Re: [PATCH v3 1/4] GDB: Add gdb/arch/aarch64-pauth-linux.h

[Simon Marchi <simark@simark.ca>]

>> diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
>> index b85c25ecae1d..b5af281d8a40 100644
>> --- a/gdb/aarch64-linux-tdep.c
>> +++ b/gdb/aarch64-linux-tdep.c
>> @@ -54,6 +54,7 @@
>>   #include "arch/aarch64-gcs-linux.h"
>>   #include "arch/aarch64-mte.h"
>>   #include "arch/aarch64-mte-linux.h"
>> +#include "arch/aarch64-pauth-linux.h"
>>   #include "arch/aarch64-scalable-linux.h"
>>     #include "arch-utils.h"
>> @@ -1760,7 +1761,7 @@ aarch64_linux_core_read_description (struct gdbarch *gdbarch,
>>        have the correct target description with the correct SVE vector
>>        length.  */
>>     features.vq = aarch64_linux_core_read_vq_from_sections (gdbarch, abfd);
>> -  features.pauth = hwcap & AARCH64_HWCAP_PACA;
>> +  features.pauth = hwcap & HWCAP_PACA;

See comment below about HWCAP_PACA.

>> diff --git a/gdb/arch/aarch64-pauth-linux.h b/gdb/arch/aarch64-pauth-linux.h
>> new file mode 100644
>> index 000000000000..e973c79c8767
>> --- /dev/null
>> +++ b/gdb/arch/aarch64-pauth-linux.h
>> @@ -0,0 +1,31 @@
>> +/* Common Linux target-dependent definitions for AArch64 PAuth.
>> +
>> +   Copyright (C) 2019-2026 Free Software Foundation, Inc.
>> +
>> +   This file is part of GDB.
>> +
>> +   This program is free software; you can redistribute it and/or modify
>> +   it under the terms of the GNU General Public License as published by
>> +   the Free Software Foundation; either version 3 of the License, or
>> +   (at your option) any later version.
>> +
>> +   This program is distributed in the hope that it will be useful,
>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> +   GNU General Public License for more details.
>> +
>> +   You should have received a copy of the GNU General Public License
>> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
>> +
>> +#ifndef GDB_ARCH_AARCH64_PAUTH_LINUX_H
>> +#define GDB_ARCH_AARCH64_PAUTH_LINUX_H
>> +
>> +/* Feature check for Pointer Authentication Code Extension.  */
>> +#ifndef HWCAP_PACA
>> +#define HWCAP_PACA (1 << 30)
>> +#endif

As per the previous discussions, I'm not sure this definition of
HWCAP_PACA should be here.  For instance, what if another architecture
defines a HWCAP_PACA with a different meaning/value?  It should only be
seen by native code, so it should be somehwere in nat/.

For the same reason, I think that aarch64-linux-tdep.c should use a
constant named AARCH64_HWCAP_PACA, not HWCAP_PACA.  I thought this was
the conclusion of the previous discussions, there might have been a
misunderstanding.

The native files aarch64-linux-nat.c and linux-aarch64-low.cc can use
HWCAP_PACA though, because they see the definition from the system
headers (or worst case, a definition from nat/, to support compiling
against older kernels).

Simon