RE: [RFC] Kprobes for book-e

Kumar Gala wrote on Thursday, June 19, 2008 10:15 PM

To: Sulibhavi, Madhvesh

quoted

No!!, this code cannot be removed. My tests fail
while doing the probe test for do_gettimeofday and __kmalloc.
I get Oops and Segfault. I think i had got similar results
in my initial port using 2.6.26.39. Here is the log...

=20
What is that test.  Can you send it to me.  Its not clear to me why =20
this is an issue.

My test code is very simple and it is added at the
end of this mail. Brief steps include..

1. Build k-007.c and k-008.c as kernel modules
2. Insert the k-008.ko first=20
3. Insert k-007.ko
4. Do any operation like "ls"
5. Ooops will be seen followed by Segv


-Madhvesh

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//k-008.c test code

#include <linux/module.h>
#include <linux/init.h>
#include <linux/kprobes.h>
#include <linux/kallsyms.h>
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static struct kprobe k_008_kp1;
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static void __exit k_008_exit_probe(void)
{
        unregister_kprobe(&k_008_kp1);
}
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static int k_008_pre_handler(struct kprobe *k_008_kp1, struct pt_regs
*p)
{
        return 0;
}
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static int __init k_008_init_probe(void)
{

        /* Registering a kprobe */
        k_008_kp1.pre_handler =3D (kprobe_pre_handler_t)
k_008_pre_handler;
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        k_008_kp1.symbol_name =3D "do_gettimeofday";
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        if( register_kprobe(&k_008_kp1) <0 ) {
                printk("k-008.c: register_kprobe is failed\n");
                return -1;
        }
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        register_kprobe(&k_008_kp1);
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        return 0;
}
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module_init(k_008_init_probe);
module_exit(k_008_exit_probe);
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MODULE_DESCRIPTION("Kprobes test module");
MODULE_LICENSE("GPL");

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//k-007.c test code

static struct kprobe k_007_kp, k_007_kp1;
int k_007_kmalloc_count =3D 0;
int k_007_kfree_count =3D 0;
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static int k_007_kmalloc_hndlr(struct kprobe *kpr, struct pt_regs *p)
{
        k_007_kmalloc_count++;
        return 0;
}
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static int k_007_kfree_hndlr(struct kprobe *kpr, struct pt_regs *p)
{
        k_007_kfree_count++;
        return 0;
}
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static int __init k_007_kmf_init(void)
{
        k_007_kp.pre_handler =3D k_007_kmalloc_hndlr;
        k_007_kp1.pre_handler =3D k_007_kfree_hndlr;
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        k_007_kp.symbol_name =3D "__kmalloc";
        k_007_kp1.symbol_name =3D "kfree";
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        if( (register_kprobe(&k_007_kp) <0) ||
(register_kprobe(&k_007_kp1) <0) ) {
                printk("k-007.c: register_kprobe is failed\n");
                return -1;
        }
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        return 0;
}
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static void __exit k_007_kmf_exit(void)
{
        printk("%%%%%%%%%%%%%%%%%%%%%%%%%\n\n");
        printk("kmalloc count is %d \n", k_007_kmalloc_count);
        printk("kfree count is %d \n", k_007_kfree_count);
        printk("\n\n\n%%%%%%%%%%%%%%%%%%%%%%\n");
        unregister_kprobe(&k_007_kp);
        unregister_kprobe(&k_007_kp1);
        printk(KERN_INFO "k-007 exiting...\n");
}
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module_init(k_007_kmf_init);
module_exit(k_007_kmf_exit);
MODULE_LICENSE("GPL");
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