kprobe not working for some functions

问题

I am trying to use kprobe to track handle_pte_fault function calls in linux kernel. I can probe handle_mm_fault but when I try to probe handle_pte_dault, kprobe's handler for handle_pte_fault doesn't print anything.

Using this I figured that i can't probe a function which is inline and also maybe static. So, I changed the definition of the handle_pte_fault function as following and recompiled the kernel.

From:

static int handle_pte_fault(struct vm_fault *vmf)

to:

noinline int handle_pte_fault(struct vm_fault *vmf)

I also added following to make sure handle_pte_fault symbol exists

EXPORT_SYMBOL_GPL(handle_pte_fault);

Still I am not able to track/probe handle_pte_fault function. Any help or explanation. Does it mean kprobe will only work for some random functions?

I am using kernel v4.13.

Below is the kernel module code for the kprobe that i am using:

#include<linux/module.h>
#include<linux/version.h>
#include<linux/kernel.h>
#include<linux/init.h>
#include<linux/kprobes.h>

static struct kprobe kp;
static const char *probed_func = "handle_pte_fault";

static unsigned int counter = 0;

int Pre_Handler(struct kprobe *p, struct pt_regs *regs){
        printk("Pre_Handler: counter=%u\n",counter++);
        return 0;
}

void Post_Handler(struct kprobe *p, struct pt_regs *regs, unsigned long flags){
        printk("Post_Handler: counter=%u\n",counter++);
}


int myinit(void)
{
        printk("module inserted\n ");

        kp.pre_handler = Pre_Handler;
        kp.post_handler = Post_Handler;
        kp.addr = (kprobe_opcode_t *)kallsyms_lookup_name(probed_func);

        register_kprobe(&kp);

        return 0;
}

void myexit(void)
{
        unregister_kprobe(&kp);
        printk("module removed\n ");
}

module_init(myinit);
module_exit(myexit);
MODULE_AUTHOR("User1");
MODULE_DESCRIPTION("KPROBE MODULE");
MODULE_LICENSE("GPL");

来源：https://stackoverflow.com/questions/49480167/kprobe-not-working-for-some-functions

标签

Linux

linux-kernel

kernel

kprobe

jprobe