Fix/gdbstub continuation crash (#1671)

* Define `SimpleTimerCallback` - used in original GDB stub PR but this change was omitted
* Improve gdbstub debugging
* Add missing `return` statements in LiveDebug sample
* Simplify code now that `m_printf` supports flash strings directly
* Add `queueBreak` command

Sming/Makefile-rboot.mk

@@ -50,8 +50,6 @@ RBOOT_E2_SECTS     ?= .text .data .rodata
 RBOOT_E2_USER_ARGS ?= -quiet -bin -boot2
 # GDB path
 GDB ?= $(ESP_HOME)/xtensa-lx106-elf/bin/xtensa-lx106-elf-gdb
-# File containing boot ROM debug symbols for GDB
-BOOTROM_ELF := bootrom.elf
 
 ## COM port parameters
 # Default COM port speed (generic)
@@ -255,6 +253,7 @@ endif
 ifeq ($(ENABLE_GDB), 1)
 	CFLAGS += -ggdb -DENABLE_GDB=1
 	MODULES += $(SMING_HOME)/gdb
+	GDB_SYMBOLS := gdb_symbols
 endif
 
 ifeq ($(SMING_RELEASE),1)
@@ -542,11 +541,13 @@ endef
 
 .PHONY: all checkdirs spiff_update spiff_clean clean kill_term terminal gdb
 
-all: $(USER_LIBDIR)/lib$(LIBSMING).a checkdirs $(LIBMAIN_DST) $(RBOOT_BIN) $(RBOOT_ROM_0) $(RBOOT_ROM_1) $(SPIFF_BIN_OUT) $(FW_FILE_1) $(FW_FILE_2) $(BUILD_BASE)/$(BOOTROM_ELF)
+all: $(USER_LIBDIR)/lib$(LIBSMING).a checkdirs $(LIBMAIN_DST) $(RBOOT_BIN) $(RBOOT_ROM_0) $(RBOOT_ROM_1) $(SPIFF_BIN_OUT) $(FW_FILE_1) $(FW_FILE_2) $(GDB_SYMBOLS)
 
-# File contains boot rom symbols required by GDB, put it somewhere easy to find
-$(BUILD_BASE)/$(BOOTROM_ELF):
-	cp $(SMING_HOME)/gdb/$(BOOTROM_ELF) $(BUILD_BASE)
+# Copy symbols required by GDB into build directory
+gdb_symbols: $(BUILD_BASE)/bootrom.elf
+
+$(BUILD_BASE)/%.elf:
+	cp $(SMING_HOME)/gdb/symbols/$(notdir $@) $@
 
 $(RBOOT_BIN):
 	$(MAKE) -C $(THIRD_PARTY_DIR)/rboot RBOOT_GPIO_ENABLED=$(RBOOT_GPIO_ENABLED) RBOOT_SILENT=$(RBOOT_SILENT)

Sming/SmingCore/SimpleTimer.h

@@ -37,6 +37,8 @@ extern "C" {
 */
 #define MAX_OS_TIMER_INTERVAL_US 268435000
 
+typedef os_timer_func_t* SimpleTimerCallback;
+
 class SimpleTimer
 {
 public:
@@ -89,7 +91,7 @@ class SimpleTimer
      *  @param  interrupt Function to be called on timer trigger
      *  @note   Classic c-type callback method
      */
-	void setCallback(os_timer_func_t callback, void* arg = nullptr)
+	void setCallback(SimpleTimerCallback callback, void* arg = nullptr)
 	{
 		stop();
 		ets_timer_setfn(&osTimer, callback, arg);

Sming/appspecific/gdb/gdb_hooks.cpp

@@ -120,10 +120,7 @@ void dumpExceptionInfo()
 				"***** Fatal exception %u"),
 			 reg.cause);
 	if(reg.cause <= EXCCAUSE_MAX) {
-		char name[32];
-		memcpy_P(name, exceptionNames[reg.cause], sizeof(name));
-		name[sizeof(name) - 1] = '\0';
-		m_printf(_F(" (%s)"), name);
+		m_printf(_F(" (%s)"), exceptionNames[reg.cause]);
 	}
 	m_puts("\r\n");
 
@@ -243,7 +240,6 @@ static unsigned IRAM_ATTR __gdb_no_op(void)
 #define NOOP __attribute__((weak, alias("__gdb_no_op")))
 
 void gdb_enable(bool state) NOOP;
-void gdb_do_break(void) NOOP;
 GdbState gdb_present(void) NOOP;
 void gdb_on_attach(bool attached) NOOP;
 void gdb_detach(void) NOOP;

Sming/appspecific/gdb/gdbstub-entry.S

@@ -213,6 +213,10 @@ gdbstub_init_debug_entry:
 	ASATTR_GDBFN
 	.align 4
 gdbstub_icount_ena_single_step:
+
+//Make sure we're running at sufficiently high interrupt level to prevent early triggering
+	rsil a2,XCHAL_DEBUGLEVEL
+
 	movi	a3, XCHAL_DEBUGLEVEL //Only count steps in non-debug mode
 	movi	a2, -2
 	wsr		a3, ICOUNTLEVEL

Sming/gdb/GdbPacket.cpp

@@ -15,14 +15,19 @@
 // Send the start of a packet; reset checksum calculation.
 void ATTR_GDBEXTERNFN GdbPacket::start()
 {
+#if GDBSTUB_ENABLE_DEBUG
+	m_puts(_F("> PKT "));
+#endif
 	gdbSendChar('$');
 }
 
 void ATTR_GDBEXTERNFN GdbPacket::end()
 {
 	gdbSendChar('#');
 	writeHexByte(checksum);
-	debug_i("> PKT [%u]", packetLength);
+#if GDBSTUB_ENABLE_DEBUG
+	m_puts("\r\n");
+#endif
 }
 
 void ATTR_GDBEXTERNFN GdbPacket::writeChar(char c)

Sming/gdb/gdbcmds

@@ -1,5 +1,5 @@
 # Enable this if you want to log all traffic between GDB and the stub
-# set remotelogfile gdb_rsp_logfile.txt
+#set remotelogfile gdb_rsp_logfile.txt
 
 # ESP8266 HW limits the number of breakpoints/watchpoints
 set remote hardware-breakpoint-limit 1
@@ -29,6 +29,9 @@ file out/build/app_0.out
 # See https://github.com/jcmvbkbc/esp-elf-rom
 add-symbol-file out/build/bootrom.elf 0x40000000 -readnow
 
+# Useful for lower-level debugging to see the result of stepping through assembler code
+#set disassemble-next-line on
+
 # Change the following to your serial port and baud
 #set serial baud 115200
 #target remote /dev/ttyUSB0

Sming/gdb/gdbhostio.cpp

@@ -113,7 +113,7 @@ void ATTR_GDBEXTERNFN gdbHandleHostIo(char* commandBuffer, unsigned cmdLen)
 		debug_i("File:pread(%d, %u, %u)", fd, count, offset);
 
 		packet.writeChar('F');
-		if(fileSeek(fd, offset, eSO_FileStart) == offset) {
+		if(fileSeek(fd, offset, eSO_FileStart) == int(offset)) {
 			count = fileRead(fd, commandBuffer, count);
 			if(int(count) >= 0) {
 				packet.writeHexWord16(count);
@@ -139,7 +139,7 @@ void ATTR_GDBEXTERNFN gdbHandleHostIo(char* commandBuffer, unsigned cmdLen)
 		debug_i("File:pwrite(%d, %u, %u)", fd, offset, size);
 
 		packet.writeChar('F');
-		if(fileSeek(fd, offset, eSO_FileStart) == offset) {
+		if(fileSeek(fd, offset, eSO_FileStart) == int(offset)) {
 			int count = fileWrite(fd, data, size);
 			if(count >= 0) {
 				packet.writeHexWord16(count);

Sming/gdb/gdbstub-cfg.h

@@ -54,15 +54,6 @@
 #define GDBSTUB_ENABLE_DEBUG 0
 #endif
 
-/*
- * The HardwareTimer defaults to non-maskable mode, and will continue to operate whilst paused.
- * Set this value to 1 to disable during a debugging exception, and restore it afterwards.
- * Note that to debug HardwareTimer callback routines, the timer must be initialise in maskable mode.
- */
-#ifndef GDBSTUB_PAUSE_HARDWARE_TIMER
-#define GDBSTUB_PAUSE_HARDWARE_TIMER 0
-#endif
-
 /*
  * Espressif provide a patched version of GDB which emits only those registered present in the lx106.
  * Set to 0 if an unpatched version of GDB is used.
@@ -102,7 +93,7 @@
  * characters are passed through to the application via UART2.
  * If your application uses the serial port for terminal (text) communications you should be OK,
  * but binary transfers are likely to cause problems and this option should probably be disabled.
- * Instead, use GDBSTUB_BREAK_ON_INIT, or call gdbstub_do_break() in your application.
+ * Instead, use GDBSTUB_BREAK_ON_INIT, or call gdb_do_break() in your application.
  *
  * Specify:
  *  0 to disable Ctrl+C break checking completely
@@ -142,7 +133,7 @@
  * If undefined, calls will do nothing and return -1.
  */
 #ifndef GDBSTUB_ENABLE_SYSCALL
-#define GDBSTUB_ENABLE_SYSCALL 1
+#define GDBSTUB_ENABLE_SYSCALL 0
 #endif
 
 /*
@@ -178,7 +169,7 @@
  * Set to 0 to wait indefinitely.
  */
 #ifndef GDBSTUB_UART_READ_TIMEOUT
-#define GDBSTUB_UART_READ_TIMEOUT 2000
+#define GDBSTUB_UART_READ_TIMEOUT 0
 #endif
 
 /*