[PATCH] powerpc: Add missing insn in swapcontext [BZ #20004]

[Paul E. Murphy]

On 04/28/2016 10:37 AM, Carlos O'Donell wrote:
> On 04/28/2016 10:36 AM, Paul E. Murphy wrote:
>> A missing instruction was discovered in the compat version of
>> swapcontext while running the GCC test suite.
>>
>> 2016-04-28  Paul E. Murphy  <murphyp@linux.vnet.ibm.com>
>> 	    Segher Boessenkool  <segher@gcc.gnu.org>
>>
>> 	[BZ #20004]
>> 	* sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S:
>> 	(__novec_swapcontext): Add missing load.
>> ---
>>  sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S b/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S
>> index a166dcc..a05a9cc 100644
>> --- a/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S
>> +++ b/sysdeps/unix/sysv/linux/powerpc/powerpc64/swapcontext.S
>> @@ -163,6 +163,7 @@ ENTRY(__novec_swapcontext)
>>    cmpdi r0,0
>>    bne	  L(nv_do_sigret)
>>  
>> +  ld	r8,.LC__dl_hwcap@toc(r2)
>>  # ifdef SHARED
>>  /* Load _rtld-global._dl_hwcap.  */
>>    ld    r8,RTLD_GLOBAL_RO_DL_HWCAP_OFFSET(r8)
>>
> 
> How did you test this?

A slightly hacked up, debate-ably correct, example provided by the
makecontext man page, which is modified to explicitly call the old
version.  I directly linked the generated object files.

Without this patch it segfaults.  With it, seemingly expected output.