Commit 467e6b7a authored Nov 29, 2011 by Mitsuo Hayasaka Committed by Ingo Molnar Dec 05, 2011

x86: Clean up the range of stack overflow checking



The overflow checking of kernel stack checks if the stack
pointer points to the available kernel stack range, which is
derived from the original overflow checking.

It is clear that curbase address is always less than low
boundary of available kernel stack. So, this patch removes the
first condition that checks if the pointer is higher than
curbase.

Signed-off-by: Mitsuo Hayasaka <mitsuo.hayasaka.hu@hitachi.com>
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Randy Dunlap <rdunlap@xenotime.net>
Link: http://lkml.kernel.org/r/20111129060845.11076.40916.stgit@ltc219.sdl.hitachi.co.jp


Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>

parent 55af7796

arch/x86/kernel/irq_64.c

+3 −4

Original line number	Diff line number	Diff line
		@@ -46,10 +46,9 @@ static inline void stack_overflow_check(struct pt_regs *regs)
		if (user_mode_vm(regs))
		return;

		if (regs->sp >= curbase &&
		regs->sp <= curbase + THREAD_SIZE &&
		regs->sp >= curbase + sizeof(struct thread_info) +
		sizeof(struct pt_regs) + 128)
		if (regs->sp >= curbase + sizeof(struct thread_info) +
		sizeof(struct pt_regs) + 128 &&
		regs->sp <= curbase + THREAD_SIZE)
		return;

		irq_stack_top = (u64)__get_cpu_var(irq_stack_union.irq_stack);

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