linux-kernel - [RFC PATCH -tip 08/16] x86/kprobes: Recover breakpoint instruction if KGDB knows

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Date:	Mon, 02 Apr 2012 01:03:41 +0900
From:	Masami Hiramatsu <masami.hiramatsu@...il.com>
To:	linux-kernel@...r.kernel.org
Cc:	Huang Ying <ying.huang@...el.com>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
	Jason Wessel <jason.wessel@...driver.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: [RFC PATCH -tip 08/16] x86/kprobes: Recover breakpoint instruction if
 KGDB knows

Recover a breakpoint instruction which KGDB has put.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu@...il.com>
---
 arch/x86/kernel/kprobes.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index e213fc8..ddd21b8 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -49,6 +49,7 @@
 #include <linux/kdebug.h>
 #include <linux/kallsyms.h>
 #include <linux/ftrace.h>
+#include <linux/kgdb.h>
 
 #include <asm/cacheflush.h>
 #include <asm/desc.h>
@@ -252,6 +253,14 @@ unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long add
 {
 	unsigned long __addr;
 
+#ifdef CONFIG_KGDB
+	/* Recover if kgdb has put a breakpoint */
+	if (kgdb_get_saved_instr(addr, buf)) {
+		memcpy(buf + BREAK_INSTR_SIZE, (void *)addr + BREAK_INSTR_SIZE,
+			(MAX_INSN_SIZE - BREAK_INSTR_SIZE) * sizeof(kprobe_opcode_t));
+		return (unsigned long)buf;
+	}
+#endif
 	__addr = __recover_optprobed_insn(buf, addr);
 	if (__addr != addr)
 		return __addr;

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