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linux/kernel/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 <vamsi_krishna@in.ibm.com> Kernel
* Probes initial implementation (includes suggestions from
* Rusty Russell).
* 2004-Aug Updated by Prasanna S Panchamukhi <prasanna@in.ibm.com> with
* hlists and exceptions notifier as suggested by Andi Kleen.
* 2004-July Suparna Bhattacharya <suparna@in.ibm.com> added jumper probes
* interface to access function arguments.
* 2004-Sep Prasanna S Panchamukhi <prasanna@in.ibm.com> Changed Kprobes
* exceptions notifier to be first on the priority list.
* 2005-May Hien Nguyen <hien@us.ibm.com>, Jim Keniston
* <jkenisto@us.ibm.com> and Prasanna S Panchamukhi
* <prasanna@in.ibm.com> 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/export.h>
#include <linux/moduleloader.h>
#include <linux/kallsyms.h>
#include <linux/freezer.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/sysctl.h>
#include <linux/kdebug.h>
#include <linux/memory.h>
#include <linux/ftrace.h>
#include <linux/cpu.h>
#include <linux/jump_label.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 int kprobes_initialized;
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 kprobes_all_disarmed;
/* This protects kprobe_table and optimizing_list */
static DEFINE_MUTEX(kprobe_mutex);
static DEFINE_PER_CPU(struct kprobe *, kprobe_instance) = NULL;
static struct {
raw_spinlock_t lock ____cacheline_aligned_in_smp;
} kretprobe_table_locks[KPROBE_TABLE_SIZE];
static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
{
return &(kretprobe_table_locks[hash].lock);
}
/* Blacklist -- list of struct kprobe_blacklist_entry */
static LIST_HEAD(kprobe_blacklist);
#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
*/
struct kprobe_insn_page {
struct list_head list;
kprobe_opcode_t *insns; /* Page of instruction slots */
struct kprobe_insn_cache *cache;
int nused;
int ngarbage;
char slot_used[];
};
#define KPROBE_INSN_PAGE_SIZE(slots) \
(offsetof(struct kprobe_insn_page, slot_used) + \
(sizeof(char) * (slots)))
static int slots_per_page(struct kprobe_insn_cache *c)
{
return PAGE_SIZE/(c->insn_size * sizeof(kprobe_opcode_t));
}
enum kprobe_slot_state {
SLOT_CLEAN = 0,
SLOT_DIRTY = 1,
SLOT_USED = 2,
};
static void *alloc_insn_page(void)
{
return module_alloc(PAGE_SIZE);
}
static void free_insn_page(void *page)
{
module_free(NULL, page);
}
struct kprobe_insn_cache kprobe_insn_slots = {
.mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
.alloc = alloc_insn_page,
.free = free_insn_page,
.pages = LIST_HEAD_INIT(kprobe_insn_slots.pages),
.insn_size = MAX_INSN_SIZE,
.nr_garbage = 0,
};
static int collect_garbage_slots(struct kprobe_insn_cache *c);
/**
* __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 *__get_insn_slot(struct kprobe_insn_cache *c)
{
struct kprobe_insn_page *kip;
kprobe_opcode_t *slot = NULL;
mutex_lock(&c->mutex);
retry:
list_for_each_entry(kip, &c->pages, list) {
if (kip->nused < slots_per_page(c)) {
int i;
for (i = 0; i < slots_per_page(c); i++) {
if (kip->slot_used[i] == SLOT_CLEAN) {
kip->slot_used[i] = SLOT_USED;
kip->nused++;
slot = kip->insns + (i * c->insn_size);
goto out;
}
}
/* kip->nused is broken. Fix it. */
kip->nused = slots_per_page(c);
WARN_ON(1);
}
}
/* If there are any garbage slots, collect it and try again. */
if (c->nr_garbage && collect_garbage_slots(c) == 0)
goto retry;
/* All out of space. Need to allocate a new page. */
kip = kmalloc(KPROBE_INSN_PAGE_SIZE(slots_per_page(c)), GFP_KERNEL);
if (!kip)
goto out;
/*
* 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 = c->alloc();
if (!kip->insns) {
kfree(kip);
goto out;
}
INIT_LIST_HEAD(&kip->list);
memset(kip->slot_used, SLOT_CLEAN, slots_per_page(c));
kip->slot_used[0] = SLOT_USED;
kip->nused = 1;
kip->ngarbage = 0;
kip->cache = c;
list_add(&kip->list, &c->pages);
slot = kip->insns;
out:
mutex_unlock(&c->mutex);
return slot;
}
/* Return 1 if all garbages are collected, otherwise 0. */
static int 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.
*/
if (!list_is_singular(&kip->list)) {
list_del(&kip->list);
kip->cache->free(kip->insns);
kfree(kip);
}
return 1;
}
return 0;
}
static int collect_garbage_slots(struct kprobe_insn_cache *c)
{
struct kprobe_insn_page *kip, *next;
/* Ensure no-one is interrupted on the garbages */
synchronize_sched();
list_for_each_entry_safe(kip, next, &c->pages, list) {
int i;
if (kip->ngarbage == 0)
continue;
kip->ngarbage = 0; /* we will collect all garbages */
for (i = 0; i < slots_per_page(c); i++) {
if (kip->slot_used[i] == SLOT_DIRTY &&
collect_one_slot(kip, i))
break;
}
}
c->nr_garbage = 0;
return 0;
}
void __free_insn_slot(struct kprobe_insn_cache *c,
kprobe_opcode_t *slot, int dirty)
{
struct kprobe_insn_page *kip;
mutex_lock(&c->mutex);
list_for_each_entry(kip, &c->pages, list) {
long idx = ((long)slot - (long)kip->insns) /
(c->insn_size * sizeof(kprobe_opcode_t));
if (idx >= 0 && idx < slots_per_page(c)) {
WARN_ON(kip->slot_used[idx] != SLOT_USED);
if (dirty) {
kip->slot_used[idx] = SLOT_DIRTY;
kip->ngarbage++;
if (++c->nr_garbage > slots_per_page(c))
collect_garbage_slots(c);
} else
collect_one_slot(kip, idx);
goto out;
}
}
/* Could not free this slot. */
WARN_ON(1);
out:
mutex_unlock(&c->mutex);
}
#ifdef CONFIG_OPTPROBES
/* For optimized_kprobe buffer */
struct kprobe_insn_cache kprobe_optinsn_slots = {
.mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
.alloc = alloc_insn_page,
.free = free_insn_page,
.pages = LIST_HEAD_INIT(kprobe_optinsn_slots.pages),
/* .insn_size is initialized later */
.nr_garbage = 0,
};
#endif
#endif
/* We have preemption disabled.. so it is safe to use __ versions */
static inline void set_kprobe_instance(struct kprobe *kp)
{
__this_cpu_write(kprobe_instance, kp);
}
static inline void reset_kprobe_instance(void)
{
__this_cpu_write(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 *get_kprobe(void *addr)
{
struct hlist_head *head;
struct kprobe *p;
head = &kprobe_table[hash_ptr(addr, KPROBE_HASH_BITS)];
hlist_for_each_entry_rcu(p, head, hlist) {
if (p->addr == addr)
return p;
}
return NULL;
}
NOKPROBE_SYMBOL(get_kprobe);
static int aggr_pre_handler(struct kprobe *p, struct pt_regs *regs);
/* Return true if the kprobe is an aggregator */
static inline int kprobe_aggrprobe(struct kprobe *p)
{
return p->pre_handler == aggr_pre_handler;
}
/* Return true(!0) if the kprobe is unused */
static inline int kprobe_unused(struct kprobe *p)
{
return kprobe_aggrprobe(p) && kprobe_disabled(p) &&
list_empty(&p->list);
}
/*
* Keep all fields in the kprobe consistent
*/
static inline void copy_kprobe(struct kprobe *ap, struct kprobe *p)
{
memcpy(&p->opcode, &ap->opcode, sizeof(kprobe_opcode_t));
memcpy(&p->ainsn, &ap->ainsn, sizeof(struct arch_specific_insn));
}
#ifdef CONFIG_OPTPROBES
/* NOTE: change this value only with kprobe_mutex held */
static bool kprobes_allow_optimization;
/*
* Call all pre_handler on the list, but ignores its return value.
* This must be called from arch-dep optimized caller.
*/
void opt_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 && likely(!kprobe_disabled(kp))) {
set_kprobe_instance(kp);
kp->pre_handler(kp, regs);
}
reset_kprobe_instance();
}
}
NOKPROBE_SYMBOL(opt_pre_handler);
/* Free optimized instructions and optimized_kprobe */
static void free_aggr_kprobe(struct kprobe *p)
{
struct optimized_kprobe *op;
op = container_of(p, struct optimized_kprobe, kp);
arch_remove_optimized_kprobe(op);
arch_remove_kprobe(p);
kfree(op);
}
/* Return true(!0) if the kprobe is ready for optimization. */
static inline int kprobe_optready(struct kprobe *p)
{
struct optimized_kprobe *op;
if (kprobe_aggrprobe(p)) {
op = container_of(p, struct optimized_kprobe, kp);
return arch_prepared_optinsn(&op->optinsn);
}
return 0;
}
/* Return true(!0) if the kprobe is disarmed. Note: p must be on hash list */
static inline int kprobe_disarmed(struct kprobe *p)
{
struct optimized_kprobe *op;
/* If kprobe is not aggr/opt probe, just return kprobe is disabled */
if (!kprobe_aggrprobe(p))
return kprobe_disabled(p);
op = container_of(p, struct optimized_kprobe, kp);
return kprobe_disabled(p) && list_empty(&op->list);
}
/* Return true(!0) if the probe is queued on (un)optimizing lists */
static int kprobe_queued(struct kprobe *p)
{
struct optimized_kprobe *op;
if (kprobe_aggrprobe(p)) {
op = container_of(p, struct optimized_kprobe, kp);
if (!list_empty(&op->list))
return 1;
}
return 0;
}
/*
* Return an optimized kprobe whose optimizing code replaces
* instructions including addr (exclude breakpoint).
*/
static struct kprobe *get_optimized_kprobe(unsigned long addr)
{
int i;
struct kprobe *p = NULL;
struct optimized_kprobe *op;
/* Don't check i == 0, since that is a breakpoint case. */
for (i = 1; !p && i < MAX_OPTIMIZED_LENGTH; i++)
p = get_kprobe((void *)(addr - i));
if (p && kprobe_optready(p)) {
op = container_of(p, struct optimized_kprobe, kp);
if (arch_within_optimized_kprobe(op, addr))
return p;
}
return NULL;
}
/* Optimization staging list, protected by kprobe_mutex */
static LIST_HEAD(optimizing_list);
static LIST_HEAD(unoptimizing_list);
static LIST_HEAD(freeing_list);
static void kprobe_optimizer(struct work_struct *work);
static DECLARE_DELAYED_WORK(optimizing_work, kprobe_optimizer);
#define OPTIMIZE_DELAY 5
/*
* Optimize (replace a breakpoint with a jump) kprobes listed on
* optimizing_list.
*/
static void do_optimize_kprobes(void)
{
/* Optimization never be done when disarmed */
if (kprobes_all_disarmed || !kprobes_allow_optimization ||
list_empty(&optimizing_list))
return;
/*
* The optimization/unoptimization refers online_cpus via
* stop_machine() and cpu-hotplug modifies online_cpus.
* And same time, text_mutex will be held in cpu-hotplug and here.
* This combination can cause a deadlock (cpu-hotplug try to lock
* text_mutex but stop_machine can not be done because online_cpus
* has been changed)
* To avoid this deadlock, we need to call get_online_cpus()
* for preventing cpu-hotplug outside of text_mutex locking.
*/
get_online_cpus();
mutex_lock(&text_mutex);
arch_optimize_kprobes(&optimizing_list);
mutex_unlock(&text_mutex);
put_online_cpus();
}
/*
* Unoptimize (replace a jump with a breakpoint and remove the breakpoint
* if need) kprobes listed on unoptimizing_list.
*/
static void do_unoptimize_kprobes(void)
{
struct optimized_kprobe *op, *tmp;
/* Unoptimization must be done anytime */
if (list_empty(&unoptimizing_list))
return;
/* Ditto to do_optimize_kprobes */
get_online_cpus();
mutex_lock(&text_mutex);
arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
/* Loop free_list for disarming */
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
/* Disarm probes if marked disabled */
if (kprobe_disabled(&op->kp))
arch_disarm_kprobe(&op->kp);
if (kprobe_unused(&op->kp)) {
/*
* Remove unused probes from hash list. After waiting
* for synchronization, these probes are reclaimed.
* (reclaiming is done by do_free_cleaned_kprobes.)
*/
hlist_del_rcu(&op->kp.hlist);
} else
list_del_init(&op->list);
}
mutex_unlock(&text_mutex);
put_online_cpus();
}
/* Reclaim all kprobes on the free_list */
static void do_free_cleaned_kprobes(void)
{
struct optimized_kprobe *op, *tmp;
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
BUG_ON(!kprobe_unused(&op->kp));
list_del_init(&op->list);
free_aggr_kprobe(&op->kp);
}
}
/* Start optimizer after OPTIMIZE_DELAY passed */
static void kick_kprobe_optimizer(void)
{
schedule_delayed_work(&optimizing_work, OPTIMIZE_DELAY);
}
/* Kprobe jump optimizer */
static void kprobe_optimizer(struct work_struct *work)
{
mutex_lock(&kprobe_mutex);
/* Lock modules while optimizing kprobes */
mutex_lock(&module_mutex);
/*
* Step 1: Unoptimize kprobes and collect cleaned (unused and disarmed)
* kprobes before waiting for quiesence period.
*/
do_unoptimize_kprobes();
/*
* Step 2: Wait for quiesence period to ensure all running interrupts
* are done. Because optprobe may modify multiple instructions
* there is a chance that Nth instruction is interrupted. In that
* case, running interrupt can return to 2nd-Nth byte of jump
* instruction. This wait is for avoiding it.
*/
synchronize_sched();
/* Step 3: Optimize kprobes after quiesence period */
do_optimize_kprobes();
/* Step 4: Free cleaned kprobes after quiesence period */
do_free_cleaned_kprobes();
mutex_unlock(&module_mutex);
mutex_unlock(&kprobe_mutex);
/* Step 5: Kick optimizer again if needed */
if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
kick_kprobe_optimizer();
}
/* Wait for completing optimization and unoptimization */
static void wait_for_kprobe_optimizer(void)
{
mutex_lock(&kprobe_mutex);
while (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list)) {
mutex_unlock(&kprobe_mutex);
/* this will also make optimizing_work execute immmediately */
flush_delayed_work(&optimizing_work);
/* @optimizing_work might not have been queued yet, relax */
cpu_relax();
mutex_lock(&kprobe_mutex);
}
mutex_unlock(&kprobe_mutex);
}
/* Optimize kprobe if p is ready to be optimized */
static void optimize_kprobe(struct kprobe *p)
{
struct optimized_kprobe *op;
/* Check if the kprobe is disabled or not ready for optimization. */
if (!kprobe_optready(p) || !kprobes_allow_optimization ||
(kprobe_disabled(p) || kprobes_all_disarmed))
return;
/* Both of break_handler and post_handler are not supported. */
if (p->break_handler || p->post_handler)
return;
op = container_of(p, struct optimized_kprobe, kp);
/* Check there is no other kprobes at the optimized instructions */
if (arch_check_optimized_kprobe(op) < 0)
return;
/* Check if it is already optimized. */
if (op->kp.flags & KPROBE_FLAG_OPTIMIZED)
return;
op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
if (!list_empty(&op->list))
/* This is under unoptimizing. Just dequeue the probe */
list_del_init(&op->list);
else {
list_add(&op->list, &optimizing_list);
kick_kprobe_optimizer();
}
}
/* Short cut to direct unoptimizing */
static void force_unoptimize_kprobe(struct optimized_kprobe *op)
{
get_online_cpus();
arch_unoptimize_kprobe(op);
put_online_cpus();
if (kprobe_disabled(&op->kp))
arch_disarm_kprobe(&op->kp);
}
/* Unoptimize a kprobe if p is optimized */
static void unoptimize_kprobe(struct kprobe *p, bool force)
{
struct optimized_kprobe *op;
if (!kprobe_aggrprobe(p) || kprobe_disarmed(p))
return; /* This is not an optprobe nor optimized */
op = container_of(p, struct optimized_kprobe, kp);
if (!kprobe_optimized(p)) {
/* Unoptimized or unoptimizing case */
if (force && !list_empty(&op->list)) {
/*
* Only if this is unoptimizing kprobe and forced,
* forcibly unoptimize it. (No need to unoptimize
* unoptimized kprobe again :)
*/
list_del_init(&op->list);
force_unoptimize_kprobe(op);
}
return;
}
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
if (!list_empty(&op->list)) {
/* Dequeue from the optimization queue */
list_del_init(&op->list);
return;
}
/* Optimized kprobe case */
if (force)
/* Forcibly update the code: this is a special case */
force_unoptimize_kprobe(op);
else {
list_add(&op->list, &unoptimizing_list);
kick_kprobe_optimizer();
}
}
/* Cancel unoptimizing for reusing */
static void reuse_unused_kprobe(struct kprobe *ap)
{
struct optimized_kprobe *op;
BUG_ON(!kprobe_unused(ap));
/*
* Unused kprobe MUST be on the way of delayed unoptimizing (means
* there is still a relative jump) and disabled.
*/
op = container_of(ap, struct optimized_kprobe, kp);
if (unlikely(list_empty(&op->list)))
printk(KERN_WARNING "Warning: found a stray unused "
"aggrprobe@%p\n", ap->addr);
/* Enable the probe again */
ap->flags &= ~KPROBE_FLAG_DISABLED;
/* Optimize it again (remove from op->list) */
BUG_ON(!kprobe_optready(ap));
optimize_kprobe(ap);
}
/* Remove optimized instructions */
static void kill_optimized_kprobe(struct kprobe *p)
{
struct optimized_kprobe *op;
op = container_of(p, struct optimized_kprobe, kp);
if (!list_empty(&op->list))
/* Dequeue from the (un)optimization queue */
list_del_init(&op->list);
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
if (kprobe_unused(p)) {
/* Enqueue if it is unused */
list_add(&op->list, &freeing_list);
/*
* Remove unused probes from the hash list. After waiting
* for synchronization, this probe is reclaimed.
* (reclaiming is done by do_free_cleaned_kprobes().)
*/
hlist_del_rcu(&op->kp.hlist);
}
/* Don't touch the code, because it is already freed. */
arch_remove_optimized_kprobe(op);
}
/* Try to prepare optimized instructions */
static void prepare_optimized_kprobe(struct kprobe *p)
{
struct optimized_kprobe *op;
op = container_of(p, struct optimized_kprobe, kp);
arch_prepare_optimized_kprobe(op);
}
/* Allocate new optimized_kprobe and try to prepare optimized instructions */
static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
{
struct optimized_kprobe *op;
op = kzalloc(sizeof(struct optimized_kprobe), GFP_KERNEL);
if (!op)
return NULL;
INIT_LIST_HEAD(&op->list);
op->kp.addr = p->addr;
arch_prepare_optimized_kprobe(op);
return &op->kp;
}
static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p);
/*
* Prepare an optimized_kprobe and optimize it
* NOTE: p must be a normal registered kprobe
*/
static void try_to_optimize_kprobe(struct kprobe *p)
{
struct kprobe *ap;
struct optimized_kprobe *op;
/* Impossible to optimize ftrace-based kprobe */
if (kprobe_ftrace(p))
return;
/* For preparing optimization, jump_label_text_reserved() is called */
jump_label_lock();
mutex_lock(&text_mutex);
ap = alloc_aggr_kprobe(p);
if (!ap)
goto out;
op = container_of(ap, struct optimized_kprobe, kp);
if (!arch_prepared_optinsn(&op->optinsn)) {
/* If failed to setup optimizing, fallback to kprobe */
arch_remove_optimized_kprobe(op);
kfree(op);
goto out;
}
init_aggr_kprobe(ap, p);
optimize_kprobe(ap); /* This just kicks optimizer thread */
out:
mutex_unlock(&text_mutex);
jump_label_unlock();
}
#ifdef CONFIG_SYSCTL
static void optimize_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
mutex_lock(&kprobe_mutex);
/* If optimization is already allowed, just return */
if (kprobes_allow_optimization)
goto out;
kprobes_allow_optimization = true;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry_rcu(p, head, hlist)
if (!kprobe_disabled(p))
optimize_kprobe(p);
}
printk(KERN_INFO "Kprobes globally optimized\n");
out:
mutex_unlock(&kprobe_mutex);
}
static void unoptimize_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
mutex_lock(&kprobe_mutex);
/* If optimization is already prohibited, just return */
if (!kprobes_allow_optimization) {
mutex_unlock(&kprobe_mutex);
return;
}
kprobes_allow_optimization = false;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry_rcu(p, head, hlist) {
if (!kprobe_disabled(p))
unoptimize_kprobe(p, false);
}
}
mutex_unlock(&kprobe_mutex);
/* Wait for unoptimizing completion */
wait_for_kprobe_optimizer();
printk(KERN_INFO "Kprobes globally unoptimized\n");
}
static DEFINE_MUTEX(kprobe_sysctl_mutex);
int sysctl_kprobes_optimization;
int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *length,
loff_t *ppos)
{
int ret;
mutex_lock(&kprobe_sysctl_mutex);
sysctl_kprobes_optimization = kprobes_allow_optimization ? 1 : 0;
ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (sysctl_kprobes_optimization)
optimize_all_kprobes();
else
unoptimize_all_kprobes();
mutex_unlock(&kprobe_sysctl_mutex);
return ret;
}
#endif /* CONFIG_SYSCTL */
/* Put a breakpoint for a probe. Must be called with text_mutex locked */
static void __arm_kprobe(struct kprobe *p)
{
struct kprobe *_p;
/* Check collision with other optimized kprobes */
_p = get_optimized_kprobe((unsigned long)p->addr);
if (unlikely(_p))
/* Fallback to unoptimized kprobe */
unoptimize_kprobe(_p, true);
arch_arm_kprobe(p);
optimize_kprobe(p); /* Try to optimize (add kprobe to a list) */
}
/* Remove the breakpoint of a probe. Must be called with text_mutex locked */
static void __disarm_kprobe(struct kprobe *p, bool reopt)
{
struct kprobe *_p;
unoptimize_kprobe(p, false); /* Try to unoptimize */
if (!kprobe_queued(p)) {
arch_disarm_kprobe(p);
/* If another kprobe was blocked, optimize it. */
_p = get_optimized_kprobe((unsigned long)p->addr);
if (unlikely(_p) && reopt)
optimize_kprobe(_p);
}
/* TODO: reoptimize others after unoptimized this probe */
}
#else /* !CONFIG_OPTPROBES */
#define optimize_kprobe(p) do {} while (0)
#define unoptimize_kprobe(p, f) do {} while (0)
#define kill_optimized_kprobe(p) do {} while (0)
#define prepare_optimized_kprobe(p) do {} while (0)
#define try_to_optimize_kprobe(p) do {} while (0)
#define __arm_kprobe(p) arch_arm_kprobe(p)
#define __disarm_kprobe(p, o) arch_disarm_kprobe(p)
#define kprobe_disarmed(p) kprobe_disabled(p)
#define wait_for_kprobe_optimizer() do {} while (0)
/* There should be no unused kprobes can be reused without optimization */
static void reuse_unused_kprobe(struct kprobe *ap)
{
printk(KERN_ERR "Error: There should be no unused kprobe here.\n");
BUG_ON(kprobe_unused(ap));
}
static void free_aggr_kprobe(struct kprobe *p)
{
arch_remove_kprobe(p);
kfree(p);
}
static struct kprobe *alloc_aggr_kprobe(struct kprobe *p)
{
return kzalloc(sizeof(struct kprobe), GFP_KERNEL);
}
#endif /* CONFIG_OPTPROBES */
#ifdef CONFIG_KPROBES_ON_FTRACE
static struct ftrace_ops kprobe_ftrace_ops __read_mostly = {
.func = kprobe_ftrace_handler,
.flags = FTRACE_OPS_FL_SAVE_REGS,
};
static int kprobe_ftrace_enabled;
/* Must ensure p->addr is really on ftrace */
static int prepare_kprobe(struct kprobe *p)
{
if (!kprobe_ftrace(p))
return arch_prepare_kprobe(p);
return arch_prepare_kprobe_ftrace(p);
}
/* Caller must lock kprobe_mutex */
static void arm_kprobe_ftrace(struct kprobe *p)
{
int ret;
ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
(unsigned long)p->addr, 0, 0);
WARN(ret < 0, "Failed to arm kprobe-ftrace at %p (%d)\n", p->addr, ret);
kprobe_ftrace_enabled++;
if (kprobe_ftrace_enabled == 1) {
ret = register_ftrace_function(&kprobe_ftrace_ops);
WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
}
}
/* Caller must lock kprobe_mutex */
static void disarm_kprobe_ftrace(struct kprobe *p)
{
int ret;
kprobe_ftrace_enabled--;
if (kprobe_ftrace_enabled == 0) {
ret = unregister_ftrace_function(&kprobe_ftrace_ops);
WARN(ret < 0, "Failed to init kprobe-ftrace (%d)\n", ret);
}
ret = ftrace_set_filter_ip(&kprobe_ftrace_ops,
(unsigned long)p->addr, 1, 0);
WARN(ret < 0, "Failed to disarm kprobe-ftrace at %p (%d)\n", p->addr, ret);
}
#else /* !CONFIG_KPROBES_ON_FTRACE */
#define prepare_kprobe(p) arch_prepare_kprobe(p)
#define arm_kprobe_ftrace(p) do {} while (0)
#define disarm_kprobe_ftrace(p) do {} while (0)
#endif
/* Arm a kprobe with text_mutex */
static void arm_kprobe(struct kprobe *kp)
{
if (unlikely(kprobe_ftrace(kp))) {
arm_kprobe_ftrace(kp);
return;
}
/*
* Here, since __arm_kprobe() doesn't use stop_machine(),
* this doesn't cause deadlock on text_mutex. So, we don't
* need get_online_cpus().
*/
mutex_lock(&text_mutex);
__arm_kprobe(kp);
mutex_unlock(&text_mutex);
}
/* Disarm a kprobe with text_mutex */
static void disarm_kprobe(struct kprobe *kp, bool reopt)
{
if (unlikely(kprobe_ftrace(kp))) {
disarm_kprobe_ftrace(kp);
return;
}
/* Ditto */
mutex_lock(&text_mutex);
__disarm_kprobe(kp, reopt);
mutex_unlock(&text_mutex);
}
/*
* Aggregate handlers for multiple kprobes support - these handlers
* take care of invoking the individual kprobe handlers on p->list
*/
static int 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 && likely(!kprobe_disabled(kp))) {
set_kprobe_instance(kp);
if (kp->pre_handler(kp, regs))
return 1;
}
reset_kprobe_instance();
}
return 0;
}
NOKPROBE_SYMBOL(aggr_pre_handler);
static void 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 && likely(!kprobe_disabled(kp))) {
set_kprobe_instance(kp);
kp->post_handler(kp, regs, flags);
reset_kprobe_instance();
}
}
}
NOKPROBE_SYMBOL(aggr_post_handler);
static int aggr_fault_handler(struct kprobe *p, struct pt_regs *regs,
int trapnr)
{
struct kprobe *cur = __this_cpu_read(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;
}
NOKPROBE_SYMBOL(aggr_fault_handler);
static int aggr_break_handler(struct kprobe *p, struct pt_regs *regs)
{
struct kprobe *cur = __this_cpu_read(kprobe_instance);
int ret = 0;
if (cur && cur->break_handler) {
if (cur->break_handler(cur, regs))
ret = 1;
}
reset_kprobe_instance();
return ret;
}
NOKPROBE_SYMBOL(aggr_break_handler);
/* Walks the list and increments nmissed count for multiprobe case */
void kprobes_inc_nmissed_count(struct kprobe *p)
{
struct kprobe *kp;
if (!kprobe_aggrprobe(p)) {
p->nmissed++;
} else {
list_for_each_entry_rcu(kp, &p->list, list)
kp->nmissed++;
}
return;
}
NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
void recycle_rp_inst(struct kretprobe_instance *ri,
struct hlist_head *head)
{
struct kretprobe *rp = ri->rp;
/* remove rp inst off the rprobe_inst_table */
hlist_del(&ri->hlist);
INIT_HLIST_NODE(&ri->hlist);
if (likely(rp)) {
raw_spin_lock(&rp->lock);
hlist_add_head(&ri->hlist, &rp->free_instances);
raw_spin_unlock(&rp->lock);
} else
/* Unregistering */
hlist_add_head(&ri->hlist, head);
}
NOKPROBE_SYMBOL(recycle_rp_inst);
void kretprobe_hash_lock(struct task_struct *tsk,
struct hlist_head **head, unsigned long *flags)
__acquires(hlist_lock)
{
unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
raw_spinlock_t *hlist_lock;
*head = &kretprobe_inst_table[hash];
hlist_lock = kretprobe_table_lock_ptr(hash);
raw_spin_lock_irqsave(hlist_lock, *flags);
}
NOKPROBE_SYMBOL(kretprobe_hash_lock);
static void kretprobe_table_lock(unsigned long hash,
unsigned long *flags)
__acquires(hlist_lock)
{
raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
raw_spin_lock_irqsave(hlist_lock, *flags);
}
NOKPROBE_SYMBOL(kretprobe_table_lock);
void kretprobe_hash_unlock(struct task_struct *tsk,
unsigned long *flags)
__releases(hlist_lock)
{
unsigned long hash = hash_ptr(tsk, KPROBE_HASH_BITS);
raw_spinlock_t *hlist_lock;
hlist_lock = kretprobe_table_lock_ptr(hash);
raw_spin_unlock_irqrestore(hlist_lock, *flags);
}
NOKPROBE_SYMBOL(kretprobe_hash_unlock);
static void kretprobe_table_unlock(unsigned long hash,
unsigned long *flags)
__releases(hlist_lock)
{
raw_spinlock_t *hlist_lock = kretprobe_table_lock_ptr(hash);
raw_spin_unlock_irqrestore(hlist_lock, *flags);
}
NOKPROBE_SYMBOL(kretprobe_table_unlock);
/*
* 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 kprobe_flush_task(struct task_struct *tk)
{
struct kretprobe_instance *ri;
struct hlist_head *head, empty_rp;
struct hlist_node *tmp;
unsigned long hash, flags = 0;
if (unlikely(!kprobes_initialized))
/* Early boot. kretprobe_table_locks not yet initialized. */
return;
INIT_HLIST_HEAD(&empty_rp);
hash = hash_ptr(tk, KPROBE_HASH_BITS);
head = &kretprobe_inst_table[hash];
kretprobe_table_lock(hash, &flags);
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task == tk)
recycle_rp_inst(ri, &empty_rp);
}
kretprobe_table_unlock(hash, &flags);
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
}
NOKPROBE_SYMBOL(kprobe_flush_task);
static inline void free_rp_inst(struct kretprobe *rp)
{
struct kretprobe_instance *ri;
struct hlist_node *next;
hlist_for_each_entry_safe(ri, next, &rp->free_instances, hlist) {
hlist_del(&ri->hlist);
kfree(ri);
}
}
static void cleanup_rp_inst(struct kretprobe *rp)
{
unsigned long flags, hash;
struct kretprobe_instance *ri;
struct hlist_node *next;
struct hlist_head *head;
/* No race here */
for (hash = 0; hash < KPROBE_TABLE_SIZE; hash++) {
kretprobe_table_lock(hash, &flags);
head = &kretprobe_inst_table[hash];
hlist_for_each_entry_safe(ri, next, head, hlist) {
if (ri->rp == rp)
ri->rp = NULL;
}
kretprobe_table_unlock(hash, &flags);
}
free_rp_inst(rp);
}
NOKPROBE_SYMBOL(cleanup_rp_inst);
/*
* Add the new probe to ap->list. Fail if this is the
* second jprobe at the address - two jprobes can't coexist
*/
static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
{
BUG_ON(kprobe_gone(ap) || kprobe_gone(p));
if (p->break_handler || p->post_handler)
unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */
if (p->break_handler) {
if (ap->break_handler)
return -EEXIST;
list_add_tail_rcu(&p->list, &ap->list);
ap->break_handler = aggr_break_handler;
} else
list_add_rcu(&p->list, &ap->list);
if (p->post_handler && !ap->post_handler)
ap->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 void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
{
/* Copy p's insn slot to ap */
copy_kprobe(p, ap);
flush_insn_slot(ap);
ap->addr = p->addr;
ap->flags = p->flags & ~KPROBE_FLAG_OPTIMIZED;
ap->pre_handler = aggr_pre_handler;
ap->fault_handler = aggr_fault_handler;
/* We don't care the kprobe which has gone. */
if (p->post_handler && !kprobe_gone(p))
ap->post_handler = aggr_post_handler;
if (p->break_handler && !kprobe_gone(p))
ap->break_handler = aggr_break_handler;
INIT_LIST_HEAD(&ap->list);
INIT_HLIST_NODE(&ap->hlist);
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 register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
{
int ret = 0;
struct kprobe *ap = orig_p;
/* For preparing optimization, jump_label_text_reserved() is called */
jump_label_lock();
/*
* Get online CPUs to avoid text_mutex deadlock.with stop machine,
* which is invoked by unoptimize_kprobe() in add_new_kprobe()
*/
get_online_cpus();
mutex_lock(&text_mutex);
if (!kprobe_aggrprobe(orig_p)) {
/* If orig_p is not an aggr_kprobe, create new aggr_kprobe. */
ap = alloc_aggr_kprobe(orig_p);
if (!ap) {
ret = -ENOMEM;
goto out;
}
init_aggr_kprobe(ap, orig_p);
} else if (kprobe_unused(ap))
/* This probe is going to die. Rescue it */
reuse_unused_kprobe(ap);
if (kprobe_gone(ap)) {
/*
* Attempting to insert new probe at the same location that
* had a probe in the module vaddr area which already
* freed. So, the instruction slot has already been
* released. We need a new slot for the new probe.
*/
ret = arch_prepare_kprobe(ap);
if (ret)
/*
* Even if fail to allocate new slot, don't need to
* free aggr_probe. It will be used next time, or
* freed by unregister_kprobe.
*/
goto out;
/* Prepare optimized instructions if possible. */
prepare_optimized_kprobe(ap);
/*
* Clear gone flag to prevent allocating new slot again, and
* set disabled flag because it is not armed yet.
*/
ap->flags = (ap->flags & ~KPROBE_FLAG_GONE)
| KPROBE_FLAG_DISABLED;
}
/* Copy ap's insn slot to p */
copy_kprobe(ap, p);
ret = add_new_kprobe(ap, p);
out:
mutex_unlock(&text_mutex);
put_online_cpus();
jump_label_unlock();
if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
ap->flags &= ~KPROBE_FLAG_DISABLED;
if (!kprobes_all_disarmed)
/* Arm the breakpoint again. */
arm_kprobe(ap);
}
return ret;
}
bool __weak arch_within_kprobe_blacklist(unsigned long addr)
{
/* The __kprobes marked functions and entry code must not be probed */
return addr >= (unsigned long)__kprobes_text_start &&
addr < (unsigned long)__kprobes_text_end;
}
static bool within_kprobe_blacklist(unsigned long addr)
{
struct kprobe_blacklist_entry *ent;
if (arch_within_kprobe_blacklist(addr))
return true;
/*
* If there exists a kprobe_blacklist, verify and
* fail any probe registration in the prohibited area
*/
list_for_each_entry(ent, &kprobe_blacklist, list) {
if (addr >= ent->start_addr && addr < ent->end_addr)
return true;
}
return false;
}
/*
* 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.
* This returns encoded errors if it fails to look up symbol or invalid
* combination of parameters.
*/
static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
{
kprobe_opcode_t *addr = p->addr;
if ((p->symbol_name && p->addr) ||
(!p->symbol_name && !p->addr))
goto invalid;
if (p->symbol_name) {
kprobe_lookup_name(p->symbol_name, addr);
if (!addr)
return ERR_PTR(-ENOENT);
}
addr = (kprobe_opcode_t *)(((char *)addr) + p->offset);
if (addr)
return addr;
invalid:
return ERR_PTR(-EINVAL);
}
/* Check passed kprobe is valid and return kprobe in kprobe_table. */
static struct kprobe *__get_valid_kprobe(struct kprobe *p)
{
struct kprobe *ap, *list_p;
ap = get_kprobe(p->addr);
if (unlikely(!ap))
return NULL;
if (p != ap) {
list_for_each_entry_rcu(list_p, &ap->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid;
return NULL;
}
valid:
return ap;
}
/* Return error if the kprobe is being re-registered */
static inline int check_kprobe_rereg(struct kprobe *p)
{
int ret = 0;
mutex_lock(&kprobe_mutex);
if (__get_valid_kprobe(p))
ret = -EINVAL;
mutex_unlock(&kprobe_mutex);
return ret;
}
static int check_kprobe_address_safe(struct kprobe *p,
struct module **probed_mod)
{
int ret = 0;
unsigned long ftrace_addr;
/*
* If the address is located on a ftrace nop, set the
* breakpoint to the following instruction.
*/
ftrace_addr = ftrace_location((unsigned long)p->addr);
if (ftrace_addr) {
#ifdef CONFIG_KPROBES_ON_FTRACE
/* Given address is not on the instruction boundary */
if ((unsigned long)p->addr != ftrace_addr)
return -EILSEQ;
p->flags |= KPROBE_FLAG_FTRACE;
#else /* !CONFIG_KPROBES_ON_FTRACE */
return -EINVAL;
#endif
}
jump_label_lock();
preempt_disable();
/* Ensure it is not in reserved area nor out of text */
if (!kernel_text_address((unsigned long) p->addr) ||
within_kprobe_blacklist((unsigned long) p->addr) ||
jump_label_text_reserved(p->addr, p->addr)) {
ret = -EINVAL;
goto out;
}
/* Check if are we probing a module */
*probed_mod = __module_text_address((unsigned long) p->addr);
if (*probed_mod) {
/*
* We must hold a refcount of the probed module while updating
* its code to prohibit unexpected unloading.
*/
if (unlikely(!try_module_get(*probed_mod))) {
ret = -ENOENT;
goto out;
}
/*
* If the module freed .init.text, we couldn't insert
* kprobes in there.
*/
if (within_module_init((unsigned long)p->addr, *probed_mod) &&
(*probed_mod)->state != MODULE_STATE_COMING) {
module_put(*probed_mod);
*probed_mod = NULL;
ret = -ENOENT;
}
}
out:
preempt_enable();
jump_label_unlock();
return ret;
}
int register_kprobe(struct kprobe *p)
{
int ret;
struct kprobe *old_p;
struct module *probed_mod;
kprobe_opcode_t *addr;
/* Adjust probe address from symbol */
addr = kprobe_addr(p);
if (IS_ERR(addr))
return PTR_ERR(addr);
p->addr = addr;
ret = check_kprobe_rereg(p);
if (ret)
return ret;
/* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */
p->flags &= KPROBE_FLAG_DISABLED;
p->nmissed = 0;
INIT_LIST_HEAD(&p->list);
ret = check_kprobe_address_safe(p, &probed_mod);
if (ret)
return ret;
mutex_lock(&kprobe_mutex);
old_p = get_kprobe(p->addr);
if (old_p) {
/* Since this may unoptimize old_p, locking text_mutex. */
ret = register_aggr_kprobe(old_p, p);
goto out;
}
mutex_lock(&text_mutex); /* Avoiding text modification */
ret = prepare_kprobe(p);
mutex_unlock(&text_mutex);
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 (!kprobes_all_disarmed && !kprobe_disabled(p))
arm_kprobe(p);
/* Try to optimize kprobe */
try_to_optimize_kprobe(p);
out:
mutex_unlock(&kprobe_mutex);
if (probed_mod)
module_put(probed_mod);
return ret;
}
EXPORT_SYMBOL_GPL(register_kprobe);
/* Check if all probes on the aggrprobe are disabled */
static int aggr_kprobe_disabled(struct kprobe *ap)
{
struct kprobe *kp;
list_for_each_entry_rcu(kp, &ap->list, list)
if (!kprobe_disabled(kp))
/*
* There is an active probe on the list.
* We can't disable this ap.
*/
return 0;
return 1;
}
/* Disable one kprobe: Make sure called under kprobe_mutex is locked */
static struct kprobe *__disable_kprobe(struct kprobe *p)
{
struct kprobe *orig_p;
/* Get an original kprobe for return */
orig_p = __get_valid_kprobe(p);
if (unlikely(orig_p == NULL))
return NULL;
if (!kprobe_disabled(p)) {
/* Disable probe if it is a child probe */
if (p != orig_p)
p->flags |= KPROBE_FLAG_DISABLED;
/* Try to disarm and disable this/parent probe */
if (p == orig_p || aggr_kprobe_disabled(orig_p)) {
disarm_kprobe(orig_p, true);
orig_p->flags |= KPROBE_FLAG_DISABLED;
}
}
return orig_p;
}
/*
* Unregister a kprobe without a scheduler synchronization.
*/
static int __unregister_kprobe_top(struct kprobe *p)
{
struct kprobe *ap, *list_p;
/* Disable kprobe. This will disarm it if needed. */
ap = __disable_kprobe(p);
if (ap == NULL)
return -EINVAL;
if (ap == p)
/*
* This probe is an independent(and non-optimized) kprobe
* (not an aggrprobe). Remove from the hash list.
*/
goto disarmed;
/* Following process expects this probe is an aggrprobe */
WARN_ON(!kprobe_aggrprobe(ap));
if (list_is_singular(&ap->list) && kprobe_disarmed(ap))
/*
* !disarmed could be happen if the probe is under delayed
* unoptimizing.
*/
goto disarmed;
else {
/* If disabling probe has special handlers, update aggrprobe */
if (p->break_handler && !kprobe_gone(p))
ap->break_handler = NULL;
if (p->post_handler && !kprobe_gone(p)) {
list_for_each_entry_rcu(list_p, &ap->list, list) {
if ((list_p != p) && (list_p->post_handler))
goto noclean;
}
ap->post_handler = NULL;
}
noclean:
/*
* Remove from the aggrprobe: this path will do nothing in
* __unregister_kprobe_bottom().
*/
list_del_rcu(&p->list);
if (!kprobe_disabled(ap) && !kprobes_all_disarmed)
/*
* Try to optimize this probe again, because post
* handler may have been changed.
*/
optimize_kprobe(ap);
}
return 0;
disarmed:
BUG_ON(!kprobe_disarmed(ap));
hlist_del_rcu(&ap->hlist);
return 0;
}
static void __unregister_kprobe_bottom(struct kprobe *p)
{
struct kprobe *ap;
if (list_empty(&p->list))
/* This is an independent kprobe */
arch_remove_kprobe(p);
else if (list_is_singular(&p->list)) {
/* This is the last child of an aggrprobe */
ap = list_entry(p->list.next, struct kprobe, list);
list_del(&p->list);
free_aggr_kprobe(ap);
}
/* Otherwise, do nothing. */
}
int register_kprobes(struct kprobe **kps, int num)
{
int i, ret = 0;
if (num <= 0)
return -EINVAL;
for (i = 0; i < num; i++) {
ret = register_kprobe(kps[i]);
if (ret < 0) {
if (i > 0)
unregister_kprobes(kps, i);
break;
}
}
return ret;
}
EXPORT_SYMBOL_GPL(register_kprobes);
void unregister_kprobe(struct kprobe *p)
{
unregister_kprobes(&p, 1);
}
EXPORT_SYMBOL_GPL(unregister_kprobe);
void 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]);
}
EXPORT_SYMBOL_GPL(unregister_kprobes);
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;
}
int register_jprobes(struct jprobe **jps, int num)
{
struct jprobe *jp;
int ret = 0, i;
if (num <= 0)
return -EINVAL;
for (i = 0; i < num; i++) {
unsigned long addr, offset;
jp = jps[i];
addr = arch_deref_entry_point(jp->entry);
/* Verify probepoint is a function entry point */
if (kallsyms_lookup_size_offset(addr, NULL, &offset) &&
offset == 0) {
jp->kp.pre_handler = setjmp_pre_handler;
jp->kp.break_handler = longjmp_break_handler;
ret = register_kprobe(&jp->kp);
} else
ret = -EINVAL;
if (ret < 0) {
if (i > 0)
unregister_jprobes(jps, i);
break;
}
}
return ret;
}
EXPORT_SYMBOL_GPL(register_jprobes);
int register_jprobe(struct jprobe *jp)
{
return register_jprobes(&jp, 1);
}
EXPORT_SYMBOL_GPL(register_jprobe);
void unregister_jprobe(struct jprobe *jp)
{
unregister_jprobes(&jp, 1);
}
EXPORT_SYMBOL_GPL(unregister_jprobe);
void 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);
}
}
EXPORT_SYMBOL_GPL(unregister_jprobes);
#ifdef CONFIG_KRETPROBES
/*
* This kprobe pre_handler is registered with every kretprobe. When probe
* hits it will set up the return probe.
*/
static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
{
struct kretprobe *rp = container_of(p, struct kretprobe, kp);
unsigned long hash, flags = 0;
struct kretprobe_instance *ri;
/*TODO: consider to only swap the RA after the last pre_handler fired */
hash = hash_ptr(current, KPROBE_HASH_BITS);
raw_spin_lock_irqsave(&rp->lock, flags);
if (!hlist_empty(&rp->free_instances)) {
ri = hlist_entry(rp->free_instances.first,
struct kretprobe_instance, hlist);
hlist_del(&ri->hlist);
raw_spin_unlock_irqrestore(&rp->lock, flags);
ri->rp = rp;
ri->task = current;
if (rp->entry_handler && rp->entry_handler(ri, regs)) {
raw_spin_lock_irqsave(&rp->lock, flags);
hlist_add_head(&ri->hlist, &rp->free_instances);
raw_spin_unlock_irqrestore(&rp->lock, flags);
return 0;
}
arch_prepare_kretprobe(ri, regs);
/* XXX(hch): why is there no hlist_move_head? */
INIT_HLIST_NODE(&ri->hlist);
kretprobe_table_lock(hash, &flags);
hlist_add_head(&ri->hlist, &kretprobe_inst_table[hash]);
kretprobe_table_unlock(hash, &flags);
} else {
rp->nmissed++;
raw_spin_unlock_irqrestore(&rp->lock, flags);
}
return 0;
}
NOKPROBE_SYMBOL(pre_handler_kretprobe);
int register_kretprobe(struct kretprobe *rp)
{
int ret = 0;
struct kretprobe_instance *inst;
int i;
void *addr;
if (kretprobe_blacklist_size) {
addr = kprobe_addr(&rp->kp);
if (IS_ERR(addr))
return PTR_ERR(addr);
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_t(unsigned int, 10, 2*num_possible_cpus());
#else
rp->maxactive = num_possible_cpus();
#endif
}
raw_spin_lock_init(&rp->lock);
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->hlist);
hlist_add_head(&inst->hlist, &rp->free_instances);
}
rp->nmissed = 0;
/* Establish function entry probe point */
ret = register_kprobe(&rp->kp);
if (ret != 0)
free_rp_inst(rp);
return ret;
}
EXPORT_SYMBOL_GPL(register_kretprobe);
int register_kretprobes(struct kretprobe **rps, int num)
{
int ret = 0, i;
if (num <= 0)
return -EINVAL;
for (i = 0; i < num; i++) {
ret = register_kretprobe(rps[i]);
if (ret < 0) {
if (i > 0)
unregister_kretprobes(rps, i);
break;
}
}
return ret;
}
EXPORT_SYMBOL_GPL(register_kretprobes);
void unregister_kretprobe(struct kretprobe *rp)
{
unregister_kretprobes(&rp, 1);
}
EXPORT_SYMBOL_GPL(unregister_kretprobe);
void 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]);
}
}
}
EXPORT_SYMBOL_GPL(unregister_kretprobes);
#else /* CONFIG_KRETPROBES */
int register_kretprobe(struct kretprobe *rp)
{
return -ENOSYS;
}
EXPORT_SYMBOL_GPL(register_kretprobe);
int register_kretprobes(struct kretprobe **rps, int num)
{
return -ENOSYS;
}
EXPORT_SYMBOL_GPL(register_kretprobes);
void unregister_kretprobe(struct kretprobe *rp)
{
}
EXPORT_SYMBOL_GPL(unregister_kretprobe);
void unregister_kretprobes(struct kretprobe **rps, int num)
{
}
EXPORT_SYMBOL_GPL(unregister_kretprobes);
static int pre_handler_kretprobe(struct kprobe *p, struct pt_regs *regs)
{
return 0;
}
NOKPROBE_SYMBOL(pre_handler_kretprobe);
#endif /* CONFIG_KRETPROBES */
/* Set the kprobe gone and remove its instruction buffer. */
static void kill_kprobe(struct kprobe *p)
{
struct kprobe *kp;
p->flags |= KPROBE_FLAG_GONE;
if (kprobe_aggrprobe(p)) {
/*
* If this is an aggr_kprobe, we have to list all the
* chained probes and mark them GONE.
*/
list_for_each_entry_rcu(kp, &p->list, list)
kp->flags |= KPROBE_FLAG_GONE;
p->post_handler = NULL;
p->break_handler = NULL;
kill_optimized_kprobe(p);
}
/*
* Here, we can remove insn_slot safely, because no thread calls
* the original probed function (which will be freed soon) any more.
*/
arch_remove_kprobe(p);
}
/* Disable one kprobe */
int disable_kprobe(struct kprobe *kp)
{
int ret = 0;
mutex_lock(&kprobe_mutex);
/* Disable this kprobe */
if (__disable_kprobe(kp) == NULL)
ret = -EINVAL;
mutex_unlock(&kprobe_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(disable_kprobe);
/* Enable one kprobe */
int enable_kprobe(struct kprobe *kp)
{
int ret = 0;
struct kprobe *p;
mutex_lock(&kprobe_mutex);
/* Check whether specified probe is valid. */
p = __get_valid_kprobe(kp);
if (unlikely(p == NULL)) {
ret = -EINVAL;
goto out;
}
if (kprobe_gone(kp)) {
/* This kprobe has gone, we couldn't enable it. */
ret = -EINVAL;
goto out;
}
if (p != kp)
kp->flags &= ~KPROBE_FLAG_DISABLED;
if (!kprobes_all_disarmed && kprobe_disabled(p)) {
p->flags &= ~KPROBE_FLAG_DISABLED;
arm_kprobe(p);
}
out:
mutex_unlock(&kprobe_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(enable_kprobe);
void dump_kprobe(struct kprobe *kp)
{
printk(KERN_WARNING "Dumping kprobe:\n");
printk(KERN_WARNING "Name: %s\nAddress: %p\nOffset: %x\n",
kp->symbol_name, kp->addr, kp->offset);
}
NOKPROBE_SYMBOL(dump_kprobe);
/*
* Lookup and populate the kprobe_blacklist.
*
* Unlike the kretprobe blacklist, we'll need to determine
* the range of addresses that belong to the said functions,
* since a kprobe need not necessarily be at the beginning
* of a function.
*/
static int __init populate_kprobe_blacklist(unsigned long *start,
unsigned long *end)
{
unsigned long *iter;
struct kprobe_blacklist_entry *ent;
unsigned long entry, offset = 0, size = 0;
for (iter = start; iter < end; iter++) {
entry = arch_deref_entry_point((void *)*iter);
if (!kernel_text_address(entry) ||
!kallsyms_lookup_size_offset(entry, &size, &offset)) {
pr_err("Failed to find blacklist at %p\n",
(void *)entry);
continue;
}
ent = kmalloc(sizeof(*ent), GFP_KERNEL);
if (!ent)
return -ENOMEM;
ent->start_addr = entry;
ent->end_addr = entry + size;
INIT_LIST_HEAD(&ent->list);
list_add_tail(&ent->list, &kprobe_blacklist);
}
return 0;
}
/* Module notifier call back, checking kprobes on the module */
static int kprobes_module_callback(struct notifier_block *nb,
unsigned long val, void *data)
{
struct module *mod = data;
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
int checkcore = (val == MODULE_STATE_GOING);
if (val != MODULE_STATE_GOING && val != MODULE_STATE_LIVE)
return NOTIFY_DONE;
/*
* When MODULE_STATE_GOING was notified, both of module .text and
* .init.text sections would be freed. When MODULE_STATE_LIVE was
* notified, only .init.text section would be freed. We need to
* disable kprobes which have been inserted in the sections.
*/
mutex_lock(&kprobe_mutex);
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry_rcu(p, head, hlist)
if (within_module_init((unsigned long)p->addr, mod) ||
(checkcore &&
within_module_core((unsigned long)p->addr, mod))) {
/*
* The vaddr this probe is installed will soon
* be vfreed buy not synced to disk. Hence,
* disarming the breakpoint isn't needed.
*/
kill_kprobe(p);
}
}
mutex_unlock(&kprobe_mutex);
return NOTIFY_DONE;
}
static struct notifier_block kprobe_module_nb = {
.notifier_call = kprobes_module_callback,
.priority = 0
};
/* Markers of _kprobe_blacklist section */
extern unsigned long __start_kprobe_blacklist[];
extern unsigned long __stop_kprobe_blacklist[];
static int __init init_kprobes(void)
{
int i, err = 0;
/* FIXME allocate the probe table, currently defined statically */
/* initialize all list heads */
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
INIT_HLIST_HEAD(&kprobe_table[i]);
INIT_HLIST_HEAD(&kretprobe_inst_table[i]);
raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
}
err = populate_kprobe_blacklist(__start_kprobe_blacklist,
__stop_kprobe_blacklist);
if (err) {
pr_err("kprobes: failed to populate blacklist: %d\n", err);
pr_err("Please take care of using kprobes.\n");
}
if (kretprobe_blacklist_size) {
/* lookup the function address from its name */
for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
kprobe_lookup_name(kretprobe_blacklist[i].name,
kretprobe_blacklist[i].addr);
if (!kretprobe_blacklist[i].addr)
printk("kretprobe: lookup failed: %s\n",
kretprobe_blacklist[i].name);
}
}
#if defined(CONFIG_OPTPROBES)
#if defined(__ARCH_WANT_KPROBES_INSN_SLOT)
/* Init kprobe_optinsn_slots */
kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
#endif
/* By default, kprobes can be optimized */
kprobes_allow_optimization = true;
#endif
/* By default, kprobes are armed */
kprobes_all_disarmed = false;
err = arch_init_kprobes();
if (!err)
err = register_die_notifier(&kprobe_exceptions_nb);
if (!err)
err = register_module_notifier(&kprobe_module_nb);
kprobes_initialized = (err == 0);
if (!err)
init_test_probes();
return err;
}
#ifdef CONFIG_DEBUG_FS
static void report_probe(struct seq_file *pi, struct kprobe *p,
const char *sym, int offset, char *modname, struct kprobe *pp)
{
char *kprobe_type;
if (p->pre_handler == pre_handler_kretprobe)
kprobe_type = "r";
else if (p->pre_handler == setjmp_pre_handler)
kprobe_type = "j";
else
kprobe_type = "k";
if (sym)
seq_printf(pi, "%p %s %s+0x%x %s ",
p->addr, kprobe_type, sym, offset,
(modname ? modname : " "));
else
seq_printf(pi, "%p %s %p ",
p->addr, kprobe_type, p->addr);
if (!pp)
pp = p;
seq_printf(pi, "%s%s%s%s\n",
(kprobe_gone(p) ? "[GONE]" : ""),
((kprobe_disabled(p) && !kprobe_gone(p)) ? "[DISABLED]" : ""),
(kprobe_optimized(pp) ? "[OPTIMIZED]" : ""),
(kprobe_ftrace(pp) ? "[FTRACE]" : ""));
}
static void *kprobe_seq_start(struct seq_file *f, loff_t *pos)
{
return (*pos < KPROBE_TABLE_SIZE) ? pos : NULL;
}
static void *kprobe_seq_next(struct seq_file *f, void *v, loff_t *pos)
{
(*pos)++;
if (*pos >= KPROBE_TABLE_SIZE)
return NULL;
return pos;
}
static void kprobe_seq_stop(struct seq_file *f, void *v)
{
/* Nothing to do */
}
static int show_kprobe_addr(struct seq_file *pi, void *v)
{
struct hlist_head *head;
struct kprobe *p, *kp;
const char *sym = NULL;
unsigned int i = *(loff_t *) v;
unsigned long offset = 0;
char *modname, namebuf[KSYM_NAME_LEN];
head = &kprobe_table[i];
preempt_disable();
hlist_for_each_entry_rcu(p, head, hlist) {
sym = kallsyms_lookup((unsigned long)p->addr, NULL,
&offset, &modname, namebuf);
if (kprobe_aggrprobe(p)) {
list_for_each_entry_rcu(kp, &p->list, list)
report_probe(pi, kp, sym, offset, modname, p);
} else
report_probe(pi, p, sym, offset, modname, NULL);
}
preempt_enable();
return 0;
}
static const struct seq_operations kprobes_seq_ops = {
.start = kprobe_seq_start,
.next = kprobe_seq_next,
.stop = kprobe_seq_stop,
.show = show_kprobe_addr
};
static int kprobes_open(struct inode *inode, struct file *filp)
{
return seq_open(filp, &kprobes_seq_ops);
}
static const struct file_operations debugfs_kprobes_operations = {
.open = kprobes_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
/* kprobes/blacklist -- shows which functions can not be probed */
static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
{
return seq_list_start(&kprobe_blacklist, *pos);
}
static void *kprobe_blacklist_seq_next(struct seq_file *m, void *v, loff_t *pos)
{
return seq_list_next(v, &kprobe_blacklist, pos);
}
static int kprobe_blacklist_seq_show(struct seq_file *m, void *v)
{
struct kprobe_blacklist_entry *ent =
list_entry(v, struct kprobe_blacklist_entry, list);
seq_printf(m, "0x%p-0x%p\t%ps\n", (void *)ent->start_addr,
(void *)ent->end_addr, (void *)ent->start_addr);
return 0;
}
static const struct seq_operations kprobe_blacklist_seq_ops = {
.start = kprobe_blacklist_seq_start,
.next = kprobe_blacklist_seq_next,
.stop = kprobe_seq_stop, /* Reuse void function */
.show = kprobe_blacklist_seq_show,
};
static int kprobe_blacklist_open(struct inode *inode, struct file *filp)
{
return seq_open(filp, &kprobe_blacklist_seq_ops);
}
static const struct file_operations debugfs_kprobe_blacklist_ops = {
.open = kprobe_blacklist_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
};
static void arm_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
mutex_lock(&kprobe_mutex);
/* If kprobes are armed, just return */
if (!kprobes_all_disarmed)
goto already_enabled;
/* Arming kprobes doesn't optimize kprobe itself */
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry_rcu(p, head, hlist)
if (!kprobe_disabled(p))
arm_kprobe(p);
}
kprobes_all_disarmed = false;
printk(KERN_INFO "Kprobes globally enabled\n");
already_enabled:
mutex_unlock(&kprobe_mutex);
return;
}
static void disarm_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i;
mutex_lock(&kprobe_mutex);
/* If kprobes are already disarmed, just return */
if (kprobes_all_disarmed) {
mutex_unlock(&kprobe_mutex);
return;
}
kprobes_all_disarmed = true;
printk(KERN_INFO "Kprobes globally disabled\n");
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry_rcu(p, head, hlist) {
if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p))
disarm_kprobe(p, false);
}
}
mutex_unlock(&kprobe_mutex);
/* Wait for disarming all kprobes by optimizer */
wait_for_kprobe_optimizer();
}
/*
* XXX: The debugfs bool file interface doesn't allow for callbacks
* when the bool state is switched. We can reuse that facility when
* available
*/
static ssize_t read_enabled_file_bool(struct file *file,
char __user *user_buf, size_t count, loff_t *ppos)
{
char buf[3];
if (!kprobes_all_disarmed)
buf[0] = '1';
else
buf[0] = '0';
buf[1] = '\n';
buf[2] = 0x00;
return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}
static ssize_t write_enabled_file_bool(struct file *file,
const char __user *user_buf, size_t count, loff_t *ppos)
{
char buf[32];
size_t buf_size;
buf_size = min(count, (sizeof(buf)-1));
if (copy_from_user(buf, user_buf, buf_size))
return -EFAULT;
buf[buf_size] = '\0';
switch (buf[0]) {
case 'y':
case 'Y':
case '1':
arm_all_kprobes();
break;
case 'n':
case 'N':
case '0':
disarm_all_kprobes();
break;
default:
return -EINVAL;
}
return count;
}
static const struct file_operations fops_kp = {
.read = read_enabled_file_bool,
.write = write_enabled_file_bool,
.llseek = default_llseek,
};
static int __init debugfs_kprobe_init(void)
{
struct dentry *dir, *file;
unsigned int value = 1;
dir = debugfs_create_dir("kprobes", NULL);
if (!dir)
return -ENOMEM;
file = debugfs_create_file("list", 0444, dir, NULL,
&debugfs_kprobes_operations);
if (!file)
goto error;
file = debugfs_create_file("enabled", 0600, dir,
&value, &fops_kp);
if (!file)
goto error;
file = debugfs_create_file("blacklist", 0444, dir, NULL,
&debugfs_kprobe_blacklist_ops);
if (!file)
goto error;
return 0;
error:
debugfs_remove(dir);
return -ENOMEM;
}
late_initcall(debugfs_kprobe_init);
#endif /* CONFIG_DEBUG_FS */
module_init(init_kprobes);
/* defined in arch/.../kernel/kprobes.c */
EXPORT_SYMBOL_GPL(jprobe_return);
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