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/hardirq.h> 15 #include <linux/kernel.h> 16 #include <linux/notifier.h> 17 #include <linux/signal.h> 18 #include <linux/sched.h> 19 #include <linux/smp.h> 20 #include <linux/init.h> 21 #include <linux/uaccess.h> 22 #include <linux/user.h> 23 #include <linux/export.h> 24 25 #include <asm/cp15.h> 26 #include <asm/cputype.h> 27 #include <asm/system_info.h> 28 #include <asm/thread_notify.h> 29 #include <asm/vfp.h> 30 31 #include "vfpinstr.h" 32 #include "vfp.h" 33 34 /* 35 * Our undef handlers (in entry.S) 36 */ 37 void vfp_testing_entry(void); 38 void vfp_support_entry(void); 39 void vfp_null_entry(void); 40 41 void (*vfp_vector)(void) = vfp_null_entry; 42 43 /* 44 * Dual-use variable. 45 * Used in startup: set to non-zero if VFP checks fail 46 * After startup, holds VFP architecture 47 */ 48 unsigned int VFP_arch; 49 50 /* 51 * The pointer to the vfpstate structure of the thread which currently 52 * owns the context held in the VFP hardware, or NULL if the hardware 53 * context is invalid. 54 * 55 * For UP, this is sufficient to tell which thread owns the VFP context. 56 * However, for SMP, we also need to check the CPU number stored in the 57 * saved state too to catch migrations. 58 */ 59 union vfp_state *vfp_current_hw_state[NR_CPUS]; 60 61 /* 62 * Is 'thread's most up to date state stored in this CPUs hardware? 63 * Must be called from non-preemptible context. 64 */ 65 static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread) 66 { 67 #ifdef CONFIG_SMP 68 if (thread->vfpstate.hard.cpu != cpu) 69 return false; 70 #endif 71 return vfp_current_hw_state[cpu] == &thread->vfpstate; 72 } 73 74 /* 75 * Force a reload of the VFP context from the thread structure. We do 76 * this by ensuring that access to the VFP hardware is disabled, and 77 * clear vfp_current_hw_state. Must be called from non-preemptible context. 78 */ 79 static void vfp_force_reload(unsigned int cpu, struct thread_info *thread) 80 { 81 if (vfp_state_in_hw(cpu, thread)) { 82 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 83 vfp_current_hw_state[cpu] = NULL; 84 } 85 #ifdef CONFIG_SMP 86 thread->vfpstate.hard.cpu = NR_CPUS; 87 #endif 88 } 89 90 /* 91 * Per-thread VFP initialization. 92 */ 93 static void vfp_thread_flush(struct thread_info *thread) 94 { 95 union vfp_state *vfp = &thread->vfpstate; 96 unsigned int cpu; 97 98 /* 99 * Disable VFP to ensure we initialize it first. We must ensure 100 * that the modification of vfp_current_hw_state[] and hardware 101 * disable are done for the same CPU and without preemption. 102 * 103 * Do this first to ensure that preemption won't overwrite our 104 * state saving should access to the VFP be enabled at this point. 105 */ 106 cpu = get_cpu(); 107 if (vfp_current_hw_state[cpu] == vfp) 108 vfp_current_hw_state[cpu] = NULL; 109 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 110 put_cpu(); 111 112 memset(vfp, 0, sizeof(union vfp_state)); 113 114 vfp->hard.fpexc = FPEXC_EN; 115 vfp->hard.fpscr = FPSCR_ROUND_NEAREST; 116 #ifdef CONFIG_SMP 117 vfp->hard.cpu = NR_CPUS; 118 #endif 119 } 120 121 static void vfp_thread_exit(struct thread_info *thread) 122 { 123 /* release case: Per-thread VFP cleanup. */ 124 union vfp_state *vfp = &thread->vfpstate; 125 unsigned int cpu = get_cpu(); 126 127 if (vfp_current_hw_state[cpu] == vfp) 128 vfp_current_hw_state[cpu] = NULL; 129 put_cpu(); 130 } 131 132 static void vfp_thread_copy(struct thread_info *thread) 133 { 134 struct thread_info *parent = current_thread_info(); 135 136 vfp_sync_hwstate(parent); 137 thread->vfpstate = parent->vfpstate; 138 #ifdef CONFIG_SMP 139 thread->vfpstate.hard.cpu = NR_CPUS; 140 #endif 141 } 142 143 /* 144 * When this function is called with the following 'cmd's, the following 145 * is true while this function is being run: 146 * THREAD_NOFTIFY_SWTICH: 147 * - the previously running thread will not be scheduled onto another CPU. 148 * - the next thread to be run (v) will not be running on another CPU. 149 * - thread->cpu is the local CPU number 150 * - not preemptible as we're called in the middle of a thread switch 151 * THREAD_NOTIFY_FLUSH: 152 * - the thread (v) will be running on the local CPU, so 153 * v === current_thread_info() 154 * - thread->cpu is the local CPU number at the time it is accessed, 155 * but may change at any time. 156 * - we could be preempted if tree preempt rcu is enabled, so 157 * it is unsafe to use thread->cpu. 158 * THREAD_NOTIFY_EXIT 159 * - the thread (v) will be running on the local CPU, so 160 * v === current_thread_info() 161 * - thread->cpu is the local CPU number at the time it is accessed, 162 * but may change at any time. 163 * - we could be preempted if tree preempt rcu is enabled, so 164 * it is unsafe to use thread->cpu. 165 */ 166 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v) 167 { 168 struct thread_info *thread = v; 169 u32 fpexc; 170 #ifdef CONFIG_SMP 171 unsigned int cpu; 172 #endif 173 174 switch (cmd) { 175 case THREAD_NOTIFY_SWITCH: 176 fpexc = fmrx(FPEXC); 177 178 #ifdef CONFIG_SMP 179 cpu = thread->cpu; 180 181 /* 182 * On SMP, if VFP is enabled, save the old state in 183 * case the thread migrates to a different CPU. The 184 * restoring is done lazily. 185 */ 186 if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) 187 vfp_save_state(vfp_current_hw_state[cpu], fpexc); 188 #endif 189 190 /* 191 * Always disable VFP so we can lazily save/restore the 192 * old state. 193 */ 194 fmxr(FPEXC, fpexc & ~FPEXC_EN); 195 break; 196 197 case THREAD_NOTIFY_FLUSH: 198 vfp_thread_flush(thread); 199 break; 200 201 case THREAD_NOTIFY_EXIT: 202 vfp_thread_exit(thread); 203 break; 204 205 case THREAD_NOTIFY_COPY: 206 vfp_thread_copy(thread); 207 break; 208 } 209 210 return NOTIFY_DONE; 211 } 212 213 static struct notifier_block vfp_notifier_block = { 214 .notifier_call = vfp_notifier, 215 }; 216 217 /* 218 * Raise a SIGFPE for the current process. 219 * sicode describes the signal being raised. 220 */ 221 static void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs) 222 { 223 siginfo_t info; 224 225 memset(&info, 0, sizeof(info)); 226 227 info.si_signo = SIGFPE; 228 info.si_code = sicode; 229 info.si_addr = (void __user *)(instruction_pointer(regs) - 4); 230 231 /* 232 * This is the same as NWFPE, because it's not clear what 233 * this is used for 234 */ 235 current->thread.error_code = 0; 236 current->thread.trap_no = 6; 237 238 send_sig_info(SIGFPE, &info, current); 239 } 240 241 static void vfp_panic(char *reason, u32 inst) 242 { 243 int i; 244 245 pr_err("VFP: Error: %s\n", reason); 246 pr_err("VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n", 247 fmrx(FPEXC), fmrx(FPSCR), inst); 248 for (i = 0; i < 32; i += 2) 249 pr_err("VFP: s%2u: 0x%08x s%2u: 0x%08x\n", 250 i, vfp_get_float(i), i+1, vfp_get_float(i+1)); 251 } 252 253 /* 254 * Process bitmask of exception conditions. 255 */ 256 static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs) 257 { 258 int si_code = 0; 259 260 pr_debug("VFP: raising exceptions %08x\n", exceptions); 261 262 if (exceptions == VFP_EXCEPTION_ERROR) { 263 vfp_panic("unhandled bounce", inst); 264 vfp_raise_sigfpe(0, regs); 265 return; 266 } 267 268 /* 269 * If any of the status flags are set, update the FPSCR. 270 * Comparison instructions always return at least one of 271 * these flags set. 272 */ 273 if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V)) 274 fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V); 275 276 fpscr |= exceptions; 277 278 fmxr(FPSCR, fpscr); 279 280 #define RAISE(stat,en,sig) \ 281 if (exceptions & stat && fpscr & en) \ 282 si_code = sig; 283 284 /* 285 * These are arranged in priority order, least to highest. 286 */ 287 RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV); 288 RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES); 289 RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND); 290 RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF); 291 RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV); 292 293 if (si_code) 294 vfp_raise_sigfpe(si_code, regs); 295 } 296 297 /* 298 * Emulate a VFP instruction. 299 */ 300 static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs) 301 { 302 u32 exceptions = VFP_EXCEPTION_ERROR; 303 304 pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr); 305 306 if (INST_CPRTDO(inst)) { 307 if (!INST_CPRT(inst)) { 308 /* 309 * CPDO 310 */ 311 if (vfp_single(inst)) { 312 exceptions = vfp_single_cpdo(inst, fpscr); 313 } else { 314 exceptions = vfp_double_cpdo(inst, fpscr); 315 } 316 } else { 317 /* 318 * A CPRT instruction can not appear in FPINST2, nor 319 * can it cause an exception. Therefore, we do not 320 * have to emulate it. 321 */ 322 } 323 } else { 324 /* 325 * A CPDT instruction can not appear in FPINST2, nor can 326 * it cause an exception. Therefore, we do not have to 327 * emulate it. 328 */ 329 } 330 return exceptions & ~VFP_NAN_FLAG; 331 } 332 333 /* 334 * Package up a bounce condition. 335 */ 336 void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) 337 { 338 u32 fpscr, orig_fpscr, fpsid, exceptions; 339 340 pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc); 341 342 /* 343 * At this point, FPEXC can have the following configuration: 344 * 345 * EX DEX IXE 346 * 0 1 x - synchronous exception 347 * 1 x 0 - asynchronous exception 348 * 1 x 1 - sychronous on VFP subarch 1 and asynchronous on later 349 * 0 0 1 - synchronous on VFP9 (non-standard subarch 1 350 * implementation), undefined otherwise 351 * 352 * Clear various bits and enable access to the VFP so we can 353 * handle the bounce. 354 */ 355 fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK)); 356 357 fpsid = fmrx(FPSID); 358 orig_fpscr = fpscr = fmrx(FPSCR); 359 360 /* 361 * Check for the special VFP subarch 1 and FPSCR.IXE bit case 362 */ 363 if ((fpsid & FPSID_ARCH_MASK) == (1 << FPSID_ARCH_BIT) 364 && (fpscr & FPSCR_IXE)) { 365 /* 366 * Synchronous exception, emulate the trigger instruction 367 */ 368 goto emulate; 369 } 370 371 if (fpexc & FPEXC_EX) { 372 #ifndef CONFIG_CPU_FEROCEON 373 /* 374 * Asynchronous exception. The instruction is read from FPINST 375 * and the interrupted instruction has to be restarted. 376 */ 377 trigger = fmrx(FPINST); 378 regs->ARM_pc -= 4; 379 #endif 380 } else if (!(fpexc & FPEXC_DEX)) { 381 /* 382 * Illegal combination of bits. It can be caused by an 383 * unallocated VFP instruction but with FPSCR.IXE set and not 384 * on VFP subarch 1. 385 */ 386 vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs); 387 goto exit; 388 } 389 390 /* 391 * Modify fpscr to indicate the number of iterations remaining. 392 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates 393 * whether FPEXC.VECITR or FPSCR.LEN is used. 394 */ 395 if (fpexc & (FPEXC_EX | FPEXC_VV)) { 396 u32 len; 397 398 len = fpexc + (1 << FPEXC_LENGTH_BIT); 399 400 fpscr &= ~FPSCR_LENGTH_MASK; 401 fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT); 402 } 403 404 /* 405 * Handle the first FP instruction. We used to take note of the 406 * FPEXC bounce reason, but this appears to be unreliable. 407 * Emulate the bounced instruction instead. 408 */ 409 exceptions = vfp_emulate_instruction(trigger, fpscr, regs); 410 if (exceptions) 411 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 412 413 /* 414 * If there isn't a second FP instruction, exit now. Note that 415 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1. 416 */ 417 if ((fpexc & (FPEXC_EX | FPEXC_FP2V)) != (FPEXC_EX | FPEXC_FP2V)) 418 goto exit; 419 420 /* 421 * The barrier() here prevents fpinst2 being read 422 * before the condition above. 423 */ 424 barrier(); 425 trigger = fmrx(FPINST2); 426 427 emulate: 428 exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs); 429 if (exceptions) 430 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 431 exit: 432 preempt_enable(); 433 } 434 435 static void vfp_enable(void *unused) 436 { 437 u32 access; 438 439 BUG_ON(preemptible()); 440 access = get_copro_access(); 441 442 /* 443 * Enable full access to VFP (cp10 and cp11) 444 */ 445 set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11)); 446 } 447 448 /* Called by platforms on which we want to disable VFP because it may not be 449 * present on all CPUs within a SMP complex. Needs to be called prior to 450 * vfp_init(). 451 */ 452 void vfp_disable(void) 453 { 454 if (VFP_arch) { 455 pr_debug("%s: should be called prior to vfp_init\n", __func__); 456 return; 457 } 458 VFP_arch = 1; 459 } 460 461 #ifdef CONFIG_CPU_PM 462 static int vfp_pm_suspend(void) 463 { 464 struct thread_info *ti = current_thread_info(); 465 u32 fpexc = fmrx(FPEXC); 466 467 /* if vfp is on, then save state for resumption */ 468 if (fpexc & FPEXC_EN) { 469 pr_debug("%s: saving vfp state\n", __func__); 470 vfp_save_state(&ti->vfpstate, fpexc); 471 472 /* disable, just in case */ 473 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 474 } else if (vfp_current_hw_state[ti->cpu]) { 475 #ifndef CONFIG_SMP 476 fmxr(FPEXC, fpexc | FPEXC_EN); 477 vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc); 478 fmxr(FPEXC, fpexc); 479 #endif 480 } 481 482 /* clear any information we had about last context state */ 483 vfp_current_hw_state[ti->cpu] = NULL; 484 485 return 0; 486 } 487 488 static void vfp_pm_resume(void) 489 { 490 /* ensure we have access to the vfp */ 491 vfp_enable(NULL); 492 493 /* and disable it to ensure the next usage restores the state */ 494 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 495 } 496 497 static int vfp_cpu_pm_notifier(struct notifier_block *self, unsigned long cmd, 498 void *v) 499 { 500 switch (cmd) { 501 case CPU_PM_ENTER: 502 vfp_pm_suspend(); 503 break; 504 case CPU_PM_ENTER_FAILED: 505 case CPU_PM_EXIT: 506 vfp_pm_resume(); 507 break; 508 } 509 return NOTIFY_OK; 510 } 511 512 static struct notifier_block vfp_cpu_pm_notifier_block = { 513 .notifier_call = vfp_cpu_pm_notifier, 514 }; 515 516 static void vfp_pm_init(void) 517 { 518 cpu_pm_register_notifier(&vfp_cpu_pm_notifier_block); 519 } 520 521 #else 522 static inline void vfp_pm_init(void) { } 523 #endif /* CONFIG_CPU_PM */ 524 525 /* 526 * Ensure that the VFP state stored in 'thread->vfpstate' is up to date 527 * with the hardware state. 528 */ 529 void vfp_sync_hwstate(struct thread_info *thread) 530 { 531 unsigned int cpu = get_cpu(); 532 533 if (vfp_state_in_hw(cpu, thread)) { 534 u32 fpexc = fmrx(FPEXC); 535 536 /* 537 * Save the last VFP state on this CPU. 538 */ 539 fmxr(FPEXC, fpexc | FPEXC_EN); 540 vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN); 541 fmxr(FPEXC, fpexc); 542 } 543 544 put_cpu(); 545 } 546 547 /* Ensure that the thread reloads the hardware VFP state on the next use. */ 548 void vfp_flush_hwstate(struct thread_info *thread) 549 { 550 unsigned int cpu = get_cpu(); 551 552 vfp_force_reload(cpu, thread); 553 554 put_cpu(); 555 } 556 557 /* 558 * Save the current VFP state into the provided structures and prepare 559 * for entry into a new function (signal handler). 560 */ 561 int vfp_preserve_user_clear_hwstate(struct user_vfp __user *ufp, 562 struct user_vfp_exc __user *ufp_exc) 563 { 564 struct thread_info *thread = current_thread_info(); 565 struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; 566 int err = 0; 567 568 /* Ensure that the saved hwstate is up-to-date. */ 569 vfp_sync_hwstate(thread); 570 571 /* 572 * Copy the floating point registers. There can be unused 573 * registers see asm/hwcap.h for details. 574 */ 575 err |= __copy_to_user(&ufp->fpregs, &hwstate->fpregs, 576 sizeof(hwstate->fpregs)); 577 /* 578 * Copy the status and control register. 579 */ 580 __put_user_error(hwstate->fpscr, &ufp->fpscr, err); 581 582 /* 583 * Copy the exception registers. 584 */ 585 __put_user_error(hwstate->fpexc, &ufp_exc->fpexc, err); 586 __put_user_error(hwstate->fpinst, &ufp_exc->fpinst, err); 587 __put_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err); 588 589 if (err) 590 return -EFAULT; 591 592 /* Ensure that VFP is disabled. */ 593 vfp_flush_hwstate(thread); 594 595 /* 596 * As per the PCS, clear the length and stride bits for function 597 * entry. 598 */ 599 hwstate->fpscr &= ~(FPSCR_LENGTH_MASK | FPSCR_STRIDE_MASK); 600 return 0; 601 } 602 603 /* Sanitise and restore the current VFP state from the provided structures. */ 604 int vfp_restore_user_hwstate(struct user_vfp __user *ufp, 605 struct user_vfp_exc __user *ufp_exc) 606 { 607 struct thread_info *thread = current_thread_info(); 608 struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; 609 unsigned long fpexc; 610 int err = 0; 611 612 /* Disable VFP to avoid corrupting the new thread state. */ 613 vfp_flush_hwstate(thread); 614 615 /* 616 * Copy the floating point registers. There can be unused 617 * registers see asm/hwcap.h for details. 618 */ 619 err |= __copy_from_user(&hwstate->fpregs, &ufp->fpregs, 620 sizeof(hwstate->fpregs)); 621 /* 622 * Copy the status and control register. 623 */ 624 __get_user_error(hwstate->fpscr, &ufp->fpscr, err); 625 626 /* 627 * Sanitise and restore the exception registers. 628 */ 629 __get_user_error(fpexc, &ufp_exc->fpexc, err); 630 631 /* Ensure the VFP is enabled. */ 632 fpexc |= FPEXC_EN; 633 634 /* Ensure FPINST2 is invalid and the exception flag is cleared. */ 635 fpexc &= ~(FPEXC_EX | FPEXC_FP2V); 636 hwstate->fpexc = fpexc; 637 638 __get_user_error(hwstate->fpinst, &ufp_exc->fpinst, err); 639 __get_user_error(hwstate->fpinst2, &ufp_exc->fpinst2, err); 640 641 return err ? -EFAULT : 0; 642 } 643 644 /* 645 * VFP hardware can lose all context when a CPU goes offline. 646 * As we will be running in SMP mode with CPU hotplug, we will save the 647 * hardware state at every thread switch. We clear our held state when 648 * a CPU has been killed, indicating that the VFP hardware doesn't contain 649 * a threads VFP state. When a CPU starts up, we re-enable access to the 650 * VFP hardware. 651 * 652 * Both CPU_DYING and CPU_STARTING are called on the CPU which 653 * is being offlined/onlined. 654 */ 655 static int vfp_hotplug(struct notifier_block *b, unsigned long action, 656 void *hcpu) 657 { 658 if (action == CPU_DYING || action == CPU_DYING_FROZEN) 659 vfp_current_hw_state[(long)hcpu] = NULL; 660 else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN) 661 vfp_enable(NULL); 662 return NOTIFY_OK; 663 } 664 665 void vfp_kmode_exception(void) 666 { 667 /* 668 * If we reach this point, a floating point exception has been raised 669 * while running in kernel mode. If the NEON/VFP unit was enabled at the 670 * time, it means a VFP instruction has been issued that requires 671 * software assistance to complete, something which is not currently 672 * supported in kernel mode. 673 * If the NEON/VFP unit was disabled, and the location pointed to below 674 * is properly preceded by a call to kernel_neon_begin(), something has 675 * caused the task to be scheduled out and back in again. In this case, 676 * rebuilding and running with CONFIG_DEBUG_ATOMIC_SLEEP enabled should 677 * be helpful in localizing the problem. 678 */ 679 if (fmrx(FPEXC) & FPEXC_EN) 680 pr_crit("BUG: unsupported FP instruction in kernel mode\n"); 681 else 682 pr_crit("BUG: FP instruction issued in kernel mode with FP unit disabled\n"); 683 } 684 685 #ifdef CONFIG_KERNEL_MODE_NEON 686 687 /* 688 * Kernel-side NEON support functions 689 */ 690 void kernel_neon_begin(void) 691 { 692 struct thread_info *thread = current_thread_info(); 693 unsigned int cpu; 694 u32 fpexc; 695 696 /* 697 * Kernel mode NEON is only allowed outside of interrupt context 698 * with preemption disabled. This will make sure that the kernel 699 * mode NEON register contents never need to be preserved. 700 */ 701 BUG_ON(in_interrupt()); 702 cpu = get_cpu(); 703 704 fpexc = fmrx(FPEXC) | FPEXC_EN; 705 fmxr(FPEXC, fpexc); 706 707 /* 708 * Save the userland NEON/VFP state. Under UP, 709 * the owner could be a task other than 'current' 710 */ 711 if (vfp_state_in_hw(cpu, thread)) 712 vfp_save_state(&thread->vfpstate, fpexc); 713 #ifndef CONFIG_SMP 714 else if (vfp_current_hw_state[cpu] != NULL) 715 vfp_save_state(vfp_current_hw_state[cpu], fpexc); 716 #endif 717 vfp_current_hw_state[cpu] = NULL; 718 } 719 EXPORT_SYMBOL(kernel_neon_begin); 720 721 void kernel_neon_end(void) 722 { 723 /* Disable the NEON/VFP unit. */ 724 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 725 put_cpu(); 726 } 727 EXPORT_SYMBOL(kernel_neon_end); 728 729 #endif /* CONFIG_KERNEL_MODE_NEON */ 730 731 /* 732 * VFP support code initialisation. 733 */ 734 static int __init vfp_init(void) 735 { 736 unsigned int vfpsid; 737 unsigned int cpu_arch = cpu_architecture(); 738 739 if (cpu_arch >= CPU_ARCH_ARMv6) 740 on_each_cpu(vfp_enable, NULL, 1); 741 742 /* 743 * First check that there is a VFP that we can use. 744 * The handler is already setup to just log calls, so 745 * we just need to read the VFPSID register. 746 */ 747 vfp_vector = vfp_testing_entry; 748 barrier(); 749 vfpsid = fmrx(FPSID); 750 barrier(); 751 vfp_vector = vfp_null_entry; 752 753 pr_info("VFP support v0.3: "); 754 if (VFP_arch) { 755 pr_cont("not present\n"); 756 return 0; 757 /* Extract the architecture on CPUID scheme */ 758 } else if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) { 759 VFP_arch = vfpsid & FPSID_CPUID_ARCH_MASK; 760 VFP_arch >>= FPSID_ARCH_BIT; 761 /* 762 * Check for the presence of the Advanced SIMD 763 * load/store instructions, integer and single 764 * precision floating point operations. Only check 765 * for NEON if the hardware has the MVFR registers. 766 */ 767 if (IS_ENABLED(CONFIG_NEON) && 768 (fmrx(MVFR1) & 0x000fff00) == 0x00011100) 769 elf_hwcap |= HWCAP_NEON; 770 771 if (IS_ENABLED(CONFIG_VFPv3)) { 772 u32 mvfr0 = fmrx(MVFR0); 773 if (((mvfr0 & MVFR0_DP_MASK) >> MVFR0_DP_BIT) == 0x2 || 774 ((mvfr0 & MVFR0_SP_MASK) >> MVFR0_SP_BIT) == 0x2) { 775 elf_hwcap |= HWCAP_VFPv3; 776 /* 777 * Check for VFPv3 D16 and VFPv4 D16. CPUs in 778 * this configuration only have 16 x 64bit 779 * registers. 780 */ 781 if ((mvfr0 & MVFR0_A_SIMD_MASK) == 1) 782 /* also v4-D16 */ 783 elf_hwcap |= HWCAP_VFPv3D16; 784 else 785 elf_hwcap |= HWCAP_VFPD32; 786 } 787 788 if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000) 789 elf_hwcap |= HWCAP_VFPv4; 790 } 791 /* Extract the architecture version on pre-cpuid scheme */ 792 } else { 793 if (vfpsid & FPSID_NODOUBLE) { 794 pr_cont("no double precision support\n"); 795 return 0; 796 } 797 798 VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; 799 } 800 801 hotcpu_notifier(vfp_hotplug, 0); 802 803 vfp_vector = vfp_support_entry; 804 805 thread_register_notifier(&vfp_notifier_block); 806 vfp_pm_init(); 807 808 /* 809 * We detected VFP, and the support code is 810 * in place; report VFP support to userspace. 811 */ 812 elf_hwcap |= HWCAP_VFP; 813 814 pr_cont("implementor %02x architecture %d part %02x variant %x rev %x\n", 815 (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT, 816 VFP_arch, 817 (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT, 818 (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT, 819 (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT); 820 821 return 0; 822 } 823 824 core_initcall(vfp_init); 825