/*
* Userspace 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, 2008-2011
* Authors:
* Srikar Dronamraju
* Jim Keniston
*/
#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/rmap.h> /* anon_vma_prepare */
#include <linux/mmu_notifier.h> /* set_pte_at_notify */
#include <linux/swap.h> /* try_to_free_swap */
#include <linux/uprobes.h>
static struct rb_root uprobes_tree = RB_ROOT;
static DEFINE_SPINLOCK(uprobes_treelock); /* serialize rbtree access */
#define UPROBES_HASH_SZ 13
/* serialize (un)register */
static struct mutex uprobes_mutex[UPROBES_HASH_SZ];
#define uprobes_hash(v) (&uprobes_mutex[((unsigned long)(v)) %\
UPROBES_HASH_SZ])
/* 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])
/*
* uprobe_events allows us to skip the mmap_uprobe if there are no uprobe
* events active at this time. Probably a fine grained per inode count is
* better?
*/
static atomic_t uprobe_events = ATOMIC_INIT(0);
/*
* Maintain a temporary per vma info that can be used to search if a vma
* has already been handled. This structure is introduced since extending
* vm_area_struct wasnt recommended.
*/
struct vma_info {
struct list_head probe_list;
struct mm_struct *mm;
loff_t vaddr;
};
/*
* 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)
{
if (!vma->vm_file)
return false;
if (!is_register)
return true;
if ((vma->vm_flags & (VM_READ|VM_WRITE|VM_EXEC|VM_SHARED)) ==
(VM_READ|VM_EXEC))
return true;
return false;
}
static loff_t vma_address(struct vm_area_struct *vma, loff_t offset)
{
loff_t vaddr;
vaddr = vma->vm_start + offset;
vaddr -= vma->vm_pgoff << PAGE_SHIFT;
return vaddr;
}
/**
* __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
* @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, struct page *page,
struct page *kpage)
{
struct mm_struct *mm = vma->vm_mm;
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *ptep;
spinlock_t *ptl;
unsigned long addr;
int err = -EFAULT;
addr = page_address_in_vma(page, vma);
if (addr == -EFAULT)
goto out;
pgd = pgd_offset(mm, addr);
if (!pgd_present(*pgd))
goto out;
pud = pud_offset(pgd, addr);
if (!pud_present(*pud))
goto out;
pmd = pmd_offset(pud, addr);
if (!pmd_present(*pmd))
goto out;
ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
if (!ptep)
goto out;
get_page(kpage);
page_add_new_anon_rmap(kpage, vma, addr);
flush_cache_page(vma, addr, pte_pfn(*ptep));
ptep_clear_flush(vma, addr, ptep);
set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
page_remove_rmap(page);
if (!page_mapped(page))
try_to_free_swap(page);
put_page(page);
pte_unmap_unlock(ptep, ptl);
err = 0;
out:
return err;
}
/**
* is_bkpt_insn - check if instruction is breakpoint instruction.
* @insn: instruction to be checked.
* Default implementation of is_bkpt_insn
* Returns true if @insn is a breakpoint instruction.
*/
bool __weak is_bkpt_insn(uprobe_opcode_t *insn)
{
return (*insn == UPROBES_BKPT_INSN);
}
/*
* 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 read_opcode /
* write_opcode accordingly. This would never be a problem for archs that
* have fixed length instructions.
*/
/*
* write_opcode - write the opcode at a given virtual address.
* @mm: the probed process address space.
* @uprobe: the breakpointing information.
* @vaddr: the virtual address to store the opcode.
* @opcode: opcode to be written at @vaddr.
*
* Called with mm->mmap_sem held (for read and with a reference to
* mm).
*
* For mm @mm, write the opcode at @vaddr.
* Return 0 (success) or a negative errno.
*/
static int write_opcode(struct mm_struct *mm, struct uprobe *uprobe,
unsigned long vaddr, uprobe_opcode_t opcode)
{
struct page *old_page, *new_page;
struct address_space *mapping;
void *vaddr_old, *vaddr_new;
struct vm_area_struct *vma;
loff_t addr;
int ret;
/* Read the page with vaddr into memory */
ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &old_page, &vma);
if (ret <= 0)
return ret;
ret = -EINVAL;
/*
* We are interested in text pages only. Our pages of interest
* should be mapped for read and execute only. We desist from
* adding probes in write mapped pages since the breakpoints
* might end up in the file copy.
*/
if (!valid_vma(vma, is_bkpt_insn(&opcode)))
goto put_out;
mapping = uprobe->inode->i_mapping;
if (mapping != vma->vm_file->f_mapping)
goto put_out;
addr = vma_address(vma, uprobe->offset);
if (vaddr != (unsigned long)addr)
goto put_out;
ret = -ENOMEM;
new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
if (!new_page)
goto put_out;
__SetPageUptodate(new_page);
/*
* lock page will serialize against do_wp_page()'s
* PageAnon() handling
*/
lock_page(old_page);
/* copy the page now that we've got it stable */
vaddr_old = kmap_atomic(old_page);
vaddr_new = kmap_atomic(new_page);
memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
/* poke the new insn in, ASSUMES we don't cross page boundary */
vaddr &= ~PAGE_MASK;
BUG_ON(vaddr + uprobe_opcode_sz > PAGE_SIZE);
memcpy(vaddr_new + vaddr, &opcode, uprobe_opcode_sz);
kunmap_atomic(vaddr_new);
kunmap_atomic(vaddr_old);
ret = anon_vma_prepare(vma);
if (ret)
goto unlock_out;
lock_page(new_page);
ret = __replace_page(vma, old_page, new_page);
unlock_page(new_page);
unlock_out:
unlock_page(old_page);
page_cache_release(new_page);
put_out:
put_page(old_page); /* we did a get_page in the beginning */
return ret;
}
/**
* read_opcode - read the opcode at a given virtual address.
* @mm: the probed process address space.
* @vaddr: the virtual address to read the opcode.
* @opcode: location to store the read opcode.
*
* Called with mm->mmap_sem held (for read and with a reference to
* mm.
*
* For mm @mm, read the opcode at @vaddr and store it in @opcode.
* Return 0 (success) or a negative errno.
*/
static int read_opcode(struct mm_struct *mm, unsigned long vaddr,
uprobe_opcode_t *opcode)
{
struct page *page;
void *vaddr_new;
int ret;
ret = get_user_pages(NULL, mm, vaddr, 1, 0, 0, &page, NULL);
if (ret <= 0)
return ret;
lock_page(page);
vaddr_new = kmap_atomic(page);
vaddr &= ~PAGE_MASK;
memcpy(opcode, vaddr_new + vaddr, uprobe_opcode_sz);
kunmap_atomic(vaddr_new);
unlock_page(page);
put_page(page); /* we did a get_user_pages in the beginning */
return 0;
}
static int is_bkpt_at_addr(struct mm_struct *mm, unsigned long vaddr)
{
uprobe_opcode_t opcode;
int result = read_opcode(mm, vaddr, &opcode);
if (result)
return result;
if (is_bkpt_insn(&opcode))
return 1;
return 0;
}
/**
* set_bkpt - store breakpoint at a given address.
* @mm: the probed process address space.
* @uprobe: the probepoint information.
* @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_bkpt(struct mm_struct *mm, struct uprobe *uprobe,
unsigned long vaddr)
{
int result = is_bkpt_at_addr(mm, vaddr);
if (result == 1)
return -EEXIST;
if (result)
return result;
return write_opcode(mm, uprobe, vaddr, UPROBES_BKPT_INSN);
}
/**
* set_orig_insn - Restore the original instruction.
* @mm: the probed process address space.
* @uprobe: the probepoint information.
* @vaddr: the virtual address to insert the opcode.
* @verify: if true, verify existance of breakpoint instruction.
*
* For mm @mm, restore the original opcode (opcode) at @vaddr.
* Return 0 (success) or a negative errno.
*/
int __weak set_orig_insn(struct mm_struct *mm, struct uprobe *uprobe,
unsigned long vaddr, bool verify)
{
if (verify) {
int result = is_bkpt_at_addr(mm, vaddr);
if (!result)
return -EINVAL;
if (result != 1)
return result;
}
return write_opcode(mm, uprobe, vaddr,
*(uprobe_opcode_t *)uprobe->insn);
}
static int match_uprobe(struct uprobe *l, struct uprobe *r)
{
if (l->inode < r->inode)
return -1;
if (l->inode > r->inode)
return 1;
else {
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) {
atomic_inc(&uprobe->ref);
return 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;
unsigned long flags;
spin_lock_irqsave(&uprobes_treelock, flags);
uprobe = __find_uprobe(inode, offset);
spin_unlock_irqrestore(&uprobes_treelock, flags);
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) {
atomic_inc(&u->ref);
return 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;
}
/*
* Acquires 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)
{
unsigned long flags;
struct uprobe *u;
spin_lock_irqsave(&uprobes_treelock, flags);
u = __insert_uprobe(uprobe);
spin_unlock_irqrestore(&uprobes_treelock, flags);
return u;
}
static void put_uprobe(struct uprobe *uprobe)
{
if (atomic_dec_and_test(&uprobe->ref))
kfree(uprobe);
}
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->consumer_rwsem);
INIT_LIST_HEAD(&uprobe->pending_list);
/* 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);
} else
atomic_inc(&uprobe_events);
return uprobe;
}
/* Returns the previous consumer */
static struct uprobe_consumer *add_consumer(struct uprobe *uprobe,
struct uprobe_consumer *consumer)
{
down_write(&uprobe->consumer_rwsem);
consumer->next = uprobe->consumers;
uprobe->consumers = consumer;
up_write(&uprobe->consumer_rwsem);
return consumer->next;
}
/*
* For uprobe @uprobe, delete the consumer @consumer.
* Return true if the @consumer is deleted successfully
* or return false.
*/
static bool del_consumer(struct uprobe *uprobe,
struct uprobe_consumer *consumer)
{
struct uprobe_consumer **con;
bool ret = false;
down_write(&uprobe->consumer_rwsem);
for (con = &uprobe->consumers; *con; con = &(*con)->next) {
if (*con == consumer) {
*con = consumer->next;
ret = true;
break;
}
}
up_write(&uprobe->consumer_rwsem);
return ret;
}
static int __copy_insn(struct address_space *mapping,
struct vm_area_struct *vma, char *insn,
unsigned long nbytes, unsigned long offset)
{
struct file *filp = vma->vm_file;
struct page *page;
void *vaddr;
unsigned long off1;
unsigned long idx;
if (!filp)
return -EINVAL;
idx = (unsigned long)(offset >> PAGE_CACHE_SHIFT);
off1 = offset &= ~PAGE_MASK;
/*
* Ensure that the page that has the original instruction is
* populated and in page-cache.
*/
page = read_mapping_page(mapping, idx, filp);
if (IS_ERR(page))
return PTR_ERR(page);
vaddr = kmap_atomic(page);
memcpy(insn, vaddr + off1, nbytes);
kunmap_atomic(vaddr);
page_cache_release(page);
return 0;
}
static int copy_insn(struct uprobe *uprobe, struct vm_area_struct *vma,
unsigned long addr)
{
struct address_space *mapping;
int bytes;
unsigned long nbytes;
addr &= ~PAGE_MASK;
nbytes = PAGE_SIZE - addr;
mapping = uprobe->inode->i_mapping;
/* Instruction at end of binary; copy only available bytes */
if (uprobe->offset + MAX_UINSN_BYTES > uprobe->inode->i_size)
bytes = uprobe->inode->i_size - uprobe->offset;
else
bytes = MAX_UINSN_BYTES;
/* Instruction at the page-boundary; copy bytes in second page */
if (nbytes < bytes) {
if (__copy_insn(mapping, vma, uprobe->insn + nbytes,
bytes - nbytes, uprobe->offset + nbytes))
return -ENOMEM;
bytes = nbytes;
}
return __copy_insn(mapping, vma, uprobe->insn, bytes, uprobe->offset);
}
static int install_breakpoint(struct mm_struct *mm, struct uprobe *uprobe,
struct vm_area_struct *vma, loff_t vaddr)
{
unsigned long addr;
int ret;
/*
* If probe is being deleted, unregister thread could be done with
* the vma-rmap-walk through. Adding a probe now can be fatal since
* nobody will be able to cleanup. Also we could be from fork or
* mremap path, where the probe might have already been inserted.
* Hence behave as if probe already existed.
*/
if (!uprobe->consumers)
return -EEXIST;
addr = (unsigned long)vaddr;
if (!(uprobe->flags & UPROBES_COPY_INSN)) {
ret = copy_insn(uprobe, vma, addr);
if (ret)
return ret;
if (is_bkpt_insn((uprobe_opcode_t *)uprobe->insn))
return -EEXIST;
ret = analyze_insn(mm, uprobe);
if (ret)
return ret;
uprobe->flags |= UPROBES_COPY_INSN;
}
ret = set_bkpt(mm, uprobe, addr);
return ret;
}
static void remove_breakpoint(struct mm_struct *mm, struct uprobe *uprobe,
loff_t vaddr)
{
set_orig_insn(mm, uprobe, (unsigned long)vaddr, true);
}
static void delete_uprobe(struct uprobe *uprobe)
{
unsigned long flags;
spin_lock_irqsave(&uprobes_treelock, flags);
rb_erase(&uprobe->rb_node, &uprobes_tree);
spin_unlock_irqrestore(&uprobes_treelock, flags);
iput(uprobe->inode);
put_uprobe(uprobe);
atomic_dec(&uprobe_events);
}
static struct vma_info *__find_next_vma_info(struct list_head *head,
loff_t offset, struct address_space *mapping,
struct vma_info *vi, bool is_register)
{
struct prio_tree_iter iter;
struct vm_area_struct *vma;
struct vma_info *tmpvi;
loff_t vaddr;
unsigned long pgoff = offset >> PAGE_SHIFT;
int existing_vma;
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
if (!valid_vma(vma, is_register))
continue;
existing_vma = 0;
vaddr = vma_address(vma, offset);
list_for_each_entry(tmpvi, head, probe_list) {
if (tmpvi->mm == vma->vm_mm && tmpvi->vaddr == vaddr) {
existing_vma = 1;
break;
}
}
/*
* Another vma needs a probe to be installed. However skip
* installing the probe if the vma is about to be unlinked.
*/
if (!existing_vma &&
atomic_inc_not_zero(&vma->vm_mm->mm_users)) {
vi->mm = vma->vm_mm;
vi->vaddr = vaddr;
list_add(&vi->probe_list, head);
return vi;
}
}
return NULL;
}
/*
* Iterate in the rmap prio tree and find a vma where a probe has not
* yet been inserted.
*/
static struct vma_info *find_next_vma_info(struct list_head *head,
loff_t offset, struct address_space *mapping,
bool is_register)
{
struct vma_info *vi, *retvi;
vi = kzalloc(sizeof(struct vma_info), GFP_KERNEL);
if (!vi)
return ERR_PTR(-ENOMEM);
mutex_lock(&mapping->i_mmap_mutex);
retvi = __find_next_vma_info(head, offset, mapping, vi, is_register);
mutex_unlock(&mapping->i_mmap_mutex);
if (!retvi)
kfree(vi);
return retvi;
}
static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
{
struct list_head try_list;
struct vm_area_struct *vma;
struct address_space *mapping;
struct vma_info *vi, *tmpvi;
struct mm_struct *mm;
loff_t vaddr;
int ret = 0;
mapping = uprobe->inode->i_mapping;
INIT_LIST_HEAD(&try_list);
while ((vi = find_next_vma_info(&try_list, uprobe->offset,
mapping, is_register)) != NULL) {
if (IS_ERR(vi)) {
ret = PTR_ERR(vi);
break;
}
mm = vi->mm;
down_read(&mm->mmap_sem);
vma = find_vma(mm, (unsigned long)vi->vaddr);
if (!vma || !valid_vma(vma, is_register)) {
list_del(&vi->probe_list);
kfree(vi);
up_read(&mm->mmap_sem);
mmput(mm);
continue;
}
vaddr = vma_address(vma, uprobe->offset);
if (vma->vm_file->f_mapping->host != uprobe->inode ||
vaddr != vi->vaddr) {
list_del(&vi->probe_list);
kfree(vi);
up_read(&mm->mmap_sem);
mmput(mm);
continue;
}
if (is_register)
ret = install_breakpoint(mm, uprobe, vma, vi->vaddr);
else
remove_breakpoint(mm, uprobe, vi->vaddr);
up_read(&mm->mmap_sem);
mmput(mm);
if (is_register) {
if (ret && ret == -EEXIST)
ret = 0;
if (ret)
break;
}
}
list_for_each_entry_safe(vi, tmpvi, &try_list, probe_list) {
list_del(&vi->probe_list);
kfree(vi);
}
return ret;
}
static int __register_uprobe(struct uprobe *uprobe)
{
return register_for_each_vma(uprobe, true);
}
static void __unregister_uprobe(struct uprobe *uprobe)
{
if (!register_for_each_vma(uprobe, false))
delete_uprobe(uprobe);
/* TODO : cant unregister? schedule a worker thread */
}
/*
* register_uprobe - register a probe
* @inode: the file in which the probe has to be placed.
* @offset: offset from the start of the file.
* @consumer: information on howto handle the probe..
*
* Apart from the access refcount, register_uprobe() 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 unregister_uprobe from freeing the
* @uprobe even before the register operation is complete. Creation
* refcount is released when the last @consumer for the @uprobe
* unregisters.
*
* Return errno if it cannot successully install probes
* else return 0 (success)
*/
int register_uprobe(struct inode *inode, loff_t offset,
struct uprobe_consumer *consumer)
{
struct uprobe *uprobe;
int ret = -EINVAL;
if (!inode || !consumer || consumer->next)
return ret;
if (offset > i_size_read(inode))
return ret;
ret = 0;
mutex_lock(uprobes_hash(inode));
uprobe = alloc_uprobe(inode, offset);
if (uprobe && !add_consumer(uprobe, consumer)) {
ret = __register_uprobe(uprobe);
if (ret) {
uprobe->consumers = NULL;
__unregister_uprobe(uprobe);
} else
uprobe->flags |= UPROBES_RUN_HANDLER;
}
mutex_unlock(uprobes_hash(inode));
put_uprobe(uprobe);
return ret;
}
/*
* unregister_uprobe - unregister a already registered probe.
* @inode: the file in which the probe has to be removed.
* @offset: offset from the start of the file.
* @consumer: identify which probe if multiple probes are colocated.
*/
void unregister_uprobe(struct inode *inode, loff_t offset,
struct uprobe_consumer *consumer)
{
struct uprobe *uprobe = NULL;
if (!inode || !consumer)
return;
uprobe = find_uprobe(inode, offset);
if (!uprobe)
return;
mutex_lock(uprobes_hash(inode));
if (!del_consumer(uprobe, consumer))
goto unreg_out;
if (!uprobe->consumers) {
__unregister_uprobe(uprobe);
uprobe->flags &= ~UPROBES_RUN_HANDLER;
}
unreg_out:
mutex_unlock(uprobes_hash(inode));
if (uprobe)
put_uprobe(uprobe);
}
/*
* Of all the nodes that correspond to the given inode, return the node
* with the least offset.
*/
static struct rb_node *find_least_offset_node(struct inode *inode)
{
struct uprobe u = { .inode = inode, .offset = 0};
struct rb_node *n = uprobes_tree.rb_node;
struct rb_node *close_node = NULL;
struct uprobe *uprobe;
int match;
while (n) {
uprobe = rb_entry(n, struct uprobe, rb_node);
match = match_uprobe(&u, uprobe);
if (uprobe->inode == inode)
close_node = n;
if (!match)
return close_node;
if (match < 0)
n = n->rb_left;
else
n = n->rb_right;
}
return close_node;
}
/*
* For a given inode, build a list of probes that need to be inserted.
*/
static void build_probe_list(struct inode *inode, struct list_head *head)
{
struct uprobe *uprobe;
struct rb_node *n;
unsigned long flags;
spin_lock_irqsave(&uprobes_treelock, flags);
n = find_least_offset_node(inode);
for (; n; n = rb_next(n)) {
uprobe = rb_entry(n, struct uprobe, rb_node);
if (uprobe->inode != inode)
break;
list_add(&uprobe->pending_list, head);
atomic_inc(&uprobe->ref);
}
spin_unlock_irqrestore(&uprobes_treelock, flags);
}
/*
* Called from mmap_region.
* called with mm->mmap_sem acquired.
*
* Return -ve no if we fail to insert probes and we cannot
* bail-out.
* Return 0 otherwise. i.e :
* - successful insertion of probes
* - (or) no possible probes to be inserted.
* - (or) insertion of probes failed but we can bail-out.
*/
int mmap_uprobe(struct vm_area_struct *vma)
{
struct list_head tmp_list;
struct uprobe *uprobe, *u;
struct inode *inode;
int ret = 0;
if (!atomic_read(&uprobe_events) || !valid_vma(vma, true))
return ret; /* Bail-out */
inode = vma->vm_file->f_mapping->host;
if (!inode)
return ret;
INIT_LIST_HEAD(&tmp_list);
mutex_lock(uprobes_mmap_hash(inode));
build_probe_list(inode, &tmp_list);
list_for_each_entry_safe(uprobe, u, &tmp_list, pending_list) {
loff_t vaddr;
list_del(&uprobe->pending_list);
if (!ret) {
vaddr = vma_address(vma, uprobe->offset);
if (vaddr < vma->vm_start || vaddr >= vma->vm_end) {
put_uprobe(uprobe);
continue;
}
ret = install_breakpoint(vma->vm_mm, uprobe, vma,
vaddr);
if (ret == -EEXIST)
ret = 0;
}
put_uprobe(uprobe);
}
mutex_unlock(uprobes_mmap_hash(inode));
return ret;
}
static int __init init_uprobes(void)
{
int i;
for (i = 0; i < UPROBES_HASH_SZ; i++) {
mutex_init(&uprobes_mutex[i]);
mutex_init(&uprobes_mmap_mutex[i]);
}
return 0;
}
static void __exit exit_uprobes(void)
{
}
module_init(init_uprobes);
module_exit(exit_uprobes);
