Messages in this thread | | | Date | Sat, 16 Feb 2008 15:04:44 +0100 | From | Heiko Carstens <> | Subject | Re: + futex-runtime-enable-pi-and-robust-functionality.patch added to -mm tree |
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On Sat, Feb 16, 2008 at 02:48:17PM +0100, Thomas Gleixner wrote: > On Sat, 16 Feb 2008, Heiko Carstens wrote: > > > > Well, NULL pointer dereferencing is supposed to fail, isn't it ? > > > > I wasn't sure that this is true for all architectures, but... > > It's an requirement for futex support.
To be more precise: dereferencing alone won't cause an exception for NULL pointers on s390. Only writes will do so. That is very architecture specific since we cannot unmap page 0, it contains per-cpu data -- like exception pointers and all such stuff that the cpu needs. Just in case there is any code that relies on the fact that also reads via a NULL pointer are supposed to failed.
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