Subject: Re: [PATCH] powerpc: Check end of stack canary at oops time

From: Anton Blanchard <[email-masked]>
Date: Wed, 25 Aug 2010 11:51:12 +1000

Hi,

> The check for init is just because we haven't set the magic value for
> init's stack right? But we could.

Yeah, it's similar to what x86 are doing now:

commit 0e7810be30f66e9f430c4ce2cd3b14634211690f
Author: Jan Beulich <[email-masked]>
Date:   Fri Nov 20 14:00:14 2009 +0000

    x86: Suppress stack overrun message for init_task
    
    init_task doesn't get its stack end location set to
    STACK_END_MAGIC, and hence the message is confusing
    rather than helpful in this case.

Adding it directly to init_task would be nice but I suspect we'd
either have to make assumptions about end_of_stack in our code or move the
canary into the thread_info (so we can statically allocate it via
INIT_THREAD_INFO()) or do it at runtime somewhere, hopefully early enough that
we couldn't take an oops.

Anton