Re: ia32_sysenter_target does not preserve EFLAGS

[Denys Vlasenko]

On Sat, Mar 28, 2015 at 1:39 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> What part of "don't leak kernel data" did you have trouble understanding?
>
> IOW, this is a *security* issue. Stop arguing for crazy shit.

We can zero the registers instead of saving/restoring them.
push/pop pair takes 1-2 cycles at best, whereas
on four-issue CPUs "xor reg,reg" has throughput of four
instructions at a time, often even not requiring
an execution unit.
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