Re: [PATCH 2/2] x86_64,signal: Remove 'fs' and 'gs' from sigcontext

[H. Peter Anvin]

Because you are doing something weird (like Pin, for example) and take an asynchronous fault?

On July 12, 2014 11:37:48 AM PDT, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
>> This seems like it's asking for trouble.  I think wxe'd have to
>> separately save the selectors and the base registers to avoid
>breaking
>> something, especially once wrgsbase, etc are enabled.
>
>I agree, it would likely break existing code.
>
>> Linus, for context, the other patch in this series saves and restores
>> SS. 
>
>> Without that, 64-bit sigreturn to a nondefault stack segment is
>> basically impossible.  
>
>Why would you ever want to do that?
>
>-Andi

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