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

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

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);