Messages in this thread | | | Subject | Re: Really good idea to allow mmap(0, FIXED)? | From | Arjan van de Ven <> | Date | Fri, 06 Oct 2006 13:20:05 +0200 |
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On Fri, 2006-10-06 at 12:36 +0200, Mikael Pettersson wrote: > Arjan van de Ven writes: > > > mmap(0, 4096, PROT_READ|PROT_EXEC|PROT_WRITE, > > > MAP_FIXED|MAP_PRIVATE|MAP_ANONYMOUS, 0, 0); > > > struct s *bar = 0; > > > > the question isn't if it's a good idea to allow mmap(0) but to allow > > mmap PROT_WRITE | PROT_EXEC ! > > It is if you want JITs, code loaders, virtualisation engines, etc > to continue working.
yeah I know we can't forbid it point blank (having said that, on architectures where I and D cache aren't coherent (and there are many, including ia64), most of these are buggy anyway; the sane ones actually do an mprotect between writing and executing, so that the kernel can take care of the cache coherency properly)
-- if you want to mail me at work (you don't), use arjan (at) linux.intel.com
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