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, 10 insertions, 2 deletions

diff --git a/gdbserver/remote-utils.h b/gdbserver/remote-utils.h
index 5a8e764..25074bc 100644
--- a/gdbserver/remote-utils.h
+++ b/gdbserver/remote-utils.h
@@ -45,9 +45,17 @@ void prepare_resume_reply (char *buf, ptid_t ptid,
 
 const char *decode_address_to_semicolon (CORE_ADDR *addrp, const char *start);
 void decode_address (CORE_ADDR *addrp, const char *start, int len);
-void decode_m_packet (char *from, CORE_ADDR * mem_addr_ptr,
+
+/* Given an input string FROM, decode MEM_ADDR_PTR, a memory address in hex
+   form,  and LEN_PTR, a length argument in hex form, from the pattern
+   "<MEM_ADDR_PTR>,<LEN_PTR><END_MARKER>", with END_MARKER being an end marker
+   character.  */
+const char *decode_m_packet_params (const char *from, CORE_ADDR *mem_addr_ptr,
+				    unsigned int *len_ptr,
+				    const char end_marker);
+void decode_m_packet (const char *from, CORE_ADDR * mem_addr_ptr,
 		      unsigned int *len_ptr);
-void decode_M_packet (char *from, CORE_ADDR * mem_addr_ptr,
+void decode_M_packet (const char *from, CORE_ADDR * mem_addr_ptr,
 		      unsigned int *len_ptr, unsigned char **to_p);
 int decode_X_packet (char *from, int packet_len, CORE_ADDR * mem_addr_ptr,
 		     unsigned int *len_ptr, unsigned char **to_p);