1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Save/restore floating point context for signal handlers.
4 *
5 * Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
6 *
7 * FIXME! These routines can be optimized in big endian case.
8 */
9 #include <linux/sched/signal.h>
10 #include <linux/signal.h>
11 #include <asm/processor.h>
12 #include <asm/io.h>
13 #include <asm/fpu.h>
14 #include <asm/traps.h>
15
16 /* The PR (precision) bit in the FP Status Register must be clear when
17 * an frchg instruction is executed, otherwise the instruction is undefined.
18 * Executing frchg with PR set causes a trap on some SH4 implementations.
19 */
20
21 #define FPSCR_RCHG 0x00000000
22
23
24 /*
25 * Save FPU registers onto task structure.
26 */
save_fpu(struct task_struct * tsk)27 void save_fpu(struct task_struct *tsk)
28 {
29 unsigned long dummy;
30
31 enable_fpu();
32 asm volatile("sts.l fpul, @-%0\n\t"
33 "sts.l fpscr, @-%0\n\t"
34 "fmov.s fr15, @-%0\n\t"
35 "fmov.s fr14, @-%0\n\t"
36 "fmov.s fr13, @-%0\n\t"
37 "fmov.s fr12, @-%0\n\t"
38 "fmov.s fr11, @-%0\n\t"
39 "fmov.s fr10, @-%0\n\t"
40 "fmov.s fr9, @-%0\n\t"
41 "fmov.s fr8, @-%0\n\t"
42 "fmov.s fr7, @-%0\n\t"
43 "fmov.s fr6, @-%0\n\t"
44 "fmov.s fr5, @-%0\n\t"
45 "fmov.s fr4, @-%0\n\t"
46 "fmov.s fr3, @-%0\n\t"
47 "fmov.s fr2, @-%0\n\t"
48 "fmov.s fr1, @-%0\n\t"
49 "fmov.s fr0, @-%0\n\t"
50 "lds %3, fpscr\n\t"
51 : "=r" (dummy)
52 : "0" ((char *)(&tsk->thread.xstate->hardfpu.status)),
53 "r" (FPSCR_RCHG),
54 "r" (FPSCR_INIT)
55 : "memory");
56
57 disable_fpu();
58 }
59
restore_fpu(struct task_struct * tsk)60 void restore_fpu(struct task_struct *tsk)
61 {
62 unsigned long dummy;
63
64 enable_fpu();
65 asm volatile("fmov.s @%0+, fr0\n\t"
66 "fmov.s @%0+, fr1\n\t"
67 "fmov.s @%0+, fr2\n\t"
68 "fmov.s @%0+, fr3\n\t"
69 "fmov.s @%0+, fr4\n\t"
70 "fmov.s @%0+, fr5\n\t"
71 "fmov.s @%0+, fr6\n\t"
72 "fmov.s @%0+, fr7\n\t"
73 "fmov.s @%0+, fr8\n\t"
74 "fmov.s @%0+, fr9\n\t"
75 "fmov.s @%0+, fr10\n\t"
76 "fmov.s @%0+, fr11\n\t"
77 "fmov.s @%0+, fr12\n\t"
78 "fmov.s @%0+, fr13\n\t"
79 "fmov.s @%0+, fr14\n\t"
80 "fmov.s @%0+, fr15\n\t"
81 "lds.l @%0+, fpscr\n\t"
82 "lds.l @%0+, fpul\n\t"
83 : "=r" (dummy)
84 : "0" (tsk->thread.xstate), "r" (FPSCR_RCHG)
85 : "memory");
86 disable_fpu();
87 }
88
89 /*
90 * Emulate arithmetic ops on denormalized number for some FPU insns.
91 */
92
93 /* denormalized float * float */
denormal_mulf(int hx,int hy)94 static int denormal_mulf(int hx, int hy)
95 {
96 unsigned int ix, iy;
97 unsigned long long m, n;
98 int exp, w;
99
100 ix = hx & 0x7fffffff;
101 iy = hy & 0x7fffffff;
102 if (iy < 0x00800000 || ix == 0)
103 return ((hx ^ hy) & 0x80000000);
104
105 exp = (iy & 0x7f800000) >> 23;
106 ix &= 0x007fffff;
107 iy = (iy & 0x007fffff) | 0x00800000;
108 m = (unsigned long long)ix * iy;
109 n = m;
110 w = -1;
111 while (n) { n >>= 1; w++; }
112
113 /* FIXME: use guard bits */
114 exp += w - 126 - 46;
115 if (exp > 0)
116 ix = ((int) (m >> (w - 23)) & 0x007fffff) | (exp << 23);
117 else if (exp + 22 >= 0)
118 ix = (int) (m >> (w - 22 - exp)) & 0x007fffff;
119 else
120 ix = 0;
121
122 ix |= (hx ^ hy) & 0x80000000;
123 return ix;
124 }
125
126 /* denormalized double * double */
mult64(unsigned long long x,unsigned long long y,unsigned long long * highp,unsigned long long * lowp)127 static void mult64(unsigned long long x, unsigned long long y,
128 unsigned long long *highp, unsigned long long *lowp)
129 {
130 unsigned long long sub0, sub1, sub2, sub3;
131 unsigned long long high, low;
132
133 sub0 = (x >> 32) * (unsigned long) (y >> 32);
134 sub1 = (x & 0xffffffffLL) * (unsigned long) (y >> 32);
135 sub2 = (x >> 32) * (unsigned long) (y & 0xffffffffLL);
136 sub3 = (x & 0xffffffffLL) * (unsigned long) (y & 0xffffffffLL);
137 low = sub3;
138 high = 0LL;
139 sub3 += (sub1 << 32);
140 if (low > sub3)
141 high++;
142 low = sub3;
143 sub3 += (sub2 << 32);
144 if (low > sub3)
145 high++;
146 low = sub3;
147 high += (sub1 >> 32) + (sub2 >> 32);
148 high += sub0;
149 *lowp = low;
150 *highp = high;
151 }
152
rshift64(unsigned long long mh,unsigned long long ml,int n)153 static inline long long rshift64(unsigned long long mh,
154 unsigned long long ml, int n)
155 {
156 if (n >= 64)
157 return mh >> (n - 64);
158 return (mh << (64 - n)) | (ml >> n);
159 }
160
denormal_muld(long long hx,long long hy)161 static long long denormal_muld(long long hx, long long hy)
162 {
163 unsigned long long ix, iy;
164 unsigned long long mh, ml, nh, nl;
165 int exp, w;
166
167 ix = hx & 0x7fffffffffffffffLL;
168 iy = hy & 0x7fffffffffffffffLL;
169 if (iy < 0x0010000000000000LL || ix == 0)
170 return ((hx ^ hy) & 0x8000000000000000LL);
171
172 exp = (iy & 0x7ff0000000000000LL) >> 52;
173 ix &= 0x000fffffffffffffLL;
174 iy = (iy & 0x000fffffffffffffLL) | 0x0010000000000000LL;
175 mult64(ix, iy, &mh, &ml);
176 nh = mh;
177 nl = ml;
178 w = -1;
179 if (nh) {
180 while (nh) { nh >>= 1; w++;}
181 w += 64;
182 } else
183 while (nl) { nl >>= 1; w++;}
184
185 /* FIXME: use guard bits */
186 exp += w - 1022 - 52 * 2;
187 if (exp > 0)
188 ix = (rshift64(mh, ml, w - 52) & 0x000fffffffffffffLL)
189 | ((long long)exp << 52);
190 else if (exp + 51 >= 0)
191 ix = rshift64(mh, ml, w - 51 - exp) & 0x000fffffffffffffLL;
192 else
193 ix = 0;
194
195 ix |= (hx ^ hy) & 0x8000000000000000LL;
196 return ix;
197 }
198
199 /* ix - iy where iy: denormal and ix, iy >= 0 */
denormal_subf1(unsigned int ix,unsigned int iy)200 static int denormal_subf1(unsigned int ix, unsigned int iy)
201 {
202 int frac;
203 int exp;
204
205 if (ix < 0x00800000)
206 return ix - iy;
207
208 exp = (ix & 0x7f800000) >> 23;
209 if (exp - 1 > 31)
210 return ix;
211 iy >>= exp - 1;
212 if (iy == 0)
213 return ix;
214
215 frac = (ix & 0x007fffff) | 0x00800000;
216 frac -= iy;
217 while (frac < 0x00800000) {
218 if (--exp == 0)
219 return frac;
220 frac <<= 1;
221 }
222
223 return (exp << 23) | (frac & 0x007fffff);
224 }
225
226 /* ix + iy where iy: denormal and ix, iy >= 0 */
denormal_addf1(unsigned int ix,unsigned int iy)227 static int denormal_addf1(unsigned int ix, unsigned int iy)
228 {
229 int frac;
230 int exp;
231
232 if (ix < 0x00800000)
233 return ix + iy;
234
235 exp = (ix & 0x7f800000) >> 23;
236 if (exp - 1 > 31)
237 return ix;
238 iy >>= exp - 1;
239 if (iy == 0)
240 return ix;
241
242 frac = (ix & 0x007fffff) | 0x00800000;
243 frac += iy;
244 if (frac >= 0x01000000) {
245 frac >>= 1;
246 ++exp;
247 }
248
249 return (exp << 23) | (frac & 0x007fffff);
250 }
251
denormal_addf(int hx,int hy)252 static int denormal_addf(int hx, int hy)
253 {
254 unsigned int ix, iy;
255 int sign;
256
257 if ((hx ^ hy) & 0x80000000) {
258 sign = hx & 0x80000000;
259 ix = hx & 0x7fffffff;
260 iy = hy & 0x7fffffff;
261 if (iy < 0x00800000) {
262 ix = denormal_subf1(ix, iy);
263 if ((int) ix < 0) {
264 ix = -ix;
265 sign ^= 0x80000000;
266 }
267 } else {
268 ix = denormal_subf1(iy, ix);
269 sign ^= 0x80000000;
270 }
271 } else {
272 sign = hx & 0x80000000;
273 ix = hx & 0x7fffffff;
274 iy = hy & 0x7fffffff;
275 if (iy < 0x00800000)
276 ix = denormal_addf1(ix, iy);
277 else
278 ix = denormal_addf1(iy, ix);
279 }
280
281 return sign | ix;
282 }
283
284 /* ix - iy where iy: denormal and ix, iy >= 0 */
denormal_subd1(unsigned long long ix,unsigned long long iy)285 static long long denormal_subd1(unsigned long long ix, unsigned long long iy)
286 {
287 long long frac;
288 int exp;
289
290 if (ix < 0x0010000000000000LL)
291 return ix - iy;
292
293 exp = (ix & 0x7ff0000000000000LL) >> 52;
294 if (exp - 1 > 63)
295 return ix;
296 iy >>= exp - 1;
297 if (iy == 0)
298 return ix;
299
300 frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
301 frac -= iy;
302 while (frac < 0x0010000000000000LL) {
303 if (--exp == 0)
304 return frac;
305 frac <<= 1;
306 }
307
308 return ((long long)exp << 52) | (frac & 0x000fffffffffffffLL);
309 }
310
311 /* ix + iy where iy: denormal and ix, iy >= 0 */
denormal_addd1(unsigned long long ix,unsigned long long iy)312 static long long denormal_addd1(unsigned long long ix, unsigned long long iy)
313 {
314 long long frac;
315 long long exp;
316
317 if (ix < 0x0010000000000000LL)
318 return ix + iy;
319
320 exp = (ix & 0x7ff0000000000000LL) >> 52;
321 if (exp - 1 > 63)
322 return ix;
323 iy >>= exp - 1;
324 if (iy == 0)
325 return ix;
326
327 frac = (ix & 0x000fffffffffffffLL) | 0x0010000000000000LL;
328 frac += iy;
329 if (frac >= 0x0020000000000000LL) {
330 frac >>= 1;
331 ++exp;
332 }
333
334 return (exp << 52) | (frac & 0x000fffffffffffffLL);
335 }
336
denormal_addd(long long hx,long long hy)337 static long long denormal_addd(long long hx, long long hy)
338 {
339 unsigned long long ix, iy;
340 long long sign;
341
342 if ((hx ^ hy) & 0x8000000000000000LL) {
343 sign = hx & 0x8000000000000000LL;
344 ix = hx & 0x7fffffffffffffffLL;
345 iy = hy & 0x7fffffffffffffffLL;
346 if (iy < 0x0010000000000000LL) {
347 ix = denormal_subd1(ix, iy);
348 if ((int) ix < 0) {
349 ix = -ix;
350 sign ^= 0x8000000000000000LL;
351 }
352 } else {
353 ix = denormal_subd1(iy, ix);
354 sign ^= 0x8000000000000000LL;
355 }
356 } else {
357 sign = hx & 0x8000000000000000LL;
358 ix = hx & 0x7fffffffffffffffLL;
359 iy = hy & 0x7fffffffffffffffLL;
360 if (iy < 0x0010000000000000LL)
361 ix = denormal_addd1(ix, iy);
362 else
363 ix = denormal_addd1(iy, ix);
364 }
365
366 return sign | ix;
367 }
368
369 /**
370 * denormal_to_double - Given denormalized float number,
371 * store double float
372 *
373 * @fpu: Pointer to sh_fpu_hard structure
374 * @n: Index to FP register
375 */
376 static void
denormal_to_double(struct sh_fpu_hard_struct * fpu,int n)377 denormal_to_double (struct sh_fpu_hard_struct *fpu, int n)
378 {
379 unsigned long du, dl;
380 unsigned long x = fpu->fpul;
381 int exp = 1023 - 126;
382
383 if (x != 0 && (x & 0x7f800000) == 0) {
384 du = (x & 0x80000000);
385 while ((x & 0x00800000) == 0) {
386 x <<= 1;
387 exp--;
388 }
389 x &= 0x007fffff;
390 du |= (exp << 20) | (x >> 3);
391 dl = x << 29;
392
393 fpu->fp_regs[n] = du;
394 fpu->fp_regs[n+1] = dl;
395 }
396 }
397
398 /**
399 * ieee_fpe_handler - Handle denormalized number exception
400 *
401 * @regs: Pointer to register structure
402 *
403 * Returns 1 when it's handled (should not cause exception).
404 */
405 static int
ieee_fpe_handler(struct pt_regs * regs)406 ieee_fpe_handler (struct pt_regs *regs)
407 {
408 unsigned short insn = *(unsigned short *) regs->pc;
409 unsigned short finsn;
410 unsigned long nextpc;
411 int nib[4] = {
412 (insn >> 12) & 0xf,
413 (insn >> 8) & 0xf,
414 (insn >> 4) & 0xf,
415 insn & 0xf};
416
417 if (nib[0] == 0xb ||
418 (nib[0] == 0x4 && nib[2] == 0x0 && nib[3] == 0xb)) /* bsr & jsr */
419 regs->pr = regs->pc + 4;
420 if (nib[0] == 0xa || nib[0] == 0xb) { /* bra & bsr */
421 nextpc = regs->pc + 4 + ((short) ((insn & 0xfff) << 4) >> 3);
422 finsn = *(unsigned short *) (regs->pc + 2);
423 } else if (nib[0] == 0x8 && nib[1] == 0xd) { /* bt/s */
424 if (regs->sr & 1)
425 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
426 else
427 nextpc = regs->pc + 4;
428 finsn = *(unsigned short *) (regs->pc + 2);
429 } else if (nib[0] == 0x8 && nib[1] == 0xf) { /* bf/s */
430 if (regs->sr & 1)
431 nextpc = regs->pc + 4;
432 else
433 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
434 finsn = *(unsigned short *) (regs->pc + 2);
435 } else if (nib[0] == 0x4 && nib[3] == 0xb &&
436 (nib[2] == 0x0 || nib[2] == 0x2)) { /* jmp & jsr */
437 nextpc = regs->regs[nib[1]];
438 finsn = *(unsigned short *) (regs->pc + 2);
439 } else if (nib[0] == 0x0 && nib[3] == 0x3 &&
440 (nib[2] == 0x0 || nib[2] == 0x2)) { /* braf & bsrf */
441 nextpc = regs->pc + 4 + regs->regs[nib[1]];
442 finsn = *(unsigned short *) (regs->pc + 2);
443 } else if (insn == 0x000b) { /* rts */
444 nextpc = regs->pr;
445 finsn = *(unsigned short *) (regs->pc + 2);
446 } else {
447 nextpc = regs->pc + 2;
448 finsn = insn;
449 }
450
451 #define FPSCR_FPU_ERROR (1 << 17)
452
453 if ((finsn & 0xf1ff) == 0xf0ad) { /* fcnvsd */
454 struct task_struct *tsk = current;
455
456 if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_FPU_ERROR)) {
457 /* FPU error */
458 denormal_to_double (&tsk->thread.xstate->hardfpu,
459 (finsn >> 8) & 0xf);
460 } else
461 return 0;
462
463 regs->pc = nextpc;
464 return 1;
465 } else if ((finsn & 0xf00f) == 0xf002) { /* fmul */
466 struct task_struct *tsk = current;
467 int fpscr;
468 int n, m, prec;
469 unsigned int hx, hy;
470
471 n = (finsn >> 8) & 0xf;
472 m = (finsn >> 4) & 0xf;
473 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
474 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
475 fpscr = tsk->thread.xstate->hardfpu.fpscr;
476 prec = fpscr & (1 << 19);
477
478 if ((fpscr & FPSCR_FPU_ERROR)
479 && (prec && ((hx & 0x7fffffff) < 0x00100000
480 || (hy & 0x7fffffff) < 0x00100000))) {
481 long long llx, lly;
482
483 /* FPU error because of denormal */
484 llx = ((long long) hx << 32)
485 | tsk->thread.xstate->hardfpu.fp_regs[n+1];
486 lly = ((long long) hy << 32)
487 | tsk->thread.xstate->hardfpu.fp_regs[m+1];
488 if ((hx & 0x7fffffff) >= 0x00100000)
489 llx = denormal_muld(lly, llx);
490 else
491 llx = denormal_muld(llx, lly);
492 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
493 tsk->thread.xstate->hardfpu.fp_regs[n+1] = llx & 0xffffffff;
494 } else if ((fpscr & FPSCR_FPU_ERROR)
495 && (!prec && ((hx & 0x7fffffff) < 0x00800000
496 || (hy & 0x7fffffff) < 0x00800000))) {
497 /* FPU error because of denormal */
498 if ((hx & 0x7fffffff) >= 0x00800000)
499 hx = denormal_mulf(hy, hx);
500 else
501 hx = denormal_mulf(hx, hy);
502 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
503 } else
504 return 0;
505
506 regs->pc = nextpc;
507 return 1;
508 } else if ((finsn & 0xf00e) == 0xf000) { /* fadd, fsub */
509 struct task_struct *tsk = current;
510 int fpscr;
511 int n, m, prec;
512 unsigned int hx, hy;
513
514 n = (finsn >> 8) & 0xf;
515 m = (finsn >> 4) & 0xf;
516 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
517 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
518 fpscr = tsk->thread.xstate->hardfpu.fpscr;
519 prec = fpscr & (1 << 19);
520
521 if ((fpscr & FPSCR_FPU_ERROR)
522 && (prec && ((hx & 0x7fffffff) < 0x00100000
523 || (hy & 0x7fffffff) < 0x00100000))) {
524 long long llx, lly;
525
526 /* FPU error because of denormal */
527 llx = ((long long) hx << 32)
528 | tsk->thread.xstate->hardfpu.fp_regs[n+1];
529 lly = ((long long) hy << 32)
530 | tsk->thread.xstate->hardfpu.fp_regs[m+1];
531 if ((finsn & 0xf00f) == 0xf000)
532 llx = denormal_addd(llx, lly);
533 else
534 llx = denormal_addd(llx, lly ^ (1LL << 63));
535 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
536 tsk->thread.xstate->hardfpu.fp_regs[n+1] = llx & 0xffffffff;
537 } else if ((fpscr & FPSCR_FPU_ERROR)
538 && (!prec && ((hx & 0x7fffffff) < 0x00800000
539 || (hy & 0x7fffffff) < 0x00800000))) {
540 /* FPU error because of denormal */
541 if ((finsn & 0xf00f) == 0xf000)
542 hx = denormal_addf(hx, hy);
543 else
544 hx = denormal_addf(hx, hy ^ 0x80000000);
545 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
546 } else
547 return 0;
548
549 regs->pc = nextpc;
550 return 1;
551 }
552
553 return 0;
554 }
555
BUILD_TRAP_HANDLER(fpu_error)556 BUILD_TRAP_HANDLER(fpu_error)
557 {
558 struct task_struct *tsk = current;
559 TRAP_HANDLER_DECL;
560
561 __unlazy_fpu(tsk, regs);
562 if (ieee_fpe_handler(regs)) {
563 tsk->thread.xstate->hardfpu.fpscr &=
564 ~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
565 grab_fpu(regs);
566 restore_fpu(tsk);
567 task_thread_info(tsk)->status |= TS_USEDFPU;
568 return;
569 }
570
571 force_sig(SIGFPE);
572 }
573