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Merge tag 'v3.3.7' into 3.3/master
[zen-stable.git] / arch / sh / kernel / cpu / sh2a / fpu.c
blob488d24e0cdf0b1aa59988a17afc7a9edd9a7e898
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
18 /* The PR (precision) bit in the FP Status Register must be clear when
19 * an frchg instruction is executed, otherwise the instruction is undefined.
20 * Executing frchg with PR set causes a trap on some SH4 implementations.
21 */
22
23 #define FPSCR_RCHG 0x00000000
24
25
26 /*
27 * Save FPU registers onto task structure.
28 */
29 void save_fpu(struct task_struct *tsk)
30 {
31 unsigned long dummy;
32
33 enable_fpu();
34 asm volatile("sts.l fpul, @-%0\n\t"
35 "sts.l fpscr, @-%0\n\t"
36 "fmov.s fr15, @-%0\n\t"
37 "fmov.s fr14, @-%0\n\t"
38 "fmov.s fr13, @-%0\n\t"
39 "fmov.s fr12, @-%0\n\t"
40 "fmov.s fr11, @-%0\n\t"
41 "fmov.s fr10, @-%0\n\t"
42 "fmov.s fr9, @-%0\n\t"
43 "fmov.s fr8, @-%0\n\t"
44 "fmov.s fr7, @-%0\n\t"
45 "fmov.s fr6, @-%0\n\t"
46 "fmov.s fr5, @-%0\n\t"
47 "fmov.s fr4, @-%0\n\t"
48 "fmov.s fr3, @-%0\n\t"
49 "fmov.s fr2, @-%0\n\t"
50 "fmov.s fr1, @-%0\n\t"
51 "fmov.s fr0, @-%0\n\t"
52 "lds %3, fpscr\n\t"
53 : "=r" (dummy)
54 : "0" ((char *)(&tsk->thread.xstate->hardfpu.status)),
55 "r" (FPSCR_RCHG),
56 "r" (FPSCR_INIT)
57 : "memory");
58
59 disable_fpu();
60 }
61
62 void restore_fpu(struct task_struct *tsk)
63 {
64 unsigned long dummy;
65
66 enable_fpu();
67 asm volatile("fmov.s @%0+, fr0\n\t"
68 "fmov.s @%0+, fr1\n\t"
69 "fmov.s @%0+, fr2\n\t"
70 "fmov.s @%0+, fr3\n\t"
71 "fmov.s @%0+, fr4\n\t"
72 "fmov.s @%0+, fr5\n\t"
73 "fmov.s @%0+, fr6\n\t"
74 "fmov.s @%0+, fr7\n\t"
75 "fmov.s @%0+, fr8\n\t"
76 "fmov.s @%0+, fr9\n\t"
77 "fmov.s @%0+, fr10\n\t"
78 "fmov.s @%0+, fr11\n\t"
79 "fmov.s @%0+, fr12\n\t"
80 "fmov.s @%0+, fr13\n\t"
81 "fmov.s @%0+, fr14\n\t"
82 "fmov.s @%0+, fr15\n\t"
83 "lds.l @%0+, fpscr\n\t"
84 "lds.l @%0+, fpul\n\t"
85 : "=r" (dummy)
86 : "0" (tsk->thread.xstate), "r" (FPSCR_RCHG)
87 : "memory");
88 disable_fpu();
89 }
90
91 /*
92 * Emulate arithmetic ops on denormalized number for some FPU insns.
93 */
94
95 /* denormalized float * float */
96 static int denormal_mulf(int hx, int hy)
97 {
98 unsigned int ix, iy;
99 unsigned long long m, n;
100 int exp, w;
101
102 ix = hx & 0x7fffffff;
103 iy = hy & 0x7fffffff;
104 if (iy < 0x00800000 || ix == 0)
105 return ((hx ^ hy) & 0x80000000);
106
107 exp = (iy & 0x7f800000) >> 23;
108 ix &= 0x007fffff;
109 iy = (iy & 0x007fffff) | 0x00800000;
110 m = (unsigned long long)ix * iy;
111 n = m;
112 w = -1;
113 while (n) { n >>= 1; w++; }
114
115 /* FIXME: use guard bits */
116 exp += w - 126 - 46;
117 if (exp > 0)
118 ix = ((int) (m >> (w - 23)) & 0x007fffff) | (exp << 23);
119 else if (exp + 22 >= 0)
120 ix = (int) (m >> (w - 22 - exp)) & 0x007fffff;
121 else
122 ix = 0;
123
124 ix |= (hx ^ hy) & 0x80000000;
125 return ix;
126 }
127
128 /* denormalized double * double */
129 static void mult64(unsigned long long x, unsigned long long y,
130 unsigned long long *highp, unsigned long long *lowp)
131 {
132 unsigned long long sub0, sub1, sub2, sub3;
133 unsigned long long high, low;
134
135 sub0 = (x >> 32) * (unsigned long) (y >> 32);
136 sub1 = (x & 0xffffffffLL) * (unsigned long) (y >> 32);
137 sub2 = (x >> 32) * (unsigned long) (y & 0xffffffffLL);
138 sub3 = (x & 0xffffffffLL) * (unsigned long) (y & 0xffffffffLL);
139 low = sub3;
140 high = 0LL;
141 sub3 += (sub1 << 32);
142 if (low > sub3)
143 high++;
144 low = sub3;
145 sub3 += (sub2 << 32);
146 if (low > sub3)
147 high++;
148 low = sub3;
149 high += (sub1 >> 32) + (sub2 >> 32);
150 high += sub0;
151 *lowp = low;
152 *highp = high;
153 }
154
155 static inline long long rshift64(unsigned long long mh,
156 unsigned long long ml, int n)
157 {
158 if (n >= 64)
159 return mh >> (n - 64);
160 return (mh << (64 - n)) | (ml >> n);
161 }
162
163 static long long denormal_muld(long long hx, long long hy)
164 {
165 unsigned long long ix, iy;
166 unsigned long long mh, ml, nh, nl;
167 int exp, w;
168
169 ix = hx & 0x7fffffffffffffffLL;
170 iy = hy & 0x7fffffffffffffffLL;
171 if (iy < 0x0010000000000000LL || ix == 0)
172 return ((hx ^ hy) & 0x8000000000000000LL);
173
174 exp = (iy & 0x7ff0000000000000LL) >> 52;
175 ix &= 0x000fffffffffffffLL;
176 iy = (iy & 0x000fffffffffffffLL) | 0x0010000000000000LL;
177 mult64(ix, iy, &mh, &ml);
178 nh = mh;
179 nl = ml;
180 w = -1;
181 if (nh) {
182 while (nh) { nh >>= 1; w++;}
183 w += 64;
184 } else
185 while (nl) { nl >>= 1; w++;}
186
187 /* FIXME: use guard bits */
188 exp += w - 1022 - 52 * 2;
189 if (exp > 0)
190 ix = (rshift64(mh, ml, w - 52) & 0x000fffffffffffffLL)
191 | ((long long)exp << 52);
192 else if (exp + 51 >= 0)
193 ix = rshift64(mh, ml, w - 51 - exp) & 0x000fffffffffffffLL;
194 else
195 ix = 0;
196
197 ix |= (hx ^ hy) & 0x8000000000000000LL;
198 return ix;
199 }
200
201 /* ix - iy where iy: denormal and ix, iy >= 0 */
202 static int denormal_subf1(unsigned int ix, unsigned int iy)
203 {
204 int frac;
205 int exp;
206
207 if (ix < 0x00800000)
208 return ix - iy;
209
210 exp = (ix & 0x7f800000) >> 23;
211 if (exp - 1 > 31)
212 return ix;
213 iy >>= exp - 1;
214 if (iy == 0)
215 return ix;
216
217 frac = (ix & 0x007fffff) | 0x00800000;
218 frac -= iy;
219 while (frac < 0x00800000) {
220 if (--exp == 0)
221 return frac;
222 frac <<= 1;
223 }
224
225 return (exp << 23) | (frac & 0x007fffff);
226 }
227
228 /* ix + iy where iy: denormal and ix, iy >= 0 */
229 static int denormal_addf1(unsigned int ix, unsigned int iy)
230 {
231 int frac;
232 int exp;
233
234 if (ix < 0x00800000)
235 return ix + iy;
236
237 exp = (ix & 0x7f800000) >> 23;
238 if (exp - 1 > 31)
239 return ix;
240 iy >>= exp - 1;
241 if (iy == 0)
242 return ix;
243
244 frac = (ix & 0x007fffff) | 0x00800000;
245 frac += iy;
246 if (frac >= 0x01000000) {
247 frac >>= 1;
248 ++exp;
249 }
250
251 return (exp << 23) | (frac & 0x007fffff);
252 }
253
254 static int denormal_addf(int hx, int hy)
255 {
256 unsigned int ix, iy;
257 int sign;
258
259 if ((hx ^ hy) & 0x80000000) {
260 sign = hx & 0x80000000;
261 ix = hx & 0x7fffffff;
262 iy = hy & 0x7fffffff;
263 if (iy < 0x00800000) {
264 ix = denormal_subf1(ix, iy);
265 if ((int) ix < 0) {
266 ix = -ix;
267 sign ^= 0x80000000;
268 }
269 } else {
270 ix = denormal_subf1(iy, ix);
271 sign ^= 0x80000000;
272 }
273 } else {
274 sign = hx & 0x80000000;
275 ix = hx & 0x7fffffff;
276 iy = hy & 0x7fffffff;
277 if (iy < 0x00800000)
278 ix = denormal_addf1(ix, iy);
279 else
280 ix = denormal_addf1(iy, ix);
281 }
282
283 return sign | ix;
284 }
285
286 /* ix - iy where iy: denormal and ix, iy >= 0 */
287 static long long denormal_subd1(unsigned long long ix, unsigned long long iy)
288 {
289 long long frac;
290 int exp;
291
292 if (ix < 0x0010000000000000LL)
293 return ix - iy;
294
295 exp = (ix & 0x7ff0000000000000LL) >> 52;
296 if (exp - 1 > 63)
297 return ix;
298 iy >>= exp - 1;
299 if (iy == 0)
300 return ix;
301
302 frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
303 frac -= iy;
304 while (frac < 0x0010000000000000LL) {
305 if (--exp == 0)
306 return frac;
307 frac <<= 1;
308 }
309
310 return ((long long)exp << 52) | (frac & 0x000fffffffffffffLL);
311 }
312
313 /* ix + iy where iy: denormal and ix, iy >= 0 */
314 static long long denormal_addd1(unsigned long long ix, unsigned long long iy)
315 {
316 long long frac;
317 long long exp;
318
319 if (ix < 0x0010000000000000LL)
320 return ix + iy;
321
322 exp = (ix & 0x7ff0000000000000LL) >> 52;
323 if (exp - 1 > 63)
324 return ix;
325 iy >>= exp - 1;
326 if (iy == 0)
327 return ix;
328
329 frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
330 frac += iy;
331 if (frac >= 0x0020000000000000LL) {
332 frac >>= 1;
333 ++exp;
334 }
335
336 return (exp << 52) | (frac & 0x000fffffffffffffLL);
337 }
338
339 static long long denormal_addd(long long hx, long long hy)
340 {
341 unsigned long long ix, iy;
342 long long sign;
343
344 if ((hx ^ hy) & 0x8000000000000000LL) {
345 sign = hx & 0x8000000000000000LL;
346 ix = hx & 0x7fffffffffffffffLL;
347 iy = hy & 0x7fffffffffffffffLL;
348 if (iy < 0x0010000000000000LL) {
349 ix = denormal_subd1(ix, iy);
350 if ((int) ix < 0) {
351 ix = -ix;
352 sign ^= 0x8000000000000000LL;
353 }
354 } else {
355 ix = denormal_subd1(iy, ix);
356 sign ^= 0x8000000000000000LL;
357 }
358 } else {
359 sign = hx & 0x8000000000000000LL;
360 ix = hx & 0x7fffffffffffffffLL;
361 iy = hy & 0x7fffffffffffffffLL;
362 if (iy < 0x0010000000000000LL)
363 ix = denormal_addd1(ix, iy);
364 else
365 ix = denormal_addd1(iy, ix);
366 }
367
368 return sign | ix;
369 }
370
371 /**
372 * denormal_to_double - Given denormalized float number,
373 * store double float
374 *
375 * @fpu: Pointer to sh_fpu_hard structure
376 * @n: Index to FP register
377 */
378 static void
379 denormal_to_double (struct sh_fpu_hard_struct *fpu, int n)
380 {
381 unsigned long du, dl;
382 unsigned long x = fpu->fpul;
383 int exp = 1023 - 126;
384
385 if (x != 0 && (x & 0x7f800000) == 0) {
386 du = (x & 0x80000000);
387 while ((x & 0x00800000) == 0) {
388 x <<= 1;
389 exp--;
390 }
391 x &= 0x007fffff;
392 du |= (exp << 20) | (x >> 3);
393 dl = x << 29;
394
395 fpu->fp_regs[n] = du;
396 fpu->fp_regs[n+1] = dl;
397 }
398 }
399
400 /**
401 * ieee_fpe_handler - Handle denormalized number exception
402 *
403 * @regs: Pointer to register structure
404 *
405 * Returns 1 when it's handled (should not cause exception).
406 */
407 static int
408 ieee_fpe_handler (struct pt_regs *regs)
409 {
410 unsigned short insn = *(unsigned short *) regs->pc;
411 unsigned short finsn;
412 unsigned long nextpc;
413 int nib[4] = {
414 (insn >> 12) & 0xf,
415 (insn >> 8) & 0xf,
416 (insn >> 4) & 0xf,
417 insn & 0xf};
418
419 if (nib[0] == 0xb ||
420 (nib[0] == 0x4 && nib[2] == 0x0 && nib[3] == 0xb)) /* bsr & jsr */
421 regs->pr = regs->pc + 4;
422 if (nib[0] == 0xa || nib[0] == 0xb) { /* bra & bsr */
423 nextpc = regs->pc + 4 + ((short) ((insn & 0xfff) << 4) >> 3);
424 finsn = *(unsigned short *) (regs->pc + 2);
425 } else if (nib[0] == 0x8 && nib[1] == 0xd) { /* bt/s */
426 if (regs->sr & 1)
427 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
428 else
429 nextpc = regs->pc + 4;
430 finsn = *(unsigned short *) (regs->pc + 2);
431 } else if (nib[0] == 0x8 && nib[1] == 0xf) { /* bf/s */
432 if (regs->sr & 1)
433 nextpc = regs->pc + 4;
434 else
435 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
436 finsn = *(unsigned short *) (regs->pc + 2);
437 } else if (nib[0] == 0x4 && nib[3] == 0xb &&
438 (nib[2] == 0x0 || nib[2] == 0x2)) { /* jmp & jsr */
439 nextpc = regs->regs[nib[1]];
440 finsn = *(unsigned short *) (regs->pc + 2);
441 } else if (nib[0] == 0x0 && nib[3] == 0x3 &&
442 (nib[2] == 0x0 || nib[2] == 0x2)) { /* braf & bsrf */
443 nextpc = regs->pc + 4 + regs->regs[nib[1]];
444 finsn = *(unsigned short *) (regs->pc + 2);
445 } else if (insn == 0x000b) { /* rts */
446 nextpc = regs->pr;
447 finsn = *(unsigned short *) (regs->pc + 2);
448 } else {
449 nextpc = regs->pc + 2;
450 finsn = insn;
451 }
452
453 #define FPSCR_FPU_ERROR (1 << 17)
454
455 if ((finsn & 0xf1ff) == 0xf0ad) { /* fcnvsd */
456 struct task_struct *tsk = current;
457
458 if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_FPU_ERROR)) {
459 /* FPU error */
460 denormal_to_double (&tsk->thread.xstate->hardfpu,
461 (finsn >> 8) & 0xf);
462 } else
463 return 0;
464
465 regs->pc = nextpc;
466 return 1;
467 } else if ((finsn & 0xf00f) == 0xf002) { /* fmul */
468 struct task_struct *tsk = current;
469 int fpscr;
470 int n, m, prec;
471 unsigned int hx, hy;
472
473 n = (finsn >> 8) & 0xf;
474 m = (finsn >> 4) & 0xf;
475 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
476 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
477 fpscr = tsk->thread.xstate->hardfpu.fpscr;
478 prec = fpscr & (1 << 19);
479
480 if ((fpscr & FPSCR_FPU_ERROR)
481 && (prec && ((hx & 0x7fffffff) < 0x00100000
482 || (hy & 0x7fffffff) < 0x00100000))) {
483 long long llx, lly;
484
485 /* FPU error because of denormal */
486 llx = ((long long) hx << 32)
487 | tsk->thread.xstate->hardfpu.fp_regs[n+1];
488 lly = ((long long) hy << 32)
489 | tsk->thread.xstate->hardfpu.fp_regs[m+1];
490 if ((hx & 0x7fffffff) >= 0x00100000)
491 llx = denormal_muld(lly, llx);
492 else
493 llx = denormal_muld(llx, lly);
494 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
495 tsk->thread.xstate->hardfpu.fp_regs[n+1] = llx & 0xffffffff;
496 } else if ((fpscr & FPSCR_FPU_ERROR)
497 && (!prec && ((hx & 0x7fffffff) < 0x00800000
498 || (hy & 0x7fffffff) < 0x00800000))) {
499 /* FPU error because of denormal */
500 if ((hx & 0x7fffffff) >= 0x00800000)
501 hx = denormal_mulf(hy, hx);
502 else
503 hx = denormal_mulf(hx, hy);
504 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
505 } else
506 return 0;
507
508 regs->pc = nextpc;
509 return 1;
510 } else if ((finsn & 0xf00e) == 0xf000) { /* fadd, fsub */
511 struct task_struct *tsk = current;
512 int fpscr;
513 int n, m, prec;
514 unsigned int hx, hy;
515
516 n = (finsn >> 8) & 0xf;
517 m = (finsn >> 4) & 0xf;
518 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
519 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
520 fpscr = tsk->thread.xstate->hardfpu.fpscr;
521 prec = fpscr & (1 << 19);
522
523 if ((fpscr & FPSCR_FPU_ERROR)
524 && (prec && ((hx & 0x7fffffff) < 0x00100000
525 || (hy & 0x7fffffff) < 0x00100000))) {
526 long long llx, lly;
527
528 /* FPU error because of denormal */
529 llx = ((long long) hx << 32)
530 | tsk->thread.xstate->hardfpu.fp_regs[n+1];
531 lly = ((long long) hy << 32)
532 | tsk->thread.xstate->hardfpu.fp_regs[m+1];
533 if ((finsn & 0xf00f) == 0xf000)
534 llx = denormal_addd(llx, lly);
535 else
536 llx = denormal_addd(llx, lly ^ (1LL << 63));
537 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
538 tsk->thread.xstate->hardfpu.fp_regs[n+1] = llx & 0xffffffff;
539 } else if ((fpscr & FPSCR_FPU_ERROR)
540 && (!prec && ((hx & 0x7fffffff) < 0x00800000
541 || (hy & 0x7fffffff) < 0x00800000))) {
542 /* FPU error because of denormal */
543 if ((finsn & 0xf00f) == 0xf000)
544 hx = denormal_addf(hx, hy);
545 else
546 hx = denormal_addf(hx, hy ^ 0x80000000);
547 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
548 } else
549 return 0;
550
551 regs->pc = nextpc;
552 return 1;
553 }
554
555 return 0;
556 }
557
558 BUILD_TRAP_HANDLER(fpu_error)
559 {
560 struct task_struct *tsk = current;
561 TRAP_HANDLER_DECL;
562
563 __unlazy_fpu(tsk, regs);
564 if (ieee_fpe_handler(regs)) {
565 tsk->thread.xstate->hardfpu.fpscr &=
566 ~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
567 grab_fpu(regs);
568 restore_fpu(tsk);
569 task_thread_info(tsk)->status |= TS_USEDFPU;
570 return;
571 }
572
573 force_sig(SIGFPE, tsk);
574 }