// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (C) 1995-1996  Gary Thomas (gdt@linuxppc.org)
 *  Copyright 2007-2010 Freescale Semiconductor, Inc.
 *
 *  Modified by Cort Dougan (cort@cs.nmt.edu)
 *  and Paul Mackerras (paulus@samba.org)
 */

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

#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pkeys.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/extable.h>
#include <linux/module.h>       /* print_modules */
#include <linux/prctl.h>
#include <linux/delay.h>
#include <linux/kprobes.h>
#include <linux/kexec.h>
#include <linux/backlight.h>
#include <linux/bug.h>
#include <linux/kdebug.h>
#include <linux/ratelimit.h>
#include <linux/context_tracking.h>
#include <linux/smp.h>
#include <linux/console.h>
#include <linux/kmsg_dump.h>

#include <asm/emulated_ops.h>
#include <linux/uaccess.h>
#include <asm/debugfs.h>
#include <asm/interrupt.h>
#include <asm/io.h>
#include <asm/machdep.h>
#include <asm/rtas.h>
#include <asm/pmc.h>
#include <asm/reg.h>
#ifdef CONFIG_PMAC_BACKLIGHT
#include <asm/backlight.h>
#endif
#ifdef CONFIG_PPC64
#include <asm/firmware.h>
#include <asm/processor.h>
#endif
#include <asm/kexec.h>
#include <asm/ppc-opcode.h>
#include <asm/rio.h>
#include <asm/fadump.h>
#include <asm/switch_to.h>
#include <asm/tm.h>
#include <asm/debug.h>
#include <asm/asm-prototypes.h>
#include <asm/hmi.h>
#include <sysdev/fsl_pci.h>
#include <asm/kprobes.h>
#include <asm/stacktrace.h>
#include <asm/nmi.h>
#include <asm/disassemble.h>

#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC_CORE)
int (*__debugger)(struct pt_regs *regs) __read_mostly;
int (*__debugger_ipi)(struct pt_regs *regs) __read_mostly;
int (*__debugger_bpt)(struct pt_regs *regs) __read_mostly;
int (*__debugger_sstep)(struct pt_regs *regs) __read_mostly;
int (*__debugger_iabr_match)(struct pt_regs *regs) __read_mostly;
int (*__debugger_break_match)(struct pt_regs *regs) __read_mostly;
int (*__debugger_fault_handler)(struct pt_regs *regs) __read_mostly;

EXPORT_SYMBOL(__debugger);
EXPORT_SYMBOL(__debugger_ipi);
EXPORT_SYMBOL(__debugger_bpt);
EXPORT_SYMBOL(__debugger_sstep);
EXPORT_SYMBOL(__debugger_iabr_match);
EXPORT_SYMBOL(__debugger_break_match);
EXPORT_SYMBOL(__debugger_fault_handler);
#endif

/* Transactional Memory trap debug */
#ifdef TM_DEBUG_SW
#define TM_DEBUG(x...) printk(KERN_INFO x)
#else
#define TM_DEBUG(x...) do { } while(0)
#endif

static const char *signame(int signr)
{
        switch (signr) {
        case SIGBUS:    return "bus error";
        case SIGFPE:    return "floating point exception";
        case SIGILL:    return "illegal instruction";
        case SIGSEGV:   return "segfault";
        case SIGTRAP:   return "unhandled trap";
        }

        return "unknown signal";
}

/*
 * Trap & Exception support
 */

#ifdef CONFIG_PMAC_BACKLIGHT
static void pmac_backlight_unblank(void)
{
        mutex_lock(&pmac_backlight_mutex);
        if (pmac_backlight) {
                struct backlight_properties *props;

                props = &pmac_backlight->props;
                props->brightness = props->max_brightness;
                props->power = FB_BLANK_UNBLANK;
                backlight_update_status(pmac_backlight);
        }
        mutex_unlock(&pmac_backlight_mutex);
}
#else
static inline void pmac_backlight_unblank(void) { }
#endif

/*
 * If oops/die is expected to crash the machine, return true here.
 *
 * This should not be expected to be 100% accurate, there may be
 * notifiers registered or other unexpected conditions that may bring
 * down the kernel. Or if the current process in the kernel is holding
 * locks or has other critical state, the kernel may become effectively
 * unusable anyway.
 */
bool die_will_crash(void)
{
        if (should_fadump_crash())
                return true;
        if (kexec_should_crash(current))
                return true;
        if (in_interrupt() || panic_on_oops ||
                        !current->pid || is_global_init(current))
                return true;

        return false;
}

static arch_spinlock_t die_lock = __ARCH_SPIN_LOCK_UNLOCKED;
static int die_owner = -1;
static unsigned int die_nest_count;
static int die_counter;

extern void panic_flush_kmsg_start(void)
{
        /*
         * These are mostly taken from kernel/panic.c, but tries to do
         * relatively minimal work. Don't use delay functions (TB may
         * be broken), don't crash dump (need to set a firmware log),
         * don't run notifiers. We do want to get some information to
         * Linux console.
         */
        console_verbose();
        bust_spinlocks(1);
}

extern void panic_flush_kmsg_end(void)
{
        printk_safe_flush_on_panic();
        kmsg_dump(KMSG_DUMP_PANIC);
        bust_spinlocks(0);
        debug_locks_off();
        console_flush_on_panic(CONSOLE_FLUSH_PENDING);
}

static unsigned long oops_begin(struct pt_regs *regs)
{
        int cpu;
        unsigned long flags;

        oops_enter();

        /* racy, but better than risking deadlock. */
        raw_local_irq_save(flags);
        cpu = smp_processor_id();
        if (!arch_spin_trylock(&die_lock)) {
                if (cpu == die_owner)
                        /* nested oops. should stop eventually */;
                else
                        arch_spin_lock(&die_lock);
        }
        die_nest_count++;
        die_owner = cpu;
        console_verbose();
        bust_spinlocks(1);
        if (machine_is(powermac))
                pmac_backlight_unblank();
        return flags;
}
NOKPROBE_SYMBOL(oops_begin);

static void oops_end(unsigned long flags, struct pt_regs *regs,
                               int signr)
{
        bust_spinlocks(0);
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
        die_nest_count--;
        oops_exit();
        printk("\n");
        if (!die_nest_count) {
                /* Nest count reaches zero, release the lock. */
                die_owner = -1;
                arch_spin_unlock(&die_lock);
        }
        raw_local_irq_restore(flags);

        /*
         * system_reset_excption handles debugger, crash dump, panic, for 0x100
         */
        if (TRAP(regs) == INTERRUPT_SYSTEM_RESET)
                return;

        crash_fadump(regs, "die oops");

        if (kexec_should_crash(current))
                crash_kexec(regs);

        if (!signr)
                return;

        /*
         * While our oops output is serialised by a spinlock, output
         * from panic() called below can race and corrupt it. If we
         * know we are going to panic, delay for 1 second so we have a
         * chance to get clean backtraces from all CPUs that are oopsing.
         */
        if (in_interrupt() || panic_on_oops || !current->pid ||
            is_global_init(current)) {
                mdelay(MSEC_PER_SEC);
        }

        if (panic_on_oops)
                panic("Fatal exception");
        do_exit(signr);
}
NOKPROBE_SYMBOL(oops_end);

static char *get_mmu_str(void)
{
        if (early_radix_enabled())
                return " MMU=Radix";
        if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
                return " MMU=Hash";
        return "";
}

static int __die(const char *str, struct pt_regs *regs, long err)
{
        printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);

        printk("%s PAGE_SIZE=%luK%s%s%s%s%s%s %s\n",
               IS_ENABLED(CONFIG_CPU_LITTLE_ENDIAN) ? "LE" : "BE",
               PAGE_SIZE / 1024, get_mmu_str(),
               IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
               IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
               IS_ENABLED(CONFIG_SMP) ? (" NR_CPUS=" __stringify(NR_CPUS)) : "",
               debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
               IS_ENABLED(CONFIG_NUMA) ? " NUMA" : "",
               ppc_md.name ? ppc_md.name : "");

        if (notify_die(DIE_OOPS, str, regs, err, 255, SIGSEGV) == NOTIFY_STOP)
                return 1;

        print_modules();
        show_regs(regs);

        return 0;
}
NOKPROBE_SYMBOL(__die);

void die(const char *str, struct pt_regs *regs, long err)
{
        unsigned long flags;

        /*
         * system_reset_excption handles debugger, crash dump, panic, for 0x100
         */
        if (TRAP(regs) != INTERRUPT_SYSTEM_RESET) {
                if (debugger(regs))
                        return;
        }

        flags = oops_begin(regs);
        if (__die(str, regs, err))
                err = 0;
        oops_end(flags, regs, err);
}
NOKPROBE_SYMBOL(die);

void user_single_step_report(struct pt_regs *regs)
{
        force_sig_fault(SIGTRAP, TRAP_TRACE, (void __user *)regs->nip);
}

static void show_signal_msg(int signr, struct pt_regs *regs, int code,
                            unsigned long addr)
{
        static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
                                      DEFAULT_RATELIMIT_BURST);

        if (!show_unhandled_signals)
                return;

        if (!unhandled_signal(current, signr))
                return;

        if (!__ratelimit(&rs))
                return;

        pr_info("%s[%d]: %s (%d) at %lx nip %lx lr %lx code %x",
                current->comm, current->pid, signame(signr), signr,
                addr, regs->nip, regs->link, code);

        print_vma_addr(KERN_CONT " in ", regs->nip);

        pr_cont("\n");

        show_user_instructions(regs);
}

static bool exception_common(int signr, struct pt_regs *regs, int code,
                              unsigned long addr)
{
        if (!user_mode(regs)) {
                die("Exception in kernel mode", regs, signr);
                return false;
        }

        show_signal_msg(signr, regs, code, addr);

        if (arch_irqs_disabled())
                interrupt_cond_local_irq_enable(regs);

        current->thread.trap_nr = code;

        return true;
}

void _exception_pkey(struct pt_regs *regs, unsigned long addr, int key)
{
        if (!exception_common(SIGSEGV, regs, SEGV_PKUERR, addr))
                return;

        force_sig_pkuerr((void __user *) addr, key);
}

void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
{
        if (!exception_common(signr, regs, code, addr))
                return;

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

/*
 * The interrupt architecture has a quirk in that the HV interrupts excluding
 * the NMIs (0x100 and 0x200) do not clear MSR[RI] at entry. The first thing
 * that an interrupt handler must do is save off a GPR into a scratch register,
 * and all interrupts on POWERNV (HV=1) use the HSPRG1 register as scratch.
 * Therefore an NMI can clobber an HV interrupt's live HSPRG1 without noticing
 * that it is non-reentrant, which leads to random data corruption.
 *
 * The solution is for NMI interrupts in HV mode to check if they originated
 * from these critical HV interrupt regions. If so, then mark them not
 * recoverable.
 *
 * An alternative would be for HV NMIs to use SPRG for scratch to avoid the
 * HSPRG1 clobber, however this would cause guest SPRG to be clobbered. Linux
 * guests should always have MSR[RI]=0 when its scratch SPRG is in use, so
 * that would work. However any other guest OS that may have the SPRG live
 * and MSR[RI]=1 could encounter silent corruption.
 *
 * Builds that do not support KVM could take this second option to increase
 * the recoverability of NMIs.
 */
void hv_nmi_check_nonrecoverable(struct pt_regs *regs)
{
#ifdef CONFIG_PPC_POWERNV
        unsigned long kbase = (unsigned long)_stext;
        unsigned long nip = regs->nip;

        if (!(regs->msr & MSR_RI))
                return;
        if (!(regs->msr & MSR_HV))
                return;
        if (regs->msr & MSR_PR)
                return;

        /*
         * Now test if the interrupt has hit a range that may be using
         * HSPRG1 without having RI=0 (i.e., an HSRR interrupt). The
         * problem ranges all run un-relocated. Test real and virt modes
         * at the same time by dropping the high bit of the nip (virt mode
         * entry points still have the +0x4000 offset).
         */
        nip &= ~0xc000000000000000ULL;
        if ((nip >= 0x500 && nip < 0x600) || (nip >= 0x4500 && nip < 0x4600))
                goto nonrecoverable;
        if ((nip >= 0x980 && nip < 0xa00) || (nip >= 0x4980 && nip < 0x4a00))
                goto nonrecoverable;
        if ((nip >= 0xe00 && nip < 0xec0) || (nip >= 0x4e00 && nip < 0x4ec0))
                goto nonrecoverable;
        if ((nip >= 0xf80 && nip < 0xfa0) || (nip >= 0x4f80 && nip < 0x4fa0))
                goto nonrecoverable;

        /* Trampoline code runs un-relocated so subtract kbase. */
        if (nip >= (unsigned long)(start_real_trampolines - kbase) &&
                        nip < (unsigned long)(end_real_trampolines - kbase))
                goto nonrecoverable;
        if (nip >= (unsigned long)(start_virt_trampolines - kbase) &&
                        nip < (unsigned long)(end_virt_trampolines - kbase))
                goto nonrecoverable;
        return;

nonrecoverable:
        regs_set_return_msr(regs, regs->msr & ~MSR_RI);
#endif
}
DEFINE_INTERRUPT_HANDLER_NMI(system_reset_exception)
{
        unsigned long hsrr0, hsrr1;
        bool saved_hsrrs = false;

        /*
         * System reset can interrupt code where HSRRs are live and MSR[RI]=1.
         * The system reset interrupt itself may clobber HSRRs (e.g., to call
         * OPAL), so save them here and restore them before returning.
         *
         * Machine checks don't need to save HSRRs, as the real mode handler
         * is careful to avoid them, and the regular handler is not delivered
         * as an NMI.
         */
        if (cpu_has_feature(CPU_FTR_HVMODE)) {
                hsrr0 = mfspr(SPRN_HSRR0);
                hsrr1 = mfspr(SPRN_HSRR1);
                saved_hsrrs = true;
        }

        hv_nmi_check_nonrecoverable(regs);

        __this_cpu_inc(irq_stat.sreset_irqs);

        /* See if any machine dependent calls */
        if (ppc_md.system_reset_exception) {
                if (ppc_md.system_reset_exception(regs))
                        goto out;
        }

        if (debugger(regs))
                goto out;

        kmsg_dump(KMSG_DUMP_OOPS);
        /*
         * A system reset is a request to dump, so we always send
         * it through the crashdump code (if fadump or kdump are
         * registered).
         */
        crash_fadump(regs, "System Reset");

        crash_kexec(regs);

        /*
         * We aren't the primary crash CPU. We need to send it
         * to a holding pattern to avoid it ending up in the panic
         * code.
         */
        crash_kexec_secondary(regs);

        /*
         * No debugger or crash dump registered, print logs then
         * panic.
         */
        die("System Reset", regs, SIGABRT);

        mdelay(2*MSEC_PER_SEC); /* Wait a little while for others to print */
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
        nmi_panic(regs, "System Reset");

out:
#ifdef CONFIG_PPC_BOOK3S_64
        BUG_ON(get_paca()->in_nmi == 0);
        if (get_paca()->in_nmi > 1)
                die("Unrecoverable nested System Reset", regs, SIGABRT);
#endif
        /* Must die if the interrupt is not recoverable */
        if (!(regs->msr & MSR_RI)) {
                /* For the reason explained in die_mce, nmi_exit before die */
                nmi_exit();
                die("Unrecoverable System Reset", regs, SIGABRT);
        }

        if (saved_hsrrs) {
                mtspr(SPRN_HSRR0, hsrr0);
                mtspr(SPRN_HSRR1, hsrr1);
        }

        /* What should we do here? We could issue a shutdown or hard reset. */

        return 0;
}

/*
 * I/O accesses can cause machine checks on powermacs.
 * Check if the NIP corresponds to the address of a sync
 * instruction for which there is an entry in the exception
 * table.
 *  -- paulus.
 */
static inline int check_io_access(struct pt_regs *regs)
{
#ifdef CONFIG_PPC32
        unsigned long msr = regs->msr;
        const struct exception_table_entry *entry;
        unsigned int *nip = (unsigned int *)regs->nip;

        if (((msr & 0xffff0000) == 0 || (msr & (0x80000 | 0x40000)))
            && (entry = search_exception_tables(regs->nip)) != NULL) {
                /*
                 * Check that it's a sync instruction, or somewhere
                 * in the twi; isync; nop sequence that inb/inw/inl uses.
                 * As the address is in the exception table
                 * we should be able to read the instr there.
                 * For the debug message, we look at the preceding
                 * load or store.
                 */
                if (*nip == PPC_RAW_NOP())
                        nip -= 2;
                else if (*nip == PPC_RAW_ISYNC())
                        --nip;
                if (*nip == PPC_RAW_SYNC() || get_op(*nip) == OP_TRAP) {
                        unsigned int rb;

                        --nip;
                        rb = (*nip >> 11) & 0x1f;
                        printk(KERN_DEBUG "%s bad port %lx at %p\n",
                               (*nip & 0x100)? "OUT to": "IN from",
                               regs->gpr[rb] - _IO_BASE, nip);
                        regs_set_return_msr(regs, regs->msr | MSR_RI);
                        regs_set_return_ip(regs, extable_fixup(entry));
                        return 1;
                }
        }
#endif /* CONFIG_PPC32 */
        return 0;
}

#ifdef CONFIG_PPC_ADV_DEBUG_REGS
/* On 4xx, the reason for the machine check or program exception
   is in the ESR. */
#define get_reason(regs)        ((regs)->dsisr)
#define REASON_FP               ESR_FP
#define REASON_ILLEGAL          (ESR_PIL | ESR_PUO)
#define REASON_PRIVILEGED       ESR_PPR
#define REASON_TRAP             ESR_PTR
#define REASON_PREFIXED         0
#define REASON_BOUNDARY         0

/* single-step stuff */
#define single_stepping(regs)   (current->thread.debug.dbcr0 & DBCR0_IC)
#define clear_single_step(regs) (current->thread.debug.dbcr0 &= ~DBCR0_IC)
#define clear_br_trace(regs)    do {} while(0)
#else
/* On non-4xx, the reason for the machine check or program
   exception is in the MSR. */
#define get_reason(regs)        ((regs)->msr)
#define REASON_TM               SRR1_PROGTM
#define REASON_FP               SRR1_PROGFPE
#define REASON_ILLEGAL          SRR1_PROGILL
#define REASON_PRIVILEGED       SRR1_PROGPRIV
#define REASON_TRAP             SRR1_PROGTRAP
#define REASON_PREFIXED         SRR1_PREFIXED
#define REASON_BOUNDARY         SRR1_BOUNDARY

#define single_stepping(regs)   ((regs)->msr & MSR_SE)
#define clear_single_step(regs) (regs_set_return_msr((regs), (regs)->msr & ~MSR_SE))
#define clear_br_trace(regs)    (regs_set_return_msr((regs), (regs)->msr & ~MSR_BE))
#endif

#define inst_length(reason)     (((reason) & REASON_PREFIXED) ? 8 : 4)

#if defined(CONFIG_E500)
int machine_check_e500mc(struct pt_regs *regs)
{
        unsigned long mcsr = mfspr(SPRN_MCSR);
        unsigned long pvr = mfspr(SPRN_PVR);
        unsigned long reason = mcsr;
        int recoverable = 1;

        if (reason & MCSR_LD) {
                recoverable = fsl_rio_mcheck_exception(regs);
                if (recoverable == 1)
                        goto silent_out;
        }

        printk("Machine check in kernel mode.\n");
        printk("Caused by (from MCSR=%lx): ", reason);

        if (reason & MCSR_MCP)
                pr_cont("Machine Check Signal\n");

        if (reason & MCSR_ICPERR) {
                pr_cont("Instruction Cache Parity Error\n");

                /*
                 * This is recoverable by invalidating the i-cache.
                 */
                mtspr(SPRN_L1CSR1, mfspr(SPRN_L1CSR1) | L1CSR1_ICFI);
                while (mfspr(SPRN_L1CSR1) & L1CSR1_ICFI)
                        ;

                /*
                 * This will generally be accompanied by an instruction
                 * fetch error report -- only treat MCSR_IF as fatal
                 * if it wasn't due to an L1 parity error.
                 */
                reason &= ~MCSR_IF;
        }

        if (reason & MCSR_DCPERR_MC) {
                pr_cont("Data Cache Parity Error\n");

                /*
                 * In write shadow mode we auto-recover from the error, but it
                 * may still get logged and cause a machine check.  We should
                 * only treat the non-write shadow case as non-recoverable.
                 */
                /* On e6500 core, L1 DCWS (Data cache write shadow mode) bit
                 * is not implemented but L1 data cache always runs in write
                 * shadow mode. Hence on data cache parity errors HW will
                 * automatically invalidate the L1 Data Cache.
                 */
                if (PVR_VER(pvr) != PVR_VER_E6500) {
                        if (!(mfspr(SPRN_L1CSR2) & L1CSR2_DCWS))
                                recoverable = 0;
                }
        }

        if (reason & MCSR_L2MMU_MHIT) {
                pr_cont("Hit on multiple TLB entries\n");
                recoverable = 0;
        }

        if (reason & MCSR_NMI)
                pr_cont("Non-maskable interrupt\n");

        if (reason & MCSR_IF) {
                pr_cont("Instruction Fetch Error Report\n");
                recoverable = 0;
        }

        if (reason & MCSR_LD) {
                pr_cont("Load Error Report\n");
                recoverable = 0;
        }

        if (reason & MCSR_ST) {
                pr_cont("Store Error Report\n");
                recoverable = 0;
        }

        if (reason & MCSR_LDG) {
                pr_cont("Guarded Load Error Report\n");
                recoverable = 0;
        }

        if (reason & MCSR_TLBSYNC)
                pr_cont("Simultaneous tlbsync operations\n");

        if (reason & MCSR_BSL2_ERR) {
                pr_cont("Level 2 Cache Error\n");
                recoverable = 0;
        }

        if (reason & MCSR_MAV) {
                u64 addr;

                addr = mfspr(SPRN_MCAR);
                addr |= (u64)mfspr(SPRN_MCARU) << 32;

                pr_cont("Machine Check %s Address: %#llx\n",
                       reason & MCSR_MEA ? "Effective" : "Physical", addr);
        }

silent_out:
        mtspr(SPRN_MCSR, mcsr);
        return mfspr(SPRN_MCSR) == 0 && recoverable;
}

int machine_check_e500(struct pt_regs *regs)
{
        unsigned long reason = mfspr(SPRN_MCSR);

        if (reason & MCSR_BUS_RBERR) {
                if (fsl_rio_mcheck_exception(regs))
                        return 1;
                if (fsl_pci_mcheck_exception(regs))
                        return 1;
        }

        printk("Machine check in kernel mode.\n");
        printk("Caused by (from MCSR=%lx): ", reason);

        if (reason & MCSR_MCP)
                pr_cont("Machine Check Signal\n");
        if (reason & MCSR_ICPERR)
                pr_cont("Instruction Cache Parity Error\n");
        if (reason & MCSR_DCP_PERR)
                pr_cont("Data Cache Push Parity Error\n");
        if (reason & MCSR_DCPERR)
                pr_cont("Data Cache Parity Error\n");
        if (reason & MCSR_BUS_IAERR)
                pr_cont("Bus - Instruction Address Error\n");
        if (reason & MCSR_BUS_RAERR)
                pr_cont("Bus - Read Address Error\n");
        if (reason & MCSR_BUS_WAERR)
                pr_cont("Bus - Write Address Error\n");
        if (reason & MCSR_BUS_IBERR)
                pr_cont("Bus - Instruction Data Error\n");
        if (reason & MCSR_BUS_RBERR)
                pr_cont("Bus - Read Data Bus Error\n");
        if (reason & MCSR_BUS_WBERR)
                pr_cont("Bus - Write Data Bus Error\n");
        if (reason & MCSR_BUS_IPERR)
                pr_cont("Bus - Instruction Parity Error\n");
        if (reason & MCSR_BUS_RPERR)
                pr_cont("Bus - Read Parity Error\n");

        return 0;
}

int machine_check_generic(struct pt_regs *regs)
{
        return 0;
}
#elif defined(CONFIG_PPC32)
int machine_check_generic(struct pt_regs *regs)
{
        unsigned long reason = regs->msr;

        printk("Machine check in kernel mode.\n");
        printk("Caused by (from SRR1=%lx): ", reason);
        switch (reason & 0x601F0000) {
        case 0x80000:
                pr_cont("Machine check signal\n");
                break;
        case 0x40000:
        case 0x140000:  /* 7450 MSS error and TEA */
                pr_cont("Transfer error ack signal\n");
                break;
        case 0x20000:
                pr_cont("Data parity error signal\n");
                break;
        case 0x10000:
                pr_cont("Address parity error signal\n");
                break;
        case 0x20000000:
                pr_cont("L1 Data Cache error\n");
                break;
        case 0x40000000:
                pr_cont("L1 Instruction Cache error\n");
                break;
        case 0x00100000:
                pr_cont("L2 data cache parity error\n");
                break;
        default:
                pr_cont("Unknown values in msr\n");
        }
        return 0;
}
#endif /* everything else */

void die_mce(const char *str, struct pt_regs *regs, long err)
{
        /*
         * The machine check wants to kill the interrupted context, but
         * do_exit() checks for in_interrupt() and panics in that case, so
         * exit the irq/nmi before calling die.
         */
        if (IS_ENABLED(CONFIG_PPC_BOOK3S_64))
                irq_exit();
        else
                nmi_exit();
        die(str, regs, err);
}

/*
 * BOOK3S_64 does not call this handler as a non-maskable interrupt
 * (it uses its own early real-mode handler to handle the MCE proper
 * and then raises irq_work to call this handler when interrupts are
 * enabled).
 */
#ifdef CONFIG_PPC_BOOK3S_64
DEFINE_INTERRUPT_HANDLER_ASYNC(machine_check_exception)
#else
DEFINE_INTERRUPT_HANDLER_NMI(machine_check_exception)
#endif
{
        int recover = 0;

        __this_cpu_inc(irq_stat.mce_exceptions);

        add_taint(TAINT_MACHINE_CHECK, LOCKDEP_NOW_UNRELIABLE);

        /* See if any machine dependent calls. In theory, we would want
         * to call the CPU first, and call the ppc_md. one if the CPU
         * one returns a positive number. However there is existing code
         * that assumes the board gets a first chance, so let's keep it
         * that way for now and fix things later. --BenH.
         */
        if (ppc_md.machine_check_exception)
                recover = ppc_md.machine_check_exception(regs);
        else if (cur_cpu_spec->machine_check)
                recover = cur_cpu_spec->machine_check(regs);

        if (recover > 0)
                goto bail;

        if (debugger_fault_handler(regs))
                goto bail;

        if (check_io_access(regs))
                goto bail;

        die_mce("Machine check", regs, SIGBUS);

bail:
        /* Must die if the interrupt is not recoverable */
        if (!(regs->msr & MSR_RI))
                die_mce("Unrecoverable Machine check", regs, SIGBUS);

#ifdef CONFIG_PPC_BOOK3S_64
        return;
#else
        return 0;
#endif
}

DEFINE_INTERRUPT_HANDLER(SMIException) /* async? */
{
        die("System Management Interrupt", regs, SIGABRT);
}

#ifdef CONFIG_VSX
static void p9_hmi_special_emu(struct pt_regs *regs)
{
        unsigned int ra, rb, t, i, sel, instr, rc;
        const void __user *addr;
        u8 vbuf[16] __aligned(16), *vdst;
        unsigned long ea, msr, msr_mask;
        bool swap;

        if (__get_user(instr, (unsigned int __user *)regs->nip))
                return;

        /*
         * lxvb16x      opcode: 0x7c0006d8
         * lxvd2x       opcode: 0x7c000698
         * lxvh8x       opcode: 0x7c000658
         * lxvw4x       opcode: 0x7c000618
         */
        if ((instr & 0xfc00073e) != 0x7c000618) {
                pr_devel("HMI vec emu: not vector CI %i:%s[%d] nip=%016lx"
                         " instr=%08x\n",
                         smp_processor_id(), current->comm, current->pid,
                         regs->nip, instr);
                return;
        }

        /* Grab vector registers into the task struct */
        msr = regs->msr; /* Grab msr before we flush the bits */
        flush_vsx_to_thread(current);
        enable_kernel_altivec();

        /*
         * Is userspace running with a different endian (this is rare but
         * not impossible)
         */
        swap = (msr & MSR_LE) != (MSR_KERNEL & MSR_LE);

        /* Decode the instruction */
        ra = (instr >> 16) & 0x1f;
        rb = (instr >> 11) & 0x1f;
        t = (instr >> 21) & 0x1f;
        if (instr & 1)
                vdst = (u8 *)&current->thread.vr_state.vr[t];
        else
                vdst = (u8 *)&current->thread.fp_state.fpr[t][0];

        /* Grab the vector address */
        ea = regs->gpr[rb] + (ra ? regs->gpr[ra] : 0);
        if (is_32bit_task())
                ea &= 0xfffffffful;
        addr = (__force const void __user *)ea;

        /* Check it */
        if (!access_ok(addr, 16)) {
                pr_devel("HMI vec emu: bad access %i:%s[%d] nip=%016lx"
                         " instr=%08x addr=%016lx\n",
                         smp_processor_id(), current->comm, current->pid,
                         regs->nip, instr, (unsigned long)addr);
                return;
        }

        /* Read the vector */
        rc = 0;
        if ((unsigned long)addr & 0xfUL)
                /* unaligned case */
                rc = __copy_from_user_inatomic(vbuf, addr, 16);
        else
                __get_user_atomic_128_aligned(vbuf, addr, rc);
        if (rc) {
                pr_devel("HMI vec emu: page fault %i:%s[%d] nip=%016lx"
                         " instr=%08x addr=%016lx\n",
                         smp_processor_id(), current->comm, current->pid,
                         regs->nip, instr, (unsigned long)addr);
                return;
        }

        pr_devel("HMI vec emu: emulated vector CI %i:%s[%d] nip=%016lx"
                 " instr=%08x addr=%016lx\n",
                 smp_processor_id(), current->comm, current->pid, regs->nip,
                 instr, (unsigned long) addr);

        /* Grab instruction "selector" */
        sel = (instr >> 6) & 3;

        /*
         * Check to make sure the facility is actually enabled. This
         * could happen if we get a false positive hit.
         *
         * lxvd2x/lxvw4x always check MSR VSX sel = 0,2
         * lxvh8x/lxvb16x check MSR VSX or VEC depending on VSR used sel = 1,3
         */
        msr_mask = MSR_VSX;
        if ((sel & 1) && (instr & 1)) /* lxvh8x & lxvb16x + VSR >= 32 */
                msr_mask = MSR_VEC;
        if (!(msr & msr_mask)) {
                pr_devel("HMI vec emu: MSR fac clear %i:%s[%d] nip=%016lx"
                         " instr=%08x msr:%016lx\n",
                         smp_processor_id(), current->comm, current->pid,
                         regs->nip, instr, msr);
                return;
        }

        /* Do logging here before we modify sel based on endian */
        switch (sel) {
        case 0: /* lxvw4x */
                PPC_WARN_EMULATED(lxvw4x, regs);
                break;
        case 1: /* lxvh8x */
                PPC_WARN_EMULATED(lxvh8x, regs);
                break;
        case 2: /* lxvd2x */
                PPC_WARN_EMULATED(lxvd2x, regs);
                break;
        case 3: /* lxvb16x */
                PPC_WARN_EMULATED(lxvb16x, regs);
                break;
        }

#ifdef __LITTLE_ENDIAN__
        /*
         * An LE kernel stores the vector in the task struct as an LE
         * byte array (effectively swapping both the components and
         * the content of the components). Those instructions expect
         * the components to remain in ascending address order, so we
         * swap them back.
         *
         * If we are running a BE user space, the expectation is that
         * of a simple memcpy, so forcing the emulation to look like
         * a lxvb16x should do the trick.
         */
        if (swap)
                sel = 3;

        switch (sel) {
        case 0: /* lxvw4x */
                for (i = 0; i < 4; i++)
                        ((u32 *)vdst)[i] = ((u32 *)vbuf)[3-i];
                break;
        case 1: /* lxvh8x */
                for (i = 0; i < 8; i++)
                        ((u16 *)vdst)[i] = ((u16 *)vbuf)[7-i];
                break;
        case 2: /* lxvd2x */

                for (i = 0; i < 2; i++)
                        ((u64 *)vdst)[i] = ((u64 *)vbuf)[1-i];
                break;
        case 3: /* lxvb16x */
                for (i = 0; i < 16; i++)
                        vdst[i] = vbuf[15-i];
                break;
        }
#else /* __LITTLE_ENDIAN__ */
        /* On a big endian kernel, a BE userspace only needs a memcpy */
        if (!swap)
                sel = 3;

        /* Otherwise, we need to swap the content of the components */
        switch (sel) {
        case 0: /* lxvw4x */
                for (i = 0; i < 4; i++)
                        ((u32 *)vdst)[i] = cpu_to_le32(((u32 *)vbuf)[i]);
                break;
        case 1: /* lxvh8x */
                for (i = 0; i < 8; i++)
                        ((u16 *)vdst)[i] = cpu_to_le16(((u16 *)vbuf)[i]);
                break;
        case 2: /* lxvd2x */
                for (i = 0; i < 2; i++)
                        ((u64 *)vdst)[i] = cpu_to_le64(((u64 *)vbuf)[i]);
                break;
        case 3: /* lxvb16x */
                memcpy(vdst, vbuf, 16);
                break;
        }
#endif /* !__LITTLE_ENDIAN__ */

        /* Go to next instruction */
        regs_add_return_ip(regs, 4);
}
#endif /* CONFIG_VSX */

DEFINE_INTERRUPT_HANDLER_ASYNC(handle_hmi_exception)
{
        struct pt_regs *old_regs;

        old_regs = set_irq_regs(regs);

#ifdef CONFIG_VSX
        /* Real mode flagged P9 special emu is needed */
        if (local_paca->hmi_p9_special_emu) {
                local_paca->hmi_p9_special_emu = 0;

                /*
                 * We don't want to take page faults while doing the
                 * emulation, we just replay the instruction if necessary.
                 */
                pagefault_disable();
                p9_hmi_special_emu(regs);
                pagefault_enable();
        }
#endif /* CONFIG_VSX */

        if (ppc_md.handle_hmi_exception)
                ppc_md.handle_hmi_exception(regs);

        set_irq_regs(old_regs);
}

DEFINE_INTERRUPT_HANDLER(unknown_exception)
{
        printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
               regs->nip, regs->msr, regs->trap);

        _exception(SIGTRAP, regs, TRAP_UNK, 0);
}

DEFINE_INTERRUPT_HANDLER_ASYNC(unknown_async_exception)
{
        printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
               regs->nip, regs->msr, regs->trap);

        _exception(SIGTRAP, regs, TRAP_UNK, 0);
}

DEFINE_INTERRUPT_HANDLER_NMI(unknown_nmi_exception)
{
        printk("Bad trap at PC: %lx, SR: %lx, vector=%lx\n",
               regs->nip, regs->msr, regs->trap);

        _exception(SIGTRAP, regs, TRAP_UNK, 0);

        return 0;
}

DEFINE_INTERRUPT_HANDLER(instruction_breakpoint_exception)
{
        if (notify_die(DIE_IABR_MATCH, "iabr_match", regs, 5,
                                        5, SIGTRAP) == NOTIFY_STOP)
                return;
        if (debugger_iabr_match(regs))
                return;
        _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
}

DEFINE_INTERRUPT_HANDLER(RunModeException)
{
        _exception(SIGTRAP, regs, TRAP_UNK, 0);
}

static void __single_step_exception(struct pt_regs *regs)
{
        clear_single_step(regs);
        clear_br_trace(regs);

        if (kprobe_post_handler(regs))
                return;

        if (notify_die(DIE_SSTEP, "single_step", regs, 5,
                                        5, SIGTRAP) == NOTIFY_STOP)
                return;
        if (debugger_sstep(regs))
                return;

        _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
}

DEFINE_INTERRUPT_HANDLER(single_step_exception)
{
        __single_step_exception(regs);
}

/*
 * After we have successfully emulated an instruction, we have to
 * check if the instruction was being single-stepped, and if so,
 * pretend we got a single-step exception.  This was pointed out
 * by Kumar Gala.  -- paulus
 */
static void emulate_single_step(struct pt_regs *regs)
{
        if (single_stepping(regs))
                __single_step_exception(regs);
}

static inline int __parse_fpscr(unsigned long fpscr)
{
        int ret = FPE_FLTUNK;

        /* Invalid operation */
        if ((fpscr & FPSCR_VE) && (fpscr & FPSCR_VX))
                ret = FPE_FLTINV;

        /* Overflow */
        else if ((fpscr & FPSCR_OE) && (fpscr & FPSCR_OX))
                ret = FPE_FLTOVF;

        /* Underflow */
        else if ((fpscr & FPSCR_UE) && (fpscr & FPSCR_UX))
                ret = FPE_FLTUND;

        /* Divide by zero */
        else if ((fpscr & FPSCR_ZE) && (fpscr & FPSCR_ZX))
                ret = FPE_FLTDIV;

        /* Inexact result */
        else if ((fpscr & FPSCR_XE) && (fpscr & FPSCR_XX))
                ret = FPE_FLTRES;

        return ret;
}

static void parse_fpe(struct pt_regs *regs)
{
        int code = 0;

        flush_fp_to_thread(current);

#ifdef CONFIG_PPC_FPU_REGS
        code = __parse_fpscr(current->thread.fp_state.fpscr);
#endif

        _exception(SIGFPE, regs, code, regs->nip);
}

/*
 * Illegal instruction emulation support.  Originally written to
 * provide the PVR to user applications using the mfspr rd, PVR.
 * Return non-zero if we can't emulate, or -EFAULT if the associated
 * memory access caused an access fault.  Return zero on success.
 *
 * There are a couple of ways to do this, either "decode" the instruction
 * or directly match lots of bits.  In this case, matching lots of
 * bits is faster and easier.
 *
 */
static int emulate_string_inst(struct pt_regs *regs, u32 instword)
{
        u8 rT = (instword >> 21) & 0x1f;
        u8 rA = (instword >> 16) & 0x1f;
        u8 NB_RB = (instword >> 11) & 0x1f;
        u32 num_bytes;
        unsigned long EA;
        int pos = 0;

        /* Early out if we are an invalid form of lswx */
        if ((instword & PPC_INST_STRING_MASK) == PPC_INST_LSWX)
                if ((rT == rA) || (rT == NB_RB))
                        return -EINVAL;

        EA = (rA == 0) ? 0 : regs->gpr[rA];

        switch (instword & PPC_INST_STRING_MASK) {
                case PPC_INST_LSWX:
                case PPC_INST_STSWX:
                        EA += NB_RB;
                        num_bytes = regs->xer & 0x7f;
                        break;
                case PPC_INST_LSWI:
                case PPC_INST_STSWI:
                        num_bytes = (NB_RB == 0) ? 32 : NB_RB;
                        break;
                default:
                        return -EINVAL;
        }

        while (num_bytes != 0)
        {
                u8 val;
                u32 shift = 8 * (3 - (pos & 0x3));

                /* if process is 32-bit, clear upper 32 bits of EA */
                if ((regs->msr & MSR_64BIT) == 0)
                        EA &= 0xFFFFFFFF;

                switch ((instword & PPC_INST_STRING_MASK)) {
                        case PPC_INST_LSWX:
                        case PPC_INST_LSWI:
                                if (get_user(val, (u8 __user *)EA))
                                        return -EFAULT;
                                /* first time updating this reg,
                                 * zero it out */
                                if (pos == 0)
                                        regs->gpr[rT] = 0;
                                regs->gpr[rT] |= val << shift;
                                break;
                        case PPC_INST_STSWI:
                        case PPC_INST_STSWX:
                                val = regs->gpr[rT] >> shift;
                                if (put_user(val, (u8 __user *)EA))
                                        return -EFAULT;
                                break;
                }
                /* move EA to next address */
                EA += 1;
                num_bytes--;

                /* manage our position within the register */
                if (++pos == 4) {
                        pos = 0;
                        if (++rT == 32)
                                rT = 0;
                }
        }

        return 0;
}

static int emulate_popcntb_inst(struct pt_regs *regs, u32 instword)
{
        u32 ra,rs;
        unsigned long tmp;

        ra = (instword >> 16) & 0x1f;
        rs = (instword >> 21) & 0x1f;

        tmp = regs->gpr[rs];
        tmp = tmp - ((tmp >> 1) & 0x5555555555555555ULL);
        tmp = (tmp & 0x3333333333333333ULL) + ((tmp >> 2) & 0x3333333333333333ULL);
        tmp = (tmp + (tmp >> 4)) & 0x0f0f0f0f0f0f0f0fULL;
        regs->gpr[ra] = tmp;

        return 0;
}

static int emulate_isel(struct pt_regs *regs, u32 instword)
{
        u8 rT = (instword >> 21) & 0x1f;
        u8 rA = (instword >> 16) & 0x1f;
        u8 rB = (instword >> 11) & 0x1f;
        u8 BC = (instword >> 6) & 0x1f;
        u8 bit;
        unsigned long tmp;

        tmp = (rA == 0) ? 0 : regs->gpr[rA];
        bit = (regs->ccr >> (31 - BC)) & 0x1;

        regs->gpr[rT] = bit ? tmp : regs->gpr[rB];

        return 0;
}

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
static inline bool tm_abort_check(struct pt_regs *regs, int cause)
{
        /* If we're emulating a load/store in an active transaction, we cannot
         * emulate it as the kernel operates in transaction suspended context.
         * We need to abort the transaction.  This creates a persistent TM
         * abort so tell the user what caused it with a new code.
         */
        if (MSR_TM_TRANSACTIONAL(regs->msr)) {
                tm_enable();
                tm_abort(cause);
                return true;
        }
        return false;
}
#else
static inline bool tm_abort_check(struct pt_regs *regs, int reason)
{
        return false;
}
#endif

static int emulate_instruction(struct pt_regs *regs)
{
        u32 instword;
        u32 rd;

        if (!user_mode(regs))
                return -EINVAL;

        if (get_user(instword, (u32 __user *)(regs->nip)))
                return -EFAULT;

        /* Emulate the mfspr rD, PVR. */
        if ((instword & PPC_INST_MFSPR_PVR_MASK) == PPC_INST_MFSPR_PVR) {
                PPC_WARN_EMULATED(mfpvr, regs);
                rd = (instword >> 21) & 0x1f;
                regs->gpr[rd] = mfspr(SPRN_PVR);
                return 0;
        }

        /* Emulating the dcba insn is just a no-op.  */
        if ((instword & PPC_INST_DCBA_MASK) == PPC_INST_DCBA) {
                PPC_WARN_EMULATED(dcba, regs);
                return 0;
        }

        /* Emulate the mcrxr insn.  */
        if ((instword & PPC_INST_MCRXR_MASK) == PPC_INST_MCRXR) {
                int shift = (instword >> 21) & 0x1c;
                unsigned long msk = 0xf0000000UL >> shift;

                PPC_WARN_EMULATED(mcrxr, regs);
                regs->ccr = (regs->ccr & ~msk) | ((regs->xer >> shift) & msk);
                regs->xer &= ~0xf0000000UL;
                return 0;
        }

        /* Emulate load/store string insn. */
        if ((instword & PPC_INST_STRING_GEN_MASK) == PPC_INST_STRING) {
                if (tm_abort_check(regs,
                                   TM_CAUSE_EMULATE | TM_CAUSE_PERSISTENT))
                        return -EINVAL;
                PPC_WARN_EMULATED(string, regs);
                return emulate_string_inst(regs, instword);
        }

        /* Emulate the popcntb (Population Count Bytes) instruction. */
        if ((instword & PPC_INST_POPCNTB_MASK) == PPC_INST_POPCNTB) {
                PPC_WARN_EMULATED(popcntb, regs);
                return emulate_popcntb_inst(regs, instword);
        }

        /* Emulate isel (Integer Select) instruction */
        if ((instword & PPC_INST_ISEL_MASK) == PPC_INST_ISEL) {
                PPC_WARN_EMULATED(isel, regs);
                return emulate_isel(regs, instword);
        }

        /* Emulate sync instruction variants */
        if ((instword & PPC_INST_SYNC_MASK) == PPC_INST_SYNC) {
                PPC_WARN_EMULATED(sync, regs);
                asm volatile("sync");
                return 0;
        }

#ifdef CONFIG_PPC64
        /* Emulate the mfspr rD, DSCR. */
        if ((((instword & PPC_INST_MFSPR_DSCR_USER_MASK) ==
                PPC_INST_MFSPR_DSCR_USER) ||
             ((instword & PPC_INST_MFSPR_DSCR_MASK) ==
                PPC_INST_MFSPR_DSCR)) &&
                        cpu_has_feature(CPU_FTR_DSCR)) {
                PPC_WARN_EMULATED(mfdscr, regs);
                rd = (instword >> 21) & 0x1f;
                regs->gpr[rd] = mfspr(SPRN_DSCR);
                return 0;
        }
        /* Emulate the mtspr DSCR, rD. */
        if ((((instword & PPC_INST_MTSPR_DSCR_USER_MASK) ==
                PPC_INST_MTSPR_DSCR_USER) ||
             ((instword & PPC_INST_MTSPR_DSCR_MASK) ==
                PPC_INST_MTSPR_DSCR)) &&
                        cpu_has_feature(CPU_FTR_DSCR)) {
                PPC_WARN_EMULATED(mtdscr, regs);
                rd = (instword >> 21) & 0x1f;
                current->thread.dscr = regs->gpr[rd];
                current->thread.dscr_inherit = 1;
                mtspr(SPRN_DSCR, current->thread.dscr);
                return 0;
        }
#endif

        return -EINVAL;
}

int is_valid_bugaddr(unsigned long addr)
{
        return is_kernel_addr(addr);
}

#ifdef CONFIG_MATH_EMULATION
static int emulate_math(struct pt_regs *regs)
{
        int ret;

        ret = do_mathemu(regs);
        if (ret >= 0)
                PPC_WARN_EMULATED(math, regs);

        switch (ret) {
        case 0:
                emulate_single_step(regs);
                return 0;
        case 1: {
                        int code = 0;
                        code = __parse_fpscr(current->thread.fp_state.fpscr);
                        _exception(SIGFPE, regs, code, regs->nip);
                        return 0;
                }
        case -EFAULT:
                _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
                return 0;
        }

        return -1;
}
#else
static inline int emulate_math(struct pt_regs *regs) { return -1; }
#endif

static void do_program_check(struct pt_regs *regs)
{
        unsigned int reason = get_reason(regs);

        /* We can now get here via a FP Unavailable exception if the core
         * has no FPU, in that case the reason flags will be 0 */

        if (reason & REASON_FP) {
                /* IEEE FP exception */
                parse_fpe(regs);
                return;
        }
        if (reason & REASON_TRAP) {
                unsigned long bugaddr;
                /* Debugger is first in line to stop recursive faults in
                 * rcu_lock, notify_die, or atomic_notifier_call_chain */
                if (debugger_bpt(regs))
                        return;

                if (kprobe_handler(regs))
                        return;

                /* trap exception */
                if (notify_die(DIE_BPT, "breakpoint", regs, 5, 5, SIGTRAP)
                                == NOTIFY_STOP)
                        return;

                bugaddr = regs->nip;
                /*
                 * Fixup bugaddr for BUG_ON() in real mode
                 */
                if (!is_kernel_addr(bugaddr) && !(regs->msr & MSR_IR))
                        bugaddr += PAGE_OFFSET;

                if (!(regs->msr & MSR_PR) &&  /* not user-mode */
                    report_bug(bugaddr, regs) == BUG_TRAP_TYPE_WARN) {
                        regs_add_return_ip(regs, 4);
                        return;
                }
                _exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
                return;
        }
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        if (reason & REASON_TM) {
                /* This is a TM "Bad Thing Exception" program check.
                 * This occurs when:
                 * -  An rfid/hrfid/mtmsrd attempts to cause an illegal
                 *    transition in TM states.
                 * -  A trechkpt is attempted when transactional.
                 * -  A treclaim is attempted when non transactional.
                 * -  A tend is illegally attempted.
                 * -  writing a TM SPR when transactional.
                 *
                 * If usermode caused this, it's done something illegal and
                 * gets a SIGILL slap on the wrist.  We call it an illegal
                 * operand to distinguish from the instruction just being bad
                 * (e.g. executing a 'tend' on a CPU without TM!); it's an
                 * illegal /placement/ of a valid instruction.
                 */
                if (user_mode(regs)) {
                        _exception(SIGILL, regs, ILL_ILLOPN, regs->nip);
                        return;
                } else {
                        printk(KERN_EMERG "Unexpected TM Bad Thing exception "
                               "at %lx (msr 0x%lx) tm_scratch=%llx\n",
                               regs->nip, regs->msr, get_paca()->tm_scratch);
                        die("Unrecoverable exception", regs, SIGABRT);
                }
        }
#endif

        /*
         * If we took the program check in the kernel skip down to sending a
         * SIGILL. The subsequent cases all relate to emulating instructions
         * which we should only do for userspace. We also do not want to enable
         * interrupts for kernel faults because that might lead to further
         * faults, and loose the context of the original exception.
         */
        if (!user_mode(regs))
                goto sigill;

        interrupt_cond_local_irq_enable(regs);

        /* (reason & REASON_ILLEGAL) would be the obvious thing here,
         * but there seems to be a hardware bug on the 405GP (RevD)
         * that means ESR is sometimes set incorrectly - either to
         * ESR_DST (!?) or 0.  In the process of chasing this with the
         * hardware people - not sure if it can happen on any illegal
         * instruction or only on FP instructions, whether there is a
         * pattern to occurrences etc. -dgibson 31/Mar/2003
         */
        if (!emulate_math(regs))
                return;

        /* Try to emulate it if we should. */
        if (reason & (REASON_ILLEGAL | REASON_PRIVILEGED)) {
                switch (emulate_instruction(regs)) {
                case 0:
                        regs_add_return_ip(regs, 4);
                        emulate_single_step(regs);
                        return;
                case -EFAULT:
                        _exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);
                        return;
                }
        }

sigill:
        if (reason & REASON_PRIVILEGED)
                _exception(SIGILL, regs, ILL_PRVOPC, regs->nip);
        else
                _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);

}

DEFINE_INTERRUPT_HANDLER(program_check_exception)
{
        do_program_check(regs);
}

/*
 * This occurs when running in hypervisor mode on POWER6 or later
 * and an illegal instruction is encountered.
 */
DEFINE_INTERRUPT_HANDLER(emulation_assist_interrupt)
{
        regs_set_return_msr(regs, regs->msr | REASON_ILLEGAL);
        do_program_check(regs);
}

DEFINE_INTERRUPT_HANDLER(alignment_exception)
{
        int sig, code, fixed = 0;
        unsigned long  reason;

        interrupt_cond_local_irq_enable(regs);

        reason = get_reason(regs);
        if (reason & REASON_BOUNDARY) {
                sig = SIGBUS;
                code = BUS_ADRALN;
                goto bad;
        }

        if (tm_abort_check(regs, TM_CAUSE_ALIGNMENT | TM_CAUSE_PERSISTENT))
                return;

        /* we don't implement logging of alignment exceptions */
        if (!(current->thread.align_ctl & PR_UNALIGN_SIGBUS))
                fixed = fix_alignment(regs);

        if (fixed == 1) {
                /* skip over emulated instruction */
                regs_add_return_ip(regs, inst_length(reason));
                emulate_single_step(regs);
                return;
        }

        /* Operand address was bad */
        if (fixed == -EFAULT) {
                sig = SIGSEGV;
                code = SEGV_ACCERR;
        } else {
                sig = SIGBUS;
                code = BUS_ADRALN;
        }
bad:
        if (user_mode(regs))
                _exception(sig, regs, code, regs->dar);
        else
                bad_page_fault(regs, sig);
}

DEFINE_INTERRUPT_HANDLER(stack_overflow_exception)
{
        die("Kernel stack overflow", regs, SIGSEGV);
}

DEFINE_INTERRUPT_HANDLER(kernel_fp_unavailable_exception)
{
        printk(KERN_EMERG "Unrecoverable FP Unavailable Exception "
                          "%lx at %lx\n", regs->trap, regs->nip);
        die("Unrecoverable FP Unavailable Exception", regs, SIGABRT);
}

DEFINE_INTERRUPT_HANDLER(altivec_unavailable_exception)
{
        if (user_mode(regs)) {
                /* A user program has executed an altivec instruction,
                   but this kernel doesn't support altivec. */
                _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
                return;
        }

        printk(KERN_EMERG "Unrecoverable VMX/Altivec Unavailable Exception "
                        "%lx at %lx\n", regs->trap, regs->nip);
        die("Unrecoverable VMX/Altivec Unavailable Exception", regs, SIGABRT);
}

DEFINE_INTERRUPT_HANDLER(vsx_unavailable_exception)
{
        if (user_mode(regs)) {
                /* A user program has executed an vsx instruction,
                   but this kernel doesn't support vsx. */
                _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
                return;
        }

        printk(KERN_EMERG "Unrecoverable VSX Unavailable Exception "
                        "%lx at %lx\n", regs->trap, regs->nip);
        die("Unrecoverable VSX Unavailable Exception", regs, SIGABRT);
}

#ifdef CONFIG_PPC64
static void tm_unavailable(struct pt_regs *regs)
{
#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
        if (user_mode(regs)) {
                current->thread.load_tm++;
                regs_set_return_msr(regs, regs->msr | MSR_TM);
                tm_enable();
                tm_restore_sprs(&current->thread);
                return;
        }
#endif
        pr_emerg("Unrecoverable TM Unavailable Exception "
                        "%lx at %lx\n", regs->trap, regs->nip);
        die("Unrecoverable TM Unavailable Exception", regs, SIGABRT);
}

DEFINE_INTERRUPT_HANDLER(facility_unavailable_exception)
{
        static char *facility_strings[] = {
                [FSCR_FP_LG] = "FPU",
                [FSCR_VECVSX_LG] = "VMX/VSX",
                [FSCR_DSCR_LG] = "DSCR",
                [FSCR_PM_LG] = "PMU SPRs",
                [FSCR_BHRB_LG] = "BHRB",
                [FSCR_TM_LG] = "TM",
                [FSCR_EBB_LG] = "EBB",
                [FSCR_TAR_LG] = "TAR",
                [FSCR_MSGP_LG] = "MSGP",
                [FSCR_SCV_LG] = "SCV",
                [FSCR_PREFIX_LG] = "PREFIX",
        };
        char *facility = "unknown";
        u64 value;
        u32 instword, rd;
        u8 status;
        bool hv;

        hv = (TRAP(regs) == INTERRUPT_H_FAC_UNAVAIL);
        if (hv)
                value = mfspr(SPRN_HFSCR);
        else
                value = mfspr(SPRN_FSCR);

        status = value >> 56;
        if ((hv || status >= 2) &&
            (status < ARRAY_SIZE(facility_strings)) &&
            facility_strings[status])
                facility = facility_strings[status];

        /* We should not have taken this interrupt in kernel */
        if (!user_mode(regs)) {
                pr_emerg("Facility '%s' unavailable (%d) exception in kernel mode at %lx\n",
                         facility, status, regs->nip);
                die("Unexpected facility unavailable exception", regs, SIGABRT);
        }

        interrupt_cond_local_irq_enable(regs);

        if (status == FSCR_DSCR_LG) {
                /*
                 * User is accessing the DSCR register using the problem
                 * state only SPR number (0x03) either through a mfspr or
                 * a mtspr instruction. If it is a write attempt through
                 * a mtspr, then we set the inherit bit. This also allows
                 * the user to write or read the register directly in the
                 * future by setting via the FSCR DSCR bit. But in case it
                 * is a read DSCR attempt through a mfspr instruction, we
                 * just emulate the instruction instead. This code path will
                 * always emulate all the mfspr instructions till the user
                 * has attempted at least one mtspr instruction. This way it
                 * preserves the same behaviour when the user is accessing
                 * the DSCR through privilege level only SPR number (0x11)
                 * which is emulated through illegal instruction exception.
                 * We always leave HFSCR DSCR set.
                 */
                if (get_user(instword, (u32 __user *)(regs->nip))) {
                        pr_err("Failed to fetch the user instruction\n");
                        return;
                }

                /* Write into DSCR (mtspr 0x03, RS) */
                if ((instword & PPC_INST_MTSPR_DSCR_USER_MASK)
                                == PPC_INST_MTSPR_DSCR_USER) {
                        rd = (instword >> 21) & 0x1f;
                        current->thread.dscr = regs->gpr[rd];
                        current->thread.dscr_inherit = 1;
                        current->thread.fscr |= FSCR_DSCR;
                        mtspr(SPRN_FSCR, current->thread.fscr);
                }

                /* Read from DSCR (mfspr RT, 0x03) */
                if ((instword & PPC_INST_MFSPR_DSCR_USER_MASK)
                                == PPC_INST_MFSPR_DSCR_USER) {
                        if (emulate_instruction(regs)) {
                                pr_err("DSCR based mfspr emulation failed\n");
                                return;
                        }
                        regs_add_return_ip(regs, 4);
                        emulate_single_step(regs);
                }
                return;
        }

        if (status == FSCR_TM_LG) {
                /*
                 * If we're here then the hardware is TM aware because it
                 * generated an exception with FSRM_TM set.
                 *
                 * If cpu_has_feature(CPU_FTR_TM) is false, then either firmware
                 * told us not to do TM, or the kernel is not built with TM
                 * support.
                 *
                 * If both of those things are true, then userspace can spam the
                 * console by triggering the printk() below just by continually
                 * doing tbegin (or any TM instruction). So in that case just
                 * send the process a SIGILL immediately.
                 */
                if (!cpu_has_feature(CPU_FTR_TM))
                        goto out;

                tm_unavailable(regs);
                return;
        }

        pr_err_ratelimited("%sFacility '%s' unavailable (%d), exception at 0x%lx, MSR=%lx\n",
                hv ? "Hypervisor " : "", facility, status, regs->nip, regs->msr);

out:
        _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
}
#endif

#ifdef CONFIG_PPC_TRANSACTIONAL_MEM

DEFINE_INTERRUPT_HANDLER(fp_unavailable_tm)
{
        /* Note:  This does not handle any kind of FP laziness. */

        TM_DEBUG("FP Unavailable trap whilst transactional at 0x%lx, MSR=%lx\n",
                 regs->nip, regs->msr);

        /* We can only have got here if the task started using FP after
         * beginning the transaction.  So, the transactional regs are just a
         * copy of the checkpointed ones.  But, we still need to recheckpoint
         * as we're enabling FP for the process; it will return, abort the
         * transaction, and probably retry but now with FP enabled.  So the
         * checkpointed FP registers need to be loaded.
         */
        tm_reclaim_current(TM_CAUSE_FAC_UNAV);

        /*
         * Reclaim initially saved out bogus (lazy) FPRs to ckfp_state, and
         * then it was overwrite by the thr->fp_state by tm_reclaim_thread().
         *
         * At this point, ck{fp,vr}_state contains the exact values we want to
         * recheckpoint.
         */

        /* Enable FP for the task: */
        current->thread.load_fp = 1;

        /*
         * Recheckpoint all the checkpointed ckpt, ck{fp, vr}_state registers.
         */
        tm_recheckpoint(&current->thread);
}

DEFINE_INTERRUPT_HANDLER(altivec_unavailable_tm)
{
        /* See the comments in fp_unavailable_tm().  This function operates
         * the same way.
         */

        TM_DEBUG("Vector Unavailable trap whilst transactional at 0x%lx,"
                 "MSR=%lx\n",
                 regs->nip, regs->msr);
        tm_reclaim_current(TM_CAUSE_FAC_UNAV);
        current->thread.load_vec = 1;
        tm_recheckpoint(&current->thread);
        current->thread.used_vr = 1;
}

DEFINE_INTERRUPT_HANDLER(vsx_unavailable_tm)
{
        /* See the comments in fp_unavailable_tm().  This works similarly,
         * though we're loading both FP and VEC registers in here.
         *
         * If FP isn't in use, load FP regs.  If VEC isn't in use, load VEC
         * regs.  Either way, set MSR_VSX.
         */

        TM_DEBUG("VSX Unavailable trap whilst transactional at 0x%lx,"
                 "MSR=%lx\n",
                 regs->nip, regs->msr);

        current->thread.used_vsr = 1;

        /* This reclaims FP and/or VR regs if they're already enabled */
        tm_reclaim_current(TM_CAUSE_FAC_UNAV);

        current->thread.load_vec = 1;
        current->thread.load_fp = 1;

        tm_recheckpoint(&current->thread);
}
#endif /* CONFIG_PPC_TRANSACTIONAL_MEM */

#ifdef CONFIG_PPC64
DECLARE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi);
DEFINE_INTERRUPT_HANDLER_NMI(performance_monitor_exception_nmi)
{
        __this_cpu_inc(irq_stat.pmu_irqs);

        perf_irq(regs);

        return 0;
}
#endif

DECLARE_INTERRUPT_HANDLER_ASYNC(performance_monitor_exception_async);
DEFINE_INTERRUPT_HANDLER_ASYNC(performance_monitor_exception_async)
{
        __this_cpu_inc(irq_stat.pmu_irqs);

        perf_irq(regs);
}

DEFINE_INTERRUPT_HANDLER_RAW(performance_monitor_exception)
{
        /*
         * On 64-bit, if perf interrupts hit in a local_irq_disable
         * (soft-masked) region, we consider them as NMIs. This is required to
         * prevent hash faults on user addresses when reading callchains (and
         * looks better from an irq tracing perspective).
         */
        if (IS_ENABLED(CONFIG_PPC64) && unlikely(arch_irq_disabled_regs(regs)))
                performance_monitor_exception_nmi(regs);
        else
                performance_monitor_exception_async(regs);

        return 0;
}

#ifdef CONFIG_PPC_ADV_DEBUG_REGS
static void handle_debug(struct pt_regs *regs, unsigned long debug_status)
{
        int changed = 0;
        /*
         * Determine the cause of the debug event, clear the
         * event flags and send a trap to the handler. Torez
         */
        if (debug_status & (DBSR_DAC1R | DBSR_DAC1W)) {
                dbcr_dac(current) &= ~(DBCR_DAC1R | DBCR_DAC1W);
#ifdef CONFIG_PPC_ADV_DEBUG_DAC_RANGE
                current->thread.debug.dbcr2 &= ~DBCR2_DAC12MODE;
#endif
                do_send_trap(regs, mfspr(SPRN_DAC1), debug_status,
                             5);
                changed |= 0x01;
        }  else if (debug_status & (DBSR_DAC2R | DBSR_DAC2W)) {
                dbcr_dac(current) &= ~(DBCR_DAC2R | DBCR_DAC2W);
                do_send_trap(regs, mfspr(SPRN_DAC2), debug_status,
                             6);
                changed |= 0x01;
        }  else if (debug_status & DBSR_IAC1) {
                current->thread.debug.dbcr0 &= ~DBCR0_IAC1;
                dbcr_iac_range(current) &= ~DBCR_IAC12MODE;
                do_send_trap(regs, mfspr(SPRN_IAC1), debug_status,
                             1);
                changed |= 0x01;
        }  else if (debug_status & DBSR_IAC2) {
                current->thread.debug.dbcr0 &= ~DBCR0_IAC2;
                do_send_trap(regs, mfspr(SPRN_IAC2), debug_status,
                             2);
                changed |= 0x01;
        }  else if (debug_status & DBSR_IAC3) {
                current->thread.debug.dbcr0 &= ~DBCR0_IAC3;
                dbcr_iac_range(current) &= ~DBCR_IAC34MODE;
                do_send_trap(regs, mfspr(SPRN_IAC3), debug_status,
                             3);
                changed |= 0x01;
        }  else if (debug_status & DBSR_IAC4) {
                current->thread.debug.dbcr0 &= ~DBCR0_IAC4;
                do_send_trap(regs, mfspr(SPRN_IAC4), debug_status,
                             4);
                changed |= 0x01;
        }
        /*
         * At the point this routine was called, the MSR(DE) was turned off.
         * Check all other debug flags and see if that bit needs to be turned
         * back on or not.
         */
        if (DBCR_ACTIVE_EVENTS(current->thread.debug.dbcr0,
                               current->thread.debug.dbcr1))
                regs_set_return_msr(regs, regs->msr | MSR_DE);
        else
                /* Make sure the IDM flag is off */
                current->thread.debug.dbcr0 &= ~DBCR0_IDM;

        if (changed & 0x01)
                mtspr(SPRN_DBCR0, current->thread.debug.dbcr0);
}

DEFINE_INTERRUPT_HANDLER(DebugException)
{
        unsigned long debug_status = regs->dsisr;

        current->thread.debug.dbsr = debug_status;

        /* Hack alert: On BookE, Branch Taken stops on the branch itself, while
         * on server, it stops on the target of the branch. In order to simulate
         * the server behaviour, we thus restart right away with a single step
         * instead of stopping here when hitting a BT
         */
        if (debug_status & DBSR_BT) {
                regs_set_return_msr(regs, regs->msr & ~MSR_DE);

                /* Disable BT */
                mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_BT);
                /* Clear the BT event */
                mtspr(SPRN_DBSR, DBSR_BT);

                /* Do the single step trick only when coming from userspace */
                if (user_mode(regs)) {
                        current->thread.debug.dbcr0 &= ~DBCR0_BT;
                        current->thread.debug.dbcr0 |= DBCR0_IDM | DBCR0_IC;
                        regs_set_return_msr(regs, regs->msr | MSR_DE);
                        return;
                }

                if (kprobe_post_handler(regs))
                        return;

                if (notify_die(DIE_SSTEP, "block_step", regs, 5,
                               5, SIGTRAP) == NOTIFY_STOP) {
                        return;
                }
                if (debugger_sstep(regs))

                        return;
        } else if (debug_status & DBSR_IC) {    /* Instruction complete */
                regs_set_return_msr(regs, regs->msr & ~MSR_DE);

                /* Disable instruction completion */
                mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_IC);
                /* Clear the instruction completion event */
                mtspr(SPRN_DBSR, DBSR_IC);

                if (kprobe_post_handler(regs))
                        return;

                if (notify_die(DIE_SSTEP, "single_step", regs, 5,
                               5, SIGTRAP) == NOTIFY_STOP) {
                        return;
                }

                if (debugger_sstep(regs))
                        return;

                if (user_mode(regs)) {
                        current->thread.debug.dbcr0 &= ~DBCR0_IC;
                        if (DBCR_ACTIVE_EVENTS(current->thread.debug.dbcr0,
                                               current->thread.debug.dbcr1))
                                regs_set_return_msr(regs, regs->msr | MSR_DE);
                        else
                                /* Make sure the IDM bit is off */
                                current->thread.debug.dbcr0 &= ~DBCR0_IDM;
                }

                _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
        } else
                handle_debug(regs, debug_status);
}
#endif /* CONFIG_PPC_ADV_DEBUG_REGS */

#ifdef CONFIG_ALTIVEC
DEFINE_INTERRUPT_HANDLER(altivec_assist_exception)
{
        int err;

        if (!user_mode(regs)) {
                printk(KERN_EMERG "VMX/Altivec assist exception in kernel mode"
                       " at %lx\n", regs->nip);
                die("Kernel VMX/Altivec assist exception", regs, SIGILL);
        }

        flush_altivec_to_thread(current);

        PPC_WARN_EMULATED(altivec, regs);
        err = emulate_altivec(regs);
        if (err == 0) {
                regs_add_return_ip(regs, 4); /* skip emulated instruction */
                emulate_single_step(regs);
                return;
        }

        if (err == -EFAULT) {
                /* got an error reading the instruction */
                _exception(SIGSEGV, regs, SEGV_ACCERR, regs->nip);
        } else {
                /* didn't recognize the instruction */
                /* XXX quick hack for now: set the non-Java bit in the VSCR */
                printk_ratelimited(KERN_ERR "Unrecognized altivec instruction "
                                   "in %s at %lx\n", current->comm, regs->nip);
                current->thread.vr_state.vscr.u[3] |= 0x10000;
        }
}
#endif /* CONFIG_ALTIVEC */

#ifdef CONFIG_FSL_BOOKE
DEFINE_INTERRUPT_HANDLER(CacheLockingException)
{
        unsigned long error_code = regs->dsisr;

        /* We treat cache locking instructions from the user
         * as priv ops, in the future we could try to do
         * something smarter
         */
        if (error_code & (ESR_DLK|ESR_ILK))
                _exception(SIGILL, regs, ILL_PRVOPC, regs->nip);
        return;
}
#endif /* CONFIG_FSL_BOOKE */

#ifdef CONFIG_SPE
DEFINE_INTERRUPT_HANDLER(SPEFloatingPointException)
{
        extern int do_spe_mathemu(struct pt_regs *regs);
        unsigned long spefscr;
        int fpexc_mode;
        int code = FPE_FLTUNK;
        int err;

        interrupt_cond_local_irq_enable(regs);

        flush_spe_to_thread(current);

        spefscr = current->thread.spefscr;
        fpexc_mode = current->thread.fpexc_mode;

        if ((spefscr & SPEFSCR_FOVF) && (fpexc_mode & PR_FP_EXC_OVF)) {
                code = FPE_FLTOVF;
        }
        else if ((spefscr & SPEFSCR_FUNF) && (fpexc_mode & PR_FP_EXC_UND)) {
                code = FPE_FLTUND;
        }
        else if ((spefscr & SPEFSCR_FDBZ) && (fpexc_mode & PR_FP_EXC_DIV))
                code = FPE_FLTDIV;
        else if ((spefscr & SPEFSCR_FINV) && (fpexc_mode & PR_FP_EXC_INV)) {
                code = FPE_FLTINV;
        }
        else if ((spefscr & (SPEFSCR_FG | SPEFSCR_FX)) && (fpexc_mode & PR_FP_EXC_RES))
                code = FPE_FLTRES;

        err = do_spe_mathemu(regs);
        if (err == 0) {
                regs_add_return_ip(regs, 4); /* skip emulated instruction */
                emulate_single_step(regs);
                return;
        }

        if (err == -EFAULT) {
                /* got an error reading the instruction */
                _exception(SIGSEGV, regs, SEGV_ACCERR, regs->nip);
        } else if (err == -EINVAL) {
                /* didn't recognize the instruction */
                printk(KERN_ERR "unrecognized spe instruction "
                       "in %s at %lx\n", current->comm, regs->nip);
        } else {
                _exception(SIGFPE, regs, code, regs->nip);
        }

        return;
}

DEFINE_INTERRUPT_HANDLER(SPEFloatingPointRoundException)
{
        extern int speround_handler(struct pt_regs *regs);
        int err;

        interrupt_cond_local_irq_enable(regs);

        preempt_disable();
        if (regs->msr & MSR_SPE)
                giveup_spe(current);
        preempt_enable();

        regs_add_return_ip(regs, -4);
        err = speround_handler(regs);
        if (err == 0) {
                regs_add_return_ip(regs, 4); /* skip emulated instruction */
                emulate_single_step(regs);
                return;
        }

        if (err == -EFAULT) {
                /* got an error reading the instruction */
                _exception(SIGSEGV, regs, SEGV_ACCERR, regs->nip);
        } else if (err == -EINVAL) {
                /* didn't recognize the instruction */
                printk(KERN_ERR "unrecognized spe instruction "
                       "in %s at %lx\n", current->comm, regs->nip);
        } else {
                _exception(SIGFPE, regs, FPE_FLTUNK, regs->nip);
                return;
        }
}
#endif

/*
 * We enter here if we get an unrecoverable exception, that is, one
 * that happened at a point where the RI (recoverable interrupt) bit
 * in the MSR is 0.  This indicates that SRR0/1 are live, and that
 * we therefore lost state by taking this exception.
 */
void __noreturn unrecoverable_exception(struct pt_regs *regs)
{
        pr_emerg("Unrecoverable exception %lx at %lx (msr=%lx)\n",
                 regs->trap, regs->nip, regs->msr);
        die("Unrecoverable exception", regs, SIGABRT);
        /* die() should not return */
        for (;;)
                ;
}

#if defined(CONFIG_BOOKE_WDT) || defined(CONFIG_40x)
/*
 * Default handler for a Watchdog exception,
 * spins until a reboot occurs
 */
void __attribute__ ((weak)) WatchdogHandler(struct pt_regs *regs)
{
        /* Generic WatchdogHandler, implement your own */
        mtspr(SPRN_TCR, mfspr(SPRN_TCR)&(~TCR_WIE));
        return;
}

DEFINE_INTERRUPT_HANDLER_NMI(WatchdogException)
{
        printk (KERN_EMERG "PowerPC Book-E Watchdog Exception\n");
        WatchdogHandler(regs);
        return 0;
}
#endif

/*
 * We enter here if we discover during exception entry that we are
 * running in supervisor mode with a userspace value in the stack pointer.
 */
DEFINE_INTERRUPT_HANDLER(kernel_bad_stack)
{
        printk(KERN_EMERG "Bad kernel stack pointer %lx at %lx\n",
               regs->gpr[1], regs->nip);
        die("Bad kernel stack pointer", regs, SIGABRT);
}

void __init trap_init(void)
{
}


#ifdef CONFIG_PPC_EMULATED_STATS

#define WARN_EMULATED_SETUP(type)       .type = { .name = #type }

struct ppc_emulated ppc_emulated = {
#ifdef CONFIG_ALTIVEC
        WARN_EMULATED_SETUP(altivec),
#endif
        WARN_EMULATED_SETUP(dcba),
        WARN_EMULATED_SETUP(dcbz),
        WARN_EMULATED_SETUP(fp_pair),
        WARN_EMULATED_SETUP(isel),
        WARN_EMULATED_SETUP(mcrxr),
        WARN_EMULATED_SETUP(mfpvr),
        WARN_EMULATED_SETUP(multiple),
        WARN_EMULATED_SETUP(popcntb),
        WARN_EMULATED_SETUP(spe),
        WARN_EMULATED_SETUP(string),
        WARN_EMULATED_SETUP(sync),
        WARN_EMULATED_SETUP(unaligned),
#ifdef CONFIG_MATH_EMULATION
        WARN_EMULATED_SETUP(math),
#endif
#ifdef CONFIG_VSX
        WARN_EMULATED_SETUP(vsx),
#endif
#ifdef CONFIG_PPC64
        WARN_EMULATED_SETUP(mfdscr),
        WARN_EMULATED_SETUP(mtdscr),
        WARN_EMULATED_SETUP(lq_stq),
        WARN_EMULATED_SETUP(lxvw4x),
        WARN_EMULATED_SETUP(lxvh8x),
        WARN_EMULATED_SETUP(lxvd2x),
        WARN_EMULATED_SETUP(lxvb16x),
#endif
};

u32 ppc_warn_emulated;

void ppc_warn_emulated_print(const char *type)
{
        pr_warn_ratelimited("%s used emulated %s instruction\n", current->comm,
                            type);
}

static int __init ppc_warn_emulated_init(void)
{
        struct dentry *dir;
        unsigned int i;
        struct ppc_emulated_entry *entries = (void *)&ppc_emulated;

        dir = debugfs_create_dir("emulated_instructions",
                                 powerpc_debugfs_root);

        debugfs_create_u32("do_warn", 0644, dir, &ppc_warn_emulated);

        for (i = 0; i < sizeof(ppc_emulated)/sizeof(*entries); i++)
                debugfs_create_u32(entries[i].name, 0644, dir,
                                   (u32 *)&entries[i].val.counter);

        return 0;
}

device_initcall(ppc_warn_emulated_init);

#endif /* CONFIG_PPC_EMULATED_STATS */