Re: [PATCH v2] gdbserver: Clear X86_XSTATE_MPX bits in xcr0 on x32

[John Baldwin <jhb@FreeBSD.org>]

On 3/20/24 7:45 AM, Willgerodt, Felix wrote:
>> -----Original Message-----
>> From: H.J. Lu <hjl.tools@gmail.com>
>> Sent: Mittwoch, 20. März 2024 12:13
>> To: gdb-patches@sourceware.org
>> Cc: Willgerodt, Felix <felix.willgerodt@intel.com>; jhb@FreeBSD.org
>> Subject: [PATCH v2] gdbserver: Clear X86_XSTATE_MPX bits in xcr0 on x32
>>
>> Since MPX isn't available for x32, we should clear X86_XSTATE_MPX bits
>> on x32.
>>
>> 	PR server/31511
>> 	* linux-x86-low.cc (x86_linux_read_description): Clear
>> 	X86_XSTATE_MPX bits in xcr0 on x32.
>> ---
>>   gdbserver/linux-x86-low.cc | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/gdbserver/linux-x86-low.cc b/gdbserver/linux-x86-low.cc
>> index 3af0a009052..933d1fb012a 100644
>> --- a/gdbserver/linux-x86-low.cc
>> +++ b/gdbserver/linux-x86-low.cc
>> @@ -938,6 +938,10 @@ x86_linux_read_description (void)
>>   	  xcr0 = xstateregs[(I386_LINUX_XSAVE_XCR0_OFFSET
>>   			     / sizeof (uint64_t))];
>>
>> +	  /* No MPX on x32.  */
>> +	  if (machine == EM_X86_64 && !is_elf64)
>> +	    xcr0 &= ~X86_XSTATE_MPX;
>> +
>>   	  xsave_len = x86_xsave_length ();
>>
>>   	  /* Use PTRACE_GETREGSET if it is available.  */
>> --
>> 2.44.0
> 
> +1 from me.
> 
> Reviewed-by: Felix Willgerodt <felix.willgerodt@intel.com>

Looks good to me as well.

Approved-By: John Baldwin <jhb@FreeBSD.org>

-- 
John Baldwin