1 /* 2 * linux/arch/arm/vfp/vfpmodule.c 3 * 4 * Copyright (C) 2004 ARM Limited. 5 * Written by Deep Blue Solutions Limited. 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 #include <linux/module.h> 12 #include <linux/types.h> 13 #include <linux/cpu.h> 14 #include <linux/kernel.h> 15 #include <linux/notifier.h> 16 #include <linux/signal.h> 17 #include <linux/sched.h> 18 #include <linux/smp.h> 19 #include <linux/init.h> 20 21 #include <asm/cputype.h> 22 #include <asm/thread_notify.h> 23 #include <asm/vfp.h> 24 25 #include "vfpinstr.h" 26 #include "vfp.h" 27 28 /* 29 * Our undef handlers (in entry.S) 30 */ 31 void vfp_testing_entry(void); 32 void vfp_support_entry(void); 33 void vfp_null_entry(void); 34 35 void (*vfp_vector)(void) = vfp_null_entry; 36 37 /* 38 * Dual-use variable. 39 * Used in startup: set to non-zero if VFP checks fail 40 * After startup, holds VFP architecture 41 */ 42 unsigned int VFP_arch; 43 44 /* 45 * The pointer to the vfpstate structure of the thread which currently 46 * owns the context held in the VFP hardware, or NULL if the hardware 47 * context is invalid. 48 * 49 * For UP, this is sufficient to tell which thread owns the VFP context. 50 * However, for SMP, we also need to check the CPU number stored in the 51 * saved state too to catch migrations. 52 */ 53 union vfp_state *vfp_current_hw_state[NR_CPUS]; 54 55 /* 56 * Is 'thread's most up to date state stored in this CPUs hardware? 57 * Must be called from non-preemptible context. 58 */ 59 static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread) 60 { 61 #ifdef CONFIG_SMP 62 if (thread->vfpstate.hard.cpu != cpu) 63 return false; 64 #endif 65 return vfp_current_hw_state[cpu] == &thread->vfpstate; 66 } 67 68 /* 69 * Force a reload of the VFP context from the thread structure. We do 70 * this by ensuring that access to the VFP hardware is disabled, and 71 * clear last_VFP_context. Must be called from non-preemptible context. 72 */ 73 static void vfp_force_reload(unsigned int cpu, struct thread_info *thread) 74 { 75 if (vfp_state_in_hw(cpu, thread)) { 76 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 77 vfp_current_hw_state[cpu] = NULL; 78 } 79 #ifdef CONFIG_SMP 80 thread->vfpstate.hard.cpu = NR_CPUS; 81 #endif 82 } 83 84 /* 85 * Per-thread VFP initialization. 86 */ 87 static void vfp_thread_flush(struct thread_info *thread) 88 { 89 union vfp_state *vfp = &thread->vfpstate; 90 unsigned int cpu; 91 92 /* 93 * Disable VFP to ensure we initialize it first. We must ensure 94 * that the modification of vfp_current_hw_state[] and hardware 95 * disable are done for the same CPU and without preemption. 96 * 97 * Do this first to ensure that preemption won't overwrite our 98 * state saving should access to the VFP be enabled at this point. 99 */ 100 cpu = get_cpu(); 101 if (vfp_current_hw_state[cpu] == vfp) 102 vfp_current_hw_state[cpu] = NULL; 103 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 104 put_cpu(); 105 106 memset(vfp, 0, sizeof(union vfp_state)); 107 108 vfp->hard.fpexc = FPEXC_EN; 109 vfp->hard.fpscr = FPSCR_ROUND_NEAREST; 110 #ifdef CONFIG_SMP 111 vfp->hard.cpu = NR_CPUS; 112 #endif 113 } 114 115 static void vfp_thread_exit(struct thread_info *thread) 116 { 117 /* release case: Per-thread VFP cleanup. */ 118 union vfp_state *vfp = &thread->vfpstate; 119 unsigned int cpu = get_cpu(); 120 121 if (vfp_current_hw_state[cpu] == vfp) 122 vfp_current_hw_state[cpu] = NULL; 123 put_cpu(); 124 } 125 126 static void vfp_thread_copy(struct thread_info *thread) 127 { 128 struct thread_info *parent = current_thread_info(); 129 130 vfp_sync_hwstate(parent); 131 thread->vfpstate = parent->vfpstate; 132 #ifdef CONFIG_SMP 133 thread->vfpstate.hard.cpu = NR_CPUS; 134 #endif 135 } 136 137 /* 138 * When this function is called with the following 'cmd's, the following 139 * is true while this function is being run: 140 * THREAD_NOFTIFY_SWTICH: 141 * - the previously running thread will not be scheduled onto another CPU. 142 * - the next thread to be run (v) will not be running on another CPU. 143 * - thread->cpu is the local CPU number 144 * - not preemptible as we're called in the middle of a thread switch 145 * THREAD_NOTIFY_FLUSH: 146 * - the thread (v) will be running on the local CPU, so 147 * v === current_thread_info() 148 * - thread->cpu is the local CPU number at the time it is accessed, 149 * but may change at any time. 150 * - we could be preempted if tree preempt rcu is enabled, so 151 * it is unsafe to use thread->cpu. 152 * THREAD_NOTIFY_EXIT 153 * - the thread (v) will be running on the local CPU, so 154 * v === current_thread_info() 155 * - thread->cpu is the local CPU number at the time it is accessed, 156 * but may change at any time. 157 * - we could be preempted if tree preempt rcu is enabled, so 158 * it is unsafe to use thread->cpu. 159 */ 160 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v) 161 { 162 struct thread_info *thread = v; 163 u32 fpexc; 164 #ifdef CONFIG_SMP 165 unsigned int cpu; 166 #endif 167 168 switch (cmd) { 169 case THREAD_NOTIFY_SWITCH: 170 fpexc = fmrx(FPEXC); 171 172 #ifdef CONFIG_SMP 173 cpu = thread->cpu; 174 175 /* 176 * On SMP, if VFP is enabled, save the old state in 177 * case the thread migrates to a different CPU. The 178 * restoring is done lazily. 179 */ 180 if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) 181 vfp_save_state(vfp_current_hw_state[cpu], fpexc); 182 #endif 183 184 /* 185 * Always disable VFP so we can lazily save/restore the 186 * old state. 187 */ 188 fmxr(FPEXC, fpexc & ~FPEXC_EN); 189 break; 190 191 case THREAD_NOTIFY_FLUSH: 192 vfp_thread_flush(thread); 193 break; 194 195 case THREAD_NOTIFY_EXIT: 196 vfp_thread_exit(thread); 197 break; 198 199 case THREAD_NOTIFY_COPY: 200 vfp_thread_copy(thread); 201 break; 202 } 203 204 return NOTIFY_DONE; 205 } 206 207 static struct notifier_block vfp_notifier_block = { 208 .notifier_call = vfp_notifier, 209 }; 210 211 /* 212 * Raise a SIGFPE for the current process. 213 * sicode describes the signal being raised. 214 */ 215 static void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs) 216 { 217 siginfo_t info; 218 219 memset(&info, 0, sizeof(info)); 220 221 info.si_signo = SIGFPE; 222 info.si_code = sicode; 223 info.si_addr = (void __user *)(instruction_pointer(regs) - 4); 224 225 /* 226 * This is the same as NWFPE, because it's not clear what 227 * this is used for 228 */ 229 current->thread.error_code = 0; 230 current->thread.trap_no = 6; 231 232 send_sig_info(SIGFPE, &info, current); 233 } 234 235 static void vfp_panic(char *reason, u32 inst) 236 { 237 int i; 238 239 printk(KERN_ERR "VFP: Error: %s\n", reason); 240 printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n", 241 fmrx(FPEXC), fmrx(FPSCR), inst); 242 for (i = 0; i < 32; i += 2) 243 printk(KERN_ERR "VFP: s%2u: 0x%08x s%2u: 0x%08x\n", 244 i, vfp_get_float(i), i+1, vfp_get_float(i+1)); 245 } 246 247 /* 248 * Process bitmask of exception conditions. 249 */ 250 static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs) 251 { 252 int si_code = 0; 253 254 pr_debug("VFP: raising exceptions %08x\n", exceptions); 255 256 if (exceptions == VFP_EXCEPTION_ERROR) { 257 vfp_panic("unhandled bounce", inst); 258 vfp_raise_sigfpe(0, regs); 259 return; 260 } 261 262 /* 263 * If any of the status flags are set, update the FPSCR. 264 * Comparison instructions always return at least one of 265 * these flags set. 266 */ 267 if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V)) 268 fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V); 269 270 fpscr |= exceptions; 271 272 fmxr(FPSCR, fpscr); 273 274 #define RAISE(stat,en,sig) \ 275 if (exceptions & stat && fpscr & en) \ 276 si_code = sig; 277 278 /* 279 * These are arranged in priority order, least to highest. 280 */ 281 RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV); 282 RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES); 283 RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND); 284 RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF); 285 RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV); 286 287 if (si_code) 288 vfp_raise_sigfpe(si_code, regs); 289 } 290 291 /* 292 * Emulate a VFP instruction. 293 */ 294 static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs) 295 { 296 u32 exceptions = VFP_EXCEPTION_ERROR; 297 298 pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr); 299 300 if (INST_CPRTDO(inst)) { 301 if (!INST_CPRT(inst)) { 302 /* 303 * CPDO 304 */ 305 if (vfp_single(inst)) { 306 exceptions = vfp_single_cpdo(inst, fpscr); 307 } else { 308 exceptions = vfp_double_cpdo(inst, fpscr); 309 } 310 } else { 311 /* 312 * A CPRT instruction can not appear in FPINST2, nor 313 * can it cause an exception. Therefore, we do not 314 * have to emulate it. 315 */ 316 } 317 } else { 318 /* 319 * A CPDT instruction can not appear in FPINST2, nor can 320 * it cause an exception. Therefore, we do not have to 321 * emulate it. 322 */ 323 } 324 return exceptions & ~VFP_NAN_FLAG; 325 } 326 327 /* 328 * Package up a bounce condition. 329 */ 330 void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) 331 { 332 u32 fpscr, orig_fpscr, fpsid, exceptions; 333 334 pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc); 335 336 /* 337 * At this point, FPEXC can have the following configuration: 338 * 339 * EX DEX IXE 340 * 0 1 x - synchronous exception 341 * 1 x 0 - asynchronous exception 342 * 1 x 1 - sychronous on VFP subarch 1 and asynchronous on later 343 * 0 0 1 - synchronous on VFP9 (non-standard subarch 1 344 * implementation), undefined otherwise 345 * 346 * Clear various bits and enable access to the VFP so we can 347 * handle the bounce. 348 */ 349 fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK)); 350 351 fpsid = fmrx(FPSID); 352 orig_fpscr = fpscr = fmrx(FPSCR); 353 354 /* 355 * Check for the special VFP subarch 1 and FPSCR.IXE bit case 356 */ 357 if ((fpsid & FPSID_ARCH_MASK) == (1 << FPSID_ARCH_BIT) 358 && (fpscr & FPSCR_IXE)) { 359 /* 360 * Synchronous exception, emulate the trigger instruction 361 */ 362 goto emulate; 363 } 364 365 if (fpexc & FPEXC_EX) { 366 #ifndef CONFIG_CPU_FEROCEON 367 /* 368 * Asynchronous exception. The instruction is read from FPINST 369 * and the interrupted instruction has to be restarted. 370 */ 371 trigger = fmrx(FPINST); 372 regs->ARM_pc -= 4; 373 #endif 374 } else if (!(fpexc & FPEXC_DEX)) { 375 /* 376 * Illegal combination of bits. It can be caused by an 377 * unallocated VFP instruction but with FPSCR.IXE set and not 378 * on VFP subarch 1. 379 */ 380 vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs); 381 goto exit; 382 } 383 384 /* 385 * Modify fpscr to indicate the number of iterations remaining. 386 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates 387 * whether FPEXC.VECITR or FPSCR.LEN is used. 388 */ 389 if (fpexc & (FPEXC_EX | FPEXC_VV)) { 390 u32 len; 391 392 len = fpexc + (1 << FPEXC_LENGTH_BIT); 393 394 fpscr &= ~FPSCR_LENGTH_MASK; 395 fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT); 396 } 397 398 /* 399 * Handle the first FP instruction. We used to take note of the 400 * FPEXC bounce reason, but this appears to be unreliable. 401 * Emulate the bounced instruction instead. 402 */ 403 exceptions = vfp_emulate_instruction(trigger, fpscr, regs); 404 if (exceptions) 405 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 406 407 /* 408 * If there isn't a second FP instruction, exit now. Note that 409 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1. 410 */ 411 if (fpexc ^ (FPEXC_EX | FPEXC_FP2V)) 412 goto exit; 413 414 /* 415 * The barrier() here prevents fpinst2 being read 416 * before the condition above. 417 */ 418 barrier(); 419 trigger = fmrx(FPINST2); 420 421 emulate: 422 exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs); 423 if (exceptions) 424 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 425 exit: 426 preempt_enable(); 427 } 428 429 static void vfp_enable(void *unused) 430 { 431 u32 access = get_copro_access(); 432 433 /* 434 * Enable full access to VFP (cp10 and cp11) 435 */ 436 set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11)); 437 } 438 439 #ifdef CONFIG_PM 440 #include <linux/syscore_ops.h> 441 442 static int vfp_pm_suspend(void) 443 { 444 struct thread_info *ti = current_thread_info(); 445 u32 fpexc = fmrx(FPEXC); 446 447 /* if vfp is on, then save state for resumption */ 448 if (fpexc & FPEXC_EN) { 449 printk(KERN_DEBUG "%s: saving vfp state\n", __func__); 450 vfp_save_state(&ti->vfpstate, fpexc); 451 452 /* disable, just in case */ 453 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 454 } 455 456 /* clear any information we had about last context state */ 457 memset(vfp_current_hw_state, 0, sizeof(vfp_current_hw_state)); 458 459 return 0; 460 } 461 462 static void vfp_pm_resume(void) 463 { 464 /* ensure we have access to the vfp */ 465 vfp_enable(NULL); 466 467 /* and disable it to ensure the next usage restores the state */ 468 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 469 } 470 471 static struct syscore_ops vfp_pm_syscore_ops = { 472 .suspend = vfp_pm_suspend, 473 .resume = vfp_pm_resume, 474 }; 475 476 static void vfp_pm_init(void) 477 { 478 register_syscore_ops(&vfp_pm_syscore_ops); 479 } 480 481 #else 482 static inline void vfp_pm_init(void) { } 483 #endif /* CONFIG_PM */ 484 485 /* 486 * Ensure that the VFP state stored in 'thread->vfpstate' is up to date 487 * with the hardware state. 488 */ 489 void vfp_sync_hwstate(struct thread_info *thread) 490 { 491 unsigned int cpu = get_cpu(); 492 493 if (vfp_state_in_hw(cpu, thread)) { 494 u32 fpexc = fmrx(FPEXC); 495 496 /* 497 * Save the last VFP state on this CPU. 498 */ 499 fmxr(FPEXC, fpexc | FPEXC_EN); 500 vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN); 501 fmxr(FPEXC, fpexc); 502 } 503 504 put_cpu(); 505 } 506 507 /* Ensure that the thread reloads the hardware VFP state on the next use. */ 508 void vfp_flush_hwstate(struct thread_info *thread) 509 { 510 unsigned int cpu = get_cpu(); 511 512 vfp_force_reload(cpu, thread); 513 514 put_cpu(); 515 } 516 517 /* 518 * VFP hardware can lose all context when a CPU goes offline. 519 * As we will be running in SMP mode with CPU hotplug, we will save the 520 * hardware state at every thread switch. We clear our held state when 521 * a CPU has been killed, indicating that the VFP hardware doesn't contain 522 * a threads VFP state. When a CPU starts up, we re-enable access to the 523 * VFP hardware. 524 * 525 * Both CPU_DYING and CPU_STARTING are called on the CPU which 526 * is being offlined/onlined. 527 */ 528 static int vfp_hotplug(struct notifier_block *b, unsigned long action, 529 void *hcpu) 530 { 531 if (action == CPU_DYING || action == CPU_DYING_FROZEN) { 532 vfp_force_reload((long)hcpu, current_thread_info()); 533 } else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN) 534 vfp_enable(NULL); 535 return NOTIFY_OK; 536 } 537 538 /* 539 * VFP support code initialisation. 540 */ 541 static int __init vfp_init(void) 542 { 543 unsigned int vfpsid; 544 unsigned int cpu_arch = cpu_architecture(); 545 546 if (cpu_arch >= CPU_ARCH_ARMv6) 547 vfp_enable(NULL); 548 549 /* 550 * First check that there is a VFP that we can use. 551 * The handler is already setup to just log calls, so 552 * we just need to read the VFPSID register. 553 */ 554 vfp_vector = vfp_testing_entry; 555 barrier(); 556 vfpsid = fmrx(FPSID); 557 barrier(); 558 vfp_vector = vfp_null_entry; 559 560 printk(KERN_INFO "VFP support v0.3: "); 561 if (VFP_arch) 562 printk("not present\n"); 563 else if (vfpsid & FPSID_NODOUBLE) { 564 printk("no double precision support\n"); 565 } else { 566 hotcpu_notifier(vfp_hotplug, 0); 567 568 smp_call_function(vfp_enable, NULL, 1); 569 570 VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; /* Extract the architecture version */ 571 printk("implementor %02x architecture %d part %02x variant %x rev %x\n", 572 (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT, 573 (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT, 574 (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT, 575 (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT, 576 (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT); 577 578 vfp_vector = vfp_support_entry; 579 580 thread_register_notifier(&vfp_notifier_block); 581 vfp_pm_init(); 582 583 /* 584 * We detected VFP, and the support code is 585 * in place; report VFP support to userspace. 586 */ 587 elf_hwcap |= HWCAP_VFP; 588 #ifdef CONFIG_VFPv3 589 if (VFP_arch >= 2) { 590 elf_hwcap |= HWCAP_VFPv3; 591 592 /* 593 * Check for VFPv3 D16. CPUs in this configuration 594 * only have 16 x 64bit registers. 595 */ 596 if (((fmrx(MVFR0) & MVFR0_A_SIMD_MASK)) == 1) 597 elf_hwcap |= HWCAP_VFPv3D16; 598 } 599 #endif 600 /* 601 * Check for the presence of the Advanced SIMD 602 * load/store instructions, integer and single 603 * precision floating point operations. Only check 604 * for NEON if the hardware has the MVFR registers. 605 */ 606 if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) { 607 #ifdef CONFIG_NEON 608 if ((fmrx(MVFR1) & 0x000fff00) == 0x00011100) 609 elf_hwcap |= HWCAP_NEON; 610 #endif 611 if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000) 612 elf_hwcap |= HWCAP_VFPv4; 613 } 614 } 615 return 0; 616 } 617 618 late_initcall(vfp_init); 619