1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/arch/arm/vfp/vfpmodule.c 4 * 5 * Copyright (C) 2004 ARM Limited. 6 * Written by Deep Blue Solutions Limited. 7 */ 8 #include <linux/types.h> 9 #include <linux/cpu.h> 10 #include <linux/cpu_pm.h> 11 #include <linux/hardirq.h> 12 #include <linux/kernel.h> 13 #include <linux/notifier.h> 14 #include <linux/signal.h> 15 #include <linux/sched/signal.h> 16 #include <linux/smp.h> 17 #include <linux/init.h> 18 #include <linux/uaccess.h> 19 #include <linux/user.h> 20 #include <linux/export.h> 21 22 #include <asm/cp15.h> 23 #include <asm/cputype.h> 24 #include <asm/system_info.h> 25 #include <asm/thread_notify.h> 26 #include <asm/vfp.h> 27 28 #include "vfpinstr.h" 29 #include "vfp.h" 30 31 /* 32 * Our undef handlers (in entry.S) 33 */ 34 asmlinkage void vfp_testing_entry(void); 35 asmlinkage void vfp_support_entry(void); 36 asmlinkage void vfp_null_entry(void); 37 38 asmlinkage void (*vfp_vector)(void) = vfp_null_entry; 39 40 /* 41 * Dual-use variable. 42 * Used in startup: set to non-zero if VFP checks fail 43 * After startup, holds VFP architecture 44 */ 45 unsigned int VFP_arch; 46 47 /* 48 * The pointer to the vfpstate structure of the thread which currently 49 * owns the context held in the VFP hardware, or NULL if the hardware 50 * context is invalid. 51 * 52 * For UP, this is sufficient to tell which thread owns the VFP context. 53 * However, for SMP, we also need to check the CPU number stored in the 54 * saved state too to catch migrations. 55 */ 56 union vfp_state *vfp_current_hw_state[NR_CPUS]; 57 58 /* 59 * Is 'thread's most up to date state stored in this CPUs hardware? 60 * Must be called from non-preemptible context. 61 */ 62 static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread) 63 { 64 #ifdef CONFIG_SMP 65 if (thread->vfpstate.hard.cpu != cpu) 66 return false; 67 #endif 68 return vfp_current_hw_state[cpu] == &thread->vfpstate; 69 } 70 71 /* 72 * Force a reload of the VFP context from the thread structure. We do 73 * this by ensuring that access to the VFP hardware is disabled, and 74 * clear vfp_current_hw_state. Must be called from non-preemptible context. 75 */ 76 static void vfp_force_reload(unsigned int cpu, struct thread_info *thread) 77 { 78 if (vfp_state_in_hw(cpu, thread)) { 79 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 80 vfp_current_hw_state[cpu] = NULL; 81 } 82 #ifdef CONFIG_SMP 83 thread->vfpstate.hard.cpu = NR_CPUS; 84 #endif 85 } 86 87 /* 88 * Per-thread VFP initialization. 89 */ 90 static void vfp_thread_flush(struct thread_info *thread) 91 { 92 union vfp_state *vfp = &thread->vfpstate; 93 unsigned int cpu; 94 95 /* 96 * Disable VFP to ensure we initialize it first. We must ensure 97 * that the modification of vfp_current_hw_state[] and hardware 98 * disable are done for the same CPU and without preemption. 99 * 100 * Do this first to ensure that preemption won't overwrite our 101 * state saving should access to the VFP be enabled at this point. 102 */ 103 cpu = get_cpu(); 104 if (vfp_current_hw_state[cpu] == vfp) 105 vfp_current_hw_state[cpu] = NULL; 106 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 107 put_cpu(); 108 109 memset(vfp, 0, sizeof(union vfp_state)); 110 111 vfp->hard.fpexc = FPEXC_EN; 112 vfp->hard.fpscr = FPSCR_ROUND_NEAREST; 113 #ifdef CONFIG_SMP 114 vfp->hard.cpu = NR_CPUS; 115 #endif 116 } 117 118 static void vfp_thread_exit(struct thread_info *thread) 119 { 120 /* release case: Per-thread VFP cleanup. */ 121 union vfp_state *vfp = &thread->vfpstate; 122 unsigned int cpu = get_cpu(); 123 124 if (vfp_current_hw_state[cpu] == vfp) 125 vfp_current_hw_state[cpu] = NULL; 126 put_cpu(); 127 } 128 129 static void vfp_thread_copy(struct thread_info *thread) 130 { 131 struct thread_info *parent = current_thread_info(); 132 133 vfp_sync_hwstate(parent); 134 thread->vfpstate = parent->vfpstate; 135 #ifdef CONFIG_SMP 136 thread->vfpstate.hard.cpu = NR_CPUS; 137 #endif 138 } 139 140 /* 141 * When this function is called with the following 'cmd's, the following 142 * is true while this function is being run: 143 * THREAD_NOFTIFY_SWTICH: 144 * - the previously running thread will not be scheduled onto another CPU. 145 * - the next thread to be run (v) will not be running on another CPU. 146 * - thread->cpu is the local CPU number 147 * - not preemptible as we're called in the middle of a thread switch 148 * THREAD_NOTIFY_FLUSH: 149 * - the thread (v) will be running on the local CPU, so 150 * v === current_thread_info() 151 * - thread->cpu is the local CPU number at the time it is accessed, 152 * but may change at any time. 153 * - we could be preempted if tree preempt rcu is enabled, so 154 * it is unsafe to use thread->cpu. 155 * THREAD_NOTIFY_EXIT 156 * - we could be preempted if tree preempt rcu is enabled, so 157 * it is unsafe to use thread->cpu. 158 */ 159 static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v) 160 { 161 struct thread_info *thread = v; 162 u32 fpexc; 163 #ifdef CONFIG_SMP 164 unsigned int cpu; 165 #endif 166 167 switch (cmd) { 168 case THREAD_NOTIFY_SWITCH: 169 fpexc = fmrx(FPEXC); 170 171 #ifdef CONFIG_SMP 172 cpu = thread->cpu; 173 174 /* 175 * On SMP, if VFP is enabled, save the old state in 176 * case the thread migrates to a different CPU. The 177 * restoring is done lazily. 178 */ 179 if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) 180 vfp_save_state(vfp_current_hw_state[cpu], fpexc); 181 #endif 182 183 /* 184 * Always disable VFP so we can lazily save/restore the 185 * old state. 186 */ 187 fmxr(FPEXC, fpexc & ~FPEXC_EN); 188 break; 189 190 case THREAD_NOTIFY_FLUSH: 191 vfp_thread_flush(thread); 192 break; 193 194 case THREAD_NOTIFY_EXIT: 195 vfp_thread_exit(thread); 196 break; 197 198 case THREAD_NOTIFY_COPY: 199 vfp_thread_copy(thread); 200 break; 201 } 202 203 return NOTIFY_DONE; 204 } 205 206 static struct notifier_block vfp_notifier_block = { 207 .notifier_call = vfp_notifier, 208 }; 209 210 /* 211 * Raise a SIGFPE for the current process. 212 * sicode describes the signal being raised. 213 */ 214 static void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs) 215 { 216 /* 217 * This is the same as NWFPE, because it's not clear what 218 * this is used for 219 */ 220 current->thread.error_code = 0; 221 current->thread.trap_no = 6; 222 223 send_sig_fault(SIGFPE, sicode, 224 (void __user *)(instruction_pointer(regs) - 4), 225 current); 226 } 227 228 static void vfp_panic(char *reason, u32 inst) 229 { 230 int i; 231 232 pr_err("VFP: Error: %s\n", reason); 233 pr_err("VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x\n", 234 fmrx(FPEXC), fmrx(FPSCR), inst); 235 for (i = 0; i < 32; i += 2) 236 pr_err("VFP: s%2u: 0x%08x s%2u: 0x%08x\n", 237 i, vfp_get_float(i), i+1, vfp_get_float(i+1)); 238 } 239 240 /* 241 * Process bitmask of exception conditions. 242 */ 243 static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs) 244 { 245 int si_code = 0; 246 247 pr_debug("VFP: raising exceptions %08x\n", exceptions); 248 249 if (exceptions == VFP_EXCEPTION_ERROR) { 250 vfp_panic("unhandled bounce", inst); 251 vfp_raise_sigfpe(FPE_FLTINV, regs); 252 return; 253 } 254 255 /* 256 * If any of the status flags are set, update the FPSCR. 257 * Comparison instructions always return at least one of 258 * these flags set. 259 */ 260 if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V)) 261 fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V); 262 263 fpscr |= exceptions; 264 265 fmxr(FPSCR, fpscr); 266 267 #define RAISE(stat,en,sig) \ 268 if (exceptions & stat && fpscr & en) \ 269 si_code = sig; 270 271 /* 272 * These are arranged in priority order, least to highest. 273 */ 274 RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV); 275 RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES); 276 RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND); 277 RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF); 278 RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV); 279 280 if (si_code) 281 vfp_raise_sigfpe(si_code, regs); 282 } 283 284 /* 285 * Emulate a VFP instruction. 286 */ 287 static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs) 288 { 289 u32 exceptions = VFP_EXCEPTION_ERROR; 290 291 pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x\n", inst, fpscr); 292 293 if (INST_CPRTDO(inst)) { 294 if (!INST_CPRT(inst)) { 295 /* 296 * CPDO 297 */ 298 if (vfp_single(inst)) { 299 exceptions = vfp_single_cpdo(inst, fpscr); 300 } else { 301 exceptions = vfp_double_cpdo(inst, fpscr); 302 } 303 } else { 304 /* 305 * A CPRT instruction can not appear in FPINST2, nor 306 * can it cause an exception. Therefore, we do not 307 * have to emulate it. 308 */ 309 } 310 } else { 311 /* 312 * A CPDT instruction can not appear in FPINST2, nor can 313 * it cause an exception. Therefore, we do not have to 314 * emulate it. 315 */ 316 } 317 return exceptions & ~VFP_NAN_FLAG; 318 } 319 320 /* 321 * Package up a bounce condition. 322 */ 323 void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs) 324 { 325 u32 fpscr, orig_fpscr, fpsid, exceptions; 326 327 pr_debug("VFP: bounce: trigger %08x fpexc %08x\n", trigger, fpexc); 328 329 /* 330 * At this point, FPEXC can have the following configuration: 331 * 332 * EX DEX IXE 333 * 0 1 x - synchronous exception 334 * 1 x 0 - asynchronous exception 335 * 1 x 1 - sychronous on VFP subarch 1 and asynchronous on later 336 * 0 0 1 - synchronous on VFP9 (non-standard subarch 1 337 * implementation), undefined otherwise 338 * 339 * Clear various bits and enable access to the VFP so we can 340 * handle the bounce. 341 */ 342 fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK)); 343 344 fpsid = fmrx(FPSID); 345 orig_fpscr = fpscr = fmrx(FPSCR); 346 347 /* 348 * Check for the special VFP subarch 1 and FPSCR.IXE bit case 349 */ 350 if ((fpsid & FPSID_ARCH_MASK) == (1 << FPSID_ARCH_BIT) 351 && (fpscr & FPSCR_IXE)) { 352 /* 353 * Synchronous exception, emulate the trigger instruction 354 */ 355 goto emulate; 356 } 357 358 if (fpexc & FPEXC_EX) { 359 #ifndef CONFIG_CPU_FEROCEON 360 /* 361 * Asynchronous exception. The instruction is read from FPINST 362 * and the interrupted instruction has to be restarted. 363 */ 364 trigger = fmrx(FPINST); 365 regs->ARM_pc -= 4; 366 #endif 367 } else if (!(fpexc & FPEXC_DEX)) { 368 /* 369 * Illegal combination of bits. It can be caused by an 370 * unallocated VFP instruction but with FPSCR.IXE set and not 371 * on VFP subarch 1. 372 */ 373 vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs); 374 goto exit; 375 } 376 377 /* 378 * Modify fpscr to indicate the number of iterations remaining. 379 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates 380 * whether FPEXC.VECITR or FPSCR.LEN is used. 381 */ 382 if (fpexc & (FPEXC_EX | FPEXC_VV)) { 383 u32 len; 384 385 len = fpexc + (1 << FPEXC_LENGTH_BIT); 386 387 fpscr &= ~FPSCR_LENGTH_MASK; 388 fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT); 389 } 390 391 /* 392 * Handle the first FP instruction. We used to take note of the 393 * FPEXC bounce reason, but this appears to be unreliable. 394 * Emulate the bounced instruction instead. 395 */ 396 exceptions = vfp_emulate_instruction(trigger, fpscr, regs); 397 if (exceptions) 398 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 399 400 /* 401 * If there isn't a second FP instruction, exit now. Note that 402 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1. 403 */ 404 if ((fpexc & (FPEXC_EX | FPEXC_FP2V)) != (FPEXC_EX | FPEXC_FP2V)) 405 goto exit; 406 407 /* 408 * The barrier() here prevents fpinst2 being read 409 * before the condition above. 410 */ 411 barrier(); 412 trigger = fmrx(FPINST2); 413 414 emulate: 415 exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs); 416 if (exceptions) 417 vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs); 418 exit: 419 preempt_enable(); 420 } 421 422 static void vfp_enable(void *unused) 423 { 424 u32 access; 425 426 BUG_ON(preemptible()); 427 access = get_copro_access(); 428 429 /* 430 * Enable full access to VFP (cp10 and cp11) 431 */ 432 set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11)); 433 } 434 435 /* Called by platforms on which we want to disable VFP because it may not be 436 * present on all CPUs within a SMP complex. Needs to be called prior to 437 * vfp_init(). 438 */ 439 void vfp_disable(void) 440 { 441 if (VFP_arch) { 442 pr_debug("%s: should be called prior to vfp_init\n", __func__); 443 return; 444 } 445 VFP_arch = 1; 446 } 447 448 #ifdef CONFIG_CPU_PM 449 static int vfp_pm_suspend(void) 450 { 451 struct thread_info *ti = current_thread_info(); 452 u32 fpexc = fmrx(FPEXC); 453 454 /* if vfp is on, then save state for resumption */ 455 if (fpexc & FPEXC_EN) { 456 pr_debug("%s: saving vfp state\n", __func__); 457 vfp_save_state(&ti->vfpstate, fpexc); 458 459 /* disable, just in case */ 460 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 461 } else if (vfp_current_hw_state[ti->cpu]) { 462 #ifndef CONFIG_SMP 463 fmxr(FPEXC, fpexc | FPEXC_EN); 464 vfp_save_state(vfp_current_hw_state[ti->cpu], fpexc); 465 fmxr(FPEXC, fpexc); 466 #endif 467 } 468 469 /* clear any information we had about last context state */ 470 vfp_current_hw_state[ti->cpu] = NULL; 471 472 return 0; 473 } 474 475 static void vfp_pm_resume(void) 476 { 477 /* ensure we have access to the vfp */ 478 vfp_enable(NULL); 479 480 /* and disable it to ensure the next usage restores the state */ 481 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 482 } 483 484 static int vfp_cpu_pm_notifier(struct notifier_block *self, unsigned long cmd, 485 void *v) 486 { 487 switch (cmd) { 488 case CPU_PM_ENTER: 489 vfp_pm_suspend(); 490 break; 491 case CPU_PM_ENTER_FAILED: 492 case CPU_PM_EXIT: 493 vfp_pm_resume(); 494 break; 495 } 496 return NOTIFY_OK; 497 } 498 499 static struct notifier_block vfp_cpu_pm_notifier_block = { 500 .notifier_call = vfp_cpu_pm_notifier, 501 }; 502 503 static void vfp_pm_init(void) 504 { 505 cpu_pm_register_notifier(&vfp_cpu_pm_notifier_block); 506 } 507 508 #else 509 static inline void vfp_pm_init(void) { } 510 #endif /* CONFIG_CPU_PM */ 511 512 /* 513 * Ensure that the VFP state stored in 'thread->vfpstate' is up to date 514 * with the hardware state. 515 */ 516 void vfp_sync_hwstate(struct thread_info *thread) 517 { 518 unsigned int cpu = get_cpu(); 519 520 if (vfp_state_in_hw(cpu, thread)) { 521 u32 fpexc = fmrx(FPEXC); 522 523 /* 524 * Save the last VFP state on this CPU. 525 */ 526 fmxr(FPEXC, fpexc | FPEXC_EN); 527 vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN); 528 fmxr(FPEXC, fpexc); 529 } 530 531 put_cpu(); 532 } 533 534 /* Ensure that the thread reloads the hardware VFP state on the next use. */ 535 void vfp_flush_hwstate(struct thread_info *thread) 536 { 537 unsigned int cpu = get_cpu(); 538 539 vfp_force_reload(cpu, thread); 540 541 put_cpu(); 542 } 543 544 /* 545 * Save the current VFP state into the provided structures and prepare 546 * for entry into a new function (signal handler). 547 */ 548 int vfp_preserve_user_clear_hwstate(struct user_vfp *ufp, 549 struct user_vfp_exc *ufp_exc) 550 { 551 struct thread_info *thread = current_thread_info(); 552 struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; 553 554 /* Ensure that the saved hwstate is up-to-date. */ 555 vfp_sync_hwstate(thread); 556 557 /* 558 * Copy the floating point registers. There can be unused 559 * registers see asm/hwcap.h for details. 560 */ 561 memcpy(&ufp->fpregs, &hwstate->fpregs, sizeof(hwstate->fpregs)); 562 563 /* 564 * Copy the status and control register. 565 */ 566 ufp->fpscr = hwstate->fpscr; 567 568 /* 569 * Copy the exception registers. 570 */ 571 ufp_exc->fpexc = hwstate->fpexc; 572 ufp_exc->fpinst = hwstate->fpinst; 573 ufp_exc->fpinst2 = hwstate->fpinst2; 574 575 /* Ensure that VFP is disabled. */ 576 vfp_flush_hwstate(thread); 577 578 /* 579 * As per the PCS, clear the length and stride bits for function 580 * entry. 581 */ 582 hwstate->fpscr &= ~(FPSCR_LENGTH_MASK | FPSCR_STRIDE_MASK); 583 return 0; 584 } 585 586 /* Sanitise and restore the current VFP state from the provided structures. */ 587 int vfp_restore_user_hwstate(struct user_vfp *ufp, struct user_vfp_exc *ufp_exc) 588 { 589 struct thread_info *thread = current_thread_info(); 590 struct vfp_hard_struct *hwstate = &thread->vfpstate.hard; 591 unsigned long fpexc; 592 593 /* Disable VFP to avoid corrupting the new thread state. */ 594 vfp_flush_hwstate(thread); 595 596 /* 597 * Copy the floating point registers. There can be unused 598 * registers see asm/hwcap.h for details. 599 */ 600 memcpy(&hwstate->fpregs, &ufp->fpregs, sizeof(hwstate->fpregs)); 601 /* 602 * Copy the status and control register. 603 */ 604 hwstate->fpscr = ufp->fpscr; 605 606 /* 607 * Sanitise and restore the exception registers. 608 */ 609 fpexc = ufp_exc->fpexc; 610 611 /* Ensure the VFP is enabled. */ 612 fpexc |= FPEXC_EN; 613 614 /* Ensure FPINST2 is invalid and the exception flag is cleared. */ 615 fpexc &= ~(FPEXC_EX | FPEXC_FP2V); 616 hwstate->fpexc = fpexc; 617 618 hwstate->fpinst = ufp_exc->fpinst; 619 hwstate->fpinst2 = ufp_exc->fpinst2; 620 621 return 0; 622 } 623 624 /* 625 * VFP hardware can lose all context when a CPU goes offline. 626 * As we will be running in SMP mode with CPU hotplug, we will save the 627 * hardware state at every thread switch. We clear our held state when 628 * a CPU has been killed, indicating that the VFP hardware doesn't contain 629 * a threads VFP state. When a CPU starts up, we re-enable access to the 630 * VFP hardware. The callbacks below are called on the CPU which 631 * is being offlined/onlined. 632 */ 633 static int vfp_dying_cpu(unsigned int cpu) 634 { 635 vfp_current_hw_state[cpu] = NULL; 636 return 0; 637 } 638 639 static int vfp_starting_cpu(unsigned int unused) 640 { 641 vfp_enable(NULL); 642 return 0; 643 } 644 645 void vfp_kmode_exception(void) 646 { 647 /* 648 * If we reach this point, a floating point exception has been raised 649 * while running in kernel mode. If the NEON/VFP unit was enabled at the 650 * time, it means a VFP instruction has been issued that requires 651 * software assistance to complete, something which is not currently 652 * supported in kernel mode. 653 * If the NEON/VFP unit was disabled, and the location pointed to below 654 * is properly preceded by a call to kernel_neon_begin(), something has 655 * caused the task to be scheduled out and back in again. In this case, 656 * rebuilding and running with CONFIG_DEBUG_ATOMIC_SLEEP enabled should 657 * be helpful in localizing the problem. 658 */ 659 if (fmrx(FPEXC) & FPEXC_EN) 660 pr_crit("BUG: unsupported FP instruction in kernel mode\n"); 661 else 662 pr_crit("BUG: FP instruction issued in kernel mode with FP unit disabled\n"); 663 } 664 665 #ifdef CONFIG_KERNEL_MODE_NEON 666 667 /* 668 * Kernel-side NEON support functions 669 */ 670 void kernel_neon_begin(void) 671 { 672 struct thread_info *thread = current_thread_info(); 673 unsigned int cpu; 674 u32 fpexc; 675 676 /* 677 * Kernel mode NEON is only allowed outside of interrupt context 678 * with preemption disabled. This will make sure that the kernel 679 * mode NEON register contents never need to be preserved. 680 */ 681 BUG_ON(in_interrupt()); 682 cpu = get_cpu(); 683 684 fpexc = fmrx(FPEXC) | FPEXC_EN; 685 fmxr(FPEXC, fpexc); 686 687 /* 688 * Save the userland NEON/VFP state. Under UP, 689 * the owner could be a task other than 'current' 690 */ 691 if (vfp_state_in_hw(cpu, thread)) 692 vfp_save_state(&thread->vfpstate, fpexc); 693 #ifndef CONFIG_SMP 694 else if (vfp_current_hw_state[cpu] != NULL) 695 vfp_save_state(vfp_current_hw_state[cpu], fpexc); 696 #endif 697 vfp_current_hw_state[cpu] = NULL; 698 } 699 EXPORT_SYMBOL(kernel_neon_begin); 700 701 void kernel_neon_end(void) 702 { 703 /* Disable the NEON/VFP unit. */ 704 fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN); 705 put_cpu(); 706 } 707 EXPORT_SYMBOL(kernel_neon_end); 708 709 #endif /* CONFIG_KERNEL_MODE_NEON */ 710 711 /* 712 * VFP support code initialisation. 713 */ 714 static int __init vfp_init(void) 715 { 716 unsigned int vfpsid; 717 unsigned int cpu_arch = cpu_architecture(); 718 719 /* 720 * Enable the access to the VFP on all online CPUs so the 721 * following test on FPSID will succeed. 722 */ 723 if (cpu_arch >= CPU_ARCH_ARMv6) 724 on_each_cpu(vfp_enable, NULL, 1); 725 726 /* 727 * First check that there is a VFP that we can use. 728 * The handler is already setup to just log calls, so 729 * we just need to read the VFPSID register. 730 */ 731 vfp_vector = vfp_testing_entry; 732 barrier(); 733 vfpsid = fmrx(FPSID); 734 barrier(); 735 vfp_vector = vfp_null_entry; 736 737 pr_info("VFP support v0.3: "); 738 if (VFP_arch) { 739 pr_cont("not present\n"); 740 return 0; 741 /* Extract the architecture on CPUID scheme */ 742 } else if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) { 743 VFP_arch = vfpsid & FPSID_CPUID_ARCH_MASK; 744 VFP_arch >>= FPSID_ARCH_BIT; 745 /* 746 * Check for the presence of the Advanced SIMD 747 * load/store instructions, integer and single 748 * precision floating point operations. Only check 749 * for NEON if the hardware has the MVFR registers. 750 */ 751 if (IS_ENABLED(CONFIG_NEON) && 752 (fmrx(MVFR1) & 0x000fff00) == 0x00011100) 753 elf_hwcap |= HWCAP_NEON; 754 755 if (IS_ENABLED(CONFIG_VFPv3)) { 756 u32 mvfr0 = fmrx(MVFR0); 757 if (((mvfr0 & MVFR0_DP_MASK) >> MVFR0_DP_BIT) == 0x2 || 758 ((mvfr0 & MVFR0_SP_MASK) >> MVFR0_SP_BIT) == 0x2) { 759 elf_hwcap |= HWCAP_VFPv3; 760 /* 761 * Check for VFPv3 D16 and VFPv4 D16. CPUs in 762 * this configuration only have 16 x 64bit 763 * registers. 764 */ 765 if ((mvfr0 & MVFR0_A_SIMD_MASK) == 1) 766 /* also v4-D16 */ 767 elf_hwcap |= HWCAP_VFPv3D16; 768 else 769 elf_hwcap |= HWCAP_VFPD32; 770 } 771 772 if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000) 773 elf_hwcap |= HWCAP_VFPv4; 774 } 775 /* Extract the architecture version on pre-cpuid scheme */ 776 } else { 777 if (vfpsid & FPSID_NODOUBLE) { 778 pr_cont("no double precision support\n"); 779 return 0; 780 } 781 782 VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT; 783 } 784 785 cpuhp_setup_state_nocalls(CPUHP_AP_ARM_VFP_STARTING, 786 "arm/vfp:starting", vfp_starting_cpu, 787 vfp_dying_cpu); 788 789 vfp_vector = vfp_support_entry; 790 791 thread_register_notifier(&vfp_notifier_block); 792 vfp_pm_init(); 793 794 /* 795 * We detected VFP, and the support code is 796 * in place; report VFP support to userspace. 797 */ 798 elf_hwcap |= HWCAP_VFP; 799 800 pr_cont("implementor %02x architecture %d part %02x variant %x rev %x\n", 801 (vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT, 802 VFP_arch, 803 (vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT, 804 (vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT, 805 (vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT); 806 807 return 0; 808 } 809 810 core_initcall(vfp_init); 811