/* * Example of use of user mode libqemu: launch a basic .com DOS * executable */#include <stdlib.h>#include <stdio.h>#include <string.h>#include <inttypes.h>#include <unistd.h>#include <fcntl.h>#include <sys/mman.h>#include <signal.h>#include <malloc.h>#include "cpu.h"//#define SIGTESTvoid cpu_outb(CPUState *env, int addr, int val){    fprintf(stderr, "outb: port=0x%04x, data=%02x\n", addr, val);}void cpu_outw(CPUState *env, int addr, int val){    fprintf(stderr, "outw: port=0x%04x, data=%04x\n", addr, val);}void cpu_outl(CPUState *env, int addr, int val){    fprintf(stderr, "outl: port=0x%04x, data=%08x\n", addr, val);}int cpu_inb(CPUState *env, int addr){    fprintf(stderr, "inb: port=0x%04x\n", addr);    return 0;}int cpu_inw(CPUState *env, int addr){    fprintf(stderr, "inw: port=0x%04x\n", addr);    return 0;}int cpu_inl(CPUState *env, int addr){    fprintf(stderr, "inl: port=0x%04x\n", addr);    return 0;}int cpu_get_pic_interrupt(CPUState *env){    return -1;}uint64_t cpu_get_tsc(CPUState *env){    return 0;}static void set_gate(void *ptr, unsigned int type, unsigned int dpl,                      unsigned long addr, unsigned int sel){    unsigned int e1, e2;    e1 = (addr & 0xffff) | (sel << 16);    e2 = (addr & 0xffff0000) | 0x8000 | (dpl << 13) | (type << 8);    stl((uint8_t *)ptr, e1);    stl((uint8_t *)ptr + 4, e2);}uint64_t idt_table[256];/* only dpl matters as we do only user space emulation */static void set_idt(int n, unsigned int dpl){    set_gate(idt_table + n, 0, dpl, 0, 0);}void qemu_free(void *ptr){    free(ptr);}void *qemu_malloc(size_t size){    return malloc(size);}void *qemu_mallocz(size_t size){    void *ptr;    ptr = qemu_malloc(size);    if (!ptr)        return NULL;    memset(ptr, 0, size);    return ptr;}void *qemu_vmalloc(size_t size){    return memalign(4096, size);}void qemu_vfree(void *ptr){    free(ptr);}void qemu_printf(const char *fmt, ...){    va_list ap;    va_start(ap, fmt);    vprintf(fmt, ap);    va_end(ap);}/* XXX: this is a bug in helper2.c */int errno;/**********************************************/#define COM_BASE_ADDR    0x10100void usage(void){    printf("qruncom version 0.1 (c) 2003 Fabrice Bellard\n"           "usage: qruncom file.com\n"           "user mode libqemu demo: run simple .com DOS executables\n");    exit(1);}static inline uint8_t *seg_to_linear(unsigned int seg, unsigned int reg){    return (uint8_t *)((seg << 4) + (reg & 0xffff));}static inline void pushw(CPUState *env, int val){    env->regs[R_ESP] = (env->regs[R_ESP] & ~0xffff) | ((env->regs[R_ESP] - 2) & 0xffff);    *(uint16_t *)seg_to_linear(env->segs[R_SS].selector, env->regs[R_ESP]) = val;}static void host_segv_handler(int host_signum, siginfo_t *info,                               void *puc){    if (cpu_signal_handler(host_signum, info, puc)) {        return;    }    abort();}int main(int argc, char **argv){    uint8_t *vm86_mem;    const char *filename;    int fd, ret, seg;    CPUState *env;    if (argc != 2)        usage();    filename = argv[1];        vm86_mem = mmap((void *)0x00000000, 0x110000,                     PROT_WRITE | PROT_READ | PROT_EXEC,                     MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);    if (vm86_mem == MAP_FAILED) {        perror("mmap");        exit(1);    }    /* load the MSDOS .com executable */    fd = open(filename, O_RDONLY);    if (fd < 0) {        perror(filename);        exit(1);    }    ret = read(fd, vm86_mem + COM_BASE_ADDR, 65536 - 256);    if (ret < 0) {        perror("read");        exit(1);    }    close(fd);    /* install exception handler for CPU emulator */    {        struct sigaction act;                sigfillset(&act.sa_mask);        act.sa_flags = SA_SIGINFO;        //        act.sa_flags |= SA_ONSTACK;        act.sa_sigaction = host_segv_handler;        sigaction(SIGSEGV, &act, NULL);        sigaction(SIGBUS, &act, NULL);#if defined (TARGET_I386) && defined(USE_CODE_COPY)        sigaction(SIGFPE, &act, NULL);#endif    }    //    cpu_set_log(CPU_LOG_TB_IN_ASM | CPU_LOG_TB_OUT_ASM | CPU_LOG_EXEC);    env = cpu_init();    /* disable code copy to simplify debugging */    code_copy_enabled = 0;    /* set user mode state (XXX: should be done automatically by       cpu_init ?) */    env->user_mode_only = 1;    cpu_x86_set_cpl(env, 3);    env->cr[0] = CR0_PG_MASK | CR0_WP_MASK | CR0_PE_MASK;    /* NOTE: hflags duplicates some of the virtual CPU state */    env->hflags |= HF_PE_MASK | VM_MASK;    /* flags setup : we activate the IRQs by default as in user       mode. We also activate the VM86 flag to run DOS code */    env->eflags |= IF_MASK | VM_MASK;        /* init basic registers */    env->eip = 0x100;    env->regs[R_ESP] = 0xfffe;    seg = (COM_BASE_ADDR - 0x100) >> 4;    cpu_x86_load_seg_cache(env, R_CS, seg,                            (seg << 4), 0xffff, 0);    cpu_x86_load_seg_cache(env, R_SS, seg,                            (seg << 4), 0xffff, 0);    cpu_x86_load_seg_cache(env, R_DS, seg,                            (seg << 4), 0xffff, 0);    cpu_x86_load_seg_cache(env, R_ES, seg,                            (seg << 4), 0xffff, 0);    cpu_x86_load_seg_cache(env, R_FS, seg,                            (seg << 4), 0xffff, 0);    cpu_x86_load_seg_cache(env, R_GS, seg,                            (seg << 4), 0xffff, 0);    /* exception support */    env->idt.base = (unsigned long)idt_table;    env->idt.limit = sizeof(idt_table) - 1;    set_idt(0, 0);    set_idt(1, 0);    set_idt(2, 0);    set_idt(3, 3);    set_idt(4, 3);    set_idt(5, 3);    set_idt(6, 0);    set_idt(7, 0);    set_idt(8, 0);    set_idt(9, 0);    set_idt(10, 0);    set_idt(11, 0);    set_idt(12, 0);    set_idt(13, 0);    set_idt(14, 0);    set_idt(15, 0);    set_idt(16, 0);    set_idt(17, 0);    set_idt(18, 0);    set_idt(19, 0);            /* put return code */    *seg_to_linear(env->segs[R_CS].selector, 0) = 0xb4; /* mov ah, $0 */    *seg_to_linear(env->segs[R_CS].selector, 1) = 0x00;    *seg_to_linear(env->segs[R_CS].selector, 2) = 0xcd; /* int $0x21 */    *seg_to_linear(env->segs[R_CS].selector, 3) = 0x21;    pushw(env, 0x0000);    /* the value of these registers seem to be assumed by pi_10.com */    env->regs[R_ESI] = 0x100;    env->regs[R_ECX] = 0xff;    env->regs[R_EBP] = 0x0900;    env->regs[R_EDI] = 0xfffe;    /* inform the emulator of the mmaped memory */    page_set_flags(0x00000000, 0x110000,                    PAGE_WRITE | PAGE_READ | PAGE_EXEC | PAGE_VALID);    for(;;) {        ret = cpu_x86_exec(env);        switch(ret) {        case EXCP0D_GPF:            {                int int_num, ah;                int_num = *(uint8_t *)(env->segs[R_CS].base + env->eip + 1);                if (int_num != 0x21)                    goto unknown_int;                ah = (env->regs[R_EAX] >> 8) & 0xff;                switch(ah) {                case 0x00: /* exit */                    exit(0);                case 0x02: /* write char */                    {                        uint8_t c = env->regs[R_EDX];                        write(1, &c, 1);                    }                    break;                case 0x09: /* write string */                    {                        uint8_t c;                        for(;;) {                            c = *seg_to_linear(env->segs[R_DS].selector, env->regs[R_EAX]);                            if (c == '$')                                break;                            write(1, &c, 1);                        }                        env->regs[R_EAX] = (env->regs[R_EAX] & ~0xff) | '$';                    }                    break;                default:                unknown_int:                    fprintf(stderr, "unsupported int 0x%02x\n", int_num);                    cpu_dump_state(env, stderr, fprintf, 0);                    //                    exit(1);                }                env->eip += 2;            }            break;        default:            fprintf(stderr, "unhandled cpu_exec return code (0x%x)\n", ret);            cpu_dump_state(env, stderr, fprintf, 0);            exit(1);        }    }}