src/cpus/bintrans.c

/*
 *  Copyright (C) 2004-2005  Anders Gavare.  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright  
 *     notice, this list of conditions and the following disclaimer in the 
 *     documentation and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 *  ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 *  ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE   
 *  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 *  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 *  OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 *  HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 *  LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 *  OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *
 *
 *  $Id: bintrans.c,v 1.4 2005/12/26 12:32:10 debug Exp $
 *
 *  Dynamic binary translation.
 *
 *
 *  --------------------------------------------------------------------------
 *
 *    NOTE: This code needs a lot of updating; much of it is MIPS-specific.
 *
 *  --------------------------------------------------------------------------
 *
 *
 *  This should be documented/commented better. Some of the main concepts are:
 *
 *      o)  Keep a translation cache of a certain number of blocks.
 *
 *      o)  Only translate simple instructions. (For example, the 'tlbwr'
 *          instruction is not actually translated, converted into a call
 *          to C code.)
 *
 *      o)  Translate code in physical ram, not virtual. This will keep
 *          things translated over process switches, and TLB updates.
 *
 *      o)  When the translation cache is "full", then throw away everything
 *          translated so far and restart from scratch. The cache is of a
 *          fixed size, say 24 MB. (This is inspired by a comment in the Qemu
 *          technical documentation: "A 16 MByte cache holds the most recently
 *          used translations. For simplicity, it is completely flushed when
 *          it is full.")
 *
 *      o)  Do not translate over MIPS page boundaries (4 KB).
 *          (TODO: Perhaps it would be possible if we're running in kernel
 *          space? But that would require special checks at the end of
 *          each page.)
 *
 *      o)  If memory is overwritten, any translated block for that page
 *          must be invalidated. (It is removed from the cache so that it
 *          cannot be found on lookups.)
 *
 *      o)  Only run a certain number of instructions, before returning to
 *          the main loop. (This is needed in order to allow devices to
 *          cause interrupts, and so on.)
 *
 *      o)  Check for exceptions inside the block, for those instructions
 *          that require that.  Update the program counter by the number
 *          of successfully executed instructions only.
 *
 *      o)  There is no "intermediate representation"; everything is translated
 *          directly from MIPS machine code to target machine code.
 *
 *      o)  Theoretical support for multiple target architectures (Alpha,
 *          i386, sparc, mips :-), ...), but only Alpha and i386 implemented
 *          so far.
 *
 *      o)  Load/stores: TODO: Comment.
 *
 *
 *  The general idea is something like this:
 *
 *      Check for the current PC (actually: its physical form) in the
 *      translation cache. If it is found, then run the translated code chunk,
 *      otherwise try to translate and then run it.
 *
 *  A few checks are made though, to make sure that the environment is "safe"
 *  enough; starting inside a delay slot or "nullified" slot is considered
 *  non-safe.
 */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/mman.h>

#include "bintrans.h"
#include "cop0.h"
#include "cpu.h"
#include "cpu_mips.h"
#include "machine.h"
#include "memory.h"
#include "mips_cpu_types.h"
#include "misc.h"
#include "opcodes_mips.h"


#ifndef BINTRANS

/*
 *  No bintrans, then let's supply dummy functions:
 */

int bintrans_pc_is_in_cache(struct cpu *cpu, uint64_t pc) { return 0; }
void bintrans_invalidate(struct cpu *cpu, uint64_t paddr) { }
int bintrans_attempt_translate(struct cpu *cpu, uint64_t paddr) { return 0; }
void bintrans_restart(struct cpu *cpu) { }
void bintrans_init_cpu(struct cpu *cpu) { }
void bintrans_init(struct machine *machine, struct memory *mem)
{
        fatal("\n***  NOT starting bintrans, as gxemul "
            "was compiled without such support!\n\n");
}

#else


/*  Function declaration, should be the same as in bintrans_*.c:  */

static void bintrans_host_cacheinvalidate(unsigned char *p, size_t len);
static void bintrans_write_chunkreturn(unsigned char **addrp);
static void bintrans_write_chunkreturn_fail(unsigned char **addrp);
static void bintrans_write_pc_inc(unsigned char **addrp);
static void bintrans_write_quickjump(struct memory *mem,
        unsigned char *quickjump_code, uint32_t chunkoffset);
static int bintrans_write_instruction__addiu_etc(struct memory *mem,
        unsigned char **addrp, int rt, int rs, int imm,
        int instruction_type);
static int bintrans_write_instruction__addu_etc(struct memory *mem,
        unsigned char **addrp, int rd, int rs, int rt, int sa,
        int instruction_type);
static int bintrans_write_instruction__branch(unsigned char **addrp,
        int instruction_type, int regimm_type, int rt, int rs, int imm);
static int bintrans_write_instruction__jr(unsigned char **addrp, int rs,
        int rd, int special);
static int bintrans_write_instruction__jal(unsigned char **addrp, int imm,
        int link);
static int bintrans_write_instruction__delayedbranch(struct memory *mem,
        unsigned char **addrp, uint32_t *potential_chunk_p, uint32_t *chunks,
        int only_care_about_chunk_p, int p, int forward);
static int bintrans_write_instruction__loadstore(struct memory *mem,
        unsigned char **addrp, int rt, int imm, int rs, int instruction_type,
        int bigendian, int do_alignment_check);
static int bintrans_write_instruction__lui(unsigned char **addrp, int rt,
        int imm);
static int bintrans_write_instruction__mfmthilo(unsigned char **addrp, int rd,
        int from_flag, int hi_flag);
static int bintrans_write_instruction__mfc_mtc(struct memory *mem,
        unsigned char **addrp, int coproc_nr, int flag64bit, int rt, int rd,
        int mtcflag);
static int bintrans_write_instruction__tlb_rfe_etc(unsigned char **addrp,
        int itype);

#define CALL_TLBWI      0
#define CALL_TLBWR      1
#define CALL_TLBP       2
#define CALL_TLBR       3
#define CALL_RFE        4
#define CALL_ERET       5
#define CALL_BREAK      6
#define CALL_SYSCALL    7


static void bintrans_register_potential_quick_jump(struct memory *mem,
        unsigned char *a, int p)
{
        /*  printf("%02i: a=%016llx p=%i\n", mem->quick_jumps_index, a, p);  */
        mem->quick_jump_host_address[mem->quick_jumps_index] = a;
        mem->quick_jump_page_offset[mem->quick_jumps_index] = p;
        mem->quick_jumps_index ++;
        if (mem->quick_jumps_index > mem->n_quick_jumps)
                mem->n_quick_jumps = mem->quick_jumps_index;
        if (mem->quick_jumps_index >= MAX_QUICK_JUMPS)
                mem->quick_jumps_index = 0;
}


/*  Include host architecture specific bintrans code:  */

#ifdef ALPHA
#define BACKEND_NAME "Alpha"
#include "bintrans_alpha.c"
#else
#ifdef I386
#define BACKEND_NAME "i386"
#include "bintrans_i386.c"
#else
#error Unsupported host architecture for bintrans.
#endif  /*  I386  */
#endif  /*  ALPHA  */


/*
 *  old_bintrans_invalidate():
 *
 *  Invalidate translations containing a certain physical address.
 */
static void old_bintrans_invalidate(struct cpu *cpu, uint64_t paddr)
{
        int entry_index = PADDR_TO_INDEX(paddr);
        struct translation_page_entry *tep;
#if 0
struct translation_page_entry *prev = NULL;
#endif
        uint64_t paddr_page = paddr & ~0xfff;

        tep = cpu->mem->translation_page_entry_array[entry_index];
        while (tep != NULL) {
                if (tep->paddr == paddr_page)
#if 1
                        break;
#else
{
                        if (prev == NULL)
                                cpu->mem->translation_page_entry_array[
                                    entry_index] = tep->next;
                        else
                                prev->next = tep->next;
                        return;
}
                prev = tep;
#endif
                tep = tep->next;
        }
        if (tep == NULL)
                return;

        if (!tep->page_is_potentially_in_use)
                return;

        tep->page_is_potentially_in_use = 0;
        memset(&tep->chunk[0], 0, sizeof(tep->chunk));
        memset(&tep->flags[0], 0, sizeof(tep->flags));
}


/*
 *  bintrans_invalidate():
 *
 *  Invalidate translations containing a certain physical address.
 */
void bintrans_invalidate(struct cpu *cpu, uint64_t paddr)
{
        if (cpu->machine->old_bintrans_enable) {
                old_bintrans_invalidate(cpu, paddr);
                return;
        }

        /*  TODO  */
        /*  printf("bintrans_invalidate(): TODO\n");  */
}


/*
 *  bintrans_restart():
 *
 *  Starts over by throwing away the bintrans cache contents.
 */
void bintrans_restart(struct cpu *cpu)
{
        int i, n = 1 << BINTRANS_CACHE_N_INDEX_BITS;

        if (cpu->machine->arch != ARCH_MIPS)
                return;

        for (i=0; i<n; i++)
                cpu->mem->translation_page_entry_array[i] = NULL;

        cpu->mem->translation_code_chunk_space_head = 0;
        cpu->mem->n_quick_jumps = 0;

        debug("[ bintrans: Starting over! ]\n");
        clear_all_chunks_from_all_tables(cpu);
}


/*
 *  enter_chunks_into_tables():
 */
static void enter_chunks_into_tables(struct cpu *cpu, uint64_t vaddr,
        uint32_t *chunk0)
{
        int a, b;
        struct vth32_table *tbl1;

        switch (cpu->cd.mips.cpu_type.mmu_model) {
        case MMU3K:
                a = (vaddr >> 22) & 0x3ff;
                b = (vaddr >> 12) & 0x3ff;
                tbl1 = cpu->cd.mips.vaddr_to_hostaddr_table0_kernel[a];
                if (tbl1->haddr_entry[b*2] != NULL)
                        tbl1->bintrans_chunks[b] = chunk0;
                break;
        default:
                ;
        }
}


/*
 *  old_bintrans_attempt_translate():
 *
 *  Attempt to translate a chunk of code, starting at 'paddr'. If successful,
 *  the code chunk is run.
 *
 *  Returns the number of executed instructions.
 */
int old_bintrans_attempt_translate(struct cpu *cpu, uint64_t paddr)
{
        uint64_t paddr_page;
        int offset_within_page;
        int entry_index;
        unsigned char *host_mips_page;
        unsigned char *ca, *ca_justdid, *ca2;
        int res, hi6, special6, regimm5;
        unsigned char instr[4];
        int old_n_executed;
        size_t p;
        int try_to_translate;
        int n_translated, translated;
        unsigned char *f;
        struct translation_page_entry *tep;
        size_t chunk_len;
        int rs,rt,rd,sa,imm;
        uint32_t *potential_chunk_p;    /*  for branches  */
        int byte_order_cached_bigendian;
        int delayed_branch, stop_after_delayed_branch, return_code_written;
        uint64_t delayed_branch_new_p;
        int prev_p;


        /*  Abort if the current "environment" isn't safe enough:  */
        if (cpu->cd.mips.delay_slot || cpu->cd.mips.nullify_next ||
            (paddr & 3) != 0)
                return cpu->cd.mips.bintrans_instructions_executed;

        byte_order_cached_bigendian = (cpu->byte_order == EMUL_BIG_ENDIAN);

        /*  Is this a part of something that is already translated?  */
        paddr_page = paddr & ~0xfff;
        offset_within_page = (paddr & 0xfff) >> 2;
        entry_index = PADDR_TO_INDEX(paddr);
        tep = cpu->mem->translation_page_entry_array[entry_index];
        while (tep != NULL) {
                if (tep->paddr == paddr_page) {
                        int mask;

                        if (tep->chunk[offset_within_page] != 0) {
                                f = (size_t)tep->chunk[offset_within_page] +
                                    cpu->mem->translation_code_chunk_space;
                                goto run_it;    /*  see further down  */
                        }

                        mask = 1 << (offset_within_page & 7);
                        if (tep->flags[offset_within_page >> 3] & mask)
                                return cpu->cd.mips.
                                    bintrans_instructions_executed;
                        break;
                }
                tep = tep->next;
        }

#if 1
/*  printf("A paddr=%016llx\n", (long long)paddr);  */
/*  Sometimes this works.  */
quick_attempt_translate_again:
#endif
/*printf("B: ");
printf("v=%016llx p=%016llx h=%p paddr=%016llx\n",
(long long)cpu->cd.mips.pc_last_virtual_page,
(long long)cpu->cd.mips.pc_last_physical_page,
cpu->cd.mips.pc_last_host_4k_page,(long long)paddr);
*/
        /*
         *  If the chunk space is all used up, we need to start over from
         *  an empty chunk space.
         */
        if (cpu->mem->translation_code_chunk_space_head >=
            cpu->machine->bintrans_size) {
                bintrans_restart(cpu);
                tep = NULL;
        }


        host_mips_page = cpu->cd.mips.pc_bintrans_host_4kpage;
        if (host_mips_page == NULL)
                return cpu->cd.mips.bintrans_instructions_executed;


        if (tep == NULL) {
                /*  Allocate a new translation page entry:  */
                tep = (void *)(size_t) (cpu->mem->translation_code_chunk_space
                    + cpu->mem->translation_code_chunk_space_head);
                cpu->mem->translation_code_chunk_space_head +=
                    sizeof(struct translation_page_entry);

                /*  ... and align again:  */
                cpu->mem->translation_code_chunk_space_head =
                    ((cpu->mem->translation_code_chunk_space_head - 1) | 31)+1;

                /*  Add the entry to the array:  */
                memset(tep, 0, sizeof(struct translation_page_entry));
                tep->next = cpu->mem->translation_page_entry_array[entry_index];
                cpu->mem->translation_page_entry_array[entry_index] = tep;
                tep->paddr = paddr_page;
        }

        /*  printf("translation_page_entry_array[%i] = %p, ofs = %i\n",
            entry_index, cpu->mem->translation_page_entry_array[entry_index],
            offset_within_page);  */

        /*  ca is the "chunk address"; where to start generating a chunk:  */
        ca = cpu->mem->translation_code_chunk_space
            + cpu->mem->translation_code_chunk_space_head;


        /*
         *  Make sure that this page will not be written to by translated
         *  code:
         */
        mips_invalidate_translation_caches_paddr(cpu, paddr,
            JUST_MARK_AS_NON_WRITABLE);

        /*
         *  Try to translate a chunk of code:
         */
        p = paddr & 0xfff;
        prev_p = p >> 2;
        try_to_translate = 1;
        n_translated = 0;
        res = 0;
        return_code_written = 0;
        delayed_branch = 0;
        stop_after_delayed_branch = 0;
        delayed_branch_new_p = 0;
        rt = 0;
        cpu->mem->n_quick_jumps = cpu->mem->quick_jumps_index = 0;

        while (try_to_translate) {
                ca_justdid = ca;
                translated = 0;

                /*  Read an instruction word from host memory:  */
                *((uint32_t *)&instr[0]) = *((uint32_t *)(host_mips_page + p));

                if (byte_order_cached_bigendian) {
                        int tmp;
                        tmp = instr[0]; instr[0] = instr[3]; instr[3] = tmp;
                        tmp = instr[1]; instr[1] = instr[2]; instr[2] = tmp;
                }

                hi6 = instr[3] >> 2;

                /*  Check for instructions that can be translated:  */
                switch (hi6) {

                case HI6_SPECIAL:
                        special6 = instr[0] & 0x3f;
                        rs = ((instr[3] & 3) << 3) + ((instr[2] >> 5) & 7);
                        rd = (instr[1] >> 3) & 31;
                        rt = instr[2] & 31;
                        sa = ((instr[1] & 7) << 2) + ((instr[0] >> 6) & 3);
                        switch (special6) {
                        case SPECIAL_JR:
                        case SPECIAL_JALR:
                                translated = try_to_translate =
                                    bintrans_write_instruction__jr(&ca, rs, rd,
                                    special6);
                                n_translated += translated;
                                delayed_branch = 2;
                                delayed_branch_new_p = -1;      /*  anything,
                                            not within this physical page  */
                                if (special6 == SPECIAL_JR)
                                        stop_after_delayed_branch = 1;
                                break;
                        case SPECIAL_SYSCALL:
                        case SPECIAL_BREAK:
                                if (cpu->machine->userland_emul != NULL) {
                                        int mask = 1 << (prev_p & 7);
                                        bintrans_write_chunkreturn_fail(&ca);
                                        tep->flags[prev_p >> 3] |= mask;
                                        try_to_translate = 0;
                                        return_code_written = 1;
                                } else {
                                        translated = bintrans_write_instruction__tlb_rfe_etc(&ca,
                                            special6 == SPECIAL_BREAK? CALL_BREAK : CALL_SYSCALL);
                                        n_translated += translated;
                                        try_to_translate = 0;
                                }
                                break;
                        case SPECIAL_ADDU:
                        case SPECIAL_DADDU:
                        case SPECIAL_SUBU:
                        case SPECIAL_DSUBU:
                        case SPECIAL_AND:
                        case SPECIAL_OR:
                        case SPECIAL_NOR:
                        case SPECIAL_XOR:
                        case SPECIAL_SLL:
                        case SPECIAL_SLLV:
                        case SPECIAL_DSLL:
                        case SPECIAL_DSLL32:
                        case SPECIAL_SRA:
                        case SPECIAL_SRAV:
                        case SPECIAL_SRLV:
                        case SPECIAL_SRL:
                        case SPECIAL_DSRA:
                        case SPECIAL_DSRA32:
                        case SPECIAL_DSRL:
                        case SPECIAL_DSRL32:
                        case SPECIAL_SLT:
                        case SPECIAL_SLTU:
                        case SPECIAL_MOVZ:
                        case SPECIAL_MOVN:
                        case SPECIAL_DIV:
                        case SPECIAL_DIVU:
                        case SPECIAL_MULT:
                        case SPECIAL_MULTU:
                        case SPECIAL_SYNC:
                                /*  treat SYNC as a nop :-)  */
                                if (special6 == SPECIAL_SYNC) {
                                        rd = rt = rs = sa = 0;
                                        special6 = SPECIAL_SLL;
                                }
                                translated = try_to_translate = bintrans_write_instruction__addu_etc(cpu->mem, &ca, rd, rs, rt, sa, special6);
                                n_translated += translated;
                                break;
                        case SPECIAL_MFHI:
                        case SPECIAL_MFLO:
                        case SPECIAL_MTHI:
                        case SPECIAL_MTLO:
                                translated = try_to_translate = bintrans_write_instruction__mfmthilo(&ca,
                                    (special6 == SPECIAL_MFHI || special6 == SPECIAL_MFLO)? rd : rs,
                                    special6 == SPECIAL_MFHI || special6 == SPECIAL_MFLO,
                                    special6 == SPECIAL_MFHI || special6 == SPECIAL_MTHI);
                                n_translated += translated;
                                break;
                        default:
                                /*  Untranslatable:  */
                                /*  TODO: this code should only be in one place  */
                                bintrans_write_chunkreturn_fail(&ca);
                                {
                                        int mask = 1 << (prev_p & 7);
                                        tep->flags[prev_p >> 3] |= mask;
                                }
                                try_to_translate = 0;
                                return_code_written = 1;
                        }
                        break;

                case HI6_REGIMM:
                        regimm5 = instr[2] & 0x1f;
                        switch (regimm5) {
                        case REGIMM_BLTZ:
                        case REGIMM_BGEZ:
                                rs = ((instr[3] & 3) << 3) + ((instr[2] >> 5) & 7);
                                imm = (instr[1] << 8) + instr[0];
                                if (imm >= 32768)
                                        imm -= 65536;  
                                translated = try_to_translate = bintrans_write_instruction__branch(&ca, hi6, regimm5, rt, rs, imm);
                                n_translated += translated;
                                delayed_branch = 2;
                                delayed_branch_new_p = p + 4 + 4*imm;
                                break;
                        default:
                                /*  Untranslatable:  */
                                /*  TODO: this code should only be in one place  */
                                bintrans_write_chunkreturn_fail(&ca);
                                {
                                        int mask = 1 << (prev_p & 7);
                                        tep->flags[prev_p >> 3] |= mask;
                                }
                                try_to_translate = 0;
                                return_code_written = 1;
                        }
                        break;

                case HI6_J:
                case HI6_JAL:
                        imm = (((instr[3] & 3) << 24) + (instr[2] << 16) +
                            (instr[1] << 8) + instr[0]) & 0x03ffffff;
                        translated = try_to_translate = bintrans_write_instruction__jal(&ca, imm, hi6 == HI6_JAL);
                        n_translated += translated;
                        delayed_branch = 2;
                        delayed_branch_new_p = -1;
                        if (hi6 == HI6_J)
                                stop_after_delayed_branch = 1;
                        break;

                case HI6_BEQ:
                case HI6_BEQL:
                case HI6_BNE:
                case HI6_BNEL:
                case HI6_BLEZ:
                case HI6_BLEZL:
                case HI6_BGTZ:
                case HI6_BGTZL:
                        rs = ((instr[3] & 3) << 3) + ((instr[2] >> 5) & 7);
                        rt = instr[2] & 31;
                        imm = (instr[1] << 8) + instr[0];
                        if (imm >= 32768)
                                imm -= 65536;
                        translated = try_to_translate = bintrans_write_instruction__branch(&ca, hi6, 0, rt, rs, imm);
                        n_translated += translated;
                        delayed_branch = 2;
                        delayed_branch_new_p = p + 4 + 4*imm;
                        break;

                case HI6_ADDI:
                case HI6_ADDIU:
                case HI6_SLTI:
                case HI6_SLTIU:
                case HI6_ANDI:
                case HI6_ORI:
                case HI6_XORI:
                case HI6_DADDI:
                case HI6_DADDIU:
                        translated = try_to_translate =
                            bintrans_write_instruction__addiu_etc(cpu->mem,
                            &ca, instr[2] & 31,
                            ((instr[3] & 3) << 3) + ((instr[2] >> 5) & 7),
                            (instr[1] << 8) + instr[0], hi6);
                        n_translated += translated;
                        break;

                case HI6_LUI:
                        translated = try_to_translate =
                            bintrans_write_instruction__lui(&ca,
                            instr[2] & 31, (instr[1] << 8) + instr[0]);
                        n_translated += translated;
                        break;

                case HI6_COP0:
                        switch (instr[3]) {
                        case 0x40:
                                if (instr[0] == 0 && (instr[1]&7)==0) {
                                        if ((instr[2] & 0xe0)==0) {
                                                /*  mfc0:  */
                                                rt = instr[2] & 31;
                                                rd = (instr[1] >> 3) & 31;
                                                translated = try_to_translate = bintrans_write_instruction__mfc_mtc(cpu->mem, &ca, 0, 0, rt, rd, 0);
                                                n_translated += translated;
                                        } else if ((instr[2] & 0xe0)==0x20) {
                                                /*  dmfc0:  */
                                                rt = instr[2] & 31;
                                                rd = (instr[1] >> 3) & 31;
                                                translated = try_to_translate = bintrans_write_instruction__mfc_mtc(cpu->mem, &ca, 0, 1, rt, rd, 0);
                                                n_translated += translated;
                                        } else if ((instr[2] & 0xe0)==0x80) {
                                                /*  mtc0:  */
                                                rt = instr[2] & 31;
                                                rd = (instr[1] >> 3) & 31;
                                                translated = try_to_translate = bintrans_write_instruction__mfc_mtc(cpu->mem, &ca, 0, 0, rt, rd, 1);
                                                n_translated += translated;
                                        } else if ((instr[2] & 0xe0)==0xa0) {
                                                /*  dmtc0:  */
                                                rt = instr[2] & 31;
                                                rd = (instr[1] >> 3) & 31;
                                                translated = try_to_translate = bintrans_write_instruction__mfc_mtc(cpu->mem, &ca, 0, 1, rt, rd, 1);
                                                n_translated += translated;
                                        }
                                } else {
                                        /*  Untranslatable:  */
                                        /*  TODO: this code should only be in one place  */
                                        bintrans_write_chunkreturn_fail(&ca);
                                        {
                                                int mask = 1 << (prev_p & 7);
                                                tep->flags[prev_p >> 3] |= mask;
                                        }
                                        try_to_translate = 0;
                                        return_code_written = 1;
                                }
                                break;
                        case 0x42:
                                if (instr[2] == 0x00 && instr[1] == 0x00 && instr[0] == 0x10) {
                                        /*  rfe:  */
                                        translated = bintrans_write_instruction__tlb_rfe_etc(&ca, CALL_RFE);
                                        n_translated += translated;
                                        try_to_translate = 0;
                                } else if (instr[2] == 0x00 && instr[1] == 0x00 && instr[0] == 0x18) {
                                        /*  eret:  */
                                        translated = bintrans_write_instruction__tlb_rfe_etc(&ca, CALL_ERET);
                                        n_translated += translated;
                                        try_to_translate = 0;
                                } else if (instr[2] == 0 && instr[1] == 0 && instr[0] == 2) {
                                        /*  tlbwi:  */
                                        translated = try_to_translate = bintrans_write_instruction__tlb_rfe_etc(&ca, CALL_TLBWI);
                                        n_translated += translated;
                                } else if (instr[2] == 0 && instr[1] == 0 && instr[0] == 6) {
                                        /*  tlbwr:  */
                                        translated = try_to_translate = bintrans_write_instruction__tlb_rfe_etc(&ca, CALL_TLBWR);
                                        n_translated += translated;
                                } else if (instr[2] == 0 && instr[1] == 0 && instr[0] == 8) {
                                        /*  tlbp:  */
                                        translated = try_to_translate = bintrans_write_instruction__tlb_rfe_etc(&ca, CALL_TLBP);
                                        n_translated += translated;
                                } else if (instr[2] == 0 && instr[1] == 0 && instr[0] == 1) {
                                        /*  tlbr:  */
                                        translated = try_to_translate = bintrans_write_instruction__tlb_rfe_etc(&ca, CALL_TLBR);
                                        n_translated += translated;
                                } else if (instr[2] == 0 && instr[1] == 0 && (instr[0] == 0x20 || instr[0] == 0x21 || instr[0] == 0x22)) {
                                        /*  idle, standby and suspend on VR41xx etc ==> NOP  */
                                        translated = try_to_translate = bintrans_write_instruction__addu_etc(cpu->mem, &ca, 0, 0, 0, 0, SPECIAL_SLL);
                                        n_translated += translated;
                                } else {
                                        /*  Untranslatable:  */
                                        /*  TODO: this code should only be in one place  */
                                        bintrans_write_chunkreturn_fail(&ca);
                                        {
                                                int mask = 1 << (prev_p & 7);
                                                tep->flags[prev_p >> 3] |= mask;
                                        }
                                        try_to_translate = 0;
                                        return_code_written = 1;
                                }
                                break;
                        default:
                                /*  Untranslatable:  */
                                /*  TODO: this code should only be in one place  */
                                bintrans_write_chunkreturn_fail(&ca);
                                {
                                        int mask = 1 << (prev_p & 7);
                                        tep->flags[prev_p >> 3] |= mask;
                                }
                                try_to_translate = 0;
                                return_code_written = 1;
                        }
                        break;
#if 0
                case HI6_LQ_MDMX:
#endif
                case HI6_LD:
                case HI6_LWU:
                case HI6_LW:
                case HI6_LWL:
                case HI6_LWR:
                case HI6_LHU:
                case HI6_LH:
                case HI6_LBU:
                case HI6_LB:
#if 0
                case HI6_SQ:
#endif
                case HI6_SD:
                case HI6_SW:
                case HI6_SWL:
                case HI6_SWR:
                case HI6_SH:
                case HI6_SB:
                        rs = ((instr[3] & 3) << 3) + ((instr[2] >> 5) & 7);
                        rt = instr[2] & 31;
                        imm = (instr[1] << 8) + instr[0];
                        if (imm >= 32768)
                                imm -= 65536;
                        translated = try_to_translate = bintrans_write_instruction__loadstore(cpu->mem, &ca, rt, imm, rs, hi6,
                            byte_order_cached_bigendian,
                            cpu->machine->dyntrans_alignment_check);
                        n_translated += translated;
                        break;

                case HI6_CACHE:
                        translated = try_to_translate = bintrans_write_instruction__addu_etc(cpu->mem, &ca, 0, 0, 0, 0, SPECIAL_SLL);
                        n_translated += translated;
                        break;

                default:
                        /*  Untranslatable:  */
                        /*  TODO: this code should only be in one place  */
                        bintrans_write_chunkreturn_fail(&ca);
                        {
                                int mask = 1 << (prev_p & 7);
                                tep->flags[prev_p >> 3] |= mask;
                        }
                        try_to_translate = 0;
                        return_code_written = 1;
                }

                if (translated && delayed_branch) {
                        delayed_branch --;
                        if (delayed_branch == 0) {
                                int forward;

                                /*
                                 *  p is 0x000 .. 0xffc. If the jump is to
                                 *  within the same page, then we can use
                                 *  the same translation page to check if
                                 *  there already is a translation.
                                 */
                                if ((delayed_branch_new_p & ~0xfff) == 0)
                                        potential_chunk_p =
                                            &tep->chunk[delayed_branch_new_p/4];
                                else
                                        potential_chunk_p = NULL;

                                forward = delayed_branch_new_p > p;

                                bintrans_write_instruction__delayedbranch(
                                    cpu->mem, &ca,
                                    potential_chunk_p, &tep->chunk[0], 0,
                                    delayed_branch_new_p & 0xfff, forward);

                                if (stop_after_delayed_branch)
                                        try_to_translate = 0;
                        }
                }

                if (translated) {
                        int i;

                        if (tep->chunk[prev_p] == 0)
                                tep->chunk[prev_p] = (uint32_t)
                                    ((size_t)ca_justdid -
                                    (size_t)cpu->mem->translation_code_chunk_space);

                        /*  Quickjump to the translated instruction from some
                            previous instruction?  */
                        for (i=0; i<cpu->mem->n_quick_jumps; i++)
                                if (cpu->mem->quick_jump_page_offset[i] == p)
                                        bintrans_write_quickjump(cpu->mem,
                                            cpu->mem->quick_jump_host_address[i],
                                            tep->chunk[prev_p]);
                }

                if (translated && try_to_translate && prev_p < 1023) {
                        int mask = 1 << ((prev_p+1) & 7);

                        if (tep->flags[(prev_p+1) >> 3] & mask
                            && !delayed_branch) {
                                bintrans_write_chunkreturn_fail(&ca);
                                try_to_translate = 0;
                                return_code_written = 1;
                                break;
                        }

                        /*  Glue together with previously translated code,
                            if any:  */
                        if (tep->chunk[prev_p+1] != 0 && !delayed_branch) {
                                bintrans_write_instruction__delayedbranch(cpu->mem,
                                    &ca, &tep->chunk[prev_p+1], NULL, 1, p+4, 1);
                                try_to_translate = 0;
                                return_code_written = 1;
                                /*  try_to_translate = 0;  */
                                break;
                        }

                        if (n_translated > 120 && !delayed_branch) {
                                bintrans_write_instruction__delayedbranch(cpu->mem,
                                    &ca, &tep->chunk[prev_p+1], NULL, 1, p+4, 1);
                                try_to_translate = 0;
                                return_code_written = 1;
                                break;
                        }
                }

                p += sizeof(instr);
                prev_p ++;

                /*  If we have reached a different (MIPS) page, then stop translating.  */
                if (p == 0x1000)
                        try_to_translate = 0;
        }

        tep->page_is_potentially_in_use = 1;

        /*  Not enough translated? Then abort.  */
        if (n_translated < 1) {
                int mask = 1 << (offset_within_page & 7);
                tep->flags[offset_within_page >> 3] |= mask;
                return cpu->cd.mips.bintrans_instructions_executed;
        }

        /*  ca2 = ptr to the head of the new code chunk  */
        ca2 = cpu->mem->translation_code_chunk_space +
            cpu->mem->translation_code_chunk_space_head;

        /*  Add return code:  */
        if (!return_code_written)
                bintrans_write_chunkreturn(&ca);

        /*  chunk_len = nr of bytes occupied by the new code chunk  */
        chunk_len = (size_t)ca - (size_t)ca2;

        /*  Invalidate the host's instruction cache, if necessary:  */
        bintrans_host_cacheinvalidate(ca2, chunk_len);

        cpu->mem->translation_code_chunk_space_head += chunk_len;

        /*  Align the code chunk space:  */
        cpu->mem->translation_code_chunk_space_head =
            ((cpu->mem->translation_code_chunk_space_head - 1) | 31) + 1;


        /*  RUN the code chunk:  */
        f = ca2;

run_it:
        /*  printf("BEFORE: pc=%016llx r31=%016llx\n",
            (long long)cpu->pc, (long long)cpu->cd.mips.gpr[31]); */

        enter_chunks_into_tables(cpu, cpu->pc, &tep->chunk[0]);

        old_n_executed = cpu->cd.mips.bintrans_instructions_executed;

        bintrans_runchunk(cpu, f);

        /*  printf("AFTER:  pc=%016llx r31=%016llx\n",
            (long long)cpu->pc, (long long)cpu->cd.mips.gpr[31]);  */

        if (!cpu->cd.mips.delay_slot && !cpu->cd.mips.nullify_next &&
            cpu->cd.mips.bintrans_instructions_executed < N_SAFE_BINTRANS_LIMIT
            && (cpu->pc & 3) == 0
            && cpu->cd.mips.bintrans_instructions_executed != old_n_executed) {
                int ok = 0, a, b;
                struct vth32_table *tbl1;

                if (cpu->mem->bintrans_32bit_only ||
                    (cpu->pc & 0xffffffff80000000ULL) == 0 ||
                    (cpu->pc & 0xffffffff80000000ULL) == 0xffffffff80000000ULL) {
                        /*  32-bit special case:  */
                        a = (cpu->pc >> 22) & 0x3ff;
                        b = (cpu->pc >> 12) & 0x3ff;

                        /*  TODO: There is a bug here; if caches are disabled, and
                            for some reason the code jumps to a different page, then
                            this would jump to code in the cache!  The fix is
                            to check for cache isolation, and if so, use the
                            kernel table. Otherwise use table0.  */

                        /*  tbl1 = cpu->cd.mips.vaddr_to_hostaddr_table0_kernel[a];  */

                        tbl1 = cpu->cd.mips.vaddr_to_hostaddr_table0[a];
                        if (tbl1->haddr_entry[b*2] != NULL) {
                                paddr = tbl1->paddr_entry[b] | (cpu->pc & 0xfff);
                                ok = 1;
                        }
                }

                /*  General case, or if the special case above failed:  */
                /*  (This may cause exceptions.)  */
                if (!ok) {
                        uint64_t old_pc = cpu->cd.mips.pc_last = cpu->pc;
                        ok = cpu->translate_address(cpu, cpu->pc, &paddr, FLAG_INSTR);

                        if (!ok && old_pc != cpu->pc) {
                                /*  pc is something like ...0080 or ...0000 or so.  */
                                paddr = cpu->pc & 0xfff;
                                ok = 1;

                                cpu->cd.mips.pc_last_host_4k_page = NULL;
                                cpu->cd.mips.pc_bintrans_host_4kpage = NULL;
                        }
                }

                if (ok) {
                        paddr_page = paddr & ~0xfff;
                        offset_within_page = (paddr & 0xfff) >> 2;
                        entry_index = PADDR_TO_INDEX(paddr);
                        tep = cpu->mem->translation_page_entry_array[entry_index];
                        while (tep != NULL) {
                                if (tep->paddr == paddr_page) {
                                        int mask;
                                        if (tep->chunk[offset_within_page] != 0) {
                                                f = (size_t)tep->chunk[offset_within_page] +
                                                    cpu->mem->translation_code_chunk_space;
                                                goto run_it;
                                        }
                                        mask = 1 << (offset_within_page & 7);
                                        if (tep->flags[offset_within_page >> 3] & mask)
                                                return cpu->cd.mips.bintrans_instructions_executed;
                                        break;
                                }
                                tep = tep->next;
                        }

#if 1
                        /*  We have no translation.  */
                        if ((cpu->pc & 0xdff00000) == 0x9fc00000 &&
                            cpu->machine->prom_emulation)
                                return cpu->cd.mips.bintrans_instructions_executed;

                        /*  This special hack might make the time spent
                            in the main cpu_run_instr() lower:  */
                        /*  TODO: This doesn't seem to work with R4000 etc?  */
                        if (cpu->mem->bintrans_32bit_only) {
                            /* || (cpu->pc & 0xffffffff80000000ULL) == 0 ||
                            (cpu->pc & 0xffffffff80000000ULL) == 0xffffffff80000000ULL) {  */
                                int ok = 1;
                                /*  32-bit special case:  */
                                a = (cpu->pc >> 22) & 0x3ff;
                                b = (cpu->pc >> 12) & 0x3ff;
                                if (cpu->cd.mips.vaddr_to_hostaddr_table0 !=
                                    cpu->cd.mips.vaddr_to_hostaddr_table0_kernel)
                                        ok = 0;
                                tbl1 = cpu->cd.mips.vaddr_to_hostaddr_table0_kernel[a];
                                if (ok && tbl1->haddr_entry[b*2] != NULL) {
                                        cpu->cd.mips.pc_last_virtual_page = cpu->pc & ~0xfff;
                                        cpu->cd.mips.pc_last_physical_page = paddr & ~0xfff;
                                        cpu->cd.mips.pc_last_host_4k_page = (unsigned char *)tbl1->haddr_entry[b*2];
                                        cpu->cd.mips.pc_bintrans_host_4kpage = cpu->cd.mips.pc_last_host_4k_page;
                                        cpu->cd.mips.pc_bintrans_paddr = paddr;

/*
printf("C: ");
printf("v=%016llx p=%016llx h=%p paddr=%016llx\n",
(long long)cpu->cd.mips.pc_last_virtual_page,
(long long)cpu->cd.mips.pc_last_physical_page,
cpu->cd.mips.pc_last_host_4k_page,(long long)paddr);
*/
                                        goto quick_attempt_translate_again;
                                }
                        }
#endif

                        /*  Return.  */
                }
        }

        return cpu->cd.mips.bintrans_instructions_executed;
}


/*
 *  bintrans_attempt_translate():
 *
 *  Attempt to translate a chunk of code, starting at 'paddr'. If successful,
 *  the code chunk is run.
 *
 *  Returns the number of executed instructions.
 */
int bintrans_attempt_translate(struct cpu *cpu, uint64_t paddr)
{
        if (cpu->machine->old_bintrans_enable)
                return old_bintrans_attempt_translate(cpu, paddr);

        /*  TODO  */
        /*  printf("bintrans_attempt_translate(): TODO\n");  */

        return 0;
}


/*
 *  old_bintrans_init_cpu():
 *
 *  This must be called for each cpu wishing to use bintrans. This should
 *  be called after bintrans_init(), but before any other function in this
 *  module.
 */
void old_bintrans_init_cpu(struct cpu *cpu)
{
        int i, offset;

        cpu->cd.mips.chunk_base_address        = cpu->mem->translation_code_chunk_space;
        cpu->cd.mips.bintrans_load_32bit       = bintrans_load_32bit;
        cpu->cd.mips.bintrans_store_32bit      = bintrans_store_32bit;
        cpu->cd.mips.bintrans_jump_to_32bit_pc = bintrans_jump_to_32bit_pc;
        cpu->cd.mips.bintrans_fast_tlbwri      = coproc_tlbwri;
        cpu->cd.mips.bintrans_fast_tlbpr       = coproc_tlbpr;
        cpu->cd.mips.bintrans_fast_rfe         = coproc_rfe;
        cpu->cd.mips.bintrans_fast_eret        = coproc_eret;
        cpu->cd.mips.bintrans_simple_exception = mips_cpu_cause_simple_exception;
        cpu->cd.mips.fast_vaddr_to_hostaddr    = fast_vaddr_to_hostaddr;

        /*  Initialize vaddr->hostaddr translation tables:  */
        cpu->cd.mips.vaddr_to_hostaddr_nulltable =
            zeroed_alloc(sizeof(struct vth32_table));

        /*  Data cache:  */
        offset = 0;
        cpu->cd.mips.vaddr_to_hostaddr_r2k3k_dcachetable =
            zeroed_alloc(sizeof(struct vth32_table));
        for (i=0; i<1024; i++) {
                cpu->cd.mips.vaddr_to_hostaddr_r2k3k_dcachetable->
                    haddr_entry[i*2] = (void *)((size_t)cpu->cd.mips.cache[0]+offset);
                cpu->cd.mips.vaddr_to_hostaddr_r2k3k_dcachetable->
                    haddr_entry[i*2+1] = (void *)((size_t)cpu->cd.mips.cache[0]+offset);
                offset = (offset + 4096) % cpu->cd.mips.cache_size[0];
        }
        cpu->cd.mips.vaddr_to_hostaddr_r2k3k_dcachetable->refcount = 1024;

        /*  1M entry cache stuff for R2K/3K:  */
        if (cpu->cd.mips.cpu_type.isa_level == 1) {
                cpu->cd.mips.huge_r2k3k_cache_table =
                    zeroed_alloc(1048576 * sizeof(unsigned char *));
#if 1
                for (i=0; i<1048576; i++) {
                        unsigned char *ptr = NULL;
                        if ((unsigned int)i < (0xa0000000ULL >> 12) ||
                            (unsigned int)i >= (0xc0000000ULL >> 12))
                                ptr = cpu->cd.mips.
                                    vaddr_to_hostaddr_r2k3k_dcachetable
                                    ->haddr_entry[(i & 1023) * 2];
                        cpu->cd.mips.huge_r2k3k_cache_table[i] = ptr;
                }
#endif
        }

        /*  Instruction cache:  */
        offset = 0;
        cpu->cd.mips.vaddr_to_hostaddr_r2k3k_icachetable =
            zeroed_alloc(sizeof(struct vth32_table));
        for (i=0; i<1024; i++) {
                cpu->cd.mips.vaddr_to_hostaddr_r2k3k_icachetable->
                    haddr_entry[i*2] =
                    (void *)((size_t)cpu->cd.mips.cache[1]+offset);
                cpu->cd.mips.vaddr_to_hostaddr_r2k3k_icachetable->
                    haddr_entry[i*2+1] =
                    (void *)((size_t)cpu->cd.mips.cache[1]+offset);
                offset = (offset + 4096) % cpu->cd.mips.cache_size[1];
        }
        cpu->cd.mips.vaddr_to_hostaddr_r2k3k_icachetable->refcount = 1024;

        cpu->cd.mips.vaddr_to_hostaddr_table0_kernel =
            zeroed_alloc(1024 * sizeof(struct vth32_table *));
        cpu->cd.mips.vaddr_to_hostaddr_table0_user =
            zeroed_alloc(1024 * sizeof(struct vth32_table *));
        cpu->cd.mips.vaddr_to_hostaddr_table0_cacheisol_i =
            zeroed_alloc(1024 * sizeof(struct vth32_table *));
        cpu->cd.mips.vaddr_to_hostaddr_table0_cacheisol_d =
            zeroed_alloc(1024 * sizeof(struct vth32_table *));

        for (i=0; i<1024; i++) {
                cpu->cd.mips.vaddr_to_hostaddr_table0_kernel[i] = cpu->cd.mips.vaddr_to_hostaddr_nulltable;
                cpu->cd.mips.vaddr_to_hostaddr_table0_user[i] = cpu->cd.mips.vaddr_to_hostaddr_nulltable;
                cpu->cd.mips.vaddr_to_hostaddr_table0_cacheisol_i[i] = cpu->cd.mips.vaddr_to_hostaddr_r2k3k_icachetable;
                cpu->cd.mips.vaddr_to_hostaddr_table0_cacheisol_d[i] = cpu->cd.mips.vaddr_to_hostaddr_r2k3k_dcachetable;
        }

        cpu->cd.mips.vaddr_to_hostaddr_table0 = cpu->cd.mips.vaddr_to_hostaddr_table0_kernel;

        cpu->mem->bintrans_32bit_only = (cpu->cd.mips.cpu_type.isa_level <= 2
            || cpu->cd.mips.cpu_type.isa_level == 32);
}


/*
 *  bintrans_init_cpu():
 *
 *  This must be called for each cpu wishing to use bintrans. This should
 *  be called after bintrans_init(), but before any other function in this
 *  module.
 */
void bintrans_init_cpu(struct cpu *cpu)
{
        if (cpu->machine->old_bintrans_enable) {
                old_bintrans_init_cpu(cpu);
                return;
        }

        /*  TODO  */
        debug("\nbintrans_init_cpu(): New bintrans: TODO");
}


/*
 *  bintrans_init():
 *
 *  Should be called before any other bintrans_*() function is used.
 */
void bintrans_init(struct machine *machine, struct memory *mem)
{
        int res, i, n = 1 << BINTRANS_CACHE_N_INDEX_BITS;
        size_t s;

        mem->translation_page_entry_array = malloc(sizeof(
            struct translation_page_entry *) *
            (1 << BINTRANS_CACHE_N_INDEX_BITS));
        if (mem->translation_page_entry_array == NULL) {
                fprintf(stderr, "old_bintrans_init(): out of memory\n");
                exit(1);
        }

        /*
         *  The entry array must be NULLed, as these are pointers to
         *  translation page entries.
         */
        for (i=0; i<n; i++)
                mem->translation_page_entry_array[i] = NULL;

        /*  Allocate the large code chunk space:  */
        s = machine->bintrans_size + CODE_CHUNK_SPACE_MARGIN;
        mem->translation_code_chunk_space = (unsigned char *) mmap(NULL, s,
            PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_PRIVATE, -1, 0);

        /*  If mmap() failed, try malloc():  */
        if (mem->translation_code_chunk_space == NULL) {
                mem->translation_code_chunk_space = malloc(s);
                if (mem->translation_code_chunk_space == NULL) {
                        fprintf(stderr, "old_bintrans_init(): out of "
                            "memory (2)\n");
                        exit(1);
                }
        }

        debug("OLD bintrans: "BACKEND_NAME", %i MB translation cache at %p\n",
            (int)(s/1048576), mem->translation_code_chunk_space);

        /*
         *  The translation_code_chunk_space does not need to be zeroed,
         *  but the pointers to where in the chunk space we are about to
         *  add new chunks must be initialized to the beginning of the
         *  chunk space.
         */
        mem->translation_code_chunk_space_head = 0;

        /*
         *  Some operating systems (for example OpenBSD using the default
         *  stack protection settings in GCC) don't allow code to be 
         *  dynamically created in memory and executed. This will attempt
         *  to enable execution of the code chunk space.
         *
         *  NOTE/TODO: A Linux man page for mprotect from 1997 says that
         *  "POSIX.1b says that mprotect can be used only on regions
         *  of memory obtained from mmap(2).".  If malloc() isn't implemented
         *  using mmap(), then this could be a problem.
         */
        res = mprotect((void *)mem->translation_code_chunk_space,
            s, PROT_READ | PROT_WRITE | PROT_EXEC);
        if (res)
                debug("warning: mprotect() failed with errno %i."
                    " this usually doesn't really matter...\n", errno);

        bintrans_backend_init();

        if (!machine->old_bintrans_enable) {
                debug("bintrans_init(): TODO: New bintrans (?)\n");
        }
}


#endif  /*  BINTRANS  */