[PATCH v4 3/6] GDB: aarch64-linux: Reorganize MTE-related definitions

Thiago Jung Bauermann
2026-03-03T05:07:56Z

GDB conditionally defines HWCAP2_MTE in gdb/arch/aarch64-mte-linux.h, but
that's not the best place for it since it's a definition that should be
used only in native code so move it to gdb/nat/aarch64-mte-linux-ptrace.h.

Introduce an AARCH64_HWCAP2_MTE in gdb/arch/aarch64-mte-linux.h to be used
by target-dependant code.

Similarly, add AARCH64_ prefix to the SEGV_MTEAERR and SEGV_MTESERR
definitions in gdb/arch/aarch64-mte-linux.h.

I noticed that enum class aarch64_memtag_type is only used in native code,
so move its definition to gdb/nat/aarch64-mte-linux-ptrace.h as well.

I also noticed that gdb/aarch64-linux-tdep.h defines
AARCH64_LINUX_SIZEOF_MTE_REGSET which is redundant with
AARCH64_LINUX_SIZEOF_MTE, already defined in gdb/arch/aarch64-mte-linux.h
so consolidate both definitions.

Finally, the include of arch/aarch64-mte-linux.h isn't used in
gdb/aarch64-linux-nat.c nor in gdb/nat/aarch64-mte-linux-ptrace.c so
remove it from them.

Suggested-by: Luis <luis.machado.foss@gmail.com>
Suggested-by: Simon Marchi <simark@simark.ca>
---
gdb/aarch64-linux-nat.c | 4 +---
gdb/aarch64-linux-tdep.c | 6 +++---
gdb/aarch64-linux-tdep.h | 3 ---
gdb/arch/aarch64-mte-linux.h | 23 ++++-------------------
gdb/nat/aarch64-mte-linux-ptrace.c | 1 -
gdb/nat/aarch64-mte-linux-ptrace.h | 14 ++++++++++++++
gdbserver/linux-aarch64-low.cc | 2 +-
7 files changed, 23 insertions(+), 30 deletions(-)

diff --git a/gdb/aarch64-linux-nat.c b/gdb/aarch64-linux-nat.c
index 81a46ee1f0d0..d12e2ddcfb28 100644
--- a/gdb/aarch64-linux-nat.c
+++ b/gdb/aarch64-linux-nat.c
@@ -35,6 +35,7 @@
#include "nat/aarch64-fpmr-linux.h"
#include "nat/aarch64-linux.h"
#include "nat/aarch64-linux-hw-point.h"
+#include "nat/aarch64-mte-linux-ptrace.h"
#include "nat/aarch64-pauth-linux.h"
#include "nat/aarch64-scalable-linux-ptrace.h"

@@ -54,9 +55,6 @@
#include "arch-utils.h"

#include "arch/aarch64-gcs-linux.h"
-#include "arch/aarch64-mte-linux.h"
-
-#include "nat/aarch64-mte-linux-ptrace.h"
#include "arch/aarch64-scalable-linux.h"

#include <string.h>
diff --git a/gdb/aarch64-linux-tdep.c b/gdb/aarch64-linux-tdep.c
index 504e4126f1bc..4ca05fba771d 100644
--- a/gdb/aarch64-linux-tdep.c
+++ b/gdb/aarch64-linux-tdep.c
@@ -1764,7 +1764,7 @@ aarch64_linux_core_read_description (struct gdbarch *gdbarch,
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.mte = hwcap2 & HWCAP2_MTE;
+ features.mte = hwcap2 & AARCH64_HWCAP2_MTE;
features.fpmr = hwcap2 & AARCH64_HWCAP2_FPMR;

/* Handle the TLS section. */
@@ -2698,7 +2698,7 @@ aarch64_linux_report_signal_info (struct gdbarch *gdbarch,

const char *meaning;

- if (si_code == SEGV_MTEAERR || si_code == SEGV_MTESERR)
+ if (si_code == AARCH64_SEGV_MTEAERR || si_code == AARCH64_SEGV_MTESERR)
meaning = _("Memory tag violation");
else if (si_code == SEGV_CPERR && si_errno == 0)
meaning = _("Guarded Control Stack error");
@@ -2710,7 +2710,7 @@ aarch64_linux_report_signal_info (struct gdbarch *gdbarch,
uiout->field_string ("sigcode-meaning", meaning);

/* For synchronous faults, show additional information. */
- if (si_code == SEGV_MTESERR)
+ if (si_code == AARCH64_SEGV_MTESERR)
{
uiout->text (_(" while accessing address "));
uiout->field_core_addr ("fault-addr", gdbarch, fault_addr);
diff --git a/gdb/aarch64-linux-tdep.h b/gdb/aarch64-linux-tdep.h
index b99fe91f36bd..385b03cc1be7 100644
--- a/gdb/aarch64-linux-tdep.h
+++ b/gdb/aarch64-linux-tdep.h
@@ -33,9 +33,6 @@
alignment. */
#define AARCH64_LINUX_SIZEOF_FPREGSET (33 * V_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;

diff --git a/gdb/arch/aarch64-mte-linux.h b/gdb/arch/aarch64-mte-linux.h
index 5c7e78c71eaf..bc31ae52b916 100644
--- a/gdb/arch/aarch64-mte-linux.h
+++ b/gdb/arch/aarch64-mte-linux.h
@@ -20,29 +20,14 @@
#ifndef GDB_ARCH_AARCH64_MTE_LINUX_H
#define GDB_ARCH_AARCH64_MTE_LINUX_H

-
-/* Feature check for Memory Tagging Extension. */
-#ifndef HWCAP2_MTE
-#define HWCAP2_MTE (1 << 18)
-#endif
+#define AARCH64_HWCAP2_MTE (1 << 18)

/* The MTE regset consists of a single 64-bit register. */
-#define AARCH64_LINUX_SIZEOF_MTE 8
+#define AARCH64_LINUX_SIZEOF_MTE_REGSET 8

/* Memory tagging definitions. */
-#ifndef SEGV_MTEAERR
-# define SEGV_MTEAERR 8
-# define SEGV_MTESERR 9
-#endif
-
-/* Memory tag types for AArch64. */
-enum class aarch64_memtag_type
-{
- /* MTE logical tag contained in pointers. */
- mte_logical = 0,
- /* MTE allocation tag stored in memory tag granules. */
- mte_allocation
-};
+#define AARCH64_SEGV_MTEAERR 8
+#define AARCH64_SEGV_MTESERR 9

/* Given a TAGS vector containing 1 MTE tag per byte, pack the data as
2 tags per byte and resize the vector. */
diff --git a/gdb/nat/aarch64-mte-linux-ptrace.c b/gdb/nat/aarch64-mte-linux-ptrace.c
index 903e11841201..c88b1d4fcd23 100644
--- a/gdb/nat/aarch64-mte-linux-ptrace.c
+++ b/gdb/nat/aarch64-mte-linux-ptrace.c
@@ -23,7 +23,6 @@

#include "arch/aarch64.h"
#include "arch/aarch64-mte.h"
-#include "arch/aarch64-mte-linux.h"
#include "nat/aarch64-linux.h"
#include "nat/aarch64-mte-linux-ptrace.h"

diff --git a/gdb/nat/aarch64-mte-linux-ptrace.h b/gdb/nat/aarch64-mte-linux-ptrace.h
index d31fa9f3c071..653de33108c8 100644
--- a/gdb/nat/aarch64-mte-linux-ptrace.h
+++ b/gdb/nat/aarch64-mte-linux-ptrace.h
@@ -20,6 +20,11 @@
#ifndef GDB_NAT_AARCH64_MTE_LINUX_PTRACE_H
#define GDB_NAT_AARCH64_MTE_LINUX_PTRACE_H

+/* Feature check for Memory Tagging Extension. */
+#ifndef HWCAP2_MTE
+#define HWCAP2_MTE (1 << 18)
+#endif
+
/* MTE allocation tag access */

#ifndef PTRACE_PEEKMTETAGS
@@ -33,6 +38,15 @@
/* Maximum number of tags to pass at once to the kernel. */
#define AARCH64_MTE_TAGS_MAX_SIZE 4096

+/* Memory tag types for AArch64. */
+enum class aarch64_memtag_type
+{
+ /* MTE logical tag contained in pointers. */
+ mte_logical = 0,
+ /* MTE allocation tag stored in memory tag granules. */
+ mte_allocation
+};
+
/* Read the allocation tags from memory range [ADDRESS, ADDRESS + LEN)
into TAGS.

diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
index a6439943e855..a00ee1556c80 100644
--- a/gdbserver/linux-aarch64-low.cc
+++ b/gdbserver/linux-aarch64-low.cc
@@ -959,7 +959,7 @@ aarch64_adjust_register_sets (const struct aarch64_features &features)
break;
case NT_ARM_TAGGED_ADDR_CTRL:
if (features.mte)
- regset->size = AARCH64_LINUX_SIZEOF_MTE;
+ regset->size = AARCH64_LINUX_SIZEOF_MTE_REGSET;
break;
case NT_ARM_TLS:
if (features.tls > 0)