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* [PATCH] SAMPLES: kprobe_example: make it more easy to use
@ 2011-07-04  7:27 Yong Zhang
  2011-07-04 10:14 ` Ananth N Mavinakayanahalli
  0 siblings, 1 reply; 4+ messages in thread
From: Yong Zhang @ 2011-07-04  7:27 UTC (permalink / raw)
  To: linux-kernel; +Cc: ananth

[-- Attachment #1: Type: text/plain, Size: 2761 bytes --]

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;
-- 
1.7.4.1

[-- Attachment #2: 0001-SAMPLES-kprobe_example-make-it-more-easy-to-use.patch --]
[-- Type: text/x-patch, Size: 2828 bytes --]

From 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


^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2011-07-05  4:52 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-07-04  7:27 [PATCH] SAMPLES: kprobe_example: make it more easy to use Yong Zhang
2011-07-04 10:14 ` Ananth N Mavinakayanahalli
2011-07-05  2:00   ` Yong Zhang
2011-07-05  4:44     ` Ananth N Mavinakayanahalli

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