[PATCH v4 2/6] GDB: Add aarch64-fpmr-linux.h to gdb/arch/ and gdb/nat/

Thiago Jung Bauermann
2026-03-03T05:07:43Z

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 new Linux- and feature-specific headers to contain it, one for
target-dependent code and the other for native code.

The target-dependant code should use AARCH64_HWCAP2_FPRM in
gdb/arch/aarch64-pauth-linux.h while native code should use HWCAP2_FPRM,
which will hopefully be defined by the system headers but with a backup
definition in gdb/nat/aarch64-pauth-linux.h if it isn't.

Suggested-by: Luis <luis.machado.foss@gmail.com>
Suggested-by: Simon Marchi <simark@simark.ca>
---
Changes since v3:
- Also create gdb/nat/aarch64-fpmr-linux.h header.
- Add AARCH64_HWCAP2_FPMR and use it in gdb/aarch64-linux-tdep.c.

gdb/Makefile.in | 2 ++
gdb/aarch64-linux-nat.c | 1 +
gdb/aarch64-linux-tdep.c | 3 ++-
gdb/arch/aarch64-fpmr-linux.h | 26 ++++++++++++++++++++++++++
gdb/arch/aarch64.h | 5 -----
gdb/nat/aarch64-fpmr-linux.h | 28 ++++++++++++++++++++++++++++
gdbserver/linux-aarch64-low.cc | 1 +
7 files changed, 60 insertions(+), 6 deletions(-)
create mode 100644 gdb/arch/aarch64-fpmr-linux.h
create mode 100644 gdb/nat/aarch64-fpmr-linux.h

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index a412f3b3c592..3d9bc86a97fd 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 \
@@ -1546,6 +1547,7 @@ HFILES_NO_SRCDIR = \
mn10300-tdep.h \
moxie-tdep.h \
namespace.h \
+ nat/aarch64-fpmr-linux.h \
nat/aarch64-hw-point.h \
nat/aarch64-linux.h \
nat/aarch64-linux-hw-point.h \
diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index f64cc0a97d88..81a46ee1f0d0 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -32,6 +32,7 @@
#include "aarch32-linux-nat.h"
#include "aarch32-tdep.h"
#include "arch/arm.h"
+#include "nat/aarch64-fpmr-linux.h"
#include "nat/aarch64-linux.h"
#include "nat/aarch64-linux-hw-point.h"
#include "nat/aarch64-pauth-linux.h"
diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index d3d4c9e1de38..504e4126f1bc 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"
@@ -1764,7 +1765,7 @@ aarch64_linux_core_read_description (struct gdbarch *gdbarch,
features.pauth = hwcap & AARCH64_HWCAP_PACA;
features.gcs = features.gcs_linux = hwcap & HWCAP_GCS;
features.mte = hwcap2 & HWCAP2_MTE;
- features.fpmr = hwcap2 & HWCAP2_FPMR;
+ features.fpmr = hwcap2 & AARCH64_HWCAP2_FPMR;

/* Handle the TLS section. */
asection *tls = bfd_get_section_by_name (abfd, ".reg-aarch-tls");
diff --git a/gdb/arch/aarch64-fpmr-linux.h b/gdb/arch/aarch64-fpmr-linux.h
new file mode 100644
index 000000000000..5495cf8c0018
--- /dev/null
+++ b/gdb/arch/aarch64-fpmr-linux.h
@@ -0,0 +1,26 @@
+/* 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. */
+#define AARCH64_HWCAP2_FPMR (1ULL << 48)
+
+#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/gdb/nat/aarch64-fpmr-linux.h b/gdb/nat/aarch64-fpmr-linux.h
new file mode 100644
index 000000000000..bb0243a89396
--- /dev/null
+++ b/gdb/nat/aarch64-fpmr-linux.h
@@ -0,0 +1,28 @@
+/* Common Linux native 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_NAT_AARCH64_FPMR_LINUX_H
+#define GDB_NAT_AARCH64_FPMR_LINUX_H
+
+/* Feature check for Floating Point Mode Register. */
+#ifndef HWCAP2_FPMR
+#define HWCAP2_FPMR (1ULL << 48)
+#endif /* HWCAP2_FPMR */
+
+#endif /* GDB_NAT_AARCH64_FPMR_LINUX_H */
diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
index 07ddfb324466..a6439943e855 100644
--- a/gdbserver/linux-aarch64-low.cc
+++ b/gdbserver/linux-aarch64-low.cc
@@ -46,6 +46,7 @@
#include "arch/aarch64-scalable-linux.h"
#include "linux-aarch32-tdesc.h"
#include "linux-aarch64-tdesc.h"
+#include "nat/aarch64-fpmr-linux.h"
#include "nat/aarch64-mte-linux-ptrace.h"
#include "nat/aarch64-scalable-linux-ptrace.h"
#include "tdesc.h"