From eeae8c4261e529f45ded618a6f92c32cd8160f3e Mon Sep 17 00:00:00 2001
From: Tim Newsome <tim@sifive.com>
Date: Mon, 2 Apr 2018 13:37:53 -0700
Subject: [PATCH] Add gdb_report_register_access_error command

This replaces the earlier mechanism which would propagate errors only
for targets that decided they wanted to. It was suggested by Matthias
Welwarsky from the OpenOCD team.

Change-Id: Ibe8e97644abb47aff26d74b8280377d42615a4d3
---
 src/server/gdb_server.c  | 27 +++++++++++++++++++++++----
 src/target/riscv/riscv.c |  1 -
 src/target/target.h      |  8 --------
 3 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c
index 836e78362..4a5480352 100644
--- a/src/server/gdb_server.c
+++ b/src/server/gdb_server.c
@@ -126,6 +126,9 @@ static int gdb_flash_program = 1;
  * Disabled by default.
  */
 static int gdb_report_data_abort;
+/* If set, errors when accessing registers are reported to gdb. Disabled by
+ * default. */
+static int gdb_report_register_access_error;
 
 /* set if we are sending target descriptions to gdb
  * via qXfer:features:read packet */
@@ -1174,7 +1177,7 @@ static int gdb_get_registers_packet(struct connection *connection,
 	for (i = 0; i < reg_list_size; i++) {
 		if (!reg_list[i]->valid) {
 			retval = reg_list[i]->type->get(reg_list[i]);
-			if (retval != ERROR_OK && target->propagate_register_errors) {
+			if (retval != ERROR_OK && gdb_report_register_access_error) {
 				LOG_DEBUG("Couldn't get register %s.", reg_list[i]->name);
 				free(reg_packet);
 				free(reg_list);
@@ -1242,7 +1245,7 @@ static int gdb_set_registers_packet(struct connection *connection,
 		gdb_target_to_reg(target, packet_p, chars, bin_buf);
 
 		retval = reg_list[i]->type->set(reg_list[i], bin_buf);
-		if (retval != ERROR_OK && target->propagate_register_errors) {
+		if (retval != ERROR_OK && gdb_report_register_access_error) {
 			LOG_DEBUG("Couldn't set register %s.", reg_list[i]->name);
 			free(reg_list);
 			free(bin_buf);
@@ -1289,7 +1292,7 @@ static int gdb_get_register_packet(struct connection *connection,
 
 	if (!reg_list[reg_num]->valid) {
 		retval = reg_list[reg_num]->type->get(reg_list[reg_num]);
-		if (retval != ERROR_OK && target->propagate_register_errors) {
+		if (retval != ERROR_OK && gdb_report_register_access_error) {
 			LOG_DEBUG("Couldn't get register %s.", reg_list[reg_num]->name);
 			free(reg_list);
 			return gdb_error(connection, retval);
@@ -1349,7 +1352,7 @@ static int gdb_set_register_packet(struct connection *connection,
 	gdb_target_to_reg(target, separator + 1, chars, bin_buf);
 
 	retval = reg_list[reg_num]->type->set(reg_list[reg_num], bin_buf);
-	if (retval != ERROR_OK && target->propagate_register_errors) {
+	if (retval != ERROR_OK && gdb_report_register_access_error) {
 		LOG_DEBUG("Couldn't set register %s.", reg_list[reg_num]->name);
 		free(bin_buf);
 		free(reg_list);
@@ -3209,6 +3212,15 @@ COMMAND_HANDLER(handle_gdb_report_data_abort_command)
 	return ERROR_OK;
 }
 
+COMMAND_HANDLER(handle_gdb_report_register_access_error)
+{
+	if (CMD_ARGC != 1)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	COMMAND_PARSE_ENABLE(CMD_ARGV[0], gdb_report_register_access_error);
+	return ERROR_OK;
+}
+
 /* gdb_breakpoint_override */
 COMMAND_HANDLER(handle_gdb_breakpoint_override_command)
 {
@@ -3330,6 +3342,13 @@ static const struct command_registration gdb_command_handlers[] = {
 		.help = "enable or disable reporting data aborts",
 		.usage = "('enable'|'disable')"
 	},
+	{
+		.name = "gdb_report_register_access_error",
+		.handler = handle_gdb_report_register_access_error,
+		.mode = COMMAND_CONFIG,
+		.help = "enable or disable reporting register access errors",
+		.usage = "('enable'|'disable')"
+	},
 	{
 		.name = "gdb_breakpoint_override",
 		.handler = handle_gdb_breakpoint_override_command,
diff --git a/src/target/riscv/riscv.c b/src/target/riscv/riscv.c
index 3a7fe4150..2e980dcb4 100644
--- a/src/target/riscv/riscv.c
+++ b/src/target/riscv/riscv.c
@@ -247,7 +247,6 @@ static int riscv_init_target(struct command_context *cmd_ctx,
 		struct target *target)
 {
 	LOG_DEBUG("riscv_init_target()");
-	target->propagate_register_errors = true;
 	target->arch_info = calloc(1, sizeof(riscv_info_t));
 	if (!target->arch_info)
 		return ERROR_FAIL;
diff --git a/src/target/target.h b/src/target/target.h
index c11a626f8..0096cae10 100644
--- a/src/target/target.h
+++ b/src/target/target.h
@@ -204,14 +204,6 @@ struct target {
 
 	/* file-I/O information for host to do syscall */
 	struct gdb_fileio_info *fileio_info;
-
-	/**
-	 * When true, send gdb an error result when reading/writing a register
-	 * fails. This must be false for some ARM targets (Cortex-M3), where a 'g'
-	 * packet results in an attempt to read 'r0', which fails, which causes gdb
-	 * to close the connection.
-	 */
-	bool propagate_register_errors;
 };
 
 struct target_list {