linux-kernel - [RFC PATCH 5/5] x86: change range of stack overflow checking

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Message-ID: <20111107055315.7928.77663.stgit@ltc219.sdl.hitachi.co.jp>
Date:	Mon, 07 Nov 2011 14:53:16 +0900
From:	Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>
To:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Randy Dunlap <rdunlap@...otime.net>
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-doc@...r.kernel.org, yrl.pp-manager.tt@...achi.com,
	Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [RFC PATCH 5/5] x86: change range of stack overflow checking

The original stack overflow checking checks if a stack pointer is
less than or equal to (curbase + THREAD_SIZE) as the 2nd condition.
However, it is not necessary since the 3rd one checks if the pointer
is lower than available stack size. This patch removes the 2nd one.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@...achi.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
---

 arch/x86/kernel/irq_64.c |    1 -
 1 files changed, 0 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/irq_64.c b/arch/x86/kernel/irq_64.c
index f7baedd..d85b338 100644
--- a/arch/x86/kernel/irq_64.c
+++ b/arch/x86/kernel/irq_64.c
@@ -73,7 +73,6 @@ static inline void stack_overflow_check(struct pt_regs *regs)
 		panic("low stack detected by irq handler - check messages\n");
 #else
 	if (regs->sp >= curbase &&
-		regs->sp <= curbase + THREAD_SIZE &&
 		regs->sp <  curbase + sizeof(struct thread_info) +
 					sizeof(struct pt_regs) + 128) {
 		WARN_ONCE(1,

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