New target methods for memory tagging support

This patch starts adding some of the generic pieces to accomodate memory
tagging.

We have three new target methods:

- supports_memory_tagging: Checks if the target supports memory tagging. This
  defaults to false for targets that don't support memory tagging.

- fetch_memtags: Fetches the allocation tags associated with a particular
  memory range [address, address + length).

  The default is to return 0 without returning any tags. This should only
  be called if memory tagging is supported.

- store_memtags: Stores a set of allocation tags for a particular memory
  range [address, address + length).

  The default is to return 0. This should only
  be called if memory tagging is supported.

gdb/ChangeLog:

2021-03-24  Luis Machado  <luis.machado@linaro.org>

	* remote.c (remote_target) <supports_memory_tagging>: New method
	override.
	<fetch_memtags>: New method override.
	<store_memtags>: New method override.
	(remote_target::supports_memory_tagging): New method.
	(remote_target::fetch_memtags): New method.
	(remote_target::store_memtags): New method.
	* target-delegates.c: Regenerate.
	* target.h (struct target_ops) <supports_memory_tagging>: New virtual
	method.
	<fetch_memtags>: New virtual method.
	<store_memtags>: New virtual method.
	(target_supports_memory_tagging): Define.
	(target_fetch_memtags): Define.
	(target_store_memtags): Define.
	* target-debug.h (target_debug_print_size_t)
	(target_debug_print_const_gdb_byte_vector_r)
	(target_debug_print_gdb_byte_vector_r): New functions.

1 files changed, 95 insertions, 0 deletions

diff --git a/gdb/target-delegates.c b/gdb/target-delegates.c
index 1c79997..74103bf 100644
--- a/gdb/target-delegates.c
+++ b/gdb/target-delegates.c
@@ -173,6 +173,9 @@ struct dummy_target : public target_ops
   const struct frame_unwind *get_tailcall_unwinder () override;
   void prepare_to_generate_core () override;
   void done_generating_core () override;
+  bool supports_memory_tagging () override;
+  bool fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3) override;
+  bool store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3) override;
 };
 
 struct debug_target : public target_ops
@@ -344,6 +347,9 @@ struct debug_target : public target_ops
   const struct frame_unwind *get_tailcall_unwinder () override;
   void prepare_to_generate_core () override;
   void done_generating_core () override;
+  bool supports_memory_tagging () override;
+  bool fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3) override;
+  bool store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3) override;
 };
 
 void
@@ -4413,3 +4419,92 @@ debug_target::done_generating_core ()
   fputs_unfiltered (")\n", gdb_stdlog);
 }
 
+bool
+target_ops::supports_memory_tagging ()
+{
+  return this->beneath ()->supports_memory_tagging ();
+}
+
+bool
+dummy_target::supports_memory_tagging ()
+{
+  return false;
+}
+
+bool
+debug_target::supports_memory_tagging ()
+{
+  bool result;
+  fprintf_unfiltered (gdb_stdlog, "-> %s->supports_memory_tagging (...)\n", this->beneath ()->shortname ());
+  result = this->beneath ()->supports_memory_tagging ();
+  fprintf_unfiltered (gdb_stdlog, "<- %s->supports_memory_tagging (", this->beneath ()->shortname ());
+  fputs_unfiltered (") = ", gdb_stdlog);
+  target_debug_print_bool (result);
+  fputs_unfiltered ("\n", gdb_stdlog);
+  return result;
+}
+
+bool
+target_ops::fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3)
+{
+  return this->beneath ()->fetch_memtags (arg0, arg1, arg2, arg3);
+}
+
+bool
+dummy_target::fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3)
+{
+  tcomplain ();
+}
+
+bool
+debug_target::fetch_memtags (CORE_ADDR arg0, size_t arg1, gdb::byte_vector &arg2, int arg3)
+{
+  bool result;
+  fprintf_unfiltered (gdb_stdlog, "-> %s->fetch_memtags (...)\n", this->beneath ()->shortname ());
+  result = this->beneath ()->fetch_memtags (arg0, arg1, arg2, arg3);
+  fprintf_unfiltered (gdb_stdlog, "<- %s->fetch_memtags (", this->beneath ()->shortname ());
+  target_debug_print_CORE_ADDR (arg0);
+  fputs_unfiltered (", ", gdb_stdlog);
+  target_debug_print_size_t (arg1);
+  fputs_unfiltered (", ", gdb_stdlog);
+  target_debug_print_gdb_byte_vector_r (arg2);
+  fputs_unfiltered (", ", gdb_stdlog);
+  target_debug_print_int (arg3);
+  fputs_unfiltered (") = ", gdb_stdlog);
+  target_debug_print_bool (result);
+  fputs_unfiltered ("\n", gdb_stdlog);
+  return result;
+}
+
+bool
+target_ops::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3)
+{
+  return this->beneath ()->store_memtags (arg0, arg1, arg2, arg3);
+}
+
+bool
+dummy_target::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3)
+{
+  tcomplain ();
+}
+
+bool
+debug_target::store_memtags (CORE_ADDR arg0, size_t arg1, const gdb::byte_vector &arg2, int arg3)
+{
+  bool result;
+  fprintf_unfiltered (gdb_stdlog, "-> %s->store_memtags (...)\n", this->beneath ()->shortname ());
+  result = this->beneath ()->store_memtags (arg0, arg1, arg2, arg3);
+  fprintf_unfiltered (gdb_stdlog, "<- %s->store_memtags (", this->beneath ()->shortname ());
+  target_debug_print_CORE_ADDR (arg0);
+  fputs_unfiltered (", ", gdb_stdlog);
+  target_debug_print_size_t (arg1);
+  fputs_unfiltered (", ", gdb_stdlog);
+  target_debug_print_const_gdb_byte_vector_r (arg2);
+  fputs_unfiltered (", ", gdb_stdlog);
+  target_debug_print_int (arg3);
+  fputs_unfiltered (") = ", gdb_stdlog);
+  target_debug_print_bool (result);
+  fputs_unfiltered ("\n", gdb_stdlog);
+  return result;
+}
+