Archipelago » qemu

/*

 *  MIPS emulation helpers for qemu.

 *

 *  Copyright (c) 2004-2005 Jocelyn Mayer

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with this library; if not, see <http://www.gnu.org/licenses/>.

 */

#include <stdarg.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <inttypes.h>

#include <signal.h>

#include "cpu.h"

#include "exec-all.h"

enum {

    TLBRET_DIRTY = -4,

    TLBRET_INVALID = -3,

    TLBRET_NOMATCH = -2,

    TLBRET_BADADDR = -1,

    TLBRET_MATCH = 0

};

#if !defined(CONFIG_USER_ONLY)

/* no MMU emulation */

int no_mmu_map_address (CPUState *env, target_phys_addr_t *physical, int *prot,

                        target_ulong address, int rw, int access_type)

{

    *physical = address;

    *prot = PAGE_READ | PAGE_WRITE;

    return TLBRET_MATCH;

}

/* fixed mapping MMU emulation */

int fixed_mmu_map_address (CPUState *env, target_phys_addr_t *physical, int *prot,

                           target_ulong address, int rw, int access_type)

{

    if (address <= (int32_t)0x7FFFFFFFUL) {

        if (!(env->CP0_Status & (1 << CP0St_ERL)))

            *physical = address + 0x40000000UL;

        else

            *physical = address;

    } else if (address <= (int32_t)0xBFFFFFFFUL)

        *physical = address & 0x1FFFFFFF;

    else

        *physical = address;

    *prot = PAGE_READ | PAGE_WRITE;

    return TLBRET_MATCH;

}

/* MIPS32/MIPS64 R4000-style MMU emulation */

int r4k_map_address (CPUState *env, target_phys_addr_t *physical, int *prot,

                     target_ulong address, int rw, int access_type)

{

    uint8_t ASID = env->CP0_EntryHi & 0xFF;

    int i;

    for (i = 0; i < env->tlb->tlb_in_use; i++) {

        r4k_tlb_t *tlb = &env->tlb->mmu.r4k.tlb[i];

        /* 1k pages are not supported. */

        target_ulong mask = tlb->PageMask | ~(TARGET_PAGE_MASK << 1);

        target_ulong tag = address & ~mask;

        target_ulong VPN = tlb->VPN & ~mask;

#if defined(TARGET_MIPS64)

        tag &= env->SEGMask;

#endif

        /* Check ASID, virtual page number & size */

        if ((tlb->G == 1 || tlb->ASID == ASID) && VPN == tag) {

            /* TLB match */

            int n = !!(address & mask & ~(mask >> 1));

            /* Check access rights */

            if (!(n ? tlb->V1 : tlb->V0))

                return TLBRET_INVALID;

            if (rw == 0 || (n ? tlb->D1 : tlb->D0)) {

                *physical = tlb->PFN[n] | (address & (mask >> 1));

                *prot = PAGE_READ;

                if (n ? tlb->D1 : tlb->D0)

                    *prot |= PAGE_WRITE;

                return TLBRET_MATCH;

            }

            return TLBRET_DIRTY;

        }

    }

    return TLBRET_NOMATCH;

}

static int get_physical_address (CPUState *env, target_phys_addr_t *physical,

                                int *prot, target_ulong address,

                                int rw, int access_type)

{

    /* User mode can only access useg/xuseg */

    int user_mode = (env->hflags & MIPS_HFLAG_MODE) == MIPS_HFLAG_UM;

    int supervisor_mode = (env->hflags & MIPS_HFLAG_MODE) == MIPS_HFLAG_SM;

    int kernel_mode = !user_mode && !supervisor_mode;

#if defined(TARGET_MIPS64)

    int UX = (env->CP0_Status & (1 << CP0St_UX)) != 0;

    int SX = (env->CP0_Status & (1 << CP0St_SX)) != 0;

    int KX = (env->CP0_Status & (1 << CP0St_KX)) != 0;

#endif

    int ret = TLBRET_MATCH;

#if 0

    qemu_log("user mode %d h %08x\n", user_mode, env->hflags);

#endif

    if (address <= (int32_t)0x7FFFFFFFUL) {

        /* useg */

        if (env->CP0_Status & (1 << CP0St_ERL)) {

            *physical = address & 0xFFFFFFFF;

            *prot = PAGE_READ | PAGE_WRITE;

        } else {

            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);

        }

#if defined(TARGET_MIPS64)

    } else if (address < 0x4000000000000000ULL) {

        /* xuseg */

        if (UX && address <= (0x3FFFFFFFFFFFFFFFULL & env->SEGMask)) {

            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);

        } else {

            ret = TLBRET_BADADDR;

        }

    } else if (address < 0x8000000000000000ULL) {

        /* xsseg */

        if ((supervisor_mode || kernel_mode) &&

            SX && address <= (0x7FFFFFFFFFFFFFFFULL & env->SEGMask)) {

            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);

        } else {

            ret = TLBRET_BADADDR;

        }

    } else if (address < 0xC000000000000000ULL) {

        /* xkphys */

        if (kernel_mode && KX &&

            (address & 0x07FFFFFFFFFFFFFFULL) <= env->PAMask) {

            *physical = address & env->PAMask;

            *prot = PAGE_READ | PAGE_WRITE;

        } else {

            ret = TLBRET_BADADDR;

        }

    } else if (address < 0xFFFFFFFF80000000ULL) {

        /* xkseg */

        if (kernel_mode && KX &&

            address <= (0xFFFFFFFF7FFFFFFFULL & env->SEGMask)) {

            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);

        } else {

            ret = TLBRET_BADADDR;

        }

#endif

    } else if (address < (int32_t)0xA0000000UL) {

        /* kseg0 */

        if (kernel_mode) {

            *physical = address - (int32_t)0x80000000UL;

            *prot = PAGE_READ | PAGE_WRITE;

        } else {

            ret = TLBRET_BADADDR;

        }

    } else if (address < (int32_t)0xC0000000UL) {

        /* kseg1 */

        if (kernel_mode) {

            *physical = address - (int32_t)0xA0000000UL;

            *prot = PAGE_READ | PAGE_WRITE;

        } else {

            ret = TLBRET_BADADDR;

        }

    } else if (address < (int32_t)0xE0000000UL) {

        /* sseg (kseg2) */

        if (supervisor_mode || kernel_mode) {

            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);

        } else {

            ret = TLBRET_BADADDR;

        }

    } else {

        /* kseg3 */

        /* XXX: debug segment is not emulated */

        if (kernel_mode) {

            ret = env->tlb->map_address(env, physical, prot, address, rw, access_type);

        } else {

            ret = TLBRET_BADADDR;

        }

    }

#if 0

    qemu_log(TARGET_FMT_lx " %d %d => " TARGET_FMT_lx " %d (%d)\n",

            address, rw, access_type, *physical, *prot, ret);

#endif

    return ret;

}

#endif

static void raise_mmu_exception(CPUState *env, target_ulong address,

                                int rw, int tlb_error)

{

    int exception = 0, error_code = 0;

    switch (tlb_error) {

    default:

    case TLBRET_BADADDR:

        /* Reference to kernel address from user mode or supervisor mode */

        /* Reference to supervisor address from user mode */

        if (rw)

            exception = EXCP_AdES;

        else

            exception = EXCP_AdEL;

        break;

    case TLBRET_NOMATCH:

        /* No TLB match for a mapped address */

        if (rw)

            exception = EXCP_TLBS;

        else

            exception = EXCP_TLBL;

        error_code = 1;

        break;

    case TLBRET_INVALID:

        /* TLB match with no valid bit */

        if (rw)

            exception = EXCP_TLBS;

        else

            exception = EXCP_TLBL;

        break;

    case TLBRET_DIRTY:

        /* TLB match but 'D' bit is cleared */

        exception = EXCP_LTLBL;

        break;

    }

    /* Raise exception */

    env->CP0_BadVAddr = address;

    env->CP0_Context = (env->CP0_Context & ~0x007fffff) |

                       ((address >> 9) & 0x007ffff0);

    env->CP0_EntryHi =

        (env->CP0_EntryHi & 0xFF) | (address & (TARGET_PAGE_MASK << 1));

#if defined(TARGET_MIPS64)

    env->CP0_EntryHi &= env->SEGMask;

    env->CP0_XContext = (env->CP0_XContext & ((~0ULL) << (env->SEGBITS - 7))) |

                        ((address & 0xC00000000000ULL) >> (55 - env->SEGBITS)) |

                        ((address & ((1ULL << env->SEGBITS) - 1) & 0xFFFFFFFFFFFFE000ULL) >> 9);

#endif

    env->exception_index = exception;

    env->error_code = error_code;

}

#if !defined(CONFIG_USER_ONLY)

target_phys_addr_t cpu_get_phys_page_debug(CPUState *env, target_ulong addr)

{

    target_phys_addr_t phys_addr;

    int prot;

    if (get_physical_address(env, &phys_addr, &prot, addr, 0, ACCESS_INT) != 0)

        return -1;

    return phys_addr;

}

#endif

int cpu_mips_handle_mmu_fault (CPUState *env, target_ulong address, int rw,

                               int mmu_idx, int is_softmmu)

{

#if !defined(CONFIG_USER_ONLY)

    target_phys_addr_t physical;

    int prot;

#endif

    int access_type;

    int ret = 0;

#if 0

    log_cpu_state(env, 0);

#endif

    qemu_log("%s pc " TARGET_FMT_lx " ad " TARGET_FMT_lx " rw %d mmu_idx %d smmu %d\n",

              __func__, env->active_tc.PC, address, rw, mmu_idx, is_softmmu);

    rw &= 1;

    /* data access */

    /* XXX: put correct access by using cpu_restore_state()

       correctly */

    access_type = ACCESS_INT;

#if defined(CONFIG_USER_ONLY)

    ret = TLBRET_NOMATCH;

#else

    ret = get_physical_address(env, &physical, &prot,

                               address, rw, access_type);

    qemu_log("%s address=" TARGET_FMT_lx " ret %d physical " TARGET_FMT_plx " prot %d\n",

              __func__, address, ret, physical, prot);

    if (ret == TLBRET_MATCH) {

       tlb_set_page(env, address & TARGET_PAGE_MASK,

                    physical & TARGET_PAGE_MASK, prot | PAGE_EXEC,

                    mmu_idx, TARGET_PAGE_SIZE);

       ret = 0;

    } else if (ret < 0)

#endif

    {

        raise_mmu_exception(env, address, rw, ret);

        ret = 1;

    }

    return ret;

}

#if !defined(CONFIG_USER_ONLY)

target_phys_addr_t cpu_mips_translate_address(CPUState *env, target_ulong address, int rw)

{

    target_phys_addr_t physical;

    int prot;

    int access_type;

    int ret = 0;

    rw &= 1;

    /* data access */

    access_type = ACCESS_INT;

    ret = get_physical_address(env, &physical, &prot,

                               address, rw, access_type);

    if (ret != TLBRET_MATCH) {

        raise_mmu_exception(env, address, rw, ret);

        return -1LL;

    } else {

        return physical;

    }

}

#endif

static const char * const excp_names[EXCP_LAST + 1] = {

    [EXCP_RESET] = "reset",

    [EXCP_SRESET] = "soft reset",

    [EXCP_DSS] = "debug single step",

    [EXCP_DINT] = "debug interrupt",

    [EXCP_NMI] = "non-maskable interrupt",

    [EXCP_MCHECK] = "machine check",

    [EXCP_EXT_INTERRUPT] = "interrupt",

    [EXCP_DFWATCH] = "deferred watchpoint",

    [EXCP_DIB] = "debug instruction breakpoint",

    [EXCP_IWATCH] = "instruction fetch watchpoint",

    [EXCP_AdEL] = "address error load",

    [EXCP_AdES] = "address error store",

    [EXCP_TLBF] = "TLB refill",

    [EXCP_IBE] = "instruction bus error",

    [EXCP_DBp] = "debug breakpoint",

    [EXCP_SYSCALL] = "syscall",

    [EXCP_BREAK] = "break",

    [EXCP_CpU] = "coprocessor unusable",

    [EXCP_RI] = "reserved instruction",

    [EXCP_OVERFLOW] = "arithmetic overflow",

    [EXCP_TRAP] = "trap",

    [EXCP_FPE] = "floating point",

    [EXCP_DDBS] = "debug data break store",

    [EXCP_DWATCH] = "data watchpoint",

    [EXCP_LTLBL] = "TLB modify",

    [EXCP_TLBL] = "TLB load",

    [EXCP_TLBS] = "TLB store",

    [EXCP_DBE] = "data bus error",

    [EXCP_DDBL] = "debug data break load",

    [EXCP_THREAD] = "thread",

    [EXCP_MDMX] = "MDMX",

    [EXCP_C2E] = "precise coprocessor 2",

    [EXCP_CACHE] = "cache error",

};

#if !defined(CONFIG_USER_ONLY)

static target_ulong exception_resume_pc (CPUState *env)

{

    target_ulong bad_pc;

    target_ulong isa_mode;

    isa_mode = !!(env->hflags & MIPS_HFLAG_M16);

    bad_pc = env->active_tc.PC | isa_mode;

    if (env->hflags & MIPS_HFLAG_BMASK) {

        /* If the exception was raised from a delay slot, come back to

           the jump.  */

        bad_pc -= (env->hflags & MIPS_HFLAG_B16 ? 2 : 4);

    }

    return bad_pc;

}

static void set_hflags_for_handler (CPUState *env)

{

    /* Exception handlers are entered in 32-bit mode.  */

    env->hflags &= ~(MIPS_HFLAG_M16);

    /* ...except that microMIPS lets you choose.  */

    if (env->insn_flags & ASE_MICROMIPS) {

        env->hflags |= (!!(env->CP0_Config3

                           & (1 << CP0C3_ISA_ON_EXC))

                        << MIPS_HFLAG_M16_SHIFT);

    }

}

#endif

void do_interrupt (CPUState *env)

{

#if !defined(CONFIG_USER_ONLY)

    target_ulong offset;

    int cause = -1;

    const char *name;

    if (qemu_log_enabled() && env->exception_index != EXCP_EXT_INTERRUPT) {

        if (env->exception_index < 0 || env->exception_index > EXCP_LAST)

            name = "unknown";

        else

            name = excp_names[env->exception_index];

        qemu_log("%s enter: PC " TARGET_FMT_lx " EPC " TARGET_FMT_lx " %s exception\n",

                 __func__, env->active_tc.PC, env->CP0_EPC, name);

    }

    if (env->exception_index == EXCP_EXT_INTERRUPT &&

        (env->hflags & MIPS_HFLAG_DM))

        env->exception_index = EXCP_DINT;

    offset = 0x180;

    switch (env->exception_index) {

    case EXCP_DSS:

        env->CP0_Debug |= 1 << CP0DB_DSS;

        /* Debug single step cannot be raised inside a delay slot and

           resume will always occur on the next instruction

           (but we assume the pc has always been updated during

           code translation). */

        env->CP0_DEPC = env->active_tc.PC | !!(env->hflags & MIPS_HFLAG_M16);

        goto enter_debug_mode;

    case EXCP_DINT:

        env->CP0_Debug |= 1 << CP0DB_DINT;

        goto set_DEPC;

    case EXCP_DIB:

        env->CP0_Debug |= 1 << CP0DB_DIB;

        goto set_DEPC;

    case EXCP_DBp:

        env->CP0_Debug |= 1 << CP0DB_DBp;

        goto set_DEPC;

    case EXCP_DDBS:

        env->CP0_Debug |= 1 << CP0DB_DDBS;

        goto set_DEPC;

    case EXCP_DDBL:

        env->CP0_Debug |= 1 << CP0DB_DDBL;

    set_DEPC:

        env->CP0_DEPC = exception_resume_pc(env);

        env->hflags &= ~MIPS_HFLAG_BMASK;

 enter_debug_mode:

        env->hflags |= MIPS_HFLAG_DM | MIPS_HFLAG_64 | MIPS_HFLAG_CP0;

        env->hflags &= ~(MIPS_HFLAG_KSU);

        /* EJTAG probe trap enable is not implemented... */

        if (!(env->CP0_Status & (1 << CP0St_EXL)))

            env->CP0_Cause &= ~(1 << CP0Ca_BD);

        env->active_tc.PC = (int32_t)0xBFC00480;

        set_hflags_for_handler(env);

        break;

    case EXCP_RESET:

        cpu_reset(env);

        break;

    case EXCP_SRESET:

        env->CP0_Status |= (1 << CP0St_SR);

        memset(env->CP0_WatchLo, 0, sizeof(*env->CP0_WatchLo));

        goto set_error_EPC;

    case EXCP_NMI:

        env->CP0_Status |= (1 << CP0St_NMI);

 set_error_EPC:

        env->CP0_ErrorEPC = exception_resume_pc(env);

        env->hflags &= ~MIPS_HFLAG_BMASK;

        env->CP0_Status |= (1 << CP0St_ERL) | (1 << CP0St_BEV);

        env->hflags |= MIPS_HFLAG_64 | MIPS_HFLAG_CP0;

        env->hflags &= ~(MIPS_HFLAG_KSU);

        if (!(env->CP0_Status & (1 << CP0St_EXL)))

            env->CP0_Cause &= ~(1 << CP0Ca_BD);

        env->active_tc.PC = (int32_t)0xBFC00000;

        set_hflags_for_handler(env);

        break;

    case EXCP_EXT_INTERRUPT:

        cause = 0;

        if (env->CP0_Cause & (1 << CP0Ca_IV))

            offset = 0x200;

        if (env->CP0_Config3 & ((1 << CP0C3_VInt) | (1 << CP0C3_VEIC))) {

            /* Vectored Interrupts.  */

            unsigned int spacing;

            unsigned int vector;

            unsigned int pending = (env->CP0_Cause & CP0Ca_IP_mask) >> 8;

            /* Compute the Vector Spacing.  */

            spacing = (env->CP0_IntCtl >> CP0IntCtl_VS) & ((1 << 6) - 1);

            spacing <<= 5;

            if (env->CP0_Config3 & (1 << CP0C3_VInt)) {

                /* For VInt mode, the MIPS computes the vector internally.  */

                for (vector = 0; vector < 8; vector++) {

                    if (pending & 1) {

                        /* Found it.  */

                        break;

                    }

                    pending >>= 1;

                }

            } else {

                /* For VEIC mode, the external interrupt controller feeds the

                   vector throught the CP0Cause IP lines.  */

                vector = pending;

            }

            offset = 0x200 + vector * spacing;

        }

        goto set_EPC;

    case EXCP_LTLBL:

        cause = 1;

        goto set_EPC;

    case EXCP_TLBL:

        cause = 2;

        if (env->error_code == 1 && !(env->CP0_Status & (1 << CP0St_EXL))) {

#if defined(TARGET_MIPS64)

            int R = env->CP0_BadVAddr >> 62;

            int UX = (env->CP0_Status & (1 << CP0St_UX)) != 0;

            int SX = (env->CP0_Status & (1 << CP0St_SX)) != 0;

            int KX = (env->CP0_Status & (1 << CP0St_KX)) != 0;

            if (((R == 0 && UX) || (R == 1 && SX) || (R == 3 && KX)) &&

                (!(env->insn_flags & (INSN_LOONGSON2E | INSN_LOONGSON2F))))

                offset = 0x080;

            else

#endif

                offset = 0x000;

        }

        goto set_EPC;

    case EXCP_TLBS:

        cause = 3;

        if (env->error_code == 1 && !(env->CP0_Status & (1 << CP0St_EXL))) {

#if defined(TARGET_MIPS64)

            int R = env->CP0_BadVAddr >> 62;

            int UX = (env->CP0_Status & (1 << CP0St_UX)) != 0;

            int SX = (env->CP0_Status & (1 << CP0St_SX)) != 0;

            int KX = (env->CP0_Status & (1 << CP0St_KX)) != 0;

            if (((R == 0 && UX) || (R == 1 && SX) || (R == 3 && KX)) &&

                (!(env->insn_flags & (INSN_LOONGSON2E | INSN_LOONGSON2F))))

                offset = 0x080;

            else

#endif

                offset = 0x000;

        }

        goto set_EPC;

    case EXCP_AdEL:

        cause = 4;

        goto set_EPC;

    case EXCP_AdES:

        cause = 5;

        goto set_EPC;

    case EXCP_IBE:

        cause = 6;

        goto set_EPC;

    case EXCP_DBE:

        cause = 7;

        goto set_EPC;

    case EXCP_SYSCALL:

        cause = 8;

        goto set_EPC;

    case EXCP_BREAK:

        cause = 9;

        goto set_EPC;

    case EXCP_RI:

        cause = 10;

        goto set_EPC;

    case EXCP_CpU:

        cause = 11;

        env->CP0_Cause = (env->CP0_Cause & ~(0x3 << CP0Ca_CE)) |

                         (env->error_code << CP0Ca_CE);

        goto set_EPC;

    case EXCP_OVERFLOW:

        cause = 12;

        goto set_EPC;

    case EXCP_TRAP:

        cause = 13;

        goto set_EPC;

    case EXCP_FPE:

        cause = 15;

        goto set_EPC;

    case EXCP_C2E:

        cause = 18;

        goto set_EPC;

    case EXCP_MDMX:

        cause = 22;

        goto set_EPC;

    case EXCP_DWATCH:

        cause = 23;

        /* XXX: TODO: manage defered watch exceptions */

        goto set_EPC;

    case EXCP_MCHECK:

        cause = 24;

        goto set_EPC;

    case EXCP_THREAD:

        cause = 25;

        goto set_EPC;

    case EXCP_CACHE:

        cause = 30;

        if (env->CP0_Status & (1 << CP0St_BEV)) {

            offset = 0x100;

        } else {

            offset = 0x20000100;

        }

 set_EPC:

        if (!(env->CP0_Status & (1 << CP0St_EXL))) {

            env->CP0_EPC = exception_resume_pc(env);

            if (env->hflags & MIPS_HFLAG_BMASK) {

                env->CP0_Cause |= (1 << CP0Ca_BD);

            } else {

                env->CP0_Cause &= ~(1 << CP0Ca_BD);

            }

            env->CP0_Status |= (1 << CP0St_EXL);

            env->hflags |= MIPS_HFLAG_64 | MIPS_HFLAG_CP0;

            env->hflags &= ~(MIPS_HFLAG_KSU);

        }

        env->hflags &= ~MIPS_HFLAG_BMASK;

        if (env->CP0_Status & (1 << CP0St_BEV)) {

            env->active_tc.PC = (int32_t)0xBFC00200;

        } else {

            env->active_tc.PC = (int32_t)(env->CP0_EBase & ~0x3ff);

        }

        env->active_tc.PC += offset;

        set_hflags_for_handler(env);

        env->CP0_Cause = (env->CP0_Cause & ~(0x1f << CP0Ca_EC)) | (cause << CP0Ca_EC);

        break;

    default:

        qemu_log("Invalid MIPS exception %d. Exiting\n", env->exception_index);

        printf("Invalid MIPS exception %d. Exiting\n", env->exception_index);

        exit(1);

    }

    if (qemu_log_enabled() && env->exception_index != EXCP_EXT_INTERRUPT) {

        qemu_log("%s: PC " TARGET_FMT_lx " EPC " TARGET_FMT_lx " cause %d\n"

                "    S %08x C %08x A " TARGET_FMT_lx " D " TARGET_FMT_lx "\n",

                __func__, env->active_tc.PC, env->CP0_EPC, cause,

                env->CP0_Status, env->CP0_Cause, env->CP0_BadVAddr,

                env->CP0_DEPC);

    }

#endif

    env->exception_index = EXCP_NONE;

}

#if !defined(CONFIG_USER_ONLY)

void r4k_invalidate_tlb (CPUState *env, int idx, int use_extra)

{

    r4k_tlb_t *tlb;

    target_ulong addr;

    target_ulong end;

    uint8_t ASID = env->CP0_EntryHi & 0xFF;

    target_ulong mask;

    tlb = &env->tlb->mmu.r4k.tlb[idx];

    /* The qemu TLB is flushed when the ASID changes, so no need to

       flush these entries again.  */

    if (tlb->G == 0 && tlb->ASID != ASID) {

        return;

    }

    if (use_extra && env->tlb->tlb_in_use < MIPS_TLB_MAX) {

        /* For tlbwr, we can shadow the discarded entry into

           a new (fake) TLB entry, as long as the guest can not

           tell that it's there.  */

        env->tlb->mmu.r4k.tlb[env->tlb->tlb_in_use] = *tlb;

        env->tlb->tlb_in_use++;

        return;

    }

    /* 1k pages are not supported. */

    mask = tlb->PageMask | ~(TARGET_PAGE_MASK << 1);

    if (tlb->V0) {

        addr = tlb->VPN & ~mask;

#if defined(TARGET_MIPS64)

        if (addr >= (0xFFFFFFFF80000000ULL & env->SEGMask)) {

            addr |= 0x3FFFFF0000000000ULL;

        }

#endif

        end = addr | (mask >> 1);

        while (addr < end) {

            tlb_flush_page (env, addr);

            addr += TARGET_PAGE_SIZE;

        }

    }

    if (tlb->V1) {

        addr = (tlb->VPN & ~mask) | ((mask >> 1) + 1);

#if defined(TARGET_MIPS64)

        if (addr >= (0xFFFFFFFF80000000ULL & env->SEGMask)) {

            addr |= 0x3FFFFF0000000000ULL;

        }

#endif

        end = addr | mask;

        while (addr - 1 < end) {

            tlb_flush_page (env, addr);

            addr += TARGET_PAGE_SIZE;

        }

    }

}

#endif