MIPS: MT: Remove SMTC support

[mirror_ubuntu-zesty-kernel.git] / arch / mips / kernel / traps.c

/*
 * 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.
 *
 * Copyright (C) 1994 - 1999, 2000, 01, 06 Ralf Baechle
 * Copyright (C) 1995, 1996 Paul M. Antoine
 * Copyright (C) 1998 Ulf Carlsson
 * Copyright (C) 1999 Silicon Graphics, Inc.
 * Kevin D. Kissell, kevink@mips.com and Carsten Langgaard, carstenl@mips.com
 * Copyright (C) 2002, 2003, 2004, 2005, 2007  Maciej W. Rozycki
 * Copyright (C) 2000, 2001, 2012 MIPS Technologies, Inc.  All rights reserved.
 * Copyright (C) 2014, Imagination Technologies Ltd.
 */
#include <linux/bug.h>
#include <linux/compiler.h>
#include <linux/context_tracking.h>
#include <linux/kexec.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/bootmem.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/kgdb.h>
#include <linux/kdebug.h>
#include <linux/kprobes.h>
#include <linux/notifier.h>
#include <linux/kdb.h>
#include <linux/irq.h>
#include <linux/perf_event.h>

#include <asm/bootinfo.h>
#include <asm/branch.h>
#include <asm/break.h>
#include <asm/cop2.h>
#include <asm/cpu.h>
#include <asm/cpu-type.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/fpu_emulator.h>
#include <asm/idle.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/module.h>
#include <asm/msa.h>
#include <asm/pgtable.h>
#include <asm/ptrace.h>
#include <asm/sections.h>
#include <asm/tlbdebug.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/watch.h>
#include <asm/mmu_context.h>
#include <asm/types.h>
#include <asm/stacktrace.h>
#include <asm/uasm.h>

extern void check_wait(void);
extern asmlinkage void rollback_handle_int(void);
extern asmlinkage void handle_int(void);
extern u32 handle_tlbl[];
extern u32 handle_tlbs[];
extern u32 handle_tlbm[];
extern asmlinkage void handle_adel(void);
extern asmlinkage void handle_ades(void);
extern asmlinkage void handle_ibe(void);
extern asmlinkage void handle_dbe(void);
extern asmlinkage void handle_sys(void);
extern asmlinkage void handle_bp(void);
extern asmlinkage void handle_ri(void);
extern asmlinkage void handle_ri_rdhwr_vivt(void);
extern asmlinkage void handle_ri_rdhwr(void);
extern asmlinkage void handle_cpu(void);
extern asmlinkage void handle_ov(void);
extern asmlinkage void handle_tr(void);
extern asmlinkage void handle_msa_fpe(void);
extern asmlinkage void handle_fpe(void);
extern asmlinkage void handle_ftlb(void);
extern asmlinkage void handle_msa(void);
extern asmlinkage void handle_mdmx(void);
extern asmlinkage void handle_watch(void);
extern asmlinkage void handle_mt(void);
extern asmlinkage void handle_dsp(void);
extern asmlinkage void handle_mcheck(void);
extern asmlinkage void handle_reserved(void);

void (*board_be_init)(void);
int (*board_be_handler)(struct pt_regs *regs, int is_fixup);
void (*board_nmi_handler_setup)(void);
void (*board_ejtag_handler_setup)(void);
void (*board_bind_eic_interrupt)(int irq, int regset);
void (*board_ebase_setup)(void);
void(*board_cache_error_setup)(void);

static void show_raw_backtrace(unsigned long reg29)
{
        unsigned long *sp = (unsigned long *)(reg29 & ~3);
        unsigned long addr;

        printk("Call Trace:");
#ifdef CONFIG_KALLSYMS
        printk("\n");
#endif
        while (!kstack_end(sp)) {
                unsigned long __user *p =
                        (unsigned long __user *)(unsigned long)sp++;
                if (__get_user(addr, p)) {
                        printk(" (Bad stack address)");
                        break;
                }
                if (__kernel_text_address(addr))
                        print_ip_sym(addr);
        }
        printk("\n");
}

#ifdef CONFIG_KALLSYMS
int raw_show_trace;
static int __init set_raw_show_trace(char *str)
{
        raw_show_trace = 1;
        return 1;
}
__setup("raw_show_trace", set_raw_show_trace);
#endif

static void show_backtrace(struct task_struct *task, const struct pt_regs *regs)
{
        unsigned long sp = regs->regs[29];
        unsigned long ra = regs->regs[31];
        unsigned long pc = regs->cp0_epc;

        if (!task)
                task = current;

        if (raw_show_trace || !__kernel_text_address(pc)) {
                show_raw_backtrace(sp);
                return;
        }
        printk("Call Trace:\n");
        do {
                print_ip_sym(pc);
                pc = unwind_stack(task, &sp, pc, &ra);
        } while (pc);
        printk("\n");
}

/*
 * This routine abuses get_user()/put_user() to reference pointers
 * with at least a bit of error checking ...
 */
static void show_stacktrace(struct task_struct *task,
        const struct pt_regs *regs)
{
        const int field = 2 * sizeof(unsigned long);
        long stackdata;
        int i;
        unsigned long __user *sp = (unsigned long __user *)regs->regs[29];

        printk("Stack :");
        i = 0;
        while ((unsigned long) sp & (PAGE_SIZE - 1)) {
                if (i && ((i % (64 / field)) == 0))
                        printk("\n       ");
                if (i > 39) {
                        printk(" ...");
                        break;
                }

                if (__get_user(stackdata, sp++)) {
                        printk(" (Bad stack address)");
                        break;
                }

                printk(" %0*lx", field, stackdata);
                i++;
        }
        printk("\n");
        show_backtrace(task, regs);
}

void show_stack(struct task_struct *task, unsigned long *sp)
{
        struct pt_regs regs;
        if (sp) {
                regs.regs[29] = (unsigned long)sp;
                regs.regs[31] = 0;
                regs.cp0_epc = 0;
        } else {
                if (task && task != current) {
                        regs.regs[29] = task->thread.reg29;
                        regs.regs[31] = 0;
                        regs.cp0_epc = task->thread.reg31;
#ifdef CONFIG_KGDB_KDB
                } else if (atomic_read(&kgdb_active) != -1 &&
                           kdb_current_regs) {
                        memcpy(&regs, kdb_current_regs, sizeof(regs));
#endif /* CONFIG_KGDB_KDB */
                } else {
                        prepare_frametrace(&regs);
                }
        }
        show_stacktrace(task, &regs);
}

static void show_code(unsigned int __user *pc)
{
        long i;
        unsigned short __user *pc16 = NULL;

        printk("\nCode:");

        if ((unsigned long)pc & 1)
                pc16 = (unsigned short __user *)((unsigned long)pc & ~1);
        for(i = -3 ; i < 6 ; i++) {
                unsigned int insn;
                if (pc16 ? __get_user(insn, pc16 + i) : __get_user(insn, pc + i)) {
                        printk(" (Bad address in epc)\n");
                        break;
                }
                printk("%c%0*x%c", (i?' ':'<'), pc16 ? 4 : 8, insn, (i?' ':'>'));
        }
}

static void __show_regs(const struct pt_regs *regs)
{
        const int field = 2 * sizeof(unsigned long);
        unsigned int cause = regs->cp0_cause;
        int i;

        show_regs_print_info(KERN_DEFAULT);

        /*
         * Saved main processor registers
         */
        for (i = 0; i < 32; ) {
                if ((i % 4) == 0)
                        printk("$%2d   :", i);
                if (i == 0)
                        printk(" %0*lx", field, 0UL);
                else if (i == 26 || i == 27)
                        printk(" %*s", field, "");
                else
                        printk(" %0*lx", field, regs->regs[i]);

                i++;
                if ((i % 4) == 0)
                        printk("\n");
        }

#ifdef CONFIG_CPU_HAS_SMARTMIPS
        printk("Acx    : %0*lx\n", field, regs->acx);
#endif
        printk("Hi    : %0*lx\n", field, regs->hi);
        printk("Lo    : %0*lx\n", field, regs->lo);

        /*
         * Saved cp0 registers
         */
        printk("epc   : %0*lx %pS\n", field, regs->cp0_epc,
               (void *) regs->cp0_epc);
        printk("    %s\n", print_tainted());
        printk("ra    : %0*lx %pS\n", field, regs->regs[31],
               (void *) regs->regs[31]);

        printk("Status: %08x    ", (uint32_t) regs->cp0_status);

        if (cpu_has_3kex) {
                if (regs->cp0_status & ST0_KUO)
                        printk("KUo ");
                if (regs->cp0_status & ST0_IEO)
                        printk("IEo ");
                if (regs->cp0_status & ST0_KUP)
                        printk("KUp ");
                if (regs->cp0_status & ST0_IEP)
                        printk("IEp ");
                if (regs->cp0_status & ST0_KUC)
                        printk("KUc ");
                if (regs->cp0_status & ST0_IEC)
                        printk("IEc ");
        } else if (cpu_has_4kex) {
                if (regs->cp0_status & ST0_KX)
                        printk("KX ");
                if (regs->cp0_status & ST0_SX)
                        printk("SX ");
                if (regs->cp0_status & ST0_UX)
                        printk("UX ");
                switch (regs->cp0_status & ST0_KSU) {
                case KSU_USER:
                        printk("USER ");
                        break;
                case KSU_SUPERVISOR:
                        printk("SUPERVISOR ");
                        break;
                case KSU_KERNEL:
                        printk("KERNEL ");
                        break;
                default:
                        printk("BAD_MODE ");
                        break;
                }
                if (regs->cp0_status & ST0_ERL)
                        printk("ERL ");
                if (regs->cp0_status & ST0_EXL)
                        printk("EXL ");
                if (regs->cp0_status & ST0_IE)
                        printk("IE ");
        }
        printk("\n");

        printk("Cause : %08x\n", cause);

        cause = (cause & CAUSEF_EXCCODE) >> CAUSEB_EXCCODE;
        if (1 <= cause && cause <= 5)
                printk("BadVA : %0*lx\n", field, regs->cp0_badvaddr);

        printk("PrId  : %08x (%s)\n", read_c0_prid(),
               cpu_name_string());
}

/*
 * FIXME: really the generic show_regs should take a const pointer argument.
 */
void show_regs(struct pt_regs *regs)
{
        __show_regs((struct pt_regs *)regs);
}

void show_registers(struct pt_regs *regs)
{
        const int field = 2 * sizeof(unsigned long);
        mm_segment_t old_fs = get_fs();

        __show_regs(regs);
        print_modules();
        printk("Process %s (pid: %d, threadinfo=%p, task=%p, tls=%0*lx)\n",
               current->comm, current->pid, current_thread_info(), current,
              field, current_thread_info()->tp_value);
        if (cpu_has_userlocal) {
                unsigned long tls;

                tls = read_c0_userlocal();
                if (tls != current_thread_info()->tp_value)
                        printk("*HwTLS: %0*lx\n", field, tls);
        }

        if (!user_mode(regs))
                /* Necessary for getting the correct stack content */
                set_fs(KERNEL_DS);
        show_stacktrace(current, regs);
        show_code((unsigned int __user *) regs->cp0_epc);
        printk("\n");
        set_fs(old_fs);
}

static int regs_to_trapnr(struct pt_regs *regs)
{
        return (regs->cp0_cause >> 2) & 0x1f;
}

static DEFINE_RAW_SPINLOCK(die_lock);

void __noreturn die(const char *str, struct pt_regs *regs)
{
        static int die_counter;
        int sig = SIGSEGV;

        oops_enter();

        if (notify_die(DIE_OOPS, str, regs, 0, regs_to_trapnr(regs),
                       SIGSEGV) == NOTIFY_STOP)
                sig = 0;

        console_verbose();
        raw_spin_lock_irq(&die_lock);
        bust_spinlocks(1);

        printk("%s[#%d]:\n", str, ++die_counter);
        show_registers(regs);
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
        raw_spin_unlock_irq(&die_lock);

        oops_exit();

        if (in_interrupt())
                panic("Fatal exception in interrupt");

        if (panic_on_oops) {
                printk(KERN_EMERG "Fatal exception: panic in 5 seconds");
                ssleep(5);
                panic("Fatal exception");
        }

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

        do_exit(sig);
}

extern struct exception_table_entry __start___dbe_table[];
extern struct exception_table_entry __stop___dbe_table[];

__asm__(
"       .section        __dbe_table, \"a\"\n"
"       .previous                       \n");

/* Given an address, look for it in the exception tables. */
static const struct exception_table_entry *search_dbe_tables(unsigned long addr)
{
        const struct exception_table_entry *e;

        e = search_extable(__start___dbe_table, __stop___dbe_table - 1, addr);
        if (!e)
                e = search_module_dbetables(addr);
        return e;
}

asmlinkage void do_be(struct pt_regs *regs)
{
        const int field = 2 * sizeof(unsigned long);
        const struct exception_table_entry *fixup = NULL;
        int data = regs->cp0_cause & 4;
        int action = MIPS_BE_FATAL;
        enum ctx_state prev_state;

        prev_state = exception_enter();
        /* XXX For now.  Fixme, this searches the wrong table ...  */
        if (data && !user_mode(regs))
                fixup = search_dbe_tables(exception_epc(regs));

        if (fixup)
                action = MIPS_BE_FIXUP;

        if (board_be_handler)
                action = board_be_handler(regs, fixup != NULL);

        switch (action) {
        case MIPS_BE_DISCARD:
                goto out;
        case MIPS_BE_FIXUP:
                if (fixup) {
                        regs->cp0_epc = fixup->nextinsn;
                        goto out;
                }
                break;
        default:
                break;
        }

        /*
         * Assume it would be too dangerous to continue ...
         */
        printk(KERN_ALERT "%s bus error, epc == %0*lx, ra == %0*lx\n",
               data ? "Data" : "Instruction",
               field, regs->cp0_epc, field, regs->regs[31]);
        if (notify_die(DIE_OOPS, "bus error", regs, 0, regs_to_trapnr(regs),
                       SIGBUS) == NOTIFY_STOP)
                goto out;

        die_if_kernel("Oops", regs);
        force_sig(SIGBUS, current);

out:
        exception_exit(prev_state);
}

/*
 * ll/sc, rdhwr, sync emulation
 */

#define OPCODE 0xfc000000
#define BASE   0x03e00000
#define RT     0x001f0000
#define OFFSET 0x0000ffff
#define LL     0xc0000000
#define SC     0xe0000000
#define SPEC0  0x00000000
#define SPEC3  0x7c000000
#define RD     0x0000f800
#define FUNC   0x0000003f
#define SYNC   0x0000000f
#define RDHWR  0x0000003b

/*  microMIPS definitions   */
#define MM_POOL32A_FUNC 0xfc00ffff
#define MM_RDHWR        0x00006b3c
#define MM_RS           0x001f0000
#define MM_RT           0x03e00000

/*
 * The ll_bit is cleared by r*_switch.S
 */

unsigned int ll_bit;
struct task_struct *ll_task;

static inline int simulate_ll(struct pt_regs *regs, unsigned int opcode)
{
        unsigned long value, __user *vaddr;
        long offset;

        /*
         * analyse the ll instruction that just caused a ri exception
         * and put the referenced address to addr.
         */

        /* sign extend offset */
        offset = opcode & OFFSET;
        offset <<= 16;
        offset >>= 16;

        vaddr = (unsigned long __user *)
                ((unsigned long)(regs->regs[(opcode & BASE) >> 21]) + offset);

        if ((unsigned long)vaddr & 3)
                return SIGBUS;
        if (get_user(value, vaddr))
                return SIGSEGV;

        preempt_disable();

        if (ll_task == NULL || ll_task == current) {
                ll_bit = 1;
        } else {
                ll_bit = 0;
        }
        ll_task = current;

        preempt_enable();

        regs->regs[(opcode & RT) >> 16] = value;

        return 0;
}

static inline int simulate_sc(struct pt_regs *regs, unsigned int opcode)
{
        unsigned long __user *vaddr;
        unsigned long reg;
        long offset;

        /*
         * analyse the sc instruction that just caused a ri exception
         * and put the referenced address to addr.
         */

        /* sign extend offset */
        offset = opcode & OFFSET;
        offset <<= 16;
        offset >>= 16;

        vaddr = (unsigned long __user *)
                ((unsigned long)(regs->regs[(opcode & BASE) >> 21]) + offset);
        reg = (opcode & RT) >> 16;

        if ((unsigned long)vaddr & 3)
                return SIGBUS;

        preempt_disable();

        if (ll_bit == 0 || ll_task != current) {
                regs->regs[reg] = 0;
                preempt_enable();
                return 0;
        }

        preempt_enable();

        if (put_user(regs->regs[reg], vaddr))
                return SIGSEGV;

        regs->regs[reg] = 1;

        return 0;
}

/*
 * ll uses the opcode of lwc0 and sc uses the opcode of swc0.  That is both
 * opcodes are supposed to result in coprocessor unusable exceptions if
 * executed on ll/sc-less processors.  That's the theory.  In practice a
 * few processors such as NEC's VR4100 throw reserved instruction exceptions
 * instead, so we're doing the emulation thing in both exception handlers.
 */
static int simulate_llsc(struct pt_regs *regs, unsigned int opcode)
{
        if ((opcode & OPCODE) == LL) {
                perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS,
                                1, regs, 0);
                return simulate_ll(regs, opcode);
        }
        if ((opcode & OPCODE) == SC) {
                perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS,
                                1, regs, 0);
                return simulate_sc(regs, opcode);
        }

        return -1;                      /* Must be something else ... */
}

/*
 * Simulate trapping 'rdhwr' instructions to provide user accessible
 * registers not implemented in hardware.
 */
static int simulate_rdhwr(struct pt_regs *regs, int rd, int rt)
{
        struct thread_info *ti = task_thread_info(current);

        perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS,
                        1, regs, 0);
        switch (rd) {
        case 0:         /* CPU number */
                regs->regs[rt] = smp_processor_id();
                return 0;
        case 1:         /* SYNCI length */
                regs->regs[rt] = min(current_cpu_data.dcache.linesz,
                                     current_cpu_data.icache.linesz);
                return 0;
        case 2:         /* Read count register */
                regs->regs[rt] = read_c0_count();
                return 0;
        case 3:         /* Count register resolution */
                switch (current_cpu_type()) {
                case CPU_20KC:
                case CPU_25KF:
                        regs->regs[rt] = 1;
                        break;
                default:
                        regs->regs[rt] = 2;
                }
                return 0;
        case 29:
                regs->regs[rt] = ti->tp_value;
                return 0;
        default:
                return -1;
        }
}

static int simulate_rdhwr_normal(struct pt_regs *regs, unsigned int opcode)
{
        if ((opcode & OPCODE) == SPEC3 && (opcode & FUNC) == RDHWR) {
                int rd = (opcode & RD) >> 11;
                int rt = (opcode & RT) >> 16;

                simulate_rdhwr(regs, rd, rt);
                return 0;
        }

        /* Not ours.  */
        return -1;
}

static int simulate_rdhwr_mm(struct pt_regs *regs, unsigned short opcode)
{
        if ((opcode & MM_POOL32A_FUNC) == MM_RDHWR) {
                int rd = (opcode & MM_RS) >> 16;
                int rt = (opcode & MM_RT) >> 21;
                simulate_rdhwr(regs, rd, rt);
                return 0;
        }

        /* Not ours.  */
        return -1;
}

static int simulate_sync(struct pt_regs *regs, unsigned int opcode)
{
        if ((opcode & OPCODE) == SPEC0 && (opcode & FUNC) == SYNC) {
                perf_sw_event(PERF_COUNT_SW_EMULATION_FAULTS,
                                1, regs, 0);
                return 0;
        }

        return -1;                      /* Must be something else ... */
}

asmlinkage void do_ov(struct pt_regs *regs)
{
        enum ctx_state prev_state;
        siginfo_t info;

        prev_state = exception_enter();
        die_if_kernel("Integer overflow", regs);

        info.si_code = FPE_INTOVF;
        info.si_signo = SIGFPE;
        info.si_errno = 0;
        info.si_addr = (void __user *) regs->cp0_epc;
        force_sig_info(SIGFPE, &info, current);
        exception_exit(prev_state);
}

int process_fpemu_return(int sig, void __user *fault_addr)
{
        if (sig == SIGSEGV || sig == SIGBUS) {
                struct siginfo si = {0};
                si.si_addr = fault_addr;
                si.si_signo = sig;
                if (sig == SIGSEGV) {
                        if (find_vma(current->mm, (unsigned long)fault_addr))
                                si.si_code = SEGV_ACCERR;
                        else
                                si.si_code = SEGV_MAPERR;
                } else {
                        si.si_code = BUS_ADRERR;
                }
                force_sig_info(sig, &si, current);
                return 1;
        } else if (sig) {
                force_sig(sig, current);
                return 1;
        } else {
                return 0;
        }
}

/*
 * XXX Delayed fp exceptions when doing a lazy ctx switch XXX
 */
asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
{
        enum ctx_state prev_state;
        siginfo_t info = {0};

        prev_state = exception_enter();
        if (notify_die(DIE_FP, "FP exception", regs, 0, regs_to_trapnr(regs),
                       SIGFPE) == NOTIFY_STOP)
                goto out;
        die_if_kernel("FP exception in kernel code", regs);

        if (fcr31 & FPU_CSR_UNI_X) {
                int sig;
                void __user *fault_addr = NULL;

                /*
                 * Unimplemented operation exception.  If we've got the full
                 * software emulator on-board, let's use it...
                 *
                 * Force FPU to dump state into task/thread context.  We're
                 * moving a lot of data here for what is probably a single
                 * instruction, but the alternative is to pre-decode the FP
                 * register operands before invoking the emulator, which seems
                 * a bit extreme for what should be an infrequent event.
                 */
                /* Ensure 'resume' not overwrite saved fp context again. */
                lose_fpu(1);

                /* Run the emulator */
                sig = fpu_emulator_cop1Handler(regs, &current->thread.fpu, 1,
                                               &fault_addr);

                /*
                 * We can't allow the emulated instruction to leave any of
                 * the cause bit set in $fcr31.
                 */
                current->thread.fpu.fcr31 &= ~FPU_CSR_ALL_X;

                /* Restore the hardware register state */
                own_fpu(1);     /* Using the FPU again.  */

                /* If something went wrong, signal */
                process_fpemu_return(sig, fault_addr);

                goto out;
        } else if (fcr31 & FPU_CSR_INV_X)
                info.si_code = FPE_FLTINV;
        else if (fcr31 & FPU_CSR_DIV_X)
                info.si_code = FPE_FLTDIV;
        else if (fcr31 & FPU_CSR_OVF_X)
                info.si_code = FPE_FLTOVF;
        else if (fcr31 & FPU_CSR_UDF_X)
                info.si_code = FPE_FLTUND;
        else if (fcr31 & FPU_CSR_INE_X)
                info.si_code = FPE_FLTRES;
        else
                info.si_code = __SI_FAULT;
        info.si_signo = SIGFPE;
        info.si_errno = 0;
        info.si_addr = (void __user *) regs->cp0_epc;
        force_sig_info(SIGFPE, &info, current);

out:
        exception_exit(prev_state);
}

static void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
        const char *str)
{
        siginfo_t info;
        char b[40];

#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
        if (kgdb_ll_trap(DIE_TRAP, str, regs, code, regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
                return;
#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */

        if (notify_die(DIE_TRAP, str, regs, code, regs_to_trapnr(regs),
                       SIGTRAP) == NOTIFY_STOP)
                return;

        /*
         * A short test says that IRIX 5.3 sends SIGTRAP for all trap
         * insns, even for trap and break codes that indicate arithmetic
         * failures.  Weird ...
         * But should we continue the brokenness???  --macro
         */
        switch (code) {
        case BRK_OVERFLOW:
        case BRK_DIVZERO:
                scnprintf(b, sizeof(b), "%s instruction in kernel code", str);
                die_if_kernel(b, regs);
                if (code == BRK_DIVZERO)
                        info.si_code = FPE_INTDIV;
                else
                        info.si_code = FPE_INTOVF;
                info.si_signo = SIGFPE;
                info.si_errno = 0;
                info.si_addr = (void __user *) regs->cp0_epc;
                force_sig_info(SIGFPE, &info, current);
                break;
        case BRK_BUG:
                die_if_kernel("Kernel bug detected", regs);
                force_sig(SIGTRAP, current);
                break;
        case BRK_MEMU:
                /*
                 * Address errors may be deliberately induced by the FPU
                 * emulator to retake control of the CPU after executing the
                 * instruction in the delay slot of an emulated branch.
                 *
                 * Terminate if exception was recognized as a delay slot return
                 * otherwise handle as normal.
                 */
                if (do_dsemulret(regs))
                        return;

                die_if_kernel("Math emu break/trap", regs);
                force_sig(SIGTRAP, current);
                break;
        default:
                scnprintf(b, sizeof(b), "%s instruction in kernel code", str);
                die_if_kernel(b, regs);
                force_sig(SIGTRAP, current);
        }
}

asmlinkage void do_bp(struct pt_regs *regs)
{
        unsigned int opcode, bcode;
        enum ctx_state prev_state;
        unsigned long epc;
        u16 instr[2];
        mm_segment_t seg;

        seg = get_fs();
        if (!user_mode(regs))
                set_fs(KERNEL_DS);

        prev_state = exception_enter();
        if (get_isa16_mode(regs->cp0_epc)) {
                /* Calculate EPC. */
                epc = exception_epc(regs);
                if (cpu_has_mmips) {
                        if ((__get_user(instr[0], (u16 __user *)msk_isa16_mode(epc)) ||
                            (__get_user(instr[1], (u16 __user *)msk_isa16_mode(epc + 2)))))
                                goto out_sigsegv;
                        opcode = (instr[0] << 16) | instr[1];
                } else {
                        /* MIPS16e mode */
                        if (__get_user(instr[0],
                                       (u16 __user *)msk_isa16_mode(epc)))
                                goto out_sigsegv;
                        bcode = (instr[0] >> 6) & 0x3f;
                        do_trap_or_bp(regs, bcode, "Break");
                        goto out;
                }
        } else {
                if (__get_user(opcode,
                               (unsigned int __user *) exception_epc(regs)))
                        goto out_sigsegv;
        }

        /*
         * There is the ancient bug in the MIPS assemblers that the break
         * code starts left to bit 16 instead to bit 6 in the opcode.
         * Gas is bug-compatible, but not always, grrr...
         * We handle both cases with a simple heuristics.  --macro
         */
        bcode = ((opcode >> 6) & ((1 << 20) - 1));
        if (bcode >= (1 << 10))
                bcode >>= 10;

        /*
         * notify the kprobe handlers, if instruction is likely to
         * pertain to them.
         */
        switch (bcode) {
        case BRK_KPROBE_BP:
                if (notify_die(DIE_BREAK, "debug", regs, bcode,
                               regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
                        goto out;
                else
                        break;
        case BRK_KPROBE_SSTEPBP:
                if (notify_die(DIE_SSTEPBP, "single_step", regs, bcode,
                               regs_to_trapnr(regs), SIGTRAP) == NOTIFY_STOP)
                        goto out;
                else
                        break;
        default:
                break;
        }

        do_trap_or_bp(regs, bcode, "Break");

out:
        set_fs(seg);
        exception_exit(prev_state);
        return;

out_sigsegv:
        force_sig(SIGSEGV, current);
        goto out;
}

asmlinkage void do_tr(struct pt_regs *regs)
{
        u32 opcode, tcode = 0;
        enum ctx_state prev_state;
        u16 instr[2];
        mm_segment_t seg;
        unsigned long epc = msk_isa16_mode(exception_epc(regs));

        seg = get_fs();
        if (!user_mode(regs))
                set_fs(get_ds());

        prev_state = exception_enter();
        if (get_isa16_mode(regs->cp0_epc)) {
                if (__get_user(instr[0], (u16 __user *)(epc + 0)) ||
                    __get_user(instr[1], (u16 __user *)(epc + 2)))
                        goto out_sigsegv;
                opcode = (instr[0] << 16) | instr[1];
                /* Immediate versions don't provide a code.  */
                if (!(opcode & OPCODE))
                        tcode = (opcode >> 12) & ((1 << 4) - 1);
        } else {
                if (__get_user(opcode, (u32 __user *)epc))
                        goto out_sigsegv;
                /* Immediate versions don't provide a code.  */
                if (!(opcode & OPCODE))
                        tcode = (opcode >> 6) & ((1 << 10) - 1);
        }

        do_trap_or_bp(regs, tcode, "Trap");

out:
        set_fs(seg);
        exception_exit(prev_state);
        return;

out_sigsegv:
        force_sig(SIGSEGV, current);
        goto out;
}

asmlinkage void do_ri(struct pt_regs *regs)
{
        unsigned int __user *epc = (unsigned int __user *)exception_epc(regs);
        unsigned long old_epc = regs->cp0_epc;
        unsigned long old31 = regs->regs[31];
        enum ctx_state prev_state;
        unsigned int opcode = 0;
        int status = -1;

        prev_state = exception_enter();
        if (notify_die(DIE_RI, "RI Fault", regs, 0, regs_to_trapnr(regs),
                       SIGILL) == NOTIFY_STOP)
                goto out;

        die_if_kernel("Reserved instruction in kernel code", regs);

        if (unlikely(compute_return_epc(regs) < 0))
                goto out;

        if (get_isa16_mode(regs->cp0_epc)) {
                unsigned short mmop[2] = { 0 };

                if (unlikely(get_user(mmop[0], epc) < 0))
                        status = SIGSEGV;
                if (unlikely(get_user(mmop[1], epc) < 0))
                        status = SIGSEGV;
                opcode = (mmop[0] << 16) | mmop[1];

                if (status < 0)
                        status = simulate_rdhwr_mm(regs, opcode);
        } else {
                if (unlikely(get_user(opcode, epc) < 0))
                        status = SIGSEGV;

                if (!cpu_has_llsc && status < 0)
                        status = simulate_llsc(regs, opcode);

                if (status < 0)
                        status = simulate_rdhwr_normal(regs, opcode);

                if (status < 0)
                        status = simulate_sync(regs, opcode);
        }

        if (status < 0)
                status = SIGILL;

        if (unlikely(status > 0)) {
                regs->cp0_epc = old_epc;                /* Undo skip-over.  */
                regs->regs[31] = old31;
                force_sig(status, current);
        }

out:
        exception_exit(prev_state);
}

/*
 * MIPS MT processors may have fewer FPU contexts than CPU threads. If we've
 * emulated more than some threshold number of instructions, force migration to
 * a "CPU" that has FP support.
 */
static void mt_ase_fp_affinity(void)
{
#ifdef CONFIG_MIPS_MT_FPAFF
        if (mt_fpemul_threshold > 0 &&
             ((current->thread.emulated_fp++ > mt_fpemul_threshold))) {
                /*
                 * If there's no FPU present, or if the application has already
                 * restricted the allowed set to exclude any CPUs with FPUs,
                 * we'll skip the procedure.
                 */
                if (cpus_intersects(current->cpus_allowed, mt_fpu_cpumask)) {
                        cpumask_t tmask;

                        current->thread.user_cpus_allowed
                                = current->cpus_allowed;
                        cpus_and(tmask, current->cpus_allowed,
                                mt_fpu_cpumask);
                        set_cpus_allowed_ptr(current, &tmask);
                        set_thread_flag(TIF_FPUBOUND);
                }
        }
#endif /* CONFIG_MIPS_MT_FPAFF */
}

/*
 * No lock; only written during early bootup by CPU 0.
 */
static RAW_NOTIFIER_HEAD(cu2_chain);

int __ref register_cu2_notifier(struct notifier_block *nb)
{
        return raw_notifier_chain_register(&cu2_chain, nb);
}

int cu2_notifier_call_chain(unsigned long val, void *v)
{
        return raw_notifier_call_chain(&cu2_chain, val, v);
}

static int default_cu2_call(struct notifier_block *nfb, unsigned long action,
        void *data)
{
        struct pt_regs *regs = data;

        die_if_kernel("COP2: Unhandled kernel unaligned access or invalid "
                              "instruction", regs);
        force_sig(SIGILL, current);

        return NOTIFY_OK;
}

static int enable_restore_fp_context(int msa)
{
        int err, was_fpu_owner;

        if (!used_math()) {
                /* First time FP context user. */
                err = init_fpu();
                if (msa && !err)
                        enable_msa();
                if (!err)
                        set_used_math();
                return err;
        }

        /*
         * This task has formerly used the FP context.
         *
         * If this thread has no live MSA vector context then we can simply
         * restore the scalar FP context. If it has live MSA vector context
         * (that is, it has or may have used MSA since last performing a
         * function call) then we'll need to restore the vector context. This
         * applies even if we're currently only executing a scalar FP
         * instruction. This is because if we were to later execute an MSA
         * instruction then we'd either have to:
         *
         *  - Restore the vector context & clobber any registers modified by
         *    scalar FP instructions between now & then.
         *
         * or
         *
         *  - Not restore the vector context & lose the most significant bits
         *    of all vector registers.
         *
         * Neither of those options is acceptable. We cannot restore the least
         * significant bits of the registers now & only restore the most
         * significant bits later because the most significant bits of any
         * vector registers whose aliased FP register is modified now will have
         * been zeroed. We'd have no way to know that when restoring the vector
         * context & thus may load an outdated value for the most significant
         * bits of a vector register.
         */
        if (!msa && !thread_msa_context_live())
                return own_fpu(1);

        /*
         * This task is using or has previously used MSA. Thus we require
         * that Status.FR == 1.
         */
        was_fpu_owner = is_fpu_owner();
        err = own_fpu(0);
        if (err)
                return err;

        enable_msa();
        write_msa_csr(current->thread.fpu.msacsr);
        set_thread_flag(TIF_USEDMSA);

        /*
         * If this is the first time that the task is using MSA and it has
         * previously used scalar FP in this time slice then we already nave
         * FP context which we shouldn't clobber.
         */
        if (!test_and_set_thread_flag(TIF_MSA_CTX_LIVE) && was_fpu_owner)
                return 0;

        /* We need to restore the vector context. */
        restore_msa(current);
        return 0;
}

asmlinkage void do_cpu(struct pt_regs *regs)
{
        enum ctx_state prev_state;
        unsigned int __user *epc;
        unsigned long old_epc, old31;
        unsigned int opcode;
        unsigned int cpid;
        int status, err;
        unsigned long __maybe_unused flags;

        prev_state = exception_enter();
        cpid = (regs->cp0_cause >> CAUSEB_CE) & 3;

        if (cpid != 2)
                die_if_kernel("do_cpu invoked from kernel context!", regs);

        switch (cpid) {
        case 0:
                epc = (unsigned int __user *)exception_epc(regs);
                old_epc = regs->cp0_epc;
                old31 = regs->regs[31];
                opcode = 0;
                status = -1;

                if (unlikely(compute_return_epc(regs) < 0))
                        goto out;

                if (get_isa16_mode(regs->cp0_epc)) {
                        unsigned short mmop[2] = { 0 };

                        if (unlikely(get_user(mmop[0], epc) < 0))
                                status = SIGSEGV;
                        if (unlikely(get_user(mmop[1], epc) < 0))
                                status = SIGSEGV;
                        opcode = (mmop[0] << 16) | mmop[1];

                        if (status < 0)
                                status = simulate_rdhwr_mm(regs, opcode);
                } else {
                        if (unlikely(get_user(opcode, epc) < 0))
                                status = SIGSEGV;

                        if (!cpu_has_llsc && status < 0)
                                status = simulate_llsc(regs, opcode);

                        if (status < 0)
                                status = simulate_rdhwr_normal(regs, opcode);
                }

                if (status < 0)
                        status = SIGILL;

                if (unlikely(status > 0)) {
                        regs->cp0_epc = old_epc;        /* Undo skip-over.  */
                        regs->regs[31] = old31;
                        force_sig(status, current);
                }

                goto out;

        case 3:
                /*
                 * Old (MIPS I and MIPS II) processors will set this code
                 * for COP1X opcode instructions that replaced the original
                 * COP3 space.  We don't limit COP1 space instructions in
                 * the emulator according to the CPU ISA, so we want to
                 * treat COP1X instructions consistently regardless of which
                 * code the CPU chose.  Therefore we redirect this trap to
                 * the FP emulator too.
                 *
                 * Then some newer FPU-less processors use this code
                 * erroneously too, so they are covered by this choice
                 * as well.
                 */
                if (raw_cpu_has_fpu)
                        break;
                /* Fall through.  */

        case 1:
                err = enable_restore_fp_context(0);

                if (!raw_cpu_has_fpu || err) {
                        int sig;
                        void __user *fault_addr = NULL;
                        sig = fpu_emulator_cop1Handler(regs,
                                                       &current->thread.fpu,
                                                       0, &fault_addr);
                        if (!process_fpemu_return(sig, fault_addr) && !err)
                                mt_ase_fp_affinity();
                }

                goto out;

        case 2:
                raw_notifier_call_chain(&cu2_chain, CU2_EXCEPTION, regs);
                goto out;
        }

        force_sig(SIGILL, current);

out:
        exception_exit(prev_state);
}

asmlinkage void do_msa_fpe(struct pt_regs *regs)
{
        enum ctx_state prev_state;

        prev_state = exception_enter();
        die_if_kernel("do_msa_fpe invoked from kernel context!", regs);
        force_sig(SIGFPE, current);
        exception_exit(prev_state);
}

asmlinkage void do_msa(struct pt_regs *regs)
{
        enum ctx_state prev_state;
        int err;

        prev_state = exception_enter();

        if (!cpu_has_msa || test_thread_flag(TIF_32BIT_FPREGS)) {
                force_sig(SIGILL, current);
                goto out;
        }

        die_if_kernel("do_msa invoked from kernel context!", regs);

        err = enable_restore_fp_context(1);
        if (err)
                force_sig(SIGILL, current);
out:
        exception_exit(prev_state);
}

asmlinkage void do_mdmx(struct pt_regs *regs)
{
        enum ctx_state prev_state;

        prev_state = exception_enter();
        force_sig(SIGILL, current);
        exception_exit(prev_state);
}

/*
 * Called with interrupts disabled.
 */
asmlinkage void do_watch(struct pt_regs *regs)
{
        enum ctx_state prev_state;
        u32 cause;

        prev_state = exception_enter();
        /*
         * Clear WP (bit 22) bit of cause register so we don't loop
         * forever.
         */
        cause = read_c0_cause();
        cause &= ~(1 << 22);
        write_c0_cause(cause);

        /*
         * If the current thread has the watch registers loaded, save
         * their values and send SIGTRAP.  Otherwise another thread
         * left the registers set, clear them and continue.
         */
        if (test_tsk_thread_flag(current, TIF_LOAD_WATCH)) {
                mips_read_watch_registers();
                local_irq_enable();
                force_sig(SIGTRAP, current);
        } else {
                mips_clear_watch_registers();
                local_irq_enable();
        }
        exception_exit(prev_state);
}

asmlinkage void do_mcheck(struct pt_regs *regs)
{
        const int field = 2 * sizeof(unsigned long);
        int multi_match = regs->cp0_status & ST0_TS;
        enum ctx_state prev_state;

        prev_state = exception_enter();
        show_regs(regs);

        if (multi_match) {
                printk("Index   : %0x\n", read_c0_index());
                printk("Pagemask: %0x\n", read_c0_pagemask());
                printk("EntryHi : %0*lx\n", field, read_c0_entryhi());
                printk("EntryLo0: %0*lx\n", field, read_c0_entrylo0());
                printk("EntryLo1: %0*lx\n", field, read_c0_entrylo1());
                printk("\n");
                dump_tlb_all();
        }

        show_code((unsigned int __user *) regs->cp0_epc);

        /*
         * Some chips may have other causes of machine check (e.g. SB1
         * graduation timer)
         */
        panic("Caught Machine Check exception - %scaused by multiple "
              "matching entries in the TLB.",
              (multi_match) ? "" : "not ");
}

asmlinkage void do_mt(struct pt_regs *regs)
{
        int subcode;

        subcode = (read_vpe_c0_vpecontrol() & VPECONTROL_EXCPT)
                        >> VPECONTROL_EXCPT_SHIFT;
        switch (subcode) {
        case 0:
                printk(KERN_DEBUG "Thread Underflow\n");
                break;
        case 1:
                printk(KERN_DEBUG "Thread Overflow\n");
                break;
        case 2:
                printk(KERN_DEBUG "Invalid YIELD Qualifier\n");
                break;
        case 3:
                printk(KERN_DEBUG "Gating Storage Exception\n");
                break;
        case 4:
                printk(KERN_DEBUG "YIELD Scheduler Exception\n");
                break;
        case 5:
                printk(KERN_DEBUG "Gating Storage Scheduler Exception\n");
                break;
        default:
                printk(KERN_DEBUG "*** UNKNOWN THREAD EXCEPTION %d ***\n",
                        subcode);
                break;
        }
        die_if_kernel("MIPS MT Thread exception in kernel", regs);

        force_sig(SIGILL, current);
}


asmlinkage void do_dsp(struct pt_regs *regs)
{
        if (cpu_has_dsp)
                panic("Unexpected DSP exception");

        force_sig(SIGILL, current);
}

asmlinkage void do_reserved(struct pt_regs *regs)
{
        /*
         * Game over - no way to handle this if it ever occurs.  Most probably
         * caused by a new unknown cpu type or after another deadly
         * hard/software error.
         */
        show_regs(regs);
        panic("Caught reserved exception %ld - should not happen.",
              (regs->cp0_cause & 0x7f) >> 2);
}

static int __initdata l1parity = 1;
static int __init nol1parity(char *s)
{
        l1parity = 0;
        return 1;
}
__setup("nol1par", nol1parity);
static int __initdata l2parity = 1;
static int __init nol2parity(char *s)
{
        l2parity = 0;
        return 1;
}
__setup("nol2par", nol2parity);

/*
 * Some MIPS CPUs can enable/disable for cache parity detection, but do
 * it different ways.
 */
static inline void parity_protection_init(void)
{
        switch (current_cpu_type()) {
        case CPU_24K:
        case CPU_34K:
        case CPU_74K:
        case CPU_1004K:
        case CPU_1074K:
        case CPU_INTERAPTIV:
        case CPU_PROAPTIV:
        case CPU_P5600:
                {
#define ERRCTL_PE       0x80000000
#define ERRCTL_L2P      0x00800000
                        unsigned long errctl;
                        unsigned int l1parity_present, l2parity_present;

                        errctl = read_c0_ecc();
                        errctl &= ~(ERRCTL_PE|ERRCTL_L2P);

                        /* probe L1 parity support */
                        write_c0_ecc(errctl | ERRCTL_PE);
                        back_to_back_c0_hazard();
                        l1parity_present = (read_c0_ecc() & ERRCTL_PE);

                        /* probe L2 parity support */
                        write_c0_ecc(errctl|ERRCTL_L2P);
                        back_to_back_c0_hazard();
                        l2parity_present = (read_c0_ecc() & ERRCTL_L2P);

                        if (l1parity_present && l2parity_present) {
                                if (l1parity)
                                        errctl |= ERRCTL_PE;
                                if (l1parity ^ l2parity)
                                        errctl |= ERRCTL_L2P;
                        } else if (l1parity_present) {
                                if (l1parity)
                                        errctl |= ERRCTL_PE;
                        } else if (l2parity_present) {
                                if (l2parity)
                                        errctl |= ERRCTL_L2P;
                        } else {
                                /* No parity available */
                        }

                        printk(KERN_INFO "Writing ErrCtl register=%08lx\n", errctl);

                        write_c0_ecc(errctl);
                        back_to_back_c0_hazard();
                        errctl = read_c0_ecc();
                        printk(KERN_INFO "Readback ErrCtl register=%08lx\n", errctl);

                        if (l1parity_present)
                                printk(KERN_INFO "Cache parity protection %sabled\n",
                                       (errctl & ERRCTL_PE) ? "en" : "dis");

                        if (l2parity_present) {
                                if (l1parity_present && l1parity)
                                        errctl ^= ERRCTL_L2P;
                                printk(KERN_INFO "L2 cache parity protection %sabled\n",
                                       (errctl & ERRCTL_L2P) ? "en" : "dis");
                        }
                }
                break;

        case CPU_5KC:
        case CPU_5KE:
        case CPU_LOONGSON1:
                write_c0_ecc(0x80000000);
                back_to_back_c0_hazard();
                /* Set the PE bit (bit 31) in the c0_errctl register. */
                printk(KERN_INFO "Cache parity protection %sabled\n",
                       (read_c0_ecc() & 0x80000000) ? "en" : "dis");
                break;
        case CPU_20KC:
        case CPU_25KF:
                /* Clear the DE bit (bit 16) in the c0_status register. */
                printk(KERN_INFO "Enable cache parity protection for "
                       "MIPS 20KC/25KF CPUs.\n");
                clear_c0_status(ST0_DE);
                break;
        default:
                break;
        }
}

asmlinkage void cache_parity_error(void)
{
        const int field = 2 * sizeof(unsigned long);
        unsigned int reg_val;

        /* For the moment, report the problem and hang. */
        printk("Cache error exception:\n");
        printk("cp0_errorepc == %0*lx\n", field, read_c0_errorepc());
        reg_val = read_c0_cacheerr();
        printk("c0_cacheerr == %08x\n", reg_val);

        printk("Decoded c0_cacheerr: %s cache fault in %s reference.\n",
               reg_val & (1<<30) ? "secondary" : "primary",
               reg_val & (1<<31) ? "data" : "insn");
        if (cpu_has_mips_r2 &&
            ((current_cpu_data.processor_id && 0xff0000) == PRID_COMP_MIPS)) {
                pr_err("Error bits: %s%s%s%s%s%s%s%s\n",
                        reg_val & (1<<29) ? "ED " : "",
                        reg_val & (1<<28) ? "ET " : "",
                        reg_val & (1<<27) ? "ES " : "",
                        reg_val & (1<<26) ? "EE " : "",
                        reg_val & (1<<25) ? "EB " : "",
                        reg_val & (1<<24) ? "EI " : "",
                        reg_val & (1<<23) ? "E1 " : "",
                        reg_val & (1<<22) ? "E0 " : "");
        } else {
                pr_err("Error bits: %s%s%s%s%s%s%s\n",
                        reg_val & (1<<29) ? "ED " : "",
                        reg_val & (1<<28) ? "ET " : "",
                        reg_val & (1<<26) ? "EE " : "",
                        reg_val & (1<<25) ? "EB " : "",
                        reg_val & (1<<24) ? "EI " : "",
                        reg_val & (1<<23) ? "E1 " : "",
                        reg_val & (1<<22) ? "E0 " : "");
        }
        printk("IDX: 0x%08x\n", reg_val & ((1<<22)-1));

#if defined(CONFIG_CPU_MIPS32) || defined(CONFIG_CPU_MIPS64)
        if (reg_val & (1<<22))
                printk("DErrAddr0: 0x%0*lx\n", field, read_c0_derraddr0());

        if (reg_val & (1<<23))
                printk("DErrAddr1: 0x%0*lx\n", field, read_c0_derraddr1());
#endif

        panic("Can't handle the cache error!");
}

asmlinkage void do_ftlb(void)
{
        const int field = 2 * sizeof(unsigned long);
        unsigned int reg_val;

        /* For the moment, report the problem and hang. */
        if (cpu_has_mips_r2 &&
            ((current_cpu_data.processor_id && 0xff0000) == PRID_COMP_MIPS)) {
                pr_err("FTLB error exception, cp0_ecc=0x%08x:\n",
                       read_c0_ecc());
                pr_err("cp0_errorepc == %0*lx\n", field, read_c0_errorepc());
                reg_val = read_c0_cacheerr();
                pr_err("c0_cacheerr == %08x\n", reg_val);

                if ((reg_val & 0xc0000000) == 0xc0000000) {
                        pr_err("Decoded c0_cacheerr: FTLB parity error\n");
                } else {
                        pr_err("Decoded c0_cacheerr: %s cache fault in %s reference.\n",
                               reg_val & (1<<30) ? "secondary" : "primary",
                               reg_val & (1<<31) ? "data" : "insn");
                }
        } else {
                pr_err("FTLB error exception\n");
        }
        /* Just print the cacheerr bits for now */
        cache_parity_error();
}

/*
 * SDBBP EJTAG debug exception handler.
 * We skip the instruction and return to the next instruction.
 */
void ejtag_exception_handler(struct pt_regs *regs)
{
        const int field = 2 * sizeof(unsigned long);
        unsigned long depc, old_epc, old_ra;
        unsigned int debug;

        printk(KERN_DEBUG "SDBBP EJTAG debug exception - not handled yet, just ignored!\n");
        depc = read_c0_depc();
        debug = read_c0_debug();
        printk(KERN_DEBUG "c0_depc = %0*lx, DEBUG = %08x\n", field, depc, debug);
        if (debug & 0x80000000) {
                /*
                 * In branch delay slot.
                 * We cheat a little bit here and use EPC to calculate the
                 * debug return address (DEPC). EPC is restored after the
                 * calculation.
                 */
                old_epc = regs->cp0_epc;
                old_ra = regs->regs[31];
                regs->cp0_epc = depc;
                compute_return_epc(regs);
                depc = regs->cp0_epc;
                regs->cp0_epc = old_epc;
                regs->regs[31] = old_ra;
        } else
                depc += 4;
        write_c0_depc(depc);

#if 0
        printk(KERN_DEBUG "\n\n----- Enable EJTAG single stepping ----\n\n");
        write_c0_debug(debug | 0x100);
#endif
}

/*
 * NMI exception handler.
 * No lock; only written during early bootup by CPU 0.
 */
static RAW_NOTIFIER_HEAD(nmi_chain);

int register_nmi_notifier(struct notifier_block *nb)
{
        return raw_notifier_chain_register(&nmi_chain, nb);
}

void __noreturn nmi_exception_handler(struct pt_regs *regs)
{
        char str[100];

        raw_notifier_call_chain(&nmi_chain, 0, regs);
        bust_spinlocks(1);
        snprintf(str, 100, "CPU%d NMI taken, CP0_EPC=%lx\n",
                 smp_processor_id(), regs->cp0_epc);
        regs->cp0_epc = read_c0_errorepc();
        die(str, regs);
}

#define VECTORSPACING 0x100     /* for EI/VI mode */

unsigned long ebase;
unsigned long exception_handlers[32];
unsigned long vi_handlers[64];

void __init *set_except_vector(int n, void *addr)
{
        unsigned long handler = (unsigned long) addr;
        unsigned long old_handler;

#ifdef CONFIG_CPU_MICROMIPS
        /*
         * Only the TLB handlers are cache aligned with an even
         * address. All other handlers are on an odd address and
         * require no modification. Otherwise, MIPS32 mode will
         * be entered when handling any TLB exceptions. That
         * would be bad...since we must stay in microMIPS mode.
         */
        if (!(handler & 0x1))
                handler |= 1;
#endif
        old_handler = xchg(&exception_handlers[n], handler);

        if (n == 0 && cpu_has_divec) {
#ifdef CONFIG_CPU_MICROMIPS
                unsigned long jump_mask = ~((1 << 27) - 1);
#else
                unsigned long jump_mask = ~((1 << 28) - 1);
#endif
                u32 *buf = (u32 *)(ebase + 0x200);
                unsigned int k0 = 26;
                if ((handler & jump_mask) == ((ebase + 0x200) & jump_mask)) {
                        uasm_i_j(&buf, handler & ~jump_mask);
                        uasm_i_nop(&buf);
                } else {
                        UASM_i_LA(&buf, k0, handler);
                        uasm_i_jr(&buf, k0);
                        uasm_i_nop(&buf);
                }
                local_flush_icache_range(ebase + 0x200, (unsigned long)buf);
        }
        return (void *)old_handler;
}

static void do_default_vi(void)
{
        show_regs(get_irq_regs());
        panic("Caught unexpected vectored interrupt.");
}

static void *set_vi_srs_handler(int n, vi_handler_t addr, int srs)
{
        unsigned long handler;
        unsigned long old_handler = vi_handlers[n];
        int srssets = current_cpu_data.srsets;
        u16 *h;
        unsigned char *b;

        BUG_ON(!cpu_has_veic && !cpu_has_vint);

        if (addr == NULL) {
                handler = (unsigned long) do_default_vi;
                srs = 0;
        } else
                handler = (unsigned long) addr;
        vi_handlers[n] = handler;

        b = (unsigned char *)(ebase + 0x200 + n*VECTORSPACING);

        if (srs >= srssets)
                panic("Shadow register set %d not supported", srs);

        if (cpu_has_veic) {
                if (board_bind_eic_interrupt)
                        board_bind_eic_interrupt(n, srs);
        } else if (cpu_has_vint) {
                /* SRSMap is only defined if shadow sets are implemented */
                if (srssets > 1)
                        change_c0_srsmap(0xf << n*4, srs << n*4);
        }

        if (srs == 0) {
                /*
                 * If no shadow set is selected then use the default handler
                 * that does normal register saving and standard interrupt exit
                 */
                extern char except_vec_vi, except_vec_vi_lui;
                extern char except_vec_vi_ori, except_vec_vi_end;
                extern char rollback_except_vec_vi;
                char *vec_start = using_rollback_handler() ?
                        &rollback_except_vec_vi : &except_vec_vi;
#if defined(CONFIG_CPU_MICROMIPS) || defined(CONFIG_CPU_BIG_ENDIAN)
                const int lui_offset = &except_vec_vi_lui - vec_start + 2;
                const int ori_offset = &except_vec_vi_ori - vec_start + 2;
#else
                const int lui_offset = &except_vec_vi_lui - vec_start;
                const int ori_offset = &except_vec_vi_ori - vec_start;
#endif
                const int handler_len = &except_vec_vi_end - vec_start;

                if (handler_len > VECTORSPACING) {
                        /*
                         * Sigh... panicing won't help as the console
                         * is probably not configured :(
                         */
                        panic("VECTORSPACING too small");
                }

                set_handler(((unsigned long)b - ebase), vec_start,
#ifdef CONFIG_CPU_MICROMIPS
                                (handler_len - 1));
#else
                                handler_len);
#endif
                h = (u16 *)(b + lui_offset);
                *h = (handler >> 16) & 0xffff;
                h = (u16 *)(b + ori_offset);
                *h = (handler & 0xffff);
                local_flush_icache_range((unsigned long)b,
                                         (unsigned long)(b+handler_len));
        }
        else {
                /*
                 * In other cases jump directly to the interrupt handler. It
                 * is the handler's responsibility to save registers if required
                 * (eg hi/lo) and return from the exception using "eret".
                 */
                u32 insn;

                h = (u16 *)b;
                /* j handler */
#ifdef CONFIG_CPU_MICROMIPS
                insn = 0xd4000000 | (((u32)handler & 0x07ffffff) >> 1);
#else
                insn = 0x08000000 | (((u32)handler & 0x0fffffff) >> 2);
#endif
                h[0] = (insn >> 16) & 0xffff;
                h[1] = insn & 0xffff;
                h[2] = 0;
                h[3] = 0;
                local_flush_icache_range((unsigned long)b,
                                         (unsigned long)(b+8));
        }

        return (void *)old_handler;
}

void *set_vi_handler(int n, vi_handler_t addr)
{
        return set_vi_srs_handler(n, addr, 0);
}

extern void tlb_init(void);

/*
 * Timer interrupt
 */
int cp0_compare_irq;
EXPORT_SYMBOL_GPL(cp0_compare_irq);
int cp0_compare_irq_shift;

/*
 * Performance counter IRQ or -1 if shared with timer
 */
int cp0_perfcount_irq;
EXPORT_SYMBOL_GPL(cp0_perfcount_irq);

static int noulri;

static int __init ulri_disable(char *s)
{
        pr_info("Disabling ulri\n");
        noulri = 1;

        return 1;
}
__setup("noulri", ulri_disable);

void per_cpu_trap_init(bool is_boot_cpu)
{
        unsigned int cpu = smp_processor_id();
        unsigned int status_set = ST0_CU0;
        unsigned int hwrena = cpu_hwrena_impl_bits;

        /*
         * Disable coprocessors and select 32-bit or 64-bit addressing
         * and the 16/32 or 32/32 FPR register model.  Reset the BEV
         * flag that some firmware may have left set and the TS bit (for
         * IP27).  Set XX for ISA IV code to work.
         */
#ifdef CONFIG_64BIT
        status_set |= ST0_FR|ST0_KX|ST0_SX|ST0_UX;
#endif
        if (current_cpu_data.isa_level & MIPS_CPU_ISA_IV)
                status_set |= ST0_XX;
        if (cpu_has_dsp)
                status_set |= ST0_MX;

        change_c0_status(ST0_CU|ST0_MX|ST0_RE|ST0_FR|ST0_BEV|ST0_TS|ST0_KX|ST0_SX|ST0_UX,
                         status_set);

        if (cpu_has_mips_r2)
                hwrena |= 0x0000000f;

        if (!noulri && cpu_has_userlocal)
                hwrena |= (1 << 29);

        if (hwrena)
                write_c0_hwrena(hwrena);

        if (cpu_has_veic || cpu_has_vint) {
                unsigned long sr = set_c0_status(ST0_BEV);
                write_c0_ebase(ebase);
                write_c0_status(sr);
                /* Setting vector spacing enables EI/VI mode  */
                change_c0_intctl(0x3e0, VECTORSPACING);
        }
        if (cpu_has_divec) {
                if (cpu_has_mipsmt) {
                        unsigned int vpflags = dvpe();
                        set_c0_cause(CAUSEF_IV);
                        evpe(vpflags);
                } else
                        set_c0_cause(CAUSEF_IV);
        }

        /*
         * Before R2 both interrupt numbers were fixed to 7, so on R2 only:
         *
         *  o read IntCtl.IPTI to determine the timer interrupt
         *  o read IntCtl.IPPCI to determine the performance counter interrupt
         */
        if (cpu_has_mips_r2) {
                cp0_compare_irq_shift = CAUSEB_TI - CAUSEB_IP;
                cp0_compare_irq = (read_c0_intctl() >> INTCTLB_IPTI) & 7;
                cp0_perfcount_irq = (read_c0_intctl() >> INTCTLB_IPPCI) & 7;
                if (cp0_perfcount_irq == cp0_compare_irq)
                        cp0_perfcount_irq = -1;
        } else {
                cp0_compare_irq = CP0_LEGACY_COMPARE_IRQ;
                cp0_compare_irq_shift = CP0_LEGACY_PERFCNT_IRQ;
                cp0_perfcount_irq = -1;
        }

        if (!cpu_data[cpu].asid_cache)
                cpu_data[cpu].asid_cache = ASID_FIRST_VERSION;

        atomic_inc(&init_mm.mm_count);
        current->active_mm = &init_mm;
        BUG_ON(current->mm);
        enter_lazy_tlb(&init_mm, current);

                /* Boot CPU's cache setup in setup_arch(). */
                if (!is_boot_cpu)
                        cpu_cache_init();
                tlb_init();
        TLBMISS_HANDLER_SETUP();
}

/* Install CPU exception handler */
void set_handler(unsigned long offset, void *addr, unsigned long size)
{
#ifdef CONFIG_CPU_MICROMIPS
        memcpy((void *)(ebase + offset), ((unsigned char *)addr - 1), size);
#else
        memcpy((void *)(ebase + offset), addr, size);
#endif
        local_flush_icache_range(ebase + offset, ebase + offset + size);
}

static char panic_null_cerr[] =
        "Trying to set NULL cache error exception handler";

/*
 * Install uncached CPU exception handler.
 * This is suitable only for the cache error exception which is the only
 * exception handler that is being run uncached.
 */
void set_uncached_handler(unsigned long offset, void *addr,
        unsigned long size)
{
        unsigned long uncached_ebase = CKSEG1ADDR(ebase);

        if (!addr)
                panic(panic_null_cerr);

        memcpy((void *)(uncached_ebase + offset), addr, size);
}

static int __initdata rdhwr_noopt;
static int __init set_rdhwr_noopt(char *str)
{
        rdhwr_noopt = 1;
        return 1;
}

__setup("rdhwr_noopt", set_rdhwr_noopt);

void __init trap_init(void)
{
        extern char except_vec3_generic;
        extern char except_vec4;
        extern char except_vec3_r4000;
        unsigned long i;

        check_wait();

#if defined(CONFIG_KGDB)
        if (kgdb_early_setup)
                return; /* Already done */
#endif

        if (cpu_has_veic || cpu_has_vint) {
                unsigned long size = 0x200 + VECTORSPACING*64;
                ebase = (unsigned long)
                        __alloc_bootmem(size, 1 << fls(size), 0);
        } else {
#ifdef CONFIG_KVM_GUEST
#define KVM_GUEST_KSEG0     0x40000000
        ebase = KVM_GUEST_KSEG0;
#else
        ebase = CKSEG0;
#endif
                if (cpu_has_mips_r2)
                        ebase += (read_c0_ebase() & 0x3ffff000);
        }

        if (cpu_has_mmips) {
                unsigned int config3 = read_c0_config3();

                if (IS_ENABLED(CONFIG_CPU_MICROMIPS))
                        write_c0_config3(config3 | MIPS_CONF3_ISA_OE);
                else
                        write_c0_config3(config3 & ~MIPS_CONF3_ISA_OE);
        }

        if (board_ebase_setup)
                board_ebase_setup();
        per_cpu_trap_init(true);

        /*
         * Copy the generic exception handlers to their final destination.
         * This will be overriden later as suitable for a particular
         * configuration.
         */
        set_handler(0x180, &except_vec3_generic, 0x80);

        /*
         * Setup default vectors
         */
        for (i = 0; i <= 31; i++)
                set_except_vector(i, handle_reserved);

        /*
         * Copy the EJTAG debug exception vector handler code to it's final
         * destination.
         */
        if (cpu_has_ejtag && board_ejtag_handler_setup)
                board_ejtag_handler_setup();

        /*
         * Only some CPUs have the watch exceptions.
         */
        if (cpu_has_watch)
                set_except_vector(23, handle_watch);

        /*
         * Initialise interrupt handlers
         */
        if (cpu_has_veic || cpu_has_vint) {
                int nvec = cpu_has_veic ? 64 : 8;
                for (i = 0; i < nvec; i++)
                        set_vi_handler(i, NULL);
        }
        else if (cpu_has_divec)
                set_handler(0x200, &except_vec4, 0x8);

        /*
         * Some CPUs can enable/disable for cache parity detection, but does
         * it different ways.
         */
        parity_protection_init();

        /*
         * The Data Bus Errors / Instruction Bus Errors are signaled
         * by external hardware.  Therefore these two exceptions
         * may have board specific handlers.
         */
        if (board_be_init)
                board_be_init();

        set_except_vector(0, using_rollback_handler() ? rollback_handle_int
                                                      : handle_int);
        set_except_vector(1, handle_tlbm);
        set_except_vector(2, handle_tlbl);
        set_except_vector(3, handle_tlbs);

        set_except_vector(4, handle_adel);
        set_except_vector(5, handle_ades);

        set_except_vector(6, handle_ibe);
        set_except_vector(7, handle_dbe);

        set_except_vector(8, handle_sys);
        set_except_vector(9, handle_bp);
        set_except_vector(10, rdhwr_noopt ? handle_ri :
                          (cpu_has_vtag_icache ?
                           handle_ri_rdhwr_vivt : handle_ri_rdhwr));
        set_except_vector(11, handle_cpu);
        set_except_vector(12, handle_ov);
        set_except_vector(13, handle_tr);
        set_except_vector(14, handle_msa_fpe);

        if (current_cpu_type() == CPU_R6000 ||
            current_cpu_type() == CPU_R6000A) {
                /*
                 * The R6000 is the only R-series CPU that features a machine
                 * check exception (similar to the R4000 cache error) and
                 * unaligned ldc1/sdc1 exception.  The handlers have not been
                 * written yet.  Well, anyway there is no R6000 machine on the
                 * current list of targets for Linux/MIPS.
                 * (Duh, crap, there is someone with a triple R6k machine)
                 */
                //set_except_vector(14, handle_mc);
                //set_except_vector(15, handle_ndc);
        }


        if (board_nmi_handler_setup)
                board_nmi_handler_setup();

        if (cpu_has_fpu && !cpu_has_nofpuex)
                set_except_vector(15, handle_fpe);

        set_except_vector(16, handle_ftlb);
        set_except_vector(21, handle_msa);
        set_except_vector(22, handle_mdmx);

        if (cpu_has_mcheck)
                set_except_vector(24, handle_mcheck);

        if (cpu_has_mipsmt)
                set_except_vector(25, handle_mt);

        set_except_vector(26, handle_dsp);

        if (board_cache_error_setup)
                board_cache_error_setup();

        if (cpu_has_vce)
                /* Special exception: R4[04]00 uses also the divec space. */
                set_handler(0x180, &except_vec3_r4000, 0x100);
        else if (cpu_has_4kex)
                set_handler(0x180, &except_vec3_generic, 0x80);
        else
                set_handler(0x080, &except_vec3_generic, 0x80);

        local_flush_icache_range(ebase, ebase + 0x400);

        sort_extable(__start___dbe_table, __stop___dbe_table);

        cu2_notifier(default_cu2_call, 0x80000000);     /* Run last  */
}