
struct list_head *pos, *q;
|
struct delayed_uprobe *du;
|
unsigned long vaddr;
|
int ret = 0, err = 0;
|
|
mutex_lock(&delayed_uprobe_lock);
|
list_for_each_safe(pos, q, &delayed_uprobe_list) {
|
du = list_entry(pos, struct delayed_uprobe, list);
|
|
if (du->mm != vma->vm_mm ||
|
!valid_ref_ctr_vma(du->uprobe, vma))
|
continue;
|
|
vaddr = offset_to_vaddr(vma, du->uprobe->ref_ctr_offset);
|
ret = __update_ref_ctr(vma->vm_mm, vaddr, 1);
|
if (ret) {
|
update_ref_ctr_warn(du->uprobe, vma->vm_mm, 1);
|
if (!err)
|
err = ret;
|
}
|
delayed_uprobe_delete(du);
|
}
|
mutex_unlock(&delayed_uprobe_lock);
|
return err;
|
}
|
|
/*
|
* Called from mmap_region/vma_adjust with mm->mmap_lock 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())
|
return 0;
|
|
if (vma->vm_file &&
|
(vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE &&
|
test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags))
|
delayed_ref_ctr_inc(vma);
|
|
if (!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;
|
}
|
|
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;
|
}
|
|
/*
|
* 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);
|
}
|
|
/* 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 (mmap_write_lock_killable(mm))
|
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 (IS_ERR_VALUE(area->vaddr)) {
|
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;
|
/* pairs with get_xol_area() */
|
smp_store_release(&mm->uprobes_state.xol_area, area); /* ^^^ */
|
fail:
|
mmap_write_unlock(mm);
|
|
return ret;
|
}
|
|
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 = kcalloc(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;
|
}
|
|
/*
|
* 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);
|
|
/* Pairs with xol_add_vma() smp_store_release() */
|
area = READ_ONCE(mm->uprobes_state.xol_area); /* ^^^ */
|
return area;
|
}
|
|
/*
|
* 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;
|
|
mutex_lock(&delayed_uprobe_lock);
|
delayed_uprobe_remove(NULL, mm);
|
mutex_unlock(&delayed_uprobe_lock);
|
|
if (!area)
|
return;
|
|
put_page(area->pages[0]);
|
kfree(area->bitmap);
|
kfree(area);
|
}
|
|
void uprobe_start_dup_mmap(void)
|
{
|
percpu_down_read(&dup_mmap_sem);
|
}
|
|
void uprobe_end_dup_mmap(void)
|
{
|
percpu_up_read(&dup_mmap_sem);
|
}
|
|
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);
|
}
|
}
|
|
/*
|
* - 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;
|
}
|
|
/*
|
* 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;
|
}
|
|
/*
|
* 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;
|
}
|
}
|
|
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_page() 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);
|
}
|
|
/**
|
* 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;
|
}
|
|
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);
|
}
|
|
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;
|
}
|
|
/*
|
* Called with no locks held.
|
* Called in context of an exiting or an 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;
|
}
|
|
/*
|
* Allocate a uprobe_task object for the task 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;
|
}
|
|
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;
|
}
|
|
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);
|
}
|
|
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");
|
}
|
|
/*
|
* 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, TWA_RESUME);
|
}
|
|
/*
|
* 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;
|
|
/* Pairs with xol_add_vma() smp_store_release() */
|
area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */
|
if (area)
|
trampoline_vaddr = area->vaddr;
|
|
return trampoline_vaddr;
|
}
|
|
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;
|
}
|
|
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);
|
}
|
|
/* 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;
|
}
|
|
/*
|
* 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 (task_sigpending(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;
|
}
|
|
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);
|
}
|
|
static int is_trap_at_addr(struct mm_struct *mm, unsigned long vaddr)
|
{
|
struct page *page;
|
uprobe_opcode_t opcode;
|
int result;
|
|
if (WARN_ON_ONCE(!IS_ALIGNED(vaddr, UPROBE_SWBP_INSN_SIZE)))
|
return -EINVAL;
|
|
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(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);
|
}
|
|
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;
|
|
mmap_read_lock(mm);
|
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);
|
mmap_read_unlock(mm);
|
|
return uprobe;
|
}
|
|
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 %ps()\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);
|
}
|
|
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);
|
}
|
|
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;
|
}
|
|
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(SIGILL);
|
|
}
|
|
bool __weak arch_uprobe_ignore(struct arch_uprobe *aup, struct pt_regs *regs)
|
{
|
return false;
|
}
|
|
bool __weak arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
|
struct pt_regs *regs)
|
{
|
return true;
|
}
|
|
/*
|
* 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 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. */
|
force_sig(SIGTRAP);
|
} 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.
|
*/
|
if (unlikely(!test_bit(UPROBE_COPY_INSN, &uprobe->flags)))
|
goto out;
|
|
/*
|
* Pairs with the smp_wmb() in prepare_uprobe().
|
*
|
* Guarantees that if we see the UPROBE_COPY_INSN bit set, then
|
* we must also see the stores to &uprobe->arch performed by the
|
* prepare_uprobe() call.
|
*/
|
smp_rmb();
|
|
/* 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);
|
}
|
|
/*
|
* 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(¤t->sighand->siglock);
|
recalc_sigpending(); /* see uprobe_deny_signal() */
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
if (unlikely(err)) {
|
uprobe_warn(current, "execute the probed insn, sending SIGILL.");
|
force_sig(SIGILL);
|
}
|
}
|
|
/*
|
* 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);
|
}
|
|
/*
|
* 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, ¤t->mm->flags) &&
|
(!current->utask || !current->utask->return_instances))
|
return 0;
|
|
set_thread_flag(TIF_UPROBE);
|
return 1;
|
}
|
|
/*
|
* 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;
|
}
|
|
static struct notifier_block uprobe_exception_nb = {
|
.notifier_call = arch_uprobe_exception_notify,
|
.priority = INT_MAX-1, /* notified after kprobes, kgdb */
|
};
|
|
void __init uprobes_init(void)
|
{
|
int i;
|
|
for (i = 0; i < UPROBES_HASH_SZ; i++)
|
mutex_init(&uprobes_mmap_mutex[i]);
|
|
BUG_ON(register_die_notifier(&uprobe_exception_nb));
|
}
|
