linux-kernel - [PATCH 3/3] x86: WARN_ON breakpoints from .kprobes.text section

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Message-ID: <479C4A4F.10604@gmail.com>
Date:	Sun, 27 Jan 2008 14:39:35 +0530
From:	Abhishek Sagar <sagar.abhishek@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>
CC:	jkenisto@...ibm.com, ananth@...ibm.com,
	Masami Hiramatsu <mhiramat@...hat.com>,
	Ingo Molnar <mingo@...e.hu>
Subject: [PATCH 3/3] x86: WARN_ON breakpoints from .kprobes.text section

Identify breakpoints in .kprobes.text section. These certainly aren't kprobe traps. However, we make an exception for the breakpoint hardcoded into jprobe_return.

Signed-off-by: Abhishek Sagar <sagar.abhishek@...il.com>
---

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 45f2949..f3d13d0 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -961,6 +961,7 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 				       unsigned long val, void *data)
 {
 	struct die_args *args = data;
+	unsigned long addr = kprobe_bkpt_addr(args->regs);
 	int ret = NOTIFY_DONE;
 
 	if (args->regs && user_mode_vm(args->regs))
@@ -968,7 +969,14 @@ int __kprobes kprobe_exceptions_notify(struct notifier_block *self,
 
 	switch (val) {
 	case DIE_INT3:
-		if (kprobe_handler(args->regs))
+		if (in_kprobes_functions(addr) &&
+		    !is_jprobe_bkpt((u8 *)addr)) {
+			/* A breakpoint has made it's way to the .kprobes.text
+			 * section (excluding jprobe_return). This could be
+			 * due to an external debugger. */
+			WARN_ON(1);
+			
+		} else if (kprobe_handler(args->regs))
 			ret = NOTIFY_STOP;
 		break;
 	case DIE_DEBUG:
--
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