arch/mips/kernel/kgdb.c

/*
 *  Originally written by Glenn Engel, Lake Stevens Instrument Division
 *
 *  Contributed by HP Systems
 *
 *  Modified for Linux/MIPS (and MIPS in general) by Andreas Busse
 *  Send complaints, suggestions etc. to <andy@waldorf-gmbh.de>
 *
 *  Copyright (C) 1995 Andreas Busse
 *
 *  Copyright (C) 2003 MontaVista Software Inc.
 *  Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
 *
 *  Copyright (C) 2004-2005 MontaVista Software Inc.
 *  Author: Manish Lachwani, mlachwani@mvista.com or manish@koffee-break.com
 *
 *  Copyright (C) 2007-2008 Wind River Systems, Inc.
 *  Author/Maintainer: Jason Wessel, jason.wessel@windriver.com
 *
 *  This file is licensed under the terms of the GNU General Public License
 *  version 2. This program is licensed "as is" without any warranty of any
 *  kind, whether express or implied.
 */

#include <linux/ptrace.h>		/* for linux pt_regs struct */
#include <linux/kgdb.h>
#include <linux/kdebug.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <asm/inst.h>
#include <asm/fpu.h>
#include <asm/cacheflush.h>
#include <asm/processor.h>
#include <asm/sigcontext.h>
#include <asm/uaccess.h>

static struct hard_trap_info {
	unsigned char tt;	/* Trap type code for MIPS R3xxx and R4xxx */
	unsigned char signo;	/* Signal that we map this trap into */
} hard_trap_info[] = {
	{ 6, SIGBUS },		/* instruction bus error */
	{ 7, SIGBUS },		/* data bus error */
	{ 9, SIGTRAP },		/* break */
/*	{ 11, SIGILL }, */	/* CPU unusable */
	{ 12, SIGFPE },		/* overflow */
	{ 13, SIGTRAP },	/* trap */
	{ 14, SIGSEGV },	/* virtual instruction cache coherency */
	{ 15, SIGFPE },		/* floating point exception */
	{ 23, SIGSEGV },	/* watch */
	{ 31, SIGSEGV },	/* virtual data cache coherency */
	{ 0, 0}			/* Must be last */
};

struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
{
	{ "zero", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) },
	{ "at", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) },
	{ "v0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) },
	{ "v1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) },
	{ "a0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) },
	{ "a1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) },
	{ "a2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) },
	{ "a3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) },
	{ "t0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) },
	{ "t1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) },
	{ "t2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) },
	{ "t3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) },
	{ "t4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) },
	{ "t5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) },
	{ "t6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) },
	{ "t7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) },
	{ "s0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16]) },
	{ "s1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17]) },
	{ "s2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18]) },
	{ "s3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19]) },
	{ "s4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20]) },
	{ "s5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21]) },
	{ "s6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22]) },
	{ "s7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23]) },
	{ "t8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24]) },
	{ "t9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25]) },
	{ "k0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26]) },
	{ "k1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27]) },
	{ "gp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28]) },
	{ "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29]) },
	{ "s8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30]) },
	{ "ra", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31]) },
	{ "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_status) },
	{ "lo", GDB_SIZEOF_REG, offsetof(struct pt_regs, lo) },
	{ "hi", GDB_SIZEOF_REG, offsetof(struct pt_regs, hi) },
	{ "bad", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_badvaddr) },
	{ "cause", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_cause) },
	{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_epc) },
	{ "f0", GDB_SIZEOF_REG, 0 },
	{ "f1", GDB_SIZEOF_REG, 1 },
	{ "f2", GDB_SIZEOF_REG, 2 },
	{ "f3", GDB_SIZEOF_REG, 3 },
	{ "f4", GDB_SIZEOF_REG, 4 },
	{ "f5", GDB_SIZEOF_REG, 5 },
	{ "f6", GDB_SIZEOF_REG, 6 },
	{ "f7", GDB_SIZEOF_REG, 7 },
	{ "f8", GDB_SIZEOF_REG, 8 },
	{ "f9", GDB_SIZEOF_REG, 9 },
	{ "f10", GDB_SIZEOF_REG, 10 },
	{ "f11", GDB_SIZEOF_REG, 11 },
	{ "f12", GDB_SIZEOF_REG, 12 },
	{ "f13", GDB_SIZEOF_REG, 13 },
	{ "f14", GDB_SIZEOF_REG, 14 },
	{ "f15", GDB_SIZEOF_REG, 15 },
	{ "f16", GDB_SIZEOF_REG, 16 },
	{ "f17", GDB_SIZEOF_REG, 17 },
	{ "f18", GDB_SIZEOF_REG, 18 },
	{ "f19", GDB_SIZEOF_REG, 19 },
	{ "f20", GDB_SIZEOF_REG, 20 },
	{ "f21", GDB_SIZEOF_REG, 21 },
	{ "f22", GDB_SIZEOF_REG, 22 },
	{ "f23", GDB_SIZEOF_REG, 23 },
	{ "f24", GDB_SIZEOF_REG, 24 },
	{ "f25", GDB_SIZEOF_REG, 25 },
	{ "f26", GDB_SIZEOF_REG, 26 },
	{ "f27", GDB_SIZEOF_REG, 27 },
	{ "f28", GDB_SIZEOF_REG, 28 },
	{ "f29", GDB_SIZEOF_REG, 29 },
	{ "f30", GDB_SIZEOF_REG, 30 },
	{ "f31", GDB_SIZEOF_REG, 31 },
	{ "fsr", GDB_SIZEOF_REG, 0 },
	{ "fir", GDB_SIZEOF_REG, 0 },
};

int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
	int fp_reg;

	if (regno < 0 || regno >= DBG_MAX_REG_NUM)
		return -EINVAL;

	if (dbg_reg_def[regno].offset != -1 && regno < 38) {
		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
		       dbg_reg_def[regno].size);
	} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
		/* FP registers 38 -> 69 */
		if (!(regs->cp0_status & ST0_CU1))
			return 0;
		if (regno == 70) {
			/* Process the fcr31/fsr (register 70) */
			memcpy((void *)&current->thread.fpu.fcr31, mem,
			       dbg_reg_def[regno].size);
			goto out_save;
		} else if (regno == 71) {
			/* Ignore the fir (register 71) */
			goto out_save;
		}
		fp_reg = dbg_reg_def[regno].offset;
		memcpy((void *)&current->thread.fpu.fpr[fp_reg], mem,
		       dbg_reg_def[regno].size);
out_save:
		restore_fp(current);
	}

	return 0;
}

char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
	int fp_reg;

	if (regno >= DBG_MAX_REG_NUM || regno < 0)
		return NULL;

	if (dbg_reg_def[regno].offset != -1 && regno < 38) {
		/* First 38 registers */
		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
		       dbg_reg_def[regno].size);
	} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
		/* FP registers 38 -> 69 */
		if (!(regs->cp0_status & ST0_CU1))
			goto out;
		save_fp(current);
		if (regno == 70) {
			/* Process the fcr31/fsr (register 70) */
			memcpy(mem, (void *)&current->thread.fpu.fcr31,
			       dbg_reg_def[regno].size);
			goto out;
		} else if (regno == 71) {
			/* Ignore the fir (register 71) */
			memset(mem, 0, dbg_reg_def[regno].size);
			goto out;
		}
		fp_reg = dbg_reg_def[regno].offset;
		memcpy(mem, (void *)&current->thread.fpu.fpr[fp_reg],
		       dbg_reg_def[regno].size);
	}

out:
	return dbg_reg_def[regno].name;

}

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

static void kgdb_call_nmi_hook(void *ignored)
{
	mm_segment_t old_fs;

	old_fs = get_fs();
	set_fs(get_ds());

	kgdb_nmicallback(raw_smp_processor_id(), NULL);

	set_fs(old_fs);
}

void kgdb_roundup_cpus(unsigned long flags)
{
	local_irq_enable();
	smp_call_function(kgdb_call_nmi_hook, NULL, 0);
	local_irq_disable();
}

static int compute_signal(int tt)
{
	struct hard_trap_info *ht;

	for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
		if (ht->tt == tt)
			return ht->signo;

	return SIGHUP;		/* default for things we don't know about */
}

/*
 * Similar to regs_to_gdb_regs() except that process is sleeping and so
 * we may not be able to get all the info.
 */
void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
	int reg;
#if (KGDB_GDB_REG_SIZE == 32)
	u32 *ptr = (u32 *)gdb_regs;
#else
	u64 *ptr = (u64 *)gdb_regs;
#endif

	for (reg = 0; reg < 16; reg++)
		*(ptr++) = 0;

	/* S0 - S7 */
	*(ptr++) = p->thread.reg16;
	*(ptr++) = p->thread.reg17;
	*(ptr++) = p->thread.reg18;
	*(ptr++) = p->thread.reg19;
	*(ptr++) = p->thread.reg20;
	*(ptr++) = p->thread.reg21;
	*(ptr++) = p->thread.reg22;
	*(ptr++) = p->thread.reg23;

	for (reg = 24; reg < 28; reg++)
		*(ptr++) = 0;

	/* GP, SP, FP, RA */
	*(ptr++) = (long)p;
	*(ptr++) = p->thread.reg29;
	*(ptr++) = p->thread.reg30;
	*(ptr++) = p->thread.reg31;

	*(ptr++) = p->thread.cp0_status;

	/* lo, hi */
	*(ptr++) = 0;
	*(ptr++) = 0;

	/*
	 * BadVAddr, Cause
	 * Ideally these would come from the last exception frame up the stack
	 * but that requires unwinding, otherwise we can't know much for sure.
	 */
	*(ptr++) = 0;
	*(ptr++) = 0;

	/*
	 * PC
	 * use return address (RA), i.e. the moment after return from resume()
	 */
	*(ptr++) = p->thread.reg31;
}

void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
	regs->cp0_epc = pc;
}

/*
 * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
 * then try to fall into the debugger
 */
static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
			    void *ptr)
{
	struct die_args *args = (struct die_args *)ptr;
	struct pt_regs *regs = args->regs;
	int trap = (regs->cp0_cause & 0x7c) >> 2;
	mm_segment_t old_fs;

#ifdef CONFIG_KPROBES
	/*
	 * Return immediately if the kprobes fault notifier has set
	 * DIE_PAGE_FAULT.
	 */
	if (cmd == DIE_PAGE_FAULT)
		return NOTIFY_DONE;
#endif /* CONFIG_KPROBES */

	/* Userspace events, ignore. */
	if (user_mode(regs))
		return NOTIFY_DONE;

	/* Kernel mode. Set correct address limit */
	old_fs = get_fs();
	set_fs(get_ds());

	if (atomic_read(&kgdb_active) != -1)
		kgdb_nmicallback(smp_processor_id(), regs);

	if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs)) {
		set_fs(old_fs);
		return NOTIFY_DONE;
	}

	if (atomic_read(&kgdb_setting_breakpoint))
		if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst))
			regs->cp0_epc += 4;

	/* In SMP mode, __flush_cache_all does IPI */
	local_irq_enable();
	__flush_cache_all();

	set_fs(old_fs);
	return NOTIFY_STOP;
}

#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
int kgdb_ll_trap(int cmd, const char *str,
		 struct pt_regs *regs, long err, int trap, int sig)
{
	struct die_args args = {
		.regs	= regs,
		.str	= str,
		.err	= err,
		.trapnr = trap,
		.signr	= sig,

	};

	if (!kgdb_io_module_registered)
		return NOTIFY_DONE;

	return kgdb_mips_notify(NULL, cmd, &args);
}
#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */

static struct notifier_block kgdb_notifier = {
	.notifier_call = kgdb_mips_notify,
};

/*
 * Handle the 'c' command
 */
int kgdb_arch_handle_exception(int vector, int signo, int err_code,
			       char *remcom_in_buffer, char *remcom_out_buffer,
			       struct pt_regs *regs)
{
	char *ptr;
	unsigned long address;

	switch (remcom_in_buffer[0]) {
	case 'c':
		/* handle the optional parameter */
		ptr = &remcom_in_buffer[1];
		if (kgdb_hex2long(&ptr, &address))
			regs->cp0_epc = address;

		return 0;
	}

	return -1;
}

struct kgdb_arch arch_kgdb_ops;

int kgdb_arch_init(void)
{
	union mips_instruction insn = {
		.r_format = {
			.opcode = spec_op,
			.func	= break_op,
		}
	};
	memcpy(arch_kgdb_ops.gdb_bpt_instr, insn.byte, BREAK_INSTR_SIZE);

	register_die_notifier(&kgdb_notifier);

	return 0;
}

/*
 *	kgdb_arch_exit - Perform any architecture specific uninitalization.
 *
 *	This function will handle the uninitalization of any architecture
 *	specific callbacks, for dynamic registration and unregistration.
 */
void kgdb_arch_exit(void)
{
	unregister_die_notifier(&kgdb_notifier);
}