Commit 4961f10e authored by Eric Sandeen's avatar Eric Sandeen Committed by Linus Torvalds
Browse files

[PATCH] x86_64: (resend) x86_64 stack overflow debugging 



Take two, now without spurious whitespace :(  Applies to git & 2.6.17-rc6

CONFIG_DEBUG_STACKOVERFLOW existed for x86_64 in 2.4, but seems to have gone AWOL in 2.6.

I've pretty much just copied this over from the 2.4 code, with
appropriate tweaks for the 2.6 kernel, plus a bugfix.  I'd personally
rather see it printed out the way other arches do it, i.e.
bytes-remaining-until-overflow, rather than having to do the subtraction
yourself.  Also, only 128 bytes remaining seems awfully late to issue a
warning.  But I'll start here :)

Signed-off-by: default avatarEric Sandeen <sandeen@sgi.com>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a4cffb64

arch/x86_64/Kconfig.debug

+7 −0
Original line number Diff line number Diff line
@@ -35,6 +35,13 @@ config IOMMU_LEAK 
         Add a simple leak tracer to the IOMMU code. This is useful when you

	 are debugging a buggy device driver that leaks IOMMU mappings.



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.



#config X86_REMOTE_DEBUG

#       bool "kgdb debugging stub"

arch/x86_64/kernel/irq.c

+27 −1
Original line number Diff line number Diff line
@@ -26,6 +26,30 @@ atomic_t irq_mis_count; 
#endif

#endif



#ifdef CONFIG_DEBUG_STACKOVERFLOW

/*

 * Probabilistic stack overflow check:

 *

 * Only check the stack in process context, because everything else

 * runs on the big interrupt stacks. Checking reliably is too expensive,

 * so we just check from interrupts.

 */

static inline void stack_overflow_check(struct pt_regs *regs)

{

	u64 curbase = (u64) current->thread_info;

	static unsigned long warned = -60*HZ;



	if (regs->rsp >= curbase && regs->rsp <= curbase + THREAD_SIZE &&

	    regs->rsp <  curbase + sizeof(struct thread_info) + 128 &&

	    time_after(jiffies, warned + 60*HZ)) {

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

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

		show_stack(NULL,NULL);

		warned = jiffies;

	}

}

#endif



/*

 * Generic, controller-independent functions:

 */
@@ -96,7 +120,9 @@ asmlinkage unsigned int do_IRQ(struct pt_regs *regs) 


	exit_idle();

	irq_enter();



#ifdef CONFIG_DEBUG_STACKOVERFLOW

	stack_overflow_check(regs);

#endif

	__do_IRQ(irq, regs);

	irq_exit();

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