Re: ia32_sysenter_target does not preserve EFLAGS

[Linus Torvalds]

On Fri, Mar 27, 2015 at 1:16 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
> Does it matter on 32-bit kernels?  There's no swapgs, so IRQs should
> still be safe, and we have a real stack pointer before sysexit.

Fair enough.  On 32-bit, the only worry is the race between "return to
user space" and "something set a thread flag", resulting in delayed
signals and/or higher scheduling latency etc. So on 32-bit, the bug is
much less of an issue, I agree.

So yeah, using sysretl instead of sti+sysexit on 64-bit sounds more
reasonable given the potential worry about sti+sysexit atomicity in
the presense of nmi's.

                      Linus
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