kgdb_stub.c

linux-2.6.15.6

	mem_to_hex((char *) registers, out_buffer, NUMREGBYTES);
	put_packet(out_buffer);
}

/* Set register contents - currently can't set other thread's registers */
static void set_regs_msg(void)
{
#ifdef CONFIG_KGDB_THREAD
	if (!current_thread) {
#endif
		kgdb_regs_to_gdb_regs(&trap_registers, registers);
		hex_to_mem(&in_buffer[1], (char *) registers, NUMREGBYTES);
		gdb_regs_to_kgdb_regs(registers, &trap_registers);
		send_ok_msg();
#ifdef CONFIG_KGDB_THREAD
	} else
		send_err_msg();
#endif
}


#ifdef CONFIG_KGDB_THREAD

/* Set the status for a thread */
void set_thread_msg(void)
{
	int threadid;
	struct task_struct *thread = NULL;
	char *ptr;

	switch (in_buffer[1]) {

       	/* To select which thread for gG etc messages, i.e. supported */
	case 'g':

		ptr = &in_buffer[2];
		hex_to_int(&ptr, &threadid);
		thread = get_thread(threadid);

		/* If we haven't found it */
		if (!thread) {
			send_err_msg();
			break;
		}

		/* Set current_thread (or not) */
		if (thread == trapped_thread)
			current_thread = NULL;
		else
			current_thread = thread;
		send_ok_msg();
		break;

	/* To select which thread for cCsS messages, i.e. unsupported */
	case 'c':
		send_ok_msg();
		break;

	default:
		send_empty_msg();
		break;
	}
}

/* Is a thread alive? */
static void thread_status_msg(void)
{
	char *ptr;
	int threadid;
	struct task_struct *thread = NULL;

	ptr = &in_buffer[1];
	hex_to_int(&ptr, &threadid);
	thread = get_thread(threadid);
	if (thread)
		send_ok_msg();
	else
		send_err_msg();
}
/* Send the current thread ID */
static void thread_id_msg(void)
{
	int threadid;
	threadref thref;

	out_buffer[0] = 'Q';
	out_buffer[1] = 'C';

	if (current_thread)
		threadid = current_thread->pid;
	else if (trapped_thread)
		threadid = trapped_thread->pid;
	else /* Impossible, but just in case! */
	{
		send_err_msg();
		return;
	}

	/* Translate pid 0 to PID_MAX for gdb */
	if (threadid == 0) threadid = PID_MAX;

	int_to_threadref(&thref, threadid);
	pack_threadid(out_buffer + 2, &thref);
	out_buffer[2 + BUF_THREAD_ID_SIZE] = '\0';
	put_packet(out_buffer);
}

/* Send thread info */
static void thread_info_msg(void)
{
	struct task_struct *thread = NULL;
	int threadid;
	char *pos;
	threadref thref;

	/* Start with 'm' */
	out_buffer[0] = 'm';
	pos = &out_buffer[1];

	/* For all possible thread IDs - this will overrun if > 44 threads! */
	/* Start at 1 and include PID_MAX (since GDB won't use pid 0...) */
	for (threadid = 1; threadid <= PID_MAX; threadid++) {

		read_lock(&tasklist_lock);
		thread = get_thread(threadid);
		read_unlock(&tasklist_lock);

		/* If it's a valid thread */
		if (thread) {
			int_to_threadref(&thref, threadid);
			pack_threadid(pos, &thref);
			pos += BUF_THREAD_ID_SIZE;
			*pos++ = ',';
		}
	}
	*--pos = 0;		/* Lose final comma */
	put_packet(out_buffer);

}

/* Return printable info for gdb's 'info threads' command */
static void thread_extra_info_msg(void)
{
	int threadid;
	struct task_struct *thread = NULL;
	char buffer[20], *ptr;
	int i;

	/* Extract thread ID */
	ptr = &in_buffer[17];
	hex_to_int(&ptr, &threadid);
	thread = get_thread(threadid);

	/* If we don't recognise it, say so */
	if (thread == NULL)
		strcpy(buffer, "(unknown)");
	else
		strcpy(buffer, thread->comm);

	/* Construct packet */
	for (i = 0, ptr = out_buffer; buffer[i]; i++)
		ptr = pack_hex_byte(ptr, buffer[i]);

	if (thread->thread.pc == (unsigned long)ret_from_fork) {
		strcpy(buffer, "<new fork>");
		for (i = 0; buffer[i]; i++)
			ptr = pack_hex_byte(ptr, buffer[i]);
	}

	*ptr = '\0';
	put_packet(out_buffer);
}

/* Handle all qFooBarBaz messages - have to use an if statement as
   opposed to a switch because q messages can have > 1 char id. */
static void query_msg(void)
{
	const char *q_start = &in_buffer[1];

	/* qC = return current thread ID */
	if (strncmp(q_start, "C", 1) == 0)
		thread_id_msg();

	/* qfThreadInfo = query all threads (first) */
	else if (strncmp(q_start, "fThreadInfo", 11) == 0)
		thread_info_msg();

	/* qsThreadInfo = query all threads (subsequent). We know we have sent
	   them all after the qfThreadInfo message, so there are no to send */
	else if (strncmp(q_start, "sThreadInfo", 11) == 0)
		put_packet("l");	/* el = last */

	/* qThreadExtraInfo = supply printable information per thread */
	else if (strncmp(q_start, "ThreadExtraInfo", 15) == 0)
		thread_extra_info_msg();

	/* Unsupported - empty message as per spec */
	else
		send_empty_msg();
}
#endif /* CONFIG_KGDB_THREAD */

/*
 * Bring up the ports..
 */
static int kgdb_serial_setup(void)
{
	extern int kgdb_console_setup(struct console *co, char *options);
	struct console dummy;

	kgdb_console_setup(&dummy, 0);

	return 0;
}

/* The command loop, read and act on requests */
static void kgdb_command_loop(const int excep_code, const int trapa_value)
{
	int sigval;

	if (excep_code == NMI_VEC) {
#ifndef CONFIG_KGDB_NMI
		KGDB_PRINTK("Ignoring unexpected NMI?\n");
		return;
#else /* CONFIG_KGDB_NMI */
		if (!kgdb_enabled) {
			kgdb_enabled = 1;
			kgdb_init();
		}
#endif /* CONFIG_KGDB_NMI */
	}

	/* Ignore if we're disabled */
	if (!kgdb_enabled)
		return;

#ifdef CONFIG_KGDB_THREAD
	/* Until GDB specifies a thread */
	current_thread = NULL;
	trapped_thread = current;
#endif

	/* Enter GDB mode (e.g. after detach) */
	if (!kgdb_in_gdb_mode) {
		/* Do serial setup, notify user, issue preemptive ack */
		kgdb_serial_setup();
		KGDB_PRINTK("Waiting for GDB (on %s%d at %d baud)\n",
			    (kgdb_porttype ? kgdb_porttype->name : ""),
			    kgdb_portnum, kgdb_baud);
		kgdb_in_gdb_mode = 1;
		put_debug_char('+');
	}

	/* Reply to host that an exception has occurred */
	sigval = compute_signal(excep_code);
	send_signal_msg(sigval);

	/* TRAP_VEC exception indicates a software trap inserted in place of
	   code by GDB so back up PC by one instruction, as this instruction
	   will later be replaced by its original one.  Do NOT do this for
	   trap 0xff, since that indicates a compiled-in breakpoint which
	   will not be replaced (and we would retake the trap forever) */
	if ((excep_code == TRAP_VEC) && (trapa_value != (0xff << 2))) {
		trap_registers.pc -= 2;
	}

	/* Undo any stepping we may have done */
	undo_single_step();

	while (1) {

		out_buffer[0] = 0;
		get_packet(in_buffer, BUFMAX);

		/* Examine first char of buffer to see what we need to do */
		switch (in_buffer[0]) {

		case '?':	/* Send which signal we've received */
			send_signal_msg(sigval);
			break;

		case 'g':	/* Return the values of the CPU registers */
			send_regs_msg();
			break;

		case 'G':	/* Set the value of the CPU registers */
			set_regs_msg();
			break;

		case 'm':	/* Read LLLL bytes address AA..AA */
			read_mem_msg();
			break;

		case 'M':	/* Write LLLL bytes address AA..AA, ret OK */
			write_mem_msg(0);	/* 0 = data in hex */
			break;

		case 'X':	/* Write LLLL bytes esc bin address AA..AA */
			if (kgdb_bits == '8')
				write_mem_msg(1); /* 1 = data in binary */
			else
				send_empty_msg();
			break;

		case 'C':	/* Continue, signum included, we ignore it */
			continue_with_sig_msg();
			return;

		case 'c':	/* Continue at address AA..AA (optional) */
			continue_msg();
			return;

		case 'S':	/* Step, signum included, we ignore it */
			step_with_sig_msg();
			return;

		case 's':	/* Step one instruction from AA..AA */
			step_msg();
			return;

#ifdef CONFIG_KGDB_THREAD

		case 'H':	/* Task related */
			set_thread_msg();
			break;

		case 'T':	/* Query thread status */
			thread_status_msg();
			break;

		case 'q':	/* Handle query - currently thread-related */
			query_msg();
			break;
#endif

		case 'k':	/* 'Kill the program' with a kernel ? */
			break;

		case 'D':	/* Detach from program, send reply OK */
			kgdb_in_gdb_mode = 0;
			send_ok_msg();
			get_debug_char();
			return;

		default:
			send_empty_msg();
			break;
		}
	}
}

/* There has been an exception, most likely a breakpoint. */
void kgdb_handle_exception(struct pt_regs *regs)
{
	int excep_code, vbr_val;
	int count;
	int trapa_value = ctrl_inl(TRA);

	/* Copy kernel regs (from stack) */
	for (count = 0; count < 16; count++)
		trap_registers.regs[count] = regs->regs[count];
	trap_registers.pc = regs->pc;
	trap_registers.pr = regs->pr;
	trap_registers.sr = regs->sr;
	trap_registers.gbr = regs->gbr;
	trap_registers.mach = regs->mach;
	trap_registers.macl = regs->macl;

	asm("stc vbr, %0":"=r"(vbr_val));
	trap_registers.vbr = vbr_val;

	/* Get excode for command loop call, user access */
	asm("stc r2_bank, %0":"=r"(excep_code));
	kgdb_excode = excep_code;

	/* Other interesting environment items for reference */
	asm("stc r6_bank, %0":"=r"(kgdb_g_imask));
	kgdb_current = current;
	kgdb_trapa_val = trapa_value;

	/* Act on the exception */
	kgdb_command_loop(excep_code >> 5, trapa_value);

	kgdb_current = NULL;

	/* Copy back the (maybe modified) registers */
	for (count = 0; count < 16; count++)
		regs->regs[count] = trap_registers.regs[count];
	regs->pc = trap_registers.pc;
	regs->pr = trap_registers.pr;
	regs->sr = trap_registers.sr;
	regs->gbr = trap_registers.gbr;
	regs->mach = trap_registers.mach;
	regs->macl = trap_registers.macl;

	vbr_val = trap_registers.vbr;
	asm("ldc %0, vbr": :"r"(vbr_val));

	return;
}

/* Trigger a breakpoint by function */
void breakpoint(void)
{
	if (!kgdb_enabled) {
		kgdb_enabled = 1;
		kgdb_init();
	}
	BREAKPOINT();
}

/* Initialise the KGDB data structures and serial configuration */
int kgdb_init(void)
{
	if (!kgdb_enabled)
		return 1;

	in_nmi = 0;
	kgdb_nofault = 0;
	stepped_opcode = 0;
	kgdb_in_gdb_mode = 0;

	if (kgdb_serial_setup() != 0) {
		KGDB_PRINTK("serial setup error\n");
		return -1;
	}

	/* Init ptr to exception handler */
	kgdb_debug_hook = kgdb_handle_exception;
	kgdb_bus_err_hook = kgdb_handle_bus_error;

	/* Enter kgdb now if requested, or just report init done */
	if (kgdb_halt) {
		kgdb_in_gdb_mode = 1;
		put_debug_char('+');
		breakpoint();
	}
	else
	{
		KGDB_PRINTK("stub is initialized.\n");
	}

	return 0;
}

/* Make function available for "user messages"; console will use it too. */

char gdbmsgbuf[BUFMAX];
#define MAXOUT ((BUFMAX-2)/2)

static void kgdb_msg_write(const char *s, unsigned count)
{
	int i;
	int wcount;
	char *bufptr;

	/* 'O'utput */
	gdbmsgbuf[0] = 'O';

	/* Fill and send buffers... */
	while (count > 0) {
		bufptr = gdbmsgbuf + 1;

		/* Calculate how many this time */
		wcount = (count > MAXOUT) ? MAXOUT : count;
		
		/* Pack in hex chars */
		for (i = 0; i < wcount; i++)
			bufptr = pack_hex_byte(bufptr, s[i]);
		*bufptr = '\0';

		/* Move up */
		s += wcount;
		count -= wcount;

		/* Write packet */
		put_packet(gdbmsgbuf);
	}
}

static void kgdb_to_gdb(const char *s)
{
	kgdb_msg_write(s, strlen(s));
}

#ifdef CONFIG_SH_KGDB_CONSOLE
void kgdb_console_write(struct console *co, const char *s, unsigned count)
{
	/* Bail if we're not talking to GDB */
	if (!kgdb_in_gdb_mode)
		return;

	kgdb_msg_write(s, count);
}
#endif