Commit 8c1c9356 authored by Ananth N Mavinakayanahalli's avatar Ananth N Mavinakayanahalli Committed by Ingo Molnar

x86: kprobes: add kprobes smoke tests that run on boot

Here is a quick and naive smoke test for kprobes. This is intended to
just verify if some unrelated change broke the *probes subsystem. It is
self contained, architecture agnostic and isn't of any great use by itself.

This needs to be built in the kernel and runs a basic set of tests to
verify if kprobes, jprobes and kretprobes run fine on the kernel. In case
of an error, it'll print out a message with a "BUG" prefix.

This is a start; we intend to add more tests to this bucket over time.

Thanks to Jim Keniston and Masami Hiramatsu for comments and suggestions.

Tested on x86 (32/64) and powerpc.
Signed-off-by: default avatarAnanth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 3334052a
...@@ -182,6 +182,15 @@ static inline void kretprobe_assert(struct kretprobe_instance *ri, ...@@ -182,6 +182,15 @@ static inline void kretprobe_assert(struct kretprobe_instance *ri,
} }
} }
#ifdef CONFIG_KPROBES_SANITY_TEST
extern int init_test_probes(void);
#else
static inline int init_test_probes(void)
{
return 0;
}
#endif /* CONFIG_KPROBES_SANITY_TEST */
extern spinlock_t kretprobe_lock; extern spinlock_t kretprobe_lock;
extern struct mutex kprobe_mutex; extern struct mutex kprobe_mutex;
extern int arch_prepare_kprobe(struct kprobe *p); extern int arch_prepare_kprobe(struct kprobe *p);
...@@ -227,6 +236,7 @@ void unregister_kretprobe(struct kretprobe *rp); ...@@ -227,6 +236,7 @@ void unregister_kretprobe(struct kretprobe *rp);
void kprobe_flush_task(struct task_struct *tk); void kprobe_flush_task(struct task_struct *tk);
void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head); void recycle_rp_inst(struct kretprobe_instance *ri, struct hlist_head *head);
#else /* CONFIG_KPROBES */ #else /* CONFIG_KPROBES */
#define __kprobes /**/ #define __kprobes /**/
......
...@@ -43,6 +43,7 @@ obj-$(CONFIG_CPUSETS) += cpuset.o ...@@ -43,6 +43,7 @@ obj-$(CONFIG_CPUSETS) += cpuset.o
obj-$(CONFIG_CGROUP_NS) += ns_cgroup.o obj-$(CONFIG_CGROUP_NS) += ns_cgroup.o
obj-$(CONFIG_IKCONFIG) += configs.o obj-$(CONFIG_IKCONFIG) += configs.o
obj-$(CONFIG_STOP_MACHINE) += stop_machine.o obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
obj-$(CONFIG_AUDIT) += audit.o auditfilter.o obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
obj-$(CONFIG_AUDITSYSCALL) += auditsc.o obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
obj-$(CONFIG_AUDIT_TREE) += audit_tree.o obj-$(CONFIG_AUDIT_TREE) += audit_tree.o
......
...@@ -824,6 +824,8 @@ static int __init init_kprobes(void) ...@@ -824,6 +824,8 @@ static int __init init_kprobes(void)
if (!err) if (!err)
err = register_die_notifier(&kprobe_exceptions_nb); err = register_die_notifier(&kprobe_exceptions_nb);
if (!err)
init_test_probes();
return err; return err;
} }
......
/*
* test_kprobes.c - simple sanity test for *probes
*
* Copyright IBM Corp. 2008
*
* 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 would 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.
*/
#include <linux/kernel.h>
#include <linux/kprobes.h>
#include <linux/random.h>
#define div_factor 3
static u32 rand1, preh_val, posth_val, jph_val;
static int errors, handler_errors, num_tests;
static noinline u32 kprobe_target(u32 value)
{
/*
* gcc ignores noinline on some architectures unless we stuff
* sufficient lard into the function. The get_kprobe() here is
* just for that.
*
* NOTE: We aren't concerned about the correctness of get_kprobe()
* here; hence, this call is neither under !preempt nor with the
* kprobe_mutex held. This is fine(tm)
*/
if (get_kprobe((void *)0xdeadbeef))
printk(KERN_INFO "Kprobe smoke test: probe on 0xdeadbeef!\n");
return (value / div_factor);
}
static int kp_pre_handler(struct kprobe *p, struct pt_regs *regs)
{
preh_val = (rand1 / div_factor);
return 0;
}
static void kp_post_handler(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
if (preh_val != (rand1 / div_factor)) {
handler_errors++;
printk(KERN_ERR "Kprobe smoke test failed: "
"incorrect value in post_handler\n");
}
posth_val = preh_val + div_factor;
}
static struct kprobe kp = {
.symbol_name = "kprobe_target",
.pre_handler = kp_pre_handler,
.post_handler = kp_post_handler
};
static int test_kprobe(void)
{
int ret;
ret = register_kprobe(&kp);
if (ret < 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"register_kprobe returned %d\n", ret);
return ret;
}
ret = kprobe_target(rand1);
unregister_kprobe(&kp);
if (preh_val == 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"kprobe pre_handler not called\n");
handler_errors++;
}
if (posth_val == 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"kprobe post_handler not called\n");
handler_errors++;
}
return 0;
}
static u32 j_kprobe_target(u32 value)
{
if (value != rand1) {
handler_errors++;
printk(KERN_ERR "Kprobe smoke test failed: "
"incorrect value in jprobe handler\n");
}
jph_val = rand1;
jprobe_return();
return 0;
}
static struct jprobe jp = {
.entry = j_kprobe_target,
.kp.symbol_name = "kprobe_target"
};
static int test_jprobe(void)
{
int ret;
ret = register_jprobe(&jp);
if (ret < 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"register_jprobe returned %d\n", ret);
return ret;
}
ret = kprobe_target(rand1);
unregister_jprobe(&jp);
if (jph_val == 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"jprobe handler not called\n");
handler_errors++;
}
return 0;
}
#ifdef CONFIG_KRETPROBES
static u32 krph_val;
static int return_handler(struct kretprobe_instance *ri, struct pt_regs *regs)
{
unsigned long ret = regs_return_value(regs);
if (ret != (rand1 / div_factor)) {
handler_errors++;
printk(KERN_ERR "Kprobe smoke test failed: "
"incorrect value in kretprobe handler\n");
}
krph_val = (rand1 / div_factor);
return 0;
}
static struct kretprobe rp = {
.handler = return_handler,
.kp.symbol_name = "kprobe_target"
};
static int test_kretprobe(void)
{
int ret;
ret = register_kretprobe(&rp);
if (ret < 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"register_kretprobe returned %d\n", ret);
return ret;
}
ret = kprobe_target(rand1);
unregister_kretprobe(&rp);
if (krph_val == 0) {
printk(KERN_ERR "Kprobe smoke test failed: "
"kretprobe handler not called\n");
handler_errors++;
}
return 0;
}
#endif /* CONFIG_KRETPROBES */
int init_test_probes(void)
{
int ret;
do {
rand1 = random32();
} while (rand1 <= div_factor);
printk(KERN_INFO "Kprobe smoke test started\n");
num_tests++;
ret = test_kprobe();
if (ret < 0)
errors++;
num_tests++;
ret = test_jprobe();
if (ret < 0)
errors++;
#ifdef CONFIG_KRETPROBES
num_tests++;
ret = test_kretprobe();
if (ret < 0)
errors++;
#endif /* CONFIG_KRETPROBES */
if (errors)
printk(KERN_ERR "BUG: Kprobe smoke test: %d out of "
"%d tests failed\n", errors, num_tests);
else if (handler_errors)
printk(KERN_ERR "BUG: Kprobe smoke test: %d error(s) "
"running handlers\n", handler_errors);
else
printk(KERN_INFO "Kprobe smoke test passed successfully\n");
return 0;
}
...@@ -494,6 +494,18 @@ config RCU_TORTURE_TEST ...@@ -494,6 +494,18 @@ config RCU_TORTURE_TEST
Say M if you want the RCU torture tests to build as a module. Say M if you want the RCU torture tests to build as a module.
Say N if you are unsure. Say N if you are unsure.
config KPROBES_SANITY_TEST
bool "Kprobes sanity tests"
depends on DEBUG_KERNEL
depends on KPROBES
default n
help
This option provides for testing basic kprobes functionality on
boot. A sample kprobe, jprobe and kretprobe are inserted and
verified for functionality.
Say N if you are unsure.
config LKDTM config LKDTM
tristate "Linux Kernel Dump Test Tool Module" tristate "Linux Kernel Dump Test Tool Module"
depends on DEBUG_KERNEL depends on DEBUG_KERNEL
......
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