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

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

On 17/02/2026 06:00, Thiago Jung Bauermann wrote:
> The code supporting Pointer Authentication duplicates the definition of
> AARCH64_HWCAP_PACA and of AARCH64_LINUX_SIZEOF_PAUTH between GDB and
> gdbserver, so add new header to host those definitions.
> 
> Also, rename AARCH64_HWCAP_PACA to HWCAP_PACA and only define it if it
> isn't already defined by the system headers, as is done for other HWCAP
> constants.
> 
> Suggested-by: Luis <luis.machado.foss@gmail.com>
> ---
>   gdb/Makefile.in                |  1 +
>   gdb/aarch64-linux-nat.c        |  3 ++-
>   gdb/aarch64-linux-tdep.c       |  3 ++-
>   gdb/aarch64-linux-tdep.h       |  6 ------
>   gdb/arch/aarch64-pauth-linux.h | 31 +++++++++++++++++++++++++++++++
>   gdb/arch/aarch64.h             |  3 ---
>   gdbserver/linux-aarch64-low.cc |  8 +++-----
>   7 files changed, 39 insertions(+), 16 deletions(-)
>   create mode 100644 gdb/arch/aarch64-pauth-linux.h
> 
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 2aa95be968ac..8f8a95beccc3 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -1306,6 +1306,7 @@ HFILES_NO_SRCDIR = \
>   	arch/aarch64-insn.h \
>   	arch/aarch64-mte.h \
>   	arch/aarch64-mte-linux.h \
> +	arch/aarch64-pauth-linux.h \
>   	arch/aarch64-scalable-linux.h \
>   	arch/amd64.h \
>   	arch/amd64-linux-tdesc.h \
> diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
> index 028de981588b..d310d3e814b2 100644
> --- a/gdb/aarch64-linux-nat.c
> +++ b/gdb/aarch64-linux-nat.c
> @@ -53,6 +53,7 @@
>   
>   #include "arch/aarch64-gcs-linux.h"
>   #include "arch/aarch64-mte-linux.h"
> +#include "arch/aarch64-pauth-linux.h"
>   
>   #include "nat/aarch64-mte-linux-ptrace.h"
>   #include "arch/aarch64-scalable-linux.h"
> @@ -1012,7 +1013,7 @@ aarch64_linux_nat_target::read_description ()
>        or the streaming vector length, depending on whether streaming mode is
>        active or not.  */
>     features.vq = aarch64_sve_get_vq (tid);
> -  features.pauth = hwcap & AARCH64_HWCAP_PACA;
> +  features.pauth = hwcap & HWCAP_PACA;
>     features.gcs = features.gcs_linux = hwcap & HWCAP_GCS;
>     features.mte = hwcap2 & HWCAP2_MTE;
>     features.tls = aarch64_tls_register_count (tid);
> 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;
>     features.gcs = features.gcs_linux = hwcap & HWCAP_GCS;
>     features.mte = hwcap2 & HWCAP2_MTE;
>     features.fpmr = hwcap2 & HWCAP2_FPMR;
> diff --git a/gdb/aarch64-linux-tdep.h b/gdb/aarch64-linux-tdep.h
> index e926687ff6eb..b99fe91f36bd 100644
> --- a/gdb/aarch64-linux-tdep.h
> +++ b/gdb/aarch64-linux-tdep.h
> @@ -33,16 +33,10 @@
>      alignment.  */
>   #define AARCH64_LINUX_SIZEOF_FPREGSET (33 * V_REGISTER_SIZE)
>   
> -/* The pauth regset consists of 2 X sized registers.  */
> -#define AARCH64_LINUX_SIZEOF_PAUTH (2 * X_REGISTER_SIZE)
> -
>   /* The MTE regset consists of a 64-bit register.  */
>   #define AARCH64_LINUX_SIZEOF_MTE_REGSET (8)
>   
>   extern const struct regset aarch64_linux_gregset;
>   extern const struct regset aarch64_linux_fpregset;
>   
> -/* Matches HWCAP_PACA in kernel header arch/arm64/include/uapi/asm/hwcap.h.  */
> -#define AARCH64_HWCAP_PACA (1 << 30)
> -
>   #endif /* GDB_AARCH64_LINUX_TDEP_H */
> 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
> +
> +/* The pauth regset consists of 2 64-bit registers.  */
> +#define AARCH64_LINUX_SIZEOF_PAUTH 16
> +
> +#endif /* GDB_ARCH_AARCH64_PAUTH_LINUX_H */
> diff --git a/gdb/arch/aarch64.h b/gdb/arch/aarch64.h
> index 0e9715a4268a..7856d95a93b1 100644
> --- a/gdb/arch/aarch64.h
> +++ b/gdb/arch/aarch64.h
> @@ -178,9 +178,6 @@ enum aarch64_regnum
>   #define AARCH64_PAUTH_DMASK_HIGH_REGNUM(pauth_reg_base) (pauth_reg_base + 2)
>   #define AARCH64_PAUTH_CMASK_HIGH_REGNUM(pauth_reg_base) (pauth_reg_base + 3)
>   
> -/* This size is only meant for Linux, not bare metal.  QEMU exposes 4 masks.  */
> -#define AARCH64_PAUTH_REGS_SIZE (16)
> -
>   #define AARCH64_X_REGS_NUM 31
>   #define AARCH64_V_REGS_NUM 32
>   #define AARCH64_SVE_Z_REGS_NUM AARCH64_V_REGS_NUM
> diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
> index b19e605f55d6..69aaabc1a8f9 100644
> --- a/gdbserver/linux-aarch64-low.cc
> +++ b/gdbserver/linux-aarch64-low.cc
> @@ -45,6 +45,7 @@
>   #include "linux-aarch32-tdesc.h"
>   #include "linux-aarch64-tdesc.h"
>   #include "nat/aarch64-mte-linux-ptrace.h"
> +#include "arch/aarch64-pauth-linux.h"
>   #include "nat/aarch64-scalable-linux-ptrace.h"
>   #include "tdesc.h"
>   
> @@ -952,7 +953,7 @@ aarch64_adjust_register_sets (const struct aarch64_features &features)
>   	  break;
>   	case NT_ARM_PAC_MASK:
>   	  if (features.pauth)
> -	    regset->size = AARCH64_PAUTH_REGS_SIZE;
> +	    regset->size = AARCH64_LINUX_SIZEOF_PAUTH;
>   	  break;
>   	case NT_ARM_TAGGED_ADDR_CTRL:
>   	  if (features.mte)
> @@ -984,9 +985,6 @@ aarch64_adjust_register_sets (const struct aarch64_features &features)
>       }
>   }
>   
> -/* Matches HWCAP_PACA in kernel header arch/arm64/include/uapi/asm/hwcap.h.  */
> -#define AARCH64_HWCAP_PACA (1 << 30)
> -
>   /* Implementation of linux target ops method "low_arch_setup".  */
>   
>   void
> @@ -1005,7 +1003,7 @@ aarch64_target::low_arch_setup ()
>   
>         features.vq = aarch64_sve_get_vq (tid);
>         /* A-profile PAC is 64-bit only.  */
> -      features.pauth = linux_get_hwcap (pid, 8) & AARCH64_HWCAP_PACA;
> +      features.pauth = linux_get_hwcap (pid, 8) & HWCAP_PACA;
>         /* A-profile MTE is 64-bit only.  */
>         features.mte = linux_get_hwcap2 (pid, 8) & HWCAP2_MTE;
>         features.tls = aarch64_tls_register_count (tid);

Thanks for the cleanup. This one is OK.

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