Messages in this thread | | | Subject | Re: [PATCH] (3/3) stack overflow checking for x86 | From | "David C. Hansen" <> | Date | 31 Oct 2002 14:08:34 -0800 |
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On Thu, 2002-10-31 at 13:30, Dave Jones wrote: > On Thu, Oct 31, 2002 at 11:20:52AM -0800, David C. Hansen wrote: > > * stack checking (3/3) > > - use gcc's profiling features to check for stack overflows upon > > entry to functions. > > - Warn if the task goes over 4k. > > - Panic if the stack gets within 512 bytes of overflowing. > > - use kksymoops information, if available > > > > This won't apply cleanly without the irqstack patch, but the conflict is > > easy to resolve. It requires the thread_info cleanup. > > I'm wondering about interaction between this patch and the > already merged CONFIG_DEBUG_STACKOVERFLOW ?
The currently merged one is very, very simple, but relatively worthless. There are no guarantees about catching an overflow, especially if it happens in a long call chain _after_ do_IRQ with interrupts disabled. Ben's version checks on entrance to every function, making it _much_ more likely to be caught, even during an interrupt. But, the currently merged one doesn't have any strange compiler requirements, like adding the -p option.
The irq stack patch would make the current check pretty worthless because the check happens just after the switch to a fresh irqstack would have happened.
But, if they both get in, it can be cleaned up later because even if both are turned on, nothing will blow up. -- Dave Hansen haveblue@us.ibm.com
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