Re: [PATCH v3 3/4] GDB: aarch64-linux: Move definition of struct user_gcs

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

On 17/02/2026 06:01, Thiago Jung Bauermann wrote:
> Only native code should use struct user_gcs, so its definition should be
> in a native-specific file and not in a file under gdb/arch/.
> 
> To fix this problem, create gdb/nat/aarch64-gcs-linux-ptrace.h and move
> the struct user_gcs definition to it, as suggested by Luis.
> 
> To fix the use of struct user_gcs in gdb/aarch64-linuxt-dep.c, define a
> macro with the size of the GCS regset in gdb/arch/aarch64-gcs-linux.h
> and use it in aarch64-linux-tdep.c, as is done for other regsets and
> following a suggestion from Simon Marchi.
> 
> Suggested-by: Luis <luis.machado.foss@gmail.com>
> Suggested-by: Simon Marchi <simark@simark.ca>
> ---
> Changes since v2:
> - Don't rename gdb/arch/aarch64-gcs-linux.h to gdb/arch/aarch64-linux.h,
>    as suggested by Luis.
> - Create gdb/nat/aarch64-gcs-linux-ptrace.h to contain definition of
>    struct user_gcs, as suggested by Luis.
> - Don't rename HWCAP_GCS to AARCH64_HWCAP_GCS, as suggested by Luis.
> - Move definition of AARCH64_LINUX_SIZEOF_GCS_REGSET from
>    gdb/aarch64-linux-tdep.h to gdb/arch/aarch64-gcs-linux.h, as suggested
>    by Luis.
> - Move changes to HWCAP_PACA to separate patch.
> 
>   gdb/Makefile.in                    |  1 +
>   gdb/aarch64-linux-nat.c            |  1 +
>   gdb/aarch64-linux-tdep.c           |  5 ++--
>   gdb/arch/aarch64-gcs-linux.h       | 17 ++-----------
>   gdb/nat/aarch64-gcs-linux-ptrace.h | 40 ++++++++++++++++++++++++++++++
>   gdbserver/linux-aarch64-low.cc     |  1 +
>   6 files changed, 48 insertions(+), 17 deletions(-)
>   create mode 100644 gdb/nat/aarch64-gcs-linux-ptrace.h
> 
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index f0f10e3946bf..0ac45bd9d326 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -1550,6 +1550,7 @@ HFILES_NO_SRCDIR = \
>   	nat/aarch64-hw-point.h \
>   	nat/aarch64-linux.h \
>   	nat/aarch64-linux-hw-point.h \
> +	nat/aarch64-gcs-linux-ptrace.h \
>   	nat/aarch64-mte-linux-ptrace.h \
>   	nat/aarch64-scalable-linux-ptrace.h \
>   	nat/aarch64-scalable-linux-sigcontext.h \
> diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
> index 9f85d96b59ef..a49b82ca43c8 100644
> --- a/gdb/aarch64-linux-nat.c
> +++ b/gdb/aarch64-linux-nat.c
> @@ -34,6 +34,7 @@
>   #include "arch/arm.h"
>   #include "nat/aarch64-linux.h"
>   #include "nat/aarch64-linux-hw-point.h"
> +#include "nat/aarch64-gcs-linux-ptrace.h"
>   #include "nat/aarch64-scalable-linux-ptrace.h"
>   
>   #include "elf/external.h"
> diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
> index c17ccbc66220..f0935cbd67e8 100644
> --- a/gdb/aarch64-linux-tdep.c
> +++ b/gdb/aarch64-linux-tdep.c
> @@ -1736,8 +1736,9 @@ aarch64_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
>   	  gcs_regmap, regcache_supply_regset, regcache_collect_regset
>   	};
>   
> -      cb (".reg-aarch-gcs", sizeof (user_gcs), sizeof (user_gcs),
> -	  &aarch64_linux_gcs_regset, "GCS registers", cb_data);
> +      cb (".reg-aarch-gcs", AARCH64_LINUX_SIZEOF_GCS_REGSET,
> +	  AARCH64_LINUX_SIZEOF_GCS_REGSET, &aarch64_linux_gcs_regset,
> +	  "GCS registers", cb_data);
>       }
>   }
>   
> diff --git a/gdb/arch/aarch64-gcs-linux.h b/gdb/arch/aarch64-gcs-linux.h
> index b31fc32daa03..015a49b25976 100644
> --- a/gdb/arch/aarch64-gcs-linux.h
> +++ b/gdb/arch/aarch64-gcs-linux.h
> @@ -20,25 +20,12 @@
>   #ifndef GDB_ARCH_AARCH64_GCS_LINUX_H
>   #define GDB_ARCH_AARCH64_GCS_LINUX_H
>   
> -#include <stdint.h>
> -
>   /* Feature check for Guarded Control Stack.  */
>   #ifndef HWCAP_GCS
>   #define HWCAP_GCS (1ULL << 32)
>   #endif
>   
> -/* Make sure we only define these if the kernel header doesn't.  */
> -#ifndef GCS_MAGIC
> -
> -/* GCS state (NT_ARM_GCS).  */
> -
> -struct user_gcs
> -{
> -  uint64_t features_enabled;
> -  uint64_t features_locked;
> -  uint64_t gcspr_el0;
> -};
> -
> -#endif /* GCS_MAGIC */
> +/* The GCS regset consists of 3 64-bit registers.  */
> +#define AARCH64_LINUX_SIZEOF_GCS_REGSET (3 * 8)
>   
>   #endif /* GDB_ARCH_AARCH64_GCS_LINUX_H */
> diff --git a/gdb/nat/aarch64-gcs-linux-ptrace.h b/gdb/nat/aarch64-gcs-linux-ptrace.h
> new file mode 100644
> index 000000000000..f45a1059cd0a
> --- /dev/null
> +++ b/gdb/nat/aarch64-gcs-linux-ptrace.h
> @@ -0,0 +1,40 @@
> +/* Common native Linux definitions for AArch64 Guarded Control Stack.
> +
> +   Copyright (C) 2025-2026 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_NAT_AARCH64_GCS_LINUX_PTRACE_H
> +#define GDB_NAT_AARCH64_GCS_LINUX_PTRACE_H
> +
> +#include <stdint.h>
> +#include <asm/ptrace.h>
> +
> +/* Make sure we only define these if the kernel header doesn't.  */
> +#ifndef GCS_MAGIC
> +
> +/* GCS state (NT_ARM_GCS).  */
> +
> +struct user_gcs
> +{
> +  uint64_t features_enabled;
> +  uint64_t features_locked;
> +  uint64_t gcspr_el0;
> +};
> +
> +#endif /* GCS_MAGIC */
> +
> +#endif /* GDB_NAT_AARCH64_GCS_LINUX_PTRACE_H */
> diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
> index 6b61f6d5a815..55e55b2df0ab 100644
> --- a/gdbserver/linux-aarch64-low.cc
> +++ b/gdbserver/linux-aarch64-low.cc
> @@ -45,6 +45,7 @@
>   #include "arch/aarch64-scalable-linux.h"
>   #include "linux-aarch32-tdesc.h"
>   #include "linux-aarch64-tdesc.h"
> +#include "nat/aarch64-gcs-linux-ptrace.h"
>   #include "nat/aarch64-mte-linux-ptrace.h"
>   #include "arch/aarch64-pauth-linux.h"
>   #include "nat/aarch64-scalable-linux-ptrace.h"

Thanks. Also OK.

Approved-By: Luis Machado <luis.machado.foss@gmail.com>