Re: [Fastboot] [PATCH] x86_64: Reload CS when startup_64 is used.

[Magnus Damm]

Hi Eric,

On 8/22/06, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
> In long mode the %cs is largely a relic.  However there are a few cases
> like lret where it matters that we have a valid value.  Without this
> patch it is possible to enter the kernel in startup_64 without setting
> %cs to a valid value.  With this patch we don't care what %cs value
> we enter the kernel with, so long as the cs shadow register indicates
> it is a privileged code segment.
>
> Thanks to Magnus Damm for finding this problem and posting the
> first workable patch.  I have moved the jump to set %cs down a
> few instructions so we don't need to take an extra jump.  Which
> keeps the code simpler.
>
> Signed-of-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>

While at it, could you please fix up the purgatory code in kexec-tools
to include this fix so we can boot older versions of the kernel too?

Thanks,

/ magnus
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