dst/connector: Disallow unpliviged users to configure dst

[linux-2.6/verdex.git] / arch / mips / mm / tlbex.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.
 *
 * Synthesize TLB refill handlers at runtime.
 *
 * Copyright (C) 2004, 2005, 2006, 2008  Thiemo Seufer
 * Copyright (C) 2005, 2007, 2008, 2009  Maciej W. Rozycki
 * Copyright (C) 2006  Ralf Baechle (ralf@linux-mips.org)
 * Copyright (C) 2008, 2009 Cavium Networks, Inc.
 *
 * ... and the days got worse and worse and now you see
 * I've gone completly out of my mind.
 *
 * They're coming to take me a away haha
 * they're coming to take me a away hoho hihi haha
 * to the funny farm where code is beautiful all the time ...
 *
 * (Condolences to Napoleon XIV)
 */

#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/smp.h>
#include <linux/string.h>
#include <linux/init.h>

#include <asm/mmu_context.h>
#include <asm/war.h>

#include "uasm.h"

static inline int r45k_bvahwbug(void)
{
        /* XXX: We should probe for the presence of this bug, but we don't. */
        return 0;
}

static inline int r4k_250MHZhwbug(void)
{
        /* XXX: We should probe for the presence of this bug, but we don't. */
        return 0;
}

static inline int __maybe_unused bcm1250_m3_war(void)
{
        return BCM1250_M3_WAR;
}

static inline int __maybe_unused r10000_llsc_war(void)
{
        return R10000_LLSC_WAR;
}

/*
 * Found by experiment: At least some revisions of the 4kc throw under
 * some circumstances a machine check exception, triggered by invalid
 * values in the index register.  Delaying the tlbp instruction until
 * after the next branch,  plus adding an additional nop in front of
 * tlbwi/tlbwr avoids the invalid index register values. Nobody knows
 * why; it's not an issue caused by the core RTL.
 *
 */
static int __cpuinit m4kc_tlbp_war(void)
{
        return (current_cpu_data.processor_id & 0xffff00) ==
               (PRID_COMP_MIPS | PRID_IMP_4KC);
}

/* Handle labels (which must be positive integers). */
enum label_id {
        label_second_part = 1,
        label_leave,
#ifdef MODULE_START
        label_module_alloc,
#endif
        label_vmalloc,
        label_vmalloc_done,
        label_tlbw_hazard,
        label_split,
        label_nopage_tlbl,
        label_nopage_tlbs,
        label_nopage_tlbm,
        label_smp_pgtable_change,
        label_r3000_write_probe_fail,
#ifdef CONFIG_HUGETLB_PAGE
        label_tlb_huge_update,
#endif
};

UASM_L_LA(_second_part)
UASM_L_LA(_leave)
#ifdef MODULE_START
UASM_L_LA(_module_alloc)
#endif
UASM_L_LA(_vmalloc)
UASM_L_LA(_vmalloc_done)
UASM_L_LA(_tlbw_hazard)
UASM_L_LA(_split)
UASM_L_LA(_nopage_tlbl)
UASM_L_LA(_nopage_tlbs)
UASM_L_LA(_nopage_tlbm)
UASM_L_LA(_smp_pgtable_change)
UASM_L_LA(_r3000_write_probe_fail)
#ifdef CONFIG_HUGETLB_PAGE
UASM_L_LA(_tlb_huge_update)
#endif

/*
 * For debug purposes.
 */
static inline void dump_handler(const u32 *handler, int count)
{
        int i;

        pr_debug("\t.set push\n");
        pr_debug("\t.set noreorder\n");

        for (i = 0; i < count; i++)
                pr_debug("\t%p\t.word 0x%08x\n", &handler[i], handler[i]);

        pr_debug("\t.set pop\n");
}

/* The only general purpose registers allowed in TLB handlers. */
#define K0              26
#define K1              27

/* Some CP0 registers */
#define C0_INDEX        0, 0
#define C0_ENTRYLO0     2, 0
#define C0_TCBIND       2, 2
#define C0_ENTRYLO1     3, 0
#define C0_CONTEXT      4, 0
#define C0_PAGEMASK     5, 0
#define C0_BADVADDR     8, 0
#define C0_ENTRYHI      10, 0
#define C0_EPC          14, 0
#define C0_XCONTEXT     20, 0

#ifdef CONFIG_64BIT
# define GET_CONTEXT(buf, reg) UASM_i_MFC0(buf, reg, C0_XCONTEXT)
#else
# define GET_CONTEXT(buf, reg) UASM_i_MFC0(buf, reg, C0_CONTEXT)
#endif

/* The worst case length of the handler is around 18 instructions for
 * R3000-style TLBs and up to 63 instructions for R4000-style TLBs.
 * Maximum space available is 32 instructions for R3000 and 64
 * instructions for R4000.
 *
 * We deliberately chose a buffer size of 128, so we won't scribble
 * over anything important on overflow before we panic.
 */
static u32 tlb_handler[128] __cpuinitdata;

/* simply assume worst case size for labels and relocs */
static struct uasm_label labels[128] __cpuinitdata;
static struct uasm_reloc relocs[128] __cpuinitdata;

/*
 * The R3000 TLB handler is simple.
 */
static void __cpuinit build_r3000_tlb_refill_handler(void)
{
        long pgdc = (long)pgd_current;
        u32 *p;

        memset(tlb_handler, 0, sizeof(tlb_handler));
        p = tlb_handler;

        uasm_i_mfc0(&p, K0, C0_BADVADDR);
        uasm_i_lui(&p, K1, uasm_rel_hi(pgdc)); /* cp0 delay */
        uasm_i_lw(&p, K1, uasm_rel_lo(pgdc), K1);
        uasm_i_srl(&p, K0, K0, 22); /* load delay */
        uasm_i_sll(&p, K0, K0, 2);
        uasm_i_addu(&p, K1, K1, K0);
        uasm_i_mfc0(&p, K0, C0_CONTEXT);
        uasm_i_lw(&p, K1, 0, K1); /* cp0 delay */
        uasm_i_andi(&p, K0, K0, 0xffc); /* load delay */
        uasm_i_addu(&p, K1, K1, K0);
        uasm_i_lw(&p, K0, 0, K1);
        uasm_i_nop(&p); /* load delay */
        uasm_i_mtc0(&p, K0, C0_ENTRYLO0);
        uasm_i_mfc0(&p, K1, C0_EPC); /* cp0 delay */
        uasm_i_tlbwr(&p); /* cp0 delay */
        uasm_i_jr(&p, K1);
        uasm_i_rfe(&p); /* branch delay */

        if (p > tlb_handler + 32)
                panic("TLB refill handler space exceeded");

        pr_debug("Wrote TLB refill handler (%u instructions).\n",
                 (unsigned int)(p - tlb_handler));

        memcpy((void *)ebase, tlb_handler, 0x80);

        dump_handler((u32 *)ebase, 32);
}

/*
 * The R4000 TLB handler is much more complicated. We have two
 * consecutive handler areas with 32 instructions space each.
 * Since they aren't used at the same time, we can overflow in the
 * other one.To keep things simple, we first assume linear space,
 * then we relocate it to the final handler layout as needed.
 */
static u32 final_handler[64] __cpuinitdata;

/*
 * Hazards
 *
 * From the IDT errata for the QED RM5230 (Nevada), processor revision 1.0:
 * 2. A timing hazard exists for the TLBP instruction.
 *
 *      stalling_instruction
 *      TLBP
 *
 * The JTLB is being read for the TLBP throughout the stall generated by the
 * previous instruction. This is not really correct as the stalling instruction
 * can modify the address used to access the JTLB.  The failure symptom is that
 * the TLBP instruction will use an address created for the stalling instruction
 * and not the address held in C0_ENHI and thus report the wrong results.
 *
 * The software work-around is to not allow the instruction preceding the TLBP
 * to stall - make it an NOP or some other instruction guaranteed not to stall.
 *
 * Errata 2 will not be fixed.  This errata is also on the R5000.
 *
 * As if we MIPS hackers wouldn't know how to nop pipelines happy ...
 */
static void __cpuinit __maybe_unused build_tlb_probe_entry(u32 **p)
{
        switch (current_cpu_type()) {
        /* Found by experiment: R4600 v2.0/R4700 needs this, too.  */
        case CPU_R4600:
        case CPU_R4700:
        case CPU_R5000:
        case CPU_R5000A:
        case CPU_NEVADA:
                uasm_i_nop(p);
                uasm_i_tlbp(p);
                break;

        default:
                uasm_i_tlbp(p);
                break;
        }
}

/*
 * Write random or indexed TLB entry, and care about the hazards from
 * the preceeding mtc0 and for the following eret.
 */
enum tlb_write_entry { tlb_random, tlb_indexed };

static void __cpuinit build_tlb_write_entry(u32 **p, struct uasm_label **l,
                                         struct uasm_reloc **r,
                                         enum tlb_write_entry wmode)
{
        void(*tlbw)(u32 **) = NULL;

        switch (wmode) {
        case tlb_random: tlbw = uasm_i_tlbwr; break;
        case tlb_indexed: tlbw = uasm_i_tlbwi; break;
        }

        if (cpu_has_mips_r2) {
                if (cpu_has_mips_r2_exec_hazard)
                        uasm_i_ehb(p);
                tlbw(p);
                return;
        }

        switch (current_cpu_type()) {
        case CPU_R4000PC:
        case CPU_R4000SC:
        case CPU_R4000MC:
        case CPU_R4400PC:
        case CPU_R4400SC:
        case CPU_R4400MC:
                /*
                 * This branch uses up a mtc0 hazard nop slot and saves
                 * two nops after the tlbw instruction.
                 */
                uasm_il_bgezl(p, r, 0, label_tlbw_hazard);
                tlbw(p);
                uasm_l_tlbw_hazard(l, *p);
                uasm_i_nop(p);
                break;

        case CPU_R4600:
        case CPU_R4700:
        case CPU_R5000:
        case CPU_R5000A:
                uasm_i_nop(p);
                tlbw(p);
                uasm_i_nop(p);
                break;

        case CPU_R4300:
        case CPU_5KC:
        case CPU_TX49XX:
        case CPU_PR4450:
                uasm_i_nop(p);
                tlbw(p);
                break;

        case CPU_R10000:
        case CPU_R12000:
        case CPU_R14000:
        case CPU_4KC:
        case CPU_4KEC:
        case CPU_SB1:
        case CPU_SB1A:
        case CPU_4KSC:
        case CPU_20KC:
        case CPU_25KF:
        case CPU_BCM3302:
        case CPU_BCM4710:
        case CPU_LOONGSON2:
        case CPU_R5500:
                if (m4kc_tlbp_war())
                        uasm_i_nop(p);
        case CPU_ALCHEMY:
                tlbw(p);
                break;

        case CPU_NEVADA:
                uasm_i_nop(p); /* QED specifies 2 nops hazard */
                /*
                 * This branch uses up a mtc0 hazard nop slot and saves
                 * a nop after the tlbw instruction.
                 */
                uasm_il_bgezl(p, r, 0, label_tlbw_hazard);
                tlbw(p);
                uasm_l_tlbw_hazard(l, *p);
                break;

        case CPU_RM7000:
                uasm_i_nop(p);
                uasm_i_nop(p);
                uasm_i_nop(p);
                uasm_i_nop(p);
                tlbw(p);
                break;

        case CPU_RM9000:
                /*
                 * When the JTLB is updated by tlbwi or tlbwr, a subsequent
                 * use of the JTLB for instructions should not occur for 4
                 * cpu cycles and use for data translations should not occur
                 * for 3 cpu cycles.
                 */
                uasm_i_ssnop(p);
                uasm_i_ssnop(p);
                uasm_i_ssnop(p);
                uasm_i_ssnop(p);
                tlbw(p);
                uasm_i_ssnop(p);
                uasm_i_ssnop(p);
                uasm_i_ssnop(p);
                uasm_i_ssnop(p);
                break;

        case CPU_VR4111:
        case CPU_VR4121:
        case CPU_VR4122:
        case CPU_VR4181:
        case CPU_VR4181A:
                uasm_i_nop(p);
                uasm_i_nop(p);
                tlbw(p);
                uasm_i_nop(p);
                uasm_i_nop(p);
                break;

        case CPU_VR4131:
        case CPU_VR4133:
        case CPU_R5432:
                uasm_i_nop(p);
                uasm_i_nop(p);
                tlbw(p);
                break;

        default:
                panic("No TLB refill handler yet (CPU type: %d)",
                      current_cpu_data.cputype);
                break;
        }
}

#ifdef CONFIG_HUGETLB_PAGE
static __cpuinit void build_huge_tlb_write_entry(u32 **p,
                                                 struct uasm_label **l,
                                                 struct uasm_reloc **r,
                                                 unsigned int tmp,
                                                 enum tlb_write_entry wmode)
{
        /* Set huge page tlb entry size */
        uasm_i_lui(p, tmp, PM_HUGE_MASK >> 16);
        uasm_i_ori(p, tmp, tmp, PM_HUGE_MASK & 0xffff);
        uasm_i_mtc0(p, tmp, C0_PAGEMASK);

        build_tlb_write_entry(p, l, r, wmode);

        /* Reset default page size */
        if (PM_DEFAULT_MASK >> 16) {
                uasm_i_lui(p, tmp, PM_DEFAULT_MASK >> 16);
                uasm_i_ori(p, tmp, tmp, PM_DEFAULT_MASK & 0xffff);
                uasm_il_b(p, r, label_leave);
                uasm_i_mtc0(p, tmp, C0_PAGEMASK);
        } else if (PM_DEFAULT_MASK) {
                uasm_i_ori(p, tmp, 0, PM_DEFAULT_MASK);
                uasm_il_b(p, r, label_leave);
                uasm_i_mtc0(p, tmp, C0_PAGEMASK);
        } else {
                uasm_il_b(p, r, label_leave);
                uasm_i_mtc0(p, 0, C0_PAGEMASK);
        }
}

/*
 * Check if Huge PTE is present, if so then jump to LABEL.
 */
static void __cpuinit
build_is_huge_pte(u32 **p, struct uasm_reloc **r, unsigned int tmp,
                unsigned int pmd, int lid)
{
        UASM_i_LW(p, tmp, 0, pmd);
        uasm_i_andi(p, tmp, tmp, _PAGE_HUGE);
        uasm_il_bnez(p, r, tmp, lid);
}

static __cpuinit void build_huge_update_entries(u32 **p,
                                                unsigned int pte,
                                                unsigned int tmp)
{
        int small_sequence;

        /*
         * A huge PTE describes an area the size of the
         * configured huge page size. This is twice the
         * of the large TLB entry size we intend to use.
         * A TLB entry half the size of the configured
         * huge page size is configured into entrylo0
         * and entrylo1 to cover the contiguous huge PTE
         * address space.
         */
        small_sequence = (HPAGE_SIZE >> 7) < 0x10000;

        /* We can clobber tmp.  It isn't used after this.*/
        if (!small_sequence)
                uasm_i_lui(p, tmp, HPAGE_SIZE >> (7 + 16));

        UASM_i_SRL(p, pte, pte, 6); /* convert to entrylo */
        uasm_i_mtc0(p, pte, C0_ENTRYLO0); /* load it */
        /* convert to entrylo1 */
        if (small_sequence)
                UASM_i_ADDIU(p, pte, pte, HPAGE_SIZE >> 7);
        else
                UASM_i_ADDU(p, pte, pte, tmp);

        uasm_i_mtc0(p, pte, C0_ENTRYLO1); /* load it */
}

static __cpuinit void build_huge_handler_tail(u32 **p,
                                              struct uasm_reloc **r,
                                              struct uasm_label **l,
                                              unsigned int pte,
                                              unsigned int ptr)
{
#ifdef CONFIG_SMP
        UASM_i_SC(p, pte, 0, ptr);
        uasm_il_beqz(p, r, pte, label_tlb_huge_update);
        UASM_i_LW(p, pte, 0, ptr); /* Needed because SC killed our PTE */
#else
        UASM_i_SW(p, pte, 0, ptr);
#endif
        build_huge_update_entries(p, pte, ptr);
        build_huge_tlb_write_entry(p, l, r, pte, tlb_indexed);
}
#endif /* CONFIG_HUGETLB_PAGE */

#ifdef CONFIG_64BIT
/*
 * TMP and PTR are scratch.
 * TMP will be clobbered, PTR will hold the pmd entry.
 */
static void __cpuinit
build_get_pmde64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
                 unsigned int tmp, unsigned int ptr)
{
        long pgdc = (long)pgd_current;

        /*
         * The vmalloc handling is not in the hotpath.
         */
        uasm_i_dmfc0(p, tmp, C0_BADVADDR);
#ifdef MODULE_START
        uasm_il_bltz(p, r, tmp, label_module_alloc);
#else
        uasm_il_bltz(p, r, tmp, label_vmalloc);
#endif
        /* No uasm_i_nop needed here, since the next insn doesn't touch TMP. */

#ifdef CONFIG_SMP
# ifdef  CONFIG_MIPS_MT_SMTC
        /*
         * SMTC uses TCBind value as "CPU" index
         */
        uasm_i_mfc0(p, ptr, C0_TCBIND);
        uasm_i_dsrl(p, ptr, ptr, 19);
# else
        /*
         * 64 bit SMP running in XKPHYS has smp_processor_id() << 3
         * stored in CONTEXT.
         */
        uasm_i_dmfc0(p, ptr, C0_CONTEXT);
        uasm_i_dsrl(p, ptr, ptr, 23);
#endif
        UASM_i_LA_mostly(p, tmp, pgdc);
        uasm_i_daddu(p, ptr, ptr, tmp);
        uasm_i_dmfc0(p, tmp, C0_BADVADDR);
        uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
#else
        UASM_i_LA_mostly(p, ptr, pgdc);
        uasm_i_ld(p, ptr, uasm_rel_lo(pgdc), ptr);
#endif

        uasm_l_vmalloc_done(l, *p);

        if (PGDIR_SHIFT - 3 < 32)               /* get pgd offset in bytes */
                uasm_i_dsrl(p, tmp, tmp, PGDIR_SHIFT-3);
        else
                uasm_i_dsrl32(p, tmp, tmp, PGDIR_SHIFT - 3 - 32);

        uasm_i_andi(p, tmp, tmp, (PTRS_PER_PGD - 1)<<3);
        uasm_i_daddu(p, ptr, ptr, tmp); /* add in pgd offset */
        uasm_i_dmfc0(p, tmp, C0_BADVADDR); /* get faulting address */
        uasm_i_ld(p, ptr, 0, ptr); /* get pmd pointer */
        uasm_i_dsrl(p, tmp, tmp, PMD_SHIFT-3); /* get pmd offset in bytes */
        uasm_i_andi(p, tmp, tmp, (PTRS_PER_PMD - 1)<<3);
        uasm_i_daddu(p, ptr, ptr, tmp); /* add in pmd offset */
}

/*
 * BVADDR is the faulting address, PTR is scratch.
 * PTR will hold the pgd for vmalloc.
 */
static void __cpuinit
build_get_pgd_vmalloc64(u32 **p, struct uasm_label **l, struct uasm_reloc **r,
                        unsigned int bvaddr, unsigned int ptr)
{
        long swpd = (long)swapper_pg_dir;

#ifdef MODULE_START
        long modd = (long)module_pg_dir;

        uasm_l_module_alloc(l, *p);
        /*
         * Assumption:
         * VMALLOC_START >= 0xc000000000000000UL
         * MODULE_START >= 0xe000000000000000UL
         */
        UASM_i_SLL(p, ptr, bvaddr, 2);
        uasm_il_bgez(p, r, ptr, label_vmalloc);

        if (uasm_in_compat_space_p(MODULE_START) &&
            !uasm_rel_lo(MODULE_START)) {
                uasm_i_lui(p, ptr, uasm_rel_hi(MODULE_START)); /* delay slot */
        } else {
                /* unlikely configuration */
                uasm_i_nop(p); /* delay slot */
                UASM_i_LA(p, ptr, MODULE_START);
        }
        uasm_i_dsubu(p, bvaddr, bvaddr, ptr);

        if (uasm_in_compat_space_p(modd) && !uasm_rel_lo(modd)) {
                uasm_il_b(p, r, label_vmalloc_done);
                uasm_i_lui(p, ptr, uasm_rel_hi(modd));
        } else {
                UASM_i_LA_mostly(p, ptr, modd);
                uasm_il_b(p, r, label_vmalloc_done);
                if (uasm_in_compat_space_p(modd))
                        uasm_i_addiu(p, ptr, ptr, uasm_rel_lo(modd));
                else
                        uasm_i_daddiu(p, ptr, ptr, uasm_rel_lo(modd));
        }

        uasm_l_vmalloc(l, *p);
        if (uasm_in_compat_space_p(MODULE_START) &&
            !uasm_rel_lo(MODULE_START) &&
            MODULE_START << 32 == VMALLOC_START)
                uasm_i_dsll32(p, ptr, ptr, 0);  /* typical case */
        else
                UASM_i_LA(p, ptr, VMALLOC_START);
#else
        uasm_l_vmalloc(l, *p);
        UASM_i_LA(p, ptr, VMALLOC_START);
#endif
        uasm_i_dsubu(p, bvaddr, bvaddr, ptr);

        if (uasm_in_compat_space_p(swpd) && !uasm_rel_lo(swpd)) {
                uasm_il_b(p, r, label_vmalloc_done);
                uasm_i_lui(p, ptr, uasm_rel_hi(swpd));
        } else {
                UASM_i_LA_mostly(p, ptr, swpd);
                uasm_il_b(p, r, label_vmalloc_done);
                if (uasm_in_compat_space_p(swpd))
                        uasm_i_addiu(p, ptr, ptr, uasm_rel_lo(swpd));
                else
                        uasm_i_daddiu(p, ptr, ptr, uasm_rel_lo(swpd));
        }
}

#else /* !CONFIG_64BIT */

/*
 * TMP and PTR are scratch.
 * TMP will be clobbered, PTR will hold the pgd entry.
 */
static void __cpuinit __maybe_unused
build_get_pgde32(u32 **p, unsigned int tmp, unsigned int ptr)
{
        long pgdc = (long)pgd_current;

        /* 32 bit SMP has smp_processor_id() stored in CONTEXT. */
#ifdef CONFIG_SMP
#ifdef  CONFIG_MIPS_MT_SMTC
        /*
         * SMTC uses TCBind value as "CPU" index
         */
        uasm_i_mfc0(p, ptr, C0_TCBIND);
        UASM_i_LA_mostly(p, tmp, pgdc);
        uasm_i_srl(p, ptr, ptr, 19);
#else
        /*
         * smp_processor_id() << 3 is stored in CONTEXT.
         */
        uasm_i_mfc0(p, ptr, C0_CONTEXT);
        UASM_i_LA_mostly(p, tmp, pgdc);
        uasm_i_srl(p, ptr, ptr, 23);
#endif
        uasm_i_addu(p, ptr, tmp, ptr);
#else
        UASM_i_LA_mostly(p, ptr, pgdc);
#endif
        uasm_i_mfc0(p, tmp, C0_BADVADDR); /* get faulting address */
        uasm_i_lw(p, ptr, uasm_rel_lo(pgdc), ptr);
        uasm_i_srl(p, tmp, tmp, PGDIR_SHIFT); /* get pgd only bits */
        uasm_i_sll(p, tmp, tmp, PGD_T_LOG2);
        uasm_i_addu(p, ptr, ptr, tmp); /* add in pgd offset */
}

#endif /* !CONFIG_64BIT */

static void __cpuinit build_adjust_context(u32 **p, unsigned int ctx)
{
        unsigned int shift = 4 - (PTE_T_LOG2 + 1) + PAGE_SHIFT - 12;
        unsigned int mask = (PTRS_PER_PTE / 2 - 1) << (PTE_T_LOG2 + 1);

        switch (current_cpu_type()) {
        case CPU_VR41XX:
        case CPU_VR4111:
        case CPU_VR4121:
        case CPU_VR4122:
        case CPU_VR4131:
        case CPU_VR4181:
        case CPU_VR4181A:
        case CPU_VR4133:
                shift += 2;
                break;

        default:
                break;
        }

        if (shift)
                UASM_i_SRL(p, ctx, ctx, shift);
        uasm_i_andi(p, ctx, ctx, mask);
}

static void __cpuinit build_get_ptep(u32 **p, unsigned int tmp, unsigned int ptr)
{
        /*
         * Bug workaround for the Nevada. It seems as if under certain
         * circumstances the move from cp0_context might produce a
         * bogus result when the mfc0 instruction and its consumer are
         * in a different cacheline or a load instruction, probably any
         * memory reference, is between them.
         */
        switch (current_cpu_type()) {
        case CPU_NEVADA:
                UASM_i_LW(p, ptr, 0, ptr);
                GET_CONTEXT(p, tmp); /* get context reg */
                break;

        default:
                GET_CONTEXT(p, tmp); /* get context reg */
                UASM_i_LW(p, ptr, 0, ptr);
                break;
        }

        build_adjust_context(p, tmp);
        UASM_i_ADDU(p, ptr, ptr, tmp); /* add in offset */
}

static void __cpuinit build_update_entries(u32 **p, unsigned int tmp,
                                        unsigned int ptep)
{
        /*
         * 64bit address support (36bit on a 32bit CPU) in a 32bit
         * Kernel is a special case. Only a few CPUs use it.
         */
#ifdef CONFIG_64BIT_PHYS_ADDR
        if (cpu_has_64bits) {
                uasm_i_ld(p, tmp, 0, ptep); /* get even pte */
                uasm_i_ld(p, ptep, sizeof(pte_t), ptep); /* get odd pte */
                uasm_i_dsrl(p, tmp, tmp, 6); /* convert to entrylo0 */
                uasm_i_mtc0(p, tmp, C0_ENTRYLO0); /* load it */
                uasm_i_dsrl(p, ptep, ptep, 6); /* convert to entrylo1 */
                uasm_i_mtc0(p, ptep, C0_ENTRYLO1); /* load it */
        } else {
                int pte_off_even = sizeof(pte_t) / 2;
                int pte_off_odd = pte_off_even + sizeof(pte_t);

                /* The pte entries are pre-shifted */
                uasm_i_lw(p, tmp, pte_off_even, ptep); /* get even pte */
                uasm_i_mtc0(p, tmp, C0_ENTRYLO0); /* load it */
                uasm_i_lw(p, ptep, pte_off_odd, ptep); /* get odd pte */
                uasm_i_mtc0(p, ptep, C0_ENTRYLO1); /* load it */
        }
#else
        UASM_i_LW(p, tmp, 0, ptep); /* get even pte */
        UASM_i_LW(p, ptep, sizeof(pte_t), ptep); /* get odd pte */
        if (r45k_bvahwbug())
                build_tlb_probe_entry(p);
        UASM_i_SRL(p, tmp, tmp, 6); /* convert to entrylo0 */
        if (r4k_250MHZhwbug())
                uasm_i_mtc0(p, 0, C0_ENTRYLO0);
        uasm_i_mtc0(p, tmp, C0_ENTRYLO0); /* load it */
        UASM_i_SRL(p, ptep, ptep, 6); /* convert to entrylo1 */
        if (r45k_bvahwbug())
                uasm_i_mfc0(p, tmp, C0_INDEX);
        if (r4k_250MHZhwbug())
                uasm_i_mtc0(p, 0, C0_ENTRYLO1);
        uasm_i_mtc0(p, ptep, C0_ENTRYLO1); /* load it */
#endif
}

/*
 * For a 64-bit kernel, we are using the 64-bit XTLB refill exception
 * because EXL == 0.  If we wrap, we can also use the 32 instruction
 * slots before the XTLB refill exception handler which belong to the
 * unused TLB refill exception.
 */
#define MIPS64_REFILL_INSNS 32

static void __cpuinit build_r4000_tlb_refill_handler(void)
{
        u32 *p = tlb_handler;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;
        u32 *f;
        unsigned int final_len;

        memset(tlb_handler, 0, sizeof(tlb_handler));
        memset(labels, 0, sizeof(labels));
        memset(relocs, 0, sizeof(relocs));
        memset(final_handler, 0, sizeof(final_handler));

        /*
         * create the plain linear handler
         */
        if (bcm1250_m3_war()) {
                UASM_i_MFC0(&p, K0, C0_BADVADDR);
                UASM_i_MFC0(&p, K1, C0_ENTRYHI);
                uasm_i_xor(&p, K0, K0, K1);
                UASM_i_SRL(&p, K0, K0, PAGE_SHIFT + 1);
                uasm_il_bnez(&p, &r, K0, label_leave);
                /* No need for uasm_i_nop */
        }

#ifdef CONFIG_64BIT
        build_get_pmde64(&p, &l, &r, K0, K1); /* get pmd in K1 */
#else
        build_get_pgde32(&p, K0, K1); /* get pgd in K1 */
#endif

#ifdef CONFIG_HUGETLB_PAGE
        build_is_huge_pte(&p, &r, K0, K1, label_tlb_huge_update);
#endif

        build_get_ptep(&p, K0, K1);
        build_update_entries(&p, K0, K1);
        build_tlb_write_entry(&p, &l, &r, tlb_random);
        uasm_l_leave(&l, p);
        uasm_i_eret(&p); /* return from trap */

#ifdef CONFIG_HUGETLB_PAGE
        uasm_l_tlb_huge_update(&l, p);
        UASM_i_LW(&p, K0, 0, K1);
        build_huge_update_entries(&p, K0, K1);
        build_huge_tlb_write_entry(&p, &l, &r, K0, tlb_random);
#endif

#ifdef CONFIG_64BIT
        build_get_pgd_vmalloc64(&p, &l, &r, K0, K1);
#endif

        /*
         * Overflow check: For the 64bit handler, we need at least one
         * free instruction slot for the wrap-around branch. In worst
         * case, if the intended insertion point is a delay slot, we
         * need three, with the second nop'ed and the third being
         * unused.
         */
        /* Loongson2 ebase is different than r4k, we have more space */
#if defined(CONFIG_32BIT) || defined(CONFIG_CPU_LOONGSON2)
        if ((p - tlb_handler) > 64)
                panic("TLB refill handler space exceeded");
#else
        if (((p - tlb_handler) > (MIPS64_REFILL_INSNS * 2) - 1)
            || (((p - tlb_handler) > (MIPS64_REFILL_INSNS * 2) - 3)
                && uasm_insn_has_bdelay(relocs,
                                        tlb_handler + MIPS64_REFILL_INSNS - 3)))
                panic("TLB refill handler space exceeded");
#endif

        /*
         * Now fold the handler in the TLB refill handler space.
         */
#if defined(CONFIG_32BIT) || defined(CONFIG_CPU_LOONGSON2)
        f = final_handler;
        /* Simplest case, just copy the handler. */
        uasm_copy_handler(relocs, labels, tlb_handler, p, f);
        final_len = p - tlb_handler;
#else /* CONFIG_64BIT */
        f = final_handler + MIPS64_REFILL_INSNS;
        if ((p - tlb_handler) <= MIPS64_REFILL_INSNS) {
                /* Just copy the handler. */
                uasm_copy_handler(relocs, labels, tlb_handler, p, f);
                final_len = p - tlb_handler;
        } else {
#if defined(CONFIG_HUGETLB_PAGE)
                const enum label_id ls = label_tlb_huge_update;
#elif defined(MODULE_START)
                const enum label_id ls = label_module_alloc;
#else
                const enum label_id ls = label_vmalloc;
#endif
                u32 *split;
                int ov = 0;
                int i;

                for (i = 0; i < ARRAY_SIZE(labels) && labels[i].lab != ls; i++)
                        ;
                BUG_ON(i == ARRAY_SIZE(labels));
                split = labels[i].addr;

                /*
                 * See if we have overflown one way or the other.
                 */
                if (split > tlb_handler + MIPS64_REFILL_INSNS ||
                    split < p - MIPS64_REFILL_INSNS)
                        ov = 1;

                if (ov) {
                        /*
                         * Split two instructions before the end.  One
                         * for the branch and one for the instruction
                         * in the delay slot.
                         */
                        split = tlb_handler + MIPS64_REFILL_INSNS - 2;

                        /*
                         * If the branch would fall in a delay slot,
                         * we must back up an additional instruction
                         * so that it is no longer in a delay slot.
                         */
                        if (uasm_insn_has_bdelay(relocs, split - 1))
                                split--;
                }
                /* Copy first part of the handler. */
                uasm_copy_handler(relocs, labels, tlb_handler, split, f);
                f += split - tlb_handler;

                if (ov) {
                        /* Insert branch. */
                        uasm_l_split(&l, final_handler);
                        uasm_il_b(&f, &r, label_split);
                        if (uasm_insn_has_bdelay(relocs, split))
                                uasm_i_nop(&f);
                        else {
                                uasm_copy_handler(relocs, labels,
                                                  split, split + 1, f);
                                uasm_move_labels(labels, f, f + 1, -1);
                                f++;
                                split++;
                        }
                }

                /* Copy the rest of the handler. */
                uasm_copy_handler(relocs, labels, split, p, final_handler);
                final_len = (f - (final_handler + MIPS64_REFILL_INSNS)) +
                            (p - split);
        }
#endif /* CONFIG_64BIT */

        uasm_resolve_relocs(relocs, labels);
        pr_debug("Wrote TLB refill handler (%u instructions).\n",
                 final_len);

        memcpy((void *)ebase, final_handler, 0x100);

        dump_handler((u32 *)ebase, 64);
}

/*
 * TLB load/store/modify handlers.
 *
 * Only the fastpath gets synthesized at runtime, the slowpath for
 * do_page_fault remains normal asm.
 */
extern void tlb_do_page_fault_0(void);
extern void tlb_do_page_fault_1(void);

/*
 * 128 instructions for the fastpath handler is generous and should
 * never be exceeded.
 */
#define FASTPATH_SIZE 128

u32 handle_tlbl[FASTPATH_SIZE] __cacheline_aligned;
u32 handle_tlbs[FASTPATH_SIZE] __cacheline_aligned;
u32 handle_tlbm[FASTPATH_SIZE] __cacheline_aligned;

static void __cpuinit
iPTE_LW(u32 **p, unsigned int pte, unsigned int ptr)
{
#ifdef CONFIG_SMP
# ifdef CONFIG_64BIT_PHYS_ADDR
        if (cpu_has_64bits)
                uasm_i_lld(p, pte, 0, ptr);
        else
# endif
                UASM_i_LL(p, pte, 0, ptr);
#else
# ifdef CONFIG_64BIT_PHYS_ADDR
        if (cpu_has_64bits)
                uasm_i_ld(p, pte, 0, ptr);
        else
# endif
                UASM_i_LW(p, pte, 0, ptr);
#endif
}

static void __cpuinit
iPTE_SW(u32 **p, struct uasm_reloc **r, unsigned int pte, unsigned int ptr,
        unsigned int mode)
{
#ifdef CONFIG_64BIT_PHYS_ADDR
        unsigned int hwmode = mode & (_PAGE_VALID | _PAGE_DIRTY);
#endif

        uasm_i_ori(p, pte, pte, mode);
#ifdef CONFIG_SMP
# ifdef CONFIG_64BIT_PHYS_ADDR
        if (cpu_has_64bits)
                uasm_i_scd(p, pte, 0, ptr);
        else
# endif
                UASM_i_SC(p, pte, 0, ptr);

        if (r10000_llsc_war())
                uasm_il_beqzl(p, r, pte, label_smp_pgtable_change);
        else
                uasm_il_beqz(p, r, pte, label_smp_pgtable_change);

# ifdef CONFIG_64BIT_PHYS_ADDR
        if (!cpu_has_64bits) {
                /* no uasm_i_nop needed */
                uasm_i_ll(p, pte, sizeof(pte_t) / 2, ptr);
                uasm_i_ori(p, pte, pte, hwmode);
                uasm_i_sc(p, pte, sizeof(pte_t) / 2, ptr);
                uasm_il_beqz(p, r, pte, label_smp_pgtable_change);
                /* no uasm_i_nop needed */
                uasm_i_lw(p, pte, 0, ptr);
        } else
                uasm_i_nop(p);
# else
        uasm_i_nop(p);
# endif
#else
# ifdef CONFIG_64BIT_PHYS_ADDR
        if (cpu_has_64bits)
                uasm_i_sd(p, pte, 0, ptr);
        else
# endif
                UASM_i_SW(p, pte, 0, ptr);

# ifdef CONFIG_64BIT_PHYS_ADDR
        if (!cpu_has_64bits) {
                uasm_i_lw(p, pte, sizeof(pte_t) / 2, ptr);
                uasm_i_ori(p, pte, pte, hwmode);
                uasm_i_sw(p, pte, sizeof(pte_t) / 2, ptr);
                uasm_i_lw(p, pte, 0, ptr);
        }
# endif
#endif
}

/*
 * Check if PTE is present, if not then jump to LABEL. PTR points to
 * the page table where this PTE is located, PTE will be re-loaded
 * with it's original value.
 */
static void __cpuinit
build_pte_present(u32 **p, struct uasm_reloc **r,
                  unsigned int pte, unsigned int ptr, enum label_id lid)
{
        uasm_i_andi(p, pte, pte, _PAGE_PRESENT | _PAGE_READ);
        uasm_i_xori(p, pte, pte, _PAGE_PRESENT | _PAGE_READ);
        uasm_il_bnez(p, r, pte, lid);
        iPTE_LW(p, pte, ptr);
}

/* Make PTE valid, store result in PTR. */
static void __cpuinit
build_make_valid(u32 **p, struct uasm_reloc **r, unsigned int pte,
                 unsigned int ptr)
{
        unsigned int mode = _PAGE_VALID | _PAGE_ACCESSED;

        iPTE_SW(p, r, pte, ptr, mode);
}

/*
 * Check if PTE can be written to, if not branch to LABEL. Regardless
 * restore PTE with value from PTR when done.
 */
static void __cpuinit
build_pte_writable(u32 **p, struct uasm_reloc **r,
                   unsigned int pte, unsigned int ptr, enum label_id lid)
{
        uasm_i_andi(p, pte, pte, _PAGE_PRESENT | _PAGE_WRITE);
        uasm_i_xori(p, pte, pte, _PAGE_PRESENT | _PAGE_WRITE);
        uasm_il_bnez(p, r, pte, lid);
        iPTE_LW(p, pte, ptr);
}

/* Make PTE writable, update software status bits as well, then store
 * at PTR.
 */
static void __cpuinit
build_make_write(u32 **p, struct uasm_reloc **r, unsigned int pte,
                 unsigned int ptr)
{
        unsigned int mode = (_PAGE_ACCESSED | _PAGE_MODIFIED | _PAGE_VALID
                             | _PAGE_DIRTY);

        iPTE_SW(p, r, pte, ptr, mode);
}

/*
 * Check if PTE can be modified, if not branch to LABEL. Regardless
 * restore PTE with value from PTR when done.
 */
static void __cpuinit
build_pte_modifiable(u32 **p, struct uasm_reloc **r,
                     unsigned int pte, unsigned int ptr, enum label_id lid)
{
        uasm_i_andi(p, pte, pte, _PAGE_WRITE);
        uasm_il_beqz(p, r, pte, lid);
        iPTE_LW(p, pte, ptr);
}

/*
 * R3000 style TLB load/store/modify handlers.
 */

/*
 * This places the pte into ENTRYLO0 and writes it with tlbwi.
 * Then it returns.
 */
static void __cpuinit
build_r3000_pte_reload_tlbwi(u32 **p, unsigned int pte, unsigned int tmp)
{
        uasm_i_mtc0(p, pte, C0_ENTRYLO0); /* cp0 delay */
        uasm_i_mfc0(p, tmp, C0_EPC); /* cp0 delay */
        uasm_i_tlbwi(p);
        uasm_i_jr(p, tmp);
        uasm_i_rfe(p); /* branch delay */
}

/*
 * This places the pte into ENTRYLO0 and writes it with tlbwi
 * or tlbwr as appropriate.  This is because the index register
 * may have the probe fail bit set as a result of a trap on a
 * kseg2 access, i.e. without refill.  Then it returns.
 */
static void __cpuinit
build_r3000_tlb_reload_write(u32 **p, struct uasm_label **l,
                             struct uasm_reloc **r, unsigned int pte,
                             unsigned int tmp)
{
        uasm_i_mfc0(p, tmp, C0_INDEX);
        uasm_i_mtc0(p, pte, C0_ENTRYLO0); /* cp0 delay */
        uasm_il_bltz(p, r, tmp, label_r3000_write_probe_fail); /* cp0 delay */
        uasm_i_mfc0(p, tmp, C0_EPC); /* branch delay */
        uasm_i_tlbwi(p); /* cp0 delay */
        uasm_i_jr(p, tmp);
        uasm_i_rfe(p); /* branch delay */
        uasm_l_r3000_write_probe_fail(l, *p);
        uasm_i_tlbwr(p); /* cp0 delay */
        uasm_i_jr(p, tmp);
        uasm_i_rfe(p); /* branch delay */
}

static void __cpuinit
build_r3000_tlbchange_handler_head(u32 **p, unsigned int pte,
                                   unsigned int ptr)
{
        long pgdc = (long)pgd_current;

        uasm_i_mfc0(p, pte, C0_BADVADDR);
        uasm_i_lui(p, ptr, uasm_rel_hi(pgdc)); /* cp0 delay */
        uasm_i_lw(p, ptr, uasm_rel_lo(pgdc), ptr);
        uasm_i_srl(p, pte, pte, 22); /* load delay */
        uasm_i_sll(p, pte, pte, 2);
        uasm_i_addu(p, ptr, ptr, pte);
        uasm_i_mfc0(p, pte, C0_CONTEXT);
        uasm_i_lw(p, ptr, 0, ptr); /* cp0 delay */
        uasm_i_andi(p, pte, pte, 0xffc); /* load delay */
        uasm_i_addu(p, ptr, ptr, pte);
        uasm_i_lw(p, pte, 0, ptr);
        uasm_i_tlbp(p); /* load delay */
}

static void __cpuinit build_r3000_tlb_load_handler(void)
{
        u32 *p = handle_tlbl;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;

        memset(handle_tlbl, 0, sizeof(handle_tlbl));
        memset(labels, 0, sizeof(labels));
        memset(relocs, 0, sizeof(relocs));

        build_r3000_tlbchange_handler_head(&p, K0, K1);
        build_pte_present(&p, &r, K0, K1, label_nopage_tlbl);
        uasm_i_nop(&p); /* load delay */
        build_make_valid(&p, &r, K0, K1);
        build_r3000_tlb_reload_write(&p, &l, &r, K0, K1);

        uasm_l_nopage_tlbl(&l, p);
        uasm_i_j(&p, (unsigned long)tlb_do_page_fault_0 & 0x0fffffff);
        uasm_i_nop(&p);

        if ((p - handle_tlbl) > FASTPATH_SIZE)
                panic("TLB load handler fastpath space exceeded");

        uasm_resolve_relocs(relocs, labels);
        pr_debug("Wrote TLB load handler fastpath (%u instructions).\n",
                 (unsigned int)(p - handle_tlbl));

        dump_handler(handle_tlbl, ARRAY_SIZE(handle_tlbl));
}

static void __cpuinit build_r3000_tlb_store_handler(void)
{
        u32 *p = handle_tlbs;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;

        memset(handle_tlbs, 0, sizeof(handle_tlbs));
        memset(labels, 0, sizeof(labels));
        memset(relocs, 0, sizeof(relocs));

        build_r3000_tlbchange_handler_head(&p, K0, K1);
        build_pte_writable(&p, &r, K0, K1, label_nopage_tlbs);
        uasm_i_nop(&p); /* load delay */
        build_make_write(&p, &r, K0, K1);
        build_r3000_tlb_reload_write(&p, &l, &r, K0, K1);

        uasm_l_nopage_tlbs(&l, p);
        uasm_i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);
        uasm_i_nop(&p);

        if ((p - handle_tlbs) > FASTPATH_SIZE)
                panic("TLB store handler fastpath space exceeded");

        uasm_resolve_relocs(relocs, labels);
        pr_debug("Wrote TLB store handler fastpath (%u instructions).\n",
                 (unsigned int)(p - handle_tlbs));

        dump_handler(handle_tlbs, ARRAY_SIZE(handle_tlbs));
}

static void __cpuinit build_r3000_tlb_modify_handler(void)
{
        u32 *p = handle_tlbm;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;

        memset(handle_tlbm, 0, sizeof(handle_tlbm));
        memset(labels, 0, sizeof(labels));
        memset(relocs, 0, sizeof(relocs));

        build_r3000_tlbchange_handler_head(&p, K0, K1);
        build_pte_modifiable(&p, &r, K0, K1, label_nopage_tlbm);
        uasm_i_nop(&p); /* load delay */
        build_make_write(&p, &r, K0, K1);
        build_r3000_pte_reload_tlbwi(&p, K0, K1);

        uasm_l_nopage_tlbm(&l, p);
        uasm_i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);
        uasm_i_nop(&p);

        if ((p - handle_tlbm) > FASTPATH_SIZE)
                panic("TLB modify handler fastpath space exceeded");

        uasm_resolve_relocs(relocs, labels);
        pr_debug("Wrote TLB modify handler fastpath (%u instructions).\n",
                 (unsigned int)(p - handle_tlbm));

        dump_handler(handle_tlbm, ARRAY_SIZE(handle_tlbm));
}

/*
 * R4000 style TLB load/store/modify handlers.
 */
static void __cpuinit
build_r4000_tlbchange_handler_head(u32 **p, struct uasm_label **l,
                                   struct uasm_reloc **r, unsigned int pte,
                                   unsigned int ptr)
{
#ifdef CONFIG_64BIT
        build_get_pmde64(p, l, r, pte, ptr); /* get pmd in ptr */
#else
        build_get_pgde32(p, pte, ptr); /* get pgd in ptr */
#endif

#ifdef CONFIG_HUGETLB_PAGE
        /*
         * For huge tlb entries, pmd doesn't contain an address but
         * instead contains the tlb pte. Check the PAGE_HUGE bit and
         * see if we need to jump to huge tlb processing.
         */
        build_is_huge_pte(p, r, pte, ptr, label_tlb_huge_update);
#endif

        UASM_i_MFC0(p, pte, C0_BADVADDR);
        UASM_i_LW(p, ptr, 0, ptr);
        UASM_i_SRL(p, pte, pte, PAGE_SHIFT + PTE_ORDER - PTE_T_LOG2);
        uasm_i_andi(p, pte, pte, (PTRS_PER_PTE - 1) << PTE_T_LOG2);
        UASM_i_ADDU(p, ptr, ptr, pte);

#ifdef CONFIG_SMP
        uasm_l_smp_pgtable_change(l, *p);
#endif
        iPTE_LW(p, pte, ptr); /* get even pte */
        if (!m4kc_tlbp_war())
                build_tlb_probe_entry(p);
}

static void __cpuinit
build_r4000_tlbchange_handler_tail(u32 **p, struct uasm_label **l,
                                   struct uasm_reloc **r, unsigned int tmp,
                                   unsigned int ptr)
{
        uasm_i_ori(p, ptr, ptr, sizeof(pte_t));
        uasm_i_xori(p, ptr, ptr, sizeof(pte_t));
        build_update_entries(p, tmp, ptr);
        build_tlb_write_entry(p, l, r, tlb_indexed);
        uasm_l_leave(l, *p);
        uasm_i_eret(p); /* return from trap */

#ifdef CONFIG_64BIT
        build_get_pgd_vmalloc64(p, l, r, tmp, ptr);
#endif
}

static void __cpuinit build_r4000_tlb_load_handler(void)
{
        u32 *p = handle_tlbl;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;

        memset(handle_tlbl, 0, sizeof(handle_tlbl));
        memset(labels, 0, sizeof(labels));
        memset(relocs, 0, sizeof(relocs));

        if (bcm1250_m3_war()) {
                UASM_i_MFC0(&p, K0, C0_BADVADDR);
                UASM_i_MFC0(&p, K1, C0_ENTRYHI);
                uasm_i_xor(&p, K0, K0, K1);
                UASM_i_SRL(&p, K0, K0, PAGE_SHIFT + 1);
                uasm_il_bnez(&p, &r, K0, label_leave);
                /* No need for uasm_i_nop */
        }

        build_r4000_tlbchange_handler_head(&p, &l, &r, K0, K1);
        build_pte_present(&p, &r, K0, K1, label_nopage_tlbl);
        if (m4kc_tlbp_war())
                build_tlb_probe_entry(&p);
        build_make_valid(&p, &r, K0, K1);
        build_r4000_tlbchange_handler_tail(&p, &l, &r, K0, K1);

#ifdef CONFIG_HUGETLB_PAGE
        /*
         * This is the entry point when build_r4000_tlbchange_handler_head
         * spots a huge page.
         */
        uasm_l_tlb_huge_update(&l, p);
        iPTE_LW(&p, K0, K1);
        build_pte_present(&p, &r, K0, K1, label_nopage_tlbl);
        build_tlb_probe_entry(&p);
        uasm_i_ori(&p, K0, K0, (_PAGE_ACCESSED | _PAGE_VALID));
        build_huge_handler_tail(&p, &r, &l, K0, K1);
#endif

        uasm_l_nopage_tlbl(&l, p);
        uasm_i_j(&p, (unsigned long)tlb_do_page_fault_0 & 0x0fffffff);
        uasm_i_nop(&p);

        if ((p - handle_tlbl) > FASTPATH_SIZE)
                panic("TLB load handler fastpath space exceeded");

        uasm_resolve_relocs(relocs, labels);
        pr_debug("Wrote TLB load handler fastpath (%u instructions).\n",
                 (unsigned int)(p - handle_tlbl));

        dump_handler(handle_tlbl, ARRAY_SIZE(handle_tlbl));
}

static void __cpuinit build_r4000_tlb_store_handler(void)
{
        u32 *p = handle_tlbs;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;

        memset(handle_tlbs, 0, sizeof(handle_tlbs));
        memset(labels, 0, sizeof(labels));
        memset(relocs, 0, sizeof(relocs));

        build_r4000_tlbchange_handler_head(&p, &l, &r, K0, K1);
        build_pte_writable(&p, &r, K0, K1, label_nopage_tlbs);
        if (m4kc_tlbp_war())
                build_tlb_probe_entry(&p);
        build_make_write(&p, &r, K0, K1);
        build_r4000_tlbchange_handler_tail(&p, &l, &r, K0, K1);

#ifdef CONFIG_HUGETLB_PAGE
        /*
         * This is the entry point when
         * build_r4000_tlbchange_handler_head spots a huge page.
         */
        uasm_l_tlb_huge_update(&l, p);
        iPTE_LW(&p, K0, K1);
        build_pte_writable(&p, &r, K0, K1, label_nopage_tlbs);
        build_tlb_probe_entry(&p);
        uasm_i_ori(&p, K0, K0,
                   _PAGE_ACCESSED | _PAGE_MODIFIED | _PAGE_VALID | _PAGE_DIRTY);
        build_huge_handler_tail(&p, &r, &l, K0, K1);
#endif

        uasm_l_nopage_tlbs(&l, p);
        uasm_i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);
        uasm_i_nop(&p);

        if ((p - handle_tlbs) > FASTPATH_SIZE)
                panic("TLB store handler fastpath space exceeded");

        uasm_resolve_relocs(relocs, labels);
        pr_debug("Wrote TLB store handler fastpath (%u instructions).\n",
                 (unsigned int)(p - handle_tlbs));

        dump_handler(handle_tlbs, ARRAY_SIZE(handle_tlbs));
}

static void __cpuinit build_r4000_tlb_modify_handler(void)
{
        u32 *p = handle_tlbm;
        struct uasm_label *l = labels;
        struct uasm_reloc *r = relocs;

        memset(handle_tlbm, 0, sizeof(handle_tlbm));
        memset(labels, 0, sizeof(labels));
        memset(relocs, 0, sizeof(relocs));

        build_r4000_tlbchange_handler_head(&p, &l, &r, K0, K1);
        build_pte_modifiable(&p, &r, K0, K1, label_nopage_tlbm);
        if (m4kc_tlbp_war())
                build_tlb_probe_entry(&p);
        /* Present and writable bits set, set accessed and dirty bits. */
        build_make_write(&p, &r, K0, K1);
        build_r4000_tlbchange_handler_tail(&p, &l, &r, K0, K1);

#ifdef CONFIG_HUGETLB_PAGE
        /*
         * This is the entry point when
         * build_r4000_tlbchange_handler_head spots a huge page.
         */
        uasm_l_tlb_huge_update(&l, p);
        iPTE_LW(&p, K0, K1);
        build_pte_modifiable(&p, &r, K0, K1, label_nopage_tlbm);
        build_tlb_probe_entry(&p);
        uasm_i_ori(&p, K0, K0,
                   _PAGE_ACCESSED | _PAGE_MODIFIED | _PAGE_VALID | _PAGE_DIRTY);
        build_huge_handler_tail(&p, &r, &l, K0, K1);
#endif

        uasm_l_nopage_tlbm(&l, p);
        uasm_i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);
        uasm_i_nop(&p);

        if ((p - handle_tlbm) > FASTPATH_SIZE)
                panic("TLB modify handler fastpath space exceeded");

        uasm_resolve_relocs(relocs, labels);
        pr_debug("Wrote TLB modify handler fastpath (%u instructions).\n",
                 (unsigned int)(p - handle_tlbm));

        dump_handler(handle_tlbm, ARRAY_SIZE(handle_tlbm));
}

void __cpuinit build_tlb_refill_handler(void)
{
        /*
         * The refill handler is generated per-CPU, multi-node systems
         * may have local storage for it. The other handlers are only
         * needed once.
         */
        static int run_once = 0;

        switch (current_cpu_type()) {
        case CPU_R2000:
        case CPU_R3000:
        case CPU_R3000A:
        case CPU_R3081E:
        case CPU_TX3912:
        case CPU_TX3922:
        case CPU_TX3927:
                build_r3000_tlb_refill_handler();
                if (!run_once) {
                        build_r3000_tlb_load_handler();
                        build_r3000_tlb_store_handler();
                        build_r3000_tlb_modify_handler();
                        run_once++;
                }
                break;

        case CPU_R6000:
        case CPU_R6000A:
                panic("No R6000 TLB refill handler yet");
                break;

        case CPU_R8000:
                panic("No R8000 TLB refill handler yet");
                break;

        default:
                build_r4000_tlb_refill_handler();
                if (!run_once) {
                        build_r4000_tlb_load_handler();
                        build_r4000_tlb_store_handler();
                        build_r4000_tlb_modify_handler();
                        run_once++;
                }
        }
}

void __cpuinit flush_tlb_handlers(void)
{
        local_flush_icache_range((unsigned long)handle_tlbl,
                           (unsigned long)handle_tlbl + sizeof(handle_tlbl));
        local_flush_icache_range((unsigned long)handle_tlbs,
                           (unsigned long)handle_tlbs + sizeof(handle_tlbs));
        local_flush_icache_range((unsigned long)handle_tlbm,
                           (unsigned long)handle_tlbm + sizeof(handle_tlbm));
}