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1da177e4 LT |
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 | ||
21 | #include <linux/stddef.h> | |
22 | ||
23 | #include <asm/uaccess.h> | |
24 | #include <asm/desc.h> | |
25 | ||
26 | #include "fpu_system.h" | |
27 | #include "exception.h" | |
28 | #include "fpu_emu.h" | |
29 | ||
30 | ||
31 | #define FPU_WRITE_BIT 0x10 | |
32 | ||
33 | static int reg_offset[] = { | |
34 | offsetof(struct info,___eax), | |
35 | offsetof(struct info,___ecx), | |
36 | offsetof(struct info,___edx), | |
37 | offsetof(struct info,___ebx), | |
38 | offsetof(struct info,___esp), | |
39 | offsetof(struct info,___ebp), | |
40 | offsetof(struct info,___esi), | |
41 | offsetof(struct info,___edi) | |
42 | }; | |
43 | ||
44 | #define REG_(x) (*(long *)(reg_offset[(x)]+(u_char *) FPU_info)) | |
45 | ||
46 | static int reg_offset_vm86[] = { | |
47 | offsetof(struct info,___cs), | |
48 | offsetof(struct info,___vm86_ds), | |
49 | offsetof(struct info,___vm86_es), | |
50 | offsetof(struct info,___vm86_fs), | |
51 | offsetof(struct info,___vm86_gs), | |
52 | offsetof(struct info,___ss), | |
53 | offsetof(struct info,___vm86_ds) | |
54 | }; | |
55 | ||
56 | #define VM86_REG_(x) (*(unsigned short *) \ | |
57 | (reg_offset_vm86[((unsigned)x)]+(u_char *) FPU_info)) | |
58 | ||
464d1a78 | 59 | /* This dummy, gs is not saved on the stack. */ |
1da177e4 LT |
60 | #define ___GS ___ds |
61 | ||
62 | static int reg_offset_pm[] = { | |
63 | offsetof(struct info,___cs), | |
64 | offsetof(struct info,___ds), | |
65 | offsetof(struct info,___es), | |
464d1a78 | 66 | offsetof(struct info,___fs), |
1da177e4 LT |
67 | offsetof(struct info,___GS), |
68 | offsetof(struct info,___ss), | |
69 | offsetof(struct info,___ds) | |
70 | }; | |
71 | ||
72 | #define PM_REG_(x) (*(unsigned short *) \ | |
73 | (reg_offset_pm[((unsigned)x)]+(u_char *) FPU_info)) | |
74 | ||
75 | ||
76 | /* Decode the SIB byte. This function assumes mod != 0 */ | |
77 | static int sib(int mod, unsigned long *fpu_eip) | |
78 | { | |
79 | u_char ss,index,base; | |
80 | long offset; | |
81 | ||
82 | RE_ENTRANT_CHECK_OFF; | |
83 | FPU_code_access_ok(1); | |
84 | FPU_get_user(base, (u_char __user *) (*fpu_eip)); /* The SIB byte */ | |
85 | RE_ENTRANT_CHECK_ON; | |
86 | (*fpu_eip)++; | |
87 | ss = base >> 6; | |
88 | index = (base >> 3) & 7; | |
89 | base &= 7; | |
90 | ||
91 | if ((mod == 0) && (base == 5)) | |
92 | offset = 0; /* No base register */ | |
93 | else | |
94 | offset = REG_(base); | |
95 | ||
96 | if (index == 4) | |
97 | { | |
98 | /* No index register */ | |
99 | /* A non-zero ss is illegal */ | |
100 | if ( ss ) | |
101 | EXCEPTION(EX_Invalid); | |
102 | } | |
103 | else | |
104 | { | |
105 | offset += (REG_(index)) << ss; | |
106 | } | |
107 | ||
108 | if (mod == 1) | |
109 | { | |
110 | /* 8 bit signed displacement */ | |
111 | long displacement; | |
112 | RE_ENTRANT_CHECK_OFF; | |
113 | FPU_code_access_ok(1); | |
114 | FPU_get_user(displacement, (signed char __user *) (*fpu_eip)); | |
115 | offset += displacement; | |
116 | RE_ENTRANT_CHECK_ON; | |
117 | (*fpu_eip)++; | |
118 | } | |
119 | else if (mod == 2 || base == 5) /* The second condition also has mod==0 */ | |
120 | { | |
121 | /* 32 bit displacement */ | |
122 | long displacement; | |
123 | RE_ENTRANT_CHECK_OFF; | |
124 | FPU_code_access_ok(4); | |
125 | FPU_get_user(displacement, (long __user *) (*fpu_eip)); | |
126 | offset += displacement; | |
127 | RE_ENTRANT_CHECK_ON; | |
128 | (*fpu_eip) += 4; | |
129 | } | |
130 | ||
131 | return offset; | |
132 | } | |
133 | ||
134 | ||
135 | static unsigned long vm86_segment(u_char segment, | |
136 | struct address *addr) | |
137 | { | |
138 | segment--; | |
139 | #ifdef PARANOID | |
140 | if ( segment > PREFIX_SS_ ) | |
141 | { | |
142 | EXCEPTION(EX_INTERNAL|0x130); | |
143 | math_abort(FPU_info,SIGSEGV); | |
144 | } | |
145 | #endif /* PARANOID */ | |
146 | addr->selector = VM86_REG_(segment); | |
147 | return (unsigned long)VM86_REG_(segment) << 4; | |
148 | } | |
149 | ||
150 | ||
151 | /* This should work for 16 and 32 bit protected mode. */ | |
152 | static long pm_address(u_char FPU_modrm, u_char segment, | |
153 | struct address *addr, long offset) | |
154 | { | |
155 | struct desc_struct descriptor; | |
156 | unsigned long base_address, limit, address, seg_top; | |
1da177e4 LT |
157 | |
158 | segment--; | |
159 | ||
160 | #ifdef PARANOID | |
161 | /* segment is unsigned, so this also detects if segment was 0: */ | |
162 | if ( segment > PREFIX_SS_ ) | |
163 | { | |
164 | EXCEPTION(EX_INTERNAL|0x132); | |
165 | math_abort(FPU_info,SIGSEGV); | |
166 | } | |
167 | #endif /* PARANOID */ | |
168 | ||
169 | switch ( segment ) | |
170 | { | |
464d1a78 JF |
171 | /* gs isn't used by the kernel, so it still has its |
172 | user-space value. */ | |
1da177e4 | 173 | case PREFIX_GS_-1: |
464d1a78 | 174 | /* N.B. - movl %seg, mem is a 2 byte write regardless of prefix */ |
4d37e7e3 | 175 | savesegment(gs, addr->selector); |
1da177e4 LT |
176 | break; |
177 | default: | |
178 | addr->selector = PM_REG_(segment); | |
179 | } | |
180 | ||
181 | descriptor = LDT_DESCRIPTOR(PM_REG_(segment)); | |
182 | base_address = SEG_BASE_ADDR(descriptor); | |
183 | address = base_address + offset; | |
184 | limit = base_address | |
185 | + (SEG_LIMIT(descriptor)+1) * SEG_GRANULARITY(descriptor) - 1; | |
186 | if ( limit < base_address ) limit = 0xffffffff; | |
187 | ||
188 | if ( SEG_EXPAND_DOWN(descriptor) ) | |
189 | { | |
190 | if ( SEG_G_BIT(descriptor) ) | |
191 | seg_top = 0xffffffff; | |
192 | else | |
193 | { | |
194 | seg_top = base_address + (1 << 20); | |
195 | if ( seg_top < base_address ) seg_top = 0xffffffff; | |
196 | } | |
197 | access_limit = | |
198 | (address <= limit) || (address >= seg_top) ? 0 : | |
199 | ((seg_top-address) >= 255 ? 255 : seg_top-address); | |
200 | } | |
201 | else | |
202 | { | |
203 | access_limit = | |
204 | (address > limit) || (address < base_address) ? 0 : | |
205 | ((limit-address) >= 254 ? 255 : limit-address+1); | |
206 | } | |
207 | if ( SEG_EXECUTE_ONLY(descriptor) || | |
208 | (!SEG_WRITE_PERM(descriptor) && (FPU_modrm & FPU_WRITE_BIT)) ) | |
209 | { | |
210 | access_limit = 0; | |
211 | } | |
212 | return address; | |
213 | } | |
214 | ||
215 | ||
216 | /* | |
217 | MOD R/M byte: MOD == 3 has a special use for the FPU | |
218 | SIB byte used iff R/M = 100b | |
219 | ||
220 | 7 6 5 4 3 2 1 0 | |
221 | ..... ......... ......... | |
222 | MOD OPCODE(2) R/M | |
223 | ||
224 | ||
225 | SIB byte | |
226 | ||
227 | 7 6 5 4 3 2 1 0 | |
228 | ..... ......... ......... | |
229 | SS INDEX BASE | |
230 | ||
231 | */ | |
232 | ||
233 | void __user *FPU_get_address(u_char FPU_modrm, unsigned long *fpu_eip, | |
234 | struct address *addr, | |
235 | fpu_addr_modes addr_modes) | |
236 | { | |
237 | u_char mod; | |
238 | unsigned rm = FPU_modrm & 7; | |
239 | long *cpu_reg_ptr; | |
240 | int address = 0; /* Initialized just to stop compiler warnings. */ | |
241 | ||
242 | /* Memory accessed via the cs selector is write protected | |
243 | in `non-segmented' 32 bit protected mode. */ | |
244 | if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) | |
245 | && (addr_modes.override.segment == PREFIX_CS_) ) | |
246 | { | |
247 | math_abort(FPU_info,SIGSEGV); | |
248 | } | |
249 | ||
250 | addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ | |
251 | ||
252 | mod = (FPU_modrm >> 6) & 3; | |
253 | ||
254 | if (rm == 4 && mod != 3) | |
255 | { | |
256 | address = sib(mod, fpu_eip); | |
257 | } | |
258 | else | |
259 | { | |
260 | cpu_reg_ptr = & REG_(rm); | |
261 | switch (mod) | |
262 | { | |
263 | case 0: | |
264 | if (rm == 5) | |
265 | { | |
266 | /* Special case: disp32 */ | |
267 | RE_ENTRANT_CHECK_OFF; | |
268 | FPU_code_access_ok(4); | |
269 | FPU_get_user(address, (unsigned long __user *) (*fpu_eip)); | |
270 | (*fpu_eip) += 4; | |
271 | RE_ENTRANT_CHECK_ON; | |
272 | addr->offset = address; | |
273 | return (void __user *) address; | |
274 | } | |
275 | else | |
276 | { | |
277 | address = *cpu_reg_ptr; /* Just return the contents | |
278 | of the cpu register */ | |
279 | addr->offset = address; | |
280 | return (void __user *) address; | |
281 | } | |
282 | case 1: | |
283 | /* 8 bit signed displacement */ | |
284 | RE_ENTRANT_CHECK_OFF; | |
285 | FPU_code_access_ok(1); | |
286 | FPU_get_user(address, (signed char __user *) (*fpu_eip)); | |
287 | RE_ENTRANT_CHECK_ON; | |
288 | (*fpu_eip)++; | |
289 | break; | |
290 | case 2: | |
291 | /* 32 bit displacement */ | |
292 | RE_ENTRANT_CHECK_OFF; | |
293 | FPU_code_access_ok(4); | |
294 | FPU_get_user(address, (long __user *) (*fpu_eip)); | |
295 | (*fpu_eip) += 4; | |
296 | RE_ENTRANT_CHECK_ON; | |
297 | break; | |
298 | case 3: | |
299 | /* Not legal for the FPU */ | |
300 | EXCEPTION(EX_Invalid); | |
301 | } | |
302 | address += *cpu_reg_ptr; | |
303 | } | |
304 | ||
305 | addr->offset = address; | |
306 | ||
307 | switch ( addr_modes.default_mode ) | |
308 | { | |
309 | case 0: | |
310 | break; | |
311 | case VM86: | |
312 | address += vm86_segment(addr_modes.override.segment, addr); | |
313 | break; | |
314 | case PM16: | |
315 | case SEG32: | |
316 | address = pm_address(FPU_modrm, addr_modes.override.segment, | |
317 | addr, address); | |
318 | break; | |
319 | default: | |
320 | EXCEPTION(EX_INTERNAL|0x133); | |
321 | } | |
322 | ||
323 | return (void __user *)address; | |
324 | } | |
325 | ||
326 | ||
327 | void __user *FPU_get_address_16(u_char FPU_modrm, unsigned long *fpu_eip, | |
328 | struct address *addr, | |
329 | fpu_addr_modes addr_modes) | |
330 | { | |
331 | u_char mod; | |
332 | unsigned rm = FPU_modrm & 7; | |
333 | int address = 0; /* Default used for mod == 0 */ | |
334 | ||
335 | /* Memory accessed via the cs selector is write protected | |
336 | in `non-segmented' 32 bit protected mode. */ | |
337 | if ( !addr_modes.default_mode && (FPU_modrm & FPU_WRITE_BIT) | |
338 | && (addr_modes.override.segment == PREFIX_CS_) ) | |
339 | { | |
340 | math_abort(FPU_info,SIGSEGV); | |
341 | } | |
342 | ||
343 | addr->selector = FPU_DS; /* Default, for 32 bit non-segmented mode. */ | |
344 | ||
345 | mod = (FPU_modrm >> 6) & 3; | |
346 | ||
347 | switch (mod) | |
348 | { | |
349 | case 0: | |
350 | if (rm == 6) | |
351 | { | |
352 | /* Special case: disp16 */ | |
353 | RE_ENTRANT_CHECK_OFF; | |
354 | FPU_code_access_ok(2); | |
355 | FPU_get_user(address, (unsigned short __user *) (*fpu_eip)); | |
356 | (*fpu_eip) += 2; | |
357 | RE_ENTRANT_CHECK_ON; | |
358 | goto add_segment; | |
359 | } | |
360 | break; | |
361 | case 1: | |
362 | /* 8 bit signed displacement */ | |
363 | RE_ENTRANT_CHECK_OFF; | |
364 | FPU_code_access_ok(1); | |
365 | FPU_get_user(address, (signed char __user *) (*fpu_eip)); | |
366 | RE_ENTRANT_CHECK_ON; | |
367 | (*fpu_eip)++; | |
368 | break; | |
369 | case 2: | |
370 | /* 16 bit displacement */ | |
371 | RE_ENTRANT_CHECK_OFF; | |
372 | FPU_code_access_ok(2); | |
373 | FPU_get_user(address, (unsigned short __user *) (*fpu_eip)); | |
374 | (*fpu_eip) += 2; | |
375 | RE_ENTRANT_CHECK_ON; | |
376 | break; | |
377 | case 3: | |
378 | /* Not legal for the FPU */ | |
379 | EXCEPTION(EX_Invalid); | |
380 | break; | |
381 | } | |
382 | switch ( rm ) | |
383 | { | |
384 | case 0: | |
385 | address += FPU_info->___ebx + FPU_info->___esi; | |
386 | break; | |
387 | case 1: | |
388 | address += FPU_info->___ebx + FPU_info->___edi; | |
389 | break; | |
390 | case 2: | |
391 | address += FPU_info->___ebp + FPU_info->___esi; | |
392 | if ( addr_modes.override.segment == PREFIX_DEFAULT ) | |
393 | addr_modes.override.segment = PREFIX_SS_; | |
394 | break; | |
395 | case 3: | |
396 | address += FPU_info->___ebp + FPU_info->___edi; | |
397 | if ( addr_modes.override.segment == PREFIX_DEFAULT ) | |
398 | addr_modes.override.segment = PREFIX_SS_; | |
399 | break; | |
400 | case 4: | |
401 | address += FPU_info->___esi; | |
402 | break; | |
403 | case 5: | |
404 | address += FPU_info->___edi; | |
405 | break; | |
406 | case 6: | |
407 | address += FPU_info->___ebp; | |
408 | if ( addr_modes.override.segment == PREFIX_DEFAULT ) | |
409 | addr_modes.override.segment = PREFIX_SS_; | |
410 | break; | |
411 | case 7: | |
412 | address += FPU_info->___ebx; | |
413 | break; | |
414 | } | |
415 | ||
416 | add_segment: | |
417 | address &= 0xffff; | |
418 | ||
419 | addr->offset = address; | |
420 | ||
421 | switch ( addr_modes.default_mode ) | |
422 | { | |
423 | case 0: | |
424 | break; | |
425 | case VM86: | |
426 | address += vm86_segment(addr_modes.override.segment, addr); | |
427 | break; | |
428 | case PM16: | |
429 | case SEG32: | |
430 | address = pm_address(FPU_modrm, addr_modes.override.segment, | |
431 | addr, address); | |
432 | break; | |
433 | default: | |
434 | EXCEPTION(EX_INTERNAL|0x131); | |
435 | } | |
436 | ||
437 | return (void __user *)address ; | |
438 | } |