Messages in this thread | | | From | Andy Lutomirski <> | Date | Tue, 26 Apr 2016 15:33:30 -0700 | Subject | Re: [PATCH 5/8] x86/arch_prctl/64: Remove FSBASE/GSBASE < 4G optimization |
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On Tue, Apr 26, 2016 at 1:50 PM, Andi Kleen <andi@firstfloor.org> wrote: > On Tue, Apr 26, 2016 at 12:23:28PM -0700, Andy Lutomirski wrote: >> As far as I know, the optimization doesn't work on any modern distro >> because modern distros use high addresses for ASLR. Remove it. > > I disagree with this patch. For example it will be a regression > for static executables. And randomly making old systems slower is a bad > idea.
That's odd. statically linked glibc uses low addresses, even in PIE mode. I wonder why.
In any event, this isn't actually much of a performance regression, it has no effect on normal dynamically linked programs, and it's a considerably simplification, so I still think it's a good idea. It also removes some nasty special cases from code that is already way too full of special cases for comfort.
--Andy
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