From 4961f10e2205d0ededa291e12ec634efc58aa93c Mon Sep 17 00:00:00 2001 From: Eric Sandeen Date: Mon, 26 Jun 2006 14:00:05 +0200 Subject: [PATCH] [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: Eric Sandeen Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- arch/x86_64/Kconfig.debug | 7 +++++++ arch/x86_64/kernel/irq.c | 28 +++++++++++++++++++++++++++- 2 files changed, 34 insertions(+), 1 deletion(-) diff --git a/arch/x86_64/Kconfig.debug b/arch/x86_64/Kconfig.debug index 0226f08be874..087a04868b25 100644 --- a/arch/x86_64/Kconfig.debug +++ b/arch/x86_64/Kconfig.debug @@ -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" diff --git a/arch/x86_64/kernel/irq.c b/arch/x86_64/kernel/irq.c index 207ecdc39822..59518d4d4358 100644 --- a/arch/x86_64/kernel/irq.c +++ b/arch/x86_64/kernel/irq.c @@ -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();