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allow coexistance of N build and AC build.
[tomato.git] / release / src-rt-6.x / linux / linux-2.6 / arch / i386 / math-emu / get_address.c
blob2e2c51a8bd3ae6d921167607977d9f25d2f75ae0
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
59 /* This dummy, gs is not saved on the stack. */
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),
66 offsetof(struct info,___fs),
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;
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 {
171 /* gs isn't used by the kernel, so it still has its
172 user-space value. */
173 case PREFIX_GS_-1:
174 /* N.B. - movl %seg, mem is a 2 byte write regardless of prefix */
175 savesegment(gs, addr->selector);
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 }
Tomato firmware and modifications.