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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Kernel Probes (KProbes)
*
* 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.
*/
#define pr_fmt(fmt) "kprobes: " fmt
#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 <linux/static_call.h>
#include <linux/perf_event.h>
#include <asm/sections.h>
#include <asm/cacheflush.h>
#include <asm/errno.h>
#include <linux/uaccess.h>
#define KPROBE_HASH_BITS 6
#define KPROBE_TABLE_SIZE (1 << KPROBE_HASH_BITS)
static int kprobes_initialized;
/* kprobe_table can be accessed by
* - Normal hlist traversal and RCU add/del under 'kprobe_mutex' is held.
* Or
* - RCU hlist traversal under disabling preempt (breakpoint handlers)
*/
static struct hlist_head kprobe_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);
kprobe_opcode_t * __weak kprobe_lookup_name(const char *name,
unsigned int __unused)
{
return ((kprobe_opcode_t *)(kallsyms_lookup_name(name)));
}
/*
* Blacklist -- list of 'struct kprobe_blacklist_entry' to store info where
* kprobes can not probe.
*/
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,
};
void __weak *alloc_insn_page(void)
{
/*
* Use module_alloc() so this page is within +/- 2GB of where the
* kernel image and loaded module images reside. This is required
* for most of the architectures.
* (e.g. x86-64 needs this to handle the %rip-relative fixups.)
*/
return module_alloc(PAGE_SIZE);
}
static void free_insn_page(void *page)
{
module_memfree(page);
}
struct kprobe_insn_cache kprobe_insn_slots = {
.mutex = __MUTEX_INITIALIZER(kprobe_insn_slots.mutex),
.alloc = alloc_insn_page,
.free = free_insn_page,
.sym = KPROBE_INSN_PAGE_SYM,
.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;
/* Since the slot array is not protected by rcu, we need a mutex */
mutex_lock(&c->mutex);
retry:
rcu_read_lock();
list_for_each_entry_rcu(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);
rcu_read_unlock();
goto out;
}
}
/* kip->nused is broken. Fix it. */
kip->nused = slots_per_page(c);
WARN_ON(1);
}
}
rcu_read_unlock();
/* 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;
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_rcu(&kip->list, &c->pages);
slot = kip->insns;
/* Record the perf ksymbol register event after adding the page */
perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL, (unsigned long)kip->insns,
PAGE_SIZE, false, c->sym);
out:
mutex_unlock(&c->mutex);
return slot;
}
/* Return true if all garbages are collected, otherwise false. */
static bool 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)) {
/*
* Record perf ksymbol unregister event before removing
* the page.
*/
perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_OOL,
(unsigned long)kip->insns, PAGE_SIZE, true,
kip->cache->sym);
list_del_rcu(&kip->list);
synchronize_rcu();
kip->cache->free(kip->insns);
kfree(kip);
}
return true;
}
return false;
}
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_rcu();
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;
long idx;
mutex_lock(&c->mutex);
rcu_read_lock();
list_for_each_entry_rcu(kip, &c->pages, list) {
idx = ((long)slot - (long)kip->insns) /
(c->insn_size * sizeof(kprobe_opcode_t));
if (idx >= 0 && idx < slots_per_page(c))
goto out;
}
/* Could not find this slot. */
WARN_ON(1);
kip = NULL;
out:
rcu_read_unlock();
/* Mark and sweep: this may sleep */
if (kip) {
/* Check double free */
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);
}
}
mutex_unlock(&c->mutex);
}
/*
* Check given address is on the page of kprobe instruction slots.
* This will be used for checking whether the address on a stack
* is on a text area or not.
*/
bool __is_insn_slot_addr(struct kprobe_insn_cache *c, unsigned long addr)
{
struct kprobe_insn_page *kip;
bool ret = false;
rcu_read_lock();
list_for_each_entry_rcu(kip, &c->pages, list) {
if (addr >= (unsigned long)kip->insns &&
addr < (unsigned long)kip->insns + PAGE_SIZE) {
ret = true;
break;
}
}
rcu_read_unlock();
return ret;
}
int kprobe_cache_get_kallsym(struct kprobe_insn_cache *c, unsigned int *symnum,
unsigned long *value, char *type, char *sym)
{
struct kprobe_insn_page *kip;
int ret = -ERANGE;
rcu_read_lock();
list_for_each_entry_rcu(kip, &c->pages, list) {
if ((*symnum)--)
continue;
strscpy(sym, c->sym, KSYM_NAME_LEN);
*type = 't';
*value = (unsigned long)kip->insns;
ret = 0;
break;
}
rcu_read_unlock();
return ret;
}
#ifdef CONFIG_OPTPROBES
void __weak *alloc_optinsn_page(void)
{
return alloc_insn_page();
}
void __weak free_optinsn_page(void *page)
{
free_insn_page(page);
}
/* For optimized_kprobe buffer */
struct kprobe_insn_cache kprobe_optinsn_slots = {
.mutex = __MUTEX_INITIALIZER(kprobe_optinsn_slots.mutex),
.alloc = alloc_optinsn_page,
.free = free_optinsn_page,
.sym = KPROBE_OPTINSN_PAGE_SYM,
.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 architecture specific code.
*/
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,
lockdep_is_held(&kprobe_mutex)) {
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 'p' is an aggregator */
static inline bool kprobe_aggrprobe(struct kprobe *p)
{
return p->pre_handler == aggr_pre_handler;
}
/* Return true if 'p' is unused */
static inline bool 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: This is protected by 'kprobe_mutex'. */
static bool kprobes_allow_optimization;
/*
* Call all 'kprobe::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 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 if the kprobe is disarmed. Note: p must be on hash list */
static inline bool 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 if the probe is queued on (un)optimizing lists */
static bool 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 true;
}
return false;
}
/*
* Return an optimized kprobe whose optimizing code replaces
* instructions including 'addr' (exclude breakpoint).
*/
static struct kprobe *get_optimized_kprobe(kprobe_opcode_t *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 / sizeof(kprobe_opcode_t); i++)
p = get_kprobe(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)
{
lockdep_assert_held(&text_mutex);
/*
* The optimization/unoptimization refers 'online_cpus' via
* stop_machine() and cpu-hotplug modifies the 'online_cpus'.
* And same time, 'text_mutex' will be held in cpu-hotplug and here.
* This combination can cause a deadlock (cpu-hotplug tries to lock
* 'text_mutex' but stop_machine() can not be done because
* the 'online_cpus' has been changed)
* To avoid this deadlock, caller must have locked cpu-hotplug
* for preventing cpu-hotplug outside of 'text_mutex' locking.
*/
lockdep_assert_cpus_held();
/* Optimization never be done when disarmed */
if (kprobes_all_disarmed || !kprobes_allow_optimization ||
list_empty(&optimizing_list))
return;
arch_optimize_kprobes(&optimizing_list);
}
/*
* 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;
lockdep_assert_held(&text_mutex);
/* See comment in do_optimize_kprobes() */
lockdep_assert_cpus_held();
/* Unoptimization must be done anytime */
if (list_empty(&unoptimizing_list))
return;
arch_unoptimize_kprobes(&unoptimizing_list, &freeing_list);
/* Loop on 'freeing_list' for disarming */
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
/* Switching from detour code to origin */
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
/* 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);
}
}
/* Reclaim all kprobes on the 'freeing_list' */
static void do_free_cleaned_kprobes(void)
{
struct optimized_kprobe *op, *tmp;
list_for_each_entry_safe(op, tmp, &freeing_list, list) {
list_del_init(&op->list);
if (WARN_ON_ONCE(!kprobe_unused(&op->kp))) {
/*
* This must not happen, but if there is a kprobe
* still in use, keep it on kprobes hash list.
*/
continue;
}
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);
cpus_read_lock();
mutex_lock(&text_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 potentially
* preempted tasks to have normally scheduled. Because optprobe
* may modify multiple instructions, there is a chance that Nth
* instruction is preempted. In that case, such tasks can return
* to 2nd-Nth byte of jump instruction. This wait is for avoiding it.
* Note that on non-preemptive kernel, this is transparently converted
* to synchronoze_sched() to wait for all interrupts to have completed.
*/
synchronize_rcu_tasks();
/* Step 3: Optimize kprobes after quiesence period */
do_optimize_kprobes();
/* Step 4: Free cleaned kprobes after quiesence period */
do_free_cleaned_kprobes();
mutex_unlock(&text_mutex);
cpus_read_unlock();
/* Step 5: Kick optimizer again if needed */
if (!list_empty(&optimizing_list) || !list_empty(&unoptimizing_list))
kick_kprobe_optimizer();
mutex_unlock(&kprobe_mutex);
}
/* Wait for completing optimization and unoptimization */
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);
}
static bool optprobe_queued_unopt(struct optimized_kprobe *op)
{
struct optimized_kprobe *_op;
list_for_each_entry(_op, &unoptimizing_list, list) {
if (op == _op)
return true;
}
return false;
}
/* 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;
/* kprobes with 'post_handler' can not be optimized */
if (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) {
if (optprobe_queued_unopt(op)) {
/* This is under unoptimizing. Just dequeue the probe */
list_del_init(&op->list);
}
return;
}
op->kp.flags |= KPROBE_FLAG_OPTIMIZED;
/*
* On the 'unoptimizing_list' and 'optimizing_list',
* 'op' must have OPTIMIZED flag
*/
if (WARN_ON_ONCE(!list_empty(&op->list)))
return;
list_add(&op->list, &optimizing_list);
kick_kprobe_optimizer();
}
/* Short cut to direct unoptimizing */
static void force_unoptimize_kprobe(struct optimized_kprobe *op)
{
lockdep_assert_cpus_held();
arch_unoptimize_kprobe(op);
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
}
/* 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))
return;
if (!list_empty(&op->list)) {
if (optprobe_queued_unopt(op)) {
/* Queued in unoptimizing queue */
if (force) {
/*
* Forcibly unoptimize the kprobe here, and queue it
* in the freeing list for release afterwards.
*/
force_unoptimize_kprobe(op);
list_move(&op->list, &freeing_list);
}
} else {
/* Dequeue from the optimizing queue */
list_del_init(&op->list);
op->kp.flags &= ~KPROBE_FLAG_OPTIMIZED;
}
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 int reuse_unused_kprobe(struct kprobe *ap)
{
struct optimized_kprobe *op;
/*
* 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);
WARN_ON_ONCE(list_empty(&op->list));
/* Enable the probe again */
ap->flags &= ~KPROBE_FLAG_DISABLED;
/* Optimize it again. (remove from 'op->list') */
if (!kprobe_optready(ap))
return -EINVAL;
optimize_kprobe(ap);
return 0;
}
/* 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);
}
static inline
void __prepare_optimized_kprobe(struct optimized_kprobe *op, struct kprobe *p)
{
if (!kprobe_ftrace(p))
arch_prepare_optimized_kprobe(op, p);
}
/* 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);
__prepare_optimized_kprobe(op, p);
}
/* 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;
__prepare_optimized_kprobe(op, p);
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. */
cpus_read_lock();
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();
cpus_read_unlock();
}
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;
cpus_read_lock();
kprobes_allow_optimization = true;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry(p, head, hlist)
if (!kprobe_disabled(p))
optimize_kprobe(p);
}
cpus_read_unlock();
pr_info("kprobe jump-optimization is enabled. All kprobes are optimized if possible.\n");
out:
mutex_unlock(&kprobe_mutex);
}
#ifdef CONFIG_SYSCTL
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;
}
cpus_read_lock();
kprobes_allow_optimization = false;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry(p, head, hlist) {
if (!kprobe_disabled(p))
unoptimize_kprobe(p, false);
}
}
cpus_read_unlock();
mutex_unlock(&kprobe_mutex);
/* Wait for unoptimizing completion. */
wait_for_kprobe_optimizer();
pr_info("kprobe jump-optimization is disabled. All kprobes are based on software breakpoint.\n");
}
static DEFINE_MUTEX(kprobe_sysctl_mutex);
int sysctl_kprobes_optimization;
int proc_kprobes_optimization_handler(struct ctl_table *table, int write,
void *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. */
static void __arm_kprobe(struct kprobe *p)
{
struct kprobe *_p;
lockdep_assert_held(&text_mutex);
/* Find the overlapping optimized kprobes. */
_p = get_optimized_kprobe(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. */
static void __disarm_kprobe(struct kprobe *p, bool reopt)
{
struct kprobe *_p;
lockdep_assert_held(&text_mutex);
/* Try to unoptimize */
unoptimize_kprobe(p, kprobes_all_disarmed);
if (!kprobe_queued(p)) {
arch_disarm_kprobe(p);
/* If another kprobe was blocked, re-optimize it. */
_p = get_optimized_kprobe(p->addr);
if (unlikely(_p) && reopt)
optimize_kprobe(_p);
}
/*
* TODO: Since unoptimization and real disarming will be done by
* the worker thread, we can not check whether another probe are
* unoptimized because of this probe here. It should be re-optimized
* by the worker thread.
*/
}
#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)
static int reuse_unused_kprobe(struct kprobe *ap)
{
/*
* If the optimized kprobe is NOT supported, the aggr kprobe is
* released at the same time that the last aggregated kprobe is
* unregistered.
* Thus there should be no chance to reuse unused kprobe.
*/
WARN_ON_ONCE(1);
return -EINVAL;
}
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 struct ftrace_ops kprobe_ipmodify_ops __read_mostly = {
.func = kprobe_ftrace_handler,
.flags = FTRACE_OPS_FL_SAVE_REGS | FTRACE_OPS_FL_IPMODIFY,
};
static int kprobe_ipmodify_enabled;
static int kprobe_ftrace_enabled;
static int __arm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
int *cnt)
{
int ret = 0;
lockdep_assert_held(&kprobe_mutex);
ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 0, 0);
if (WARN_ONCE(ret < 0, "Failed to arm kprobe-ftrace at %pS (error %d)\n", p->addr, ret))
return ret;
if (*cnt == 0) {
ret = register_ftrace_function(ops);
if (WARN(ret < 0, "Failed to register kprobe-ftrace (error %d)\n", ret))
goto err_ftrace;
}
(*cnt)++;
return ret;
err_ftrace:
/*
* At this point, sinec ops is not registered, we should be sefe from
* registering empty filter.
*/
ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
return ret;
}
static int arm_kprobe_ftrace(struct kprobe *p)
{
bool ipmodify = (p->post_handler != NULL);
return __arm_kprobe_ftrace(p,
ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
}
static int __disarm_kprobe_ftrace(struct kprobe *p, struct ftrace_ops *ops,
int *cnt)
{
int ret = 0;
lockdep_assert_held(&kprobe_mutex);
if (*cnt == 1) {
ret = unregister_ftrace_function(ops);
if (WARN(ret < 0, "Failed to unregister kprobe-ftrace (error %d)\n", ret))
return ret;
}
(*cnt)--;
ret = ftrace_set_filter_ip(ops, (unsigned long)p->addr, 1, 0);
WARN_ONCE(ret < 0, "Failed to disarm kprobe-ftrace at %pS (error %d)\n",
p->addr, ret);
return ret;
}
static int disarm_kprobe_ftrace(struct kprobe *p)
{
bool ipmodify = (p->post_handler != NULL);
return __disarm_kprobe_ftrace(p,
ipmodify ? &kprobe_ipmodify_ops : &kprobe_ftrace_ops,
ipmodify ? &kprobe_ipmodify_enabled : &kprobe_ftrace_enabled);
}
#else /* !CONFIG_KPROBES_ON_FTRACE */
static inline int arm_kprobe_ftrace(struct kprobe *p)
{
return -ENODEV;
}
static inline int disarm_kprobe_ftrace(struct kprobe *p)
{
return -ENODEV;
}
#endif
static int prepare_kprobe(struct kprobe *p)
{
/* Must ensure p->addr is really on ftrace */
if (kprobe_ftrace(p))
return arch_prepare_kprobe_ftrace(p);
return arch_prepare_kprobe(p);
}
static int arm_kprobe(struct kprobe *kp)
{
if (unlikely(kprobe_ftrace(kp)))
return arm_kprobe_ftrace(kp);
cpus_read_lock();
mutex_lock(&text_mutex);
__arm_kprobe(kp);
mutex_unlock(&text_mutex);
cpus_read_unlock();
return 0;
}
static int disarm_kprobe(struct kprobe *kp, bool reopt)
{
if (unlikely(kprobe_ftrace(kp)))
return disarm_kprobe_ftrace(kp);
cpus_read_lock();
mutex_lock(&text_mutex);
__disarm_kprobe(kp, reopt);
mutex_unlock(&text_mutex);
cpus_read_unlock();
return 0;
}
/*
* 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);
/* Walks the list and increments 'nmissed' if 'p' has child probes. */
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++;
}
}
NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);
static void free_rp_inst_rcu(struct rcu_head *head)
{
struct kretprobe_instance *ri = container_of(head, struct kretprobe_instance, rcu);
if (refcount_dec_and_test(&ri->rph->ref))
kfree(ri->rph);
kfree(ri);
}
NOKPROBE_SYMBOL(free_rp_inst_rcu);
static void recycle_rp_inst(struct kretprobe_instance *ri)
{
struct kretprobe *rp = get_kretprobe(ri);
if (likely(rp))
freelist_add(&ri->freelist, &rp->freelist);
else
call_rcu(&ri->rcu, free_rp_inst_rcu);
}
NOKPROBE_SYMBOL(recycle_rp_inst);
static struct kprobe kprobe_busy = {
.addr = (void *) get_kprobe,
};
void kprobe_busy_begin(void)
{
struct kprobe_ctlblk *kcb;
preempt_disable();
__this_cpu_write(current_kprobe, &kprobe_busy);
kcb = get_kprobe_ctlblk();
kcb->kprobe_status = KPROBE_HIT_ACTIVE;
}
void kprobe_busy_end(void)
{
__this_cpu_write(current_kprobe, NULL);
preempt_enable();
}
/*
* This function is called from delayed_put_task_struct() when a task is
* dead and cleaned up to recycle any kretprobe 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 llist_node *node;
/* Early boot, not yet initialized. */
if (unlikely(!kprobes_initialized))
return;
kprobe_busy_begin();
node = __llist_del_all(&tk->kretprobe_instances);
while (node) {
ri = container_of(node, struct kretprobe_instance, llist);
node = node->next;
recycle_rp_inst(ri);
}
kprobe_busy_end();
}
NOKPROBE_SYMBOL(kprobe_flush_task);
static inline void free_rp_inst(struct kretprobe *rp)
{
struct kretprobe_instance *ri;
struct freelist_node *node;
int count = 0;
node = rp->freelist.head;
while (node) {
ri = container_of(node, struct kretprobe_instance, freelist);
node = node->next;
kfree(ri);
count++;
}
if (refcount_sub_and_test(count, &rp->rph->ref)) {
kfree(rp->rph);
rp->rph = NULL;
}
}
/* Add the new probe to 'ap->list'. */
static int add_new_kprobe(struct kprobe *ap, struct kprobe *p)
{
if (p->post_handler)
unoptimize_kprobe(ap, true); /* Fall back to normal kprobe */
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 aggregator kprobe. Replace the
* earlier kprobe in the hlist with the aggregator kprobe.
*/
static void init_aggr_kprobe(struct kprobe *ap, struct kprobe *p)
{
/* Copy the insn slot of 'p' 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;
/* We don't care the kprobe which has gone. */
if (p->post_handler && !kprobe_gone(p))
ap->post_handler = aggr_post_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 registers the second or subsequent kprobe at the same address.
*/
static int register_aggr_kprobe(struct kprobe *orig_p, struct kprobe *p)
{
int ret = 0;
struct kprobe *ap = orig_p;
cpus_read_lock();
/* For preparing optimization, jump_label_text_reserved() is called */
jump_label_lock();
mutex_lock(&text_mutex);
if (!kprobe_aggrprobe(orig_p)) {
/* If 'orig_p' is not an 'aggr_kprobe', create new one. */
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 */
ret = reuse_unused_kprobe(ap);
if (ret)
goto out;
}
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 the 'ap'. 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 the insn slot of 'p' to 'ap'. */
copy_kprobe(ap, p);
ret = add_new_kprobe(ap, p);
out:
mutex_unlock(&text_mutex);
jump_label_unlock();
cpus_read_unlock();
if (ret == 0 && kprobe_disabled(ap) && !kprobe_disabled(p)) {
ap->flags &= ~KPROBE_FLAG_DISABLED;
if (!kprobes_all_disarmed) {
/* Arm the breakpoint again. */
ret = arm_kprobe(ap);
if (ret) {
ap->flags |= KPROBE_FLAG_DISABLED;
list_del_rcu(&p->list);
synchronize_rcu();
}
}
}
return ret;
}
bool __weak arch_within_kprobe_blacklist(unsigned long addr)
{
/* The '__kprobes' 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 'kprobe_blacklist' is defined, check the address and
* reject 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;
}
bool within_kprobe_blacklist(unsigned long addr)
{
char symname[KSYM_NAME_LEN], *p;
if (__within_kprobe_blacklist(addr))
return true;
/* Check if the address is on a suffixed-symbol */
if (!lookup_symbol_name(addr, symname)) {
p = strchr(symname, '.');
if (!p)
return false;
*p = '\0';
addr = (unsigned long)kprobe_lookup_name(symname, 0);
if (addr)
return __within_kprobe_blacklist(addr);
}
return false;
}
/*
* If 'symbol_name' is specified, look it up and add the 'offset'
* 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(kprobe_opcode_t *addr,
const char *symbol_name, unsigned int offset)
{
if ((symbol_name && addr) || (!symbol_name && !addr))
goto invalid;
if (symbol_name) {
addr = kprobe_lookup_name(symbol_name, offset);
if (!addr)
return ERR_PTR(-ENOENT);
}
addr = (kprobe_opcode_t *)(((char *)addr) + offset);
if (addr)
return addr;
invalid:
return ERR_PTR(-EINVAL);
}
static kprobe_opcode_t *kprobe_addr(struct kprobe *p)
{
return _kprobe_addr(p->addr, p->symbol_name, p->offset);
}
/*
* Check the 'p' is valid and return the aggregator kprobe
* at the same address.
*/
static struct kprobe *__get_valid_kprobe(struct kprobe *p)
{
struct kprobe *ap, *list_p;
lockdep_assert_held(&kprobe_mutex);
ap = get_kprobe(p->addr);
if (unlikely(!ap))
return NULL;
if (p != ap) {
list_for_each_entry(list_p, &ap->list, list)
if (list_p == p)
/* kprobe p is a valid probe */
goto valid;
return NULL;
}
valid:
return ap;
}
/*
* Warn and return error if the kprobe is being re-registered since
* there must be a software bug.
*/
static inline int warn_kprobe_rereg(struct kprobe *p)
{
int ret = 0;
mutex_lock(&kprobe_mutex);
if (WARN_ON_ONCE(__get_valid_kprobe(p)))
ret = -EINVAL;
mutex_unlock(&kprobe_mutex);
return ret;
}
static int check_ftrace_location(struct kprobe *p)
{
unsigned long ftrace_addr;
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
}
return 0;
}
static int check_kprobe_address_safe(struct kprobe *p,
struct module **probed_mod)
{
int ret;
ret = check_ftrace_location(p);
if (ret)
return ret;
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) ||
static_call_text_reserved(p->addr, p->addr) ||
find_bug((unsigned long)p->addr)) {
ret = -EINVAL;
goto out;
}
/* Check if 'p' is 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 = warn_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;
}
cpus_read_lock();
/* Prevent text modification */
mutex_lock(&text_mutex);
ret = prepare_kprobe(p);
mutex_unlock(&text_mutex);
cpus_read_unlock();
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)) {
ret = arm_kprobe(p);
if (ret) {
hlist_del_rcu(&p->hlist);
synchronize_rcu();
goto out;
}
}
/* 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 'ap' are disabled. */
static bool aggr_kprobe_disabled(struct kprobe *ap)
{
struct kprobe *kp;
lockdep_assert_held(&kprobe_mutex);
list_for_each_entry(kp, &ap->list, list)
if (!kprobe_disabled(kp))
/*
* Since there is an active probe on the list,
* we can't disable this 'ap'.
*/
return false;
return true;
}
static struct kprobe *__disable_kprobe(struct kprobe *p)
{
struct kprobe *orig_p;
int ret;
lockdep_assert_held(&kprobe_mutex);
/* Get an original kprobe for return */
orig_p = __get_valid_kprobe(p);
if (unlikely(orig_p == NULL))
return ERR_PTR(-EINVAL);
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)) {
/*
* If 'kprobes_all_disarmed' is set, 'orig_p'
* should have already been disarmed, so
* skip unneed disarming process.
*/
if (!kprobes_all_disarmed) {
ret = disarm_kprobe(orig_p, true);
if (ret) {
p->flags &= ~KPROBE_FLAG_DISABLED;
return ERR_PTR(ret);
}
}
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 (IS_ERR(ap))
return PTR_ERR(ap);
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->post_handler && !kprobe_gone(p)) {
list_for_each_entry(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:
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_rcu();
for (i = 0; i < num; i++)
if (kps[i]->addr)
__unregister_kprobe_bottom(kps[i]);
}
EXPORT_SYMBOL_GPL(unregister_kprobes);
int __weak kprobe_exceptions_notify(struct notifier_block *self,
unsigned long val, void *data)
{
return NOTIFY_DONE;
}
NOKPROBE_SYMBOL(kprobe_exceptions_notify);
static struct notifier_block kprobe_exceptions_nb = {
.notifier_call = kprobe_exceptions_notify,
.priority = 0x7fffffff /* we need to be notified first */
};
#ifdef CONFIG_KRETPROBES
/* This assumes the 'tsk' is the current task or the is not running. */
static kprobe_opcode_t *__kretprobe_find_ret_addr(struct task_struct *tsk,
struct llist_node **cur)
{
struct kretprobe_instance *ri = NULL;
struct llist_node *node = *cur;
if (!node)
node = tsk->kretprobe_instances.first;
else
node = node->next;
while (node) {
ri = container_of(node, struct kretprobe_instance, llist);
if (ri->ret_addr != kretprobe_trampoline_addr()) {
*cur = node;
return ri->ret_addr;
}
node = node->next;
}
return NULL;
}
NOKPROBE_SYMBOL(__kretprobe_find_ret_addr);
/**
* kretprobe_find_ret_addr -- Find correct return address modified by kretprobe
* @tsk: Target task
* @fp: A frame pointer
* @cur: a storage of the loop cursor llist_node pointer for next call
*
* Find the correct return address modified by a kretprobe on @tsk in unsigned
* long type. If it finds the return address, this returns that address value,
* or this returns 0.
* The @tsk must be 'current' or a task which is not running. @fp is a hint
* to get the currect return address - which is compared with the
* kretprobe_instance::fp field. The @cur is a loop cursor for searching the
* kretprobe return addresses on the @tsk. The '*@cur' should be NULL at the
* first call, but '@cur' itself must NOT NULL.
*/
unsigned long kretprobe_find_ret_addr(struct task_struct *tsk, void *fp,
struct llist_node **cur)
{
struct kretprobe_instance *ri = NULL;
kprobe_opcode_t *ret;
if (WARN_ON_ONCE(!cur))
return 0;
do {
ret = __kretprobe_find_ret_addr(tsk, cur);
if (!ret)
break;
ri = container_of(*cur, struct kretprobe_instance, llist);
} while (ri->fp != fp);
return (unsigned long)ret;
}
NOKPROBE_SYMBOL(kretprobe_find_ret_addr);
void __weak arch_kretprobe_fixup_return(struct pt_regs *regs,
kprobe_opcode_t *correct_ret_addr)
{
/*
* Do nothing by default. Please fill this to update the fake return
* address on the stack with the correct one on each arch if possible.
*/
}
unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
void *frame_pointer)
{
kprobe_opcode_t *correct_ret_addr = NULL;
struct kretprobe_instance *ri = NULL;
struct llist_node *first, *node = NULL;
struct kretprobe *rp;
/* Find correct address and all nodes for this frame. */
correct_ret_addr = __kretprobe_find_ret_addr(current, &node);
if (!correct_ret_addr) {
pr_err("kretprobe: Return address not found, not execute handler. Maybe there is a bug in the kernel.\n");
BUG_ON(1);
}
/*
* Set the return address as the instruction pointer, because if the
* user handler calls stack_trace_save_regs() with this 'regs',
* the stack trace will start from the instruction pointer.
*/
instruction_pointer_set(regs, (unsigned long)correct_ret_addr);
/* Run the user handler of the nodes. */
first = current->kretprobe_instances.first;
while (first) {
ri = container_of(first, struct kretprobe_instance, llist);
if (WARN_ON_ONCE(ri->fp != frame_pointer))
break;
rp = get_kretprobe(ri);
if (rp && rp->handler) {
struct kprobe *prev = kprobe_running();
__this_cpu_write(current_kprobe, &rp->kp);
ri->ret_addr = correct_ret_addr;
rp->handler(ri, regs);
__this_cpu_write(current_kprobe, prev);
}
if (first == node)
break;
first = first->next;
}
arch_kretprobe_fixup_return(regs, correct_ret_addr);
/* Unlink all nodes for this frame. */
first = current->kretprobe_instances.first;
current->kretprobe_instances.first = node->next;
node->next = NULL;
/* Recycle free instances. */
while (first) {
ri = container_of(first, struct kretprobe_instance, llist);
first = first->next;
recycle_rp_inst(ri);
}
return (unsigned long)correct_ret_addr;
}
NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)
/*
* 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);
struct kretprobe_instance *ri;
struct freelist_node *fn;
fn = freelist_try_get(&rp->freelist);
if (!fn) {
rp->nmissed++;
return 0;
}
ri = container_of(fn, struct kretprobe_instance, freelist);
if (rp->entry_handler && rp->entry_handler(ri, regs)) {
freelist_add(&ri->freelist, &rp->freelist);
return 0;
}
arch_prepare_kretprobe(ri, regs);
__llist_add(&ri->llist, &current->kretprobe_instances);
return 0;
}
NOKPROBE_SYMBOL(pre_handler_kretprobe);
bool __weak arch_kprobe_on_func_entry(unsigned long offset)
{
return !offset;
}
/**
* kprobe_on_func_entry() -- check whether given address is function entry
* @addr: Target address
* @sym: Target symbol name
* @offset: The offset from the symbol or the address
*
* This checks whether the given @addr+@offset or @sym+@offset is on the
* function entry address or not.
* This returns 0 if it is the function entry, or -EINVAL if it is not.
* And also it returns -ENOENT if it fails the symbol or address lookup.
* Caller must pass @addr or @sym (either one must be NULL), or this
* returns -EINVAL.
*/
int kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset)
{
kprobe_opcode_t *kp_addr = _kprobe_addr(addr, sym, offset);
if (IS_ERR(kp_addr))
return PTR_ERR(kp_addr);
if (!kallsyms_lookup_size_offset((unsigned long)kp_addr, NULL, &offset))
return -ENOENT;
if (!arch_kprobe_on_func_entry(offset))
return -EINVAL;
return 0;
}
int register_kretprobe(struct kretprobe *rp)
{
int ret;
struct kretprobe_instance *inst;
int i;
void *addr;
ret = kprobe_on_func_entry(rp->kp.addr, rp->kp.symbol_name, rp->kp.offset);
if (ret)
return ret;
/* If only 'rp->kp.addr' is specified, check reregistering kprobes */
if (rp->kp.addr && warn_kprobe_rereg(&rp->kp))
return -EINVAL;
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;
/* Pre-allocate memory for max kretprobe instances */
if (rp->maxactive <= 0) {
#ifdef CONFIG_PREEMPTION
rp->maxactive = max_t(unsigned int, 10, 2*num_possible_cpus());
#else
rp->maxactive = num_possible_cpus();
#endif
}
rp->freelist.head = NULL;
rp->rph = kzalloc(sizeof(struct kretprobe_holder), GFP_KERNEL);
if (!rp->rph)
return -ENOMEM;
rp->rph->rp = rp;
for (i = 0; i < rp->maxactive; i++) {
inst = kzalloc(sizeof(struct kretprobe_instance) +
rp->data_size, GFP_KERNEL);
if (inst == NULL) {
refcount_set(&rp->rph->ref, i);
free_rp_inst(rp);
return -ENOMEM;
}
inst->rph = rp->rph;
freelist_add(&inst->freelist, &rp->freelist);
}
refcount_set(&rp->rph->ref, i);
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;
rps[i]->rph->rp = NULL;
}
mutex_unlock(&kprobe_mutex);
synchronize_rcu();
for (i = 0; i < num; i++) {
if (rps[i]->kp.addr) {
__unregister_kprobe_bottom(&rps[i]->kp);
free_rp_inst(rps[i]);
}
}
}
EXPORT_SYMBOL_GPL(unregister_kretprobes);
#else /* CONFIG_KRETPROBES */
int register_kretprobe(struct kretprobe *rp)
{
return -EOPNOTSUPP;
}
EXPORT_SYMBOL_GPL(register_kretprobe);
int register_kretprobes(struct kretprobe **rps, int num)
{
return -EOPNOTSUPP;
}
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;
lockdep_assert_held(&kprobe_mutex);
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(kp, &p->list, list)
kp->flags |= KPROBE_FLAG_GONE;
p->post_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);
/*
* The module is going away. We should disarm the kprobe which
* is using ftrace, because ftrace framework is still available at
* 'MODULE_STATE_GOING' notification.
*/
if (kprobe_ftrace(p) && !kprobe_disabled(p) && !kprobes_all_disarmed)
disarm_kprobe_ftrace(p);
}
/* Disable one kprobe */
int disable_kprobe(struct kprobe *kp)
{
int ret = 0;
struct kprobe *p;
mutex_lock(&kprobe_mutex);
/* Disable this kprobe */
p = __disable_kprobe(kp);
if (IS_ERR(p))
ret = PTR_ERR(p);
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;
ret = arm_kprobe(p);
if (ret)
p->flags |= KPROBE_FLAG_DISABLED;
}
out:
mutex_unlock(&kprobe_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(enable_kprobe);
/* Caller must NOT call this in usual path. This is only for critical case */
void dump_kprobe(struct kprobe *kp)
{
pr_err("Dump kprobe:\n.symbol_name = %s, .offset = %x, .addr = %pS\n",
kp->symbol_name, kp->offset, kp->addr);
}
NOKPROBE_SYMBOL(dump_kprobe);
int kprobe_add_ksym_blacklist(unsigned long entry)
{
struct kprobe_blacklist_entry *ent;
unsigned long offset = 0, size = 0;
if (!kernel_text_address(entry) ||
!kallsyms_lookup_size_offset(entry, &size, &offset))
return -EINVAL;
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 (int)size;
}
/* Add all symbols in given area into kprobe blacklist */
int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
{
unsigned long entry;
int ret = 0;
for (entry = start; entry < end; entry += ret) {
ret = kprobe_add_ksym_blacklist(entry);
if (ret < 0)
return ret;
if (ret == 0) /* In case of alias symbol */
ret = 1;
}
return 0;
}
/* Remove all symbols in given area from kprobe blacklist */
static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
{
struct kprobe_blacklist_entry *ent, *n;
list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) {
if (ent->start_addr < start || ent->start_addr >= end)
continue;
list_del(&ent->list);
kfree(ent);
}
}
static void kprobe_remove_ksym_blacklist(unsigned long entry)
{
kprobe_remove_area_blacklist(entry, entry + 1);
}
int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
char *type, char *sym)
{
return -ERANGE;
}
int kprobe_get_kallsym(unsigned int symnum, unsigned long *value, char *type,
char *sym)
{
#ifdef __ARCH_WANT_KPROBES_INSN_SLOT
if (!kprobe_cache_get_kallsym(&kprobe_insn_slots, &symnum, value, type, sym))
return 0;
#ifdef CONFIG_OPTPROBES
if (!kprobe_cache_get_kallsym(&kprobe_optinsn_slots, &symnum, value, type, sym))
return 0;
#endif
#endif
if (!arch_kprobe_get_kallsym(&symnum, value, type, sym))
return 0;
return -ERANGE;
}
int __init __weak arch_populate_kprobe_blacklist(void)
{
return 0;
}
/*
* 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 entry;
unsigned long *iter;
int ret;
for (iter = start; iter < end; iter++) {
entry = (unsigned long)dereference_symbol_descriptor((void *)*iter);
ret = kprobe_add_ksym_blacklist(entry);
if (ret == -EINVAL)
continue;
if (ret < 0)
return ret;
}
/* Symbols in '__kprobes_text' are blacklisted */
ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
(unsigned long)__kprobes_text_end);
if (ret)
return ret;
/* Symbols in 'noinstr' section are blacklisted */
ret = kprobe_add_area_blacklist((unsigned long)__noinstr_text_start,
(unsigned long)__noinstr_text_end);
return ret ? : arch_populate_kprobe_blacklist();
}
static void add_module_kprobe_blacklist(struct module *mod)
{
unsigned long start, end;
int i;
if (mod->kprobe_blacklist) {
for (i = 0; i < mod->num_kprobe_blacklist; i++)
kprobe_add_ksym_blacklist(mod->kprobe_blacklist[i]);
}
start = (unsigned long)mod->kprobes_text_start;
if (start) {
end = start + mod->kprobes_text_size;
kprobe_add_area_blacklist(start, end);
}
start = (unsigned long)mod->noinstr_text_start;
if (start) {
end = start + mod->noinstr_text_size;
kprobe_add_area_blacklist(start, end);
}
}
static void remove_module_kprobe_blacklist(struct module *mod)
{
unsigned long start, end;
int i;
if (mod->kprobe_blacklist) {
for (i = 0; i < mod->num_kprobe_blacklist; i++)
kprobe_remove_ksym_blacklist(mod->kprobe_blacklist[i]);
}
start = (unsigned long)mod->kprobes_text_start;
if (start) {
end = start + mod->kprobes_text_size;
kprobe_remove_area_blacklist(start, end);
}
start = (unsigned long)mod->noinstr_text_start;
if (start) {
end = start + mod->noinstr_text_size;
kprobe_remove_area_blacklist(start, end);
}
}
/* 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_COMING) {
mutex_lock(&kprobe_mutex);
add_module_kprobe_blacklist(mod);
mutex_unlock(&kprobe_mutex);
}
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(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.
*
* Note, this will also move any optimized probes
* that are pending to be removed from their
* corresponding lists to the 'freeing_list' and
* will not be touched by the delayed
* kprobe_optimizer() work handler.
*/
kill_kprobe(p);
}
}
if (val == MODULE_STATE_GOING)
remove_module_kprobe_blacklist(mod);
mutex_unlock(&kprobe_mutex);
return NOTIFY_DONE;
}
static struct notifier_block kprobe_module_nb = {
.notifier_call = kprobes_module_callback,
.priority = 0
};
void kprobe_free_init_mem(void)
{
void *start = (void *)(&__init_begin);
void *end = (void *)(&__init_end);
struct hlist_head *head;
struct kprobe *p;
int i;
mutex_lock(&kprobe_mutex);
/* Kill all kprobes on initmem because the target code has been freed. */
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
hlist_for_each_entry(p, head, hlist) {
if (start <= (void *)p->addr && (void *)p->addr < end)
kill_kprobe(p);
}
}
mutex_unlock(&kprobe_mutex);
}
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]);
err = populate_kprobe_blacklist(__start_kprobe_blacklist,
__stop_kprobe_blacklist);
if (err)
pr_err("Failed to populate blacklist (error %d), kprobes not restricted, be careful using them!\n", err);
if (kretprobe_blacklist_size) {
/* lookup the function address from its name */
for (i = 0; kretprobe_blacklist[i].name != NULL; i++) {
kretprobe_blacklist[i].addr =
kprobe_lookup_name(kretprobe_blacklist[i].name, 0);
if (!kretprobe_blacklist[i].addr)
pr_err("Failed to lookup symbol '%s' for kretprobe blacklist. Maybe the target function is removed or renamed.\n",
kretprobe_blacklist[i].name);
}
}
/* By default, kprobes are armed */
kprobes_all_disarmed = false;
#if defined(CONFIG_OPTPROBES) && defined(__ARCH_WANT_KPROBES_INSN_SLOT)
/* Init 'kprobe_optinsn_slots' for allocation */
kprobe_optinsn_slots.insn_size = MAX_OPTINSN_SIZE;
#endif
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);
return err;
}
early_initcall(init_kprobes);
#if defined(CONFIG_OPTPROBES)
static int __init init_optprobes(void)
{
/*
* Enable kprobe optimization - this kicks the optimizer which
* depends on synchronize_rcu_tasks() and ksoftirqd, that is
* not spawned in early initcall. So delay the optimization.
*/
optimize_all_kprobes();
return 0;
}
subsys_initcall(init_optprobes);
#endif
#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;
void *addr = p->addr;
if (p->pre_handler == pre_handler_kretprobe)
kprobe_type = "r";
else
kprobe_type = "k";
if (!kallsyms_show_value(pi->file->f_cred))
addr = NULL;
if (sym)
seq_printf(pi, "%px %s %s+0x%x %s ",
addr, kprobe_type, sym, offset,
(modname ? modname : " "));
else /* try to use %pS */
seq_printf(pi, "%px %s %pS ",
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_sops = {
.start = kprobe_seq_start,
.next = kprobe_seq_next,
.stop = kprobe_seq_stop,
.show = show_kprobe_addr
};
DEFINE_SEQ_ATTRIBUTE(kprobes);
/* kprobes/blacklist -- shows which functions can not be probed */
static void *kprobe_blacklist_seq_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&kprobe_mutex);
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);
/*
* If '/proc/kallsyms' is not showing kernel address, we won't
* show them here either.
*/
if (!kallsyms_show_value(m->file->f_cred))
seq_printf(m, "0x%px-0x%px\t%ps\n", NULL, NULL,
(void *)ent->start_addr);
else
seq_printf(m, "0x%px-0x%px\t%ps\n", (void *)ent->start_addr,
(void *)ent->end_addr, (void *)ent->start_addr);
return 0;
}
static void kprobe_blacklist_seq_stop(struct seq_file *f, void *v)
{
mutex_unlock(&kprobe_mutex);
}
static const struct seq_operations kprobe_blacklist_sops = {
.start = kprobe_blacklist_seq_start,
.next = kprobe_blacklist_seq_next,
.stop = kprobe_blacklist_seq_stop,
.show = kprobe_blacklist_seq_show,
};
DEFINE_SEQ_ATTRIBUTE(kprobe_blacklist);
static int arm_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i, total = 0, errors = 0;
int err, ret = 0;
mutex_lock(&kprobe_mutex);
/* If kprobes are armed, just return */
if (!kprobes_all_disarmed)
goto already_enabled;
/*
* optimize_kprobe() called by arm_kprobe() checks
* kprobes_all_disarmed, so set kprobes_all_disarmed before
* arm_kprobe.
*/
kprobes_all_disarmed = false;
/* Arming kprobes doesn't optimize kprobe itself */
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
/* Arm all kprobes on a best-effort basis */
hlist_for_each_entry(p, head, hlist) {
if (!kprobe_disabled(p)) {
err = arm_kprobe(p);
if (err) {
errors++;
ret = err;
}
total++;
}
}
}
if (errors)
pr_warn("Kprobes globally enabled, but failed to enable %d out of %d probes. Please check which kprobes are kept disabled via debugfs.\n",
errors, total);
else
pr_info("Kprobes globally enabled\n");
already_enabled:
mutex_unlock(&kprobe_mutex);
return ret;
}
static int disarm_all_kprobes(void)
{
struct hlist_head *head;
struct kprobe *p;
unsigned int i, total = 0, errors = 0;
int err, ret = 0;
mutex_lock(&kprobe_mutex);
/* If kprobes are already disarmed, just return */
if (kprobes_all_disarmed) {
mutex_unlock(&kprobe_mutex);
return 0;
}
kprobes_all_disarmed = true;
for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
head = &kprobe_table[i];
/* Disarm all kprobes on a best-effort basis */
hlist_for_each_entry(p, head, hlist) {
if (!arch_trampoline_kprobe(p) && !kprobe_disabled(p)) {
err = disarm_kprobe(p, false);
if (err) {
errors++;
ret = err;
}
total++;
}
}
}
if (errors)
pr_warn("Kprobes globally disabled, but failed to disable %d out of %d probes. Please check which kprobes are kept enabled via debugfs.\n",
errors, total);
else
pr_info("Kprobes globally disabled\n");
mutex_unlock(&kprobe_mutex);
/* Wait for disarming all kprobes by optimizer */
wait_for_kprobe_optimizer();
return ret;
}
/*
* 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)
{
bool enable;
int ret;
ret = kstrtobool_from_user(user_buf, count, &enable);
if (ret)
return ret;
ret = enable ? arm_all_kprobes() : disarm_all_kprobes();
if (ret)
return ret;
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;
dir = debugfs_create_dir("kprobes", NULL);
debugfs_create_file("list", 0400, dir, NULL, &kprobes_fops);
debugfs_create_file("enabled", 0600, dir, NULL, &fops_kp);
debugfs_create_file("blacklist", 0400, dir, NULL,
&kprobe_blacklist_fops);
return 0;
}
late_initcall(debugfs_kprobe_init);
#endif