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kprobes.c
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kprobes.c
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/*
* Kernel Probes (KProbes)
* kernel/kprobes.c
*
* 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, 2002, 2004
*
* 2002-Oct Created by Vamsi Krishna S <[email protected]> Kernel
* Probes initial implementation (includes suggestions from
* Rusty Russell).
* 2004-Aug Updated by Prasanna S Panchamukhi <[email protected]> with
* hlists and exceptions notifier as suggested by Andi Kleen.
* 2004-July Suparna Bhattacharya <[email protected]> added jumper probes
* interface to access function arguments.
* 2004-Sep Prasanna S Panchamukhi <[email protected]> Changed Kprobes
* exceptions notifier to be first on the priority list.
* 2005-May Hien Nguyen <[email protected]>, Jim Keniston
* <[email protected]> and Prasanna S Panchamukhi
* <[email protected]> added function-return probes.
*/
#include <linux/kprobes.h>
#include <linux/hash.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/stddef.h>
#include <linux/module.h>
#include <linux/moduleloader.h>
#include <linux/kallsyms.h>
#include <linux/freezer.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/kdebug.h>
#include <asm-generic/sections.h>
#include <asm/cacheflush.h>
#include <asm/errno.h>
#include <asm/uaccess.h>
#define KPROBE_HASH_BITS 6
#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
/*
* Some oddball architectures like 64bit powerpc have function descriptors
* so this must be overridable.
*/
#ifndef kprobe_lookup_name
#define kprobe_lookup_name(name, addr) \
addr = ((kprobe_opcode_t *)(kallsyms_lookup_name(name)))
#endif
static struct hlist_head kprobe_table[KPROBE_TABLE_SIZE];
static struct hlist_head kretprobe_inst_table[KPROBE_TABLE_SIZE];
/* NOTE: change this value only with kprobe_mutex held */
static bool kprobe_enabled;
DEFINE_MUTEX(kprobe_mutex); /* Protects kprobe_table */
DEFINE_SPINLOCK(kretprobe_lock); /* Protects kretprobe_inst_table */
static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
/*
* Normally, functions that we'd want to prohibit kprobes in, are marked
* __kprobes. But, there are cases where such functions already belong to
* a different section (__sched for preempt_schedule)
*
* For such cases, we now have a blacklist
*/
struct kprobe_blackpoint kprobe_blacklist[] = {
{"preempt_schedule",},
{NULL} /* Terminator */
};
#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
/*
* kprobe->ainsn.insn points to the copy of the instruction to be
* single-stepped. x86_64, POWER4 and above have no-exec support and
* stepping on the instruction on a vmalloced/kmalloced/data page
* is a recipe for disaster
*/
#define INSNS_PER_PAGE (PAGE_SIZE/(MAX_INSN_SIZE * sizeof(kprobe_opcode_t)))
struct kprobe_insn_page {
struct hlist_node hlist;
kprobe_opcode_t *insns; /* Page of instruction slots */
char slot_used[INSNS_PER_PAGE];
int nused;
int ngarbage;
};
enum kprobe_slot_state {
SLOT_CLEAN = 0,
SLOT_DIRTY = 1,
SLOT_USED = 2,
};
static struct hlist_head kprobe_insn_pages;
static int kprobe_garbage_slots;
static int collect_garbage_slots(void);
static int __kprobes check_safety(void)
{
int ret = 0;
#if defined(CONFIG_PREEMPT) && defined(CONFIG_PM)
ret = freeze_processes();
if (ret == 0) {
struct task_struct *p, *q;
do_each_thread(p, q) {
if (p != current && p->state == TASK_RUNNING &&
p->pid != 0) {
printk("Check failed: %s is running\n",p->comm);
ret = -1;
goto loop_end;
}
} while_each_thread(p, q);
}
loop_end:
thaw_processes();
#else
synchronize_sched();
#endif
return ret;
}
/**
* get_insn_slot() - Find a slot on an executable page for an instruction.
* We allocate an executable page if there's no room on existing ones.
*/
kprobe_opcode_t __kprobes *get_insn_slot(void)
{
struct kprobe_insn_page *kip;
struct hlist_node *pos;
retry:
hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
if (kip->nused < INSNS_PER_PAGE) {
int i;
for (i = 0; i < INSNS_PER_PAGE; i++) {
if (kip->slot_used[i] == SLOT_CLEAN) {
kip->slot_used[i] = SLOT_USED;
kip->nused++;
return kip->insns + (i * MAX_INSN_SIZE);
}
}
/* Surprise! No unused slots. Fix kip->nused. */
kip->nused = INSNS_PER_PAGE;
}
}
/* If there are any garbage slots, collect it and try again. */
if (kprobe_garbage_slots && collect_garbage_slots() == 0) {
goto retry;
}
/* All out of space. Need to allocate a new page. Use slot 0. */
kip = kmalloc(sizeof(struct kprobe_insn_page), GFP_KERNEL);
if (!kip)
return NULL;
/*
* Use module_alloc so this page is within +/- 2GB of where the
* kernel image and loaded module images reside. This is required
* so x86_64 can correctly handle the %rip-relative fixups.
*/
kip->insns = module_alloc(PAGE_SIZE);
if (!kip->insns) {
kfree(kip);
return NULL;
}
INIT_HLIST_NODE(&kip->hlist);
hlist_add_head(&kip->hlist, &kprobe_insn_pages);
memset(kip->slot_used, SLOT_CLEAN, INSNS_PER_PAGE);
kip->slot_used[0] = SLOT_USED;
kip->nused = 1;
kip->ngarbage = 0;
return kip->insns;
}
/* Return 1 if all garbages are collected, otherwise 0. */
static int __kprobes collect_one_slot(struct kprobe_insn_page *kip, int idx)
{
kip->slot_used[idx] = SLOT_CLEAN;
kip->nused--;
if (kip->nused == 0) {
/*
* Page is no longer in use. Free it unless
* it's the last one. We keep the last one
* so as not to have to set it up again the
* next time somebody inserts a probe.
*/
hlist_del(&kip->hlist);
if (hlist_empty(&kprobe_insn_pages)) {
INIT_HLIST_NODE(&kip->hlist);
hlist_add_head(&kip->hlist,
&kprobe_insn_pages);
} else {
module_free(NULL, kip->insns);
kfree(kip);
}
return 1;
}
return 0;
}
static int __kprobes collect_garbage_slots(void)
{
struct kprobe_insn_page *kip;
struct hlist_node *pos, *next;
/* Ensure no-one is preepmted on the garbages */
if (check_safety() != 0)
return -EAGAIN;
hlist_for_each_entry_safe(kip, pos, next, &kprobe_insn_pages, hlist) {
int i;
if (kip->ngarbage == 0)
continue;
kip->ngarbage = 0; /* we will collect all garbages */
for (i = 0; i < INSNS_PER_PAGE; i++) {
if (kip->slot_used[i] == SLOT_DIRTY &&
collect_one_slot(kip, i))
break;
}
}
kprobe_garbage_slots = 0;
return 0;
}
void __kprobes free_insn_slot(kprobe_opcode_t * slot, int dirty)
{
struct kprobe_insn_page *kip;
struct hlist_node *pos;
hlist_for_each_entry(kip, pos, &kprobe_insn_pages, hlist) {
if (kip->insns <= slot &&
slot < kip->insns + (INSNS_PER_PAGE * MAX_INSN_SIZE)) {
int i = (slot - kip->insns) / MAX_INSN_SIZE;
if (dirty) {
kip->slot_used[i] = SLOT_DIRTY;
kip->ngarbage++;
} else {
collect_one_slot(kip, i);
}
break;
}
}
if (dirty && ++kprobe_garbage_slots > INSNS_PER_PAGE)
collect_garbage_slots();
}
#endif
/* We have preemption disabled.. so it is safe to use __ versions */
static inline void set_kprobe_instance(struct kprobe *kp)
{
__get_cpu_var(kprobe_instance) = kp;
}
static inline void reset_kprobe_instance(void)
{
__get_cpu_var(kprobe_instance) = NULL;
}
/*
* This routine is called either:
* - under the kprobe_mutex - during kprobe_[un]register()
* OR
* - with preemption disabled - from arch/xxx/kernel/kprobes.c
*/
struct kprobe __kprobes *get_kprobe(void *addr)
{
struct hlist_head *head;
struct hlist_node *node;
struct kprobe *p;
head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
hlist_for_each_entry_rcu(p, node, head, hlist) {
if (p->addr == addr)
return p;
}
return NULL;
}
/*
* Aggregate handlers for multiple kprobes support - these handlers
* take care of invoking the individual kprobe handlers on p->list
*/
static int __kprobes aggr_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe *kp;
list_for_each_entry_rcu(kp, &p->list, list) {
if (kp->pre_handler) {
set_kprobe_instance(kp);
if (kp->pre_handler(kp, regs))
return 1;
}
reset_kprobe_instance();
}
return 0;
}
static void __kprobes aggr_post_handler(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
struct kprobe *kp;
list_for_each_entry_rcu(kp, &p->list, list) {
if (kp->post_handler) {
set_kprobe_instance(kp);
kp->post_handler(kp, regs, flags);
reset_kprobe_instance();
}
}
}
static int __kprobes aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
int trapnr)
{
struct kprobe *cur = __get_cpu_var(kprobe_instance);
/*
* if we faulted "during" the execution of a user specified
* probe handler, invoke just that probe's fault handler
*/
if (cur && cur->fault_handler) {
if (cur->fault_handler(cur, regs, trapnr))
return 1;
}
return 0;
}
static int __kprobes aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe *cur = __get_cpu_var(kprobe_instance);
int ret = 0;
if (cur && cur->break_handler) {
if (cur->break_handler(cur, regs))
ret = 1;
}
reset_kprobe_instance();
return ret;
}
/* Walks the list and increments nmissed count for multiprobe case */
void __kprobes kprobes_inc_nmissed_count(struct kprobe *p)
{
struct kprobe *kp;
if (p->pre_handler != aggr_pre_handler) {
p->nmissed++;
} else {
list_for_each_entry_rcu(kp, &p->list, list)
kp->nmissed++;
}
return;
}
/* Called with kretprobe_lock held */
void __kprobes recycle_rp_inst(struct kretprobe_instance *ri,
struct hlist_head *head)
{
/* remove rp inst off the rprobe_inst_table */
hlist_del(&ri->hlist);
if (ri->rp) {
/* remove rp inst off the used list */
hlist_del(&ri->uflist);
/* put rp inst back onto the free list */
INIT_HLIST_NODE(&ri->uflist);
hlist_add_head(&ri->uflist, &ri->rp->free_instances);
} else
/* Unregistering */
hlist_add_head(&ri->hlist, head);
}
struct hlist_head __kprobes *kretprobe_inst_table_head(struct task_struct *tsk)
{
return &kretprobe_inst_table[hash_ptr(tsk, KPROBE_HASH_BITS)];
}
/*
* This function is called from finish_task_switch when task tk becomes dead,
* so that we can recycle any function-return probe instances associated
* with this task. These left over instances represent probed functions
* that have been called but will never return.
*/
void __kprobes kprobe_flush_task(struct task_struct *tk)
{
struct kretprobe_instance *ri;
struct hlist_head *head, empty_rp;
struct hlist_node *node, *tmp;
unsigned long flags = 0;
INIT_HLIST_HEAD(&empty_rp);
spin_lock_irqsave(&kretprobe_lock, flags);
head = kretprobe_inst_table_head(tk);
hlist_for_each_entry_safe(ri, node, tmp, head, hlist) {
if (ri->task == tk)
recycle_rp_inst(ri, &empty_rp);
}
spin_unlock_irqrestore(&kretprobe_lock, flags);
hlist_for_each_entry_safe(ri, node, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
}
static inline void free_rp_inst(struct kretprobe *rp)
{
struct kretprobe_instance *ri;
struct hlist_node *pos, *next;
hlist_for_each_entry_safe(ri, pos, next, &rp->free_instances, uflist) {
hlist_del(&ri->uflist);
kfree(ri);
}
}
static void __kprobes cleanup_rp_inst(struct kretprobe *rp)
{
unsigned long flags;
struct kretprobe_instance *ri;
struct hlist_node *pos, *next;
/* No race here */
spin_lock_irqsave(&kretprobe_lock, flags);
hlist_for_each_entry_safe(ri, pos, next, &rp->used_instances, uflist) {
ri->rp = NULL;
hlist_del(&ri->uflist);
}
spin_unlock_irqrestore(&kretprobe_lock, flags);
free_rp_inst(rp);
}
/*
* Keep all fields in the kprobe consistent
*/
static inline void copy_kprobe(struct kprobe *old_p, struct kprobe *p)
{
memcpy(&p->opcode, &old_p->opcode, sizeof(kprobe_opcode_t));
memcpy(&p->ainsn, &old_p->ainsn, sizeof(struct arch_specific_insn));
}
/*
* Add the new probe to old_p->list. Fail if this is the
* second jprobe at the address - two jprobes can't coexist
*/
static int __kprobes add_new_kprobe(struct kprobe *old_p, struct kprobe *p)
{
if (p->break_handler) {
if (old_p->break_handler)
return -EEXIST;
list_add_tail_rcu(&p->list, &old_p->list);
old_p->break_handler = aggr_break_handler;
} else
list_add_rcu(&p->list, &old_p->list);
if (p->post_handler && !old_p->post_handler)
old_p->post_handler = aggr_post_handler;
return 0;
}
/*
* Fill in the required fields of the "manager kprobe". Replace the
* earlier kprobe in the hlist with the manager kprobe
*/
static inline void add_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
{
copy_kprobe(p, ap);
flush_insn_slot(ap);
ap->addr = p->addr;
ap->pre_handler = aggr_pre_handler;
ap->fault_handler = aggr_fault_handler;
if (p->post_handler)
ap->post_handler = aggr_post_handler;
if (p->break_handler)
ap->break_handler = aggr_break_handler;
INIT_LIST_HEAD(&ap->list);
list_add_rcu(&p->list, &ap->list);
hlist_replace_rcu(&p->hlist, &ap->hlist);
}
/*
* This is the second or subsequent kprobe at the address - handle
* the intricacies
*/
static int __kprobes register_aggr_kprobe(struct kprobe *old_p,
struct kprobe *p)
{
int ret = 0;
struct kprobe *ap;
if (old_p->pre_handler == aggr_pre_handler) {
copy_kprobe(old_p, p);
ret = add_new_kprobe(old_p, p);
} else {
ap = kzalloc(sizeof(struct kprobe), GFP_KERNEL);
if (!ap)
return -ENOMEM;
add_aggr_kprobe(ap, old_p);
copy_kprobe(ap, p);
ret = add_new_kprobe(ap, p);
}
return ret;
}
static int __kprobes in_kprobes_functions(unsigned long addr)
{
struct kprobe_blackpoint *kb;
if (addr >= (unsigned long)__kprobes_text_start &&
addr < (unsigned long)__kprobes_text_end)
return -EINVAL;
/*
* If there exists a kprobe_blacklist, verify and
* fail any probe registration in the prohibited area
*/
for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
if (kb->start_addr) {
if (addr >= kb->start_addr &&
addr < (kb->start_addr + kb->range))
return -EINVAL;
}
}
return 0;
}
/*
* If we have a symbol_name argument, look it up and add the offset field
* to it. This way, we can specify a relative address to a symbol.
*/
static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p)
{
kprobe_opcode_t *addr = p->addr;
if (p->symbol_name) {
if (addr)
return NULL;
kprobe_lookup_name(p->symbol_name, addr);
}
if (!addr)
return NULL;
return (kprobe_opcode_t *)(((char *)addr) + p->offset);
}
static int __kprobes __register_kprobe(struct kprobe *p,
unsigned long called_from)
{
int ret = 0;
struct kprobe *old_p;
struct module *probed_mod;
kprobe_opcode_t *addr;
addr = kprobe_addr(p);
if (!addr)
return -EINVAL;
p->addr = addr;
if (!kernel_text_address((unsigned long) p->addr) ||
in_kprobes_functions((unsigned long) p->addr))
return -EINVAL;
p->mod_refcounted = 0;
/*
* Check if are we probing a module.
*/
probed_mod = module_text_address((unsigned long) p->addr);
if (probed_mod) {
struct module *calling_mod = module_text_address(called_from);
/*
* We must allow modules to probe themself and in this case
* avoid incrementing the module refcount, so as to allow
* unloading of self probing modules.
*/
if (calling_mod && calling_mod != probed_mod) {
if (unlikely(!try_module_get(probed_mod)))
return -EINVAL;
p->mod_refcounted = 1;
} else
probed_mod = NULL;
}
p->nmissed = 0;
INIT_LIST_HEAD(&p->list);
mutex_lock(&kprobe_mutex);
old_p = get_kprobe(p->addr);
if (old_p) {
ret = register_aggr_kprobe(old_p, p);
goto out;
}
ret = arch_prepare_kprobe(p);
if (ret)
goto out;
INIT_HLIST_NODE(&p->hlist);
hlist_add_head_rcu(&p->hlist,
&kprobe_table[hash_ptr(p->addr, KPROBE_HASH_BITS)]);
if (kprobe_enabled)
arch_arm_kprobe(p);
out:
mutex_unlock(&kprobe_mutex);
if (ret && probed_mod)
module_put(probed_mod);
return ret;
}
/*
* Unregister a kprobe without a scheduler synchronization.
*/
static int __kprobes __unregister_kprobe_top(struct kprobe *p)
{
struct kprobe *old_p, *list_p;
old_p = get_kprobe(p->addr);
if (unlikely(!old_p))
return -EINVAL;
if (p != old_p) {
list_for_each_entry_rcu(list_p, &old_p->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid_p;
return -EINVAL;
}
valid_p:
if (old_p == p ||
(old_p->pre_handler == aggr_pre_handler &&
list_is_singular(&old_p->list))) {
/*
* Only probe on the hash list. Disarm only if kprobes are
* enabled - otherwise, the breakpoint would already have
* been removed. We save on flushing icache.
*/
if (kprobe_enabled)
arch_disarm_kprobe(p);
hlist_del_rcu(&old_p->hlist);
} else {
if (p->break_handler)
old_p->break_handler = NULL;
if (p->post_handler) {
list_for_each_entry_rcu(list_p, &old_p->list, list) {
if ((list_p != p) && (list_p->post_handler))
goto noclean;
}
old_p->post_handler = NULL;
}
noclean:
list_del_rcu(&p->list);
}
return 0;
}
static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
{
struct module *mod;
struct kprobe *old_p;
if (p->mod_refcounted) {
mod = module_text_address((unsigned long)p->addr);
if (mod)
module_put(mod);
}
if (list_empty(&p->list) || list_is_singular(&p->list)) {
if (!list_empty(&p->list)) {
/* "p" is the last child of an aggr_kprobe */
old_p = list_entry(p->list.next, struct kprobe, list);
list_del(&p->list);
kfree(old_p);
}
arch_remove_kprobe(p);
}
}
static int __register_kprobes(struct kprobe **kps, int num,
unsigned long called_from)
{
int i, ret = 0;
if (num <= 0)
return -EINVAL;
for (i = 0; i < num; i++) {
ret = __register_kprobe(kps[i], called_from);
if (ret < 0) {
if (i > 0)
unregister_kprobes(kps, i);
break;
}
}
return ret;
}
/*
* Registration and unregistration functions for kprobe.
*/
int __kprobes register_kprobe(struct kprobe *p)
{
return __register_kprobes(&p, 1,
(unsigned long)__builtin_return_address(0));
}
void __kprobes unregister_kprobe(struct kprobe *p)
{
unregister_kprobes(&p, 1);
}
int __kprobes register_kprobes(struct kprobe **kps, int num)
{
return __register_kprobes(kps, num,
(unsigned long)__builtin_return_address(0));
}
void __kprobes unregister_kprobes(struct kprobe **kps, int num)
{
int i;
if (num <= 0)
return;
mutex_lock(&kprobe_mutex);
for (i = 0; i < num; i++)
if (__unregister_kprobe_top(kps[i]) < 0)
kps[i]->addr = NULL;
mutex_unlock(&kprobe_mutex);
synchronize_sched();
for (i = 0; i < num; i++)
if (kps[i]->addr)
__unregister_kprobe_bottom(kps[i]);
}
static struct notifier_block kprobe_exceptions_nb = {
.notifier_call = kprobe_exceptions_notify,
.priority = 0x7fffffff /* we need to be notified first */
};
unsigned long __weak arch_deref_entry_point(void *entry)
{
return (unsigned long)entry;
}
static int __register_jprobes(struct jprobe **jps, int num,
unsigned long called_from)
{
struct jprobe *jp;
int ret = 0, i;
if (num <= 0)
return -EINVAL;
for (i = 0; i < num; i++) {
unsigned long addr;
jp = jps[i];
addr = arch_deref_entry_point(jp->entry);
if (!kernel_text_address(addr))
ret = -EINVAL;
else {
/* Todo: Verify probepoint is a function entry point */
jp->kp.pre_handler = setjmp_pre_handler;
jp->kp.break_handler = longjmp_break_handler;
ret = __register_kprobe(&jp->kp, called_from);
}
if (ret < 0) {
if (i > 0)
unregister_jprobes(jps, i);
break;
}
}
return ret;
}
int __kprobes register_jprobe(struct jprobe *jp)
{
return __register_jprobes(&jp, 1,
(unsigned long)__builtin_return_address(0));
}
void __kprobes unregister_jprobe(struct jprobe *jp)
{
unregister_jprobes(&jp, 1);
}
int __kprobes register_jprobes(struct jprobe **jps, int num)
{
return __register_jprobes(jps, num,
(unsigned long)__builtin_return_address(0));
}
void __kprobes unregister_jprobes(struct jprobe **jps, int num)
{
int i;
if (num <= 0)
return;
mutex_lock(&kprobe_mutex);
for (i = 0; i < num; i++)
if (__unregister_kprobe_top(&jps[i]->kp) < 0)
jps[i]->kp.addr = NULL;
mutex_unlock(&kprobe_mutex);
synchronize_sched();
for (i = 0; i < num; i++) {
if (jps[i]->kp.addr)
__unregister_kprobe_bottom(&jps[i]->kp);
}
}
#ifdef CONFIG_KRETPROBES
/*
* This kprobe pre_handler is registered with every kretprobe. When probe
* hits it will set up the return probe.
*/
static int __kprobes pre_handler_kretprobe(struct kprobe *p,
struct pt_regs *regs)
{
struct kretprobe *rp = container_of(p, struct kretprobe, kp);
unsigned long flags = 0;
/*TODO: consider to only swap the RA after the last pre_handler fired */
spin_lock_irqsave(&kretprobe_lock, flags);
if (!hlist_empty(&rp->free_instances)) {
struct kretprobe_instance *ri;
ri = hlist_entry(rp->free_instances.first,
struct kretprobe_instance, uflist);
ri->rp = rp;
ri->task = current;
if (rp->entry_handler && rp->entry_handler(ri, regs)) {
spin_unlock_irqrestore(&kretprobe_lock, flags);
return 0;
}
arch_prepare_kretprobe(ri, regs);
/* XXX(hch): why is there no hlist_move_head? */
hlist_del(&ri->uflist);
hlist_add_head(&ri->uflist, &ri->rp->used_instances);
hlist_add_head(&ri->hlist, kretprobe_inst_table_head(ri->task));
} else
rp->nmissed++;
spin_unlock_irqrestore(&kretprobe_lock, flags);
return 0;
}
static int __kprobes __register_kretprobe(struct kretprobe *rp,
unsigned long called_from)
{
int ret = 0;
struct kretprobe_instance *inst;
int i;
void *addr;
if (kretprobe_blacklist_size) {
addr = kprobe_addr(&rp->kp);
if (!addr)
return -EINVAL;
for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
if (kretprobe_blacklist[i].addr == addr)
return -EINVAL;
}
}
rp->kp.pre_handler = pre_handler_kretprobe;
rp->kp.post_handler = NULL;
rp->kp.fault_handler = NULL;
rp->kp.break_handler = NULL;
/* Pre-allocate memory for max kretprobe instances */
if (rp->maxactive <= 0) {
#ifdef CONFIG_PREEMPT
rp->maxactive = max(10, 2 * NR_CPUS);
#else
rp->maxactive = NR_CPUS;
#endif
}
INIT_HLIST_HEAD(&rp->used_instances);
INIT_HLIST_HEAD(&rp->free_instances);
for (i = 0; i < rp->maxactive; i++) {
inst = kmalloc(sizeof(struct kretprobe_instance) +
rp->data_size, GFP_KERNEL);
if (inst == NULL) {
free_rp_inst(rp);
return -ENOMEM;
}
INIT_HLIST_NODE(&inst->uflist);
hlist_add_head(&inst->uflist, &rp->free_instances);
}
rp->nmissed = 0;
/* Establish function entry probe point */
ret = __register_kprobe(&rp->kp, called_from);
if (ret != 0)
free_rp_inst(rp);
return ret;
}
static int __register_kretprobes(struct kretprobe **rps, int num,
unsigned long called_from)
{
int ret = 0, i;
if (num <= 0)
return -EINVAL;
for (i = 0; i < num; i++) {
ret = __register_kretprobe(rps[i], called_from);
if (ret < 0) {
if (i > 0)
unregister_kretprobes(rps, i);
break;
}
}
return ret;
}
int __kprobes register_kretprobe(struct kretprobe *rp)
{
return __register_kretprobes(&rp, 1,
(unsigned long)__builtin_return_address(0));
}
void __kprobes unregister_kretprobe(struct kretprobe *rp)
{
unregister_kretprobes(&rp, 1);
}
int __kprobes register_kretprobes(struct kretprobe **rps, int num)
{
return __register_kretprobes(rps, num,
(unsigned long)__builtin_return_address(0));
}
void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
{
int i;
if (num <= 0)
return;
mutex_lock(&kprobe_mutex);
for (i = 0; i < num; i++)
if (__unregister_kprobe_top(&rps[i]->kp) < 0)
rps[i]->kp.addr = NULL;
mutex_unlock(&kprobe_mutex);
synchronize_sched();
for (i = 0; i < num; i++) {
if (rps[i]->kp.addr) {
__unregister_kprobe_bottom(&rps[i]->kp);
cleanup_rp_inst(rps[i]);
}
}
}
#else /* CONFIG_KRETPROBES */
int __kprobes register_kretprobe(struct kretprobe *rp)
{
return -ENOSYS;
}
int __kprobes register_kretprobes(struct kretprobe **rps, int num)
{
return -ENOSYS;
}
void __kprobes unregister_kretprobe(struct kretprobe *rp)
{
}
void __kprobes unregister_kretprobes(struct kretprobe **rps, int num)
{
}
static int __kprobes pre_handler_kretprobe(struct kprobe *p,
struct pt_regs *regs)
{
return 0;
}
#endif /* CONFIG_KRETPROBES */
static int __init init_kprobes(void)
{
int i, err = 0;