feature: memwatch: read memory while running

src/Makefile

@@ -2,6 +2,7 @@ PROBE_HOST ?= native
 PLATFORM_DIR = platforms/$(PROBE_HOST)
 VPATH += $(PLATFORM_DIR) target
 ENABLE_DEBUG ?=
+ENABLE_MEMWATCH ?= 1
 
 SYS = $(shell $(CC) -dumpmachine)
 
@@ -116,6 +117,11 @@ CFLAGS += -DPC_HOSTED=0
 include platforms/common/Makefile.inc
 endif
 
+ifeq ($(ENABLE_MEMWATCH), 1)
+CFLAGS += -DENABLE_MEMWATCH
+SRC += memwatch.c
+endif
+
 ifeq ($(ENABLE_RTT), 1)
 CFLAGS += -DENABLE_RTT
 SRC += rtt.c rtt_if.c

src/include/memwatch.h

@@ -0,0 +1,30 @@
+#ifndef MEMWATCH_H
+#define MEMWATCH_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <target.h>
+
+#define MEMWATCH_NUM 8
+/* string length has to be long enough to store an address 0x20000000 */
+#define MEMWATCH_STRLEN 12
+
+typedef enum memwatch_format {
+	MEMWATCH_FMT_SIGNED,
+	MEMWATCH_FMT_UNSIGNED,
+	MEMWATCH_FMT_HEX
+} memwatch_format_e;
+
+typedef struct {
+	uint32_t addr;
+	uint32_t value;
+	char name[MEMWATCH_STRLEN];
+	memwatch_format_e format;
+} memwatch_s;
+
+extern memwatch_s memwatch_table[MEMWATCH_NUM];
+extern uint32_t memwatch_cnt;
+extern bool memwatch_timestamp;
+extern void poll_memwatch(target_s *cur_target);
+
+#endif

src/main.c

@@ -29,6 +29,7 @@
 #include "gdb_packet.h"
 #include "morse.h"
 #include "command.h"
+#include "memwatch.h"
 #ifdef ENABLE_RTT
 #include "rtt.h"
 #endif
@@ -58,6 +59,10 @@ static void bmp_poll_loop(void)
 #ifdef ENABLE_RTT
 		if (rtt_enabled)
 			poll_rtt(cur_target);
+#endif
+#ifdef ENABLE_MEMWATCH
+		if (memwatch_cnt != 0)
+			poll_memwatch(cur_target);
 #endif
 	}
 

src/memwatch.c

@@ -0,0 +1,65 @@
+#include "general.h"
+#include "gdb_packet.h"
+#include "memwatch.h"
+#include "rtt_if.h"
+#if PC_HOSTED == 1
+#include <unistd.h>
+#else
+#include "usb_serial.h"
+#endif
+
+memwatch_s memwatch_table[MEMWATCH_NUM];
+uint32_t memwatch_cnt = 0;
+bool memwatch_timestamp = false;
+
+#ifndef ENABLE_RTT
+uint32_t rtt_write(const char *buf, uint32_t len)
+{
+#if PC_HOSTED == 1
+	return write(1, buf, len);
+#else
+	uint32_t start_ms = platform_time_ms();
+	while (usbd_ep_write_packet(usbdev, CDCACM_UART_ENDPOINT, buf, len) <= 0) {
+		if (platform_time_ms() - start_ms >= 25)
+			return 0; /* drop silently */
+	}
+	return len;
+#endif
+}
+#endif
+
+void poll_memwatch(target_s *cur_target)
+{
+	uint32_t val;
+	char buf[64];
+	char timestamp[64];
+	uint32_t len;
+	if (!cur_target || (memwatch_cnt == 0))
+		return;
+
+	for (uint32_t i = 0; i < memwatch_cnt; i++) {
+		if (!target_mem_read(cur_target, &val, memwatch_table[i].addr, sizeof(val)) &&
+			(val != memwatch_table[i].value)) {
+			if (memwatch_timestamp)
+				snprintf(timestamp, sizeof(timestamp), "%" PRIu32 " ", platform_time_ms());
+			else
+				timestamp[0] = '\0';
+			switch (memwatch_table[i].format) {
+			case MEMWATCH_FMT_SIGNED:
+				len = snprintf(buf, sizeof(buf), "%s%s %" PRId32 "\r\n", timestamp, memwatch_table[i].name, val);
+				break;
+			case MEMWATCH_FMT_UNSIGNED:
+				len = snprintf(buf, sizeof(buf), "%s%s %" PRIu32 "\r\n", timestamp, memwatch_table[i].name, val);
+				break;
+			case MEMWATCH_FMT_HEX:
+			default:
+				len = snprintf(buf, sizeof(buf), "%s%s 0x%" PRIx32 "\r\n", timestamp, memwatch_table[i].name, val);
+				break;
+			}
+			buf[sizeof(buf) - 1] = '\0';
+			rtt_write(buf, len);
+			memwatch_table[i].value = val;
+		}
+	}
+	return;
+}

src/target/cortexm.c

@@ -41,6 +41,7 @@
 #include "command.h"
 #include "gdb_packet.h"
 #include "semihosting.h"
+#include "memwatch.h"
 #include "platform.h"
 
 #include <string.h>
@@ -53,6 +54,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <ctype.h>
 
 #if PC_HOSTED == 1
 
@@ -72,12 +74,18 @@
 #endif
 
 static bool cortexm_vector_catch(target_s *t, int argc, const char **argv);
+#ifdef ENABLE_MEMWATCH
+static bool cortexm_memwatch(target_s *t, int argc, const char **argv);
+#endif
 #if PC_HOSTED == 0
 static bool cortexm_redirect_stdout(target_s *t, int argc, const char **argv);
 #endif
 
 const command_s cortexm_cmd_list[] = {
 	{"vector_catch", cortexm_vector_catch, "Catch exception vectors"},
+#ifdef ENABLE_MEMWATCH
+	{"memwatch", cortexm_memwatch, "Print variable when value changes: [[NAME] [/d|/u|/x] ADDRESS]..."},
+#endif
 #if PC_HOSTED == 0
 	{"redirect_stdout", cortexm_redirect_stdout, "Redirect semihosting stdout to USB UART"},
 #endif
@@ -1376,6 +1384,71 @@ static bool cortexm_vector_catch(target_s *t, int argc, const char **argv)
 	return true;
 }
 
+#ifdef ENABLE_MEMWATCH
+static bool cortexm_memwatch(target_s *t, int argc, const char **argv)
+{
+	memwatch_format_e fmt = MEMWATCH_FMT_HEX;
+	char name[MEMWATCH_STRLEN] = {0};
+	memset(memwatch_table, 0, sizeof(memwatch_table));
+	memwatch_cnt = 0;
+	memwatch_timestamp = false;
+	/* target has to support debugger memory access while running */
+	if (target_mem_access_needs_halt(t)) {
+		gdb_out("memwatch not supported for target\n");
+		return true;
+	}
+	for (int32_t i = 1; i < argc; i++) {
+		if (argv[i][0] == '/') {
+			/* format follows */
+			switch (argv[i][1]) {
+			case 'd':
+				fmt = MEMWATCH_FMT_SIGNED;
+				break;
+			case 'u':
+				fmt = MEMWATCH_FMT_UNSIGNED;
+				break;
+			case 'x':
+				fmt = MEMWATCH_FMT_HEX;
+				break;
+			case 't':
+				memwatch_timestamp = true;
+				break;
+			default:
+				break;
+			}
+		} else if (isalpha(argv[i][0])) {
+			/* name  follows */
+			strncpy(name, argv[i], sizeof(name));
+			name[sizeof(name) - 1] = '\0';
+		} else if (isdigit(argv[i][0])) {
+			/* address follows */
+			uint32_t addr = strtoul(argv[i], NULL, 0);
+
+			/* add new name, format and address to memwatch table */
+			if (name[0] == '\0') {
+				/* no name given, use address as name */
+				snprintf(name, MEMWATCH_STRLEN, "0x%08" PRIx32, addr);
+				name[MEMWATCH_STRLEN - 1] = '\0';
+			}
+			memwatch_table[memwatch_cnt].addr = addr;
+			memwatch_table[memwatch_cnt].value = 0xdeadbeef;
+			memwatch_table[memwatch_cnt].format = fmt;
+			memcpy(memwatch_table[memwatch_cnt].name, name, MEMWATCH_STRLEN);
+			memwatch_cnt++;
+			memset(name, 0, sizeof(name));
+			gdb_outf("0x%x ", addr);
+			if (memwatch_cnt == MEMWATCH_NUM)
+				break;
+		} else {
+			gdb_outf("?");
+			break;
+		}
+	}
+	gdb_outf("\n");
+	return true;
+}
+#endif
+
 #if PC_HOSTED == 0
 static bool cortexm_redirect_stdout(target_s *t, int argc, const char **argv)
 {