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/types.h> 12 #include <linux/cpu.h> 13 #include <linux/cpu_pm.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 #include <linux/uaccess.h> 21 #include <linux/user.h> 22 23 #include <asm/cp15.h> 24 #include <asm/cputype.h> 25 #include <asm/system_info.h> 26 #include <asm/thread_notify.h> 27 #include <asm/vfp.h> 28 29 #include "vfpinstr.h" 30 #include "vfp.h" 31 32 /* 33 * Our undef handlers (in entry.S) 34 */ 35 void vfp_testing_entry(void); 36 void vfp_support_entry(void); 37 void vfp_null_entry(void); 38 39 void (*vfp_vector)(void) = vfp_null_entry; 40 41 /* 42 * Dual-use variable. 43 * Used in startup: set to non-zero if VFP checks fail 44 * After startup, holds VFP architecture 45 */ 46 unsigned int VFP_arch; 47 48 /* 49 * The pointer to the vfpstate structure of the thread which currently 50 * owns the context held in the VFP hardware, or NULL if the hardware 51 * context is invalid. 52 * 53 * For UP, this is sufficient to tell which thread owns the VFP context. 54 * However, for SMP, we also need to check the CPU number stored in the 55 * saved state too to catch migrations. 56 */ 57 union vfp_state *vfp_current_hw_state[NR_CPUS]; 58 59 /* 60 * Is 'thread's most up to date state stored in this CPUs hardware? 61 * Must be called from non-preemptible context. 62 */ 63 static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread) 64 { 65 #ifdef CONFIG_SMP 66 if (thread->vfpstate.hard.cpu != cpu) 67 return false; 68 #endif 69 return vfp_current_hw_state[cpu] == &thread->vfpstate; 70 } 71 72 /* 73 * Force a reload of the VFP context from the thread structure. We do 74 * this by ensuring that access to the VFP hardware is disabled, and 75 * clear vfp_current_hw_state. Must be called from non-preemptible context. 76 */ 77 static void vfp_force_reload(unsigned int cpu, struct thread_info *thread) 78 { 79 if (vfp_state_in_hw(cpu, thread)) { 80 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 81 vfp_current_hw_state[cpu] = NULL; 82 } 83 #ifdef CONFIG_SMP 84 thread->vfpstate.hard.cpu = NR_CPUS; 85 #endif 86 } 87 88 /* 89 * Per-thread VFP initialization. 90 */ 91 static void vfp_thread_flush(struct thread_info *thread) 92 { 93 union vfp_state *vfp = &thread->vfpstate; 94 unsigned int cpu; 95 96 /* 97 * Disable VFP to ensure we initialize it first. We must ensure 98 * that the modification of vfp_current_hw_state[] and hardware 99 * disable are done for the same CPU and without preemption. 100 * 101 * Do this first to ensure that preemption won't overwrite our 102 * state saving should access to the VFP be enabled at this point. 103 */ 104 cpu = get_cpu(); 105 if (vfp_current_hw_state[cpu] == vfp) 106 vfp_current_hw_state[cpu] = NULL; 107 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 108 put_cpu(); 109 110 memset(vfp, 0, sizeof(union vfp_state)); 111 112 vfp->hard.fpexc = FPEXC_EN; 113 vfp->hard.fpscr = FPSCR_ROUND_NEAREST; 114 #ifdef CONFIG_SMP 115 vfp->hard.cpu = NR_CPUS; 116 #endif 117 } 118 119 static void vfp_thread_exit(struct thread_info *thread) 120 { 121 /* release case: Per-thread VFP cleanup. */ 122 union vfp_state *vfp = &thread->vfpstate; 123 unsigned int cpu = get_cpu(); 124 125 if (vfp_current_hw_state[cpu] == vfp) 126 vfp_current_hw_state[cpu] = NULL; 127 put_cpu(); 128 } 129 130 static void vfp_thread_copy(struct thread_info *thread) 131 { 132 struct thread_info *parent = current_thread_info(); 133 134 vfp_sync_hwstate(parent); 135 thread->vfpstate = parent->vfpstate; 136 #ifdef CONFIG_SMP 137 thread->vfpstate.hard.cpu = NR_CPUS; 138 #endif 139 } 140 141 /* 142 * When this function is called with the following 'cmd's, the following 143 * is true while this function is being run: 144 * THREAD_NOFTIFY_SWTICH: 145 * - the previously running thread will not be scheduled onto another CPU. 146 * - the next thread to be run (v) will not be running on another CPU. 147 * - thread->cpu is the local CPU number 148 * - not preemptible as we're called in the middle of a thread switch 149 * THREAD_NOTIFY_FLUSH: 150 * - the thread (v) will be running on the local CPU, so 151 * v === current_thread_info() 152 * - thread->cpu is the local CPU number at the time it is accessed, 153 * but may change at any time. 154 * - we could be preempted if tree preempt rcu is enabled, so 155 * it is unsafe to use thread->cpu. 156 * THREAD_NOTIFY_EXIT 157 * - the thread (v) will be running on the local CPU, so 158 * v === current_thread_info() 159 * - thread->cpu is the local CPU number at the time it is accessed, 160 * but may change at any time. 161 * - we could be preempted if tree preempt rcu is enabled, so 162 * it is unsafe to use thread->cpu. 163 */ 164 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v) 165 { 166 struct thread_info *thread = v; 167 u32 fpexc; 168 #ifdef CONFIG_SMP 169 unsigned int cpu; 170 #endif 171 172 switch (cmd) { 173 case THREAD_NOTIFY_SWITCH: 174 fpexc = fmrx(FPEXC); 175 176 #ifdef CONFIG_SMP 177 cpu = thread->cpu; 178 179 /* 180 * On SMP, if VFP is enabled, save the old state in 181 * case the thread migrates to a different CPU. The 182 * restoring is done lazily. 183 */ 184 if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) 185 vfp_save_state(vfp_current_hw_state[cpu], fpexc); 186 #endif 187 188 /* 189 * Always disable VFP so we can lazily save/restore the 190 * old state. 191 */ 192 fmxr(FPEXC, fpexc & ~FPEXC_EN); 193 break; 194 195 case THREAD_NOTIFY_FLUSH: 196 vfp_thread_flush(thread); 197 break; 198 199 case THREAD_NOTIFY_EXIT: 200 vfp_thread_exit(thread); 201 break; 202 203 case THREAD_NOTIFY_COPY: 204 vfp_thread_copy(thread); 205 break; 206 } 207 208 return NOTIFY_DONE; 209 } 210 211 static struct notifier_block vfp_notifier_block = { 212 .notifier_call = vfp_notifier, 213 }; 214 215 /* 216 * Raise a SIGFPE for the current process. 217 * sicode describes the signal being raised. 218 */ 219 static void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs) 220 { 221 siginfo_t info; 222 223 memset(&info, 0, sizeof(info)); 224 225 info.si_signo = SIGFPE; 226 info.si_code = sicode; 227 info.si_addr = (void __user *)(instruction_pointer(regs) - 4); 228 229 /* 230 * This is the same as NWFPE, because it's not clear what 231 * this is used for 232 */ 233 current->thread.error_code = 0; 234 current->thread.trap_no = 6; 235 236 send_sig_info(SIGFPE, &info, current); 237 } 238 239 static void vfp_panic(char *reason, u32 inst) 240 { 241 int i; 242 243 printk(KERN_ERR "VFP: Error: %s\n", reason); 244 printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n", 245 fmrx(FPEXC), fmrx(FPSCR), inst); 246 for (i = 0; i < 32; i += 2) 247 printk(KERN_ERR "VFP: s%2u: 0x%08x s%2u: 0x%08x\n", 248 i, vfp_get_float(i), i+1, vfp_get_float(i+1)); 249 } 250 251 /* 252 * Process bitmask of exception conditions. 253 */ 254 static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs) 255 { 256 int si_code = 0; 257 258 pr_debug("VFP: raising exceptions %08x\n", exceptions); 259 260 if (exceptions == VFP_EXCEPTION_ERROR) { 261 vfp_panic("unhandled bounce", inst); 262 vfp_raise_sigfpe(0, regs); 263 return; 264 } 265 266 /* 267 * If any of the status flags are set, update the FPSCR. 268 * Comparison instructions always return at least one of 269 * these flags set. 270 */ 271 if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V)) 272 fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V); 273 274 fpscr |= exceptions; 275 276 fmxr(FPSCR, fpscr); 277 278 #define RAISE(stat,en,sig) \ 279 if (exceptions & stat && fpscr & en) \ 280 si_code = sig; 281 282 /* 283 * These are arranged in priority order, least to highest. 284 */ 285 RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV); 286 RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES); 287 RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND); 288 RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF); 289 RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV); 290 291 if (si_code) 292 vfp_raise_sigfpe(si_code, regs); 293 } 294 295 /* 296 * Emulate a VFP instruction. 297 */ 298 static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs) 299 { 300 u32 exceptions = VFP_EXCEPTION_ERROR; 301 302 pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr); 303 304 if (INST_CPRTDO(inst)) { 305 if (!INST_CPRT(inst)) { 306 /* 307 * CPDO 308 */ 309 if (vfp_single(inst)) { 310 exceptions = vfp_single_cpdo(inst, fpscr); 311 } else { 312 exceptions = vfp_double_cpdo(inst, fpscr); 313 } 314 } else { 315 /* 316 * A CPRT instruction can not appear in FPINST2, nor 317 * can it cause an exception. Therefore, we do not 318 * have to emulate it. 319 */ 320 } 321 } else { 322 /* 323 * A CPDT instruction can not appear in FPINST2, nor can 324 * it cause an exception. Therefore, we do not have to 325 * emulate it. 326 */ 327 } 328 return exceptions & ~VFP_NAN_FLAG; 329 } 330 331 /* 332 * Package up a bounce condition. 333 */ 334 void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) 335 { 336 u32 fpscr, orig_fpscr, fpsid, exceptions; 337 338 pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc); 339 340 /* 341 * At this point, FPEXC can have the following configuration: 342 * 343 * EX DEX IXE 344 * 0 1 x - synchronous exception 345 * 1 x 0 - asynchronous exception 346 * 1 x 1 - sychronous on VFP subarch 1 and asynchronous on later 347 * 0 0 1 - synchronous on VFP9 (non-standard subarch 1 348 * implementation), undefined otherwise 349 * 350 * Clear various bits and enable access to the VFP so we can 351 * handle the bounce. 352 */ 353 fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK)); 354 355 fpsid = fmrx(FPSID); 356 orig_fpscr = fpscr = fmrx(FPSCR); 357 358 /* 359 * Check for the special VFP subarch 1 and FPSCR.IXE bit case 360 */ 361 if ((fpsid & FPSID_ARCH_MASK) == (1 << FPSID_ARCH_BIT) 362 && (fpscr & FPSCR_IXE)) { 363 /* 364 * Synchronous exception, emulate the trigger instruction 365 */ 366 goto emulate; 367 } 368 369 if (fpexc & FPEXC_EX) { 370 #ifndef CONFIG_CPU_FEROCEON 371 /* 372 * Asynchronous exception. The instruction is read from FPINST 373 * and the interrupted instruction has to be restarted. 374 */ 375 trigger = fmrx(FPINST); 376 regs->ARM_pc -= 4; 377 #endif 378 } else if (!(fpexc & FPEXC_DEX)) { 379 /* 380 * Illegal combination of bits. It can be caused by an 381 * unallocated VFP instruction but with FPSCR.IXE set and not 382 * on VFP subarch 1. 383 */ 384 vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs); 385 goto exit; 386 } 387 388 /* 389 * Modify fpscr to indicate the number of iterations remaining. 390 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates 391 * whether FPEXC.VECITR or FPSCR.LEN is used. 392 */ 393 if (fpexc & (FPEXC_EX | FPEXC_VV)) { 394 u32 len; 395 396 len = fpexc + (1 << FPEXC_LENGTH_BIT); 397 398 fpscr &= ~FPSCR_LENGTH_MASK; 399 fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT); 400 } 401 402 /* 403 * Handle the first FP instruction. We used to take note of the 404 * FPEXC bounce reason, but this appears to be unreliable. 405 * Emulate the bounced instruction instead. 406 */ 407 exceptions = vfp_emulate_instruction(trigger, fpscr, regs); 408 if (exceptions) 409 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 410 411 /* 412 * If there isn't a second FP instruction, exit now. Note that 413 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1. 414 */ 415 if (fpexc ^ (FPEXC_EX | FPEXC_FP2V)) 416 goto exit; 417 418 /* 419 * The barrier() here prevents fpinst2 being read 420 * before the condition above. 421 */ 422 barrier(); 423 trigger = fmrx(FPINST2); 424 425 emulate: 426 exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs); 427 if (exceptions) 428 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 429 exit: 430 preempt_enable(); 431 } 432 433 static void vfp_enable(void *unused) 434 { 435 u32 access = get_copro_access(); 436 437 /* 438 * Enable full access to VFP (cp10 and cp11) 439 */ 440 set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11)); 441 } 442 443 #ifdef CONFIG_CPU_PM 444 static int vfp_pm_suspend(void) 445 { 446 struct thread_info *ti = current_thread_info(); 447 u32 fpexc = fmrx(FPEXC); 448 449 /* if vfp is on, then save state for resumption */ 450 if (fpexc & FPEXC_EN) { 451 printk(KERN_DEBUG "%s: saving vfp state\n", __func__); 452 vfp_save_state(&ti->vfpstate, fpexc); 453 454 /* disable, just in case */ 455 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 456 } 457 458 /* clear any information we had about last context state */ 459 memset(vfp_current_hw_state, 0, sizeof(vfp_current_hw_state)); 460 461 return 0; 462 } 463 464 static void vfp_pm_resume(void) 465 { 466 /* ensure we have access to the vfp */ 467 vfp_enable(NULL); 468 469 /* and disable it to ensure the next usage restores the state */ 470 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 471 } 472 473 static int vfp_cpu_pm_notifier(struct notifier_block *self, unsigned long cmd, 474 void *v) 475 { 476 switch (cmd) { 477 case CPU_PM_ENTER: 478 vfp_pm_suspend(); 479 break; 480 case CPU_PM_ENTER_FAILED: 481 case CPU_PM_EXIT: 482 vfp_pm_resume(); 483 break; 484 } 485 return NOTIFY_OK; 486 } 487 488 static struct notifier_block vfp_cpu_pm_notifier_block = { 489 .notifier_call = vfp_cpu_pm_notifier, 490 }; 491 492 static void vfp_pm_init(void) 493 { 494 cpu_pm_register_notifier(&vfp_cpu_pm_notifier_block); 495 } 496 497 #else 498 static inline void vfp_pm_init(void) { } 499 #endif /* CONFIG_CPU_PM */ 500 501 /* 502 * Ensure that the VFP state stored in 'thread->vfpstate' is up to date 503 * with the hardware state. 504 */ 505 void vfp_sync_hwstate(struct thread_info *thread) 506 { 507 unsigned int cpu = get_cpu(); 508 509 if (vfp_state_in_hw(cpu, thread)) { 510 u32 fpexc = fmrx(FPEXC); 511 512 /* 513 * Save the last VFP state on this CPU. 514 */ 515 fmxr(FPEXC, fpexc | FPEXC_EN); 516 vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN); 517 fmxr(FPEXC, fpexc); 518 } 519 520 put_cpu(); 521 } 522 523 /* Ensure that the thread reloads the hardware VFP state on the next use. */ 524 void vfp_flush_hwstate(struct thread_info *thread) 525 { 526 unsigned int cpu = get_cpu(); 527 528 vfp_force_reload(cpu, thread); 529 530 put_cpu(); 531 } 532 533 /* 534 * Save the current VFP state into the provided structures and prepare 535 * for entry into a new function (signal handler). 536 */ 537 int vfp_preserve_user_clear_hwstate(struct user_vfp __user *ufp, 538 struct user_vfp_exc __user *ufp_exc) 539 { 540 struct thread_info *thread = current_thread_info(); 541 struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; 542 int err = 0; 543 544 /* Ensure that the saved hwstate is up-to-date. */ 545 vfp_sync_hwstate(thread); 546 547 /* 548 * Copy the floating point registers. There can be unused 549 * registers see asm/hwcap.h for details. 550 */ 551 err |= __copy_to_user(&ufp->fpregs, &hwstate->fpregs, 552 sizeof(hwstate->fpregs)); 553 /* 554 * Copy the status and control register. 555 */ 556 __put_user_error(hwstate->fpscr, &ufp->fpscr, err); 557 558 /* 559 * Copy the exception registers. 560 */ 561 __put_user_error(hwstate->fpexc, &ufp_exc->fpexc, err); 562 __put_user_error(hwstate->fpinst, &ufp_exc->fpinst, err); 563 __put_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err); 564 565 if (err) 566 return -EFAULT; 567 568 /* Ensure that VFP is disabled. */ 569 vfp_flush_hwstate(thread); 570 571 /* 572 * As per the PCS, clear the length and stride bits for function 573 * entry. 574 */ 575 hwstate->fpscr &= ~(FPSCR_LENGTH_MASK | FPSCR_STRIDE_MASK); 576 577 /* 578 * Disable VFP in the hwstate so that we can detect if it gets 579 * used. 580 */ 581 hwstate->fpexc &= ~FPEXC_EN; 582 return 0; 583 } 584 585 /* Sanitise and restore the current VFP state from the provided structures. */ 586 int vfp_restore_user_hwstate(struct user_vfp __user *ufp, 587 struct user_vfp_exc __user *ufp_exc) 588 { 589 struct thread_info *thread = current_thread_info(); 590 struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; 591 unsigned long fpexc; 592 int err = 0; 593 594 /* 595 * If VFP has been used, then disable it to avoid corrupting 596 * the new thread state. 597 */ 598 if (hwstate->fpexc & FPEXC_EN) 599 vfp_flush_hwstate(thread); 600 601 /* 602 * Copy the floating point registers. There can be unused 603 * registers see asm/hwcap.h for details. 604 */ 605 err |= __copy_from_user(&hwstate->fpregs, &ufp->fpregs, 606 sizeof(hwstate->fpregs)); 607 /* 608 * Copy the status and control register. 609 */ 610 __get_user_error(hwstate->fpscr, &ufp->fpscr, err); 611 612 /* 613 * Sanitise and restore the exception registers. 614 */ 615 __get_user_error(fpexc, &ufp_exc->fpexc, err); 616 617 /* Ensure the VFP is enabled. */ 618 fpexc |= FPEXC_EN; 619 620 /* Ensure FPINST2 is invalid and the exception flag is cleared. */ 621 fpexc &= ~(FPEXC_EX | FPEXC_FP2V); 622 hwstate->fpexc = fpexc; 623 624 __get_user_error(hwstate->fpinst, &ufp_exc->fpinst, err); 625 __get_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err); 626 627 return err ? -EFAULT : 0; 628 } 629 630 /* 631 * VFP hardware can lose all context when a CPU goes offline. 632 * As we will be running in SMP mode with CPU hotplug, we will save the 633 * hardware state at every thread switch. We clear our held state when 634 * a CPU has been killed, indicating that the VFP hardware doesn't contain 635 * a threads VFP state. When a CPU starts up, we re-enable access to the 636 * VFP hardware. 637 * 638 * Both CPU_DYING and CPU_STARTING are called on the CPU which 639 * is being offlined/onlined. 640 */ 641 static int vfp_hotplug(struct notifier_block *b, unsigned long action, 642 void *hcpu) 643 { 644 if (action == CPU_DYING || action == CPU_DYING_FROZEN) { 645 vfp_force_reload((long)hcpu, current_thread_info()); 646 } else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN) 647 vfp_enable(NULL); 648 return NOTIFY_OK; 649 } 650 651 /* 652 * VFP support code initialisation. 653 */ 654 static int __init vfp_init(void) 655 { 656 unsigned int vfpsid; 657 unsigned int cpu_arch = cpu_architecture(); 658 659 if (cpu_arch >= CPU_ARCH_ARMv6) 660 vfp_enable(NULL); 661 662 /* 663 * First check that there is a VFP that we can use. 664 * The handler is already setup to just log calls, so 665 * we just need to read the VFPSID register. 666 */ 667 vfp_vector = vfp_testing_entry; 668 barrier(); 669 vfpsid = fmrx(FPSID); 670 barrier(); 671 vfp_vector = vfp_null_entry; 672 673 printk(KERN_INFO "VFP support v0.3: "); 674 if (VFP_arch) 675 printk("not present\n"); 676 else if (vfpsid & FPSID_NODOUBLE) { 677 printk("no double precision support\n"); 678 } else { 679 hotcpu_notifier(vfp_hotplug, 0); 680 681 smp_call_function(vfp_enable, NULL, 1); 682 683 VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; /* Extract the architecture version */ 684 printk("implementor %02x architecture %d part %02x variant %x rev %x\n", 685 (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT, 686 (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT, 687 (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT, 688 (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT, 689 (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT); 690 691 vfp_vector = vfp_support_entry; 692 693 thread_register_notifier(&vfp_notifier_block); 694 vfp_pm_init(); 695 696 /* 697 * We detected VFP, and the support code is 698 * in place; report VFP support to userspace. 699 */ 700 elf_hwcap |= HWCAP_VFP; 701 #ifdef CONFIG_VFPv3 702 if (VFP_arch >= 2) { 703 elf_hwcap |= HWCAP_VFPv3; 704 705 /* 706 * Check for VFPv3 D16. CPUs in this configuration 707 * only have 16 x 64bit registers. 708 */ 709 if (((fmrx(MVFR0) & MVFR0_A_SIMD_MASK)) == 1) 710 elf_hwcap |= HWCAP_VFPv3D16; 711 } 712 #endif 713 /* 714 * Check for the presence of the Advanced SIMD 715 * load/store instructions, integer and single 716 * precision floating point operations. Only check 717 * for NEON if the hardware has the MVFR registers. 718 */ 719 if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) { 720 #ifdef CONFIG_NEON 721 if ((fmrx(MVFR1) & 0x000fff00) == 0x00011100) 722 elf_hwcap |= HWCAP_NEON; 723 #endif 724 if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000) 725 elf_hwcap |= HWCAP_VFPv4; 726 } 727 } 728 return 0; 729 } 730 731 late_initcall(vfp_init); 732