[PATCH 1/2] x86-64: Add shadow stack base and limit to tcbhead_t

[H.J. Lu]

On Tue, Jul 24, 2018 at 1:49 PM, Carlos O'Donell <carlos@redhat.com> wrote:
> On 07/21/2018 10:20 AM, H.J. Lu wrote:
>> This will be used to implement shadow stack switching by getcontext,
>> makecontext, setcontext and swapcontext.
>>
>>       * sysdeps/i386/nptl/tcb-offsets.sym (SSP_BASE_OFFSET): New.
>>       * sysdeps/i386/nptl/tls.h (tcbhead_t): Replace __glibc_reserved2
>>       with ssp_base.
>>       * sysdeps/x86_64/nptl/tcb-offsets.sym (SSP_BASE_OFFSET): New.
>>       * sysdeps/x86_64/nptl/tls.h (tcbhead_t): Replace __glibc_reserved2
>>       with ssp_base.
>
> Looks good to me.
>
> Reviewed-by: Carlos O'Donell <carlos@redhat.com>
>

We find a testcase where setcontext failed when there are gaps above
and below the newly allocated shadow stack.  Here is the updated patch
to add shadow stack base and limit to tcbhead_t.

We need to find room for shadow stack base and upper limit in i386
tcbhead_t.  I have some ideas.   For now, I'd like to get x86-64 working
first.

OK for master branch?

Thanks.

-- 
H.J.
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