GDBserver remote packet support for memory tagging

This patch adds the generic remote bits to gdbserver so it can check for memory
tagging support and handle fetch tags and store tags requests.

gdbserver/ChangeLog:

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

	* remote-utils.cc (decode_m_packet_params): Renamed from ...
	(decode_m_packet): ... this, which now calls decode_m_packet_params.
	Make char * param/return const char *.
	(decode_M_packet): Use decode_m_packet_params and make char * param
	const char *.
	* remote-utils.h (decode_m_packet_params): New prototype.
	(decode_m_packet): Constify char pointers.
	(decode_M_packet): Likewise.
	* server.cc (create_fetch_memtags_reply)
	(parse_store_memtags_request): New
	functions.
	(handle_general_set): Handle the QMemTags packet.
	(parse_fetch_memtags_request): New function.
	(handle_query): Handle the qMemTags packet and advertise memory
	tagging support.
	(captured_main): Initialize memory tagging flag.
	* server.h (struct client_state): Initialize memory tagging flag.
	* target.cc (process_stratum_target::supports_memory_tagging)
	(process_stratum_target::fetch_memtags)
	(process_stratum_target::store_memtags): New methods.
	* target.h: Include gdbsupport/byte-vector.h.
	(class process_stratum_target) <supports_memory_tagging>
	<fetch_memtags, store_memtags>: New class virtual methods.
	(target_supports_memory_tagging): Define.

1 files changed, 3 insertions, 0 deletions

diff --git a/gdbserver/server.h b/gdbserver/server.h
index 416544c..3e28073 100644
--- a/gdbserver/server.h
+++ b/gdbserver/server.h
@@ -190,6 +190,9 @@ struct client_state
 
   int current_traceframe = -1;
 
+  /* If true, memory tagging features are supported.  */
+  bool memory_tagging_feature = false;
+
 };
 
 client_state &get_client_state ();