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  Maciej W. Rozycki
 * Copyright (C) 2006  Ralf Baechle (ralf@linux-mips.org)
 *
 * ... 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/kernel.h>
#include <linux/types.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,
};

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)

/*
 * 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_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 needs this, too.  */
	case CPU_R4600:
	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) {
		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_AU1000:
	case CPU_AU1100:
	case CPU_AU1500:
	case CPU_AU1550:
	case CPU_AU1200:
	case CPU_AU1210:
	case CPU_AU1250:
	case CPU_PR4450:
		uasm_i_nop(p);
		tlbw(p);
		break;

	case CPU_R10000:
	case CPU_R12000:
	case CPU_R14000:
	case CPU_4KC:
	case CPU_SB1:
	case CPU_SB1A:
	case CPU_4KSC:
	case CPU_20KC:
	case CPU_25KF:
	case CPU_BCM3302:
	case CPU_BCM4710:
	case CPU_LOONGSON2:
		if (m4kc_tlbp_war())
			uasm_i_nop(p);
		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_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
}

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

	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_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) > 63)
	    || (((p - tlb_handler) > 61)
		&& uasm_insn_has_bdelay(relocs, tlb_handler + 29)))
		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 + 32;
	if ((p - tlb_handler) <= 32) {
		/* Just copy the handler. */
		uasm_copy_handler(relocs, labels, tlb_handler, p, f);
		final_len = p - tlb_handler;
	} else {
		u32 *split = tlb_handler + 30;

		/*
		 * Find the split point.
		 */
		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;

		/* 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 + 32)) + (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, struct uasm_label **l, 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_label **l, 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, l, 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_label **l, 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, l, 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_label **l, 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, l, 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, &l, &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, &l, &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, &l, &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

	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, l, 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, &l, &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);

	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, &l, &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);

	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, &l, &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);

	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)
{
	flush_icache_range((unsigned long)handle_tlbl,
			   (unsigned long)handle_tlbl + sizeof(handle_tlbl));
	flush_icache_range((unsigned long)handle_tlbs,
			   (unsigned long)handle_tlbs + sizeof(handle_tlbs));
	flush_icache_range((unsigned long)handle_tlbm,
			   (unsigned long)handle_tlbm + sizeof(handle_tlbm));
}