[PATCH] x86: clean up stack overflow debug check

[Ingo Molnar]

* jia zhang <jia.zhang2008@xxxxxxxxx> wrote:

> stack_overflow_check() should consider the stack usage of pt_regs, 
> and thus it could warn us in advance. Additionally, it looks a bit 
> good that the warning time starts at INITIAL_JIFFIES.
> 
> Signed-off-by: jia zhang <jia.zhang2008@xxxxxxxxx>
> ---
> Assume at the moment rsp get close to the check point before 
> interrupt arrives. When interrupt really happens, thread_info will 
> be partly overrode.
> 
>  arch/x86/kernel/irq_64.c |    7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> --- a/arch/x86/kernel/irq_64.c
> +++ b/arch/x86/kernel/irq_64.c
> @@ -29,11 +29,12 @@
>  static inline void stack_overflow_check(struct pt_regs *regs)
>  {
>  	u64 curbase = (u64)task_stack_page(current);
> -	static unsigned long warned = -60*HZ;
> +	static unsigned long warned = INITIAL_JIFFIES - 60*HZ;
>  
>  	if (regs->sp >= curbase && regs->sp <= curbase + THREAD_SIZE &&
> -	    regs->sp <  curbase + sizeof(struct thread_info) + 128 &&
> -	    time_after(jiffies, warned + 60*HZ)) {
> +			regs->sp < curbase + sizeof(struct thread_info) +
> +			sizeof(struct pt_regs) + 128 &&
> +			time_after(jiffies, warned + 60*HZ)) {
>  		printk("do_IRQ: %s near stack overflow (cur:%Lx,sp:%lx)\n",
>  		       current->comm, curbase, regs->sp);
>  		show_stack(NULL,NULL);

applied to tip/x86/debug, thanks! I also applied the clean up patch 
below on top of your fix.

	Ingo

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