Commit 37fe6a42 authored by Mitsuo Hayasaka's avatar Mitsuo Hayasaka Committed by Ingo Molnar
Browse files

x86: Check stack overflow in detail 



Currently, only kernel stack is checked for the overflow, which
is not sufficient for systems that need a high reliability. To
enhance it, it is required to check the IRQ and exception
stacks, as well.

This patch checks all the stack types and will cause messages of
stacks in detail when free stack space drops below a certain
limit except user stack.

Signed-off-by: default avatarMitsuo 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/20111129060829.11076.51733.stgit@ltc219.sdl.hitachi.co.jp


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
parent 69682b62

arch/x86/Kconfig.debug

+5 −2
Original line number Diff line number Diff line
@@ -63,8 +63,11 @@ config DEBUG_STACKOVERFLOW 
	bool "Check for stack overflows"

	depends on DEBUG_KERNEL

	---help---

	  This option will cause messages to be printed if free stack space

	  drops below a certain limit.

	  Say Y here if you want to check the overflows of kernel, IRQ

	  and exception stacks. This option will cause messages of the

	  stacks in detail when free stack space drops below a certain

	  limit.

	  If in doubt, say "N".



config X86_PTDUMP

	bool "Export kernel pagetable layout to userspace via debugfs"

arch/x86/kernel/irq_64.c

+23 −6
Original line number Diff line number Diff line
@@ -36,18 +36,35 @@ EXPORT_PER_CPU_SYMBOL(irq_regs); 
static inline void stack_overflow_check(struct pt_regs *regs)

{

#ifdef CONFIG_DEBUG_STACKOVERFLOW

	struct orig_ist *oist;

	u64 irq_stack_top, irq_stack_bottom;

	u64 estack_top, estack_bottom;

	u64 curbase = (u64)task_stack_page(current);



	if (user_mode_vm(regs))

		return;



	WARN_ONCE(regs->sp >= curbase &&

	if (regs->sp >= curbase &&

	    regs->sp <= curbase + THREAD_SIZE &&

		  regs->sp <  curbase + sizeof(struct thread_info) +

					sizeof(struct pt_regs) + 128,

	    regs->sp >= curbase + sizeof(struct thread_info) +

				  sizeof(struct pt_regs) + 128)

		return;



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

	irq_stack_bottom = (u64)__get_cpu_var(irq_stack_ptr);

	if (regs->sp >= irq_stack_top && regs->sp <= irq_stack_bottom)

		return;



	oist = &__get_cpu_var(orig_ist);

	estack_top = (u64)oist->ist[0] - EXCEPTION_STKSZ;

	estack_bottom = (u64)oist->ist[N_EXCEPTION_STACKS - 1];

	if (regs->sp >= estack_top && regs->sp <= estack_bottom)

		return;



		  "do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",

			current->comm, curbase, regs->sp);

	WARN_ONCE(1, "do_IRQ(): %s has overflown the kernel stack (cur:%Lx,sp:%lx,irq stk top-bottom:%Lx-%Lx,exception stk top-bottom:%Lx-%Lx)\n",

		current->comm, curbase, regs->sp,

		irq_stack_top, irq_stack_bottom,

		estack_top, estack_bottom);

#endif

}

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