Messages in this thread | | | Date | Fri, 27 Aug 2021 20:46:35 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v29 23/32] x86/cet/shstk: Add user-mode shadow stack support |
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On Fri, Aug 27, 2021 at 11:37:34AM -0700, Yu, Yu-cheng wrote: > Right now, the kernel does lazy restore, and it waits until right before a > task goes back to ring-3 to restore xstates. If a task needs to write to > any xstate registers before that (e.g. for signals), it restores the whole > xstates first and clears TIF_NEED_FPU_LOAD, which will prevent xstates being > restored again later.
shstk_setup() allocates a shadow stack for the task and puts its pointer in MSR_IA32_PL3_SSP.
What does that have to do with a task having to write any xstate registers?
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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