/* * 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 SIGTEST 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 0x10100 static void 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); } // cpu_set_log(CPU_LOG_TB_IN_ASM | CPU_LOG_TB_OUT_ASM | CPU_LOG_EXEC); env = cpu_init("qemu32"); 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); } } }