target: Add calculate_checksum command

This command allows to calculate the checksum of a memory region to
verify its contents against a known value. Unlike 'verify_image_checksum',
this command requires no file and accepts arbitrary memory addresses and
sizes.

Change-Id: I0f7309999bc7268e58af533695bcfaa3c1a5fc24
Signed-off-by: Marc Schink <[email protected]>
Reviewed-on: https://review.openocd.org/c/openocd/+/9971
Reviewed-by: Antonio Borneo <[email protected]>
Tested-by: jenkins
Reviewed-by: Tomas Vanek <[email protected]>

doc/openocd.texi

@@ -5605,6 +5605,36 @@ read_memory 0x20000000 32 2
 @end example
 @end deffn
 
+@anchor{target_calculate_checksum}
+@deffn {Command} {$target_name calculate_checksum} address size
+Calculates the checksum of the memory region starting at @var{address} with a
+length of @var{size}.
+
+The checksum algorithm uses a 32-bit cyclic redundancy check (CRC) with the
+polynomial @code{0x04c11db7} and an initial seed of @code{0xffffffff}. There is
+no input or output reflection, and the XOR output mask is @code{0x00000000}.
+
+If available, the checksum is calculated on the target device using a loader
+function executed in the working area. This accelerates the calculation and
+avoids transferring the memory contents to the host.
+
+For example, to calculate the checksum of 1 KiB starting at address
+@code{0x08000000}, use the following command:
+@example
+calculate_checksum 0x08000000 1024
+0x4fae1a88
+@end example
+
+In Python, for example, the checksum for verification can be calculated as
+follows:
+@example
+from crccheck.crc import Crc32Mpeg2
+
+data = b'deadbeef'
+checksum = Crc32Mpeg2.calc(data, initvalue=0xffffffff)
+@end example
+@end deffn
+
 @deffn {Command} {$target_name cget} queryparm
 Each configuration parameter accepted by
 @command{$target_name configure}
@@ -10340,6 +10370,13 @@ Returns current time since the Epoch in ms
 Useful to compute delays in Tcl.
 @end deffn
 
+@deffn {Command} {calculate_checksum} address size
+Calculates the checksum of the memory region starting at @var{address} with a
+length of @var{size}.
+
+@xref{target_calculate_checksum,, $target_name calculate_checksum} for more details.
+@end deffn
+
 @node Architecture and Core Commands
 @chapter Architecture and Core Commands
 @cindex Architecture Specific Commands

src/target/target.c

@@ -3939,6 +3939,37 @@ COMMAND_HANDLER(handle_test_image_command)
 	return CALL_COMMAND_HANDLER(handle_verify_image_command_internal, IMAGE_TEST);
 }
 
+COMMAND_HANDLER(handle_calculate_checksum_command)
+{
+	if (CMD_ARGC != 2)
+		return ERROR_COMMAND_SYNTAX_ERROR;
+
+	struct target *target = get_current_target_or_null(CMD_CTX);
+
+	if (!target) {
+		command_print(CMD, "no target selected");
+		return ERROR_FAIL;
+	}
+
+	target_addr_t address;
+	COMMAND_PARSE_ADDRESS(CMD_ARGV[0], address);
+
+	uint32_t length;
+	COMMAND_PARSE_NUMBER(u32, CMD_ARGV[1], length);
+
+	uint32_t checksum;
+	int retval = target_checksum_memory(target, address, length, &checksum);
+
+	if (retval != ERROR_OK) {
+		command_print(CMD, "checksum calculation failed");
+		return retval;
+	}
+
+	command_print(CMD, "0x%" PRIx32, checksum);
+
+	return ERROR_OK;
+}
+
 static int handle_bp_command_list(struct command_invocation *cmd)
 {
 	struct target *target = get_current_target(cmd->ctx);
@@ -5707,6 +5738,12 @@ static const struct command_registration target_instance_command_handlers[] = {
 		.help = "Write Tcl list of 8/16/32/64 bit numbers to target memory",
 		.usage = "address width data ['phys']",
 	},
+	{
+		.name = "calculate_checksum",
+		.handler = handle_calculate_checksum_command,
+		.mode = COMMAND_EXEC,
+		.usage = "address size",
+	},
 	{
 		.name = "eventlist",
 		.handler = handle_target_event_list,
@@ -6841,6 +6878,12 @@ static const struct command_registration target_exec_command_handlers[] = {
 		.help = "Write Tcl list of 8/16/32/64 bit numbers to target memory",
 		.usage = "address width data ['phys']",
 	},
+	{
+		.name = "calculate_checksum",
+		.handler = handle_calculate_checksum_command,
+		.mode = COMMAND_EXEC,
+		.usage = "address size",
+	},
 	{
 		.name = "debug_reason",
 		.mode = COMMAND_EXEC,