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 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 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 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 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