Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 22 Mar 2018 16:07:53 +0000 | Subject | Re: [PATCH 14/15] x86/fsgsbase/64: Support legacy behavior when FS/GS updated by ptracer |
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On Thu, Mar 22, 2018 at 3:45 PM, Bae, Chang Seok <chang.seok.bae@intel.com> wrote: > On 3/21/18, 18:41, "Andy Lutomirski" <luto@kernel.org> wrote: >> mov to gs changes GSBASE even if GS was unchanged. > In GDB, ptrace (syscall) doesn't happen when FS/GS unchanged as > its (context) cache seems to be first checked. This does not allow to > preserve GSBASE as you know. > >> But it's not clear to me that you've identified any case where >> emulating this behavior is useful. > One argument I heard is (if debugging a legacy application) user > might want to (indirectly) access LDT during inferior call and this > mov to fs/gs has been useful (maybe needed). > >
But your patch doesn't actually do this, since gdb will just do SETREGS anyway, right?
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