From 1c56018e77a5b3e13c3948a74a7442d1032a6ec8 Mon Sep 17 00:00:00 2001 From: Yong Zhang 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 --- samples/kprobes/kprobe_example.c | 37 +++++++++++++++++++++++++------------ 1 files changed, 25 insertions(+), 12 deletions(-) diff --git a/samples/kprobes/kprobe_example.c b/samples/kprobes/kprobe_example.c index ebf5e0c..8394e98 100644 --- a/samples/kprobes/kprobe_example.c +++ b/samples/kprobes/kprobe_example.c @@ -13,11 +13,18 @@ #include #include #include +#include + +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) @@ -25,17 +32,17 @@ static int handler_pre(struct kprobe *p, struct pt_regs *regs) #ifdef CONFIG_X86 printk(KERN_INFO "pre_handler: p->addr = 0x%p, ip = %lx," " flags = 0x%lx\n", - p->addr, regs->ip, regs->flags); + p->addr, instruction_pointer(regs), regs->flags); #endif #ifdef CONFIG_PPC printk(KERN_INFO "pre_handler: p->addr = 0x%p, nip = 0x%lx," " msr = 0x%lx\n", - p->addr, regs->nip, regs->msr); + p->addr, instruction_pointer(regs), regs->msr); #endif #ifdef CONFIG_MIPS printk(KERN_INFO "pre_handler: p->addr = 0x%p, epc = 0x%lx," " status = 0x%lx\n", - p->addr, regs->cp0_epc, regs->cp0_status); + p->addr, instruction_pointer(regs), regs->cp0_status); #endif /* A dump_stack() here will give a stack backtrace */ @@ -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, instruction_pointer(regs), 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, instruction_pointer(regs), 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, instruction_pointer(regs), 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