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 <linux/cache.h>

#include <asm/cacheflush.h>
#include <asm/pgtable.h>
#include <asm/war.h>
#include <asm/uasm.h>

/*
 * 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);


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;
}

static int use_bbit_insns(void)
{
	switch (current_cpu_type()) {
	case CPU_CAVIUM_OCTEON:
	case CPU_CAVIUM_OCTEON_PLUS:
	case CPU_CAVIUM_OCTEON2:
		return 1;
	default:
		return 0;
	}
}

static int use_lwx_insns(void)
{
	switch (current_cpu_type()) {
	case CPU_CAVIUM_OCTEON2:
		return 1;
	default:
		return 0;
	}
}
#if defined(CONFIG_CAVIUM_OCTEON_CVMSEG_SIZE) && \
    CONFIG_CAVIUM_OCTEON_CVMSEG_SIZE > 0
static bool scratchpad_available(void)
{
	return true;
}
static int scratchpad_offset(int i)
{
	/*
	 * CVMSEG starts at address -32768 and extends for
	 * CAVIUM_OCTEON_CVMSEG_SIZE 128 byte cache lines.
	 */
	i += 1; /* Kernel use starts at the top and works down. */
	return CONFIG_CAVIUM_OCTEON_CVMSEG_SIZE * 128 - (8 * i) - 32768;
}
#else
static bool scratchpad_available(void)
{
	return false;
}
static int scratchpad_offset(int i)
{
	BUG();
}
#endif
/*
 * 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,
	label_vmalloc,
	label_vmalloc_done,
	label_tlbw_hazard,
	label_split,
	label_tlbl_goaround1,
	label_tlbl_goaround2,
	label_nopage_tlbl,
	label_nopage_tlbs,
	label_nopage_tlbm,
	label_smp_pgtable_change,
	label_r3000_write_probe_fail,
	label_large_segbits_fault,
#ifdef CONFIG_HUGETLB_PAGE
	label_tlb_huge_update,
#endif
};

UASM_L_LA(_second_part)
UASM_L_LA(_leave)
UASM_L_LA(_vmalloc)
UASM_L_LA(_vmalloc_done)
UASM_L_LA(_tlbw_hazard)
UASM_L_LA(_split)
UASM_L_LA(_tlbl_goaround1)
UASM_L_LA(_tlbl_goaround2)
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)
UASM_L_LA(_large_segbits_fault)
#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;

#ifdef CONFIG_64BIT
static int check_for_high_segbits __cpuinitdata;
#endif

static int check_for_high_segbits __cpuinitdata;

static unsigned int kscratch_used_mask __cpuinitdata;

static int __cpuinit allocate_kscratch(void)
{
	int r;
	unsigned int a = cpu_data[0].kscratch_mask & ~kscratch_used_mask;

	r = ffs(a);

	if (r == 0)
		return -1;

	r--; /* make it zero based */

	kscratch_used_mask |= (1 << r);

	return r;
}

static int scratch_reg __cpuinitdata;
static int pgd_reg __cpuinitdata;
enum vmalloc64_mode {not_refill, refill_scratch, refill_noscratch};

#ifndef CONFIG_MIPS_PGD_C0_CONTEXT

/*
 * CONFIG_MIPS_PGD_C0_CONTEXT implies 64 bit and lack of pgd_current,
 * we cannot do r3000 under these circumstances.
 *
 * Declare pgd_current here instead of including mmu_context.h to avoid type
 * conflicts for tlbmiss_handler_setup_pgd
 */
extern unsigned long pgd_current[];

/*
 * 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);
}
#endif /* CONFIG_MIPS_PGD_C0_CONTEXT */

/*
 * 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_BMIPS32:
	case CPU_BMIPS3300:
	case CPU_BMIPS4350:
	case CPU_BMIPS4380:
	case CPU_BMIPS5000:
	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;

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

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

static __cpuinit __maybe_unused void build_convert_pte_to_entrylo(u32 **p,
								  unsigned int reg)
{
	if (kernel_uses_smartmips_rixi) {
		UASM_i_SRL(p, reg, reg, ilog2(_PAGE_NO_EXEC));
		UASM_i_ROTR(p, reg, reg, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
	} else {
#ifdef CONFIG_64BIT_PHYS_ADDR
		uasm_i_dsrl_safe(p, reg, reg, ilog2(_PAGE_GLOBAL));
#else
		UASM_i_SRL(p, reg, reg, ilog2(_PAGE_GLOBAL));
#endif
	}
}

#ifdef CONFIG_HUGETLB_PAGE

static __cpuinit void build_restore_pagemask(u32 **p,
					     struct uasm_reloc **r,
					     unsigned int tmp,
					     enum label_id lid,
					     int restore_scratch)
{
	if (restore_scratch) {
		/* 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_i_mtc0(p, tmp, C0_PAGEMASK);
			uasm_il_b(p, r, lid);
		} else if (PM_DEFAULT_MASK) {
			uasm_i_ori(p, tmp, 0, PM_DEFAULT_MASK);
			uasm_i_mtc0(p, tmp, C0_PAGEMASK);
			uasm_il_b(p, r, lid);
		} else {
			uasm_i_mtc0(p, 0, C0_PAGEMASK);
			uasm_il_b(p, r, lid);
		}
		if (scratch_reg > 0)
			UASM_i_MFC0(p, 1, 31, scratch_reg);
		else
			UASM_i_LW(p, 1, scratchpad_offset(0), 0);
	} else {
		/* 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, lid);
			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, lid);
			uasm_i_mtc0(p, tmp, C0_PAGEMASK);
		} else {
			uasm_il_b(p, r, lid);
			uasm_i_mtc0(p, 0, C0_PAGEMASK);
		}
	}
}

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,
						 int restore_scratch)
{
	/* 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);

	build_restore_pagemask(p, r, tmp, label_leave, restore_scratch);
}

/*
 * 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);
	if (use_bbit_insns()) {
		uasm_il_bbit1(p, r, tmp, ilog2(_PAGE_HUGE), lid);
	} else {
		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));

	build_convert_pte_to_entrylo(p, pte);
	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, 0);
}
#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)
{
#ifndef CONFIG_MIPS_PGD_C0_CONTEXT
	long pgdc = (long)pgd_current;
#endif
	/*
	 * The vmalloc handling is not in the hotpath.
	 */
	uasm_i_dmfc0(p, tmp, C0_BADVADDR);

	if (check_for_high_segbits) {
		/*
		 * The kernel currently implicitely assumes that the
		 * MIPS SEGBITS parameter for the processor is
		 * (PGDIR_SHIFT+PGDIR_BITS) or less, and will never
		 * allocate virtual addresses outside the maximum
		 * range for SEGBITS = (PGDIR_SHIFT+PGDIR_BITS). But
		 * that doesn't prevent user code from accessing the
		 * higher xuseg addresses.  Here, we make sure that
		 * everything but the lower xuseg addresses goes down
		 * the module_alloc/vmalloc path.
		 */
		uasm_i_dsrl_safe(p, ptr, tmp, PGDIR_SHIFT + PGD_ORDER + PAGE_SHIFT - 3);
		uasm_il_bnez(p, r, ptr, label_vmalloc);
	} else {
		uasm_il_bltz(p, r, tmp, label_vmalloc);
	}
	/* No uasm_i_nop needed here, since the next insn doesn't touch TMP. */

#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
	if (pgd_reg != -1) {
		/* pgd is in pgd_reg */
		UASM_i_MFC0(p, ptr, 31, pgd_reg);
	} else {
		/*
		 * &pgd << 11 stored in CONTEXT [23..63].
		 */
		UASM_i_MFC0(p, ptr, C0_CONTEXT);

		/* Clear lower 23 bits of context. */
		uasm_i_dins(p, ptr, 0, 0, 23);

		/* 1 0  1 0 1  << 6  xkphys cached */
		uasm_i_ori(p, ptr, ptr, 0x540);
		uasm_i_drotr(p, ptr, ptr, 11);
	}
#elif defined(CONFIG_SMP)
# ifdef  CONFIG_MIPS_MT_SMTC
	/*
	 * SMTC uses TCBind value as "CPU" index
	 */
	uasm_i_mfc0(p, ptr, C0_TCBIND);
	uasm_i_dsrl_safe(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_safe(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);

	/* get pgd offset in bytes */
	uasm_i_dsrl_safe(p, tmp, tmp, PGDIR_SHIFT - 3);

	uasm_i_andi(p, tmp, tmp, (PTRS_PER_PGD - 1)<<3);
	uasm_i_daddu(p, ptr, ptr, tmp); /* add in pgd offset */
#ifndef __PAGETABLE_PMD_FOLDED
	uasm_i_dmfc0(p, tmp, C0_BADVADDR); /* get faulting address */
	uasm_i_ld(p, ptr, 0, ptr); /* get pmd pointer */
	uasm_i_dsrl_safe(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 */
#endif
}

/*
 * 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,
			enum vmalloc64_mode mode)
{
	long swpd = (long)swapper_pg_dir;
	int single_insn_swpd;
	int did_vmalloc_branch = 0;

	single_insn_swpd = uasm_in_compat_space_p(swpd) && !uasm_rel_lo(swpd);

	uasm_l_vmalloc(l, *p);

	if (mode != not_refill && check_for_high_segbits) {
		if (single_insn_swpd) {
			uasm_il_bltz(p, r, bvaddr, label_vmalloc_done);
			uasm_i_lui(p, ptr, uasm_rel_hi(swpd));
			did_vmalloc_branch = 1;
			/* fall through */
		} else {
			uasm_il_bgez(p, r, bvaddr, label_large_segbits_fault);
		}
	}
	if (!did_vmalloc_branch) {
		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));
		}
	}
	if (mode != not_refill && check_for_high_segbits) {
		uasm_l_large_segbits_fault(l, *p);
		/*
		 * We get here if we are an xsseg address, or if we are
		 * an xuseg address above (PGDIR_SHIFT+PGDIR_BITS) boundary.
		 *
		 * Ignoring xsseg (assume disabled so would generate
		 * (address errors?), the only remaining possibility
		 * is the upper xuseg addresses.  On processors with
		 * TLB_SEGBITS <= PGDIR_SHIFT+PGDIR_BITS, these
		 * addresses would have taken an address error. We try
		 * to mimic that here by taking a load/istream page
		 * fault.
		 */
		UASM_i_LA(p, ptr, (unsigned long)tlb_do_page_fault_0);
		uasm_i_jr(p, ptr);

		if (mode == refill_scratch) {
			if (scratch_reg > 0)
				UASM_i_MFC0(p, 1, 31, scratch_reg);
			else
				UASM_i_LW(p, 1, scratchpad_offset(0), 0);
		} else {
			uasm_i_nop(p);
		}
	}
}

#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 */
		if (kernel_uses_smartmips_rixi) {
			UASM_i_SRL(p, tmp, tmp, ilog2(_PAGE_NO_EXEC));
			UASM_i_SRL(p, ptep, ptep, ilog2(_PAGE_NO_EXEC));
			UASM_i_ROTR(p, tmp, tmp, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
			UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
			UASM_i_ROTR(p, ptep, ptep, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
		} else {
			uasm_i_dsrl_safe(p, tmp, tmp, ilog2(_PAGE_GLOBAL)); /* convert to entrylo0 */
			UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
			uasm_i_dsrl_safe(p, ptep, ptep, ilog2(_PAGE_GLOBAL)); /* 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);
	if (kernel_uses_smartmips_rixi) {
		UASM_i_SRL(p, tmp, tmp, ilog2(_PAGE_NO_EXEC));
		UASM_i_SRL(p, ptep, ptep, ilog2(_PAGE_NO_EXEC));
		UASM_i_ROTR(p, tmp, tmp, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
		if (r4k_250MHZhwbug())
			UASM_i_MTC0(p, 0, C0_ENTRYLO0);
		UASM_i_MTC0(p, tmp, C0_ENTRYLO0); /* load it */
		UASM_i_ROTR(p, ptep, ptep, ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
	} else {
		UASM_i_SRL(p, tmp, tmp, ilog2(_PAGE_GLOBAL)); /* 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, ilog2(_PAGE_GLOBAL)); /* 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
}

struct mips_huge_tlb_info {
	int huge_pte;
	int restore_scratch;
};

static struct mips_huge_tlb_info __cpuinit
build_fast_tlb_refill_handler (u32 **p, struct uasm_label **l,
			       struct uasm_reloc **r, unsigned int tmp,
			       unsigned int ptr, int c0_scratch)
{
	struct mips_huge_tlb_info rv;
	unsigned int even, odd;
	int vmalloc_branch_delay_filled = 0;
	const int scratch = 1; /* Our extra working register */

	rv.huge_pte = scratch;
	rv.restore_scratch = 0;

	if (check_for_high_segbits) {
		UASM_i_MFC0(p, tmp, C0_BADVADDR);

		if (pgd_reg != -1)
			UASM_i_MFC0(p, ptr, 31, pgd_reg);
		else
			UASM_i_MFC0(p, ptr, C0_CONTEXT);

		if (c0_scratch >= 0)
			UASM_i_MTC0(p, scratch, 31, c0_scratch);
		else
			UASM_i_SW(p, scratch, scratchpad_offset(0), 0);

		uasm_i_dsrl_safe(p, scratch, tmp,
				 PGDIR_SHIFT + PGD_ORDER + PAGE_SHIFT - 3);
		uasm_il_bnez(p, r, scratch, label_vmalloc);

		if (pgd_reg == -1) {
			vmalloc_branch_delay_filled = 1;
			/* Clear lower 23 bits of context. */
			uasm_i_dins(p, ptr, 0, 0, 23);
		}
	} else {
		if (pgd_reg != -1)
			UASM_i_MFC0(p, ptr, 31, pgd_reg);
		else
			UASM_i_MFC0(p, ptr, C0_CONTEXT);

		UASM_i_MFC0(p, tmp, C0_BADVADDR);

		if (c0_scratch >= 0)
			UASM_i_MTC0(p, scratch, 31, c0_scratch);
		else
			UASM_i_SW(p, scratch, scratchpad_offset(0), 0);

		if (pgd_reg == -1)
			/* Clear lower 23 bits of context. */
			uasm_i_dins(p, ptr, 0, 0, 23);

		uasm_il_bltz(p, r, tmp, label_vmalloc);
	}

	if (pgd_reg == -1) {
		vmalloc_branch_delay_filled = 1;
		/* 1 0  1 0 1  << 6  xkphys cached */
		uasm_i_ori(p, ptr, ptr, 0x540);
		uasm_i_drotr(p, ptr, ptr, 11);
	}

#ifdef __PAGETABLE_PMD_FOLDED
#define LOC_PTEP scratch
#else
#define LOC_PTEP ptr
#endif

	if (!vmalloc_branch_delay_filled)
		/* get pgd offset in bytes */
		uasm_i_dsrl_safe(p, scratch, tmp, PGDIR_SHIFT - 3);

	uasm_l_vmalloc_done(l, *p);

	/*
	 *                         tmp          ptr
	 * fall-through case =   badvaddr  *pgd_current
	 * vmalloc case      =   badvaddr  swapper_pg_dir
	 */

	if (vmalloc_branch_delay_filled)
		/* get pgd offset in bytes */
		uasm_i_dsrl_safe(p, scratch, tmp, PGDIR_SHIFT - 3);

#ifdef __PAGETABLE_PMD_FOLDED
	GET_CONTEXT(p, tmp); /* get context reg */
#endif
	uasm_i_andi(p, scratch, scratch, (PTRS_PER_PGD - 1) << 3);

	if (use_lwx_insns()) {
		UASM_i_LWX(p, LOC_PTEP, scratch, ptr);
	} else {
		uasm_i_daddu(p, ptr, ptr, scratch); /* add in pgd offset */
		uasm_i_ld(p, LOC_PTEP, 0, ptr); /* get pmd pointer */
	}

#ifndef __PAGETABLE_PMD_FOLDED
	/* get pmd offset in bytes */
	uasm_i_dsrl_safe(p, scratch, tmp, PMD_SHIFT - 3);
	uasm_i_andi(p, scratch, scratch, (PTRS_PER_PMD - 1) << 3);
	GET_CONTEXT(p, tmp); /* get context reg */

	if (use_lwx_insns()) {
		UASM_i_LWX(p, scratch, scratch, ptr);
	} else {
		uasm_i_daddu(p, ptr, ptr, scratch); /* add in pmd offset */
		UASM_i_LW(p, scratch, 0, ptr);
	}
#endif
	/* Adjust the context during the load latency. */
	build_adjust_context(p, tmp);

#ifdef CONFIG_HUGETLB_PAGE
	uasm_il_bbit1(p, r, scratch, ilog2(_PAGE_HUGE), label_tlb_huge_update);
	/*
	 * The in the LWX case we don't want to do the load in the
	 * delay slot.  It cannot issue in the same cycle and may be
	 * speculative and unneeded.
	 */
	if (use_lwx_insns())
		uasm_i_nop(p);
#endif /* CONFIG_HUGETLB_PAGE */


	/* build_update_entries */
	if (use_lwx_insns()) {
		even = ptr;
		odd = tmp;
		UASM_i_LWX(p, even, scratch, tmp);
		UASM_i_ADDIU(p, tmp, tmp, sizeof(pte_t));
		UASM_i_LWX(p, odd, scratch, tmp);
	} else {
		UASM_i_ADDU(p, ptr, scratch, tmp); /* add in offset */
		even = tmp;
		odd = ptr;
		UASM_i_LW(p, even, 0, ptr); /* get even pte */
		UASM_i_LW(p, odd, sizeof(pte_t), ptr); /* get odd pte */
	}
	if (kernel_uses_smartmips_rixi) {
		uasm_i_dsrl_safe(p, even, even, ilog2(_PAGE_NO_EXEC));
		uasm_i_dsrl_safe(p, odd, odd, ilog2(_PAGE_NO_EXEC));
		uasm_i_drotr(p, even, even,
			     ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
		UASM_i_MTC0(p, even, C0_ENTRYLO0); /* load it */
		uasm_i_drotr(p, odd, odd,
			     ilog2(_PAGE_GLOBAL) - ilog2(_PAGE_NO_EXEC));
	} else {
		uasm_i_dsrl_safe(p, even, even, ilog2(_PAGE_GLOBAL));
		UASM_i_MTC0(p, even, C0_ENTRYLO0); /* load it */
		uasm_i_dsrl_safe(p, odd, odd, ilog2(_PAGE_GLOBAL));
	}
	UASM_i_MTC0(p, odd, C0_ENTRYLO1); /* load it */

	if (c0_scratch >= 0) {
		UASM_i_MFC0(p, scratch, 31, c0_scratch);
		build_tlb_write_entry(p, l, r, tlb_random);
		uasm_l_leave(l, *p);
		rv.restore_scratch = 1;
	} else if (PAGE_SHIFT == 14 || PAGE_SHIFT == 13)  {
		build_tlb_write_entry(p, l, r, tlb_random);
		uasm_l_leave(l, *p);
		UASM_i_LW(p, scratch, scratchpad_offset(0), 0);
	} else {
		UASM_i_LW(p, scratch, scratchpad_offset(0), 0);
		build_tlb_write_entry(p, l, r, tlb_random);
		uasm_l_leave(l, *p);
		rv.restore_scratch = 1;
	}

	uasm_i_eret(p); /* return from trap */

	return rv;
}

/*
 * 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;
	struct mips_huge_tlb_info htlb_info;
	enum vmalloc64_mode vmalloc_mode;

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

	if (scratch_reg == 0)
		scratch_reg = allocate_kscratch();

	if ((scratch_reg > 0 || scratchpad_available()) && use_bbit_insns()) {
		htlb_info = build_fast_tlb_refill_handler(&p, &l, &r, K0, K1,
							  scratch_reg);
		vmalloc_mode = refill_scratch;
	} else {
		htlb_info.huge_pte = K0;
		htlb_info.restore_scratch = 0;
		vmalloc_mode = refill_noscratch;
		/*
		 * create the plain linear handler
		 */
		if (bcm1250_m3_war()) {
			unsigned int segbits = 44;

			uasm_i_dmfc0(&p, K0, C0_BADVADDR);
			uasm_i_dmfc0(&p, K1, C0_ENTRYHI);
			uasm_i_xor(&p, K0, K0, K1);
			uasm_i_dsrl_safe(&p, K1, K0, 62);
			uasm_i_dsrl_safe(&p, K0, K0, 12 + 1);
			uasm_i_dsll_safe(&p, K0, K0, 64 + 12 + 1 - segbits);
			uasm_i_or(&p, K0, K0, K1);
			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);
	build_huge_update_entries(&p, htlb_info.huge_pte, K1);
	build_huge_tlb_write_entry(&p, &l, &r, K0, tlb_random,
				   htlb_info.restore_scratch);
#endif

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

/*
 * 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;
#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
u32 tlbmiss_handler_setup_pgd[16] __cacheline_aligned;

static void __cpuinit build_r4000_setup_pgd(void)
{
	const int a0 = 4;
	const int a1 = 5;
	u32 *p = tlbmiss_handler_setup_pgd;
	struct uasm_label *l = labels;
	struct uasm_reloc *r = relocs;

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

	pgd_reg = allocate_kscratch();

	if (pgd_reg == -1) {
		/* PGD << 11 in c0_Context */
		/*
		 * If it is a ckseg0 address, convert to a physical
		 * address.  Shifting right by 29 and adding 4 will
		 * result in zero for these addresses.
		 *
		 */
		UASM_i_SRA(&p, a1, a0, 29);
		UASM_i_ADDIU(&p, a1, a1, 4);
		uasm_il_bnez(&p, &r, a1, label_tlbl_goaround1);
		uasm_i_nop(&p);
		uasm_i_dinsm(&p, a0, 0, 29, 64 - 29);
		uasm_l_tlbl_goaround1(&l, p);
		UASM_i_SLL(&p, a0, a0, 11);
		uasm_i_jr(&p, 31);
		UASM_i_MTC0(&p, a0, C0_CONTEXT);
	} else {
		/* PGD in c0_KScratch */
		uasm_i_jr(&p, 31);
		UASM_i_MTC0(&p, a0, 31, pgd_reg);
	}
	if (p - tlbmiss_handler_setup_pgd > ARRAY_SIZE(tlbmiss_handler_setup_pgd))
		panic("tlbmiss_handler_setup_pgd space exceeded");
	uasm_resolve_relocs(relocs, labels);
	pr_debug("Wrote tlbmiss_handler_setup_pgd (%u instructions).\n",
		 (unsigned int)(p - tlbmiss_handler_setup_pgd));

	dump_handler(tlbmiss_handler_setup_pgd,
		     ARRAY_SIZE(tlbmiss_handler_setup_pgd));
}
#endif

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)
{
	if (kernel_uses_smartmips_rixi) {
		if (use_bbit_insns()) {
			uasm_il_bbit0(p, r, pte, ilog2(_PAGE_PRESENT), lid);
			uasm_i_nop(p);
		} else {
			uasm_i_andi(p, pte, pte, _PAGE_PRESENT);
			uasm_il_beqz(p, r, pte, lid);
			iPTE_LW(p, pte, ptr);
		}
	} else {
		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)
{
	if (use_bbit_insns()) {
		uasm_il_bbit0(p, r, pte, ilog2(_PAGE_PRESENT), lid);
		uasm_i_nop(p);
		uasm_il_bbit0(p, r, pte, ilog2(_PAGE_WRITE), lid);
		uasm_i_nop(p);
	} else {
		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)
{
	if (use_bbit_insns()) {
		uasm_il_bbit0(p, r, pte, ilog2(_PAGE_WRITE), lid);
		uasm_i_nop(p);
	} else {
		uasm_i_andi(p, pte, pte, _PAGE_WRITE);
		uasm_il_beqz(p, r, pte, lid);
		iPTE_LW(p, pte, ptr);
	}
}

#ifndef CONFIG_MIPS_PGD_C0_CONTEXT


/*
 * 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));
}
#endif /* CONFIG_MIPS_PGD_C0_CONTEXT */

/*
 * 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, not_refill);
#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()) {
		unsigned int segbits = 44;

		uasm_i_dmfc0(&p, K0, C0_BADVADDR);
		uasm_i_dmfc0(&p, K1, C0_ENTRYHI);
		uasm_i_xor(&p, K0, K0, K1);
		uasm_i_dsrl_safe(&p, K1, K0, 62);
		uasm_i_dsrl_safe(&p, K0, K0, 12 + 1);
		uasm_i_dsll_safe(&p, K0, K0, 64 + 12 + 1 - segbits);
		uasm_i_or(&p, K0, K0, K1);
		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);

	if (kernel_uses_smartmips_rixi) {
		/*
		 * If the page is not _PAGE_VALID, RI or XI could not
		 * have triggered it.  Skip the expensive test..
		 */
		if (use_bbit_insns()) {
			uasm_il_bbit0(&p, &r, K0, ilog2(_PAGE_VALID),
				      label_tlbl_goaround1);
		} else {
			uasm_i_andi(&p, K0, K0, _PAGE_VALID);
			uasm_il_beqz(&p, &r, K0, label_tlbl_goaround1);
		}
		uasm_i_nop(&p);

		uasm_i_tlbr(&p);
		/* Examine  entrylo 0 or 1 based on ptr. */
		if (use_bbit_insns()) {
			uasm_i_bbit0(&p, K1, ilog2(sizeof(pte_t)), 8);
		} else {
			uasm_i_andi(&p, K0, K1, sizeof(pte_t));
			uasm_i_beqz(&p, K0, 8);
		}

		UASM_i_MFC0(&p, K0, C0_ENTRYLO0); /* load it in the delay slot*/
		UASM_i_MFC0(&p, K0, C0_ENTRYLO1); /* load it if ptr is odd */
		/*
		 * If the entryLo (now in K0) is valid (bit 1), RI or
		 * XI must have triggered it.
		 */
		if (use_bbit_insns()) {
			uasm_il_bbit1(&p, &r, K0, 1, label_nopage_tlbl);
			/* Reload the PTE value */
			iPTE_LW(&p, K0, K1);
			uasm_l_tlbl_goaround1(&l, p);
		} else {
			uasm_i_andi(&p, K0, K0, 2);
			uasm_il_bnez(&p, &r, K0, label_nopage_tlbl);
			uasm_l_tlbl_goaround1(&l, p);
			/* Reload the PTE value */
			iPTE_LW(&p, K0, K1);
		}
	}
	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);

	if (kernel_uses_smartmips_rixi) {
		/*
		 * If the page is not _PAGE_VALID, RI or XI could not
		 * have triggered it.  Skip the expensive test..
		 */
		if (use_bbit_insns()) {
			uasm_il_bbit0(&p, &r, K0, ilog2(_PAGE_VALID),
				      label_tlbl_goaround2);
		} else {
			uasm_i_andi(&p, K0, K0, _PAGE_VALID);
			uasm_il_beqz(&p, &r, K0, label_tlbl_goaround2);
		}
		uasm_i_nop(&p);

		uasm_i_tlbr(&p);
		/* Examine  entrylo 0 or 1 based on ptr. */
		if (use_bbit_insns()) {
			uasm_i_bbit0(&p, K1, ilog2(sizeof(pte_t)), 8);
		} else {
			uasm_i_andi(&p, K0, K1, sizeof(pte_t));
			uasm_i_beqz(&p, K0, 8);
		}
		UASM_i_MFC0(&p, K0, C0_ENTRYLO0); /* load it in the delay slot*/
		UASM_i_MFC0(&p, K0, C0_ENTRYLO1); /* load it if ptr is odd */
		/*
		 * If the entryLo (now in K0) is valid (bit 1), RI or
		 * XI must have triggered it.
		 */
		if (use_bbit_insns()) {
			uasm_il_bbit0(&p, &r, K0, 1, label_tlbl_goaround2);
		} else {
			uasm_i_andi(&p, K0, K0, 2);
			uasm_il_beqz(&p, &r, K0, label_tlbl_goaround2);
		}
		/* Reload the PTE value */
		iPTE_LW(&p, K0, K1);

		/*
		 * We clobbered C0_PAGEMASK, restore it.  On the other branch
		 * it is restored in build_huge_tlb_write_entry.
		 */
		build_restore_pagemask(&p, &r, K0, label_nopage_tlbl, 0);

		uasm_l_tlbl_goaround2(&l, 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;

#ifdef CONFIG_64BIT
	check_for_high_segbits = current_cpu_data.vmbits > (PGDIR_SHIFT + PGD_ORDER + PAGE_SHIFT - 3);
#endif

	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:
#ifndef CONFIG_MIPS_PGD_C0_CONTEXT
		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++;
		}
#else
		panic("No R3000 TLB refill handler");
#endif
		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:
		if (!run_once) {
#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
			build_r4000_setup_pgd();
#endif
			build_r4000_tlb_load_handler();
			build_r4000_tlb_store_handler();
			build_r4000_tlb_modify_handler();
			run_once++;
		}
		build_r4000_tlb_refill_handler();
	}
}

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));
#ifdef CONFIG_MIPS_PGD_C0_CONTEXT
	local_flush_icache_range((unsigned long)tlbmiss_handler_setup_pgd,
			   (unsigned long)tlbmiss_handler_setup_pgd + sizeof(handle_tlbm));
#endif
}