Messages in this thread | | | Date | Mon, 15 May 2006 16:19:08 +0200 | From | Bart Hartgers <> | Subject | Re: Segfault on the i386 enter instruction |
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linux-os (Dick Johnson) wrote: > On Mon, 15 May 2006, Bart Hartgers wrote: > >> Tomasz Malesinski wrote: >>> On Fri, May 12, 2006 at 03:50:20PM +0200, Andi Kleen wrote: >>>> Handling it like you expect would require to disassemble >>>> the function in the page fault handler and it's probably not >>>> worth doing that for this weird case. >>> Does it mean that the ENTER instruction should not be used to create >>> stack frames in Linux programs? >>> >> Basically, yes. Here is a link to a relevant discussion in the 2.2.7 era: >> >> http://groups.google.co.nz/groups?selm=7i86ni%24b7n%241%40palladium.transmeta.com >> >> And perhaps x86-64 is handled different because of the red zone (some >> memory below the stack-pointer that can be accessed legally)? >> >> Groeten, >> Bart > > The enter instruction works perfectly fine. The processors were > designed to use both enter and leave. There are no prohibitions > against their use. It's just that if you play games with assembly > so you create a stack-pointer wrap situation, you can get a > bounds error.
No. The assembly is fine. Also enter does what it is supposed to do. The problem is that enter can cause a pagefault on an address (far) below the %esp, and Linu[xs] considers that an error (for good reasons).
Groeten, Bart -- Bart Hartgers - TUE Eindhoven - http://plasimo.phys.tue.nl/bart/contact/ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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