summaryrefslogtreecommitdiff
blob: a8d0ef6401ee7ff37005bf8cee98245ebedf5296 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
/*
 * 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

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);
        }
    }
}