Messages in this thread | | | Date | Tue, 21 Feb 2006 20:55:15 -0700 | From | David Mosberger-Tang <> | Subject | Re: IA64 non-contiguous memory space bugs |
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I'm only following this superficially, but keep in mind that a vm-area MUST NEVER cross a hole.
--david
On 2/21/06, Chen, Kenneth W <kenneth.w.chen@intel.com> wrote: > David Gibson wrote on Tuesday, February 21, 2006 4:14 PM > > First bug (confirmed many months ago by Chris Wedgwood) - you can get > > weird effects if you attempt to mmap() something into one of the > > address space gaps. The ia64 outer wrapper for mmap2() tries to > > prevent it, but doesn't do a good enough job, it's still possible > > indirectly with shmat() and maybe mremap(). Basic trouble is that > > most of the checks applied by the generic code assume that everything > > between 0 and TASK_SIZE is valid. > > Ha ha ha. > > On ia64, the low level tlb fault handler (vhpt_miss and nested_dtlb_miss) > checks that all unused address bits (between REGION_NUMBER and PGDIR_SHIFT) > should be all zero. If they are not zero, it will fall into page fault > handler and in there, ia64 should just send SEGV instead of happily hand > over a page. Buggy buggy.... > > - Ken > > - > To unsubscribe from this list: send the line "unsubscribe linux-ia64" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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