[PATCH v2 1/2] GDB: aarch64-linux: Reorganize gdb/arch/aarch64-gcs-linux.h

[Thiago Jung Bauermann <thiago.bauermann@linaro.org>]

This file implicitly depends on aarch64-linux's <asm/sigcontext.h> for
the definition of GCS_MAGIC and on its <bits/hwcap.h> for the definition
of HWCAP_GCS, but files on gdb/arch/ shouldn't depend on include files
specific to the architecture.

Regarding GCS_MAGIC and struct user_gcs, move that code section to
gdb/nat/aarch64-linux.h which can rely on <asm/sigcontext.h> and
<asm/ptrace.h>.

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 aarch64-linux-tdep.h and use it
in aarch64-linux-tdep.c, as is done for other regsets and following a
suggestion from Simon Marchi.

Regarding HWCAP_GCS, rename it to AARCH64_HWCAP_GCS to ensure that it
won't conflict with any system header definition and define it
unconditionally, following the example of AARCH64_HWCAP_PACA.

Renaming HWCAP_GCS also avoids a potential (and I would say unlikely)
problem on non-AArch64 systems: naming conflict if by coincidence they have
an unrelated hardware capability bit also named HWCAP_GCS.

Finally, I noticed that AARCH64_HWCAP_PACA is duplicated in GDB and
gdbserver files, so consolidate them in the same header and rename it to
gdb/arch/aarch64-linux.h since it isn't just about GCS anymore.
---

As I mentioned on v1's email thread, this patch opens a small can of worms,
since other gdb/arch/aarch64*.h do the same kind of thing (mostly with
HWCAP macros but also a few others).

Perhaps I'm going too far with the HWCAP_GCS renaming and the current
handling of it is fine?

 gdb/Makefile.in                               |  2 +-
 gdb/aarch64-linux-nat.c                       |  4 +--
 gdb/aarch64-linux-tdep.c                      |  9 +++---
 gdb/aarch64-linux-tdep.h                      |  6 ++--
 .../{aarch64-gcs-linux.h => aarch64-linux.h}  | 30 +++++--------------
 gdb/nat/aarch64-linux.h                       | 16 ++++++++++
 gdbserver/linux-aarch64-low.cc                |  7 ++---
 7 files changed, 36 insertions(+), 38 deletions(-)
 rename gdb/arch/{aarch64-gcs-linux.h => aarch64-linux.h} (61%)

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 2aa95be968ac..fd47c613966a 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1301,7 +1301,7 @@ HFILES_NO_SRCDIR = \
 	amdgpu-tdep.h \
 	annotate.h \
 	arch/aarch32.h \
-	arch/aarch64-gcs-linux.h \
+	arch/aarch64-linux.h \
 	arch/aarch64.h \
 	arch/aarch64-insn.h \
 	arch/aarch64-mte.h \
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;
+  features.gcs = features.gcs_linux = hwcap & AARCH64_HWCAP_GCS;
   features.mte = hwcap2 & HWCAP2_MTE;
   features.tls = aarch64_tls_register_count (tid);
   /* SME feature check.  */
diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index b85c25ecae1d..33e1b411ff1d 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -51,7 +51,7 @@
 #include "record-full.h"
 #include "linux-record.h"
 
-#include "arch/aarch64-gcs-linux.h"
+#include "arch/aarch64-linux.h"
 #include "arch/aarch64-mte.h"
 #include "arch/aarch64-mte-linux.h"
 #include "arch/aarch64-scalable-linux.h"
@@ -1734,8 +1734,9 @@ 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);
     }
 }
 
@@ -1761,7 +1762,7 @@ aarch64_linux_core_read_description (struct gdbarch *gdbarch,
      length.  */
   features.vq = aarch64_linux_core_read_vq_from_sections (gdbarch, abfd);
   features.pauth = hwcap & AARCH64_HWCAP_PACA;
-  features.gcs = features.gcs_linux = hwcap & HWCAP_GCS;
+  features.gcs = features.gcs_linux = hwcap & AARCH64_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..f247d6aa72cd 100644
--- a/gdb/aarch64-linux-tdep.h
+++ b/gdb/aarch64-linux-tdep.h
@@ -39,10 +39,10 @@
 /* The MTE regset consists of a 64-bit register.  */
 #define AARCH64_LINUX_SIZEOF_MTE_REGSET (8)
 
+/* The GCS regset consists of 3 64-bit registers.  */
+#define AARCH64_LINUX_SIZEOF_GCS_REGSET (3 * 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-gcs-linux.h b/gdb/arch/aarch64-linux.h
similarity index 61%
rename from gdb/arch/aarch64-gcs-linux.h
rename to gdb/arch/aarch64-linux.h
index b31fc32daa03..a33c082a0318 100644
--- a/gdb/arch/aarch64-gcs-linux.h
+++ b/gdb/arch/aarch64-linux.h
@@ -1,4 +1,4 @@
-/* Common Linux target-dependent definitions for AArch64 GCS
+/* Common Linux target-dependent definitions for AArch64 running Linux.
 
    Copyright (C) 2025-2026 Free Software Foundation, Inc.
 
@@ -17,28 +17,12 @@
    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_GCS_LINUX_H
-#define GDB_ARCH_AARCH64_GCS_LINUX_H
-
-#include <stdint.h>
+#ifndef GDB_ARCH_AARCH64_LINUX_H
+#define GDB_ARCH_AARCH64_LINUX_H
 
+/* Matches HWCAP_PACA in kernel header arch/arm64/include/uapi/asm/hwcap.h.  */
+#define AARCH64_HWCAP_PACA (1 << 30)
 /* 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 */
+#define AARCH64_HWCAP_GCS (1ULL << 32)
 
-#endif /* GDB_ARCH_AARCH64_GCS_LINUX_H */
+#endif /* GDB_ARCH_AARCH64_LINUX_H */
diff --git a/gdb/nat/aarch64-linux.h b/gdb/nat/aarch64-linux.h
index bb5381eba3ef..f7c09aa112bf 100644
--- a/gdb/nat/aarch64-linux.h
+++ b/gdb/nat/aarch64-linux.h
@@ -19,7 +19,9 @@
 #ifndef GDB_NAT_AARCH64_LINUX_H
 #define GDB_NAT_AARCH64_LINUX_H
 
+#include <stdint.h>
 #include <signal.h>
+#include <asm/ptrace.h>
 
 /* Defines ps_err_e, struct ps_prochandle.  */
 #include "gdb_proc_service.h"
@@ -113,6 +115,20 @@ typedef struct compat_siginfo
 #define cpt_si_band _sifields._sigpoll._band
 #define cpt_si_fd _sifields._sigpoll._fd
 
+/* 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 */
+
 void aarch64_siginfo_from_compat_siginfo (siginfo_t *to,
 					    compat_siginfo_t *from);
 void aarch64_compat_siginfo_from_siginfo (compat_siginfo_t *to,
diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
index b19e605f55d6..60ea50f609cc 100644
--- a/gdbserver/linux-aarch64-low.cc
+++ b/gdbserver/linux-aarch64-low.cc
@@ -39,7 +39,7 @@
 
 #include "gdb_proc_service.h"
 #include "arch/aarch64.h"
-#include "arch/aarch64-gcs-linux.h"
+#include "arch/aarch64-linux.h"
 #include "arch/aarch64-mte-linux.h"
 #include "arch/aarch64-scalable-linux.h"
 #include "linux-aarch32-tdesc.h"
@@ -984,9 +984,6 @@ 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
@@ -1009,7 +1006,7 @@ aarch64_target::low_arch_setup ()
       /* A-profile MTE is 64-bit only.  */
       features.mte = linux_get_hwcap2 (pid, 8) & HWCAP2_MTE;
       features.tls = aarch64_tls_register_count (tid);
-      features.gcs = features.gcs_linux = linux_get_hwcap (pid, 8) & HWCAP_GCS;
+      features.gcs = features.gcs_linux = linux_get_hwcap (pid, 8) & AARCH64_HWCAP_GCS;
       features.fpmr = linux_get_hwcap2 (pid, 8) & HWCAP2_FPMR;
 
       /* Scalable Matrix Extension feature and size check.  */