Archipelago » qemu

/*

 *  i386 emulator main execution loop

 * 

 *  Copyright (c) 2003 Fabrice Bellard

 *

 * 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, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include "exec-i386.h"

#include "disas.h"

//#define DEBUG_EXEC

#define DEBUG_FLUSH

//#define DEBUG_SIGNAL

/* main execution loop */

/* maximum total translate dcode allocated */

#define CODE_GEN_BUFFER_SIZE     (2048 * 1024)

//#define CODE_GEN_BUFFER_SIZE     (128 * 1024)

#define CODE_GEN_MAX_SIZE        65536

#define CODE_GEN_ALIGN           16 /* must be >= of the size of a icache line */

/* threshold to flush the translated code buffer */

#define CODE_GEN_BUFFER_MAX_SIZE (CODE_GEN_BUFFER_SIZE - CODE_GEN_MAX_SIZE)

#define CODE_GEN_MAX_BLOCKS    (CODE_GEN_BUFFER_SIZE / 64)

#define CODE_GEN_HASH_BITS     15

#define CODE_GEN_HASH_SIZE     (1 << CODE_GEN_HASH_BITS)

typedef struct TranslationBlock {

    unsigned long pc;   /* simulated PC corresponding to this block (EIP + CS base) */

    unsigned long cs_base; /* CS base for this block */

    unsigned int flags; /* flags defining in which context the code was generated */

    uint8_t *tc_ptr;    /* pointer to the translated code */

    struct TranslationBlock *hash_next; /* next matching block */

} TranslationBlock;

TranslationBlock tbs[CODE_GEN_MAX_BLOCKS];

TranslationBlock *tb_hash[CODE_GEN_HASH_SIZE];

int nb_tbs;

uint8_t code_gen_buffer[CODE_GEN_BUFFER_SIZE];

uint8_t *code_gen_ptr;

/* thread support */

#ifdef __powerpc__

static inline int testandset (int *p)

{

    int ret;

    __asm__ __volatile__ (

                          "0:    lwarx %0,0,%1 ;"

                          "      xor. %0,%3,%0;"

                          "      bne 1f;"

                          "      stwcx. %2,0,%1;"

                          "      bne- 0b;"

                          "1:    "

                          : "=&r" (ret)

                          : "r" (p), "r" (1), "r" (0)

                          : "cr0", "memory");

    return ret;

}

#endif

#ifdef __i386__

static inline int testandset (int *p)

{

    char ret;

    long int readval;

    __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"

                          : "=q" (ret), "=m" (*p), "=a" (readval)

                          : "r" (1), "m" (*p), "a" (0)

                          : "memory");

    return ret;

}

#endif

#ifdef __s390__

static inline int testandset (int *p)

{

    int ret;

    __asm__ __volatile__ ("0: cs    %0,%1,0(%2)\n"

                          "   jl    0b"

                          : "=&d" (ret)

                          : "r" (1), "a" (p), "0" (*p) 

                          : "cc", "memory" );

    return ret;

}

#endif

#ifdef __alpha__

int testandset (int *p)

{

    int ret;

    unsigned long one;

    __asm__ __volatile__ ("0:        mov 1,%2\n"

                          "        ldl_l %0,%1\n"

                          "        stl_c %2,%1\n"

                          "        beq %2,1f\n"

                          ".subsection 2\n"

                          "1:        br 0b\n"

                          ".previous"

                          : "=r" (ret), "=m" (*p), "=r" (one)

                          : "m" (*p));

    return ret;

}

#endif

#ifdef __sparc__

static inline int testandset (int *p)

{

        int ret;

        __asm__ __volatile__("ldstub        [%1], %0"

                             : "=r" (ret)

                             : "r" (p)

                             : "memory");

        return (ret ? 1 : 0);

}

#endif

int global_cpu_lock = 0;

void cpu_lock(void)

{

    while (testandset(&global_cpu_lock));

}

void cpu_unlock(void)

{

    global_cpu_lock = 0;

}

/* exception support */

/* NOTE: not static to force relocation generation by GCC */

void raise_exception_err(int exception_index, int error_code)

{

    /* NOTE: the register at this point must be saved by hand because

       longjmp restore them */

#ifdef reg_EAX

    env->regs[R_EAX] = EAX;

#endif

#ifdef reg_ECX

    env->regs[R_ECX] = ECX;

#endif

#ifdef reg_EDX

    env->regs[R_EDX] = EDX;

#endif

#ifdef reg_EBX

    env->regs[R_EBX] = EBX;

#endif

#ifdef reg_ESP

    env->regs[R_ESP] = ESP;

#endif

#ifdef reg_EBP

    env->regs[R_EBP] = EBP;

#endif

#ifdef reg_ESI

    env->regs[R_ESI] = ESI;

#endif

#ifdef reg_EDI

    env->regs[R_EDI] = EDI;

#endif

    env->exception_index = exception_index;

    env->error_code = error_code;

    longjmp(env->jmp_env, 1);

}

/* short cut if error_code is 0 or not present */

void raise_exception(int exception_index)

{

    raise_exception_err(exception_index, 0);

}

void cpu_x86_tblocks_init(void)

{

    if (!code_gen_ptr) {

        code_gen_ptr = code_gen_buffer;

    }

}

/* flush all the translation blocks */

static void tb_flush(void)

{

    int i;

#ifdef DEBUG_FLUSH

    printf("gemu: flush code_size=%d nb_tbs=%d avg_tb_size=%d\n", 

           code_gen_ptr - code_gen_buffer, 

           nb_tbs, 

           (code_gen_ptr - code_gen_buffer) / nb_tbs);

#endif

    nb_tbs = 0;

    for(i = 0;i < CODE_GEN_HASH_SIZE; i++)

        tb_hash[i] = NULL;

    code_gen_ptr = code_gen_buffer;

    /* XXX: flush processor icache at this point */

}

/* find a translation block in the translation cache. If not found,

   return NULL and the pointer to the last element of the list in pptb */

static inline TranslationBlock *tb_find(TranslationBlock ***pptb,

                                        unsigned long pc, 

                                        unsigned long cs_base,

                                        unsigned int flags)

{

    TranslationBlock **ptb, *tb;

    unsigned int h;

    h = pc & (CODE_GEN_HASH_SIZE - 1);

    ptb = &tb_hash[h];

#if 0

    /* XXX: hack to handle 16 bit modyfing code */

    if (flags & (1 << GEN_FLAG_CODE32_SHIFT))

#endif

        for(;;) {

            tb = *ptb;

            if (!tb)

                break;

            if (tb->pc == pc && tb->cs_base == cs_base && tb->flags == flags)

            return tb;

            ptb = &tb->hash_next;

        }

    *pptb = ptb;

    return NULL;

}

/* allocate a new translation block. flush the translation buffer if

   too many translation blocks or too much generated code */

static inline TranslationBlock *tb_alloc(void)

{

    TranslationBlock *tb;

    if (nb_tbs >= CODE_GEN_MAX_BLOCKS || 

        (code_gen_ptr - code_gen_buffer) >= CODE_GEN_BUFFER_MAX_SIZE)

        tb_flush();

    tb = &tbs[nb_tbs++];

    return tb;

}

int cpu_x86_exec(CPUX86State *env1)

{

    int saved_T0, saved_T1, saved_A0;

    CPUX86State *saved_env;

#ifdef reg_EAX

    int saved_EAX;

#endif

#ifdef reg_ECX

    int saved_ECX;

#endif

#ifdef reg_EDX

    int saved_EDX;

#endif

#ifdef reg_EBX

    int saved_EBX;

#endif

#ifdef reg_ESP

    int saved_ESP;

#endif

#ifdef reg_EBP

    int saved_EBP;

#endif

#ifdef reg_ESI

    int saved_ESI;

#endif

#ifdef reg_EDI

    int saved_EDI;

#endif

    int code_gen_size, ret;

    void (*gen_func)(void);

    TranslationBlock *tb, **ptb;

    uint8_t *tc_ptr, *cs_base, *pc;

    unsigned int flags;

    /* first we save global registers */

    saved_T0 = T0;

    saved_T1 = T1;

    saved_A0 = A0;

    saved_env = env;

    env = env1;

#ifdef reg_EAX

    saved_EAX = EAX;

    EAX = env->regs[R_EAX];

#endif

#ifdef reg_ECX

    saved_ECX = ECX;

    ECX = env->regs[R_ECX];

#endif

#ifdef reg_EDX

    saved_EDX = EDX;

    EDX = env->regs[R_EDX];

#endif

#ifdef reg_EBX

    saved_EBX = EBX;

    EBX = env->regs[R_EBX];

#endif

#ifdef reg_ESP

    saved_ESP = ESP;

    ESP = env->regs[R_ESP];

#endif

#ifdef reg_EBP

    saved_EBP = EBP;

    EBP = env->regs[R_EBP];

#endif

#ifdef reg_ESI

    saved_ESI = ESI;

    ESI = env->regs[R_ESI];

#endif

#ifdef reg_EDI

    saved_EDI = EDI;

    EDI = env->regs[R_EDI];

#endif

    /* put eflags in CPU temporary format */

    CC_SRC = env->eflags & (CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);

    DF = 1 - (2 * ((env->eflags >> 10) & 1));

    CC_OP = CC_OP_EFLAGS;

    env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);

    env->interrupt_request = 0;

    /* prepare setjmp context for exception handling */

    if (setjmp(env->jmp_env) == 0) {

        for(;;) {

            if (env->interrupt_request) {

                raise_exception(EXCP_INTERRUPT);

            }

#ifdef DEBUG_EXEC

            if (loglevel) {

                /* XXX: save all volatile state in cpu state */

                /* restore flags in standard format */

                env->regs[R_EAX] = EAX;

                env->regs[R_EBX] = EBX;

                env->regs[R_ECX] = ECX;

                env->regs[R_EDX] = EDX;

                env->regs[R_ESI] = ESI;

                env->regs[R_EDI] = EDI;

                env->regs[R_EBP] = EBP;

                env->regs[R_ESP] = ESP;

                env->eflags = env->eflags | cc_table[CC_OP].compute_all() | (DF & DF_MASK);

                cpu_x86_dump_state(env, logfile, 0);

                env->eflags &= ~(DF_MASK | CC_O | CC_S | CC_Z | CC_A | CC_P | CC_C);

            }

#endif

            /* we compute the CPU state. We assume it will not

               change during the whole generated block. */

            flags = env->seg_cache[R_CS].seg_32bit << GEN_FLAG_CODE32_SHIFT;

            flags |= env->seg_cache[R_SS].seg_32bit << GEN_FLAG_SS32_SHIFT;

            flags |= (((unsigned long)env->seg_cache[R_DS].base | 

                       (unsigned long)env->seg_cache[R_ES].base |

                       (unsigned long)env->seg_cache[R_SS].base) != 0) << 

                GEN_FLAG_ADDSEG_SHIFT;

            if (!(env->eflags & VM_MASK)) {

                flags |= (env->segs[R_CS] & 3) << GEN_FLAG_CPL_SHIFT;

            } else {

                /* NOTE: a dummy CPL is kept */

                flags |= (1 << GEN_FLAG_VM_SHIFT);

                flags |= (3 << GEN_FLAG_CPL_SHIFT);

            }

            flags |= (env->eflags & IOPL_MASK) >> (12 - GEN_FLAG_IOPL_SHIFT);

            flags |= (env->eflags & TF_MASK) << (GEN_FLAG_TF_SHIFT - 8);

            cs_base = env->seg_cache[R_CS].base;

            pc = cs_base + env->eip;

            tb = tb_find(&ptb, (unsigned long)pc, (unsigned long)cs_base, 

                         flags);

            if (!tb) {

                /* if no translated code available, then translate it now */

                /* XXX: very inefficient: we lock all the cpus when

                   generating code */

                cpu_lock();

                tc_ptr = code_gen_ptr;

                ret = cpu_x86_gen_code(code_gen_ptr, CODE_GEN_MAX_SIZE, 

                                       &code_gen_size, pc, cs_base, flags);

                /* if invalid instruction, signal it */

                if (ret != 0) {

                    cpu_unlock();

                    raise_exception(EXCP06_ILLOP);

                }

                tb = tb_alloc();

                *ptb = tb;

                tb->pc = (unsigned long)pc;

                tb->cs_base = (unsigned long)cs_base;

                tb->flags = flags;

                tb->tc_ptr = tc_ptr;

                tb->hash_next = NULL;

                code_gen_ptr = (void *)(((unsigned long)code_gen_ptr + code_gen_size + CODE_GEN_ALIGN - 1) & ~(CODE_GEN_ALIGN - 1));

                cpu_unlock();

            }

#ifdef DEBUG_EXEC

            if (loglevel) {

                fprintf(logfile, "Trace 0x%08lx [0x%08lx] %s\n",

                        (long)tb->tc_ptr, (long)tb->pc,

                        lookup_symbol((void *)tb->pc));

            }

#endif

            /* execute the generated code */

            tc_ptr = tb->tc_ptr;

            gen_func = (void *)tc_ptr;

            gen_func();

        }

    }

    ret = env->exception_index;

    /* restore flags in standard format */

    env->eflags = env->eflags | cc_table[CC_OP].compute_all() | (DF & DF_MASK);

    /* restore global registers */

#ifdef reg_EAX

    EAX = saved_EAX;

#endif

#ifdef reg_ECX

    ECX = saved_ECX;

#endif

#ifdef reg_EDX

    EDX = saved_EDX;

#endif

#ifdef reg_EBX

    EBX = saved_EBX;

#endif

#ifdef reg_ESP

    ESP = saved_ESP;

#endif

#ifdef reg_EBP

    EBP = saved_EBP;

#endif

#ifdef reg_ESI

    ESI = saved_ESI;

#endif

#ifdef reg_EDI

    EDI = saved_EDI;

#endif

    T0 = saved_T0;

    T1 = saved_T1;

    A0 = saved_A0;

    env = saved_env;

    return ret;

}

void cpu_x86_interrupt(CPUX86State *s)

{

    s->interrupt_request = 1;

}

void cpu_x86_load_seg(CPUX86State *s, int seg_reg, int selector)

{

    CPUX86State *saved_env;

    saved_env = env;

    env = s;

    load_seg(seg_reg, selector);

    env = saved_env;

}

#undef EAX

#undef ECX

#undef EDX

#undef EBX

#undef ESP

#undef EBP

#undef ESI

#undef EDI

#undef EIP

#include <signal.h>

#include <sys/ucontext.h>

/* 'pc' is the host PC at which the exception was raised. 'address' is

   the effective address of the memory exception */

static inline int handle_cpu_signal(unsigned long pc,

                                    unsigned long address,

                                    sigset_t *old_set)

{

#ifdef DEBUG_SIGNAL

    printf("gemu: SIGSEGV pc=0x%08lx oldset=0x%08lx\n", 

           pc, *(unsigned long *)old_set);

#endif

    if (pc >= (unsigned long)code_gen_buffer &&

        pc < (unsigned long)code_gen_buffer + CODE_GEN_BUFFER_SIZE) {

        /* the PC is inside the translated code. It means that we have

           a virtual CPU fault */

        /* we restore the process signal mask as the sigreturn should

           do it */

        sigprocmask(SIG_SETMASK, old_set, NULL);

        /* XXX: need to compute virtual pc position by retranslating

           code. The rest of the CPU state should be correct. */

        env->cr2 = address;

        /* XXX: more precise exception code */

        raise_exception_err(EXCP0E_PAGE, 4);

        /* never comes here */

        return 1;

    } else {

        return 0;

    }

}

int cpu_x86_signal_handler(int host_signum, struct siginfo *info, 

                           void *puc)

{

#if defined(__i386__)

    struct ucontext *uc = puc;

    unsigned long pc;

    sigset_t *pold_set;

#ifndef REG_EIP

/* for glibc 2.1 */

#define REG_EIP EIP

#endif

    pc = uc->uc_mcontext.gregs[REG_EIP];

    pold_set = &uc->uc_sigmask;

    return handle_cpu_signal(pc, (unsigned long)info->si_addr, pold_set);

#else

#warning No CPU specific signal handler: cannot handle target SIGSEGV events

    return 0;

#endif

}