/*
 *  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>

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 */
};

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)
{
        kgdb_nmicallback(raw_smp_processor_id(), NULL);
}

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 */
}

void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
        int reg;

#if (KGDB_GDB_REG_SIZE == 32)
        u32 *ptr = (u32 *)gdb_regs;
#else
        u64 *ptr = (u64 *)gdb_regs;
#endif

        for (reg = 0; reg < 32; reg++)
                *(ptr++) = regs->regs[reg];

        *(ptr++) = regs->cp0_status;
        *(ptr++) = regs->lo;
        *(ptr++) = regs->hi;
        *(ptr++) = regs->cp0_badvaddr;
        *(ptr++) = regs->cp0_cause;
        *(ptr++) = regs->cp0_epc;

        /* FP REGS */
        if (!(current && (regs->cp0_status & ST0_CU1)))
                return;

        save_fp(current);
        for (reg = 0; reg < 32; reg++)
                *(ptr++) = current->thread.fpu.fpr[reg];
}

void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
        int reg;

#if (KGDB_GDB_REG_SIZE == 32)
        const u32 *ptr = (u32 *)gdb_regs;
#else
        const u64 *ptr = (u64 *)gdb_regs;
#endif

        for (reg = 0; reg < 32; reg++)
                regs->regs[reg] = *(ptr++);

        regs->cp0_status = *(ptr++);
        regs->lo = *(ptr++);
        regs->hi = *(ptr++);
        regs->cp0_badvaddr = *(ptr++);
        regs->cp0_cause = *(ptr++);
        regs->cp0_epc = *(ptr++);

        /* FP REGS from current */
        if (!(current && (regs->cp0_status & ST0_CU1)))
                return;

        for (reg = 0; reg < 32; reg++)
                current->thread.fpu.fpr[reg] = *(ptr++);
        restore_fp(current);
}

/*
 * 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;
        struct thread_info *ti = task_thread_info(p);
        unsigned long ksp = (unsigned long)ti + THREAD_SIZE - 32;
        struct pt_regs *regs = (struct pt_regs *)ksp - 1;
#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++) = regs->regs[reg];

        /* S0 - S7 */
        for (reg = 16; reg < 24; reg++)
                *(ptr++) = regs->regs[reg];

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

        /* GP, SP, FP, RA */
        for (reg = 28; reg < 32; reg++)
                *(ptr++) = regs->regs[reg];

        *(ptr++) = regs->cp0_status;
        *(ptr++) = regs->lo;
        *(ptr++) = regs->hi;
        *(ptr++) = regs->cp0_badvaddr;
        *(ptr++) = regs->cp0_cause;
        *(ptr++) = regs->cp0_epc;
}

/*
 * 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;

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

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

        if (kgdb_handle_exception(trap, compute_signal(trap), 0, regs))
                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();

        return NOTIFY_STOP;
}

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

/*
 * Handle the 's' and 'c' commands
 */
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;
        int cpu = smp_processor_id();

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

                atomic_set(&kgdb_cpu_doing_single_step, -1);
                if (remcom_in_buffer[0] == 's')
                        atomic_set(&kgdb_cpu_doing_single_step, cpu);

                return 0;
        }

        return -1;
}

struct kgdb_arch arch_kgdb_ops;

/*
 * We use kgdb_early_setup so that functions we need to call now don't
 * cause trouble when called again later.
 */
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);
}