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-rw-r--r--arch/sh/kernel/cpu/sh4/fpu.c335
1 files changed, 335 insertions, 0 deletions
diff --git a/arch/sh/kernel/cpu/sh4/fpu.c b/arch/sh/kernel/cpu/sh4/fpu.c
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1/* $Id: fpu.c,v 1.4 2004/01/13 05:52:11 kkojima Exp $
2 *
3 * linux/arch/sh/kernel/fpu.c
4 *
5 * Save/restore floating point context for signal handlers.
6 *
7 * This file is subject to the terms and conditions of the GNU General Public
8 * License. See the file "COPYING" in the main directory of this archive
9 * for more details.
10 *
11 * Copyright (C) 1999, 2000 Kaz Kojima & Niibe Yutaka
12 *
13 * FIXME! These routines can be optimized in big endian case.
14 */
15
16#include <linux/sched.h>
17#include <linux/signal.h>
18#include <asm/processor.h>
19#include <asm/io.h>
20
21/* The PR (precision) bit in the FP Status Register must be clear when
22 * an frchg instruction is executed, otherwise the instruction is undefined.
23 * Executing frchg with PR set causes a trap on some SH4 implementations.
24 */
25
26#define FPSCR_RCHG 0x00000000
27
28
29/*
30 * Save FPU registers onto task structure.
31 * Assume called with FPU enabled (SR.FD=0).
32 */
33void
34save_fpu(struct task_struct *tsk, struct pt_regs *regs)
35{
36 unsigned long dummy;
37
38 clear_tsk_thread_flag(tsk, TIF_USEDFPU);
39 enable_fpu();
40 asm volatile("sts.l fpul, @-%0\n\t"
41 "sts.l fpscr, @-%0\n\t"
42 "lds %2, fpscr\n\t"
43 "frchg\n\t"
44 "fmov.s fr15, @-%0\n\t"
45 "fmov.s fr14, @-%0\n\t"
46 "fmov.s fr13, @-%0\n\t"
47 "fmov.s fr12, @-%0\n\t"
48 "fmov.s fr11, @-%0\n\t"
49 "fmov.s fr10, @-%0\n\t"
50 "fmov.s fr9, @-%0\n\t"
51 "fmov.s fr8, @-%0\n\t"
52 "fmov.s fr7, @-%0\n\t"
53 "fmov.s fr6, @-%0\n\t"
54 "fmov.s fr5, @-%0\n\t"
55 "fmov.s fr4, @-%0\n\t"
56 "fmov.s fr3, @-%0\n\t"
57 "fmov.s fr2, @-%0\n\t"
58 "fmov.s fr1, @-%0\n\t"
59 "fmov.s fr0, @-%0\n\t"
60 "frchg\n\t"
61 "fmov.s fr15, @-%0\n\t"
62 "fmov.s fr14, @-%0\n\t"
63 "fmov.s fr13, @-%0\n\t"
64 "fmov.s fr12, @-%0\n\t"
65 "fmov.s fr11, @-%0\n\t"
66 "fmov.s fr10, @-%0\n\t"
67 "fmov.s fr9, @-%0\n\t"
68 "fmov.s fr8, @-%0\n\t"
69 "fmov.s fr7, @-%0\n\t"
70 "fmov.s fr6, @-%0\n\t"
71 "fmov.s fr5, @-%0\n\t"
72 "fmov.s fr4, @-%0\n\t"
73 "fmov.s fr3, @-%0\n\t"
74 "fmov.s fr2, @-%0\n\t"
75 "fmov.s fr1, @-%0\n\t"
76 "fmov.s fr0, @-%0\n\t"
77 "lds %3, fpscr\n\t"
78 : "=r" (dummy)
79 : "0" ((char *)(&tsk->thread.fpu.hard.status)),
80 "r" (FPSCR_RCHG),
81 "r" (FPSCR_INIT)
82 : "memory");
83
84 disable_fpu();
85 release_fpu(regs);
86}
87
88static void
89restore_fpu(struct task_struct *tsk)
90{
91 unsigned long dummy;
92
93 enable_fpu();
94 asm volatile("lds %2, fpscr\n\t"
95 "fmov.s @%0+, fr0\n\t"
96 "fmov.s @%0+, fr1\n\t"
97 "fmov.s @%0+, fr2\n\t"
98 "fmov.s @%0+, fr3\n\t"
99 "fmov.s @%0+, fr4\n\t"
100 "fmov.s @%0+, fr5\n\t"
101 "fmov.s @%0+, fr6\n\t"
102 "fmov.s @%0+, fr7\n\t"
103 "fmov.s @%0+, fr8\n\t"
104 "fmov.s @%0+, fr9\n\t"
105 "fmov.s @%0+, fr10\n\t"
106 "fmov.s @%0+, fr11\n\t"
107 "fmov.s @%0+, fr12\n\t"
108 "fmov.s @%0+, fr13\n\t"
109 "fmov.s @%0+, fr14\n\t"
110 "fmov.s @%0+, fr15\n\t"
111 "frchg\n\t"
112 "fmov.s @%0+, fr0\n\t"
113 "fmov.s @%0+, fr1\n\t"
114 "fmov.s @%0+, fr2\n\t"
115 "fmov.s @%0+, fr3\n\t"
116 "fmov.s @%0+, fr4\n\t"
117 "fmov.s @%0+, fr5\n\t"
118 "fmov.s @%0+, fr6\n\t"
119 "fmov.s @%0+, fr7\n\t"
120 "fmov.s @%0+, fr8\n\t"
121 "fmov.s @%0+, fr9\n\t"
122 "fmov.s @%0+, fr10\n\t"
123 "fmov.s @%0+, fr11\n\t"
124 "fmov.s @%0+, fr12\n\t"
125 "fmov.s @%0+, fr13\n\t"
126 "fmov.s @%0+, fr14\n\t"
127 "fmov.s @%0+, fr15\n\t"
128 "frchg\n\t"
129 "lds.l @%0+, fpscr\n\t"
130 "lds.l @%0+, fpul\n\t"
131 : "=r" (dummy)
132 : "0" (&tsk->thread.fpu), "r" (FPSCR_RCHG)
133 : "memory");
134 disable_fpu();
135}
136
137/*
138 * Load the FPU with signalling NANS. This bit pattern we're using
139 * has the property that no matter wether considered as single or as
140 * double precission represents signaling NANS.
141 */
142
143static void
144fpu_init(void)
145{
146 enable_fpu();
147 asm volatile("lds %0, fpul\n\t"
148 "lds %1, fpscr\n\t"
149 "fsts fpul, fr0\n\t"
150 "fsts fpul, fr1\n\t"
151 "fsts fpul, fr2\n\t"
152 "fsts fpul, fr3\n\t"
153 "fsts fpul, fr4\n\t"
154 "fsts fpul, fr5\n\t"
155 "fsts fpul, fr6\n\t"
156 "fsts fpul, fr7\n\t"
157 "fsts fpul, fr8\n\t"
158 "fsts fpul, fr9\n\t"
159 "fsts fpul, fr10\n\t"
160 "fsts fpul, fr11\n\t"
161 "fsts fpul, fr12\n\t"
162 "fsts fpul, fr13\n\t"
163 "fsts fpul, fr14\n\t"
164 "fsts fpul, fr15\n\t"
165 "frchg\n\t"
166 "fsts fpul, fr0\n\t"
167 "fsts fpul, fr1\n\t"
168 "fsts fpul, fr2\n\t"
169 "fsts fpul, fr3\n\t"
170 "fsts fpul, fr4\n\t"
171 "fsts fpul, fr5\n\t"
172 "fsts fpul, fr6\n\t"
173 "fsts fpul, fr7\n\t"
174 "fsts fpul, fr8\n\t"
175 "fsts fpul, fr9\n\t"
176 "fsts fpul, fr10\n\t"
177 "fsts fpul, fr11\n\t"
178 "fsts fpul, fr12\n\t"
179 "fsts fpul, fr13\n\t"
180 "fsts fpul, fr14\n\t"
181 "fsts fpul, fr15\n\t"
182 "frchg\n\t"
183 "lds %2, fpscr\n\t"
184 : /* no output */
185 : "r" (0), "r" (FPSCR_RCHG), "r" (FPSCR_INIT));
186 disable_fpu();
187}
188
189/**
190 * denormal_to_double - Given denormalized float number,
191 * store double float
192 *
193 * @fpu: Pointer to sh_fpu_hard structure
194 * @n: Index to FP register
195 */
196static void
197denormal_to_double (struct sh_fpu_hard_struct *fpu, int n)
198{
199 unsigned long du, dl;
200 unsigned long x = fpu->fpul;
201 int exp = 1023 - 126;
202
203 if (x != 0 && (x & 0x7f800000) == 0) {
204 du = (x & 0x80000000);
205 while ((x & 0x00800000) == 0) {
206 x <<= 1;
207 exp--;
208 }
209 x &= 0x007fffff;
210 du |= (exp << 20) | (x >> 3);
211 dl = x << 29;
212
213 fpu->fp_regs[n] = du;
214 fpu->fp_regs[n+1] = dl;
215 }
216}
217
218/**
219 * ieee_fpe_handler - Handle denormalized number exception
220 *
221 * @regs: Pointer to register structure
222 *
223 * Returns 1 when it's handled (should not cause exception).
224 */
225static int
226ieee_fpe_handler (struct pt_regs *regs)
227{
228 unsigned short insn = *(unsigned short *) regs->pc;
229 unsigned short finsn;
230 unsigned long nextpc;
231 int nib[4] = {
232 (insn >> 12) & 0xf,
233 (insn >> 8) & 0xf,
234 (insn >> 4) & 0xf,
235 insn & 0xf};
236
237 if (nib[0] == 0xb ||
238 (nib[0] == 0x4 && nib[2] == 0x0 && nib[3] == 0xb)) /* bsr & jsr */
239 regs->pr = regs->pc + 4;
240
241 if (nib[0] == 0xa || nib[0] == 0xb) { /* bra & bsr */
242 nextpc = regs->pc + 4 + ((short) ((insn & 0xfff) << 4) >> 3);
243 finsn = *(unsigned short *) (regs->pc + 2);
244 } else if (nib[0] == 0x8 && nib[1] == 0xd) { /* bt/s */
245 if (regs->sr & 1)
246 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
247 else
248 nextpc = regs->pc + 4;
249 finsn = *(unsigned short *) (regs->pc + 2);
250 } else if (nib[0] == 0x8 && nib[1] == 0xf) { /* bf/s */
251 if (regs->sr & 1)
252 nextpc = regs->pc + 4;
253 else
254 nextpc = regs->pc + 4 + ((char) (insn & 0xff) << 1);
255 finsn = *(unsigned short *) (regs->pc + 2);
256 } else if (nib[0] == 0x4 && nib[3] == 0xb &&
257 (nib[2] == 0x0 || nib[2] == 0x2)) { /* jmp & jsr */
258 nextpc = regs->regs[nib[1]];
259 finsn = *(unsigned short *) (regs->pc + 2);
260 } else if (nib[0] == 0x0 && nib[3] == 0x3 &&
261 (nib[2] == 0x0 || nib[2] == 0x2)) { /* braf & bsrf */
262 nextpc = regs->pc + 4 + regs->regs[nib[1]];
263 finsn = *(unsigned short *) (regs->pc + 2);
264 } else if (insn == 0x000b) { /* rts */
265 nextpc = regs->pr;
266 finsn = *(unsigned short *) (regs->pc + 2);
267 } else {
268 nextpc = regs->pc + 2;
269 finsn = insn;
270 }
271
272 if ((finsn & 0xf1ff) == 0xf0ad) { /* fcnvsd */
273 struct task_struct *tsk = current;
274
275 save_fpu(tsk, regs);
276 if ((tsk->thread.fpu.hard.fpscr & (1 << 17))) {
277 /* FPU error */
278 denormal_to_double (&tsk->thread.fpu.hard,
279 (finsn >> 8) & 0xf);
280 tsk->thread.fpu.hard.fpscr &=
281 ~(FPSCR_CAUSE_MASK | FPSCR_FLAG_MASK);
282 grab_fpu(regs);
283 restore_fpu(tsk);
284 set_tsk_thread_flag(tsk, TIF_USEDFPU);
285 } else {
286 tsk->thread.trap_no = 11;
287 tsk->thread.error_code = 0;
288 force_sig(SIGFPE, tsk);
289 }
290
291 regs->pc = nextpc;
292 return 1;
293 }
294
295 return 0;
296}
297
298asmlinkage void
299do_fpu_error(unsigned long r4, unsigned long r5, unsigned long r6, unsigned long r7,
300 struct pt_regs regs)
301{
302 struct task_struct *tsk = current;
303
304 if (ieee_fpe_handler (&regs))
305 return;
306
307 regs.pc += 2;
308 save_fpu(tsk, &regs);
309 tsk->thread.trap_no = 11;
310 tsk->thread.error_code = 0;
311 force_sig(SIGFPE, tsk);
312}
313
314asmlinkage void
315do_fpu_state_restore(unsigned long r4, unsigned long r5, unsigned long r6,
316 unsigned long r7, struct pt_regs regs)
317{
318 struct task_struct *tsk = current;
319
320 grab_fpu(&regs);
321 if (!user_mode(&regs)) {
322 printk(KERN_ERR "BUG: FPU is used in kernel mode.\n");
323 return;
324 }
325
326 if (used_math()) {
327 /* Using the FPU again. */
328 restore_fpu(tsk);
329 } else {
330 /* First time FPU user. */
331 fpu_init();
332 set_used_math();
333 }
334 set_tsk_thread_flag(tsk, TIF_USEDFPU);
335}
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