path: root/core/cortex-m/panic.c

/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include <stdarg.h>

#include "config.h"
#include "cpu.h"
#include "panic.h"
#include "system.h"
#include "task.h"
#include "timer.h"
#include "uart.h"
#include "util.h"
#include "watchdog.h"


/* This is the size of our private panic stack, if we have one */
#define STACK_SIZE_WORDS	64

/* We save registers here for display by report_panic() */
static struct save_area
{
#ifdef CONFIG_PANIC_NEW_STACK
	uint32_t stack[STACK_SIZE_WORDS];
#endif
	uint32_t saved_regs[11];	/* psp, ipsr, lr, r4-r11 */
} save_area __attribute__((aligned(8)));


void panic_putc(int ch)
{
	uart_emergency_flush();
	if (ch == '\n')
		panic_putc('\r');
	uart_write_char(ch);
	while (uart_tx_ready())
		;
}


void panic_puts(const char *s)
{
	while (*s)
		panic_putc(*s++);
}


void panic_vprintf(const char *format, va_list args)
{
	int pad_width;

	while (*format) {
		int c = *format++;

		/* Copy normal characters */
		if (c != '%') {
			panic_putc(c);
			continue;
		}

		/* Get first format character */
		c = *format++;

		/* Handle %c */
		if (c == 'c') {
			c = va_arg(args, int);
			panic_putc(c);
			continue;
		}

		/* Count padding length (only supported for hex) */
		pad_width = 0;
		while (c >= '0' && c <= '9') {
			pad_width = (10 * pad_width) + c - '0';
			c = *format++;
		}

		if (c == 's') {
			char *vstr;

			vstr = va_arg(args, char *);
			panic_puts(vstr ? vstr : "(null)");
		} else { /* assume 'x' */
			uint32_t v, shift;
			int i;

			v = va_arg(args, uint32_t);
			if (!pad_width)
				pad_width = 8;
			shift = pad_width * 4 - 4;
			for (i = 0; i < pad_width; i++) {
				int ch = '0' + ((v >> shift) & 0xf);

				if (ch > '9')
					ch += 'a' - '9' - 1;
				panic_putc(ch);
				shift -= 4;
			}
		}
	}
}


void panic_printf(const char *format, ...)
{
	va_list args;

	va_start(args, format);
	panic_vprintf(format, args);
	va_end(args);
}


/**
 * Print the name and value of a register
 *
 * This is a convenient helper function for displaying a register value.
 * It shows the register name in a 3 character field, followed by a colon.
 * The register value is regs[index], and this is shown in hex. If regs is
 * NULL, then we display spaces instead.
 *
 * After displaying the value, either a space or \n is displayed depending
 * on the register number, so that (assuming the caller passes all 16
 * registers in sequence) we put 4 values per line like this
 *
 * r0 :0000000b r1 :00000047 r2 :60000000 r3 :200012b5
 * r4 :00000000 r5 :08004e64 r6 :08004e1c r7 :200012a8
 * r8 :08004e64 r9 :00000002 r10:00000000 r11:00000000
 * r12:0000003f sp :200009a0 lr :0800270d pc :0800351a
 *
 * @param regnum	Register number to display (0-15)
 * @param regs		Pointer to array holding the registers, or NULL
 * @param index		Index into array where the register value is present
 */
static void print_reg(int regnum, uint32_t *regs, int index)
{
	static const char regname[] = "r10r11r12sp lr pc ";
	static char rname[3] = "r  ";
	const char *name;

	rname[1] = '0' + regnum;
	name = regnum < 10 ? rname : &regname[(regnum - 10) * 3];
	panic_printf("%c%c%c:", name[0], name[1], name[2]);
	if (regs)
		panic_printf("%8x", regs[index]);
	else
		panic_puts("        ");
	panic_putc((regnum & 3) == 3 ? '\n' : ' ');
}

#ifdef CONFIG_PANIC_HELP
/* Names for each of the bits in the mmfs register, starting at bit 0 */
static const char * const mmfs_name[32] = {
	"Instruction access violation",
	"Data access violation",
	NULL,
	"Unstack from exception violation",
	"Stack from exception violation",
	NULL,
	NULL,
	NULL,

	"Instruction bus error",
	"Precise data bus error",
	"Imprecise data bus error",
	"Unstack from exception bus fault",
	"Stack from exception bus fault",
	NULL,
	NULL,
	NULL,

	"Undefined instructions",
	"Invalid state",
	"Invalid PC",
	"No coprocessor",
	NULL,
	NULL,
	NULL,
	NULL,

	"Unaligned",
	"Divide by 0",
	NULL,
	NULL,

	NULL,
	NULL,
	NULL,
	NULL,
};


/* Names for the first 5 bits in the DFSR */
static const char * const dfsr_name[] = {
	"Halt request",
	"Breakpoint",
	"Data watchpoint/trace",
	"Vector catch",
	"External debug request",
};


/**
 * Helper function to display a separator after the previous item
 *
 * If items have been displayed already, we display a comma separator.
 * In any case, the count of items displayed is incremeneted.
 *
 * @param count		Number of items displayed so far (0 for none)
 */
static void do_separate(int *count)
{
	if (*count)
		panic_puts(", ");
	(*count)++;
}


/**
 * Show a textual representaton of the fault registers
 *
 * A list of detected faults is shown, with no trailing newline.
 *
 * @param mmfs		Value of Memory Manage Fault Status
 * @param hfsr		Value of Hard Fault Status
 * @param dfsr		Value of Debug Fault Status
 */
static void show_fault(uint32_t mmfs, uint32_t hfsr, uint32_t dfsr)
{
	unsigned int upto;
	int count = 0;

	for (upto = 0; upto < 32; upto++) {
		if ((mmfs & (1 << upto)) && mmfs_name[upto]) {
			do_separate(&count);
			panic_puts(mmfs_name[upto]);
		}
	}

	if (hfsr & CPU_NVIC_HFSR_DEBUGEVT) {
		do_separate(&count);
		panic_puts("Debug event");
	}
	if (hfsr & CPU_NVIC_HFSR_FORCED) {
		do_separate(&count);
		panic_puts("Forced hard fault");
	}
	if (hfsr & CPU_NVIC_HFSR_VECTTBL) {
		do_separate(&count);
		panic_puts("Vector table bus fault");
	}

	for (upto = 0; upto < 5; upto++) {
		if ((dfsr & (1 << upto))) {
			do_separate(&count);
			panic_puts(dfsr_name[upto]);
		}
	}
}


/**
 * Show extra information that might be useful to understand a panic()
 *
 * We show fault register information, including the fault address registers
 * if valid.
 */
static void panic_show_extra(void)
{
	uint32_t mmfs;

	mmfs = CPU_NVIC_MMFS;
	show_fault(mmfs, CPU_NVIC_HFSR, CPU_NVIC_DFSR);
	if (mmfs & CPU_NVIC_MMFS_BFARVALID)
		panic_printf(", bfar = %x", CPU_NVIC_BFAR);
	if (mmfs & CPU_NVIC_MMFS_MFARVALID)
		panic_printf(", mfar = %x", CPU_NVIC_MFAR);
	panic_putc('\n');
	panic_printf("mmfs = %x, ", mmfs);
	panic_printf("shcsr = %x, ", CPU_NVIC_SHCSR);
	panic_printf("hfsr = %x, ", CPU_NVIC_HFSR);
	panic_printf("dfsr = %x", CPU_NVIC_DFSR);
}
#endif /* CONFIG_PANIC_HELP */


/**
 * Display a message and reboot
 */
static void panic_reboot(void)
{
	panic_puts("\n\nRebooting...\n");
	system_reset(0);
}


void report_panic(const char *msg, uint32_t *lregs)
{
	if (msg) {
		panic_printf("\n** PANIC: %s\n", msg);
	} else if (lregs) {
		uint32_t *sregs = NULL;
		uint32_t psp;
		int i;

		psp = lregs[0];
		if (psp >= CONFIG_RAM_BASE
				&& psp < CONFIG_RAM_BASE + CONFIG_RAM_SIZE)
			sregs = (uint32_t *)psp;
		panic_printf("\n=== EXCEPTION: %2x ====== xPSR: %8x "
			"===========\n", lregs[1] & 7, sregs ? sregs[7] : -1);
		for (i = 0; i < 4; i++)
			print_reg(i, sregs, i);
		for (i = 4; i < 10; i++)
			print_reg(i, lregs, i - 1);
		print_reg(10, lregs, 9);
		print_reg(11, lregs, 10);
		print_reg(12, sregs, 4);
		print_reg(13, &psp, 0);
		print_reg(14, sregs, 5);
		print_reg(15, sregs, 6);
#ifdef CONFIG_PANIC_HELP
		panic_show_extra();
#endif
	}

	panic_reboot();
}

/* Default exception handler, which reports a panic */
void exception_panic(void) __attribute__((naked));
void exception_panic(void)
{
	/* Naked call so we can extract raw LR and IPSR */
	asm volatile(
		/*
		 * This instruction will generate ldr rx, [pc, #offset]
		 * followed by a mov r0, rx. It would clearly be better if
		 * we could get ldr r0, [pc, #offset] but that doesn't seem
		 * to be supported. Nor does gcc seem to define which
		 * temporary register it uses. Therefore we put this
		 * instruction first so that it matters less.
		 *
		 * If you see a failure in the panic handler, please check
		 * the final assembler output here.
		 */
		"mov r0, %[save_area]\n"
		"mrs r1, psp\n"
		"mrs r2, ipsr\n"
		"mov r3, lr\n"
		"stmia r0, {r1-r11}\n"
#ifdef CONFIG_PANIC_NEW_STACK
		"mov sp, r0\n"
#endif
		"mov r1, r0\n"
		"mov r0, #0\n"
		"b report_panic" : :
			[save_area] "r" (save_area.saved_regs)
		);
}