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Subject[PATCH] SAMPLES: kprobe_example: make it more easy to use
From
From: Yong Zhang <yong.zhang0@gmail.com>
Subject: [PATCH] SAMPLES: kprobe_example: make it more easy to use

Add parameter 'func' and 'offset' to it, thus make it more easy
to kprobe certain offset/function.

Also print the next PC in post_handler(), thus we can ealily
tell if there is something is wrong when kprobe fails. This
is inspirited by a bug which explores an issue on POWERPC-32
when intruction is emulated: https://lkml.org/lkml/2011/6/24/53

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
---

Attach it too since webmail may mangle it.

samples/kprobes/kprobe_example.c | 31 ++++++++++++++++++++++---------
1 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index ebf5e0c..bbae5f4 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/samples/kprobes/kprobe_example.c
@@ -13,11 +13,18 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kprobes.h>
+#include <linux/limits.h>
+
+static char func_name[NAME_MAX] = "do_fork";
+module_param_string(func, func_name, NAME_MAX, S_IRUGO);
+MODULE_PARM_DESC(func, "Function to kprobe");
+
+static unsigned int offset;
+module_param(offset, uint, S_IRUGO);
+MODULE_PARM_DESC(offset, "Function offset to kprobe");

/* For each probe you need to allocate a kprobe structure */
-static struct kprobe kp = {
- .symbol_name = "do_fork",
-};
+static struct kprobe kp;

/* kprobe pre_handler: called just before the probed instruction is executed */
static int handler_pre(struct kprobe *p, struct pt_regs *regs)
@@ -47,16 +54,20 @@ static void handler_post(struct kprobe *p, struct
pt_regs *regs,
unsigned long flags)
{
#ifdef CONFIG_X86
- printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n",
- p->addr, regs->flags);
+ printk(KERN_INFO "post_handler: p->addr = 0x%p, ip = %lx,"
+ " flags = 0x%lx\n",
+ p->addr, regs->ip, regs->flags);
#endif
#ifdef CONFIG_PPC
- printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n",
- p->addr, regs->msr);
+ printk(KERN_INFO "post_handler: p->addr = 0x%p, nip = 0x%lx,"
+ " msr = 0x%lx\n",
+ p->addr, regs->nip, regs->msr);
+ dump_stack();
#endif
#ifdef CONFIG_MIPS
- printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n",
- p->addr, regs->cp0_status);
+ printk(KERN_INFO "post_handler: p->addr = 0x%p, epc = 0x%lx,"
+ " status = 0x%lx\n",
+ p->addr, regs->cp0_epc, regs->cp0_status);
#endif
}

@@ -76,6 +87,8 @@ static int handler_fault(struct kprobe *p, struct
pt_regs *regs, int trapnr)
static int __init kprobe_init(void)
{
int ret;
+ kp.symbol_name = func_name;
+ kp.offset = offset;
kp.pre_handler = handler_pre;
kp.post_handler = handler_post;
kp.fault_handler = handler_fault;
--
1.7.4.1From 461c174faa74f10d0f2df28247709bd67e6c9333 Mon Sep 17 00:00:00 2001
From: Yong Zhang <yong.zhang0@gmail.com>
Date: Mon, 4 Jul 2011 15:12:36 +0800
Subject: [PATCH] SAMPLES: kprobe_example: make it more easy to use

Add parameter 'func' and 'offset' to it, thus make it more easy
to kprobe certain offset/function.

Also print the next PC in post_handler(), thus we can ealily
tell if there is something is wrong when kprobe fails. This
is inspirited by a bug which explores an issue on POWERPC-32
when intruction is emulated: https://lkml.org/lkml/2011/6/24/53

Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
---
samples/kprobes/kprobe_example.c | 31 ++++++++++++++++++++++---------
1 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c
index ebf5e0c..bbae5f4 100644
--- a/samples/kprobes/kprobe_example.c
+++ b/samples/kprobes/kprobe_example.c
@@ -13,11 +13,18 @@
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kprobes.h>
+#include <linux/limits.h>
+
+static char func_name[NAME_MAX] = "do_fork";
+module_param_string(func, func_name, NAME_MAX, S_IRUGO);
+MODULE_PARM_DESC(func, "Function to kprobe");
+
+static unsigned int offset;
+module_param(offset, uint, S_IRUGO);
+MODULE_PARM_DESC(offset, "Function offset to kprobe");

/* For each probe you need to allocate a kprobe structure */
-static struct kprobe kp = {
- .symbol_name = "do_fork",
-};
+static struct kprobe kp;

/* kprobe pre_handler: called just before the probed instruction is executed */
static int handler_pre(struct kprobe *p, struct pt_regs *regs)
@@ -47,16 +54,20 @@ static void handler_post(struct kprobe *p, struct pt_regs *regs,
unsigned long flags)
{
#ifdef CONFIG_X86
- printk(KERN_INFO "post_handler: p->addr = 0x%p, flags = 0x%lx\n",
- p->addr, regs->flags);
+ printk(KERN_INFO "post_handler: p->addr = 0x%p, ip = %lx,"
+ " flags = 0x%lx\n",
+ p->addr, regs->ip, regs->flags);
#endif
#ifdef CONFIG_PPC
- printk(KERN_INFO "post_handler: p->addr = 0x%p, msr = 0x%lx\n",
- p->addr, regs->msr);
+ printk(KERN_INFO "post_handler: p->addr = 0x%p, nip = 0x%lx,"
+ " msr = 0x%lx\n",
+ p->addr, regs->nip, regs->msr);
+ dump_stack();
#endif
#ifdef CONFIG_MIPS
- printk(KERN_INFO "post_handler: p->addr = 0x%p, status = 0x%lx\n",
- p->addr, regs->cp0_status);
+ printk(KERN_INFO "post_handler: p->addr = 0x%p, epc = 0x%lx,"
+ " status = 0x%lx\n",
+ p->addr, regs->cp0_epc, regs->cp0_status);
#endif
}

@@ -76,6 +87,8 @@ static int handler_fault(struct kprobe *p, struct pt_regs *regs, int trapnr)
static int __init kprobe_init(void)
{
int ret;
+ kp.symbol_name = func_name;
+ kp.offset = offset;
kp.pre_handler = handler_pre;
kp.post_handler = handler_post;
kp.fault_handler = handler_fault;
--
1.7.4.1
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