/*
 * HW exception handling
 *
 * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2008 PetaLogix
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of this
 * archive for more details.
 */

/*
 * This file handles the architecture-dependent parts of hardware exceptions
 */

#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/kallsyms.h>

#include <asm/exceptions.h>
#include <asm/entry.h>          /* For KM CPU var */
#include <linux/uaccess.h>
#include <linux/errno.h>
#include <linux/ptrace.h>
#include <asm/current.h>
#include <asm/cacheflush.h>

#define MICROBLAZE_ILL_OPCODE_EXCEPTION 0x02
#define MICROBLAZE_IBUS_EXCEPTION       0x03
#define MICROBLAZE_DBUS_EXCEPTION       0x04
#define MICROBLAZE_DIV_ZERO_EXCEPTION   0x05
#define MICROBLAZE_FPU_EXCEPTION        0x06
#define MICROBLAZE_PRIVILEGED_EXCEPTION 0x07

static DEFINE_SPINLOCK(die_lock);

void die(const char *str, struct pt_regs *fp, long err)
{
        console_verbose();
        spin_lock_irq(&die_lock);
        pr_warn("Oops: %s, sig: %ld\n", str, err);
        show_regs(fp);
        spin_unlock_irq(&die_lock);
        /* make_task_dead() should take care of panic'ing from an interrupt
         * context so we don't handle it here
         */
        make_task_dead(err);
}

/* for user application debugging */
asmlinkage void sw_exception(struct pt_regs *regs)
{
        _exception(SIGTRAP, regs, TRAP_BRKPT, regs->r16);
        flush_dcache_range(regs->r16, regs->r16 + 0x4);
        flush_icache_range(regs->r16, regs->r16 + 0x4);
}

void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
{
        if (kernel_mode(regs))
                die("Exception in kernel mode", regs, signr);

        force_sig_fault(signr, code, (void __user *)addr);
}

asmlinkage void full_exception(struct pt_regs *regs, unsigned int type,
                                                        int fsr, int addr)
{
        addr = regs->pc;

#if 0
        pr_warn("Exception %02x in %s mode, FSR=%08x PC=%08x ESR=%08x\n",
                        type, user_mode(regs) ? "user" : "kernel", fsr,
                        (unsigned int) regs->pc, (unsigned int) regs->esr);
#endif

        switch (type & 0x1F) {
        case MICROBLAZE_ILL_OPCODE_EXCEPTION:
                if (user_mode(regs)) {
                        pr_debug("Illegal opcode exception in user mode\n");
                        _exception(SIGILL, regs, ILL_ILLOPC, addr);
                        return;
                }
                pr_warn("Illegal opcode exception in kernel mode.\n");
                die("opcode exception", regs, SIGBUS);
                break;
        case MICROBLAZE_IBUS_EXCEPTION:
                if (user_mode(regs)) {
                        pr_debug("Instruction bus error exception in user mode\n");
                        _exception(SIGBUS, regs, BUS_ADRERR, addr);
                        return;
                }
                pr_warn("Instruction bus error exception in kernel mode.\n");
                die("bus exception", regs, SIGBUS);
                break;
        case MICROBLAZE_DBUS_EXCEPTION:
                if (user_mode(regs)) {
                        pr_debug("Data bus error exception in user mode\n");
                        _exception(SIGBUS, regs, BUS_ADRERR, addr);
                        return;
                }
                pr_warn("Data bus error exception in kernel mode.\n");
                die("bus exception", regs, SIGBUS);
                break;
        case MICROBLAZE_DIV_ZERO_EXCEPTION:
                if (user_mode(regs)) {
                        pr_debug("Divide by zero exception in user mode\n");
                        _exception(SIGFPE, regs, FPE_INTDIV, addr);
                        return;
                }
                pr_warn("Divide by zero exception in kernel mode.\n");
                die("Divide by zero exception", regs, SIGBUS);
                break;
        case MICROBLAZE_FPU_EXCEPTION:
                pr_debug("FPU exception\n");
                /* IEEE FP exception */
                /* I removed fsr variable and use code var for storing fsr */
                if (fsr & FSR_IO)
                        fsr = FPE_FLTINV;
                else if (fsr & FSR_OF)
                        fsr = FPE_FLTOVF;
                else if (fsr & FSR_UF)
                        fsr = FPE_FLTUND;
                else if (fsr & FSR_DZ)
                        fsr = FPE_FLTDIV;
                else if (fsr & FSR_DO)
                        fsr = FPE_FLTRES;
                _exception(SIGFPE, regs, fsr, addr);
                break;
        case MICROBLAZE_PRIVILEGED_EXCEPTION:
                pr_debug("Privileged exception\n");
                _exception(SIGILL, regs, ILL_PRVOPC, addr);
                break;
        default:
        /* FIXME what to do in unexpected exception */
                pr_warn("Unexpected exception %02x PC=%08x in %s mode\n",
                        type, (unsigned int) addr,
                        kernel_mode(regs) ? "kernel" : "user");
        }
        return;
}