[PATCH 17/23] AArch64: Add gdbserver MTE support

[Luis Machado <luis.machado@linaro.org>]

Adds the AArch64-specific memory tagging support (MTE) by implementing the
required hooks and checks for GDBserver.

gdbserver/ChangeLog:

YYYY-MM-DD  Luis Machado  <luis.machado@linaro.org>

	* Makefile.in (SFILES): Add /../gdb/nat/aarch64-mte-linux-ptrace.c.
	* configure.srv (aarch64*-*-linux*): Add arch/aarch64-mte-linux.o and
	nat/aarch64-mte-linux-ptrace.o.
	* linux-aarch64-low.cc: Include nat/aarch64-mte-linux-ptrace.h.
	(class aarch64_target) <supports_memory_tagging>
	<fetch_memtags, store_memtags>: New method overrides.
	(aarch64_target::supports_memory_tagging)
	(aarch64_target::fetch_memtags)
	(aarch64_target::store_memtags): New methods.
---
 gdbserver/Makefile.in          |  1 +
 gdbserver/configure.srv        |  2 ++
 gdbserver/linux-aarch64-low.cc | 53 ++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

diff --git a/gdbserver/Makefile.in b/gdbserver/Makefile.in
index 9d7687be53..8e54e1fd09 100644
--- a/gdbserver/Makefile.in
+++ b/gdbserver/Makefile.in
@@ -212,6 +212,7 @@ SFILES = \
 	$(srcdir)/../gdb/arch/ppc-linux-common.c \
 	$(srcdir)/../gdb/arch/riscv.c \
 	$(srcdir)/../gdb/nat/aarch64-sve-linux-ptrace.c \
+	$(srcdir)/../gdb/nat/aarch64-mte-linux-ptrace.c \
 	$(srcdir)/../gdb/nat/linux-btrace.c \
 	$(srcdir)/../gdb/nat/linux-namespaces.c \
 	$(srcdir)/../gdb/nat/linux-osdata.c \
diff --git a/gdbserver/configure.srv b/gdbserver/configure.srv
index 5e33bd9c54..e8d599e866 100644
--- a/gdbserver/configure.srv
+++ b/gdbserver/configure.srv
@@ -52,8 +52,10 @@ case "${gdbserver_host}" in
 			srv_tgtobj="$srv_tgtobj nat/aarch64-linux.o"
 			srv_tgtobj="$srv_tgtobj arch/aarch64-insn.o"
 			srv_tgtobj="$srv_tgtobj arch/aarch64.o"
+			srv_tgtobj="$srv_tgtobj arch/aarch64-mte-linux.o"
 			srv_tgtobj="$srv_tgtobj linux-aarch64-tdesc.o"
 			srv_tgtobj="$srv_tgtobj nat/aarch64-sve-linux-ptrace.o"
+			srv_tgtobj="$srv_tgtobj nat/aarch64-mte-linux-ptrace.o"
 			srv_tgtobj="${srv_tgtobj} $srv_linux_obj"
 			srv_linux_regsets=yes
 			srv_linux_thread_db=yes
diff --git a/gdbserver/linux-aarch64-low.cc b/gdbserver/linux-aarch64-low.cc
index 22485d9466..f8d2511fff 100644
--- a/gdbserver/linux-aarch64-low.cc
+++ b/gdbserver/linux-aarch64-low.cc
@@ -44,12 +44,17 @@
 #include "linux-aarch32-tdesc.h"
 #include "linux-aarch64-tdesc.h"
 #include "nat/aarch64-sve-linux-ptrace.h"
+#include "nat/aarch64-mte-linux-ptrace.h"
 #include "tdesc.h"
 
 #ifdef HAVE_SYS_REG_H
 #include <sys/reg.h>
 #endif
 
+#ifdef HAVE_GETAUXVAL
+#include <sys/auxv.h>
+#endif
+
 /* Linux target op definitions for the AArch64 architecture.  */
 
 class aarch64_target : public linux_process_target
@@ -82,6 +87,14 @@ public:
 
   struct emit_ops *emit_ops () override;
 
+  bool supports_memory_tagging () override;
+
+  int fetch_memtags (CORE_ADDR address, size_t len,
+		     gdb::byte_vector &tags) override;
+
+  int store_memtags (CORE_ADDR address, size_t len,
+		     const gdb::byte_vector &tags) override;
+
 protected:
 
   void low_arch_setup () override;
@@ -3201,6 +3214,46 @@ aarch64_target::breakpoint_kind_from_current_state (CORE_ADDR *pcptr)
     return arm_breakpoint_kind_from_current_state (pcptr);
 }
 
+/* Returns true if memory tagging is supported.  */
+bool
+aarch64_target::supports_memory_tagging ()
+{
+  if (current_thread == NULL)
+    {
+      /* We don't have any processes running, so don't attempt to
+	 use linux_get_hwcap2 as it will try to fetch the current
+	 thread id.  Instead, just fetch the auxv from the self
+	 PID.  */
+#ifdef HAVE_GETAUXVAL
+      return (getauxval (AT_HWCAP2) & HWCAP2_MTE) != 0;
+#else
+      return true;
+#endif
+    }
+
+  return (linux_get_hwcap2 (8) & HWCAP2_MTE) != 0;
+}
+
+int
+aarch64_target::fetch_memtags (CORE_ADDR address, size_t len,
+			       gdb::byte_vector &tags)
+{
+  /* Allocation tags are per-process, so any tid is fine.  */
+  int tid = lwpid_of (current_thread);
+
+  return aarch64_mte_fetch_memtags (tid, address, len, tags);
+}
+
+int
+aarch64_target::store_memtags (CORE_ADDR address, size_t len,
+			       const gdb::byte_vector &tags)
+{
+  /* Allocation tags are per-process, so any tid is fine.  */
+  int tid = lwpid_of (current_thread);
+
+  return aarch64_mte_store_memtags (tid, address, len, tags);
+}
+
 /* The linux target ops object.  */
 
 linux_process_target *the_linux_target = &the_aarch64_target;
-- 
2.17.1