Re: Incorrect alignment assumptions in x86_64 stacktrace

From: Keith Owens
Date: Fri Aug 25 2006 - 03:40:43 EST


Andi Kleen (on Fri, 25 Aug 2006 09:33:53 +0200) wrote:
>On Friday 25 August 2006 08:59, Keith Owens wrote:
>> 2.6.18-rc4 arch/x86_64/kernel/stacktrace.c::get_stack_end() incorrectly
>> assumes that the irqstackptr is IRQSTACKSIZE aligned.
>>
>> stack_end = (unsigned long)cpu_pda(cpu)->irqstackptr;
>> if (stack_end) {
>> stack_start = stack_end & ~(IRQSTACKSIZE-1);
>>
>> irqstackptr is only guaranteed to be page aligned, not IRQSTACKSIZE
>> (4*PAGE_SIZE) aligned.
>
>Thanks. I have already removed that code post 2.6.18 (the standard backtracer
>now does both stacktrace and show_trace)
>
>You think it is important enough for 2.6.18?

Depends if any x86_64 distributions are going to be based on 2.6.18. I
hear rumours, but no facts.

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