gdb-stub.c

LINUX 2.6.17.4的源码

	/*
	 * These are unconditional and in j_format.
	 */
	case jal_op:
	case j_op:
		is_branch = 1;
		targ += 4;
		targ >>= 28;
		targ <<= 28;
		targ |= (insn.j_format.target << 2);
		break;

	/*
	 * These are conditional.
	 */
	case beq_op:
	case beql_op:
	case bne_op:
	case bnel_op:
	case blez_op:
	case blezl_op:
	case bgtz_op:
	case bgtzl_op:
	case cop0_op:
	case cop1_op:
	case cop2_op:
	case cop1x_op:
		is_branch = is_cond = 1;
		targ += 4 + (insn.i_format.simmediate << 2);
		break;
	}

	if (is_branch) {
		i = 0;
		if (is_cond && targ != (regs->cp0_epc + 8)) {
			step_bp[i].addr = regs->cp0_epc + 8;
			step_bp[i++].val = *(unsigned *)(regs->cp0_epc + 8);
			*(unsigned *)(regs->cp0_epc + 8) = BP;
		}
		step_bp[i].addr = targ;
		step_bp[i].val  = *(unsigned *)targ;
		*(unsigned *)targ = BP;
	} else {
		step_bp[0].addr = regs->cp0_epc + 4;
		step_bp[0].val  = *(unsigned *)(regs->cp0_epc + 4);
		*(unsigned *)(regs->cp0_epc + 4) = BP;
	}
}

/*
 *  If asynchronously interrupted by gdb, then we need to set a breakpoint
 *  at the interrupted instruction so that we wind up stopped with a
 *  reasonable stack frame.
 */
static struct gdb_bp_save async_bp;

/*
 * Swap the interrupted EPC with our asynchronous breakpoint routine.
 * This is safer than stuffing the breakpoint in-place, since no cache
 * flushes (or resulting smp_call_functions) are required.  The
 * assumption is that only one CPU will be handling asynchronous bp's,
 * and only one can be active at a time.
 */
extern spinlock_t smp_call_lock;

void set_async_breakpoint(unsigned long *epc)
{
	/* skip breaking into userland */
	if ((*epc & 0x80000000) == 0)
		return;

#ifdef CONFIG_SMP
	/* avoid deadlock if someone is make IPC */
	if (spin_is_locked(&smp_call_lock))
		return;
#endif

	async_bp.addr = *epc;
	*epc = (unsigned long)async_breakpoint;
}

static void kgdb_wait(void *arg)
{
	unsigned flags;
	int cpu = smp_processor_id();

	local_irq_save(flags);

	__raw_spin_lock(&kgdb_cpulock[cpu]);
	__raw_spin_unlock(&kgdb_cpulock[cpu]);

	local_irq_restore(flags);
}

/*
 * GDB stub needs to call kgdb_wait on all processor with interrupts
 * disabled, so it uses it's own special variant.
 */
static int kgdb_smp_call_kgdb_wait(void)
{
#ifdef CONFIG_SMP
	struct call_data_struct data;
	int i, cpus = num_online_cpus() - 1;
	int cpu = smp_processor_id();

	/*
	 * Can die spectacularly if this CPU isn't yet marked online
	 */
	BUG_ON(!cpu_online(cpu));

	if (!cpus)
		return 0;

	if (spin_is_locked(&smp_call_lock)) {
		/*
		 * Some other processor is trying to make us do something
		 * but we're not going to respond... give up
		 */
		return -1;
		}

	/*
	 * We will continue here, accepting the fact that
	 * the kernel may deadlock if another CPU attempts
	 * to call smp_call_function now...
	 */

	data.func = kgdb_wait;
	data.info = NULL;
	atomic_set(&data.started, 0);
	data.wait = 0;

	spin_lock(&smp_call_lock);
	call_data = &data;
	mb();

	/* Send a message to all other CPUs and wait for them to respond */
	for (i = 0; i < NR_CPUS; i++)
		if (cpu_online(i) && i != cpu)
			core_send_ipi(i, SMP_CALL_FUNCTION);

	/* Wait for response */
	/* FIXME: lock-up detection, backtrace on lock-up */
	while (atomic_read(&data.started) != cpus)
		barrier();

	call_data = NULL;
	spin_unlock(&smp_call_lock);
#endif

	return 0;
}

/*
 * This function does all command processing for interfacing to gdb.  It
 * returns 1 if you should skip the instruction at the trap address, 0
 * otherwise.
 */
void handle_exception (struct gdb_regs *regs)
{
	int trap;			/* Trap type */
	int sigval;
	long addr;
	int length;
	char *ptr;
	unsigned long *stack;
	int i;
	int bflag = 0;

	kgdb_started = 1;

	/*
	 * acquire the big kgdb spinlock
	 */
	if (!spin_trylock(&kgdb_lock)) {
		/*
		 * some other CPU has the lock, we should go back to
		 * receive the gdb_wait IPC
		 */
		return;
	}

	/*
	 * If we're in async_breakpoint(), restore the real EPC from
	 * the breakpoint.
	 */
	if (regs->cp0_epc == (unsigned long)async_breakinst) {
		regs->cp0_epc = async_bp.addr;
		async_bp.addr = 0;
	}

	/*
	 * acquire the CPU spinlocks
	 */
	for (i = num_online_cpus()-1; i >= 0; i--)
		if (__raw_spin_trylock(&kgdb_cpulock[i]) == 0)
			panic("kgdb: couldn't get cpulock %d\n", i);

	/*
	 * force other cpus to enter kgdb
	 */
	kgdb_smp_call_kgdb_wait();

	/*
	 * If we're in breakpoint() increment the PC
	 */
	trap = (regs->cp0_cause & 0x7c) >> 2;
	if (trap == 9 && regs->cp0_epc == (unsigned long)breakinst)
		regs->cp0_epc += 4;

	/*
	 * If we were single_stepping, restore the opcodes hoisted
	 * for the breakpoint[s].
	 */
	if (step_bp[0].addr) {
		*(unsigned *)step_bp[0].addr = step_bp[0].val;
		step_bp[0].addr = 0;

		if (step_bp[1].addr) {
			*(unsigned *)step_bp[1].addr = step_bp[1].val;
			step_bp[1].addr = 0;
		}
	}

	stack = (long *)regs->reg29;			/* stack ptr */
	sigval = computeSignal(trap);

	/*
	 * reply to host that an exception has occurred
	 */
	ptr = output_buffer;

	/*
	 * Send trap type (converted to signal)
	 */
	*ptr++ = 'T';
	*ptr++ = hexchars[sigval >> 4];
	*ptr++ = hexchars[sigval & 0xf];

	/*
	 * Send Error PC
	 */
	*ptr++ = hexchars[REG_EPC >> 4];
	*ptr++ = hexchars[REG_EPC & 0xf];
	*ptr++ = ':';
	ptr = mem2hex((char *)&regs->cp0_epc, ptr, sizeof(long), 0);
	*ptr++ = ';';

	/*
	 * Send frame pointer
	 */
	*ptr++ = hexchars[REG_FP >> 4];
	*ptr++ = hexchars[REG_FP & 0xf];
	*ptr++ = ':';
	ptr = mem2hex((char *)&regs->reg30, ptr, sizeof(long), 0);
	*ptr++ = ';';

	/*
	 * Send stack pointer
	 */
	*ptr++ = hexchars[REG_SP >> 4];
	*ptr++ = hexchars[REG_SP & 0xf];
	*ptr++ = ':';
	ptr = mem2hex((char *)&regs->reg29, ptr, sizeof(long), 0);
	*ptr++ = ';';

	*ptr++ = 0;
	putpacket(output_buffer);	/* send it off... */

	/*
	 * Wait for input from remote GDB
	 */
	while (1) {
		output_buffer[0] = 0;
		getpacket(input_buffer);

		switch (input_buffer[0])
		{
		case '?':
			output_buffer[0] = 'S';
			output_buffer[1] = hexchars[sigval >> 4];
			output_buffer[2] = hexchars[sigval & 0xf];
			output_buffer[3] = 0;
			break;

		/*
		 * Detach debugger; let CPU run
		 */
		case 'D':
			putpacket(output_buffer);
			goto finish_kgdb;
			break;

		case 'd':
			/* toggle debug flag */
			break;

		/*
		 * Return the value of the CPU registers
		 */
		case 'g':
			ptr = output_buffer;
			ptr = mem2hex((char *)&regs->reg0, ptr, 32*sizeof(long), 0); /* r0...r31 */
			ptr = mem2hex((char *)&regs->cp0_status, ptr, 6*sizeof(long), 0); /* cp0 */
			ptr = mem2hex((char *)&regs->fpr0, ptr, 32*sizeof(long), 0); /* f0...31 */
			ptr = mem2hex((char *)&regs->cp1_fsr, ptr, 2*sizeof(long), 0); /* cp1 */
			ptr = mem2hex((char *)&regs->frame_ptr, ptr, 2*sizeof(long), 0); /* frp */
			ptr = mem2hex((char *)&regs->cp0_index, ptr, 16*sizeof(long), 0); /* cp0 */
			break;

		/*
		 * set the value of the CPU registers - return OK
		 */
		case 'G':
		{
			ptr = &input_buffer[1];
			hex2mem(ptr, (char *)&regs->reg0, 32*sizeof(long), 0, 0);
			ptr += 32*(2*sizeof(long));
			hex2mem(ptr, (char *)&regs->cp0_status, 6*sizeof(long), 0, 0);
			ptr += 6*(2*sizeof(long));
			hex2mem(ptr, (char *)&regs->fpr0, 32*sizeof(long), 0, 0);
			ptr += 32*(2*sizeof(long));
			hex2mem(ptr, (char *)&regs->cp1_fsr, 2*sizeof(long), 0, 0);
			ptr += 2*(2*sizeof(long));
			hex2mem(ptr, (char *)&regs->frame_ptr, 2*sizeof(long), 0, 0);
			ptr += 2*(2*sizeof(long));
			hex2mem(ptr, (char *)&regs->cp0_index, 16*sizeof(long), 0, 0);
			strcpy(output_buffer,"OK");
		 }
		break;

		/*
		 * mAA..AA,LLLL  Read LLLL bytes at address AA..AA
		 */
		case 'm':
			ptr = &input_buffer[1];

			if (hexToLong(&ptr, &addr)
				&& *ptr++ == ','
				&& hexToInt(&ptr, &length)) {
				if (mem2hex((char *)addr, output_buffer, length, 1))
					break;
				strcpy (output_buffer, "E03");
			} else
				strcpy(output_buffer,"E01");
			break;

		/*
		 * XAA..AA,LLLL: Write LLLL escaped binary bytes at address AA.AA
		 */
		case 'X':
			bflag = 1;
			/* fall through */

		/*
		 * MAA..AA,LLLL: Write LLLL bytes at address AA.AA return OK
		 */
		case 'M':
			ptr = &input_buffer[1];

			if (hexToLong(&ptr, &addr)
				&& *ptr++ == ','
				&& hexToInt(&ptr, &length)
				&& *ptr++ == ':') {
				if (hex2mem(ptr, (char *)addr, length, bflag, 1))
					strcpy(output_buffer, "OK");
				else
					strcpy(output_buffer, "E03");
			}
			else
				strcpy(output_buffer, "E02");
			break;

		/*
		 * cAA..AA    Continue at address AA..AA(optional)
		 */
		case 'c':
			/* try to read optional parameter, pc unchanged if no parm */

			ptr = &input_buffer[1];
			if (hexToLong(&ptr, &addr))
				regs->cp0_epc = addr;

			goto exit_kgdb_exception;
			break;

		/*
		 * kill the program; let us try to restart the machine
		 * Reset the whole machine.
		 */
		case 'k':
		case 'r':
			machine_restart("kgdb restarts machine");
			break;

		/*
		 * Step to next instruction
		 */
		case 's':
			/*
			 * There is no single step insn in the MIPS ISA, so we
			 * use breakpoints and continue, instead.
			 */
			single_step(regs);
			goto exit_kgdb_exception;
			/* NOTREACHED */
			break;

		/*
		 * Set baud rate (bBB)
		 * FIXME: Needs to be written
		 */
		case 'b':
		{
#if 0
			int baudrate;
			extern void set_timer_3();

			ptr = &input_buffer[1];
			if (!hexToInt(&ptr, &baudrate))
			{
				strcpy(output_buffer,"B01");
				break;
			}

			/* Convert baud rate to uart clock divider */

			switch (baudrate)
			{
				case 38400:
					baudrate = 16;
					break;
				case 19200:
					baudrate = 33;
					break;
				case 9600:
					baudrate = 65;
					break;
				default:
					baudrate = 0;
					strcpy(output_buffer,"B02");
					goto x1;
			}

			if (baudrate) {
				putpacket("OK");	/* Ack before changing speed */
				set_timer_3(baudrate); /* Set it */
			}
#endif
		}
		break;

		}			/* switch */

		/*
		 * reply to the request
		 */

		putpacket(output_buffer);

	} /* while */

	return;

finish_kgdb:
	restore_debug_traps();

exit_kgdb_exception:
	/* release locks so other CPUs can go */
	for (i = num_online_cpus()-1; i >= 0; i--)
		__raw_spin_unlock(&kgdb_cpulock[i]);
	spin_unlock(&kgdb_lock);

	__flush_cache_all();
	return;
}

/*
 * This function will generate a breakpoint exception.  It is used at the
 * beginning of a program to sync up with a debugger and can be used
 * otherwise as a quick means to stop program execution and "break" into
 * the debugger.
 */
void breakpoint(void)
{
	if (!initialized)
		return;

	__asm__ __volatile__(
			".globl	breakinst\n\t"
			".set\tnoreorder\n\t"
			"nop\n"
			"breakinst:\tbreak\n\t"
			"nop\n\t"
			".set\treorder"
			);
}

/* Nothing but the break; don't pollute any registers */
void async_breakpoint(void)
{
	__asm__ __volatile__(
			".globl	async_breakinst\n\t"
			".set\tnoreorder\n\t"
			"nop\n"
			"async_breakinst:\tbreak\n\t"
			"nop\n\t"
			".set\treorder"
			);
}

void adel(void)
{
	__asm__ __volatile__(
			".globl\tadel\n\t"
			"lui\t$8,0x8000\n\t"
			"lw\t$9,1($8)\n\t"
			);
}

/*
 * malloc is needed by gdb client in "call func()", even a private one
 * will make gdb happy
 */
static void * __attribute_used__ malloc(size_t size)
{
	return kmalloc(size, GFP_ATOMIC);
}

static void __attribute_used__ free (void *where)
{
	kfree(where);
}

#ifdef CONFIG_GDB_CONSOLE

void gdb_putsn(const char *str, int l)
{
	char outbuf[18];

	if (!kgdb_started)
		return;

	outbuf[0]='O';

	while(l) {
		int i = (l>8)?8:l;
		mem2hex((char *)str, &outbuf[1], i, 0);
		outbuf[(i*2)+1]=0;
		putpacket(outbuf);
		str += i;
		l -= i;
	}
}

static void gdb_console_write(struct console *con, const char *s, unsigned n)
{
	gdb_putsn(s, n);
}

static struct console gdb_console = {
	.name	= "gdb",
	.write	= gdb_console_write,
	.flags	= CON_PRINTBUFFER,
	.index	= -1
};

static int __init register_gdb_console(void)
{
	register_console(&gdb_console);

	return 0;
}

console_initcall(register_gdb_console);

#endif