1 /*
2 * Save/restore floating point context for signal handlers.
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
9 * Copyright (C) 2006 ST Microelectronics Ltd. (denorm support)
10 *
11 * FIXME! These routines have not been tested for big endian case.
12 */
13 #include <linux/sched/signal.h>
14 #include <linux/io.h>
15 #include <cpu/fpu.h>
16 #include <asm/processor.h>
17 #include <asm/fpu.h>
18 #include <asm/traps.h>
19
20 /* The PR (precision) bit in the FP Status Register must be clear when
21 * an frchg instruction is executed, otherwise the instruction is undefined.
22 * Executing frchg with PR set causes a trap on some SH4 implementations.
23 */
24
25 #define FPSCR_RCHG 0x00000000
26 extern unsigned long long float64_div(unsigned long long a,
27 unsigned long long b);
28 extern unsigned long int float32_div(unsigned long int a, unsigned long int b);
29 extern unsigned long long float64_mul(unsigned long long a,
30 unsigned long long b);
31 extern unsigned long int float32_mul(unsigned long int a, unsigned long int b);
32 extern unsigned long long float64_add(unsigned long long a,
33 unsigned long long b);
34 extern unsigned long int float32_add(unsigned long int a, unsigned long int b);
35 extern unsigned long long float64_sub(unsigned long long a,
36 unsigned long long b);
37 extern unsigned long int float32_sub(unsigned long int a, unsigned long int b);
38 extern unsigned long int float64_to_float32(unsigned long long a);
39 static unsigned int fpu_exception_flags;
40
41 /*
42 * Save FPU registers onto task structure.
43 */
save_fpu(struct task_struct * tsk)44 void save_fpu(struct task_struct *tsk)
45 {
46 unsigned long dummy;
47
48 enable_fpu();
49 asm volatile ("sts.l fpul, @-%0\n\t"
50 "sts.l fpscr, @-%0\n\t"
51 "lds %2, fpscr\n\t"
52 "frchg\n\t"
53 "fmov.s fr15, @-%0\n\t"
54 "fmov.s fr14, @-%0\n\t"
55 "fmov.s fr13, @-%0\n\t"
56 "fmov.s fr12, @-%0\n\t"
57 "fmov.s fr11, @-%0\n\t"
58 "fmov.s fr10, @-%0\n\t"
59 "fmov.s fr9, @-%0\n\t"
60 "fmov.s fr8, @-%0\n\t"
61 "fmov.s fr7, @-%0\n\t"
62 "fmov.s fr6, @-%0\n\t"
63 "fmov.s fr5, @-%0\n\t"
64 "fmov.s fr4, @-%0\n\t"
65 "fmov.s fr3, @-%0\n\t"
66 "fmov.s fr2, @-%0\n\t"
67 "fmov.s fr1, @-%0\n\t"
68 "fmov.s fr0, @-%0\n\t"
69 "frchg\n\t"
70 "fmov.s fr15, @-%0\n\t"
71 "fmov.s fr14, @-%0\n\t"
72 "fmov.s fr13, @-%0\n\t"
73 "fmov.s fr12, @-%0\n\t"
74 "fmov.s fr11, @-%0\n\t"
75 "fmov.s fr10, @-%0\n\t"
76 "fmov.s fr9, @-%0\n\t"
77 "fmov.s fr8, @-%0\n\t"
78 "fmov.s fr7, @-%0\n\t"
79 "fmov.s fr6, @-%0\n\t"
80 "fmov.s fr5, @-%0\n\t"
81 "fmov.s fr4, @-%0\n\t"
82 "fmov.s fr3, @-%0\n\t"
83 "fmov.s fr2, @-%0\n\t"
84 "fmov.s fr1, @-%0\n\t"
85 "fmov.s fr0, @-%0\n\t"
86 "lds %3, fpscr\n\t":"=r" (dummy)
87 :"0"((char *)(&tsk->thread.xstate->hardfpu.status)),
88 "r"(FPSCR_RCHG), "r"(FPSCR_INIT)
89 :"memory");
90
91 disable_fpu();
92 }
93
restore_fpu(struct task_struct * tsk)94 void restore_fpu(struct task_struct *tsk)
95 {
96 unsigned long dummy;
97
98 enable_fpu();
99 asm volatile ("lds %2, fpscr\n\t"
100 "fmov.s @%0+, fr0\n\t"
101 "fmov.s @%0+, fr1\n\t"
102 "fmov.s @%0+, fr2\n\t"
103 "fmov.s @%0+, fr3\n\t"
104 "fmov.s @%0+, fr4\n\t"
105 "fmov.s @%0+, fr5\n\t"
106 "fmov.s @%0+, fr6\n\t"
107 "fmov.s @%0+, fr7\n\t"
108 "fmov.s @%0+, fr8\n\t"
109 "fmov.s @%0+, fr9\n\t"
110 "fmov.s @%0+, fr10\n\t"
111 "fmov.s @%0+, fr11\n\t"
112 "fmov.s @%0+, fr12\n\t"
113 "fmov.s @%0+, fr13\n\t"
114 "fmov.s @%0+, fr14\n\t"
115 "fmov.s @%0+, fr15\n\t"
116 "frchg\n\t"
117 "fmov.s @%0+, fr0\n\t"
118 "fmov.s @%0+, fr1\n\t"
119 "fmov.s @%0+, fr2\n\t"
120 "fmov.s @%0+, fr3\n\t"
121 "fmov.s @%0+, fr4\n\t"
122 "fmov.s @%0+, fr5\n\t"
123 "fmov.s @%0+, fr6\n\t"
124 "fmov.s @%0+, fr7\n\t"
125 "fmov.s @%0+, fr8\n\t"
126 "fmov.s @%0+, fr9\n\t"
127 "fmov.s @%0+, fr10\n\t"
128 "fmov.s @%0+, fr11\n\t"
129 "fmov.s @%0+, fr12\n\t"
130 "fmov.s @%0+, fr13\n\t"
131 "fmov.s @%0+, fr14\n\t"
132 "fmov.s @%0+, fr15\n\t"
133 "frchg\n\t"
134 "lds.l @%0+, fpscr\n\t"
135 "lds.l @%0+, fpul\n\t"
136 :"=r" (dummy)
137 :"0" (tsk->thread.xstate), "r" (FPSCR_RCHG)
138 :"memory");
139 disable_fpu();
140 }
141
142 /**
143 * denormal_to_double - Given denormalized float number,
144 * store double float
145 *
146 * @fpu: Pointer to sh_fpu_hard structure
147 * @n: Index to FP register
148 */
denormal_to_double(struct sh_fpu_hard_struct * fpu,int n)149 static void denormal_to_double(struct sh_fpu_hard_struct *fpu, int n)
150 {
151 unsigned long du, dl;
152 unsigned long x = fpu->fpul;
153 int exp = 1023 - 126;
154
155 if (x != 0 && (x & 0x7f800000) == 0) {
156 du = (x & 0x80000000);
157 while ((x & 0x00800000) == 0) {
158 x <<= 1;
159 exp--;
160 }
161 x &= 0x007fffff;
162 du |= (exp << 20) | (x >> 3);
163 dl = x << 29;
164
165 fpu->fp_regs[n] = du;
166 fpu->fp_regs[n + 1] = dl;
167 }
168 }
169
170 /**
171 * ieee_fpe_handler - Handle denormalized number exception
172 *
173 * @regs: Pointer to register structure
174 *
175 * Returns 1 when it's handled (should not cause exception).
176 */
ieee_fpe_handler(struct pt_regs * regs)177 static int ieee_fpe_handler(struct pt_regs *regs)
178 {
179 unsigned short insn = *(unsigned short *)regs->pc;
180 unsigned short finsn;
181 unsigned long nextpc;
182 int nib[4] = {
183 (insn >> 12) & 0xf,
184 (insn >> 8) & 0xf,
185 (insn >> 4) & 0xf,
186 insn & 0xf
187 };
188
189 if (nib[0] == 0xb || (nib[0] == 0x4 && nib[2] == 0x0 && nib[3] == 0xb))
190 regs->pr = regs->pc + 4; /* bsr & jsr */
191
192 if (nib[0] == 0xa || nib[0] == 0xb) {
193 /* bra & bsr */
194 nextpc = regs->pc + 4 + ((short)((insn & 0xfff) << 4) >> 3);
195 finsn = *(unsigned short *)(regs->pc + 2);
196 } else if (nib[0] == 0x8 && nib[1] == 0xd) {
197 /* bt/s */
198 if (regs->sr & 1)
199 nextpc = regs->pc + 4 + ((char)(insn & 0xff) << 1);
200 else
201 nextpc = regs->pc + 4;
202 finsn = *(unsigned short *)(regs->pc + 2);
203 } else if (nib[0] == 0x8 && nib[1] == 0xf) {
204 /* bf/s */
205 if (regs->sr & 1)
206 nextpc = regs->pc + 4;
207 else
208 nextpc = regs->pc + 4 + ((char)(insn & 0xff) << 1);
209 finsn = *(unsigned short *)(regs->pc + 2);
210 } else if (nib[0] == 0x4 && nib[3] == 0xb &&
211 (nib[2] == 0x0 || nib[2] == 0x2)) {
212 /* jmp & jsr */
213 nextpc = regs->regs[nib[1]];
214 finsn = *(unsigned short *)(regs->pc + 2);
215 } else if (nib[0] == 0x0 && nib[3] == 0x3 &&
216 (nib[2] == 0x0 || nib[2] == 0x2)) {
217 /* braf & bsrf */
218 nextpc = regs->pc + 4 + regs->regs[nib[1]];
219 finsn = *(unsigned short *)(regs->pc + 2);
220 } else if (insn == 0x000b) {
221 /* rts */
222 nextpc = regs->pr;
223 finsn = *(unsigned short *)(regs->pc + 2);
224 } else {
225 nextpc = regs->pc + instruction_size(insn);
226 finsn = insn;
227 }
228
229 if ((finsn & 0xf1ff) == 0xf0ad) {
230 /* fcnvsd */
231 struct task_struct *tsk = current;
232
233 if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_CAUSE_ERROR))
234 /* FPU error */
235 denormal_to_double(&tsk->thread.xstate->hardfpu,
236 (finsn >> 8) & 0xf);
237 else
238 return 0;
239
240 regs->pc = nextpc;
241 return 1;
242 } else if ((finsn & 0xf00f) == 0xf002) {
243 /* fmul */
244 struct task_struct *tsk = current;
245 int fpscr;
246 int n, m, prec;
247 unsigned int hx, hy;
248
249 n = (finsn >> 8) & 0xf;
250 m = (finsn >> 4) & 0xf;
251 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
252 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
253 fpscr = tsk->thread.xstate->hardfpu.fpscr;
254 prec = fpscr & FPSCR_DBL_PRECISION;
255
256 if ((fpscr & FPSCR_CAUSE_ERROR)
257 && (prec && ((hx & 0x7fffffff) < 0x00100000
258 || (hy & 0x7fffffff) < 0x00100000))) {
259 long long llx, lly;
260
261 /* FPU error because of denormal (doubles) */
262 llx = ((long long)hx << 32)
263 | tsk->thread.xstate->hardfpu.fp_regs[n + 1];
264 lly = ((long long)hy << 32)
265 | tsk->thread.xstate->hardfpu.fp_regs[m + 1];
266 llx = float64_mul(llx, lly);
267 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
268 tsk->thread.xstate->hardfpu.fp_regs[n + 1] = llx & 0xffffffff;
269 } else if ((fpscr & FPSCR_CAUSE_ERROR)
270 && (!prec && ((hx & 0x7fffffff) < 0x00800000
271 || (hy & 0x7fffffff) < 0x00800000))) {
272 /* FPU error because of denormal (floats) */
273 hx = float32_mul(hx, hy);
274 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
275 } else
276 return 0;
277
278 regs->pc = nextpc;
279 return 1;
280 } else if ((finsn & 0xf00e) == 0xf000) {
281 /* fadd, fsub */
282 struct task_struct *tsk = current;
283 int fpscr;
284 int n, m, prec;
285 unsigned int hx, hy;
286
287 n = (finsn >> 8) & 0xf;
288 m = (finsn >> 4) & 0xf;
289 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
290 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
291 fpscr = tsk->thread.xstate->hardfpu.fpscr;
292 prec = fpscr & FPSCR_DBL_PRECISION;
293
294 if ((fpscr & FPSCR_CAUSE_ERROR)
295 && (prec && ((hx & 0x7fffffff) < 0x00100000
296 || (hy & 0x7fffffff) < 0x00100000))) {
297 long long llx, lly;
298
299 /* FPU error because of denormal (doubles) */
300 llx = ((long long)hx << 32)
301 | tsk->thread.xstate->hardfpu.fp_regs[n + 1];
302 lly = ((long long)hy << 32)
303 | tsk->thread.xstate->hardfpu.fp_regs[m + 1];
304 if ((finsn & 0xf00f) == 0xf000)
305 llx = float64_add(llx, lly);
306 else
307 llx = float64_sub(llx, lly);
308 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
309 tsk->thread.xstate->hardfpu.fp_regs[n + 1] = llx & 0xffffffff;
310 } else if ((fpscr & FPSCR_CAUSE_ERROR)
311 && (!prec && ((hx & 0x7fffffff) < 0x00800000
312 || (hy & 0x7fffffff) < 0x00800000))) {
313 /* FPU error because of denormal (floats) */
314 if ((finsn & 0xf00f) == 0xf000)
315 hx = float32_add(hx, hy);
316 else
317 hx = float32_sub(hx, hy);
318 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
319 } else
320 return 0;
321
322 regs->pc = nextpc;
323 return 1;
324 } else if ((finsn & 0xf003) == 0xf003) {
325 /* fdiv */
326 struct task_struct *tsk = current;
327 int fpscr;
328 int n, m, prec;
329 unsigned int hx, hy;
330
331 n = (finsn >> 8) & 0xf;
332 m = (finsn >> 4) & 0xf;
333 hx = tsk->thread.xstate->hardfpu.fp_regs[n];
334 hy = tsk->thread.xstate->hardfpu.fp_regs[m];
335 fpscr = tsk->thread.xstate->hardfpu.fpscr;
336 prec = fpscr & FPSCR_DBL_PRECISION;
337
338 if ((fpscr & FPSCR_CAUSE_ERROR)
339 && (prec && ((hx & 0x7fffffff) < 0x00100000
340 || (hy & 0x7fffffff) < 0x00100000))) {
341 long long llx, lly;
342
343 /* FPU error because of denormal (doubles) */
344 llx = ((long long)hx << 32)
345 | tsk->thread.xstate->hardfpu.fp_regs[n + 1];
346 lly = ((long long)hy << 32)
347 | tsk->thread.xstate->hardfpu.fp_regs[m + 1];
348
349 llx = float64_div(llx, lly);
350
351 tsk->thread.xstate->hardfpu.fp_regs[n] = llx >> 32;
352 tsk->thread.xstate->hardfpu.fp_regs[n + 1] = llx & 0xffffffff;
353 } else if ((fpscr & FPSCR_CAUSE_ERROR)
354 && (!prec && ((hx & 0x7fffffff) < 0x00800000
355 || (hy & 0x7fffffff) < 0x00800000))) {
356 /* FPU error because of denormal (floats) */
357 hx = float32_div(hx, hy);
358 tsk->thread.xstate->hardfpu.fp_regs[n] = hx;
359 } else
360 return 0;
361
362 regs->pc = nextpc;
363 return 1;
364 } else if ((finsn & 0xf0bd) == 0xf0bd) {
365 /* fcnvds - double to single precision convert */
366 struct task_struct *tsk = current;
367 int m;
368 unsigned int hx;
369
370 m = (finsn >> 8) & 0x7;
371 hx = tsk->thread.xstate->hardfpu.fp_regs[m];
372
373 if ((tsk->thread.xstate->hardfpu.fpscr & FPSCR_CAUSE_ERROR)
374 && ((hx & 0x7fffffff) < 0x00100000)) {
375 /* subnormal double to float conversion */
376 long long llx;
377
378 llx = ((long long)tsk->thread.xstate->hardfpu.fp_regs[m] << 32)
379 | tsk->thread.xstate->hardfpu.fp_regs[m + 1];
380
381 tsk->thread.xstate->hardfpu.fpul = float64_to_float32(llx);
382 } else
383 return 0;
384
385 regs->pc = nextpc;
386 return 1;
387 }
388
389 return 0;
390 }
391
float_raise(unsigned int flags)392 void float_raise(unsigned int flags)
393 {
394 fpu_exception_flags |= flags;
395 }
396
float_rounding_mode(void)397 int float_rounding_mode(void)
398 {
399 struct task_struct *tsk = current;
400 int roundingMode = FPSCR_ROUNDING_MODE(tsk->thread.xstate->hardfpu.fpscr);
401 return roundingMode;
402 }
403
BUILD_TRAP_HANDLER(fpu_error)404 BUILD_TRAP_HANDLER(fpu_error)
405 {
406 struct task_struct *tsk = current;
407 TRAP_HANDLER_DECL;
408
409 __unlazy_fpu(tsk, regs);
410 fpu_exception_flags = 0;
411 if (ieee_fpe_handler(regs)) {
412 tsk->thread.xstate->hardfpu.fpscr &=
413 ~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
414 tsk->thread.xstate->hardfpu.fpscr |= fpu_exception_flags;
415 /* Set the FPSCR flag as well as cause bits - simply
416 * replicate the cause */
417 tsk->thread.xstate->hardfpu.fpscr |= (fpu_exception_flags >> 10);
418 grab_fpu(regs);
419 restore_fpu(tsk);
420 task_thread_info(tsk)->status |= TS_USEDFPU;
421 if ((((tsk->thread.xstate->hardfpu.fpscr & FPSCR_ENABLE_MASK) >> 7) &
422 (fpu_exception_flags >> 2)) == 0) {
423 return;
424 }
425 }
426
427 force_sig(SIGFPE, tsk);
428 }
429
