1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/module.h>
3 #include <linux/types.h>
4 #include <linux/kernel.h>
5 #include <linux/sched.h>
6 #include <asm/ptrace.h>
7 #include <asm/fpu.h>
8
9 #include <linux/uaccess.h>
10
11 #include "sfp-util.h"
12 #include <math-emu/soft-fp.h>
13 #include <math-emu/single.h>
14 #include <math-emu/double.h>
15
16 #define OPC_PAL 0x00
17 #define OPC_INTA 0x10
18 #define OPC_INTL 0x11
19 #define OPC_INTS 0x12
20 #define OPC_INTM 0x13
21 #define OPC_FLTC 0x14
22 #define OPC_FLTV 0x15
23 #define OPC_FLTI 0x16
24 #define OPC_FLTL 0x17
25 #define OPC_MISC 0x18
26 #define OPC_JSR 0x1a
27
28 #define FOP_SRC_S 0
29 #define FOP_SRC_T 2
30 #define FOP_SRC_Q 3
31
32 #define FOP_FNC_ADDx 0
33 #define FOP_FNC_CVTQL 0
34 #define FOP_FNC_SUBx 1
35 #define FOP_FNC_MULx 2
36 #define FOP_FNC_DIVx 3
37 #define FOP_FNC_CMPxUN 4
38 #define FOP_FNC_CMPxEQ 5
39 #define FOP_FNC_CMPxLT 6
40 #define FOP_FNC_CMPxLE 7
41 #define FOP_FNC_SQRTx 11
42 #define FOP_FNC_CVTxS 12
43 #define FOP_FNC_CVTxT 14
44 #define FOP_FNC_CVTxQ 15
45
46 #define MISC_TRAPB 0x0000
47 #define MISC_EXCB 0x0400
48
49 #ifdef MODULE
50
51 MODULE_DESCRIPTION("FP Software completion module");
52 MODULE_LICENSE("GPL v2");
53
54 extern long (*alpha_fp_emul_imprecise)(struct pt_regs *, unsigned long);
55 extern long (*alpha_fp_emul) (unsigned long pc);
56
57 static long (*save_emul_imprecise)(struct pt_regs *, unsigned long);
58 static long (*save_emul) (unsigned long pc);
59
60 long do_alpha_fp_emul_imprecise(struct pt_regs *, unsigned long);
61 long do_alpha_fp_emul(unsigned long);
62
alpha_fp_emul_init_module(void)63 static int alpha_fp_emul_init_module(void)
64 {
65 save_emul_imprecise = alpha_fp_emul_imprecise;
66 save_emul = alpha_fp_emul;
67 alpha_fp_emul_imprecise = do_alpha_fp_emul_imprecise;
68 alpha_fp_emul = do_alpha_fp_emul;
69 return 0;
70 }
71 module_init(alpha_fp_emul_init_module);
72
alpha_fp_emul_cleanup_module(void)73 static void alpha_fp_emul_cleanup_module(void)
74 {
75 alpha_fp_emul_imprecise = save_emul_imprecise;
76 alpha_fp_emul = save_emul;
77 }
78 module_exit(alpha_fp_emul_cleanup_module);
79
80 #undef alpha_fp_emul_imprecise
81 #define alpha_fp_emul_imprecise do_alpha_fp_emul_imprecise
82 #undef alpha_fp_emul
83 #define alpha_fp_emul do_alpha_fp_emul
84
85 #endif /* MODULE */
86
87
88 /*
89 * Emulate the floating point instruction at address PC. Returns -1 if the
90 * instruction to be emulated is illegal (such as with the opDEC trap), else
91 * the SI_CODE for a SIGFPE signal, else 0 if everything's ok.
92 *
93 * Notice that the kernel does not and cannot use FP regs. This is good
94 * because it means that instead of saving/restoring all fp regs, we simply
95 * stick the result of the operation into the appropriate register.
96 */
97 long
alpha_fp_emul(unsigned long pc)98 alpha_fp_emul (unsigned long pc)
99 {
100 FP_DECL_EX;
101 FP_DECL_S(SA); FP_DECL_S(SB); FP_DECL_S(SR);
102 FP_DECL_D(DA); FP_DECL_D(DB); FP_DECL_D(DR);
103
104 unsigned long fa, fb, fc, func, mode, src;
105 unsigned long res, va, vb, vc, swcr, fpcr;
106 __u32 insn;
107 long si_code;
108
109 get_user(insn, (__u32 __user *)pc);
110 fc = (insn >> 0) & 0x1f; /* destination register */
111 fb = (insn >> 16) & 0x1f;
112 fa = (insn >> 21) & 0x1f;
113 func = (insn >> 5) & 0xf;
114 src = (insn >> 9) & 0x3;
115 mode = (insn >> 11) & 0x3;
116
117 fpcr = rdfpcr();
118 swcr = swcr_update_status(current_thread_info()->ieee_state, fpcr);
119
120 if (mode == 3) {
121 /* Dynamic -- get rounding mode from fpcr. */
122 mode = (fpcr >> FPCR_DYN_SHIFT) & 3;
123 }
124
125 switch (src) {
126 case FOP_SRC_S:
127 va = alpha_read_fp_reg_s(fa);
128 vb = alpha_read_fp_reg_s(fb);
129
130 FP_UNPACK_SP(SA, &va);
131 FP_UNPACK_SP(SB, &vb);
132
133 switch (func) {
134 case FOP_FNC_SUBx:
135 FP_SUB_S(SR, SA, SB);
136 goto pack_s;
137
138 case FOP_FNC_ADDx:
139 FP_ADD_S(SR, SA, SB);
140 goto pack_s;
141
142 case FOP_FNC_MULx:
143 FP_MUL_S(SR, SA, SB);
144 goto pack_s;
145
146 case FOP_FNC_DIVx:
147 FP_DIV_S(SR, SA, SB);
148 goto pack_s;
149
150 case FOP_FNC_SQRTx:
151 FP_SQRT_S(SR, SB);
152 goto pack_s;
153 }
154 goto bad_insn;
155
156 case FOP_SRC_T:
157 va = alpha_read_fp_reg(fa);
158 vb = alpha_read_fp_reg(fb);
159
160 if ((func & ~3) == FOP_FNC_CMPxUN) {
161 FP_UNPACK_RAW_DP(DA, &va);
162 FP_UNPACK_RAW_DP(DB, &vb);
163 if (!DA_e && !_FP_FRAC_ZEROP_1(DA)) {
164 FP_SET_EXCEPTION(FP_EX_DENORM);
165 if (FP_DENORM_ZERO)
166 _FP_FRAC_SET_1(DA, _FP_ZEROFRAC_1);
167 }
168 if (!DB_e && !_FP_FRAC_ZEROP_1(DB)) {
169 FP_SET_EXCEPTION(FP_EX_DENORM);
170 if (FP_DENORM_ZERO)
171 _FP_FRAC_SET_1(DB, _FP_ZEROFRAC_1);
172 }
173 FP_CMP_D(res, DA, DB, 3);
174 vc = 0x4000000000000000UL;
175 /* CMPTEQ, CMPTUN don't trap on QNaN,
176 while CMPTLT and CMPTLE do */
177 if (res == 3
178 && ((func & 3) >= 2
179 || FP_ISSIGNAN_D(DA)
180 || FP_ISSIGNAN_D(DB))) {
181 FP_SET_EXCEPTION(FP_EX_INVALID);
182 }
183 switch (func) {
184 case FOP_FNC_CMPxUN: if (res != 3) vc = 0; break;
185 case FOP_FNC_CMPxEQ: if (res) vc = 0; break;
186 case FOP_FNC_CMPxLT: if (res != -1) vc = 0; break;
187 case FOP_FNC_CMPxLE: if ((long)res > 0) vc = 0; break;
188 }
189 goto done_d;
190 }
191
192 FP_UNPACK_DP(DA, &va);
193 FP_UNPACK_DP(DB, &vb);
194
195 switch (func) {
196 case FOP_FNC_SUBx:
197 FP_SUB_D(DR, DA, DB);
198 goto pack_d;
199
200 case FOP_FNC_ADDx:
201 FP_ADD_D(DR, DA, DB);
202 goto pack_d;
203
204 case FOP_FNC_MULx:
205 FP_MUL_D(DR, DA, DB);
206 goto pack_d;
207
208 case FOP_FNC_DIVx:
209 FP_DIV_D(DR, DA, DB);
210 goto pack_d;
211
212 case FOP_FNC_SQRTx:
213 FP_SQRT_D(DR, DB);
214 goto pack_d;
215
216 case FOP_FNC_CVTxS:
217 /* It is irritating that DEC encoded CVTST with
218 SRC == T_floating. It is also interesting that
219 the bit used to tell the two apart is /U... */
220 if (insn & 0x2000) {
221 FP_CONV(S,D,1,1,SR,DB);
222 goto pack_s;
223 } else {
224 vb = alpha_read_fp_reg_s(fb);
225 FP_UNPACK_SP(SB, &vb);
226 DR_c = DB_c;
227 DR_s = DB_s;
228 DR_e = DB_e + (1024 - 128);
229 DR_f = SB_f << (52 - 23);
230 goto pack_d;
231 }
232
233 case FOP_FNC_CVTxQ:
234 if (DB_c == FP_CLS_NAN
235 && (_FP_FRAC_HIGH_RAW_D(DB) & _FP_QNANBIT_D)) {
236 /* AAHB Table B-2 says QNaN should not trigger INV */
237 vc = 0;
238 } else
239 FP_TO_INT_ROUND_D(vc, DB, 64, 2);
240 goto done_d;
241 }
242 goto bad_insn;
243
244 case FOP_SRC_Q:
245 vb = alpha_read_fp_reg(fb);
246
247 switch (func) {
248 case FOP_FNC_CVTQL:
249 /* Notice: We can get here only due to an integer
250 overflow. Such overflows are reported as invalid
251 ops. We return the result the hw would have
252 computed. */
253 vc = ((vb & 0xc0000000) << 32 | /* sign and msb */
254 (vb & 0x3fffffff) << 29); /* rest of the int */
255 FP_SET_EXCEPTION (FP_EX_INVALID);
256 goto done_d;
257
258 case FOP_FNC_CVTxS:
259 FP_FROM_INT_S(SR, ((long)vb), 64, long);
260 goto pack_s;
261
262 case FOP_FNC_CVTxT:
263 FP_FROM_INT_D(DR, ((long)vb), 64, long);
264 goto pack_d;
265 }
266 goto bad_insn;
267 }
268 goto bad_insn;
269
270 pack_s:
271 FP_PACK_SP(&vc, SR);
272 if ((_fex & FP_EX_UNDERFLOW) && (swcr & IEEE_MAP_UMZ))
273 vc = 0;
274 alpha_write_fp_reg_s(fc, vc);
275 goto done;
276
277 pack_d:
278 FP_PACK_DP(&vc, DR);
279 if ((_fex & FP_EX_UNDERFLOW) && (swcr & IEEE_MAP_UMZ))
280 vc = 0;
281 done_d:
282 alpha_write_fp_reg(fc, vc);
283 goto done;
284
285 /*
286 * Take the appropriate action for each possible
287 * floating-point result:
288 *
289 * - Set the appropriate bits in the FPCR
290 * - If the specified exception is enabled in the FPCR,
291 * return. The caller (entArith) will dispatch
292 * the appropriate signal to the translated program.
293 *
294 * In addition, properly track the exception state in software
295 * as described in the Alpha Architecture Handbook section 4.7.7.3.
296 */
297 done:
298 if (_fex) {
299 /* Record exceptions in software control word. */
300 swcr |= (_fex << IEEE_STATUS_TO_EXCSUM_SHIFT);
301 current_thread_info()->ieee_state
302 |= (_fex << IEEE_STATUS_TO_EXCSUM_SHIFT);
303
304 /* Update hardware control register. */
305 fpcr &= (~FPCR_MASK | FPCR_DYN_MASK);
306 fpcr |= ieee_swcr_to_fpcr(swcr);
307 wrfpcr(fpcr);
308
309 /* Do we generate a signal? */
310 _fex = _fex & swcr & IEEE_TRAP_ENABLE_MASK;
311 si_code = 0;
312 if (_fex) {
313 if (_fex & IEEE_TRAP_ENABLE_DNO) si_code = FPE_FLTUND;
314 if (_fex & IEEE_TRAP_ENABLE_INE) si_code = FPE_FLTRES;
315 if (_fex & IEEE_TRAP_ENABLE_UNF) si_code = FPE_FLTUND;
316 if (_fex & IEEE_TRAP_ENABLE_OVF) si_code = FPE_FLTOVF;
317 if (_fex & IEEE_TRAP_ENABLE_DZE) si_code = FPE_FLTDIV;
318 if (_fex & IEEE_TRAP_ENABLE_INV) si_code = FPE_FLTINV;
319 }
320
321 return si_code;
322 }
323
324 /* We used to write the destination register here, but DEC FORTRAN
325 requires that the result *always* be written... so we do the write
326 immediately after the operations above. */
327
328 return 0;
329
330 bad_insn:
331 printk(KERN_ERR "alpha_fp_emul: Invalid FP insn %#x at %#lx\n",
332 insn, pc);
333 return -1;
334 }
335
336 long
alpha_fp_emul_imprecise(struct pt_regs * regs,unsigned long write_mask)337 alpha_fp_emul_imprecise (struct pt_regs *regs, unsigned long write_mask)
338 {
339 unsigned long trigger_pc = regs->pc - 4;
340 unsigned long insn, opcode, rc, si_code = 0;
341
342 /*
343 * Turn off the bits corresponding to registers that are the
344 * target of instructions that set bits in the exception
345 * summary register. We have some slack doing this because a
346 * register that is the target of a trapping instruction can
347 * be written at most once in the trap shadow.
348 *
349 * Branches, jumps, TRAPBs, EXCBs and calls to PALcode all
350 * bound the trap shadow, so we need not look any further than
351 * up to the first occurrence of such an instruction.
352 */
353 while (write_mask) {
354 get_user(insn, (__u32 __user *)(trigger_pc));
355 opcode = insn >> 26;
356 rc = insn & 0x1f;
357
358 switch (opcode) {
359 case OPC_PAL:
360 case OPC_JSR:
361 case 0x30 ... 0x3f: /* branches */
362 goto egress;
363
364 case OPC_MISC:
365 switch (insn & 0xffff) {
366 case MISC_TRAPB:
367 case MISC_EXCB:
368 goto egress;
369
370 default:
371 break;
372 }
373 break;
374
375 case OPC_INTA:
376 case OPC_INTL:
377 case OPC_INTS:
378 case OPC_INTM:
379 write_mask &= ~(1UL << rc);
380 break;
381
382 case OPC_FLTC:
383 case OPC_FLTV:
384 case OPC_FLTI:
385 case OPC_FLTL:
386 write_mask &= ~(1UL << (rc + 32));
387 break;
388 }
389 if (!write_mask) {
390 /* Re-execute insns in the trap-shadow. */
391 regs->pc = trigger_pc + 4;
392 si_code = alpha_fp_emul(trigger_pc);
393 goto egress;
394 }
395 trigger_pc -= 4;
396 }
397
398 egress:
399 return si_code;
400 }
401