Re: [PATCH] kretprobe: kretprobe-booster against 2.6.16-rc1 for i386

[Masami Hiramatsu]

Sorry, also I forgot to remove a solo decrement routine.

Masami Hiramatsu wrote:
> @@ -310,18 +338,11 @@ int __kprobes trampoline_probe_handler(s
>  	}
> 
>  	BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
> -	regs->eip = orig_ret_address;
> 
> -	reset_current_kprobe();
>  	spin_unlock_irqrestore(&kretprobe_lock, flags);
>  	preempt_enable_no_resched();
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^  This must cause a trouble.

So, I must remove it (when boosting)
> -	preempt_enable_no_resched();

I attatch the fixed patch to this mail.

> 
> -	/*
> -	 * By returning a non-zero value, we are telling
> -	 * kprobe_handler() that we don't want the post_handler
> -	 * to run (and have re-enabled preemption)
> -	 */
> -        return 1;
> +	return (void*)orig_ret_address;
>  }
> 
>  /*

-- 
Masami HIRAMATSU
2nd Research Dept.
Hitachi, Ltd., Systems Development Laboratory
E-mail: hiramatu@xxxxxxxxxxxxxxxxx

Signed-off-by: Masami Hiramatsu <hiramatu@xxxxxxxxxxxxxxxxx>

 kprobes.c |   57 ++++++++++++++++++++++++++++++++++++---------------------
 1 files changed, 36 insertions(+), 21 deletions(-)
diff -Narup a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
--- a/arch/i386/kernel/kprobes.c	2006-01-24 19:07:26.000000000 +0900
+++ b/arch/i386/kernel/kprobes.c	2006-01-31 10:26:46.000000000 +0900
@@ -255,17 +255,45 @@ no_kprobe:
  * here. When a retprobed function returns, this probe is hit and
  * trampoline_probe_handler() runs, calling the kretprobe's handler.
  */
- void kretprobe_trampoline_holder(void)
+ void __kprobes kretprobe_trampoline_holder(void)
  {
- 	asm volatile (  ".global kretprobe_trampoline\n"
+	 asm volatile ( ".global kretprobe_trampoline\n"
  			"kretprobe_trampoline: \n"
- 			"nop\n");
- }
+			"	subl $8, %esp\n"
+			"	pushf\n"
+			"	subl $20, %esp\n"
+			"	pushl %eax\n"
+			"	pushl %ebp\n"
+			"	pushl %edi\n"
+			"	pushl %esi\n"
+			"	pushl %edx\n"
+			"	pushl %ecx\n"
+			"	pushl %ebx\n"
+			"	movl %esp, %eax\n"
+			"	pushl %eax\n"
+			"	addl $60, %eax\n"
+			"	movl %eax, 56(%esp)\n"
+			"	movl $trampoline_handler, %eax\n"
+			"	call *%eax\n"
+			"	addl $4, %esp\n"
+			"	movl %eax, 56(%esp)\n"
+			"	popl %ebx\n"
+			"	popl %ecx\n"
+			"	popl %edx\n"
+			"	popl %esi\n"
+			"	popl %edi\n"
+			"	popl %ebp\n"
+			"	popl %eax\n"
+			"	addl $20, %esp\n"
+			"	popf\n"
+			"	addl $4, %esp\n"
+			"	ret\n");
+}

 /*
- * Called when we hit the probe point at kretprobe_trampoline
+ * Called from kretprobe_trampoline
  */
-int __kprobes trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
+asmlinkage void *__kprobes trampoline_handler(struct pt_regs *regs)
 {
         struct kretprobe_instance *ri = NULL;
         struct hlist_head *head;
@@ -310,18 +338,10 @@ int __kprobes trampoline_probe_handler(s
 	}

 	BUG_ON(!orig_ret_address || (orig_ret_address == trampoline_address));
-	regs->eip = orig_ret_address;

-	reset_current_kprobe();
 	spin_unlock_irqrestore(&kretprobe_lock, flags);
-	preempt_enable_no_resched();

-	/*
-	 * By returning a non-zero value, we are telling
-	 * kprobe_handler() that we don't want the post_handler
-	 * to run (and have re-enabled preemption)
-	 */
-        return 1;
+	return (void*)orig_ret_address;
 }

 /*
@@ -552,12 +572,7 @@ int __kprobes longjmp_break_handler(stru
 	return 0;
 }

-static struct kprobe trampoline_p = {
-	.addr = (kprobe_opcode_t *) &kretprobe_trampoline,
-	.pre_handler = trampoline_probe_handler
-};
-
 int __init arch_init_kprobes(void)
 {
-	return register_kprobe(&trampoline_p);
+	return 0;
 }


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