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blk: rq_data_dir() should not return a boolean
[cris-mirror.git] / arch / sh / kernel / cpu / sh2a / fpu.c
blob98bbaa447c93400363b9ed1e5b3739473598bfec
1 /*
2 * Save/restore floating point context for signal handlers.
3 *
4 * Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * FIXME! These routines can be optimized in big endian case.
11 */
12 #include <linux/sched.h>
13 #include <linux/signal.h>
14 #include <asm/processor.h>
15 #include <asm/io.h>
16 #include <asm/fpu.h>
17 #include <asm/traps.h>
18
19 /* The PR (precision) bit in the FP Status Register must be clear when
20 * an frchg instruction is executed, otherwise the instruction is undefined.
21 * Executing frchg with PR set causes a trap on some SH4 implementations.
22 */
23
24 #define FPSCR_RCHG 0x00000000
25
26
27 /*
28 * Save FPU registers onto task structure.
29 */
30 void save_fpu(struct task_struct *tsk)
31 {
32 unsigned long dummy;
33
34 enable_fpu();
35 asm volatile("sts.l fpul, @-%0\n\t"
36 "sts.l fpscr, @-%0\n\t"
37 "fmov.s fr15, @-%0\n\t"
38 "fmov.s fr14, @-%0\n\t"
39 "fmov.s fr13, @-%0\n\t"
40 "fmov.s fr12, @-%0\n\t"
41 "fmov.s fr11, @-%0\n\t"
42 "fmov.s fr10, @-%0\n\t"
43 "fmov.s fr9, @-%0\n\t"
44 "fmov.s fr8, @-%0\n\t"
45 "fmov.s fr7, @-%0\n\t"
46 "fmov.s fr6, @-%0\n\t"
47 "fmov.s fr5, @-%0\n\t"
48 "fmov.s fr4, @-%0\n\t"
49 "fmov.s fr3, @-%0\n\t"
50 "fmov.s fr2, @-%0\n\t"
51 "fmov.s fr1, @-%0\n\t"
52 "fmov.s fr0, @-%0\n\t"
53 "lds %3, fpscr\n\t"
54 : "=r" (dummy)
55 : "0" ((char *)(&tsk->thread.xstate->hardfpu.status)),
56 "r" (FPSCR_RCHG),
57 "r" (FPSCR_INIT)
58 : "memory");
59
60 disable_fpu();
61 }
62
63 void restore_fpu(struct task_struct *tsk)
64 {
65 unsigned long dummy;
66
67 enable_fpu();
68 asm volatile("fmov.s @%0+, fr0\n\t"
69 "fmov.s @%0+, fr1\n\t"
70 "fmov.s @%0+, fr2\n\t"
71 "fmov.s @%0+, fr3\n\t"
72 "fmov.s @%0+, fr4\n\t"
73 "fmov.s @%0+, fr5\n\t"
74 "fmov.s @%0+, fr6\n\t"
75 "fmov.s @%0+, fr7\n\t"
76 "fmov.s @%0+, fr8\n\t"
77 "fmov.s @%0+, fr9\n\t"
78 "fmov.s @%0+, fr10\n\t"
79 "fmov.s @%0+, fr11\n\t"
80 "fmov.s @%0+, fr12\n\t"
81 "fmov.s @%0+, fr13\n\t"
82 "fmov.s @%0+, fr14\n\t"
83 "fmov.s @%0+, fr15\n\t"
84 "lds.l @%0+, fpscr\n\t"
85 "lds.l @%0+, fpul\n\t"
86 : "=r" (dummy)
87 : "0" (tsk->thread.xstate), "r" (FPSCR_RCHG)
88 : "memory");
89 disable_fpu();
90 }
91
92 /*
93 * Emulate arithmetic ops on denormalized number for some FPU insns.
94 */
95
96 /* denormalized float * float */
97 static int denormal_mulf(int hx, int hy)
98 {
99 unsigned int ix, iy;
100 unsigned long long m, n;
101 int exp, w;
102
103 ix = hx & 0x7fffffff;
104 iy = hy & 0x7fffffff;
105 if (iy < 0x00800000 || ix == 0)
106 return ((hx ^ hy) & 0x80000000);
107
108 exp = (iy & 0x7f800000) >> 23;
109 ix &= 0x007fffff;
110 iy = (iy & 0x007fffff) | 0x00800000;
111 m = (unsigned long long)ix * iy;
112 n = m;
113 w = -1;
114 while (n) { n >>= 1; w++; }
115
116 /* FIXME: use guard bits */
117 exp += w - 126 - 46;
118 if (exp > 0)
119 ix = ((int) (m >> (w - 23)) & 0x007fffff) | (exp << 23);
120 else if (exp + 22 >= 0)
121 ix = (int) (m >> (w - 22 - exp)) & 0x007fffff;
122 else
123 ix = 0;
124
125 ix |= (hx ^ hy) & 0x80000000;
126 return ix;
127 }
128
129 /* denormalized double * double */
130 static void mult64(unsigned long long x, unsigned long long y,
131 unsigned long long *highp, unsigned long long *lowp)
132 {
133 unsigned long long sub0, sub1, sub2, sub3;
134 unsigned long long high, low;
135
136 sub0 = (x >> 32) * (unsigned long) (y >> 32);
137 sub1 = (x & 0xffffffffLL) * (unsigned long) (y >> 32);
138 sub2 = (x >> 32) * (unsigned long) (y & 0xffffffffLL);
139 sub3 = (x & 0xffffffffLL) * (unsigned long) (y & 0xffffffffLL);
140 low = sub3;
141 high = 0LL;
142 sub3 += (sub1 << 32);
143 if (low > sub3)
144 high++;
145 low = sub3;
146 sub3 += (sub2 << 32);
147 if (low > sub3)
148 high++;
149 low = sub3;
150 high += (sub1 >> 32) + (sub2 >> 32);
151 high += sub0;
152 *lowp = low;
153 *highp = high;
154 }
155
156 static inline long long rshift64(unsigned long long mh,
157 unsigned long long ml, int n)
158 {
159 if (n >= 64)
160 return mh >> (n - 64);
161 return (mh << (64 - n)) | (ml >> n);
162 }
163
164 static long long denormal_muld(long long hx, long long hy)
165 {
166 unsigned long long ix, iy;
167 unsigned long long mh, ml, nh, nl;
168 int exp, w;
169
170 ix = hx & 0x7fffffffffffffffLL;
171 iy = hy & 0x7fffffffffffffffLL;
172 if (iy < 0x0010000000000000LL || ix == 0)
173 return ((hx ^ hy) & 0x8000000000000000LL);
174
175 exp = (iy & 0x7ff0000000000000LL) >> 52;
176 ix &= 0x000fffffffffffffLL;
177 iy = (iy & 0x000fffffffffffffLL) | 0x0010000000000000LL;
178 mult64(ix, iy, &mh, &ml);
179 nh = mh;
180 nl = ml;
181 w = -1;
182 if (nh) {
183 while (nh) { nh >>= 1; w++;}
184 w += 64;
185 } else
186 while (nl) { nl >>= 1; w++;}
187
188 /* FIXME: use guard bits */
189 exp += w - 1022 - 52 * 2;
190 if (exp > 0)
191 ix = (rshift64(mh, ml, w - 52) & 0x000fffffffffffffLL)
192 | ((long long)exp << 52);
193 else if (exp + 51 >= 0)
194 ix = rshift64(mh, ml, w - 51 - exp) & 0x000fffffffffffffLL;
195 else
196 ix = 0;
197
198 ix |= (hx ^ hy) & 0x8000000000000000LL;
199 return ix;
200 }
201
202 /* ix - iy where iy: denormal and ix, iy >= 0 */
203 static int denormal_subf1(unsigned int ix, unsigned int iy)
204 {
205 int frac;
206 int exp;
207
208 if (ix < 0x00800000)
209 return ix - iy;
210
211 exp = (ix & 0x7f800000) >> 23;
212 if (exp - 1 > 31)
213 return ix;
214 iy >>= exp - 1;
215 if (iy == 0)
216 return ix;
217
218 frac = (ix & 0x007fffff) | 0x00800000;
219 frac -= iy;
220 while (frac < 0x00800000) {
221 if (--exp == 0)
222 return frac;
223 frac <<= 1;
224 }
225
226 return (exp << 23) | (frac & 0x007fffff);
227 }
228
229 /* ix + iy where iy: denormal and ix, iy >= 0 */
230 static int denormal_addf1(unsigned int ix, unsigned int iy)
231 {
232 int frac;
233 int exp;
234
235 if (ix < 0x00800000)
236 return ix + iy;
237
238 exp = (ix & 0x7f800000) >> 23;
239 if (exp - 1 > 31)
240 return ix;
241 iy >>= exp - 1;
242 if (iy == 0)
243 return ix;
244
245 frac = (ix & 0x007fffff) | 0x00800000;
246 frac += iy;
247 if (frac >= 0x01000000) {
248 frac >>= 1;
249 ++exp;
250 }
251
252 return (exp << 23) | (frac & 0x007fffff);
253 }
254
255 static int denormal_addf(int hx, int hy)
256 {
257 unsigned int ix, iy;
258 int sign;
259
260 if ((hx ^ hy) & 0x80000000) {
261 sign = hx & 0x80000000;
262 ix = hx & 0x7fffffff;
263 iy = hy & 0x7fffffff;
264 if (iy < 0x00800000) {
265 ix = denormal_subf1(ix, iy);
266 if ((int) ix < 0) {
267 ix = -ix;
268 sign ^= 0x80000000;
269 }
270 } else {
271 ix = denormal_subf1(iy, ix);
272 sign ^= 0x80000000;
273 }
274 } else {
275 sign = hx & 0x80000000;
276 ix = hx & 0x7fffffff;
277 iy = hy & 0x7fffffff;
278 if (iy < 0x00800000)
279 ix = denormal_addf1(ix, iy);
280 else
281 ix = denormal_addf1(iy, ix);
282 }
283
284 return sign | ix;
285 }
286
287 /* ix - iy where iy: denormal and ix, iy >= 0 */
288 static long long denormal_subd1(unsigned long long ix, unsigned long long iy)
289 {
290 long long frac;
291 int exp;
292
293 if (ix < 0x0010000000000000LL)
294 return ix - iy;
295
296 exp = (ix & 0x7ff0000000000000LL) >> 52;
297 if (exp - 1 > 63)
298 return ix;
299 iy >>= exp - 1;
300 if (iy == 0)
301 return ix;
302
303 frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
304 frac -= iy;
305 while (frac < 0x0010000000000000LL) {
306 if (--exp == 0)
307 return frac;
308 frac <<= 1;
309 }
310
311 return ((long long)exp << 52) | (frac & 0x000fffffffffffffLL);
312 }
313
314 /* ix + iy where iy: denormal and ix, iy >= 0 */
315 static long long denormal_addd1(unsigned long long ix, unsigned long long iy)
316 {
317 long long frac;
318 long long exp;
319
320 if (ix < 0x0010000000000000LL)
321 return ix + iy;
322
323 exp = (ix & 0x7ff0000000000000LL) >> 52;
324 if (exp - 1 > 63)
325 return ix;
326 iy >>= exp - 1;
327 if (iy == 0)
328 return ix;
329
330 frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
331 frac += iy;
332 if (frac >= 0x0020000000000000LL) {
333 frac >>= 1;
334 ++exp;
335 }
336
337 return (exp << 52) | (frac & 0x000fffffffffffffLL);
338 }
339
340 static long long denormal_addd(long long hx, long long hy)
341 {
342 unsigned long long ix, iy;
343 long long sign;
344
345 if ((hx ^ hy) & 0x8000000000000000LL) {
346 sign = hx & 0x8000000000000000LL;
347 ix = hx & 0x7fffffffffffffffLL;
348 iy = hy & 0x7fffffffffffffffLL;
349 if (iy < 0x0010000000000000LL) {
350 ix = denormal_subd1(ix, iy);
351 if ((int) ix < 0) {
352 ix = -ix;
353 sign ^= 0x8000000000000000LL;
354 }
355 } else {
356 ix = denormal_subd1(iy, ix);
357 sign ^= 0x8000000000000000LL;
358 }
359 } else {
360 sign = hx & 0x8000000000000000LL;
361 ix = hx & 0x7fffffffffffffffLL;
362 iy = hy & 0x7fffffffffffffffLL;
363 if (iy < 0x0010000000000000LL)
364 ix = denormal_addd1(ix, iy);
365 else
366 ix = denormal_addd1(iy, ix);
367 }
368
369 return sign | ix;
370 }
371
372 /**
373 * denormal_to_double - Given denormalized float number,
374 * store double float
375 *
376 * @fpu: Pointer to sh_fpu_hard structure
377 * @n: Index to FP register
378 */
379 static void
380 denormal_to_double (struct sh_fpu_hard_struct *fpu, int n)
381 {
382 unsigned long du, dl;
383 unsigned long x = fpu->fpul;
384 int exp = 1023 - 126;
385
386 if (x != 0 && (x & 0x7f800000) == 0) {
387 du = (x & 0x80000000);
388 while ((x & 0x00800000) == 0) {
389 x <<= 1;
390 exp--;
391 }
392 x &= 0x007fffff;
393 du |= (exp << 20) | (x >> 3);
394 dl = x << 29;
395
396 fpu->fp_regs[n] = du;
397 fpu->fp_regs[n+1] = dl;
398 }
399 }
400
401 /**
402 * ieee_fpe_handler - Handle denormalized number exception
403 *
404 * @regs: Pointer to register structure
405 *
406 * Returns 1 when it's handled (should not cause exception).
407 */
408 static int
409 ieee_fpe_handler (struct pt_regs *regs)
410 {
411 unsigned short insn = *(unsigned short *) regs->pc;
412 unsigned short finsn;
413 unsigned long nextpc;
414 int nib[4] = {
415 (insn >> 12) & 0xf,
416 (insn >> 8) & 0xf,
417 (insn >> 4) & 0xf,
418 insn & 0xf};
419
420 if (nib[0] == 0xb ||
421 (nib[0] == 0x4 && nib[2] == 0x0 && nib[3] == 0xb)) /* bsr & jsr */
422 regs->pr = regs->pc + 4;
423 if (nib[0] == 0xa || nib[0] == 0xb) { /* bra & bsr */
424 nextpc = regs->pc + 4 + ((short) ((insn & 0xfff) << 4) >> 3);
425 finsn = *(unsigned short *) (regs->pc + 2);
426 } else if (nib[0] == 0x8 && nib[1] == 0xd) { /* bt/s */
427 if (regs->sr & 1)
428 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
429 else
430 nextpc = regs->pc + 4;
431 finsn = *(unsigned short *) (regs->pc + 2);
432 } else if (nib[0] == 0x8 && nib[1] == 0xf) { /* bf/s */
433 if (regs->sr & 1)
434 nextpc = regs->pc + 4;
435 else
436 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
437 finsn = *(unsigned short *) (regs->pc + 2);
438 } else if (nib[0] == 0x4 && nib[3] == 0xb &&
439 (nib[2] == 0x0 || nib[2] == 0x2)) { /* jmp & jsr */
440 nextpc = regs->regs[nib[1]];
441 finsn = *(unsigned short *) (regs->pc + 2);
442 } else if (nib[0] == 0x0 && nib[3] == 0x3 &&
443 (nib[2] == 0x0 || nib[2] == 0x2)) { /* braf & bsrf */
444 nextpc = regs->pc + 4 + regs->regs[nib[1]];
445 finsn = *(unsigned short *) (regs->pc + 2);
446 } else if (insn == 0x000b) { /* rts */
447 nextpc = regs->pr;
448 finsn = *(unsigned short *) (regs->pc + 2);
449 } else {
450 nextpc = regs->pc + 2;
451 finsn = insn;
452 }
453
454 #define FPSCR_FPU_ERROR (1 << 17)
455
456 if ((finsn & 0xf1ff) == 0xf0ad) { /* fcnvsd */
457 struct task_struct *tsk = current;
458
459 if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_FPU_ERROR)) {
460 /* FPU error */
461 denormal_to_double (&tsk->thread.xstate->hardfpu,
462 (finsn >> 8) & 0xf);
463 } else
464 return 0;
465
466 regs->pc = nextpc;
467 return 1;
468 } else if ((finsn & 0xf00f) == 0xf002) { /* fmul */
469 struct task_struct *tsk = current;
470 int fpscr;
471 int n, m, prec;
472 unsigned int hx, hy;
473
474 n = (finsn >> 8) & 0xf;
475 m = (finsn >> 4) & 0xf;
476 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
477 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
478 fpscr = tsk->thread.xstate->hardfpu.fpscr;
479 prec = fpscr & (1 << 19);
480
481 if ((fpscr & FPSCR_FPU_ERROR)
482 && (prec && ((hx & 0x7fffffff) < 0x00100000
483 || (hy & 0x7fffffff) < 0x00100000))) {
484 long long llx, lly;
485
486 /* FPU error because of denormal */
487 llx = ((long long) hx << 32)
488 | tsk->thread.xstate->hardfpu.fp_regs[n+1];
489 lly = ((long long) hy << 32)
490 | tsk->thread.xstate->hardfpu.fp_regs[m+1];
491 if ((hx & 0x7fffffff) >= 0x00100000)
492 llx = denormal_muld(lly, llx);
493 else
494 llx = denormal_muld(llx, lly);
495 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
496 tsk->thread.xstate->hardfpu.fp_regs[n+1] = llx & 0xffffffff;
497 } else if ((fpscr & FPSCR_FPU_ERROR)
498 && (!prec && ((hx & 0x7fffffff) < 0x00800000
499 || (hy & 0x7fffffff) < 0x00800000))) {
500 /* FPU error because of denormal */
501 if ((hx & 0x7fffffff) >= 0x00800000)
502 hx = denormal_mulf(hy, hx);
503 else
504 hx = denormal_mulf(hx, hy);
505 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
506 } else
507 return 0;
508
509 regs->pc = nextpc;
510 return 1;
511 } else if ((finsn & 0xf00e) == 0xf000) { /* fadd, fsub */
512 struct task_struct *tsk = current;
513 int fpscr;
514 int n, m, prec;
515 unsigned int hx, hy;
516
517 n = (finsn >> 8) & 0xf;
518 m = (finsn >> 4) & 0xf;
519 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
520 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
521 fpscr = tsk->thread.xstate->hardfpu.fpscr;
522 prec = fpscr & (1 << 19);
523
524 if ((fpscr & FPSCR_FPU_ERROR)
525 && (prec && ((hx & 0x7fffffff) < 0x00100000
526 || (hy & 0x7fffffff) < 0x00100000))) {
527 long long llx, lly;
528
529 /* FPU error because of denormal */
530 llx = ((long long) hx << 32)
531 | tsk->thread.xstate->hardfpu.fp_regs[n+1];
532 lly = ((long long) hy << 32)
533 | tsk->thread.xstate->hardfpu.fp_regs[m+1];
534 if ((finsn & 0xf00f) == 0xf000)
535 llx = denormal_addd(llx, lly);
536 else
537 llx = denormal_addd(llx, lly ^ (1LL << 63));
538 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
539 tsk->thread.xstate->hardfpu.fp_regs[n+1] = llx & 0xffffffff;
540 } else if ((fpscr & FPSCR_FPU_ERROR)
541 && (!prec && ((hx & 0x7fffffff) < 0x00800000
542 || (hy & 0x7fffffff) < 0x00800000))) {
543 /* FPU error because of denormal */
544 if ((finsn & 0xf00f) == 0xf000)
545 hx = denormal_addf(hx, hy);
546 else
547 hx = denormal_addf(hx, hy ^ 0x80000000);
548 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
549 } else
550 return 0;
551
552 regs->pc = nextpc;
553 return 1;
554 }
555
556 return 0;
557 }
558
559 BUILD_TRAP_HANDLER(fpu_error)
560 {
561 struct task_struct *tsk = current;
562 TRAP_HANDLER_DECL;
563
564 __unlazy_fpu(tsk, regs);
565 if (ieee_fpe_handler(regs)) {
566 tsk->thread.xstate->hardfpu.fpscr &=
567 ~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
568 grab_fpu(regs);
569 restore_fpu(tsk);
570 task_thread_info(tsk)->status |= TS_USEDFPU;
571 return;
572 }
573
574 force_sig(SIGFPE, tsk);
575 }
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