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    SubjectRe: [tip:x86/asm] x86/i386: Make sure stack-protector segment base is cache aligned

    * H. Peter Anvin <> wrote:

    > On 09/03/2009 01:45 PM, Jeremy Fitzhardinge wrote:
    > >
    > > Two problems:
    > >
    > > * gcc generates %gs: references for stack-protector, but we use %fs
    > > for percpu data (because restoring %fs is faster if it's a null
    > > selector; TLS uses %gs). I guess we could use %fs if
    > > !CONFIG_CC_STACKPROTECTOR, or %gs if we are using it (though that
    > > has some fiddly ramifications for things like ptrace).
    > Well, by touching two segments we're getting the worst of both
    > worlds, so at least assuming some significant number of real-world
    > deployments use CC_STACKPROTECTOR, we really don't want to
    > pessimize that case too much.

    Fedora has stackprotector enabled so it's used in a widespread way.


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