1 /*---------------------------------------------------------------------------+
2 | get_address.c |
3 | |
4 | Get the effective address from an FPU instruction. |
5 | |
6 | Copyright (C) 1992,1993,1994,1997 |
7 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
8 | Australia. E-mail billm@suburbia.net |
9 | |
10 | |
11 +---------------------------------------------------------------------------*/
12
13 /*---------------------------------------------------------------------------+
14 | Note: |
15 | The file contains code which accesses user memory. |
16 | Emulator static data may change when user memory is accessed, due to |
17 | other processes using the emulator while swapping is in progress. |
18 +---------------------------------------------------------------------------*/
19
20 #include <linux/stddef.h>
21
22 #include <asm/uaccess.h>
23 #include <asm/desc.h>
24
25 #include "fpu_system.h"
26 #include "exception.h"
27 #include "fpu_emu.h"
28
29 #define FPU_WRITE_BIT 0x10
30
31 static int reg_offset[] = {
32 offsetof(struct info, ___eax),
33 offsetof(struct info, ___ecx),
34 offsetof(struct info, ___edx),
35 offsetof(struct info, ___ebx),
36 offsetof(struct info, ___esp),
37 offsetof(struct info, ___ebp),
38 offsetof(struct info, ___esi),
39 offsetof(struct info, ___edi)
40 };
41
42 #define REG_(x) (*(long *)(reg_offset[(x)]+(u_char *) FPU_info))
43
44 static int reg_offset_vm86[] = {
45 offsetof(struct info, ___cs),
46 offsetof(struct info, ___vm86_ds),
47 offsetof(struct info, ___vm86_es),
48 offsetof(struct info, ___vm86_fs),
49 offsetof(struct info, ___vm86_gs),
50 offsetof(struct info, ___ss),
51 offsetof(struct info, ___vm86_ds)
52 };
53
54 #define VM86_REG_(x) (*(unsigned short *) \
55 (reg_offset_vm86[((unsigned)x)]+(u_char *) FPU_info))
56
57 /* This dummy, gs is not saved on the stack. */
58 #define ___GS ___ds
59
60 static int reg_offset_pm[] = {
61 offsetof(struct info, ___cs),
62 offsetof(struct info, ___ds),
63 offsetof(struct info, ___es),
64 offsetof(struct info, ___fs),
65 offsetof(struct info, ___GS),
66 offsetof(struct info, ___ss),
67 offsetof(struct info, ___ds)
68 };
69
70 #define PM_REG_(x) (*(unsigned short *) \
71 (reg_offset_pm[((unsigned)x)]+(u_char *) FPU_info))
72
73 /* Decode the SIB byte. This function assumes mod != 0 */
74 static int sib(int mod, unsigned long *fpu_eip)
75 {
76 u_char ss, index, base;
77 long offset;
78
79 RE_ENTRANT_CHECK_OFF;
80 FPU_code_access_ok(1);
81 FPU_get_user(base, (u_char __user *) (*fpu_eip)); /* The SIB byte */
82 RE_ENTRANT_CHECK_ON;
83 (*fpu_eip)++;
84 ss = base >> 6;
85 index = (base >> 3) & 7;
86 base &= 7;
87
88 if ((mod == 0) && (base == 5))
89 offset = 0; /* No base register */
90 else
91 offset = REG_(base);
92
93 if (index == 4) {
94 /* No index register */
95 /* A non-zero ss is illegal */
96 if (ss)
97 EXCEPTION(EX_Invalid);
98 } else {
99 offset += (REG_(index)) << ss;
100 }
101
102 if (mod == 1) {
103 /* 8 bit signed displacement */
104 long displacement;
105 RE_ENTRANT_CHECK_OFF;
106 FPU_code_access_ok(1);
107 FPU_get_user(displacement, (signed char __user *)(*fpu_eip));
108 offset += displacement;
109 RE_ENTRANT_CHECK_ON;
110 (*fpu_eip)++;
111 } else if (mod == 2 || base == 5) { /* The second condition also has mod==0 */
112 /* 32 bit displacement */
113 long displacement;
114 RE_ENTRANT_CHECK_OFF;
115 FPU_code_access_ok(4);
116 FPU_get_user(displacement, (long __user *)(*fpu_eip));
117 offset += displacement;
118 RE_ENTRANT_CHECK_ON;
119 (*fpu_eip) += 4;
120 }
121
122 return offset;
123 }
124
125 static unsigned long vm86_segment(u_char segment, struct address *addr)
126 {
127 segment--;
128 #ifdef PARANOID
129 if (segment > PREFIX_SS_) {
130 EXCEPTION(EX_INTERNAL | 0x130);
131 math_abort(FPU_info, SIGSEGV);
132 }
133 #endif /* PARANOID */
134 addr->selector = VM86_REG_(segment);
135 return (unsigned long)VM86_REG_(segment) << 4;
136 }
137
138 /* This should work for 16 and 32 bit protected mode. */
139 static long pm_address(u_char FPU_modrm, u_char segment,
140 struct address *addr, long offset)
141 {
142 struct desc_struct descriptor;
143 unsigned long base_address, limit, address, seg_top;
144
145 segment--;
146
147 #ifdef PARANOID
148 /* segment is unsigned, so this also detects if segment was 0: */
149 if (segment > PREFIX_SS_) {
150 EXCEPTION(EX_INTERNAL | 0x132);
151 math_abort(FPU_info, SIGSEGV);
152 }
153 #endif /* PARANOID */
154
155 switch (segment) {
156 /* gs isn't used by the kernel, so it still has its
157 user-space value. */
158 case PREFIX_GS_ - 1:
159 /* N.B. - movl %seg, mem is a 2 byte write regardless of prefix */
160 savesegment(gs, addr->selector);
161 break;
162 default:
163 addr->selector = PM_REG_(segment);
164 }
165
166 descriptor = LDT_DESCRIPTOR(PM_REG_(segment));
167 base_address = SEG_BASE_ADDR(descriptor);
168 address = base_address + offset;
169 limit = base_address
170 + (SEG_LIMIT(descriptor) + 1) * SEG_GRANULARITY(descriptor) - 1;
171 if (limit < base_address)
172 limit = 0xffffffff;
173
174 if (SEG_EXPAND_DOWN(descriptor)) {
175 if (SEG_G_BIT(descriptor))
176 seg_top = 0xffffffff;
177 else {
178 seg_top = base_address + (1 << 20);
179 if (seg_top < base_address)
180 seg_top = 0xffffffff;
181 }
182 access_limit =
183 (address <= limit) || (address >= seg_top) ? 0 :
184 ((seg_top - address) >= 255 ? 255 : seg_top - address);
185 } else {
186 access_limit =
187 (address > limit) || (address < base_address) ? 0 :
188 ((limit - address) >= 254 ? 255 : limit - address + 1);
189 }
190 if (SEG_EXECUTE_ONLY(descriptor) ||
191 (!SEG_WRITE_PERM(descriptor) && (FPU_modrm & FPU_WRITE_BIT))) {
192 access_limit = 0;
193 }
194 return address;
195 }
196
197 /*
198 MOD R/M byte: MOD == 3 has a special use for the FPU
199 SIB byte used iff R/M = 100b
200
201 7 6 5 4 3 2 1 0
202 ..... ......... .........
203 MOD OPCODE(2) R/M
204
205 SIB byte
206
207 7 6 5 4 3 2 1 0
208 ..... ......... .........
209 SS INDEX BASE
210
211 */
212
213 void __user *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip,
214 struct address *addr, fpu_addr_modes addr_modes)
215 {
216 u_char mod;
217 unsigned rm = FPU_modrm & 7;
218 long *cpu_reg_ptr;
219 int address = 0; /* Initialized just to stop compiler warnings. */
220
221 /* Memory accessed via the cs selector is write protected
222 in `non-segmented' 32 bit protected mode. */
223 if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
224 && (addr_modes.override.segment == PREFIX_CS_)) {
225 math_abort(FPU_info, SIGSEGV);
226 }
227
228 addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
229
230 mod = (FPU_modrm >> 6) & 3;
231
232 if (rm == 4 && mod != 3) {
233 address = sib(mod, fpu_eip);
234 } else {
235 cpu_reg_ptr = ®_(rm);
236 switch (mod) {
237 case 0:
238 if (rm == 5) {
239 /* Special case: disp32 */
240 RE_ENTRANT_CHECK_OFF;
241 FPU_code_access_ok(4);
242 FPU_get_user(address,
243 (unsigned long __user
244 *)(*fpu_eip));
245 (*fpu_eip) += 4;
246 RE_ENTRANT_CHECK_ON;
247 addr->offset = address;
248 return (void __user *)address;
249 } else {
250 address = *cpu_reg_ptr; /* Just return the contents
251 of the cpu register */
252 addr->offset = address;
253 return (void __user *)address;
254 }
255 case 1:
256 /* 8 bit signed displacement */
257 RE_ENTRANT_CHECK_OFF;
258 FPU_code_access_ok(1);
259 FPU_get_user(address, (signed char __user *)(*fpu_eip));
260 RE_ENTRANT_CHECK_ON;
261 (*fpu_eip)++;
262 break;
263 case 2:
264 /* 32 bit displacement */
265 RE_ENTRANT_CHECK_OFF;
266 FPU_code_access_ok(4);
267 FPU_get_user(address, (long __user *)(*fpu_eip));
268 (*fpu_eip) += 4;
269 RE_ENTRANT_CHECK_ON;
270 break;
271 case 3:
272 /* Not legal for the FPU */
273 EXCEPTION(EX_Invalid);
274 }
275 address += *cpu_reg_ptr;
276 }
277
278 addr->offset = address;
279
280 switch (addr_modes.default_mode) {
281 case 0:
282 break;
283 case VM86:
284 address += vm86_segment(addr_modes.override.segment, addr);
285 break;
286 case PM16:
287 case SEG32:
288 address = pm_address(FPU_modrm, addr_modes.override.segment,
289 addr, address);
290 break;
291 default:
292 EXCEPTION(EX_INTERNAL | 0x133);
293 }
294
295 return (void __user *)address;
296 }
297
298 void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip,
299 struct address *addr, fpu_addr_modes addr_modes)
300 {
301 u_char mod;
302 unsigned rm = FPU_modrm & 7;
303 int address = 0; /* Default used for mod == 0 */
304
305 /* Memory accessed via the cs selector is write protected
306 in `non-segmented' 32 bit protected mode. */
307 if (!addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT)
308 && (addr_modes.override.segment == PREFIX_CS_)) {
309 math_abort(FPU_info, SIGSEGV);
310 }
311
312 addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */
313
314 mod = (FPU_modrm >> 6) & 3;
315
316 switch (mod) {
317 case 0:
318 if (rm == 6) {
319 /* Special case: disp16 */
320 RE_ENTRANT_CHECK_OFF;
321 FPU_code_access_ok(2);
322 FPU_get_user(address,
323 (unsigned short __user *)(*fpu_eip));
324 (*fpu_eip) += 2;
325 RE_ENTRANT_CHECK_ON;
326 goto add_segment;
327 }
328 break;
329 case 1:
330 /* 8 bit signed displacement */
331 RE_ENTRANT_CHECK_OFF;
332 FPU_code_access_ok(1);
333 FPU_get_user(address, (signed char __user *)(*fpu_eip));
334 RE_ENTRANT_CHECK_ON;
335 (*fpu_eip)++;
336 break;
337 case 2:
338 /* 16 bit displacement */
339 RE_ENTRANT_CHECK_OFF;
340 FPU_code_access_ok(2);
341 FPU_get_user(address, (unsigned short __user *)(*fpu_eip));
342 (*fpu_eip) += 2;
343 RE_ENTRANT_CHECK_ON;
344 break;
345 case 3:
346 /* Not legal for the FPU */
347 EXCEPTION(EX_Invalid);
348 break;
349 }
350 switch (rm) {
351 case 0:
352 address += FPU_info->___ebx + FPU_info->___esi;
353 break;
354 case 1:
355 address += FPU_info->___ebx + FPU_info->___edi;
356 break;
357 case 2:
358 address += FPU_info->___ebp + FPU_info->___esi;
359 if (addr_modes.override.segment == PREFIX_DEFAULT)
360 addr_modes.override.segment = PREFIX_SS_;
361 break;
362 case 3:
363 address += FPU_info->___ebp + FPU_info->___edi;
364 if (addr_modes.override.segment == PREFIX_DEFAULT)
365 addr_modes.override.segment = PREFIX_SS_;
366 break;
367 case 4:
368 address += FPU_info->___esi;
369 break;
370 case 5:
371 address += FPU_info->___edi;
372 break;
373 case 6:
374 address += FPU_info->___ebp;
375 if (addr_modes.override.segment == PREFIX_DEFAULT)
376 addr_modes.override.segment = PREFIX_SS_;
377 break;
378 case 7:
379 address += FPU_info->___ebx;
380 break;
381 }
382
383 add_segment:
384 address &= 0xffff;
385
386 addr->offset = address;
387
388 switch (addr_modes.default_mode) {
389 case 0:
390 break;
391 case VM86:
392 address += vm86_segment(addr_modes.override.segment, addr);
393 break;
394 case PM16:
395 case SEG32:
396 address = pm_address(FPU_modrm, addr_modes.override.segment,
397 addr, address);
398 break;
399 default:
400 EXCEPTION(EX_INTERNAL | 0x131);
401 }
402
403 return (void __user *)address;
404 }
405
|
This page was automatically generated by the
LXR engine.
|