1 // SPDX-License-Identifier: GPL-2.0 2 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 3 4 #include <linux/errno.h> 5 #include <linux/kernel.h> 6 #include <linux/mm.h> 7 #include <linux/smp.h> 8 #include <linux/prctl.h> 9 #include <linux/slab.h> 10 #include <linux/sched.h> 11 #include <linux/sched/idle.h> 12 #include <linux/sched/debug.h> 13 #include <linux/sched/task.h> 14 #include <linux/sched/task_stack.h> 15 #include <linux/init.h> 16 #include <linux/export.h> 17 #include <linux/pm.h> 18 #include <linux/tick.h> 19 #include <linux/random.h> 20 #include <linux/user-return-notifier.h> 21 #include <linux/dmi.h> 22 #include <linux/utsname.h> 23 #include <linux/stackprotector.h> 24 #include <linux/cpuidle.h> 25 #include <linux/acpi.h> 26 #include <linux/elf-randomize.h> 27 #include <trace/events/power.h> 28 #include <linux/hw_breakpoint.h> 29 #include <asm/cpu.h> 30 #include <asm/apic.h> 31 #include <asm/syscalls.h> 32 #include <linux/uaccess.h> 33 #include <asm/mwait.h> 34 #include <asm/fpu/internal.h> 35 #include <asm/debugreg.h> 36 #include <asm/nmi.h> 37 #include <asm/tlbflush.h> 38 #include <asm/mce.h> 39 #include <asm/vm86.h> 40 #include <asm/switch_to.h> 41 #include <asm/desc.h> 42 #include <asm/prctl.h> 43 #include <asm/spec-ctrl.h> 44 #include <asm/io_bitmap.h> 45 #include <asm/proto.h> 46 47 #include "process.h" 48 49 /* 50 * per-CPU TSS segments. Threads are completely 'soft' on Linux, 51 * no more per-task TSS's. The TSS size is kept cacheline-aligned 52 * so they are allowed to end up in the .data..cacheline_aligned 53 * section. Since TSS's are completely CPU-local, we want them 54 * on exact cacheline boundaries, to eliminate cacheline ping-pong. 55 */ 56 __visible DEFINE_PER_CPU_PAGE_ALIGNED(struct tss_struct, cpu_tss_rw) = { 57 .x86_tss = { 58 /* 59 * .sp0 is only used when entering ring 0 from a lower 60 * privilege level. Since the init task never runs anything 61 * but ring 0 code, there is no need for a valid value here. 62 * Poison it. 63 */ 64 .sp0 = (1UL << (BITS_PER_LONG-1)) + 1, 65 66 /* 67 * .sp1 is cpu_current_top_of_stack. The init task never 68 * runs user code, but cpu_current_top_of_stack should still 69 * be well defined before the first context switch. 70 */ 71 .sp1 = TOP_OF_INIT_STACK, 72 73 #ifdef CONFIG_X86_32 74 .ss0 = __KERNEL_DS, 75 .ss1 = __KERNEL_CS, 76 #endif 77 .io_bitmap_base = IO_BITMAP_OFFSET_INVALID, 78 }, 79 }; 80 EXPORT_PER_CPU_SYMBOL(cpu_tss_rw); 81 82 DEFINE_PER_CPU(bool, __tss_limit_invalid); 83 EXPORT_PER_CPU_SYMBOL_GPL(__tss_limit_invalid); 84 85 /* 86 * this gets called so that we can store lazy state into memory and copy the 87 * current task into the new thread. 88 */ 89 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) 90 { 91 memcpy(dst, src, arch_task_struct_size); 92 #ifdef CONFIG_VM86 93 dst->thread.vm86 = NULL; 94 #endif 95 96 return fpu__copy(dst, src); 97 } 98 99 /* 100 * Free current thread data structures etc.. 101 */ 102 void exit_thread(struct task_struct *tsk) 103 { 104 struct thread_struct *t = &tsk->thread; 105 struct fpu *fpu = &t->fpu; 106 107 if (test_thread_flag(TIF_IO_BITMAP)) 108 io_bitmap_exit(); 109 110 free_vm86(t); 111 112 fpu__drop(fpu); 113 } 114 115 static int set_new_tls(struct task_struct *p, unsigned long tls) 116 { 117 struct user_desc __user *utls = (struct user_desc __user *)tls; 118 119 if (in_ia32_syscall()) 120 return do_set_thread_area(p, -1, utls, 0); 121 else 122 return do_set_thread_area_64(p, ARCH_SET_FS, tls); 123 } 124 125 int copy_thread_tls(unsigned long clone_flags, unsigned long sp, 126 unsigned long arg, struct task_struct *p, unsigned long tls) 127 { 128 struct inactive_task_frame *frame; 129 struct fork_frame *fork_frame; 130 struct pt_regs *childregs; 131 int ret = 0; 132 133 childregs = task_pt_regs(p); 134 fork_frame = container_of(childregs, struct fork_frame, regs); 135 frame = &fork_frame->frame; 136 137 frame->bp = 0; 138 frame->ret_addr = (unsigned long) ret_from_fork; 139 p->thread.sp = (unsigned long) fork_frame; 140 p->thread.io_bitmap = NULL; 141 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps)); 142 143 #ifdef CONFIG_X86_64 144 savesegment(gs, p->thread.gsindex); 145 p->thread.gsbase = p->thread.gsindex ? 0 : current->thread.gsbase; 146 savesegment(fs, p->thread.fsindex); 147 p->thread.fsbase = p->thread.fsindex ? 0 : current->thread.fsbase; 148 savesegment(es, p->thread.es); 149 savesegment(ds, p->thread.ds); 150 #else 151 p->thread.sp0 = (unsigned long) (childregs + 1); 152 /* 153 * Clear all status flags including IF and set fixed bit. 64bit 154 * does not have this initialization as the frame does not contain 155 * flags. The flags consistency (especially vs. AC) is there 156 * ensured via objtool, which lacks 32bit support. 157 */ 158 frame->flags = X86_EFLAGS_FIXED; 159 #endif 160 161 /* Kernel thread ? */ 162 if (unlikely(p->flags & PF_KTHREAD)) { 163 memset(childregs, 0, sizeof(struct pt_regs)); 164 kthread_frame_init(frame, sp, arg); 165 return 0; 166 } 167 168 frame->bx = 0; 169 *childregs = *current_pt_regs(); 170 childregs->ax = 0; 171 if (sp) 172 childregs->sp = sp; 173 174 #ifdef CONFIG_X86_32 175 task_user_gs(p) = get_user_gs(current_pt_regs()); 176 #endif 177 178 /* Set a new TLS for the child thread? */ 179 if (clone_flags & CLONE_SETTLS) 180 ret = set_new_tls(p, tls); 181 182 if (!ret && unlikely(test_tsk_thread_flag(current, TIF_IO_BITMAP))) 183 io_bitmap_share(p); 184 185 return ret; 186 } 187 188 void flush_thread(void) 189 { 190 struct task_struct *tsk = current; 191 192 flush_ptrace_hw_breakpoint(tsk); 193 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); 194 195 fpu__clear(&tsk->thread.fpu); 196 } 197 198 void disable_TSC(void) 199 { 200 preempt_disable(); 201 if (!test_and_set_thread_flag(TIF_NOTSC)) 202 /* 203 * Must flip the CPU state synchronously with 204 * TIF_NOTSC in the current running context. 205 */ 206 cr4_set_bits(X86_CR4_TSD); 207 preempt_enable(); 208 } 209 210 static void enable_TSC(void) 211 { 212 preempt_disable(); 213 if (test_and_clear_thread_flag(TIF_NOTSC)) 214 /* 215 * Must flip the CPU state synchronously with 216 * TIF_NOTSC in the current running context. 217 */ 218 cr4_clear_bits(X86_CR4_TSD); 219 preempt_enable(); 220 } 221 222 int get_tsc_mode(unsigned long adr) 223 { 224 unsigned int val; 225 226 if (test_thread_flag(TIF_NOTSC)) 227 val = PR_TSC_SIGSEGV; 228 else 229 val = PR_TSC_ENABLE; 230 231 return put_user(val, (unsigned int __user *)adr); 232 } 233 234 int set_tsc_mode(unsigned int val) 235 { 236 if (val == PR_TSC_SIGSEGV) 237 disable_TSC(); 238 else if (val == PR_TSC_ENABLE) 239 enable_TSC(); 240 else 241 return -EINVAL; 242 243 return 0; 244 } 245 246 DEFINE_PER_CPU(u64, msr_misc_features_shadow); 247 248 static void set_cpuid_faulting(bool on) 249 { 250 u64 msrval; 251 252 msrval = this_cpu_read(msr_misc_features_shadow); 253 msrval &= ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT; 254 msrval |= (on << MSR_MISC_FEATURES_ENABLES_CPUID_FAULT_BIT); 255 this_cpu_write(msr_misc_features_shadow, msrval); 256 wrmsrl(MSR_MISC_FEATURES_ENABLES, msrval); 257 } 258 259 static void disable_cpuid(void) 260 { 261 preempt_disable(); 262 if (!test_and_set_thread_flag(TIF_NOCPUID)) { 263 /* 264 * Must flip the CPU state synchronously with 265 * TIF_NOCPUID in the current running context. 266 */ 267 set_cpuid_faulting(true); 268 } 269 preempt_enable(); 270 } 271 272 static void enable_cpuid(void) 273 { 274 preempt_disable(); 275 if (test_and_clear_thread_flag(TIF_NOCPUID)) { 276 /* 277 * Must flip the CPU state synchronously with 278 * TIF_NOCPUID in the current running context. 279 */ 280 set_cpuid_faulting(false); 281 } 282 preempt_enable(); 283 } 284 285 static int get_cpuid_mode(void) 286 { 287 return !test_thread_flag(TIF_NOCPUID); 288 } 289 290 static int set_cpuid_mode(struct task_struct *task, unsigned long cpuid_enabled) 291 { 292 if (!boot_cpu_has(X86_FEATURE_CPUID_FAULT)) 293 return -ENODEV; 294 295 if (cpuid_enabled) 296 enable_cpuid(); 297 else 298 disable_cpuid(); 299 300 return 0; 301 } 302 303 /* 304 * Called immediately after a successful exec. 305 */ 306 void arch_setup_new_exec(void) 307 { 308 /* If cpuid was previously disabled for this task, re-enable it. */ 309 if (test_thread_flag(TIF_NOCPUID)) 310 enable_cpuid(); 311 312 /* 313 * Don't inherit TIF_SSBD across exec boundary when 314 * PR_SPEC_DISABLE_NOEXEC is used. 315 */ 316 if (test_thread_flag(TIF_SSBD) && 317 task_spec_ssb_noexec(current)) { 318 clear_thread_flag(TIF_SSBD); 319 task_clear_spec_ssb_disable(current); 320 task_clear_spec_ssb_noexec(current); 321 speculation_ctrl_update(task_thread_info(current)->flags); 322 } 323 } 324 325 #ifdef CONFIG_X86_IOPL_IOPERM 326 static inline void tss_invalidate_io_bitmap(struct tss_struct *tss) 327 { 328 /* 329 * Invalidate the I/O bitmap by moving io_bitmap_base outside the 330 * TSS limit so any subsequent I/O access from user space will 331 * trigger a #GP. 332 * 333 * This is correct even when VMEXIT rewrites the TSS limit 334 * to 0x67 as the only requirement is that the base points 335 * outside the limit. 336 */ 337 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET_INVALID; 338 } 339 340 static inline void switch_to_bitmap(unsigned long tifp) 341 { 342 /* 343 * Invalidate I/O bitmap if the previous task used it. This prevents 344 * any possible leakage of an active I/O bitmap. 345 * 346 * If the next task has an I/O bitmap it will handle it on exit to 347 * user mode. 348 */ 349 if (tifp & _TIF_IO_BITMAP) 350 tss_invalidate_io_bitmap(this_cpu_ptr(&cpu_tss_rw)); 351 } 352 353 static void tss_copy_io_bitmap(struct tss_struct *tss, struct io_bitmap *iobm) 354 { 355 /* 356 * Copy at least the byte range of the incoming tasks bitmap which 357 * covers the permitted I/O ports. 358 * 359 * If the previous task which used an I/O bitmap had more bits 360 * permitted, then the copy needs to cover those as well so they 361 * get turned off. 362 */ 363 memcpy(tss->io_bitmap.bitmap, iobm->bitmap, 364 max(tss->io_bitmap.prev_max, iobm->max)); 365 366 /* 367 * Store the new max and the sequence number of this bitmap 368 * and a pointer to the bitmap itself. 369 */ 370 tss->io_bitmap.prev_max = iobm->max; 371 tss->io_bitmap.prev_sequence = iobm->sequence; 372 } 373 374 /** 375 * tss_update_io_bitmap - Update I/O bitmap before exiting to usermode 376 */ 377 void tss_update_io_bitmap(void) 378 { 379 struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw); 380 struct thread_struct *t = ¤t->thread; 381 u16 *base = &tss->x86_tss.io_bitmap_base; 382 383 if (!test_thread_flag(TIF_IO_BITMAP)) { 384 tss_invalidate_io_bitmap(tss); 385 return; 386 } 387 388 if (IS_ENABLED(CONFIG_X86_IOPL_IOPERM) && t->iopl_emul == 3) { 389 *base = IO_BITMAP_OFFSET_VALID_ALL; 390 } else { 391 struct io_bitmap *iobm = t->io_bitmap; 392 393 /* 394 * Only copy bitmap data when the sequence number differs. The 395 * update time is accounted to the incoming task. 396 */ 397 if (tss->io_bitmap.prev_sequence != iobm->sequence) 398 tss_copy_io_bitmap(tss, iobm); 399 400 /* Enable the bitmap */ 401 *base = IO_BITMAP_OFFSET_VALID_MAP; 402 } 403 404 /* 405 * Make sure that the TSS limit is covering the IO bitmap. It might have 406 * been cut down by a VMEXIT to 0x67 which would cause a subsequent I/O 407 * access from user space to trigger a #GP because tbe bitmap is outside 408 * the TSS limit. 409 */ 410 refresh_tss_limit(); 411 } 412 #else /* CONFIG_X86_IOPL_IOPERM */ 413 static inline void switch_to_bitmap(unsigned long tifp) { } 414 #endif 415 416 #ifdef CONFIG_SMP 417 418 struct ssb_state { 419 struct ssb_state *shared_state; 420 raw_spinlock_t lock; 421 unsigned int disable_state; 422 unsigned long local_state; 423 }; 424 425 #define LSTATE_SSB 0 426 427 static DEFINE_PER_CPU(struct ssb_state, ssb_state); 428 429 void speculative_store_bypass_ht_init(void) 430 { 431 struct ssb_state *st = this_cpu_ptr(&ssb_state); 432 unsigned int this_cpu = smp_processor_id(); 433 unsigned int cpu; 434 435 st->local_state = 0; 436 437 /* 438 * Shared state setup happens once on the first bringup 439 * of the CPU. It's not destroyed on CPU hotunplug. 440 */ 441 if (st->shared_state) 442 return; 443 444 raw_spin_lock_init(&st->lock); 445 446 /* 447 * Go over HT siblings and check whether one of them has set up the 448 * shared state pointer already. 449 */ 450 for_each_cpu(cpu, topology_sibling_cpumask(this_cpu)) { 451 if (cpu == this_cpu) 452 continue; 453 454 if (!per_cpu(ssb_state, cpu).shared_state) 455 continue; 456 457 /* Link it to the state of the sibling: */ 458 st->shared_state = per_cpu(ssb_state, cpu).shared_state; 459 return; 460 } 461 462 /* 463 * First HT sibling to come up on the core. Link shared state of 464 * the first HT sibling to itself. The siblings on the same core 465 * which come up later will see the shared state pointer and link 466 * themself to the state of this CPU. 467 */ 468 st->shared_state = st; 469 } 470 471 /* 472 * Logic is: First HT sibling enables SSBD for both siblings in the core 473 * and last sibling to disable it, disables it for the whole core. This how 474 * MSR_SPEC_CTRL works in "hardware": 475 * 476 * CORE_SPEC_CTRL = THREAD0_SPEC_CTRL | THREAD1_SPEC_CTRL 477 */ 478 static __always_inline void amd_set_core_ssb_state(unsigned long tifn) 479 { 480 struct ssb_state *st = this_cpu_ptr(&ssb_state); 481 u64 msr = x86_amd_ls_cfg_base; 482 483 if (!static_cpu_has(X86_FEATURE_ZEN)) { 484 msr |= ssbd_tif_to_amd_ls_cfg(tifn); 485 wrmsrl(MSR_AMD64_LS_CFG, msr); 486 return; 487 } 488 489 if (tifn & _TIF_SSBD) { 490 /* 491 * Since this can race with prctl(), block reentry on the 492 * same CPU. 493 */ 494 if (__test_and_set_bit(LSTATE_SSB, &st->local_state)) 495 return; 496 497 msr |= x86_amd_ls_cfg_ssbd_mask; 498 499 raw_spin_lock(&st->shared_state->lock); 500 /* First sibling enables SSBD: */ 501 if (!st->shared_state->disable_state) 502 wrmsrl(MSR_AMD64_LS_CFG, msr); 503 st->shared_state->disable_state++; 504 raw_spin_unlock(&st->shared_state->lock); 505 } else { 506 if (!__test_and_clear_bit(LSTATE_SSB, &st->local_state)) 507 return; 508 509 raw_spin_lock(&st->shared_state->lock); 510 st->shared_state->disable_state--; 511 if (!st->shared_state->disable_state) 512 wrmsrl(MSR_AMD64_LS_CFG, msr); 513 raw_spin_unlock(&st->shared_state->lock); 514 } 515 } 516 #else 517 static __always_inline void amd_set_core_ssb_state(unsigned long tifn) 518 { 519 u64 msr = x86_amd_ls_cfg_base | ssbd_tif_to_amd_ls_cfg(tifn); 520 521 wrmsrl(MSR_AMD64_LS_CFG, msr); 522 } 523 #endif 524 525 static __always_inline void amd_set_ssb_virt_state(unsigned long tifn) 526 { 527 /* 528 * SSBD has the same definition in SPEC_CTRL and VIRT_SPEC_CTRL, 529 * so ssbd_tif_to_spec_ctrl() just works. 530 */ 531 wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, ssbd_tif_to_spec_ctrl(tifn)); 532 } 533 534 /* 535 * Update the MSRs managing speculation control, during context switch. 536 * 537 * tifp: Previous task's thread flags 538 * tifn: Next task's thread flags 539 */ 540 static __always_inline void __speculation_ctrl_update(unsigned long tifp, 541 unsigned long tifn) 542 { 543 unsigned long tif_diff = tifp ^ tifn; 544 u64 msr = x86_spec_ctrl_base; 545 bool updmsr = false; 546 547 lockdep_assert_irqs_disabled(); 548 549 /* 550 * If TIF_SSBD is different, select the proper mitigation 551 * method. Note that if SSBD mitigation is disabled or permanentely 552 * enabled this branch can't be taken because nothing can set 553 * TIF_SSBD. 554 */ 555 if (tif_diff & _TIF_SSBD) { 556 if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) { 557 amd_set_ssb_virt_state(tifn); 558 } else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) { 559 amd_set_core_ssb_state(tifn); 560 } else if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) || 561 static_cpu_has(X86_FEATURE_AMD_SSBD)) { 562 msr |= ssbd_tif_to_spec_ctrl(tifn); 563 updmsr = true; 564 } 565 } 566 567 /* 568 * Only evaluate TIF_SPEC_IB if conditional STIBP is enabled, 569 * otherwise avoid the MSR write. 570 */ 571 if (IS_ENABLED(CONFIG_SMP) && 572 static_branch_unlikely(&switch_to_cond_stibp)) { 573 updmsr |= !!(tif_diff & _TIF_SPEC_IB); 574 msr |= stibp_tif_to_spec_ctrl(tifn); 575 } 576 577 if (updmsr) 578 wrmsrl(MSR_IA32_SPEC_CTRL, msr); 579 } 580 581 static unsigned long speculation_ctrl_update_tif(struct task_struct *tsk) 582 { 583 if (test_and_clear_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE)) { 584 if (task_spec_ssb_disable(tsk)) 585 set_tsk_thread_flag(tsk, TIF_SSBD); 586 else 587 clear_tsk_thread_flag(tsk, TIF_SSBD); 588 589 if (task_spec_ib_disable(tsk)) 590 set_tsk_thread_flag(tsk, TIF_SPEC_IB); 591 else 592 clear_tsk_thread_flag(tsk, TIF_SPEC_IB); 593 } 594 /* Return the updated threadinfo flags*/ 595 return task_thread_info(tsk)->flags; 596 } 597 598 void speculation_ctrl_update(unsigned long tif) 599 { 600 unsigned long flags; 601 602 /* Forced update. Make sure all relevant TIF flags are different */ 603 local_irq_save(flags); 604 __speculation_ctrl_update(~tif, tif); 605 local_irq_restore(flags); 606 } 607 608 /* Called from seccomp/prctl update */ 609 void speculation_ctrl_update_current(void) 610 { 611 preempt_disable(); 612 speculation_ctrl_update(speculation_ctrl_update_tif(current)); 613 preempt_enable(); 614 } 615 616 void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p) 617 { 618 unsigned long tifp, tifn; 619 620 tifn = READ_ONCE(task_thread_info(next_p)->flags); 621 tifp = READ_ONCE(task_thread_info(prev_p)->flags); 622 623 switch_to_bitmap(tifp); 624 625 propagate_user_return_notify(prev_p, next_p); 626 627 if ((tifp & _TIF_BLOCKSTEP || tifn & _TIF_BLOCKSTEP) && 628 arch_has_block_step()) { 629 unsigned long debugctl, msk; 630 631 rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); 632 debugctl &= ~DEBUGCTLMSR_BTF; 633 msk = tifn & _TIF_BLOCKSTEP; 634 debugctl |= (msk >> TIF_BLOCKSTEP) << DEBUGCTLMSR_BTF_SHIFT; 635 wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl); 636 } 637 638 if ((tifp ^ tifn) & _TIF_NOTSC) 639 cr4_toggle_bits_irqsoff(X86_CR4_TSD); 640 641 if ((tifp ^ tifn) & _TIF_NOCPUID) 642 set_cpuid_faulting(!!(tifn & _TIF_NOCPUID)); 643 644 if (likely(!((tifp | tifn) & _TIF_SPEC_FORCE_UPDATE))) { 645 __speculation_ctrl_update(tifp, tifn); 646 } else { 647 speculation_ctrl_update_tif(prev_p); 648 tifn = speculation_ctrl_update_tif(next_p); 649 650 /* Enforce MSR update to ensure consistent state */ 651 __speculation_ctrl_update(~tifn, tifn); 652 } 653 } 654 655 /* 656 * Idle related variables and functions 657 */ 658 unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; 659 EXPORT_SYMBOL(boot_option_idle_override); 660 661 static void (*x86_idle)(void); 662 663 #ifndef CONFIG_SMP 664 static inline void play_dead(void) 665 { 666 BUG(); 667 } 668 #endif 669 670 void arch_cpu_idle_enter(void) 671 { 672 tsc_verify_tsc_adjust(false); 673 local_touch_nmi(); 674 } 675 676 void arch_cpu_idle_dead(void) 677 { 678 play_dead(); 679 } 680 681 /* 682 * Called from the generic idle code. 683 */ 684 void arch_cpu_idle(void) 685 { 686 x86_idle(); 687 } 688 689 /* 690 * We use this if we don't have any better idle routine.. 691 */ 692 void __cpuidle default_idle(void) 693 { 694 trace_cpu_idle_rcuidle(1, smp_processor_id()); 695 safe_halt(); 696 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); 697 } 698 #if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE) 699 EXPORT_SYMBOL(default_idle); 700 #endif 701 702 #ifdef CONFIG_XEN 703 bool xen_set_default_idle(void) 704 { 705 bool ret = !!x86_idle; 706 707 x86_idle = default_idle; 708 709 return ret; 710 } 711 #endif 712 713 void stop_this_cpu(void *dummy) 714 { 715 local_irq_disable(); 716 /* 717 * Remove this CPU: 718 */ 719 set_cpu_online(smp_processor_id(), false); 720 disable_local_APIC(); 721 mcheck_cpu_clear(this_cpu_ptr(&cpu_info)); 722 723 /* 724 * Use wbinvd on processors that support SME. This provides support 725 * for performing a successful kexec when going from SME inactive 726 * to SME active (or vice-versa). The cache must be cleared so that 727 * if there are entries with the same physical address, both with and 728 * without the encryption bit, they don't race each other when flushed 729 * and potentially end up with the wrong entry being committed to 730 * memory. 731 */ 732 if (boot_cpu_has(X86_FEATURE_SME)) 733 native_wbinvd(); 734 for (;;) { 735 /* 736 * Use native_halt() so that memory contents don't change 737 * (stack usage and variables) after possibly issuing the 738 * native_wbinvd() above. 739 */ 740 native_halt(); 741 } 742 } 743 744 /* 745 * AMD Erratum 400 aware idle routine. We handle it the same way as C3 power 746 * states (local apic timer and TSC stop). 747 */ 748 static void amd_e400_idle(void) 749 { 750 /* 751 * We cannot use static_cpu_has_bug() here because X86_BUG_AMD_APIC_C1E 752 * gets set after static_cpu_has() places have been converted via 753 * alternatives. 754 */ 755 if (!boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) { 756 default_idle(); 757 return; 758 } 759 760 tick_broadcast_enter(); 761 762 default_idle(); 763 764 /* 765 * The switch back from broadcast mode needs to be called with 766 * interrupts disabled. 767 */ 768 local_irq_disable(); 769 tick_broadcast_exit(); 770 local_irq_enable(); 771 } 772 773 /* 774 * Intel Core2 and older machines prefer MWAIT over HALT for C1. 775 * We can't rely on cpuidle installing MWAIT, because it will not load 776 * on systems that support only C1 -- so the boot default must be MWAIT. 777 * 778 * Some AMD machines are the opposite, they depend on using HALT. 779 * 780 * So for default C1, which is used during boot until cpuidle loads, 781 * use MWAIT-C1 on Intel HW that has it, else use HALT. 782 */ 783 static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c) 784 { 785 if (c->x86_vendor != X86_VENDOR_INTEL) 786 return 0; 787 788 if (!cpu_has(c, X86_FEATURE_MWAIT) || boot_cpu_has_bug(X86_BUG_MONITOR)) 789 return 0; 790 791 return 1; 792 } 793 794 /* 795 * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT 796 * with interrupts enabled and no flags, which is backwards compatible with the 797 * original MWAIT implementation. 798 */ 799 static __cpuidle void mwait_idle(void) 800 { 801 if (!current_set_polling_and_test()) { 802 trace_cpu_idle_rcuidle(1, smp_processor_id()); 803 if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { 804 mb(); /* quirk */ 805 clflush((void *)¤t_thread_info()->flags); 806 mb(); /* quirk */ 807 } 808 809 __monitor((void *)¤t_thread_info()->flags, 0, 0); 810 if (!need_resched()) 811 __sti_mwait(0, 0); 812 else 813 local_irq_enable(); 814 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); 815 } else { 816 local_irq_enable(); 817 } 818 __current_clr_polling(); 819 } 820 821 void select_idle_routine(const struct cpuinfo_x86 *c) 822 { 823 #ifdef CONFIG_SMP 824 if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1) 825 pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n"); 826 #endif 827 if (x86_idle || boot_option_idle_override == IDLE_POLL) 828 return; 829 830 if (boot_cpu_has_bug(X86_BUG_AMD_E400)) { 831 pr_info("using AMD E400 aware idle routine\n"); 832 x86_idle = amd_e400_idle; 833 } else if (prefer_mwait_c1_over_halt(c)) { 834 pr_info("using mwait in idle threads\n"); 835 x86_idle = mwait_idle; 836 } else 837 x86_idle = default_idle; 838 } 839 840 void amd_e400_c1e_apic_setup(void) 841 { 842 if (boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) { 843 pr_info("Switch to broadcast mode on CPU%d\n", smp_processor_id()); 844 local_irq_disable(); 845 tick_broadcast_force(); 846 local_irq_enable(); 847 } 848 } 849 850 void __init arch_post_acpi_subsys_init(void) 851 { 852 u32 lo, hi; 853 854 if (!boot_cpu_has_bug(X86_BUG_AMD_E400)) 855 return; 856 857 /* 858 * AMD E400 detection needs to happen after ACPI has been enabled. If 859 * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in 860 * MSR_K8_INT_PENDING_MSG. 861 */ 862 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); 863 if (!(lo & K8_INTP_C1E_ACTIVE_MASK)) 864 return; 865 866 boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E); 867 868 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) 869 mark_tsc_unstable("TSC halt in AMD C1E"); 870 pr_info("System has AMD C1E enabled\n"); 871 } 872 873 static int __init idle_setup(char *str) 874 { 875 if (!str) 876 return -EINVAL; 877 878 if (!strcmp(str, "poll")) { 879 pr_info("using polling idle threads\n"); 880 boot_option_idle_override = IDLE_POLL; 881 cpu_idle_poll_ctrl(true); 882 } else if (!strcmp(str, "halt")) { 883 /* 884 * When the boot option of idle=halt is added, halt is 885 * forced to be used for CPU idle. In such case CPU C2/C3 886 * won't be used again. 887 * To continue to load the CPU idle driver, don't touch 888 * the boot_option_idle_override. 889 */ 890 x86_idle = default_idle; 891 boot_option_idle_override = IDLE_HALT; 892 } else if (!strcmp(str, "nomwait")) { 893 /* 894 * If the boot option of "idle=nomwait" is added, 895 * it means that mwait will be disabled for CPU C2/C3 896 * states. In such case it won't touch the variable 897 * of boot_option_idle_override. 898 */ 899 boot_option_idle_override = IDLE_NOMWAIT; 900 } else 901 return -1; 902 903 return 0; 904 } 905 early_param("idle", idle_setup); 906 907 unsigned long arch_align_stack(unsigned long sp) 908 { 909 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) 910 sp -= get_random_int() % 8192; 911 return sp & ~0xf; 912 } 913 914 unsigned long arch_randomize_brk(struct mm_struct *mm) 915 { 916 return randomize_page(mm->brk, 0x02000000); 917 } 918 919 /* 920 * Called from fs/proc with a reference on @p to find the function 921 * which called into schedule(). This needs to be done carefully 922 * because the task might wake up and we might look at a stack 923 * changing under us. 924 */ 925 unsigned long get_wchan(struct task_struct *p) 926 { 927 unsigned long start, bottom, top, sp, fp, ip, ret = 0; 928 int count = 0; 929 930 if (p == current || p->state == TASK_RUNNING) 931 return 0; 932 933 if (!try_get_task_stack(p)) 934 return 0; 935 936 start = (unsigned long)task_stack_page(p); 937 if (!start) 938 goto out; 939 940 /* 941 * Layout of the stack page: 942 * 943 * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long) 944 * PADDING 945 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING 946 * stack 947 * ----------- bottom = start 948 * 949 * The tasks stack pointer points at the location where the 950 * framepointer is stored. The data on the stack is: 951 * ... IP FP ... IP FP 952 * 953 * We need to read FP and IP, so we need to adjust the upper 954 * bound by another unsigned long. 955 */ 956 top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING; 957 top -= 2 * sizeof(unsigned long); 958 bottom = start; 959 960 sp = READ_ONCE(p->thread.sp); 961 if (sp < bottom || sp > top) 962 goto out; 963 964 fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp); 965 do { 966 if (fp < bottom || fp > top) 967 goto out; 968 ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long))); 969 if (!in_sched_functions(ip)) { 970 ret = ip; 971 goto out; 972 } 973 fp = READ_ONCE_NOCHECK(*(unsigned long *)fp); 974 } while (count++ < 16 && p->state != TASK_RUNNING); 975 976 out: 977 put_task_stack(p); 978 return ret; 979 } 980 981 long do_arch_prctl_common(struct task_struct *task, int option, 982 unsigned long cpuid_enabled) 983 { 984 switch (option) { 985 case ARCH_GET_CPUID: 986 return get_cpuid_mode(); 987 case ARCH_SET_CPUID: 988 return set_cpuid_mode(task, cpuid_enabled); 989 } 990 991 return -EINVAL; 992 } 993