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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 <linux/uaccess.h>
32#include <asm/mwait.h>
33#include <asm/fpu/api.h>
34#include <asm/fpu/sched.h>
35#include <asm/fpu/xstate.h>
36#include <asm/debugreg.h>
37#include <asm/nmi.h>
38#include <asm/tlbflush.h>
39#include <asm/mce.h>
40#include <asm/vm86.h>
41#include <asm/switch_to.h>
42#include <asm/desc.h>
43#include <asm/prctl.h>
44#include <asm/spec-ctrl.h>
45#include <asm/io_bitmap.h>
46#include <asm/proto.h>
47#include <asm/frame.h>
48#include <asm/unwind.h>
49#include <asm/tdx.h>
50
51#include "process.h"
52
53/*
54 * per-CPU TSS segments. Threads are completely 'soft' on Linux,
55 * no more per-task TSS's. The TSS size is kept cacheline-aligned
56 * so they are allowed to end up in the .data..cacheline_aligned
57 * section. Since TSS's are completely CPU-local, we want them
58 * on exact cacheline boundaries, to eliminate cacheline ping-pong.
59 */
60__visible DEFINE_PER_CPU_PAGE_ALIGNED(struct tss_struct, cpu_tss_rw) = {
61 .x86_tss = {
62 /*
63 * .sp0 is only used when entering ring 0 from a lower
64 * privilege level. Since the init task never runs anything
65 * but ring 0 code, there is no need for a valid value here.
66 * Poison it.
67 */
68 .sp0 = (1UL << (BITS_PER_LONG-1)) + 1,
69
70#ifdef CONFIG_X86_32
71 .sp1 = TOP_OF_INIT_STACK,
72
73 .ss0 = __KERNEL_DS,
74 .ss1 = __KERNEL_CS,
75#endif
76 .io_bitmap_base = IO_BITMAP_OFFSET_INVALID,
77 },
78};
79EXPORT_PER_CPU_SYMBOL(cpu_tss_rw);
80
81DEFINE_PER_CPU(bool, __tss_limit_invalid);
82EXPORT_PER_CPU_SYMBOL_GPL(__tss_limit_invalid);
83
84/*
85 * this gets called so that we can store lazy state into memory and copy the
86 * current task into the new thread.
87 */
88int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
89{
90 memcpy(dst, src, arch_task_struct_size);
91#ifdef CONFIG_VM86
92 dst->thread.vm86 = NULL;
93#endif
94 /* Drop the copied pointer to current's fpstate */
95 dst->thread.fpu.fpstate = NULL;
96
97 return 0;
98}
99
100#ifdef CONFIG_X86_64
101void arch_release_task_struct(struct task_struct *tsk)
102{
103 if (fpu_state_size_dynamic())
104 fpstate_free(&tsk->thread.fpu);
105}
106#endif
107
108/*
109 * Free thread data structures etc..
110 */
111void exit_thread(struct task_struct *tsk)
112{
113 struct thread_struct *t = &tsk->thread;
114 struct fpu *fpu = &t->fpu;
115
116 if (test_thread_flag(TIF_IO_BITMAP))
117 io_bitmap_exit(tsk);
118
119 free_vm86(t);
120
121 fpu__drop(fpu);
122}
123
124static int set_new_tls(struct task_struct *p, unsigned long tls)
125{
126 struct user_desc __user *utls = (struct user_desc __user *)tls;
127
128 if (in_ia32_syscall())
129 return do_set_thread_area(p, -1, utls, 0);
130 else
131 return do_set_thread_area_64(p, ARCH_SET_FS, tls);
132}
133
134int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
135{
136 unsigned long clone_flags = args->flags;
137 unsigned long sp = args->stack;
138 unsigned long tls = args->tls;
139 struct inactive_task_frame *frame;
140 struct fork_frame *fork_frame;
141 struct pt_regs *childregs;
142 int ret = 0;
143
144 childregs = task_pt_regs(p);
145 fork_frame = container_of(childregs, struct fork_frame, regs);
146 frame = &fork_frame->frame;
147
148 frame->bp = encode_frame_pointer(childregs);
149 frame->ret_addr = (unsigned long) ret_from_fork;
150 p->thread.sp = (unsigned long) fork_frame;
151 p->thread.io_bitmap = NULL;
152 p->thread.iopl_warn = 0;
153 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
154
155#ifdef CONFIG_X86_64
156 current_save_fsgs();
157 p->thread.fsindex = current->thread.fsindex;
158 p->thread.fsbase = current->thread.fsbase;
159 p->thread.gsindex = current->thread.gsindex;
160 p->thread.gsbase = current->thread.gsbase;
161
162 savesegment(es, p->thread.es);
163 savesegment(ds, p->thread.ds);
164#else
165 p->thread.sp0 = (unsigned long) (childregs + 1);
166 savesegment(gs, p->thread.gs);
167 /*
168 * Clear all status flags including IF and set fixed bit. 64bit
169 * does not have this initialization as the frame does not contain
170 * flags. The flags consistency (especially vs. AC) is there
171 * ensured via objtool, which lacks 32bit support.
172 */
173 frame->flags = X86_EFLAGS_FIXED;
174#endif
175
176 fpu_clone(p, clone_flags, args->fn);
177
178 /* Kernel thread ? */
179 if (unlikely(p->flags & PF_KTHREAD)) {
180 p->thread.pkru = pkru_get_init_value();
181 memset(childregs, 0, sizeof(struct pt_regs));
182 kthread_frame_init(frame, args->fn, args->fn_arg);
183 return 0;
184 }
185
186 /*
187 * Clone current's PKRU value from hardware. tsk->thread.pkru
188 * is only valid when scheduled out.
189 */
190 p->thread.pkru = read_pkru();
191
192 frame->bx = 0;
193 *childregs = *current_pt_regs();
194 childregs->ax = 0;
195 if (sp)
196 childregs->sp = sp;
197
198 if (unlikely(args->fn)) {
199 /*
200 * A user space thread, but it doesn't return to
201 * ret_after_fork().
202 *
203 * In order to indicate that to tools like gdb,
204 * we reset the stack and instruction pointers.
205 *
206 * It does the same kernel frame setup to return to a kernel
207 * function that a kernel thread does.
208 */
209 childregs->sp = 0;
210 childregs->ip = 0;
211 kthread_frame_init(frame, args->fn, args->fn_arg);
212 return 0;
213 }
214
215 /* Set a new TLS for the child thread? */
216 if (clone_flags & CLONE_SETTLS)
217 ret = set_new_tls(p, tls);
218
219 if (!ret && unlikely(test_tsk_thread_flag(current, TIF_IO_BITMAP)))
220 io_bitmap_share(p);
221
222 return ret;
223}
224
225static void pkru_flush_thread(void)
226{
227 /*
228 * If PKRU is enabled the default PKRU value has to be loaded into
229 * the hardware right here (similar to context switch).
230 */
231 pkru_write_default();
232}
233
234void flush_thread(void)
235{
236 struct task_struct *tsk = current;
237
238 flush_ptrace_hw_breakpoint(tsk);
239 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
240
241 fpu_flush_thread();
242 pkru_flush_thread();
243}
244
245void disable_TSC(void)
246{
247 preempt_disable();
248 if (!test_and_set_thread_flag(TIF_NOTSC))
249 /*
250 * Must flip the CPU state synchronously with
251 * TIF_NOTSC in the current running context.
252 */
253 cr4_set_bits(X86_CR4_TSD);
254 preempt_enable();
255}
256
257static void enable_TSC(void)
258{
259 preempt_disable();
260 if (test_and_clear_thread_flag(TIF_NOTSC))
261 /*
262 * Must flip the CPU state synchronously with
263 * TIF_NOTSC in the current running context.
264 */
265 cr4_clear_bits(X86_CR4_TSD);
266 preempt_enable();
267}
268
269int get_tsc_mode(unsigned long adr)
270{
271 unsigned int val;
272
273 if (test_thread_flag(TIF_NOTSC))
274 val = PR_TSC_SIGSEGV;
275 else
276 val = PR_TSC_ENABLE;
277
278 return put_user(val, (unsigned int __user *)adr);
279}
280
281int set_tsc_mode(unsigned int val)
282{
283 if (val == PR_TSC_SIGSEGV)
284 disable_TSC();
285 else if (val == PR_TSC_ENABLE)
286 enable_TSC();
287 else
288 return -EINVAL;
289
290 return 0;
291}
292
293DEFINE_PER_CPU(u64, msr_misc_features_shadow);
294
295static void set_cpuid_faulting(bool on)
296{
297 u64 msrval;
298
299 msrval = this_cpu_read(msr_misc_features_shadow);
300 msrval &= ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT;
301 msrval |= (on << MSR_MISC_FEATURES_ENABLES_CPUID_FAULT_BIT);
302 this_cpu_write(msr_misc_features_shadow, msrval);
303 wrmsrl(MSR_MISC_FEATURES_ENABLES, msrval);
304}
305
306static void disable_cpuid(void)
307{
308 preempt_disable();
309 if (!test_and_set_thread_flag(TIF_NOCPUID)) {
310 /*
311 * Must flip the CPU state synchronously with
312 * TIF_NOCPUID in the current running context.
313 */
314 set_cpuid_faulting(true);
315 }
316 preempt_enable();
317}
318
319static void enable_cpuid(void)
320{
321 preempt_disable();
322 if (test_and_clear_thread_flag(TIF_NOCPUID)) {
323 /*
324 * Must flip the CPU state synchronously with
325 * TIF_NOCPUID in the current running context.
326 */
327 set_cpuid_faulting(false);
328 }
329 preempt_enable();
330}
331
332static int get_cpuid_mode(void)
333{
334 return !test_thread_flag(TIF_NOCPUID);
335}
336
337static int set_cpuid_mode(unsigned long cpuid_enabled)
338{
339 if (!boot_cpu_has(X86_FEATURE_CPUID_FAULT))
340 return -ENODEV;
341
342 if (cpuid_enabled)
343 enable_cpuid();
344 else
345 disable_cpuid();
346
347 return 0;
348}
349
350/*
351 * Called immediately after a successful exec.
352 */
353void arch_setup_new_exec(void)
354{
355 /* If cpuid was previously disabled for this task, re-enable it. */
356 if (test_thread_flag(TIF_NOCPUID))
357 enable_cpuid();
358
359 /*
360 * Don't inherit TIF_SSBD across exec boundary when
361 * PR_SPEC_DISABLE_NOEXEC is used.
362 */
363 if (test_thread_flag(TIF_SSBD) &&
364 task_spec_ssb_noexec(current)) {
365 clear_thread_flag(TIF_SSBD);
366 task_clear_spec_ssb_disable(current);
367 task_clear_spec_ssb_noexec(current);
368 speculation_ctrl_update(read_thread_flags());
369 }
370}
371
372#ifdef CONFIG_X86_IOPL_IOPERM
373static inline void switch_to_bitmap(unsigned long tifp)
374{
375 /*
376 * Invalidate I/O bitmap if the previous task used it. This prevents
377 * any possible leakage of an active I/O bitmap.
378 *
379 * If the next task has an I/O bitmap it will handle it on exit to
380 * user mode.
381 */
382 if (tifp & _TIF_IO_BITMAP)
383 tss_invalidate_io_bitmap();
384}
385
386static void tss_copy_io_bitmap(struct tss_struct *tss, struct io_bitmap *iobm)
387{
388 /*
389 * Copy at least the byte range of the incoming tasks bitmap which
390 * covers the permitted I/O ports.
391 *
392 * If the previous task which used an I/O bitmap had more bits
393 * permitted, then the copy needs to cover those as well so they
394 * get turned off.
395 */
396 memcpy(tss->io_bitmap.bitmap, iobm->bitmap,
397 max(tss->io_bitmap.prev_max, iobm->max));
398
399 /*
400 * Store the new max and the sequence number of this bitmap
401 * and a pointer to the bitmap itself.
402 */
403 tss->io_bitmap.prev_max = iobm->max;
404 tss->io_bitmap.prev_sequence = iobm->sequence;
405}
406
407/**
408 * native_tss_update_io_bitmap - Update I/O bitmap before exiting to user mode
409 */
410void native_tss_update_io_bitmap(void)
411{
412 struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw);
413 struct thread_struct *t = ¤t->thread;
414 u16 *base = &tss->x86_tss.io_bitmap_base;
415
416 if (!test_thread_flag(TIF_IO_BITMAP)) {
417 native_tss_invalidate_io_bitmap();
418 return;
419 }
420
421 if (IS_ENABLED(CONFIG_X86_IOPL_IOPERM) && t->iopl_emul == 3) {
422 *base = IO_BITMAP_OFFSET_VALID_ALL;
423 } else {
424 struct io_bitmap *iobm = t->io_bitmap;
425
426 /*
427 * Only copy bitmap data when the sequence number differs. The
428 * update time is accounted to the incoming task.
429 */
430 if (tss->io_bitmap.prev_sequence != iobm->sequence)
431 tss_copy_io_bitmap(tss, iobm);
432
433 /* Enable the bitmap */
434 *base = IO_BITMAP_OFFSET_VALID_MAP;
435 }
436
437 /*
438 * Make sure that the TSS limit is covering the IO bitmap. It might have
439 * been cut down by a VMEXIT to 0x67 which would cause a subsequent I/O
440 * access from user space to trigger a #GP because tbe bitmap is outside
441 * the TSS limit.
442 */
443 refresh_tss_limit();
444}
445#else /* CONFIG_X86_IOPL_IOPERM */
446static inline void switch_to_bitmap(unsigned long tifp) { }
447#endif
448
449#ifdef CONFIG_SMP
450
451struct ssb_state {
452 struct ssb_state *shared_state;
453 raw_spinlock_t lock;
454 unsigned int disable_state;
455 unsigned long local_state;
456};
457
458#define LSTATE_SSB 0
459
460static DEFINE_PER_CPU(struct ssb_state, ssb_state);
461
462void speculative_store_bypass_ht_init(void)
463{
464 struct ssb_state *st = this_cpu_ptr(&ssb_state);
465 unsigned int this_cpu = smp_processor_id();
466 unsigned int cpu;
467
468 st->local_state = 0;
469
470 /*
471 * Shared state setup happens once on the first bringup
472 * of the CPU. It's not destroyed on CPU hotunplug.
473 */
474 if (st->shared_state)
475 return;
476
477 raw_spin_lock_init(&st->lock);
478
479 /*
480 * Go over HT siblings and check whether one of them has set up the
481 * shared state pointer already.
482 */
483 for_each_cpu(cpu, topology_sibling_cpumask(this_cpu)) {
484 if (cpu == this_cpu)
485 continue;
486
487 if (!per_cpu(ssb_state, cpu).shared_state)
488 continue;
489
490 /* Link it to the state of the sibling: */
491 st->shared_state = per_cpu(ssb_state, cpu).shared_state;
492 return;
493 }
494
495 /*
496 * First HT sibling to come up on the core. Link shared state of
497 * the first HT sibling to itself. The siblings on the same core
498 * which come up later will see the shared state pointer and link
499 * themselves to the state of this CPU.
500 */
501 st->shared_state = st;
502}
503
504/*
505 * Logic is: First HT sibling enables SSBD for both siblings in the core
506 * and last sibling to disable it, disables it for the whole core. This how
507 * MSR_SPEC_CTRL works in "hardware":
508 *
509 * CORE_SPEC_CTRL = THREAD0_SPEC_CTRL | THREAD1_SPEC_CTRL
510 */
511static __always_inline void amd_set_core_ssb_state(unsigned long tifn)
512{
513 struct ssb_state *st = this_cpu_ptr(&ssb_state);
514 u64 msr = x86_amd_ls_cfg_base;
515
516 if (!static_cpu_has(X86_FEATURE_ZEN)) {
517 msr |= ssbd_tif_to_amd_ls_cfg(tifn);
518 wrmsrl(MSR_AMD64_LS_CFG, msr);
519 return;
520 }
521
522 if (tifn & _TIF_SSBD) {
523 /*
524 * Since this can race with prctl(), block reentry on the
525 * same CPU.
526 */
527 if (__test_and_set_bit(LSTATE_SSB, &st->local_state))
528 return;
529
530 msr |= x86_amd_ls_cfg_ssbd_mask;
531
532 raw_spin_lock(&st->shared_state->lock);
533 /* First sibling enables SSBD: */
534 if (!st->shared_state->disable_state)
535 wrmsrl(MSR_AMD64_LS_CFG, msr);
536 st->shared_state->disable_state++;
537 raw_spin_unlock(&st->shared_state->lock);
538 } else {
539 if (!__test_and_clear_bit(LSTATE_SSB, &st->local_state))
540 return;
541
542 raw_spin_lock(&st->shared_state->lock);
543 st->shared_state->disable_state--;
544 if (!st->shared_state->disable_state)
545 wrmsrl(MSR_AMD64_LS_CFG, msr);
546 raw_spin_unlock(&st->shared_state->lock);
547 }
548}
549#else
550static __always_inline void amd_set_core_ssb_state(unsigned long tifn)
551{
552 u64 msr = x86_amd_ls_cfg_base | ssbd_tif_to_amd_ls_cfg(tifn);
553
554 wrmsrl(MSR_AMD64_LS_CFG, msr);
555}
556#endif
557
558static __always_inline void amd_set_ssb_virt_state(unsigned long tifn)
559{
560 /*
561 * SSBD has the same definition in SPEC_CTRL and VIRT_SPEC_CTRL,
562 * so ssbd_tif_to_spec_ctrl() just works.
563 */
564 wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, ssbd_tif_to_spec_ctrl(tifn));
565}
566
567/*
568 * Update the MSRs managing speculation control, during context switch.
569 *
570 * tifp: Previous task's thread flags
571 * tifn: Next task's thread flags
572 */
573static __always_inline void __speculation_ctrl_update(unsigned long tifp,
574 unsigned long tifn)
575{
576 unsigned long tif_diff = tifp ^ tifn;
577 u64 msr = x86_spec_ctrl_base;
578 bool updmsr = false;
579
580 lockdep_assert_irqs_disabled();
581
582 /* Handle change of TIF_SSBD depending on the mitigation method. */
583 if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) {
584 if (tif_diff & _TIF_SSBD)
585 amd_set_ssb_virt_state(tifn);
586 } else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) {
587 if (tif_diff & _TIF_SSBD)
588 amd_set_core_ssb_state(tifn);
589 } else if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
590 static_cpu_has(X86_FEATURE_AMD_SSBD)) {
591 updmsr |= !!(tif_diff & _TIF_SSBD);
592 msr |= ssbd_tif_to_spec_ctrl(tifn);
593 }
594
595 /* Only evaluate TIF_SPEC_IB if conditional STIBP is enabled. */
596 if (IS_ENABLED(CONFIG_SMP) &&
597 static_branch_unlikely(&switch_to_cond_stibp)) {
598 updmsr |= !!(tif_diff & _TIF_SPEC_IB);
599 msr |= stibp_tif_to_spec_ctrl(tifn);
600 }
601
602 if (updmsr)
603 update_spec_ctrl_cond(msr);
604}
605
606static unsigned long speculation_ctrl_update_tif(struct task_struct *tsk)
607{
608 if (test_and_clear_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE)) {
609 if (task_spec_ssb_disable(tsk))
610 set_tsk_thread_flag(tsk, TIF_SSBD);
611 else
612 clear_tsk_thread_flag(tsk, TIF_SSBD);
613
614 if (task_spec_ib_disable(tsk))
615 set_tsk_thread_flag(tsk, TIF_SPEC_IB);
616 else
617 clear_tsk_thread_flag(tsk, TIF_SPEC_IB);
618 }
619 /* Return the updated threadinfo flags*/
620 return read_task_thread_flags(tsk);
621}
622
623void speculation_ctrl_update(unsigned long tif)
624{
625 unsigned long flags;
626
627 /* Forced update. Make sure all relevant TIF flags are different */
628 local_irq_save(flags);
629 __speculation_ctrl_update(~tif, tif);
630 local_irq_restore(flags);
631}
632
633/* Called from seccomp/prctl update */
634void speculation_ctrl_update_current(void)
635{
636 preempt_disable();
637 speculation_ctrl_update(speculation_ctrl_update_tif(current));
638 preempt_enable();
639}
640
641static inline void cr4_toggle_bits_irqsoff(unsigned long mask)
642{
643 unsigned long newval, cr4 = this_cpu_read(cpu_tlbstate.cr4);
644
645 newval = cr4 ^ mask;
646 if (newval != cr4) {
647 this_cpu_write(cpu_tlbstate.cr4, newval);
648 __write_cr4(newval);
649 }
650}
651
652void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
653{
654 unsigned long tifp, tifn;
655
656 tifn = read_task_thread_flags(next_p);
657 tifp = read_task_thread_flags(prev_p);
658
659 switch_to_bitmap(tifp);
660
661 propagate_user_return_notify(prev_p, next_p);
662
663 if ((tifp & _TIF_BLOCKSTEP || tifn & _TIF_BLOCKSTEP) &&
664 arch_has_block_step()) {
665 unsigned long debugctl, msk;
666
667 rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
668 debugctl &= ~DEBUGCTLMSR_BTF;
669 msk = tifn & _TIF_BLOCKSTEP;
670 debugctl |= (msk >> TIF_BLOCKSTEP) << DEBUGCTLMSR_BTF_SHIFT;
671 wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
672 }
673
674 if ((tifp ^ tifn) & _TIF_NOTSC)
675 cr4_toggle_bits_irqsoff(X86_CR4_TSD);
676
677 if ((tifp ^ tifn) & _TIF_NOCPUID)
678 set_cpuid_faulting(!!(tifn & _TIF_NOCPUID));
679
680 if (likely(!((tifp | tifn) & _TIF_SPEC_FORCE_UPDATE))) {
681 __speculation_ctrl_update(tifp, tifn);
682 } else {
683 speculation_ctrl_update_tif(prev_p);
684 tifn = speculation_ctrl_update_tif(next_p);
685
686 /* Enforce MSR update to ensure consistent state */
687 __speculation_ctrl_update(~tifn, tifn);
688 }
689}
690
691/*
692 * Idle related variables and functions
693 */
694unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
695EXPORT_SYMBOL(boot_option_idle_override);
696
697static void (*x86_idle)(void);
698
699#ifndef CONFIG_SMP
700static inline void play_dead(void)
701{
702 BUG();
703}
704#endif
705
706void arch_cpu_idle_enter(void)
707{
708 tsc_verify_tsc_adjust(false);
709 local_touch_nmi();
710}
711
712void arch_cpu_idle_dead(void)
713{
714 play_dead();
715}
716
717/*
718 * Called from the generic idle code.
719 */
720void arch_cpu_idle(void)
721{
722 x86_idle();
723}
724
725/*
726 * We use this if we don't have any better idle routine..
727 */
728void __cpuidle default_idle(void)
729{
730 raw_safe_halt();
731}
732#if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE)
733EXPORT_SYMBOL(default_idle);
734#endif
735
736#ifdef CONFIG_XEN
737bool xen_set_default_idle(void)
738{
739 bool ret = !!x86_idle;
740
741 x86_idle = default_idle;
742
743 return ret;
744}
745#endif
746
747void __noreturn stop_this_cpu(void *dummy)
748{
749 local_irq_disable();
750 /*
751 * Remove this CPU:
752 */
753 set_cpu_online(smp_processor_id(), false);
754 disable_local_APIC();
755 mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
756
757 /*
758 * Use wbinvd on processors that support SME. This provides support
759 * for performing a successful kexec when going from SME inactive
760 * to SME active (or vice-versa). The cache must be cleared so that
761 * if there are entries with the same physical address, both with and
762 * without the encryption bit, they don't race each other when flushed
763 * and potentially end up with the wrong entry being committed to
764 * memory.
765 *
766 * Test the CPUID bit directly because the machine might've cleared
767 * X86_FEATURE_SME due to cmdline options.
768 */
769 if (cpuid_eax(0x8000001f) & BIT(0))
770 native_wbinvd();
771 for (;;) {
772 /*
773 * Use native_halt() so that memory contents don't change
774 * (stack usage and variables) after possibly issuing the
775 * native_wbinvd() above.
776 */
777 native_halt();
778 }
779}
780
781/*
782 * AMD Erratum 400 aware idle routine. We handle it the same way as C3 power
783 * states (local apic timer and TSC stop).
784 *
785 * XXX this function is completely buggered vs RCU and tracing.
786 */
787static void amd_e400_idle(void)
788{
789 /*
790 * We cannot use static_cpu_has_bug() here because X86_BUG_AMD_APIC_C1E
791 * gets set after static_cpu_has() places have been converted via
792 * alternatives.
793 */
794 if (!boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) {
795 default_idle();
796 return;
797 }
798
799 tick_broadcast_enter();
800
801 default_idle();
802
803 /*
804 * The switch back from broadcast mode needs to be called with
805 * interrupts disabled.
806 */
807 raw_local_irq_disable();
808 tick_broadcast_exit();
809 raw_local_irq_enable();
810}
811
812/*
813 * Prefer MWAIT over HALT if MWAIT is supported, MWAIT_CPUID leaf
814 * exists and whenever MONITOR/MWAIT extensions are present there is at
815 * least one C1 substate.
816 *
817 * Do not prefer MWAIT if MONITOR instruction has a bug or idle=nomwait
818 * is passed to kernel commandline parameter.
819 */
820static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
821{
822 u32 eax, ebx, ecx, edx;
823
824 /* User has disallowed the use of MWAIT. Fallback to HALT */
825 if (boot_option_idle_override == IDLE_NOMWAIT)
826 return 0;
827
828 /* MWAIT is not supported on this platform. Fallback to HALT */
829 if (!cpu_has(c, X86_FEATURE_MWAIT))
830 return 0;
831
832 /* Monitor has a bug. Fallback to HALT */
833 if (boot_cpu_has_bug(X86_BUG_MONITOR))
834 return 0;
835
836 cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
837
838 /*
839 * If MWAIT extensions are not available, it is safe to use MWAIT
840 * with EAX=0, ECX=0.
841 */
842 if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED))
843 return 1;
844
845 /*
846 * If MWAIT extensions are available, there should be at least one
847 * MWAIT C1 substate present.
848 */
849 return (edx & MWAIT_C1_SUBSTATE_MASK);
850}
851
852/*
853 * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT
854 * with interrupts enabled and no flags, which is backwards compatible with the
855 * original MWAIT implementation.
856 */
857static __cpuidle void mwait_idle(void)
858{
859 if (!current_set_polling_and_test()) {
860 if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
861 mb(); /* quirk */
862 clflush((void *)¤t_thread_info()->flags);
863 mb(); /* quirk */
864 }
865
866 __monitor((void *)¤t_thread_info()->flags, 0, 0);
867 if (!need_resched())
868 __sti_mwait(0, 0);
869 else
870 raw_local_irq_enable();
871 } else {
872 raw_local_irq_enable();
873 }
874 __current_clr_polling();
875}
876
877void select_idle_routine(const struct cpuinfo_x86 *c)
878{
879#ifdef CONFIG_SMP
880 if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
881 pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
882#endif
883 if (x86_idle || boot_option_idle_override == IDLE_POLL)
884 return;
885
886 if (boot_cpu_has_bug(X86_BUG_AMD_E400)) {
887 pr_info("using AMD E400 aware idle routine\n");
888 x86_idle = amd_e400_idle;
889 } else if (prefer_mwait_c1_over_halt(c)) {
890 pr_info("using mwait in idle threads\n");
891 x86_idle = mwait_idle;
892 } else if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
893 pr_info("using TDX aware idle routine\n");
894 x86_idle = tdx_safe_halt;
895 } else
896 x86_idle = default_idle;
897}
898
899void amd_e400_c1e_apic_setup(void)
900{
901 if (boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) {
902 pr_info("Switch to broadcast mode on CPU%d\n", smp_processor_id());
903 local_irq_disable();
904 tick_broadcast_force();
905 local_irq_enable();
906 }
907}
908
909void __init arch_post_acpi_subsys_init(void)
910{
911 u32 lo, hi;
912
913 if (!boot_cpu_has_bug(X86_BUG_AMD_E400))
914 return;
915
916 /*
917 * AMD E400 detection needs to happen after ACPI has been enabled. If
918 * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in
919 * MSR_K8_INT_PENDING_MSG.
920 */
921 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
922 if (!(lo & K8_INTP_C1E_ACTIVE_MASK))
923 return;
924
925 boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E);
926
927 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
928 mark_tsc_unstable("TSC halt in AMD C1E");
929 pr_info("System has AMD C1E enabled\n");
930}
931
932static int __init idle_setup(char *str)
933{
934 if (!str)
935 return -EINVAL;
936
937 if (!strcmp(str, "poll")) {
938 pr_info("using polling idle threads\n");
939 boot_option_idle_override = IDLE_POLL;
940 cpu_idle_poll_ctrl(true);
941 } else if (!strcmp(str, "halt")) {
942 /*
943 * When the boot option of idle=halt is added, halt is
944 * forced to be used for CPU idle. In such case CPU C2/C3
945 * won't be used again.
946 * To continue to load the CPU idle driver, don't touch
947 * the boot_option_idle_override.
948 */
949 x86_idle = default_idle;
950 boot_option_idle_override = IDLE_HALT;
951 } else if (!strcmp(str, "nomwait")) {
952 /*
953 * If the boot option of "idle=nomwait" is added,
954 * it means that mwait will be disabled for CPU C1/C2/C3
955 * states.
956 */
957 boot_option_idle_override = IDLE_NOMWAIT;
958 } else
959 return -1;
960
961 return 0;
962}
963early_param("idle", idle_setup);
964
965unsigned long arch_align_stack(unsigned long sp)
966{
967 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
968 sp -= get_random_u32_below(8192);
969 return sp & ~0xf;
970}
971
972unsigned long arch_randomize_brk(struct mm_struct *mm)
973{
974 return randomize_page(mm->brk, 0x02000000);
975}
976
977/*
978 * Called from fs/proc with a reference on @p to find the function
979 * which called into schedule(). This needs to be done carefully
980 * because the task might wake up and we might look at a stack
981 * changing under us.
982 */
983unsigned long __get_wchan(struct task_struct *p)
984{
985 struct unwind_state state;
986 unsigned long addr = 0;
987
988 if (!try_get_task_stack(p))
989 return 0;
990
991 for (unwind_start(&state, p, NULL, NULL); !unwind_done(&state);
992 unwind_next_frame(&state)) {
993 addr = unwind_get_return_address(&state);
994 if (!addr)
995 break;
996 if (in_sched_functions(addr))
997 continue;
998 break;
999 }
1000
1001 put_task_stack(p);
1002
1003 return addr;
1004}
1005
1006long do_arch_prctl_common(int option, unsigned long arg2)
1007{
1008 switch (option) {
1009 case ARCH_GET_CPUID:
1010 return get_cpuid_mode();
1011 case ARCH_SET_CPUID:
1012 return set_cpuid_mode(arg2);
1013 case ARCH_GET_XCOMP_SUPP:
1014 case ARCH_GET_XCOMP_PERM:
1015 case ARCH_REQ_XCOMP_PERM:
1016 case ARCH_GET_XCOMP_GUEST_PERM:
1017 case ARCH_REQ_XCOMP_GUEST_PERM:
1018 return fpu_xstate_prctl(option, arg2);
1019 }
1020
1021 return -EINVAL;
1022}
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 <linux/uaccess.h>
32#include <asm/mwait.h>
33#include <asm/fpu/internal.h>
34#include <asm/debugreg.h>
35#include <asm/nmi.h>
36#include <asm/tlbflush.h>
37#include <asm/mce.h>
38#include <asm/vm86.h>
39#include <asm/switch_to.h>
40#include <asm/desc.h>
41#include <asm/prctl.h>
42#include <asm/spec-ctrl.h>
43#include <asm/io_bitmap.h>
44#include <asm/proto.h>
45#include <asm/frame.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};
80EXPORT_PER_CPU_SYMBOL(cpu_tss_rw);
81
82DEFINE_PER_CPU(bool, __tss_limit_invalid);
83EXPORT_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 */
89int 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 thread data structures etc..
101 */
102void 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(tsk);
109
110 free_vm86(t);
111
112 fpu__drop(fpu);
113}
114
115static 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
125int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
126 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 = encode_frame_pointer(childregs);
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 current_save_fsgs();
145 p->thread.fsindex = current->thread.fsindex;
146 p->thread.fsbase = current->thread.fsbase;
147 p->thread.gsindex = current->thread.gsindex;
148 p->thread.gsbase = current->thread.gsbase;
149
150 savesegment(es, p->thread.es);
151 savesegment(ds, p->thread.ds);
152#else
153 p->thread.sp0 = (unsigned long) (childregs + 1);
154 /*
155 * Clear all status flags including IF and set fixed bit. 64bit
156 * does not have this initialization as the frame does not contain
157 * flags. The flags consistency (especially vs. AC) is there
158 * ensured via objtool, which lacks 32bit support.
159 */
160 frame->flags = X86_EFLAGS_FIXED;
161#endif
162
163 /* Kernel thread ? */
164 if (unlikely(p->flags & PF_KTHREAD)) {
165 memset(childregs, 0, sizeof(struct pt_regs));
166 kthread_frame_init(frame, sp, arg);
167 return 0;
168 }
169
170 frame->bx = 0;
171 *childregs = *current_pt_regs();
172 childregs->ax = 0;
173 if (sp)
174 childregs->sp = sp;
175
176#ifdef CONFIG_X86_32
177 task_user_gs(p) = get_user_gs(current_pt_regs());
178#endif
179
180 /* Set a new TLS for the child thread? */
181 if (clone_flags & CLONE_SETTLS)
182 ret = set_new_tls(p, tls);
183
184 if (!ret && unlikely(test_tsk_thread_flag(current, TIF_IO_BITMAP)))
185 io_bitmap_share(p);
186
187 return ret;
188}
189
190void flush_thread(void)
191{
192 struct task_struct *tsk = current;
193
194 flush_ptrace_hw_breakpoint(tsk);
195 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
196
197 fpu__clear_all(&tsk->thread.fpu);
198}
199
200void disable_TSC(void)
201{
202 preempt_disable();
203 if (!test_and_set_thread_flag(TIF_NOTSC))
204 /*
205 * Must flip the CPU state synchronously with
206 * TIF_NOTSC in the current running context.
207 */
208 cr4_set_bits(X86_CR4_TSD);
209 preempt_enable();
210}
211
212static void enable_TSC(void)
213{
214 preempt_disable();
215 if (test_and_clear_thread_flag(TIF_NOTSC))
216 /*
217 * Must flip the CPU state synchronously with
218 * TIF_NOTSC in the current running context.
219 */
220 cr4_clear_bits(X86_CR4_TSD);
221 preempt_enable();
222}
223
224int get_tsc_mode(unsigned long adr)
225{
226 unsigned int val;
227
228 if (test_thread_flag(TIF_NOTSC))
229 val = PR_TSC_SIGSEGV;
230 else
231 val = PR_TSC_ENABLE;
232
233 return put_user(val, (unsigned int __user *)adr);
234}
235
236int set_tsc_mode(unsigned int val)
237{
238 if (val == PR_TSC_SIGSEGV)
239 disable_TSC();
240 else if (val == PR_TSC_ENABLE)
241 enable_TSC();
242 else
243 return -EINVAL;
244
245 return 0;
246}
247
248DEFINE_PER_CPU(u64, msr_misc_features_shadow);
249
250static void set_cpuid_faulting(bool on)
251{
252 u64 msrval;
253
254 msrval = this_cpu_read(msr_misc_features_shadow);
255 msrval &= ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT;
256 msrval |= (on << MSR_MISC_FEATURES_ENABLES_CPUID_FAULT_BIT);
257 this_cpu_write(msr_misc_features_shadow, msrval);
258 wrmsrl(MSR_MISC_FEATURES_ENABLES, msrval);
259}
260
261static void disable_cpuid(void)
262{
263 preempt_disable();
264 if (!test_and_set_thread_flag(TIF_NOCPUID)) {
265 /*
266 * Must flip the CPU state synchronously with
267 * TIF_NOCPUID in the current running context.
268 */
269 set_cpuid_faulting(true);
270 }
271 preempt_enable();
272}
273
274static void enable_cpuid(void)
275{
276 preempt_disable();
277 if (test_and_clear_thread_flag(TIF_NOCPUID)) {
278 /*
279 * Must flip the CPU state synchronously with
280 * TIF_NOCPUID in the current running context.
281 */
282 set_cpuid_faulting(false);
283 }
284 preempt_enable();
285}
286
287static int get_cpuid_mode(void)
288{
289 return !test_thread_flag(TIF_NOCPUID);
290}
291
292static int set_cpuid_mode(struct task_struct *task, unsigned long cpuid_enabled)
293{
294 if (!boot_cpu_has(X86_FEATURE_CPUID_FAULT))
295 return -ENODEV;
296
297 if (cpuid_enabled)
298 enable_cpuid();
299 else
300 disable_cpuid();
301
302 return 0;
303}
304
305/*
306 * Called immediately after a successful exec.
307 */
308void arch_setup_new_exec(void)
309{
310 /* If cpuid was previously disabled for this task, re-enable it. */
311 if (test_thread_flag(TIF_NOCPUID))
312 enable_cpuid();
313
314 /*
315 * Don't inherit TIF_SSBD across exec boundary when
316 * PR_SPEC_DISABLE_NOEXEC is used.
317 */
318 if (test_thread_flag(TIF_SSBD) &&
319 task_spec_ssb_noexec(current)) {
320 clear_thread_flag(TIF_SSBD);
321 task_clear_spec_ssb_disable(current);
322 task_clear_spec_ssb_noexec(current);
323 speculation_ctrl_update(task_thread_info(current)->flags);
324 }
325}
326
327#ifdef CONFIG_X86_IOPL_IOPERM
328static inline void switch_to_bitmap(unsigned long tifp)
329{
330 /*
331 * Invalidate I/O bitmap if the previous task used it. This prevents
332 * any possible leakage of an active I/O bitmap.
333 *
334 * If the next task has an I/O bitmap it will handle it on exit to
335 * user mode.
336 */
337 if (tifp & _TIF_IO_BITMAP)
338 tss_invalidate_io_bitmap();
339}
340
341static void tss_copy_io_bitmap(struct tss_struct *tss, struct io_bitmap *iobm)
342{
343 /*
344 * Copy at least the byte range of the incoming tasks bitmap which
345 * covers the permitted I/O ports.
346 *
347 * If the previous task which used an I/O bitmap had more bits
348 * permitted, then the copy needs to cover those as well so they
349 * get turned off.
350 */
351 memcpy(tss->io_bitmap.bitmap, iobm->bitmap,
352 max(tss->io_bitmap.prev_max, iobm->max));
353
354 /*
355 * Store the new max and the sequence number of this bitmap
356 * and a pointer to the bitmap itself.
357 */
358 tss->io_bitmap.prev_max = iobm->max;
359 tss->io_bitmap.prev_sequence = iobm->sequence;
360}
361
362/**
363 * tss_update_io_bitmap - Update I/O bitmap before exiting to usermode
364 */
365void native_tss_update_io_bitmap(void)
366{
367 struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw);
368 struct thread_struct *t = ¤t->thread;
369 u16 *base = &tss->x86_tss.io_bitmap_base;
370
371 if (!test_thread_flag(TIF_IO_BITMAP)) {
372 native_tss_invalidate_io_bitmap();
373 return;
374 }
375
376 if (IS_ENABLED(CONFIG_X86_IOPL_IOPERM) && t->iopl_emul == 3) {
377 *base = IO_BITMAP_OFFSET_VALID_ALL;
378 } else {
379 struct io_bitmap *iobm = t->io_bitmap;
380
381 /*
382 * Only copy bitmap data when the sequence number differs. The
383 * update time is accounted to the incoming task.
384 */
385 if (tss->io_bitmap.prev_sequence != iobm->sequence)
386 tss_copy_io_bitmap(tss, iobm);
387
388 /* Enable the bitmap */
389 *base = IO_BITMAP_OFFSET_VALID_MAP;
390 }
391
392 /*
393 * Make sure that the TSS limit is covering the IO bitmap. It might have
394 * been cut down by a VMEXIT to 0x67 which would cause a subsequent I/O
395 * access from user space to trigger a #GP because tbe bitmap is outside
396 * the TSS limit.
397 */
398 refresh_tss_limit();
399}
400#else /* CONFIG_X86_IOPL_IOPERM */
401static inline void switch_to_bitmap(unsigned long tifp) { }
402#endif
403
404#ifdef CONFIG_SMP
405
406struct ssb_state {
407 struct ssb_state *shared_state;
408 raw_spinlock_t lock;
409 unsigned int disable_state;
410 unsigned long local_state;
411};
412
413#define LSTATE_SSB 0
414
415static DEFINE_PER_CPU(struct ssb_state, ssb_state);
416
417void speculative_store_bypass_ht_init(void)
418{
419 struct ssb_state *st = this_cpu_ptr(&ssb_state);
420 unsigned int this_cpu = smp_processor_id();
421 unsigned int cpu;
422
423 st->local_state = 0;
424
425 /*
426 * Shared state setup happens once on the first bringup
427 * of the CPU. It's not destroyed on CPU hotunplug.
428 */
429 if (st->shared_state)
430 return;
431
432 raw_spin_lock_init(&st->lock);
433
434 /*
435 * Go over HT siblings and check whether one of them has set up the
436 * shared state pointer already.
437 */
438 for_each_cpu(cpu, topology_sibling_cpumask(this_cpu)) {
439 if (cpu == this_cpu)
440 continue;
441
442 if (!per_cpu(ssb_state, cpu).shared_state)
443 continue;
444
445 /* Link it to the state of the sibling: */
446 st->shared_state = per_cpu(ssb_state, cpu).shared_state;
447 return;
448 }
449
450 /*
451 * First HT sibling to come up on the core. Link shared state of
452 * the first HT sibling to itself. The siblings on the same core
453 * which come up later will see the shared state pointer and link
454 * themself to the state of this CPU.
455 */
456 st->shared_state = st;
457}
458
459/*
460 * Logic is: First HT sibling enables SSBD for both siblings in the core
461 * and last sibling to disable it, disables it for the whole core. This how
462 * MSR_SPEC_CTRL works in "hardware":
463 *
464 * CORE_SPEC_CTRL = THREAD0_SPEC_CTRL | THREAD1_SPEC_CTRL
465 */
466static __always_inline void amd_set_core_ssb_state(unsigned long tifn)
467{
468 struct ssb_state *st = this_cpu_ptr(&ssb_state);
469 u64 msr = x86_amd_ls_cfg_base;
470
471 if (!static_cpu_has(X86_FEATURE_ZEN)) {
472 msr |= ssbd_tif_to_amd_ls_cfg(tifn);
473 wrmsrl(MSR_AMD64_LS_CFG, msr);
474 return;
475 }
476
477 if (tifn & _TIF_SSBD) {
478 /*
479 * Since this can race with prctl(), block reentry on the
480 * same CPU.
481 */
482 if (__test_and_set_bit(LSTATE_SSB, &st->local_state))
483 return;
484
485 msr |= x86_amd_ls_cfg_ssbd_mask;
486
487 raw_spin_lock(&st->shared_state->lock);
488 /* First sibling enables SSBD: */
489 if (!st->shared_state->disable_state)
490 wrmsrl(MSR_AMD64_LS_CFG, msr);
491 st->shared_state->disable_state++;
492 raw_spin_unlock(&st->shared_state->lock);
493 } else {
494 if (!__test_and_clear_bit(LSTATE_SSB, &st->local_state))
495 return;
496
497 raw_spin_lock(&st->shared_state->lock);
498 st->shared_state->disable_state--;
499 if (!st->shared_state->disable_state)
500 wrmsrl(MSR_AMD64_LS_CFG, msr);
501 raw_spin_unlock(&st->shared_state->lock);
502 }
503}
504#else
505static __always_inline void amd_set_core_ssb_state(unsigned long tifn)
506{
507 u64 msr = x86_amd_ls_cfg_base | ssbd_tif_to_amd_ls_cfg(tifn);
508
509 wrmsrl(MSR_AMD64_LS_CFG, msr);
510}
511#endif
512
513static __always_inline void amd_set_ssb_virt_state(unsigned long tifn)
514{
515 /*
516 * SSBD has the same definition in SPEC_CTRL and VIRT_SPEC_CTRL,
517 * so ssbd_tif_to_spec_ctrl() just works.
518 */
519 wrmsrl(MSR_AMD64_VIRT_SPEC_CTRL, ssbd_tif_to_spec_ctrl(tifn));
520}
521
522/*
523 * Update the MSRs managing speculation control, during context switch.
524 *
525 * tifp: Previous task's thread flags
526 * tifn: Next task's thread flags
527 */
528static __always_inline void __speculation_ctrl_update(unsigned long tifp,
529 unsigned long tifn)
530{
531 unsigned long tif_diff = tifp ^ tifn;
532 u64 msr = x86_spec_ctrl_base;
533 bool updmsr = false;
534
535 lockdep_assert_irqs_disabled();
536
537 /* Handle change of TIF_SSBD depending on the mitigation method. */
538 if (static_cpu_has(X86_FEATURE_VIRT_SSBD)) {
539 if (tif_diff & _TIF_SSBD)
540 amd_set_ssb_virt_state(tifn);
541 } else if (static_cpu_has(X86_FEATURE_LS_CFG_SSBD)) {
542 if (tif_diff & _TIF_SSBD)
543 amd_set_core_ssb_state(tifn);
544 } else if (static_cpu_has(X86_FEATURE_SPEC_CTRL_SSBD) ||
545 static_cpu_has(X86_FEATURE_AMD_SSBD)) {
546 updmsr |= !!(tif_diff & _TIF_SSBD);
547 msr |= ssbd_tif_to_spec_ctrl(tifn);
548 }
549
550 /* Only evaluate TIF_SPEC_IB if conditional STIBP is enabled. */
551 if (IS_ENABLED(CONFIG_SMP) &&
552 static_branch_unlikely(&switch_to_cond_stibp)) {
553 updmsr |= !!(tif_diff & _TIF_SPEC_IB);
554 msr |= stibp_tif_to_spec_ctrl(tifn);
555 }
556
557 if (updmsr)
558 wrmsrl(MSR_IA32_SPEC_CTRL, msr);
559}
560
561static unsigned long speculation_ctrl_update_tif(struct task_struct *tsk)
562{
563 if (test_and_clear_tsk_thread_flag(tsk, TIF_SPEC_FORCE_UPDATE)) {
564 if (task_spec_ssb_disable(tsk))
565 set_tsk_thread_flag(tsk, TIF_SSBD);
566 else
567 clear_tsk_thread_flag(tsk, TIF_SSBD);
568
569 if (task_spec_ib_disable(tsk))
570 set_tsk_thread_flag(tsk, TIF_SPEC_IB);
571 else
572 clear_tsk_thread_flag(tsk, TIF_SPEC_IB);
573 }
574 /* Return the updated threadinfo flags*/
575 return task_thread_info(tsk)->flags;
576}
577
578void speculation_ctrl_update(unsigned long tif)
579{
580 unsigned long flags;
581
582 /* Forced update. Make sure all relevant TIF flags are different */
583 local_irq_save(flags);
584 __speculation_ctrl_update(~tif, tif);
585 local_irq_restore(flags);
586}
587
588/* Called from seccomp/prctl update */
589void speculation_ctrl_update_current(void)
590{
591 preempt_disable();
592 speculation_ctrl_update(speculation_ctrl_update_tif(current));
593 preempt_enable();
594}
595
596static inline void cr4_toggle_bits_irqsoff(unsigned long mask)
597{
598 unsigned long newval, cr4 = this_cpu_read(cpu_tlbstate.cr4);
599
600 newval = cr4 ^ mask;
601 if (newval != cr4) {
602 this_cpu_write(cpu_tlbstate.cr4, newval);
603 __write_cr4(newval);
604 }
605}
606
607void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
608{
609 unsigned long tifp, tifn;
610
611 tifn = READ_ONCE(task_thread_info(next_p)->flags);
612 tifp = READ_ONCE(task_thread_info(prev_p)->flags);
613
614 switch_to_bitmap(tifp);
615
616 propagate_user_return_notify(prev_p, next_p);
617
618 if ((tifp & _TIF_BLOCKSTEP || tifn & _TIF_BLOCKSTEP) &&
619 arch_has_block_step()) {
620 unsigned long debugctl, msk;
621
622 rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
623 debugctl &= ~DEBUGCTLMSR_BTF;
624 msk = tifn & _TIF_BLOCKSTEP;
625 debugctl |= (msk >> TIF_BLOCKSTEP) << DEBUGCTLMSR_BTF_SHIFT;
626 wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
627 }
628
629 if ((tifp ^ tifn) & _TIF_NOTSC)
630 cr4_toggle_bits_irqsoff(X86_CR4_TSD);
631
632 if ((tifp ^ tifn) & _TIF_NOCPUID)
633 set_cpuid_faulting(!!(tifn & _TIF_NOCPUID));
634
635 if (likely(!((tifp | tifn) & _TIF_SPEC_FORCE_UPDATE))) {
636 __speculation_ctrl_update(tifp, tifn);
637 } else {
638 speculation_ctrl_update_tif(prev_p);
639 tifn = speculation_ctrl_update_tif(next_p);
640
641 /* Enforce MSR update to ensure consistent state */
642 __speculation_ctrl_update(~tifn, tifn);
643 }
644
645 if ((tifp ^ tifn) & _TIF_SLD)
646 switch_to_sld(tifn);
647}
648
649/*
650 * Idle related variables and functions
651 */
652unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
653EXPORT_SYMBOL(boot_option_idle_override);
654
655static void (*x86_idle)(void);
656
657#ifndef CONFIG_SMP
658static inline void play_dead(void)
659{
660 BUG();
661}
662#endif
663
664void arch_cpu_idle_enter(void)
665{
666 tsc_verify_tsc_adjust(false);
667 local_touch_nmi();
668}
669
670void arch_cpu_idle_dead(void)
671{
672 play_dead();
673}
674
675/*
676 * Called from the generic idle code.
677 */
678void arch_cpu_idle(void)
679{
680 x86_idle();
681}
682
683/*
684 * We use this if we don't have any better idle routine..
685 */
686void __cpuidle default_idle(void)
687{
688 safe_halt();
689}
690#if defined(CONFIG_APM_MODULE) || defined(CONFIG_HALTPOLL_CPUIDLE_MODULE)
691EXPORT_SYMBOL(default_idle);
692#endif
693
694#ifdef CONFIG_XEN
695bool xen_set_default_idle(void)
696{
697 bool ret = !!x86_idle;
698
699 x86_idle = default_idle;
700
701 return ret;
702}
703#endif
704
705void stop_this_cpu(void *dummy)
706{
707 local_irq_disable();
708 /*
709 * Remove this CPU:
710 */
711 set_cpu_online(smp_processor_id(), false);
712 disable_local_APIC();
713 mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
714
715 /*
716 * Use wbinvd on processors that support SME. This provides support
717 * for performing a successful kexec when going from SME inactive
718 * to SME active (or vice-versa). The cache must be cleared so that
719 * if there are entries with the same physical address, both with and
720 * without the encryption bit, they don't race each other when flushed
721 * and potentially end up with the wrong entry being committed to
722 * memory.
723 */
724 if (boot_cpu_has(X86_FEATURE_SME))
725 native_wbinvd();
726 for (;;) {
727 /*
728 * Use native_halt() so that memory contents don't change
729 * (stack usage and variables) after possibly issuing the
730 * native_wbinvd() above.
731 */
732 native_halt();
733 }
734}
735
736/*
737 * AMD Erratum 400 aware idle routine. We handle it the same way as C3 power
738 * states (local apic timer and TSC stop).
739 */
740static void amd_e400_idle(void)
741{
742 /*
743 * We cannot use static_cpu_has_bug() here because X86_BUG_AMD_APIC_C1E
744 * gets set after static_cpu_has() places have been converted via
745 * alternatives.
746 */
747 if (!boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) {
748 default_idle();
749 return;
750 }
751
752 tick_broadcast_enter();
753
754 default_idle();
755
756 /*
757 * The switch back from broadcast mode needs to be called with
758 * interrupts disabled.
759 */
760 local_irq_disable();
761 tick_broadcast_exit();
762 local_irq_enable();
763}
764
765/*
766 * Intel Core2 and older machines prefer MWAIT over HALT for C1.
767 * We can't rely on cpuidle installing MWAIT, because it will not load
768 * on systems that support only C1 -- so the boot default must be MWAIT.
769 *
770 * Some AMD machines are the opposite, they depend on using HALT.
771 *
772 * So for default C1, which is used during boot until cpuidle loads,
773 * use MWAIT-C1 on Intel HW that has it, else use HALT.
774 */
775static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
776{
777 if (c->x86_vendor != X86_VENDOR_INTEL)
778 return 0;
779
780 if (!cpu_has(c, X86_FEATURE_MWAIT) || boot_cpu_has_bug(X86_BUG_MONITOR))
781 return 0;
782
783 return 1;
784}
785
786/*
787 * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT
788 * with interrupts enabled and no flags, which is backwards compatible with the
789 * original MWAIT implementation.
790 */
791static __cpuidle void mwait_idle(void)
792{
793 if (!current_set_polling_and_test()) {
794 if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
795 mb(); /* quirk */
796 clflush((void *)¤t_thread_info()->flags);
797 mb(); /* quirk */
798 }
799
800 __monitor((void *)¤t_thread_info()->flags, 0, 0);
801 if (!need_resched())
802 __sti_mwait(0, 0);
803 else
804 local_irq_enable();
805 } else {
806 local_irq_enable();
807 }
808 __current_clr_polling();
809}
810
811void select_idle_routine(const struct cpuinfo_x86 *c)
812{
813#ifdef CONFIG_SMP
814 if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
815 pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
816#endif
817 if (x86_idle || boot_option_idle_override == IDLE_POLL)
818 return;
819
820 if (boot_cpu_has_bug(X86_BUG_AMD_E400)) {
821 pr_info("using AMD E400 aware idle routine\n");
822 x86_idle = amd_e400_idle;
823 } else if (prefer_mwait_c1_over_halt(c)) {
824 pr_info("using mwait in idle threads\n");
825 x86_idle = mwait_idle;
826 } else
827 x86_idle = default_idle;
828}
829
830void amd_e400_c1e_apic_setup(void)
831{
832 if (boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) {
833 pr_info("Switch to broadcast mode on CPU%d\n", smp_processor_id());
834 local_irq_disable();
835 tick_broadcast_force();
836 local_irq_enable();
837 }
838}
839
840void __init arch_post_acpi_subsys_init(void)
841{
842 u32 lo, hi;
843
844 if (!boot_cpu_has_bug(X86_BUG_AMD_E400))
845 return;
846
847 /*
848 * AMD E400 detection needs to happen after ACPI has been enabled. If
849 * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in
850 * MSR_K8_INT_PENDING_MSG.
851 */
852 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
853 if (!(lo & K8_INTP_C1E_ACTIVE_MASK))
854 return;
855
856 boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E);
857
858 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
859 mark_tsc_unstable("TSC halt in AMD C1E");
860 pr_info("System has AMD C1E enabled\n");
861}
862
863static int __init idle_setup(char *str)
864{
865 if (!str)
866 return -EINVAL;
867
868 if (!strcmp(str, "poll")) {
869 pr_info("using polling idle threads\n");
870 boot_option_idle_override = IDLE_POLL;
871 cpu_idle_poll_ctrl(true);
872 } else if (!strcmp(str, "halt")) {
873 /*
874 * When the boot option of idle=halt is added, halt is
875 * forced to be used for CPU idle. In such case CPU C2/C3
876 * won't be used again.
877 * To continue to load the CPU idle driver, don't touch
878 * the boot_option_idle_override.
879 */
880 x86_idle = default_idle;
881 boot_option_idle_override = IDLE_HALT;
882 } else if (!strcmp(str, "nomwait")) {
883 /*
884 * If the boot option of "idle=nomwait" is added,
885 * it means that mwait will be disabled for CPU C2/C3
886 * states. In such case it won't touch the variable
887 * of boot_option_idle_override.
888 */
889 boot_option_idle_override = IDLE_NOMWAIT;
890 } else
891 return -1;
892
893 return 0;
894}
895early_param("idle", idle_setup);
896
897unsigned long arch_align_stack(unsigned long sp)
898{
899 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
900 sp -= get_random_int() % 8192;
901 return sp & ~0xf;
902}
903
904unsigned long arch_randomize_brk(struct mm_struct *mm)
905{
906 return randomize_page(mm->brk, 0x02000000);
907}
908
909/*
910 * Called from fs/proc with a reference on @p to find the function
911 * which called into schedule(). This needs to be done carefully
912 * because the task might wake up and we might look at a stack
913 * changing under us.
914 */
915unsigned long get_wchan(struct task_struct *p)
916{
917 unsigned long start, bottom, top, sp, fp, ip, ret = 0;
918 int count = 0;
919
920 if (p == current || p->state == TASK_RUNNING)
921 return 0;
922
923 if (!try_get_task_stack(p))
924 return 0;
925
926 start = (unsigned long)task_stack_page(p);
927 if (!start)
928 goto out;
929
930 /*
931 * Layout of the stack page:
932 *
933 * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)
934 * PADDING
935 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
936 * stack
937 * ----------- bottom = start
938 *
939 * The tasks stack pointer points at the location where the
940 * framepointer is stored. The data on the stack is:
941 * ... IP FP ... IP FP
942 *
943 * We need to read FP and IP, so we need to adjust the upper
944 * bound by another unsigned long.
945 */
946 top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;
947 top -= 2 * sizeof(unsigned long);
948 bottom = start;
949
950 sp = READ_ONCE(p->thread.sp);
951 if (sp < bottom || sp > top)
952 goto out;
953
954 fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp);
955 do {
956 if (fp < bottom || fp > top)
957 goto out;
958 ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
959 if (!in_sched_functions(ip)) {
960 ret = ip;
961 goto out;
962 }
963 fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
964 } while (count++ < 16 && p->state != TASK_RUNNING);
965
966out:
967 put_task_stack(p);
968 return ret;
969}
970
971long do_arch_prctl_common(struct task_struct *task, int option,
972 unsigned long cpuid_enabled)
973{
974 switch (option) {
975 case ARCH_GET_CPUID:
976 return get_cpuid_mode();
977 case ARCH_SET_CPUID:
978 return set_cpuid_mode(task, cpuid_enabled);
979 }
980
981 return -EINVAL;
982}