1 // SPDX-License-Identifier: GPL-2.0
2 /*---------------------------------------------------------------------------+
3 | fpu_entry.c |
4 | |
5 | The entry functions for wm-FPU-emu |
6 | |
7 | Copyright (C) 1992,1993,1994,1996,1997 |
8 | W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
9 | E-mail billm@suburbia.net |
10 | |
11 | See the files "README" and "COPYING" for further copyright and warranty |
12 | information. |
13 | |
14 +---------------------------------------------------------------------------*/
15
16 /*---------------------------------------------------------------------------+
17 | Note: |
18 | The file contains code which accesses user memory. |
19 | Emulator static data may change when user memory is accessed, due to |
20 | other processes using the emulator while swapping is in progress. |
21 +---------------------------------------------------------------------------*/
22
23 /*---------------------------------------------------------------------------+
24 | math_emulate(), restore_i387_soft() and save_i387_soft() are the only |
25 | entry points for wm-FPU-emu. |
26 +---------------------------------------------------------------------------*/
27
28 #include <linux/signal.h>
29 #include <linux/regset.h>
30
31 #include <linux/uaccess.h>
32 #include <asm/traps.h>
33 #include <asm/user.h>
34 #include <asm/fpu/api.h>
35 #include <asm/fpu/regset.h>
36
37 #include "fpu_system.h"
38 #include "fpu_emu.h"
39 #include "exception.h"
40 #include "control_w.h"
41 #include "status_w.h"
42
43 #define __BAD__ FPU_illegal /* Illegal on an 80486, causes SIGILL */
44
45 /* fcmovCC and f(u)comi(p) are enabled if CPUID(1).EDX(15) "cmov" is set */
46
47 /* WARNING: "u" entries are not documented by Intel in their 80486 manual
48 and may not work on FPU clones or later Intel FPUs.
49 Changes to support them provided by Linus Torvalds. */
50
51 static FUNC const st_instr_table[64] = {
52 /* Opcode: d8 d9 da db */
53 /* dc dd de df */
54 /* c0..7 */ fadd__, fld_i_, fcmovb, fcmovnb,
55 /* c0..7 */ fadd_i, ffree_, faddp_, ffreep,/*u*/
56 /* c8..f */ fmul__, fxch_i, fcmove, fcmovne,
57 /* c8..f */ fmul_i, fxch_i,/*u*/ fmulp_, fxch_i,/*u*/
58 /* d0..7 */ fcom_st, fp_nop, fcmovbe, fcmovnbe,
59 /* d0..7 */ fcom_st,/*u*/ fst_i_, fcompst,/*u*/ fstp_i,/*u*/
60 /* d8..f */ fcompst, fstp_i,/*u*/ fcmovu, fcmovnu,
61 /* d8..f */ fcompst,/*u*/ fstp_i, fcompp, fstp_i,/*u*/
62 /* e0..7 */ fsub__, FPU_etc, __BAD__, finit_,
63 /* e0..7 */ fsubri, fucom_, fsubrp, fstsw_,
64 /* e8..f */ fsubr_, fconst, fucompp, fucomi_,
65 /* e8..f */ fsub_i, fucomp, fsubp_, fucomip,
66 /* f0..7 */ fdiv__, FPU_triga, __BAD__, fcomi_,
67 /* f0..7 */ fdivri, __BAD__, fdivrp, fcomip,
68 /* f8..f */ fdivr_, FPU_trigb, __BAD__, __BAD__,
69 /* f8..f */ fdiv_i, __BAD__, fdivp_, __BAD__,
70 };
71
72 #define _NONE_ 0 /* Take no special action */
73 #define _REG0_ 1 /* Need to check for not empty st(0) */
74 #define _REGI_ 2 /* Need to check for not empty st(0) and st(rm) */
75 #define _REGi_ 0 /* Uses st(rm) */
76 #define _PUSH_ 3 /* Need to check for space to push onto stack */
77 #define _null_ 4 /* Function illegal or not implemented */
78 #define _REGIi 5 /* Uses st(0) and st(rm), result to st(rm) */
79 #define _REGIp 6 /* Uses st(0) and st(rm), result to st(rm) then pop */
80 #define _REGIc 0 /* Compare st(0) and st(rm) */
81 #define _REGIn 0 /* Uses st(0) and st(rm), but handle checks later */
82
83 static u_char const type_table[64] = {
84 /* Opcode: d8 d9 da db dc dd de df */
85 /* c0..7 */ _REGI_, _NONE_, _REGIn, _REGIn, _REGIi, _REGi_, _REGIp, _REGi_,
86 /* c8..f */ _REGI_, _REGIn, _REGIn, _REGIn, _REGIi, _REGI_, _REGIp, _REGI_,
87 /* d0..7 */ _REGIc, _NONE_, _REGIn, _REGIn, _REGIc, _REG0_, _REGIc, _REG0_,
88 /* d8..f */ _REGIc, _REG0_, _REGIn, _REGIn, _REGIc, _REG0_, _REGIc, _REG0_,
89 /* e0..7 */ _REGI_, _NONE_, _null_, _NONE_, _REGIi, _REGIc, _REGIp, _NONE_,
90 /* e8..f */ _REGI_, _NONE_, _REGIc, _REGIc, _REGIi, _REGIc, _REGIp, _REGIc,
91 /* f0..7 */ _REGI_, _NONE_, _null_, _REGIc, _REGIi, _null_, _REGIp, _REGIc,
92 /* f8..f */ _REGI_, _NONE_, _null_, _null_, _REGIi, _null_, _REGIp, _null_,
93 };
94
95 #ifdef RE_ENTRANT_CHECKING
96 u_char emulating = 0;
97 #endif /* RE_ENTRANT_CHECKING */
98
99 static int valid_prefix(u_char *Byte, u_char __user ** fpu_eip,
100 overrides * override);
101
102 void math_emulate(struct math_emu_info *info)
103 {
104 u_char FPU_modrm, byte1;
105 unsigned short code;
106 fpu_addr_modes addr_modes;
107 int unmasked;
108 FPU_REG loaded_data;
109 FPU_REG *st0_ptr;
110 u_char loaded_tag, st0_tag;
111 void __user *data_address;
112 struct address data_sel_off;
113 struct address entry_sel_off;
114 unsigned long code_base = 0;
115 unsigned long code_limit = 0; /* Initialized to stop compiler warnings */
116 struct desc_struct code_descriptor;
117
118 #ifdef RE_ENTRANT_CHECKING
119 if (emulating) {
120 printk("ERROR: wm-FPU-emu is not RE-ENTRANT!\n");
121 }
122 RE_ENTRANT_CHECK_ON;
123 #endif /* RE_ENTRANT_CHECKING */
124
125 FPU_info = info;
126
127 FPU_ORIG_EIP = FPU_EIP;
128
129 if ((FPU_EFLAGS & 0x00020000) != 0) {
130 /* Virtual 8086 mode */
131 addr_modes.default_mode = VM86;
132 FPU_EIP += code_base = FPU_CS << 4;
133 code_limit = code_base + 0xffff; /* Assumes code_base <= 0xffff0000 */
134 } else if (FPU_CS == __USER_CS && FPU_DS == __USER_DS) {
135 addr_modes.default_mode = 0;
136 } else if (FPU_CS == __KERNEL_CS) {
137 printk("math_emulate: %04x:%08lx\n", FPU_CS, FPU_EIP);
138 panic("Math emulation needed in kernel");
139 } else {
140
141 if ((FPU_CS & 4) != 4) { /* Must be in the LDT */
142 /* Can only handle segmented addressing via the LDT
143 for now, and it must be 16 bit */
144 printk("FPU emulator: Unsupported addressing mode\n");
145 math_abort(FPU_info, SIGILL);
146 }
147
148 code_descriptor = FPU_get_ldt_descriptor(FPU_CS);
149 if (code_descriptor.d) {
150 /* The above test may be wrong, the book is not clear */
151 /* Segmented 32 bit protected mode */
152 addr_modes.default_mode = SEG32;
153 } else {
154 /* 16 bit protected mode */
155 addr_modes.default_mode = PM16;
156 }
157 FPU_EIP += code_base = seg_get_base(&code_descriptor);
158 code_limit = seg_get_limit(&code_descriptor) + 1;
159 code_limit *= seg_get_granularity(&code_descriptor);
160 code_limit += code_base - 1;
161 if (code_limit < code_base)
162 code_limit = 0xffffffff;
163 }
164
165 FPU_lookahead = !(FPU_EFLAGS & X86_EFLAGS_TF);
166
167 if (!valid_prefix(&byte1, (u_char __user **) & FPU_EIP,
168 &addr_modes.override)) {
169 RE_ENTRANT_CHECK_OFF;
170 printk
171 ("FPU emulator: Unknown prefix byte 0x%02x, probably due to\n"
172 "FPU emulator: self-modifying code! (emulation impossible)\n",
173 byte1);
174 RE_ENTRANT_CHECK_ON;
175 EXCEPTION(EX_INTERNAL | 0x126);
176 math_abort(FPU_info, SIGILL);
177 }
178
179 do_another_FPU_instruction:
180
181 no_ip_update = 0;
182
183 FPU_EIP++; /* We have fetched the prefix and first code bytes. */
184
185 if (addr_modes.default_mode) {
186 /* This checks for the minimum instruction bytes.
187 We also need to check any extra (address mode) code access. */
188 if (FPU_EIP > code_limit)
189 math_abort(FPU_info, SIGSEGV);
190 }
191
192 if ((byte1 & 0xf8) != 0xd8) {
193 if (byte1 == FWAIT_OPCODE) {
194 if (partial_status & SW_Summary)
195 goto do_the_FPU_interrupt;
196 else
197 goto FPU_fwait_done;
198 }
199 #ifdef PARANOID
200 EXCEPTION(EX_INTERNAL | 0x128);
201 math_abort(FPU_info, SIGILL);
202 #endif /* PARANOID */
203 }
204
205 RE_ENTRANT_CHECK_OFF;
206 FPU_code_access_ok(1);
207 FPU_get_user(FPU_modrm, (u_char __user *) FPU_EIP);
208 RE_ENTRANT_CHECK_ON;
209 FPU_EIP++;
210
211 if (partial_status & SW_Summary) {
212 /* Ignore the error for now if the current instruction is a no-wait
213 control instruction */
214 /* The 80486 manual contradicts itself on this topic,
215 but a real 80486 uses the following instructions:
216 fninit, fnstenv, fnsave, fnstsw, fnstenv, fnclex.
217 */
218 code = (FPU_modrm << 8) | byte1;
219 if (!((((code & 0xf803) == 0xe003) || /* fnclex, fninit, fnstsw */
220 (((code & 0x3003) == 0x3001) && /* fnsave, fnstcw, fnstenv,
221 fnstsw */
222 ((code & 0xc000) != 0xc000))))) {
223 /*
224 * We need to simulate the action of the kernel to FPU
225 * interrupts here.
226 */
227 do_the_FPU_interrupt:
228
229 FPU_EIP = FPU_ORIG_EIP; /* Point to current FPU instruction. */
230
231 RE_ENTRANT_CHECK_OFF;
232 current->thread.trap_nr = X86_TRAP_MF;
233 current->thread.error_code = 0;
234 send_sig(SIGFPE, current, 1);
235 return;
236 }
237 }
238
239 entry_sel_off.offset = FPU_ORIG_EIP;
240 entry_sel_off.selector = FPU_CS;
241 entry_sel_off.opcode = (byte1 << 8) | FPU_modrm;
242 entry_sel_off.empty = 0;
243
244 FPU_rm = FPU_modrm & 7;
245
246 if (FPU_modrm < 0300) {
247 /* All of these instructions use the mod/rm byte to get a data address */
248
249 if ((addr_modes.default_mode & SIXTEEN)
250 ^ (addr_modes.override.address_size == ADDR_SIZE_PREFIX))
251 data_address =
252 FPU_get_address_16(FPU_modrm, &FPU_EIP,
253 &data_sel_off, addr_modes);
254 else
255 data_address =
256 FPU_get_address(FPU_modrm, &FPU_EIP, &data_sel_off,
257 addr_modes);
258
259 if (addr_modes.default_mode) {
260 if (FPU_EIP - 1 > code_limit)
261 math_abort(FPU_info, SIGSEGV);
262 }
263
264 if (!(byte1 & 1)) {
265 unsigned short status1 = partial_status;
266
267 st0_ptr = &st(0);
268 st0_tag = FPU_gettag0();
269
270 /* Stack underflow has priority */
271 if (NOT_EMPTY_ST0) {
272 if (addr_modes.default_mode & PROTECTED) {
273 /* This table works for 16 and 32 bit protected mode */
274 if (access_limit <
275 data_sizes_16[(byte1 >> 1) & 3])
276 math_abort(FPU_info, SIGSEGV);
277 }
278
279 unmasked = 0; /* Do this here to stop compiler warnings. */
280 switch ((byte1 >> 1) & 3) {
281 case 0:
282 unmasked =
283 FPU_load_single((float __user *)
284 data_address,
285 &loaded_data);
286 loaded_tag = unmasked & 0xff;
287 unmasked &= ~0xff;
288 break;
289 case 1:
290 loaded_tag =
291 FPU_load_int32((long __user *)
292 data_address,
293 &loaded_data);
294 break;
295 case 2:
296 unmasked =
297 FPU_load_double((double __user *)
298 data_address,
299 &loaded_data);
300 loaded_tag = unmasked & 0xff;
301 unmasked &= ~0xff;
302 break;
303 case 3:
304 default: /* Used here to suppress gcc warnings. */
305 loaded_tag =
306 FPU_load_int16((short __user *)
307 data_address,
308 &loaded_data);
309 break;
310 }
311
312 /* No more access to user memory, it is safe
313 to use static data now */
314
315 /* NaN operands have the next priority. */
316 /* We have to delay looking at st(0) until after
317 loading the data, because that data might contain an SNaN */
318 if (((st0_tag == TAG_Special) && isNaN(st0_ptr))
319 || ((loaded_tag == TAG_Special)
320 && isNaN(&loaded_data))) {
321 /* Restore the status word; we might have loaded a
322 denormal. */
323 partial_status = status1;
324 if ((FPU_modrm & 0x30) == 0x10) {
325 /* fcom or fcomp */
326 EXCEPTION(EX_Invalid);
327 setcc(SW_C3 | SW_C2 | SW_C0);
328 if ((FPU_modrm & 0x08)
329 && (control_word &
330 CW_Invalid))
331 FPU_pop(); /* fcomp, masked, so we pop. */
332 } else {
333 if (loaded_tag == TAG_Special)
334 loaded_tag =
335 FPU_Special
336 (&loaded_data);
337 #ifdef PECULIAR_486
338 /* This is not really needed, but gives behaviour
339 identical to an 80486 */
340 if ((FPU_modrm & 0x28) == 0x20)
341 /* fdiv or fsub */
342 real_2op_NaN
343 (&loaded_data,
344 loaded_tag, 0,
345 &loaded_data);
346 else
347 #endif /* PECULIAR_486 */
348 /* fadd, fdivr, fmul, or fsubr */
349 real_2op_NaN
350 (&loaded_data,
351 loaded_tag, 0,
352 st0_ptr);
353 }
354 goto reg_mem_instr_done;
355 }
356
357 if (unmasked && !((FPU_modrm & 0x30) == 0x10)) {
358 /* Is not a comparison instruction. */
359 if ((FPU_modrm & 0x38) == 0x38) {
360 /* fdivr */
361 if ((st0_tag == TAG_Zero) &&
362 ((loaded_tag == TAG_Valid)
363 || (loaded_tag ==
364 TAG_Special
365 &&
366 isdenormal
367 (&loaded_data)))) {
368 if (FPU_divide_by_zero
369 (0,
370 getsign
371 (&loaded_data))
372 < 0) {
373 /* We use the fact here that the unmasked
374 exception in the loaded data was for a
375 denormal operand */
376 /* Restore the state of the denormal op bit */
377 partial_status
378 &=
379 ~SW_Denorm_Op;
380 partial_status
381 |=
382 status1 &
383 SW_Denorm_Op;
384 } else
385 setsign(st0_ptr,
386 getsign
387 (&loaded_data));
388 }
389 }
390 goto reg_mem_instr_done;
391 }
392
393 switch ((FPU_modrm >> 3) & 7) {
394 case 0: /* fadd */
395 clear_C1();
396 FPU_add(&loaded_data, loaded_tag, 0,
397 control_word);
398 break;
399 case 1: /* fmul */
400 clear_C1();
401 FPU_mul(&loaded_data, loaded_tag, 0,
402 control_word);
403 break;
404 case 2: /* fcom */
405 FPU_compare_st_data(&loaded_data,
406 loaded_tag);
407 break;
408 case 3: /* fcomp */
409 if (!FPU_compare_st_data
410 (&loaded_data, loaded_tag)
411 && !unmasked)
412 FPU_pop();
413 break;
414 case 4: /* fsub */
415 clear_C1();
416 FPU_sub(LOADED | loaded_tag,
417 (int)&loaded_data,
418 control_word);
419 break;
420 case 5: /* fsubr */
421 clear_C1();
422 FPU_sub(REV | LOADED | loaded_tag,
423 (int)&loaded_data,
424 control_word);
425 break;
426 case 6: /* fdiv */
427 clear_C1();
428 FPU_div(LOADED | loaded_tag,
429 (int)&loaded_data,
430 control_word);
431 break;
432 case 7: /* fdivr */
433 clear_C1();
434 if (st0_tag == TAG_Zero)
435 partial_status = status1; /* Undo any denorm tag,
436 zero-divide has priority. */
437 FPU_div(REV | LOADED | loaded_tag,
438 (int)&loaded_data,
439 control_word);
440 break;
441 }
442 } else {
443 if ((FPU_modrm & 0x30) == 0x10) {
444 /* The instruction is fcom or fcomp */
445 EXCEPTION(EX_StackUnder);
446 setcc(SW_C3 | SW_C2 | SW_C0);
447 if ((FPU_modrm & 0x08)
448 && (control_word & CW_Invalid))
449 FPU_pop(); /* fcomp */
450 } else
451 FPU_stack_underflow();
452 }
453 reg_mem_instr_done:
454 operand_address = data_sel_off;
455 } else {
456 if (!(no_ip_update =
457 FPU_load_store(((FPU_modrm & 0x38) | (byte1 & 6))
458 >> 1, addr_modes, data_address))) {
459 operand_address = data_sel_off;
460 }
461 }
462
463 } else {
464 /* None of these instructions access user memory */
465 u_char instr_index = (FPU_modrm & 0x38) | (byte1 & 7);
466
467 #ifdef PECULIAR_486
468 /* This is supposed to be undefined, but a real 80486 seems
469 to do this: */
470 operand_address.offset = 0;
471 operand_address.selector = FPU_DS;
472 #endif /* PECULIAR_486 */
473
474 st0_ptr = &st(0);
475 st0_tag = FPU_gettag0();
476 switch (type_table[(int)instr_index]) {
477 case _NONE_: /* also _REGIc: _REGIn */
478 break;
479 case _REG0_:
480 if (!NOT_EMPTY_ST0) {
481 FPU_stack_underflow();
482 goto FPU_instruction_done;
483 }
484 break;
485 case _REGIi:
486 if (!NOT_EMPTY_ST0 || !NOT_EMPTY(FPU_rm)) {
487 FPU_stack_underflow_i(FPU_rm);
488 goto FPU_instruction_done;
489 }
490 break;
491 case _REGIp:
492 if (!NOT_EMPTY_ST0 || !NOT_EMPTY(FPU_rm)) {
493 FPU_stack_underflow_pop(FPU_rm);
494 goto FPU_instruction_done;
495 }
496 break;
497 case _REGI_:
498 if (!NOT_EMPTY_ST0 || !NOT_EMPTY(FPU_rm)) {
499 FPU_stack_underflow();
500 goto FPU_instruction_done;
501 }
502 break;
503 case _PUSH_: /* Only used by the fld st(i) instruction */
504 break;
505 case _null_:
506 FPU_illegal();
507 goto FPU_instruction_done;
508 default:
509 EXCEPTION(EX_INTERNAL | 0x111);
510 goto FPU_instruction_done;
511 }
512 (*st_instr_table[(int)instr_index]) ();
513
514 FPU_instruction_done:
515 ;
516 }
517
518 if (!no_ip_update)
519 instruction_address = entry_sel_off;
520
521 FPU_fwait_done:
522
523 #ifdef DEBUG
524 RE_ENTRANT_CHECK_OFF;
525 FPU_printall();
526 RE_ENTRANT_CHECK_ON;
527 #endif /* DEBUG */
528
529 if (FPU_lookahead && !need_resched()) {
530 FPU_ORIG_EIP = FPU_EIP - code_base;
531 if (valid_prefix(&byte1, (u_char __user **) & FPU_EIP,
532 &addr_modes.override))
533 goto do_another_FPU_instruction;
534 }
535
536 if (addr_modes.default_mode)
537 FPU_EIP -= code_base;
538
539 RE_ENTRANT_CHECK_OFF;
540 }
541
542 /* Support for prefix bytes is not yet complete. To properly handle
543 all prefix bytes, further changes are needed in the emulator code
544 which accesses user address space. Access to separate segments is
545 important for msdos emulation. */
546 static int valid_prefix(u_char *Byte, u_char __user **fpu_eip,
547 overrides * override)
548 {
549 u_char byte;
550 u_char __user *ip = *fpu_eip;
551
552 *override = (overrides) {
553 0, 0, PREFIX_DEFAULT}; /* defaults */
554
555 RE_ENTRANT_CHECK_OFF;
556 FPU_code_access_ok(1);
557 FPU_get_user(byte, ip);
558 RE_ENTRANT_CHECK_ON;
559
560 while (1) {
561 switch (byte) {
562 case ADDR_SIZE_PREFIX:
563 override->address_size = ADDR_SIZE_PREFIX;
564 goto do_next_byte;
565
566 case OP_SIZE_PREFIX:
567 override->operand_size = OP_SIZE_PREFIX;
568 goto do_next_byte;
569
570 case PREFIX_CS:
571 override->segment = PREFIX_CS_;
572 goto do_next_byte;
573 case PREFIX_ES:
574 override->segment = PREFIX_ES_;
575 goto do_next_byte;
576 case PREFIX_SS:
577 override->segment = PREFIX_SS_;
578 goto do_next_byte;
579 case PREFIX_FS:
580 override->segment = PREFIX_FS_;
581 goto do_next_byte;
582 case PREFIX_GS:
583 override->segment = PREFIX_GS_;
584 goto do_next_byte;
585 case PREFIX_DS:
586 override->segment = PREFIX_DS_;
587 goto do_next_byte;
588
589 /* lock is not a valid prefix for FPU instructions,
590 let the cpu handle it to generate a SIGILL. */
591 /* case PREFIX_LOCK: */
592
593 /* rep.. prefixes have no meaning for FPU instructions */
594 case PREFIX_REPE:
595 case PREFIX_REPNE:
596
597 do_next_byte:
598 ip++;
599 RE_ENTRANT_CHECK_OFF;
600 FPU_code_access_ok(1);
601 FPU_get_user(byte, ip);
602 RE_ENTRANT_CHECK_ON;
603 break;
604 case FWAIT_OPCODE:
605 *Byte = byte;
606 return 1;
607 default:
608 if ((byte & 0xf8) == 0xd8) {
609 *Byte = byte;
610 *fpu_eip = ip;
611 return 1;
612 } else {
613 /* Not a valid sequence of prefix bytes followed by
614 an FPU instruction. */
615 *Byte = byte; /* Needed for error message. */
616 return 0;
617 }
618 }
619 }
620 }
621
622 void math_abort(struct math_emu_info *info, unsigned int signal)
623 {
624 FPU_EIP = FPU_ORIG_EIP;
625 current->thread.trap_nr = X86_TRAP_MF;
626 current->thread.error_code = 0;
627 send_sig(signal, current, 1);
628 RE_ENTRANT_CHECK_OFF;
629 __asm__("movl %0,%%esp ; ret": :"g"(((long)info) - 4));
630 #ifdef PARANOID
631 printk("ERROR: wm-FPU-emu math_abort failed!\n");
632 #endif /* PARANOID */
633 }
634
635 #define S387 ((struct swregs_state *)s387)
636 #define sstatus_word() \
637 ((S387->swd & ~SW_Top & 0xffff) | ((S387->ftop << SW_Top_Shift) & SW_Top))
638
639 int fpregs_soft_set(struct task_struct *target,
640 const struct user_regset *regset,
641 unsigned int pos, unsigned int count,
642 const void *kbuf, const void __user *ubuf)
643 {
644 struct swregs_state *s387 = &target->thread.fpu.fpstate->regs.soft;
645 void *space = s387->st_space;
646 int ret;
647 int offset, other, i, tags, regnr, tag, newtop;
648
649 RE_ENTRANT_CHECK_OFF;
650 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, s387, 0,
651 offsetof(struct swregs_state, st_space));
652 RE_ENTRANT_CHECK_ON;
653
654 if (ret)
655 return ret;
656
657 S387->ftop = (S387->swd >> SW_Top_Shift) & 7;
658 offset = (S387->ftop & 7) * 10;
659 other = 80 - offset;
660
661 RE_ENTRANT_CHECK_OFF;
662
663 /* Copy all registers in stack order. */
664 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
665 space + offset, 0, other);
666 if (!ret && offset)
667 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
668 space, 0, offset);
669
670 RE_ENTRANT_CHECK_ON;
671
672 /* The tags may need to be corrected now. */
673 tags = S387->twd;
674 newtop = S387->ftop;
675 for (i = 0; i < 8; i++) {
676 regnr = (i + newtop) & 7;
677 if (((tags >> ((regnr & 7) * 2)) & 3) != TAG_Empty) {
678 /* The loaded data over-rides all other cases. */
679 tag =
680 FPU_tagof((FPU_REG *) ((u_char *) S387->st_space +
681 10 * regnr));
682 tags &= ~(3 << (regnr * 2));
683 tags |= (tag & 3) << (regnr * 2);
684 }
685 }
686 S387->twd = tags;
687
688 return ret;
689 }
690
691 int fpregs_soft_get(struct task_struct *target,
692 const struct user_regset *regset,
693 struct membuf to)
694 {
695 struct swregs_state *s387 = &target->thread.fpu.fpstate->regs.soft;
696 const void *space = s387->st_space;
697 int offset = (S387->ftop & 7) * 10, other = 80 - offset;
698
699 RE_ENTRANT_CHECK_OFF;
700
701 #ifdef PECULIAR_486
702 S387->cwd &= ~0xe080;
703 /* An 80486 sets nearly all of the reserved bits to 1. */
704 S387->cwd |= 0xffff0040;
705 S387->swd = sstatus_word() | 0xffff0000;
706 S387->twd |= 0xffff0000;
707 S387->fcs &= ~0xf8000000;
708 S387->fos |= 0xffff0000;
709 #endif /* PECULIAR_486 */
710
711 membuf_write(&to, s387, offsetof(struct swregs_state, st_space));
712 membuf_write(&to, space + offset, other);
713 membuf_write(&to, space, offset);
714
715 RE_ENTRANT_CHECK_ON;
716
717 return 0;
718 }
719
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