Messages in this thread | | | Subject | Re: [PATCH v18 21/25] x86/cet/shstk: Handle signals for shadow stack | From | "Yu, Yu-cheng" <> | Date | Mon, 1 Feb 2021 14:58:19 -0800 |
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On 2/1/2021 2:53 PM, Dave Hansen wrote: > On 1/27/21 1:25 PM, Yu-cheng Yu wrote: >> To deliver a signal, create a shadow stack restore token and put a restore >> token and the signal restorer address on the shadow stack. For sigreturn, >> verify the token and restore the shadow stack pointer. >> >> Introduce WRUSS, which is a kernel-mode instruction but writes directly to >> user shadow stack. It is used to construct the user signal stack as >> described above. >> >> Introduce a signal context extension struct 'sc_ext', which is used to save >> shadow stack restore token address and WAIT_ENDBR status. WAIT_ENDBR will >> be introduced later in the Indirect Branch Tracking (IBT) series, but add >> that into sc_ext now to keep the struct stable in case the IBT series is >> applied later. > > This changelog needs some work. It's got a lot of "what" and not enough > "why". > > Why do we need a token? > What function does it serve? > What does it protect against? > Why do we need a signal context extension? >
I will update it.
-- Yu-cheng
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