linux-kernel - [tip:perf/kprobes] kprobes, x86: Call exception

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Message-ID: <tip-ecd50f714c421c759354632dd00f70c718c95b10@git.kernel.org>
Date:	Thu, 24 Apr 2014 03:59:20 -0700
From:	tip-bot for Masami Hiramatsu <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	rusty@...tcorp.com.au, seiji.aguchi@....com, jkosina@...e.cz,
	keescook@...omium.org, masami.hiramatsu.pt@...achi.com,
	rostedt@...dmis.org, akpm@...ux-foundation.org, tglx@...utronix.de,
	bp@...e.de
Subject: [tip:perf/kprobes] kprobes, x86:
  Call exception_enter after kprobes handled

Commit-ID:  ecd50f714c421c759354632dd00f70c718c95b10
Gitweb:     http://git.kernel.org/tip/ecd50f714c421c759354632dd00f70c718c95b10
Author:     Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
AuthorDate: Thu, 17 Apr 2014 17:17:40 +0900
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 24 Apr 2014 10:03:00 +0200

kprobes, x86: Call exception_enter after kprobes handled

Move exception_enter() call after kprobes handler
is done. Since the exception_enter() involves
many other functions (like printk), it can cause
recursive int3/break loop when kprobes probe such
functions.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Reviewed-by: Steven Rostedt <rostedt@...dmis.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Borislav Petkov <bp@...e.de>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Kees Cook <keescook@...omium.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Cc: Seiji Aguchi <seiji.aguchi@....com>
Link: http://lkml.kernel.org/r/20140417081740.26341.10894.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/traps.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index e5d4a70..ba9abe9 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -327,7 +327,6 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
 	if (poke_int3_handler(regs))
 		return;
 
-	prev_state = exception_enter();
 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
 	if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 				SIGTRAP) == NOTIFY_STOP)
@@ -338,6 +337,7 @@ dotraplinkage void __kprobes notrace do_int3(struct pt_regs *regs, long error_co
 	if (kprobe_int3_handler(regs))
 		return;
 #endif
+	prev_state = exception_enter();
 
 	if (notify_die(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP,
 			SIGTRAP) == NOTIFY_STOP)
@@ -415,8 +415,6 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 	unsigned long dr6;
 	int si_code;
 
-	prev_state = exception_enter();
-
 	get_debugreg(dr6, 6);
 
 	/* Filter out all the reserved bits which are preset to 1 */
@@ -449,6 +447,7 @@ dotraplinkage void __kprobes do_debug(struct pt_regs *regs, long error_code)
 	if (kprobe_debug_handler(regs))
 		goto exit;
 #endif
+	prev_state = exception_enter();
 
 	if (notify_die(DIE_DEBUG, "debug", regs, (long)&dr6, error_code,
 							SIGTRAP) == NOTIFY_STOP)
--
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