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

[Luis <luis.machado.foss@gmail.com>]

On 21/02/2026 15:57, Simon Marchi wrote:
>>> 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.

I don´t recall the discussions touching renaming/moving of these 
constants. But I see your point. I just don´t think we should block this 
series from going in on that particular snag. We should try a 
refactoring as a follow on.

On the naming, I don´t mind adding an AARCH64 prefix, but I find it 
unlikely we will run into a naming collision given BSD uses equivalent 
constants. Again, not disputing the matter of what is technically 
correct or not.

> 
> 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