[MIPS] Use conditional traps for BUG_ON on MIPS II and better.

[deliverable/linux.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) 2000, 01 MIPS Technologies, Inc.
 * Copyright (C) 2002, 2003, 2004, 2005  Maciej W. Rozycki
 */
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/bootmem.h>
#include <linux/interrupt.h>

#include <asm/bootinfo.h>
#include <asm/branch.h>
#include <asm/break.h>
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/module.h>
#include <asm/pgtable.h>
#include <asm/ptrace.h>
#include <asm/sections.h>
#include <asm/system.h>
#include <asm/tlbdebug.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
#include <asm/watch.h>
#include <asm/types.h>
#include <asm/stacktrace.h>

extern asmlinkage void handle_int(void);
extern asmlinkage void handle_tlbm(void);
extern asmlinkage void handle_tlbl(void);
extern asmlinkage void handle_tlbs(void);
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_fpe(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);

extern int fpu_emulator_cop1Handler(struct pt_regs *xcp,
        struct mips_fpu_struct *ctx, int has_fpu);

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);


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

        printk("Call Trace:");
#ifdef CONFIG_KALLSYMS
        printk("\n");
#endif
        while (!kstack_end(sp)) {
                addr = *sp++;
                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, struct pt_regs *regs)
{
        unsigned long sp = regs->regs[29];
        unsigned long ra = regs->regs[31];
        unsigned long pc = regs->cp0_epc;

        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, struct pt_regs *regs)
{
        const int field = 2 * sizeof(unsigned long);
        long stackdata;
        int i;
        unsigned long *sp = (unsigned long *)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;
                } else {
                        prepare_frametrace(&regs);
                }
        }
        show_stacktrace(task, &regs);
}

/*
 * The architecture-independent dump_stack generator
 */
void dump_stack(void)
{
        struct pt_regs regs;

        prepare_frametrace(&regs);
        show_backtrace(current, &regs);
}

EXPORT_SYMBOL(dump_stack);

void show_code(unsigned int *pc)
{
        long i;

        printk("\nCode:");

        for(i = -3 ; i < 6 ; i++) {
                unsigned int insn;
                if (__get_user(insn, pc + i)) {
                        printk(" (Bad address in epc)\n");
                        break;
                }
                printk("%c%08x%c", (i?' ':'<'), insn, (i?' ':'>'));
        }
}

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

        printk("Cpu %d\n", smp_processor_id());

        /*
         * 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");
        }

        printk("Hi    : %0*lx\n", field, regs->hi);
        printk("Lo    : %0*lx\n", field, regs->lo);

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

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

        if (current_cpu_data.isa_level == MIPS_CPU_ISA_I) {
                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 (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\n", read_c0_prid());
}

void show_registers(struct pt_regs *regs)
{
        show_regs(regs);
        print_modules();
        printk("Process %s (pid: %d, threadinfo=%p, task=%p)\n",
                current->comm, current->pid, current_thread_info(), current);
        show_stacktrace(current, regs);
        show_code((unsigned int *) regs->cp0_epc);
        printk("\n");
}

static DEFINE_SPINLOCK(die_lock);

NORET_TYPE void ATTRIB_NORET die(const char * str, struct pt_regs * regs)
{
        static int die_counter;
#ifdef CONFIG_MIPS_MT_SMTC
        unsigned long dvpret = dvpe();
#endif /* CONFIG_MIPS_MT_SMTC */

        console_verbose();
        spin_lock_irq(&die_lock);
        bust_spinlocks(1);
#ifdef CONFIG_MIPS_MT_SMTC
        mips_mt_regdump(dvpret);
#endif /* CONFIG_MIPS_MT_SMTC */
        printk("%s[#%d]:\n", str, ++die_counter);
        show_registers(regs);
        spin_unlock_irq(&die_lock);

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

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

        do_exit(SIGSEGV);
}

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

void __declare_dbe_table(void)
{
        __asm__ __volatile__(
        ".section\t__dbe_table,\"a\"\n\t"
        ".previous"
        );
}

/* 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;

        /* 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 != 0);

        switch (action) {
        case MIPS_BE_DISCARD:
                return;
        case MIPS_BE_FIXUP:
                if (fixup) {
                        regs->cp0_epc = fixup->nextinsn;
                        return;
                }
                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]);
        die_if_kernel("Oops", regs);
        force_sig(SIGBUS, current);
}

/*
 * ll/sc emulation
 */

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

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

unsigned long ll_bit;

static struct task_struct *ll_task = NULL;

static inline void simulate_ll(struct pt_regs *regs, unsigned int opcode)
{
        unsigned long value, __user *vaddr;
        long offset;
        int signal = 0;

        /*
         * 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) {
                signal = SIGBUS;
                goto sig;
        }
        if (get_user(value, vaddr)) {
                signal = SIGSEGV;
                goto sig;
        }

        preempt_disable();

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

        preempt_enable();

        compute_return_epc(regs);

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

        return;

sig:
        force_sig(signal, current);
}

static inline void simulate_sc(struct pt_regs *regs, unsigned int opcode)
{
        unsigned long __user *vaddr;
        unsigned long reg;
        long offset;
        int signal = 0;

        /*
         * 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) {
                signal = SIGBUS;
                goto sig;
        }

        preempt_disable();

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

        preempt_enable();

        if (put_user(regs->regs[reg], vaddr)) {
                signal = SIGSEGV;
                goto sig;
        }

        compute_return_epc(regs);
        regs->regs[reg] = 1;

        return;

sig:
        force_sig(signal, current);
}

/*
 * 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 inline int simulate_llsc(struct pt_regs *regs)
{
        unsigned int opcode;

        if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
                goto out_sigsegv;

        if ((opcode & OPCODE) == LL) {
                simulate_ll(regs, opcode);
                return 0;
        }
        if ((opcode & OPCODE) == SC) {
                simulate_sc(regs, opcode);
                return 0;
        }

        return -EFAULT;                 /* Strange things going on ... */

out_sigsegv:
        force_sig(SIGSEGV, current);
        return -EFAULT;
}

/*
 * Simulate trapping 'rdhwr' instructions to provide user accessible
 * registers not implemented in hardware.  The only current use of this
 * is the thread area pointer.
 */
static inline int simulate_rdhwr(struct pt_regs *regs)
{
        struct thread_info *ti = task_thread_info(current);
        unsigned int opcode;

        if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
                goto out_sigsegv;

        if (unlikely(compute_return_epc(regs)))
                return -EFAULT;

        if ((opcode & OPCODE) == SPEC3 && (opcode & FUNC) == RDHWR) {
                int rd = (opcode & RD) >> 11;
                int rt = (opcode & RT) >> 16;
                switch (rd) {
                        case 29:
                                regs->regs[rt] = ti->tp_value;
                                return 0;
                        default:
                                return -EFAULT;
                }
        }

        /* Not ours.  */
        return -EFAULT;

out_sigsegv:
        force_sig(SIGSEGV, current);
        return -EFAULT;
}

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

        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);
}

/*
 * XXX Delayed fp exceptions when doing a lazy ctx switch XXX
 */
asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
{
        die_if_kernel("FP exception in kernel code", regs);

        if (fcr31 & FPU_CSR_UNI_X) {
                int sig;

                preempt_disable();

#ifdef CONFIG_PREEMPT
                if (!is_fpu_owner()) {
                        /* We might lose fpu before disabling preempt... */
                        own_fpu();
                        BUG_ON(!used_math());
                        restore_fp(current);
                }
#endif
                /*
                 * 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.
                 */
                save_fp(current);
                /* Ensure 'resume' not overwrite saved fp context again. */
                lose_fpu();

                preempt_enable();

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

                preempt_disable();

                own_fpu();      /* Using the FPU again.  */
                /*
                 * 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 */
                restore_fp(current);

                preempt_enable();

                /* If something went wrong, signal */
                if (sig)
                        force_sig(sig, current);

                return;
        }

        force_sig(SIGFPE, current);
}

asmlinkage void do_bp(struct pt_regs *regs)
{
        unsigned int opcode, bcode;
        siginfo_t info;

        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;

        /*
         * (A short test says that IRIX 5.3 sends SIGTRAP for all break
         * insns, even for break codes that indicate arithmetic failures.
         * Weird ...)
         * But should we continue the brokenness???  --macro
         */
        switch (bcode) {
        case BRK_OVERFLOW << 10:
        case BRK_DIVZERO << 10:
                die_if_kernel("Break instruction in kernel code", regs);
                if (bcode == (BRK_DIVZERO << 10))
                        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("Kernel bug detected", regs);
                break;
        default:
                die_if_kernel("Break instruction in kernel code", regs);
                force_sig(SIGTRAP, current);
        }

out_sigsegv:
        force_sig(SIGSEGV, current);
}

asmlinkage void do_tr(struct pt_regs *regs)
{
        unsigned int opcode, tcode = 0;
        siginfo_t info;

        if (get_user(opcode, (unsigned int __user *) exception_epc(regs)))
                goto out_sigsegv;

        /* Immediate versions don't provide a code.  */
        if (!(opcode & OPCODE))
                tcode = ((opcode >> 6) & ((1 << 10) - 1));

        /*
         * (A short test says that IRIX 5.3 sends SIGTRAP for all trap
         * insns, even for trap codes that indicate arithmetic failures.
         * Weird ...)
         * But should we continue the brokenness???  --macro
         */
        switch (tcode) {
        case BRK_OVERFLOW:
        case BRK_DIVZERO:
                die_if_kernel("Trap instruction in kernel code", regs);
                if (tcode == 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("Kernel bug detected", regs);
                break;
        default:
                die_if_kernel("Trap instruction in kernel code", regs);
                force_sig(SIGTRAP, current);
        }

out_sigsegv:
        force_sig(SIGSEGV, current);
}

asmlinkage void do_ri(struct pt_regs *regs)
{
        die_if_kernel("Reserved instruction in kernel code", regs);

        if (!cpu_has_llsc)
                if (!simulate_llsc(regs))
                        return;

        if (!simulate_rdhwr(regs))
                return;

        force_sig(SIGILL, current);
}

asmlinkage void do_cpu(struct pt_regs *regs)
{
        unsigned int cpid;

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

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

        switch (cpid) {
        case 0:
                if (!cpu_has_llsc)
                        if (!simulate_llsc(regs))
                                return;

                if (!simulate_rdhwr(regs))
                        return;

                break;

        case 1:
                preempt_disable();

                own_fpu();
                if (used_math()) {      /* Using the FPU again.  */
                        restore_fp(current);
                } else {                        /* First time FPU user.  */
                        init_fpu();
                        set_used_math();
                }

                if (cpu_has_fpu) {
                        preempt_enable();
                } else {
                        int sig;
                        preempt_enable();
                        sig = fpu_emulator_cop1Handler(regs,
                                                &current->thread.fpu, 0);
                        if (sig)
                                force_sig(sig, current);
#ifdef CONFIG_MIPS_MT_FPAFF
                        else {
                        /*
                         * 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.
                         */
                         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;

                            cpus_and(tmask,
                                        current->thread.user_cpus_allowed,
                                        mt_fpu_cpumask);
                            set_cpus_allowed(current, tmask);
                            current->thread.mflags |= MF_FPUBOUND;
                          }
                         }
                        }
#endif /* CONFIG_MIPS_MT_FPAFF */
                }

                return;

        case 2:
        case 3:
                die_if_kernel("do_cpu invoked from kernel context!", regs);
                break;
        }

        force_sig(SIGILL, current);
}

asmlinkage void do_mdmx(struct pt_regs *regs)
{
        force_sig(SIGILL, current);
}

asmlinkage void do_watch(struct pt_regs *regs)
{
        /*
         * We use the watch exception where available to detect stack
         * overflows.
         */
        dump_tlb_all();
        show_regs(regs);
        panic("Caught WATCH exception - probably caused by stack overflow.");
}

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

        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 *) 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 Schedulier 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\n");

        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);
}

asmlinkage void do_default_vi(struct pt_regs *regs)
{
        show_regs(regs);
        panic("Caught unexpected vectored interrupt.");
}

/*
 * 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_data.cputype) {
        case CPU_24K:
        case CPU_34K:
        case CPU_5KC:
                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");
        printk("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!");
}

/*
 * 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;
        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;
                regs->cp0_epc = depc;
                __compute_return_epc(regs);
                depc = regs->cp0_epc;
                regs->cp0_epc = old_epc;
        } 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.
 */
void nmi_exception_handler(struct pt_regs *regs)
{
#ifdef CONFIG_MIPS_MT_SMTC
        unsigned long dvpret = dvpe();
        bust_spinlocks(1);
        printk("NMI taken!!!!\n");
        mips_mt_regdump(dvpret);
#else
        bust_spinlocks(1);
        printk("NMI taken!!!!\n");
#endif /* CONFIG_MIPS_MT_SMTC */
        die("NMI", regs);
        while(1) ;
}

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

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

/*
 * As a side effect of the way this is implemented we're limited
 * to interrupt handlers in the address range from
 * KSEG0 <= x < KSEG0 + 256mb on the Nevada.  Oh well ...
 */
void *set_except_vector(int n, void *addr)
{
        unsigned long handler = (unsigned long) addr;
        unsigned long old_handler = exception_handlers[n];

        exception_handlers[n] = handler;
        if (n == 0 && cpu_has_divec) {
                *(volatile u32 *)(ebase + 0x200) = 0x08000000 |
                                                 (0x03ffffff & (handler >> 2));
                flush_icache_range(ebase + 0x200, ebase + 0x204);
        }
        return (void *)old_handler;
}

#ifdef CONFIG_CPU_MIPSR2_SRS
/*
 * MIPSR2 shadow register set allocation
 * FIXME: SMP...
 */

static struct shadow_registers {
        /*
         * Number of shadow register sets supported
         */
        unsigned long sr_supported;
        /*
         * Bitmap of allocated shadow registers
         */
        unsigned long sr_allocated;
} shadow_registers;

static void mips_srs_init(void)
{
        shadow_registers.sr_supported = ((read_c0_srsctl() >> 26) & 0x0f) + 1;
        printk(KERN_INFO "%ld MIPSR2 register sets available\n",
               shadow_registers.sr_supported);
        shadow_registers.sr_allocated = 1;      /* Set 0 used by kernel */
}

int mips_srs_max(void)
{
        return shadow_registers.sr_supported;
}

int mips_srs_alloc(void)
{
        struct shadow_registers *sr = &shadow_registers;
        int set;

again:
        set = find_first_zero_bit(&sr->sr_allocated, sr->sr_supported);
        if (set >= sr->sr_supported)
                return -1;

        if (test_and_set_bit(set, &sr->sr_allocated))
                goto again;

        return set;
}

void mips_srs_free(int set)
{
        struct shadow_registers *sr = &shadow_registers;

        clear_bit(set, &sr->sr_allocated);
}

static void *set_vi_srs_handler(int n, void *addr, int srs)
{
        unsigned long handler;
        unsigned long old_handler = vi_handlers[n];
        u32 *w;
        unsigned char *b;

        if (!cpu_has_veic && !cpu_has_vint)
                BUG();

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

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

        if (srs >= mips_srs_max())
                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 (mips_srs_max() > 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 a standard interrupt exit
                 */

                extern char except_vec_vi, except_vec_vi_lui;
                extern char except_vec_vi_ori, except_vec_vi_end;
#ifdef CONFIG_MIPS_MT_SMTC
                /*
                 * We need to provide the SMTC vectored interrupt handler
                 * not only with the address of the handler, but with the
                 * Status.IM bit to be masked before going there.
                 */
                extern char except_vec_vi_mori;
                const int mori_offset = &except_vec_vi_mori - &except_vec_vi;
#endif /* CONFIG_MIPS_MT_SMTC */
                const int handler_len = &except_vec_vi_end - &except_vec_vi;
                const int lui_offset = &except_vec_vi_lui - &except_vec_vi;
                const int ori_offset = &except_vec_vi_ori - &except_vec_vi;

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

                memcpy (b, &except_vec_vi, handler_len);
#ifdef CONFIG_MIPS_MT_SMTC
                if (n > 7)
                        printk("Vector index %d exceeds SMTC maximum\n", n);
                w = (u32 *)(b + mori_offset);
                *w = (*w & 0xffff0000) | (0x100 << n);
#endif /* CONFIG_MIPS_MT_SMTC */
                w = (u32 *)(b + lui_offset);
                *w = (*w & 0xffff0000) | (((u32)handler >> 16) & 0xffff);
                w = (u32 *)(b + ori_offset);
                *w = (*w & 0xffff0000) | ((u32)handler & 0xffff);
                flush_icache_range((unsigned long)b, (unsigned long)(b+handler_len));
        }
        else {
                /*
                 * In other cases jump directly to the interrupt handler
                 *
                 * It is the handlers responsibility to save registers if required
                 * (eg hi/lo) and return from the exception using "eret"
                 */
                w = (u32 *)b;
                *w++ = 0x08000000 | (((u32)handler >> 2) & 0x03fffff); /* j handler */
                *w = 0;
                flush_icache_range((unsigned long)b, (unsigned long)(b+8));
        }

        return (void *)old_handler;
}

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

#else

static inline void mips_srs_init(void)
{
}

#endif /* CONFIG_CPU_MIPSR2_SRS */

/*
 * This is used by native signal handling
 */
asmlinkage int (*save_fp_context)(struct sigcontext *sc);
asmlinkage int (*restore_fp_context)(struct sigcontext *sc);

extern asmlinkage int _save_fp_context(struct sigcontext *sc);
extern asmlinkage int _restore_fp_context(struct sigcontext *sc);

extern asmlinkage int fpu_emulator_save_context(struct sigcontext *sc);
extern asmlinkage int fpu_emulator_restore_context(struct sigcontext *sc);

#ifdef CONFIG_SMP
static int smp_save_fp_context(struct sigcontext *sc)
{
        return cpu_has_fpu
               ? _save_fp_context(sc)
               : fpu_emulator_save_context(sc);
}

static int smp_restore_fp_context(struct sigcontext *sc)
{
        return cpu_has_fpu
               ? _restore_fp_context(sc)
               : fpu_emulator_restore_context(sc);
}
#endif

static inline void signal_init(void)
{
#ifdef CONFIG_SMP
        /* For now just do the cpu_has_fpu check when the functions are invoked */
        save_fp_context = smp_save_fp_context;
        restore_fp_context = smp_restore_fp_context;
#else
        if (cpu_has_fpu) {
                save_fp_context = _save_fp_context;
                restore_fp_context = _restore_fp_context;
        } else {
                save_fp_context = fpu_emulator_save_context;
                restore_fp_context = fpu_emulator_restore_context;
        }
#endif
}

#ifdef CONFIG_MIPS32_COMPAT

/*
 * This is used by 32-bit signal stuff on the 64-bit kernel
 */
asmlinkage int (*save_fp_context32)(struct sigcontext32 *sc);
asmlinkage int (*restore_fp_context32)(struct sigcontext32 *sc);

extern asmlinkage int _save_fp_context32(struct sigcontext32 *sc);
extern asmlinkage int _restore_fp_context32(struct sigcontext32 *sc);

extern asmlinkage int fpu_emulator_save_context32(struct sigcontext32 *sc);
extern asmlinkage int fpu_emulator_restore_context32(struct sigcontext32 *sc);

static inline void signal32_init(void)
{
        if (cpu_has_fpu) {
                save_fp_context32 = _save_fp_context32;
                restore_fp_context32 = _restore_fp_context32;
        } else {
                save_fp_context32 = fpu_emulator_save_context32;
                restore_fp_context32 = fpu_emulator_restore_context32;
        }
}
#endif

extern void cpu_cache_init(void);
extern void tlb_init(void);
extern void flush_tlb_handlers(void);

void __init per_cpu_trap_init(void)
{
        unsigned int cpu = smp_processor_id();
        unsigned int status_set = ST0_CU0;
#ifdef CONFIG_MIPS_MT_SMTC
        int secondaryTC = 0;
        int bootTC = (cpu == 0);

        /*
         * Only do per_cpu_trap_init() for first TC of Each VPE.
         * Note that this hack assumes that the SMTC init code
         * assigns TCs consecutively and in ascending order.
         */

        if (((read_c0_tcbind() & TCBIND_CURTC) != 0) &&
            ((read_c0_tcbind() & TCBIND_CURVPE) == cpu_data[cpu - 1].vpe_id))
                secondaryTC = 1;
#endif /* CONFIG_MIPS_MT_SMTC */

        /*
         * 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;
        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_dsp)
                set_c0_status(ST0_MX);

#ifdef CONFIG_CPU_MIPSR2
        write_c0_hwrena (0x0000000f); /* Allow rdhwr to all registers */
#endif

#ifdef CONFIG_MIPS_MT_SMTC
        if (!secondaryTC) {
#endif /* CONFIG_MIPS_MT_SMTC */

        /*
         * Interrupt handling.
         */
        if (cpu_has_veic || cpu_has_vint) {
                write_c0_ebase (ebase);
                /* 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);
        }
#ifdef CONFIG_MIPS_MT_SMTC
        }
#endif /* CONFIG_MIPS_MT_SMTC */

        cpu_data[cpu].asid_cache = ASID_FIRST_VERSION;
        TLBMISS_HANDLER_SETUP();

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

#ifdef CONFIG_MIPS_MT_SMTC
        if (bootTC) {
#endif /* CONFIG_MIPS_MT_SMTC */
                cpu_cache_init();
                tlb_init();
#ifdef CONFIG_MIPS_MT_SMTC
        }
#endif /* CONFIG_MIPS_MT_SMTC */
}

/* Install CPU exception handler */
void __init set_handler (unsigned long offset, void *addr, unsigned long size)
{
        memcpy((void *)(ebase + offset), addr, size);
        flush_icache_range(ebase + offset, ebase + offset + size);
}

/* Install uncached CPU exception handler */
void __init set_uncached_handler (unsigned long offset, void *addr, unsigned long size)
{
#ifdef CONFIG_32BIT
        unsigned long uncached_ebase = KSEG1ADDR(ebase);
#endif
#ifdef CONFIG_64BIT
        unsigned long uncached_ebase = TO_UNCAC(ebase);
#endif

        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, except_vec3_r4000;
        extern char except_vec4;
        unsigned long i;

        if (cpu_has_veic || cpu_has_vint)
                ebase = (unsigned long) alloc_bootmem_low_pages (0x200 + VECTORSPACING*64);
        else
                ebase = CAC_BASE;

        mips_srs_init();

        per_cpu_trap_init();

        /*
         * 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, 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);

        if (current_cpu_data.cputype == CPU_R6000 ||
            current_cpu_data.cputype == 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(22, handle_mdmx);

        if (cpu_has_mcheck)
                set_except_vector(24, handle_mcheck);

        if (cpu_has_mipsmt)
                set_except_vector(25, handle_mt);

        if (cpu_has_dsp)
                set_except_vector(26, handle_dsp);

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

        signal_init();
#ifdef CONFIG_MIPS32_COMPAT
        signal32_init();
#endif

        flush_icache_range(ebase, ebase + 0x400);
        flush_tlb_handlers();
}