[PATCH v3 0/4] GDB: aarch64-linux: Some header fixes

[PATCH v3 0/4] GDB: aarch64-linux: Some header fixes

[Thiago Jung Bauermann]

Patch 4 fixes the problem I set out to fix in v1¹ and v2².

Patches 1 and 2 are new in v3 and add new feature-specific AArch64 headers
in gdb/arch as suggested by Luis in his review o v2.

Patch 3 is v2's patch 1 and grew out of Simon's patch review of v1, where
he noted that files in gdb/arch/ shouldn't depend on arch-specific include
files.

Thiago Jung Bauermann (4):
  GDB: Add gdb/arch/aarch64-pauth-linux.h
  GDB: Add gdb/arch/aarch64-fpmr-linux.h
  GDB: aarch64-linux: Move definition of struct user_gcs
  GDB: aarch64-linux: Fix build failure on musl systems

 gdb/Makefile.in                    |  3 +++
 gdb/aarch64-linux-nat.c            |  5 +++-
 gdb/aarch64-linux-tdep.c           |  9 ++++---
 gdb/aarch64-linux-tdep.h           |  6 -----
 gdb/arch/aarch64-fpmr-linux.h      | 28 +++++++++++++++++++++
 gdb/arch/aarch64-gcs-linux.h       | 17 ++-----------
 gdb/arch/aarch64-pauth-linux.h     | 31 ++++++++++++++++++++++++
 gdb/arch/aarch64.h                 |  8 ------
 gdb/nat/aarch64-gcs-linux-ptrace.h | 39 ++++++++++++++++++++++++++++++
 gdbserver/linux-aarch64-low.cc     | 10 ++++----
 gdbsupport/config.in               |  3 +++
 gdbsupport/configure               | 36 +++++++++++++++++++++++++++
 gdbsupport/configure.ac            | 19 +++++++++++++++
 13 files changed, 176 insertions(+), 38 deletions(-)
 create mode 100644 gdb/arch/aarch64-fpmr-linux.h
 create mode 100644 gdb/arch/aarch64-pauth-linux.h
 create mode 100644 gdb/nat/aarch64-gcs-linux-ptrace.h

¹ https://inbox.sourceware.org/gdb-patches/20260211045853.1436881-1-thiago.bauermann@linaro.org/
² https://inbox.sourceware.org/gdb-patches/20260214045504.361392-1-thiago.bauermann@linaro.org/

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

[Thiago Jung Bauermann]

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);

[PATCH v3 2/4] GDB: Add gdb/arch/aarch64-fpmr-linux.h

[Thiago Jung Bauermann]

GDB conditionally defines HWCAP2_FPMR in gdb/arch/aarch64.h, but that's
not the best place for it since it's a Linux-specific definition.

Add a new Linux- and feature-specific header to contain it.

Suggested-by: Luis <luis.machado.foss@gmail.com>
---
 gdb/Makefile.in                |  1 +
 gdb/aarch64-linux-nat.c        |  1 +
 gdb/aarch64-linux-tdep.c       |  1 +
 gdb/arch/aarch64-fpmr-linux.h  | 28 ++++++++++++++++++++++++++++
 gdb/arch/aarch64.h             |  5 -----
 gdbserver/linux-aarch64-low.cc |  1 +
 6 files changed, 32 insertions(+), 5 deletions(-)
 create mode 100644 gdb/arch/aarch64-fpmr-linux.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 8f8a95beccc3..f0f10e3946bf 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1301,6 +1301,7 @@ HFILES_NO_SRCDIR = \
 	amdgpu-tdep.h \
 	annotate.h \
 	arch/aarch32.h \
+	arch/aarch64-fpmr-linux.h \
 	arch/aarch64-gcs-linux.h \
 	arch/aarch64.h \
 	arch/aarch64-insn.h \
diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index d310d3e814b2..9f85d96b59ef 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -51,6 +51,7 @@
 #include "gdb_proc_service.h"
 #include "arch-utils.h"
 
+#include "arch/aarch64-fpmr-linux.h"
 #include "arch/aarch64-gcs-linux.h"
 #include "arch/aarch64-mte-linux.h"
 #include "arch/aarch64-pauth-linux.h"
diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index b5af281d8a40..c17ccbc66220 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -51,6 +51,7 @@
 #include "record-full.h"
 #include "linux-record.h"
 
+#include "arch/aarch64-fpmr-linux.h"
 #include "arch/aarch64-gcs-linux.h"
 #include "arch/aarch64-mte.h"
 #include "arch/aarch64-mte-linux.h"
diff --git a/gdb/arch/aarch64-fpmr-linux.h b/gdb/arch/aarch64-fpmr-linux.h
new file mode 100644
index 000000000000..d3040fa263e4
--- /dev/null
+++ b/gdb/arch/aarch64-fpmr-linux.h
@@ -0,0 +1,28 @@
+/* Common Linux target-dependent definitions for AArch64 FPMR.
+
+   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_ARCH_AARCH64_FPMR_LINUX_H
+#define GDB_ARCH_AARCH64_FPMR_LINUX_H
+
+/* Feature check for Floating Point Mode Register.  */
+#ifndef HWCAP2_FPMR
+#define HWCAP2_FPMR (1ULL << 48)
+#endif /* HWCAP2_FPMR */
+
+#endif /* GDB_ARCH_AARCH64_FPMR_LINUX_H */
diff --git a/gdb/arch/aarch64.h b/gdb/arch/aarch64.h
index 7856d95a93b1..c9a89ac40986 100644
--- a/gdb/arch/aarch64.h
+++ b/gdb/arch/aarch64.h
@@ -243,9 +243,4 @@ enum aarch64_regnum
 /* Size of the SME2 ZT0 register in bytes.  */
 #define AARCH64_SME2_ZT0_SIZE 64
 
-/* Feature check for Floating Point Mode Register.  */
-#ifndef HWCAP2_FPMR
-#define HWCAP2_FPMR (1ULL << 48)
-#endif /* HWCAP2_FPMR */
-
 #endif /* GDB_ARCH_AARCH64_H */
diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
index 69aaabc1a8f9..6b61f6d5a815 100644
--- a/gdbserver/linux-aarch64-low.cc
+++ b/gdbserver/linux-aarch64-low.cc
@@ -39,6 +39,7 @@
 
 #include "gdb_proc_service.h"
 #include "arch/aarch64.h"
+#include "arch/aarch64-fpmr-linux.h"
 #include "arch/aarch64-gcs-linux.h"
 #include "arch/aarch64-mte-linux.h"
 #include "arch/aarch64-scalable-linux.h"

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

[Thiago Jung Bauermann]

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"

[PATCH v3 4/4] GDB: aarch64-linux: Fix build failure on musl systems

[Thiago Jung Bauermann]

When building against musl (e.g. on Alpine Linux), the following error
happens:

    CXX    linux-aarch64-low.o
  In file included from /home/bauermann/src/binutils-gdb/gdbserver/linux-aarch64-low.cc:48:
  /home/bauermann/src/binutils-gdb/gdbserver/../gdb/nat/aarch64-gcs-linux-ptrace.h:31:8: error: redefinition of 'struct user_gcs'
     31 | struct user_gcs
        |        ^~~~~~~~
  In file included from /home/bauermann/src/binutils-gdb/gdbserver/linux-aarch64-low.cc:35:
  /usr/include/asm/ptrace.h:329:8: note: previous definition of 'struct user_gcs'
    329 | struct user_gcs {
        |        ^~~~~~~~
  make[2]: *** [Makefile:565: linux-aarch64-low.o] Error 1

aarch64-linux-tdep.c fails to build in the same way.  This happens
because aarch64-linux.h uses GCS_MAGIC to see whether the system
headers have GCS-related definitions.  The problem is that GCS_MAGIC is
defined in <asm/sigcontext.h> while struct gcs_user is defined in
<asm/ptrace.h>.  It's fine on glibc systems because in the set of system
headers that linux-aarch64-low.cc and aarch64-linux-tdep.c include,
<asm/sigcontext.h> ends up being included implicitly as well.  This
doesn't happen when using musl's headers though.

There isn't a macro in <asm/ptrace.h> whose presence is correlated with
the presence of the struct user_gcs definition, so a configure check is
needed to detect it and conditionally define the struct.

Note that there's another build issue with musl, described in
PR gdb/33747 affecting compilation of gdb/ser-unix.c.  In order to be
able to test this patch, I applied the patch in comment 11 there.

Tested with a native build on an Alpine Linux aarch64 system, and also
verified that all gdb.arch/aarch64-gcs*.exp tests pass on it.

Co-authored-by: Chris Packham <judge.packham@gmail.com>
---
Changes since v2:
- It's the same patch except that the header changed is
  gdb/nat/aarch64-gcs-linux-ptrace.h rather than gdb/nat/aarch64-linux.h,
  which doesn't exist in this version of the patch series.

 gdb/nat/aarch64-gcs-linux-ptrace.h |  5 ++---
 gdbsupport/config.in               |  3 +++
 gdbsupport/configure               | 36 ++++++++++++++++++++++++++++++
 gdbsupport/configure.ac            | 19 ++++++++++++++++
 4 files changed, 60 insertions(+), 3 deletions(-)

diff --git a/gdb/nat/aarch64-gcs-linux-ptrace.h b/gdb/nat/aarch64-gcs-linux-ptrace.h
index f45a1059cd0a..f3dda08a1d27 100644
--- a/gdb/nat/aarch64-gcs-linux-ptrace.h
+++ b/gdb/nat/aarch64-gcs-linux-ptrace.h
@@ -23,8 +23,7 @@
 #include <stdint.h>
 #include <asm/ptrace.h>
 
-/* Make sure we only define these if the kernel header doesn't.  */
-#ifndef GCS_MAGIC
+#ifndef HAVE_STRUCT_USER_GCS
 
 /* GCS state (NT_ARM_GCS).  */
 
@@ -35,6 +34,6 @@ struct user_gcs
   uint64_t gcspr_el0;
 };
 
-#endif /* GCS_MAGIC */
+#endif /* HAVE_STRUCT_USER_GCS */
 
 #endif /* GDB_NAT_AARCH64_GCS_LINUX_PTRACE_H */
diff --git a/gdbsupport/config.in b/gdbsupport/config.in
index 0beacf22c057..2957ee0f0301 100644
--- a/gdbsupport/config.in
+++ b/gdbsupport/config.in
@@ -271,6 +271,9 @@
 /* Define to 1 if `st_blocks' is a member of `struct stat'. */
 #undef HAVE_STRUCT_STAT_ST_BLOCKS
 
+/* Define to 1 if your system has struct user_gcs. */
+#undef HAVE_STRUCT_USER_GCS
+
 /* Define to 1 if you have the <sys/param.h> header file. */
 #undef HAVE_SYS_PARAM_H
 
diff --git a/gdbsupport/configure b/gdbsupport/configure
index 05ad00f48c4f..584a80ef8255 100755
--- a/gdbsupport/configure
+++ b/gdbsupport/configure
@@ -14307,6 +14307,42 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 
+# Check for `struct user_gcs`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for struct user_gcs" >&5
+$as_echo_n "checking for struct user_gcs... " >&6; }
+if ${gdb_cv_struct_user_gcs+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <sys/ptrace.h>
+	 #include <asm/ptrace.h>
+int
+main ()
+{
+struct user_gcs u;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  gdb_cv_struct_user_gcs=yes
+else
+  gdb_cv_struct_user_gcs=no
+
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gdb_cv_struct_user_gcs" >&5
+$as_echo "$gdb_cv_struct_user_gcs" >&6; }
+if test "$gdb_cv_struct_user_gcs" = yes; then
+
+$as_echo "#define HAVE_STRUCT_USER_GCS 1" >>confdefs.h
+
+fi
+
 # Set the 'development' global.
 . $srcdir/../bfd/development.sh
 
diff --git a/gdbsupport/configure.ac b/gdbsupport/configure.ac
index 5491b8f3f10a..6c06832f0913 100644
--- a/gdbsupport/configure.ac
+++ b/gdbsupport/configure.ac
@@ -68,6 +68,25 @@ GDB_AC_PTRACE
 AM_GDB_COMPILER_TYPE
 AM_GDB_WARNINGS
 
+# Check for `struct user_gcs`
+AC_CACHE_CHECK(
+  [for struct user_gcs],
+  [gdb_cv_struct_user_gcs],
+  [AC_COMPILE_IFELSE(
+     [AC_LANG_PROGRAM(
+	[#include <sys/ptrace.h>
+	 #include <asm/ptrace.h>],
+	[struct user_gcs u;]
+      )],
+     [gdb_cv_struct_user_gcs=yes],
+     [gdb_cv_struct_user_gcs=no]
+  )]
+)
+if test "$gdb_cv_struct_user_gcs" = yes; then
+  AC_DEFINE(HAVE_STRUCT_USER_GCS, 1,
+	    [Define to 1 if your system has struct user_gcs.])
+fi
+
 # Set the 'development' global.
 . $srcdir/../bfd/development.sh
 

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

[Luis]

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>

Re: [PATCH v3 2/4] GDB: Add gdb/arch/aarch64-fpmr-linux.h

[Luis]

On 17/02/2026 06:01, Thiago Jung Bauermann wrote:
> GDB conditionally defines HWCAP2_FPMR in gdb/arch/aarch64.h, but that's
> not the best place for it since it's a Linux-specific definition.
> 
> Add a new Linux- and feature-specific header to contain it.
> 
> Suggested-by: Luis <luis.machado.foss@gmail.com>
> ---
>   gdb/Makefile.in                |  1 +
>   gdb/aarch64-linux-nat.c        |  1 +
>   gdb/aarch64-linux-tdep.c       |  1 +
>   gdb/arch/aarch64-fpmr-linux.h  | 28 ++++++++++++++++++++++++++++
>   gdb/arch/aarch64.h             |  5 -----
>   gdbserver/linux-aarch64-low.cc |  1 +
>   6 files changed, 32 insertions(+), 5 deletions(-)
>   create mode 100644 gdb/arch/aarch64-fpmr-linux.h
> 
> diff --git a/gdb/Makefile.in b/gdb/Makefile.in
> index 8f8a95beccc3..f0f10e3946bf 100644
> --- a/gdb/Makefile.in
> +++ b/gdb/Makefile.in
> @@ -1301,6 +1301,7 @@ HFILES_NO_SRCDIR = \
>   	amdgpu-tdep.h \
>   	annotate.h \
>   	arch/aarch32.h \
> +	arch/aarch64-fpmr-linux.h \
>   	arch/aarch64-gcs-linux.h \
>   	arch/aarch64.h \
>   	arch/aarch64-insn.h \
> diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
> index d310d3e814b2..9f85d96b59ef 100644
> --- a/gdb/aarch64-linux-nat.c
> +++ b/gdb/aarch64-linux-nat.c
> @@ -51,6 +51,7 @@
>   #include "gdb_proc_service.h"
>   #include "arch-utils.h"
>   
> +#include "arch/aarch64-fpmr-linux.h"
>   #include "arch/aarch64-gcs-linux.h"
>   #include "arch/aarch64-mte-linux.h"
>   #include "arch/aarch64-pauth-linux.h"
> diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
> index b5af281d8a40..c17ccbc66220 100644
> --- a/gdb/aarch64-linux-tdep.c
> +++ b/gdb/aarch64-linux-tdep.c
> @@ -51,6 +51,7 @@
>   #include "record-full.h"
>   #include "linux-record.h"
>   
> +#include "arch/aarch64-fpmr-linux.h"
>   #include "arch/aarch64-gcs-linux.h"
>   #include "arch/aarch64-mte.h"
>   #include "arch/aarch64-mte-linux.h"
> diff --git a/gdb/arch/aarch64-fpmr-linux.h b/gdb/arch/aarch64-fpmr-linux.h
> new file mode 100644
> index 000000000000..d3040fa263e4
> --- /dev/null
> +++ b/gdb/arch/aarch64-fpmr-linux.h
> @@ -0,0 +1,28 @@
> +/* Common Linux target-dependent definitions for AArch64 FPMR.
> +
> +   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_ARCH_AARCH64_FPMR_LINUX_H
> +#define GDB_ARCH_AARCH64_FPMR_LINUX_H
> +
> +/* Feature check for Floating Point Mode Register.  */
> +#ifndef HWCAP2_FPMR
> +#define HWCAP2_FPMR (1ULL << 48)
> +#endif /* HWCAP2_FPMR */
> +
> +#endif /* GDB_ARCH_AARCH64_FPMR_LINUX_H */
> diff --git a/gdb/arch/aarch64.h b/gdb/arch/aarch64.h
> index 7856d95a93b1..c9a89ac40986 100644
> --- a/gdb/arch/aarch64.h
> +++ b/gdb/arch/aarch64.h
> @@ -243,9 +243,4 @@ enum aarch64_regnum
>   /* Size of the SME2 ZT0 register in bytes.  */
>   #define AARCH64_SME2_ZT0_SIZE 64
>   
> -/* Feature check for Floating Point Mode Register.  */
> -#ifndef HWCAP2_FPMR
> -#define HWCAP2_FPMR (1ULL << 48)
> -#endif /* HWCAP2_FPMR */
> -
>   #endif /* GDB_ARCH_AARCH64_H */
> diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
> index 69aaabc1a8f9..6b61f6d5a815 100644
> --- a/gdbserver/linux-aarch64-low.cc
> +++ b/gdbserver/linux-aarch64-low.cc
> @@ -39,6 +39,7 @@
>   
>   #include "gdb_proc_service.h"
>   #include "arch/aarch64.h"
> +#include "arch/aarch64-fpmr-linux.h"
>   #include "arch/aarch64-gcs-linux.h"
>   #include "arch/aarch64-mte-linux.h"
>   #include "arch/aarch64-scalable-linux.h"

Also OK. Thanks.

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

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

[Luis]

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>

Re: [PATCH v3 4/4] GDB: aarch64-linux: Fix build failure on musl systems

[Luis]

On 17/02/2026 06:01, Thiago Jung Bauermann wrote:
> When building against musl (e.g. on Alpine Linux), the following error
> happens:
> 
>      CXX    linux-aarch64-low.o
>    In file included from /home/bauermann/src/binutils-gdb/gdbserver/linux-aarch64-low.cc:48:
>    /home/bauermann/src/binutils-gdb/gdbserver/../gdb/nat/aarch64-gcs-linux-ptrace.h:31:8: error: redefinition of 'struct user_gcs'
>       31 | struct user_gcs
>          |        ^~~~~~~~
>    In file included from /home/bauermann/src/binutils-gdb/gdbserver/linux-aarch64-low.cc:35:
>    /usr/include/asm/ptrace.h:329:8: note: previous definition of 'struct user_gcs'
>      329 | struct user_gcs {
>          |        ^~~~~~~~
>    make[2]: *** [Makefile:565: linux-aarch64-low.o] Error 1
> 
> aarch64-linux-tdep.c fails to build in the same way.  This happens
> because aarch64-linux.h uses GCS_MAGIC to see whether the system
> headers have GCS-related definitions.  The problem is that GCS_MAGIC is
> defined in <asm/sigcontext.h> while struct gcs_user is defined in
> <asm/ptrace.h>.  It's fine on glibc systems because in the set of system
> headers that linux-aarch64-low.cc and aarch64-linux-tdep.c include,
> <asm/sigcontext.h> ends up being included implicitly as well.  This
> doesn't happen when using musl's headers though.
> 
> There isn't a macro in <asm/ptrace.h> whose presence is correlated with
> the presence of the struct user_gcs definition, so a configure check is
> needed to detect it and conditionally define the struct.
> 
> Note that there's another build issue with musl, described in
> PR gdb/33747 affecting compilation of gdb/ser-unix.c.  In order to be
> able to test this patch, I applied the patch in comment 11 there.
> 
> Tested with a native build on an Alpine Linux aarch64 system, and also
> verified that all gdb.arch/aarch64-gcs*.exp tests pass on it.
> 
> Co-authored-by: Chris Packham <judge.packham@gmail.com>
> ---
> Changes since v2:
> - It's the same patch except that the header changed is
>    gdb/nat/aarch64-gcs-linux-ptrace.h rather than gdb/nat/aarch64-linux.h,
>    which doesn't exist in this version of the patch series.
> 
>   gdb/nat/aarch64-gcs-linux-ptrace.h |  5 ++---
>   gdbsupport/config.in               |  3 +++
>   gdbsupport/configure               | 36 ++++++++++++++++++++++++++++++
>   gdbsupport/configure.ac            | 19 ++++++++++++++++
>   4 files changed, 60 insertions(+), 3 deletions(-)
> 
> diff --git a/gdb/nat/aarch64-gcs-linux-ptrace.h b/gdb/nat/aarch64-gcs-linux-ptrace.h
> index f45a1059cd0a..f3dda08a1d27 100644
> --- a/gdb/nat/aarch64-gcs-linux-ptrace.h
> +++ b/gdb/nat/aarch64-gcs-linux-ptrace.h
> @@ -23,8 +23,7 @@
>   #include <stdint.h>
>   #include <asm/ptrace.h>
>   
> -/* Make sure we only define these if the kernel header doesn't.  */
> -#ifndef GCS_MAGIC
> +#ifndef HAVE_STRUCT_USER_GCS
>   
>   /* GCS state (NT_ARM_GCS).  */
>   
> @@ -35,6 +34,6 @@ struct user_gcs
>     uint64_t gcspr_el0;
>   };
>   
> -#endif /* GCS_MAGIC */
> +#endif /* HAVE_STRUCT_USER_GCS */
>   
>   #endif /* GDB_NAT_AARCH64_GCS_LINUX_PTRACE_H */
> diff --git a/gdbsupport/config.in b/gdbsupport/config.in
> index 0beacf22c057..2957ee0f0301 100644
> --- a/gdbsupport/config.in
> +++ b/gdbsupport/config.in
> @@ -271,6 +271,9 @@
>   /* Define to 1 if `st_blocks' is a member of `struct stat'. */
>   #undef HAVE_STRUCT_STAT_ST_BLOCKS
>   
> +/* Define to 1 if your system has struct user_gcs. */
> +#undef HAVE_STRUCT_USER_GCS
> +
>   /* Define to 1 if you have the <sys/param.h> header file. */
>   #undef HAVE_SYS_PARAM_H
>   
> diff --git a/gdbsupport/configure b/gdbsupport/configure
> index 05ad00f48c4f..584a80ef8255 100755
> --- a/gdbsupport/configure
> +++ b/gdbsupport/configure
> @@ -14307,6 +14307,42 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
>   
>   
>   
> +# Check for `struct user_gcs`
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for struct user_gcs" >&5
> +$as_echo_n "checking for struct user_gcs... " >&6; }
> +if ${gdb_cv_struct_user_gcs+:} false; then :
> +  $as_echo_n "(cached) " >&6
> +else
> +  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
> +/* end confdefs.h.  */
> +#include <sys/ptrace.h>
> +	 #include <asm/ptrace.h>
> +int
> +main ()
> +{
> +struct user_gcs u;
> +
> +  ;
> +  return 0;
> +}
> +_ACEOF
> +if ac_fn_c_try_compile "$LINENO"; then :
> +  gdb_cv_struct_user_gcs=yes
> +else
> +  gdb_cv_struct_user_gcs=no
> +
> +fi
> +rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
> +
> +fi
> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $gdb_cv_struct_user_gcs" >&5
> +$as_echo "$gdb_cv_struct_user_gcs" >&6; }
> +if test "$gdb_cv_struct_user_gcs" = yes; then
> +
> +$as_echo "#define HAVE_STRUCT_USER_GCS 1" >>confdefs.h
> +
> +fi
> +
>   # Set the 'development' global.
>   . $srcdir/../bfd/development.sh
>   
> diff --git a/gdbsupport/configure.ac b/gdbsupport/configure.ac
> index 5491b8f3f10a..6c06832f0913 100644
> --- a/gdbsupport/configure.ac
> +++ b/gdbsupport/configure.ac
> @@ -68,6 +68,25 @@ GDB_AC_PTRACE
>   AM_GDB_COMPILER_TYPE
>   AM_GDB_WARNINGS
>   
> +# Check for `struct user_gcs`
> +AC_CACHE_CHECK(
> +  [for struct user_gcs],
> +  [gdb_cv_struct_user_gcs],
> +  [AC_COMPILE_IFELSE(
> +     [AC_LANG_PROGRAM(
> +	[#include <sys/ptrace.h>
> +	 #include <asm/ptrace.h>],
> +	[struct user_gcs u;]
> +      )],
> +     [gdb_cv_struct_user_gcs=yes],
> +     [gdb_cv_struct_user_gcs=no]
> +  )]
> +)
> +if test "$gdb_cv_struct_user_gcs" = yes; then
> +  AC_DEFINE(HAVE_STRUCT_USER_GCS, 1,
> +	    [Define to 1 if your system has struct user_gcs.])
> +fi
> +
>   # Set the 'development' global.
>   . $srcdir/../bfd/development.sh
>   

Thanks. Still looks OK to me. I'd like a second approval from Tom or Simon.

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

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

[Simon Marchi]

>> 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

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

[Luis]

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

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

[Simon Marchi]

On 2026-02-22 05:06, Luis wrote:
> 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.
> 

This is what I was referring to, from Thiago:

    Ok. While fixing this, I noticed that gdb/arch/aarch64-gcs-linux.h also
    contains:

      /* Feature check for Guarded Control Stack.  */
      #ifndef HWCAP_GCS
      #define HWCAP_GCS (1ULL << 32)
      #endif

    which can be said to be an implicit dependency on an arch-specific
    include file (since it relies on such file defining or not HWCAP_GCS).

    Also, on non-AArch64 systems it relies on them not having by coincidence
    an unrelated hardware capability bit also named HWCAP_GCS...

    I fixed this in v2 by renaming the macro to AARCH64_HWCAP_GCS and
    defining it unconditionally (following the existing example of
    AARCH64_HWCAP_PACA).

From: https://inbox.sourceware.org/gdb-patches/87qzqkx8l1.fsf@linaro.org/T/#mbe0d3d5a2802f4f88abe907874ed44c063666639

I think that was a good idea, and it seems like we went backwards from
there?

> 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.

This is already a refactoring / cleanup series, it's not harder to do it
right from the start.

Simon

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

[Luis]

[-- Attachment #1: Type: text/plain, Size: 1840 bytes --]

That's ok by me. Would you like to clarify what Thiago needs to do so we
don't send mixed signals then?

Thanks

On Sun, Feb 22, 2026, 14:22 Simon Marchi <simark@simark.ca> wrote:

>
>
> On 2026-02-22 05:06, Luis wrote:
> > 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.
> >
>
> This is what I was referring to, from Thiago:
>
>     Ok. While fixing this, I noticed that gdb/arch/aarch64-gcs-linux.h also
>     contains:
>
>       /* Feature check for Guarded Control Stack.  */
>       #ifndef HWCAP_GCS
>       #define HWCAP_GCS (1ULL << 32)
>       #endif
>
>     which can be said to be an implicit dependency on an arch-specific
>     include file (since it relies on such file defining or not HWCAP_GCS).
>
>     Also, on non-AArch64 systems it relies on them not having by
> coincidence
>     an unrelated hardware capability bit also named HWCAP_GCS...
>
>     I fixed this in v2 by renaming the macro to AARCH64_HWCAP_GCS and
>     defining it unconditionally (following the existing example of
>     AARCH64_HWCAP_PACA).
>
> From:
> https://inbox.sourceware.org/gdb-patches/87qzqkx8l1.fsf@linaro.org/T/#mbe0d3d5a2802f4f88abe907874ed44c063666639
>
> I think that was a good idea, and it seems like we went backwards from
> there?
>
> > 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.
>
> This is already a refactoring / cleanup series, it's not harder to do it
> right from the start.
>
> Simon
>

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

[Simon Marchi]

On 2026-02-22 10:15, Luis wrote:
> That's ok by me. Would you like to clarify what Thiago needs to do so we don't send mixed signals then?

I think we can summarize it like this:

- Definitions in arch/ should be namespaced / prefixed with AARCH64_
  (e.g. AARCH64_HWCAP_FOO)
- Definitions in nat/, which are there to allow building natively
  against an older, should use the original name (e.g HWCAP_FOO)
- -tdep files should use the AARCH64_-prefixed versions (e.g.
  AARCH64_HWCAP_FOO)
- -nat (in gdb) and -low (in gdbserver) should use the original name
  (e.g. HWCAP_FOO)

Simon

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

[Thiago Jung Bauermann]

Simon Marchi <simark@simark.ca> writes:

> On 2026-02-22 10:15, Luis wrote:
>> That's ok by me. Would you like to clarify what Thiago needs to do so we don't send mixed signals then?
>
> I think we can summarize it like this:
>
> - Definitions in arch/ should be namespaced / prefixed with AARCH64_
>   (e.g. AARCH64_HWCAP_FOO)
> - Definitions in nat/, which are there to allow building natively
>   against an older, should use the original name (e.g HWCAP_FOO)
> - -tdep files should use the AARCH64_-prefixed versions (e.g.
>   AARCH64_HWCAP_FOO)
> - -nat (in gdb) and -low (in gdbserver) should use the original name
>   (e.g. HWCAP_FOO)

Thank you for the clarification. I've done all of the above in v4.

Regarding the first point, I found some definitions in arch/ besides the
HWCAP ones which should have the AARCH64_ prefix, so I did that too:

- SEGV_MTEAERR → AARCH64_SEGV_MTEAERR
- SEGV_MTESERR → AARCH64_SEGV_MTESERR
- SEGV_CPERR → AARCH64_SEGV_CPERR
- PR_SHADOW_STACK_ENABLE → AARCH64_PR_SHADOW_STACK_ENABLE
- PR_SHADOW_STACK_WRITE → AARCH64_PR_SHADOW_STACK_WRITE
- PR_SHADOW_STACK_PUSH → AARCH64_PR_SHADOW_STACK_PUSH

Actually, the last four of them weren't even in a gdb/arch/ header, but
in gdb/linux-tdep.h. I moved them into gdb/arch/.

From your other email in this thread:

> On 2026-02-22 05:06, Luis wrote:
>> 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.
>> 
>
> This is what I was referring to, from Thiago:
>
>     Ok. While fixing this, I noticed that gdb/arch/aarch64-gcs-linux.h also
>     contains:
>
>       /* Feature check for Guarded Control Stack.  */
>       #ifndef HWCAP_GCS
>       #define HWCAP_GCS (1ULL << 32)
>       #endif
>
>     which can be said to be an implicit dependency on an arch-specific
>     include file (since it relies on such file defining or not HWCAP_GCS).
>
>     Also, on non-AArch64 systems it relies on them not having by coincidence
>     an unrelated hardware capability bit also named HWCAP_GCS...
>
>     I fixed this in v2 by renaming the macro to AARCH64_HWCAP_GCS and
>     defining it unconditionally (following the existing example of
>     AARCH64_HWCAP_PACA).
>
> From: https://inbox.sourceware.org/gdb-patches/87qzqkx8l1.fsf@linaro.org/T/#mbe0d3d5a2802f4f88abe907874ed44c063666639
>
> I think that was a good idea, and it seems like we went backwards from
> there?

I misunderstood this comment you made when you reviewed v2¹:

>> diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
>> index 028de981588b..b2dd192a7b56 100644
>> --- a/gdb/aarch64-linux-nat.c
>> +++ b/gdb/aarch64-linux-nat.c
>> @@ -51,7 +51,7 @@
>>  #include "gdb_proc_service.h"
>>  #include "arch-utils.h"
>>  
>> -#include "arch/aarch64-gcs-linux.h"
>> +#include "arch/aarch64-linux.h"
>>  #include "arch/aarch64-mte-linux.h"
>>  
>>  #include "nat/aarch64-mte-linux-ptrace.h"
>> @@ -1013,7 +1013,7 @@ aarch64_linux_nat_target::read_description ()
>>       active or not.  */
>>    features.vq = aarch64_sve_get_vq (tid);
>>    features.pauth = hwcap & AARCH64_HWCAP_PACA;
>> -  features.gcs = features.gcs_linux = hwcap & HWCAP_GCS;
>
> This one could stay HWCAP_GCS, but I don't have a preference.
>
> If we want to ensure / prove they are the same, we could add asserts
> like this in the nat/ header:
>
>   static_assert (AARCH64_HWCAP_GCS == HWCAP_GCS);
>
> That assert would only be checked when compiling natively for an aarch64
> system (where HWCAP_GCS is available), but it's better than nothing.

to mean that you didn't have a preference on whether to use
AARCH64_-prefixed definitions. I didn't notice that the comment was made
in a hunk from a -nat.c file. Sorry for the confusion.

-- 
Thiago

¹ https://inbox.sourceware.org/gdb-patches/5cebfbfa-a192-4359-97d9-83455d40fdc6@simark.ca/