1 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
3 #include <linux/errno.h>
4 #include <linux/kernel.h>
7 #include <linux/prctl.h>
8 #include <linux/slab.h>
9 #include <linux/sched.h>
10 #include <linux/sched/idle.h>
11 #include <linux/sched/debug.h>
12 #include <linux/sched/task.h>
13 #include <linux/sched/task_stack.h>
14 #include <linux/init.h>
15 #include <linux/export.h>
17 #include <linux/tick.h>
18 #include <linux/random.h>
19 #include <linux/user-return-notifier.h>
20 #include <linux/dmi.h>
21 #include <linux/utsname.h>
22 #include <linux/stackprotector.h>
23 #include <linux/tick.h>
24 #include <linux/cpuidle.h>
25 #include <trace/events/power.h>
26 #include <linux/hw_breakpoint.h>
29 #include <asm/syscalls.h>
30 #include <linux/uaccess.h>
31 #include <asm/mwait.h>
32 #include <asm/fpu/internal.h>
33 #include <asm/debugreg.h>
35 #include <asm/tlbflush.h>
38 #include <asm/switch_to.h>
40 #include <asm/prctl.h>
43 * per-CPU TSS segments. Threads are completely 'soft' on Linux,
44 * no more per-task TSS's. The TSS size is kept cacheline-aligned
45 * so they are allowed to end up in the .data..cacheline_aligned
46 * section. Since TSS's are completely CPU-local, we want them
47 * on exact cacheline boundaries, to eliminate cacheline ping-pong.
49 __visible
DEFINE_PER_CPU_PAGE_ALIGNED(struct tss_struct
, cpu_tss_rw
) = {
52 * .sp0 is only used when entering ring 0 from a lower
53 * privilege level. Since the init task never runs anything
54 * but ring 0 code, there is no need for a valid value here.
57 .sp0
= (1UL << (BITS_PER_LONG
-1)) + 1,
61 * .sp1 is cpu_current_top_of_stack. The init task never
62 * runs user code, but cpu_current_top_of_stack should still
63 * be well defined before the first context switch.
65 .sp1
= TOP_OF_INIT_STACK
,
71 .io_bitmap_base
= INVALID_IO_BITMAP_OFFSET
,
76 * Note that the .io_bitmap member must be extra-big. This is because
77 * the CPU will access an additional byte beyond the end of the IO
78 * permission bitmap. The extra byte must be all 1 bits, and must
79 * be within the limit.
81 .io_bitmap
= { [0 ... IO_BITMAP_LONGS
] = ~0 },
84 EXPORT_PER_CPU_SYMBOL(cpu_tss_rw
);
86 DEFINE_PER_CPU(bool, __tss_limit_invalid
);
87 EXPORT_PER_CPU_SYMBOL_GPL(__tss_limit_invalid
);
90 * this gets called so that we can store lazy state into memory and copy the
91 * current task into the new thread.
93 int arch_dup_task_struct(struct task_struct
*dst
, struct task_struct
*src
)
95 memcpy(dst
, src
, arch_task_struct_size
);
97 dst
->thread
.vm86
= NULL
;
100 return fpu__copy(&dst
->thread
.fpu
, &src
->thread
.fpu
);
104 * Free current thread data structures etc..
106 void exit_thread(struct task_struct
*tsk
)
108 struct thread_struct
*t
= &tsk
->thread
;
109 unsigned long *bp
= t
->io_bitmap_ptr
;
110 struct fpu
*fpu
= &t
->fpu
;
113 struct tss_struct
*tss
= &per_cpu(cpu_tss_rw
, get_cpu());
115 t
->io_bitmap_ptr
= NULL
;
116 clear_thread_flag(TIF_IO_BITMAP
);
118 * Careful, clear this in the TSS too:
120 memset(tss
->io_bitmap
, 0xff, t
->io_bitmap_max
);
121 t
->io_bitmap_max
= 0;
131 void flush_thread(void)
133 struct task_struct
*tsk
= current
;
135 flush_ptrace_hw_breakpoint(tsk
);
136 memset(tsk
->thread
.tls_array
, 0, sizeof(tsk
->thread
.tls_array
));
138 fpu__clear(&tsk
->thread
.fpu
);
141 void disable_TSC(void)
144 if (!test_and_set_thread_flag(TIF_NOTSC
))
146 * Must flip the CPU state synchronously with
147 * TIF_NOTSC in the current running context.
149 cr4_set_bits(X86_CR4_TSD
);
153 static void enable_TSC(void)
156 if (test_and_clear_thread_flag(TIF_NOTSC
))
158 * Must flip the CPU state synchronously with
159 * TIF_NOTSC in the current running context.
161 cr4_clear_bits(X86_CR4_TSD
);
165 int get_tsc_mode(unsigned long adr
)
169 if (test_thread_flag(TIF_NOTSC
))
170 val
= PR_TSC_SIGSEGV
;
174 return put_user(val
, (unsigned int __user
*)adr
);
177 int set_tsc_mode(unsigned int val
)
179 if (val
== PR_TSC_SIGSEGV
)
181 else if (val
== PR_TSC_ENABLE
)
189 DEFINE_PER_CPU(u64
, msr_misc_features_shadow
);
191 static void set_cpuid_faulting(bool on
)
195 msrval
= this_cpu_read(msr_misc_features_shadow
);
196 msrval
&= ~MSR_MISC_FEATURES_ENABLES_CPUID_FAULT
;
197 msrval
|= (on
<< MSR_MISC_FEATURES_ENABLES_CPUID_FAULT_BIT
);
198 this_cpu_write(msr_misc_features_shadow
, msrval
);
199 wrmsrl(MSR_MISC_FEATURES_ENABLES
, msrval
);
202 static void disable_cpuid(void)
205 if (!test_and_set_thread_flag(TIF_NOCPUID
)) {
207 * Must flip the CPU state synchronously with
208 * TIF_NOCPUID in the current running context.
210 set_cpuid_faulting(true);
215 static void enable_cpuid(void)
218 if (test_and_clear_thread_flag(TIF_NOCPUID
)) {
220 * Must flip the CPU state synchronously with
221 * TIF_NOCPUID in the current running context.
223 set_cpuid_faulting(false);
228 static int get_cpuid_mode(void)
230 return !test_thread_flag(TIF_NOCPUID
);
233 static int set_cpuid_mode(struct task_struct
*task
, unsigned long cpuid_enabled
)
235 if (!static_cpu_has(X86_FEATURE_CPUID_FAULT
))
247 * Called immediately after a successful exec.
249 void arch_setup_new_exec(void)
251 /* If cpuid was previously disabled for this task, re-enable it. */
252 if (test_thread_flag(TIF_NOCPUID
))
256 static inline void switch_to_bitmap(struct tss_struct
*tss
,
257 struct thread_struct
*prev
,
258 struct thread_struct
*next
,
259 unsigned long tifp
, unsigned long tifn
)
261 if (tifn
& _TIF_IO_BITMAP
) {
263 * Copy the relevant range of the IO bitmap.
264 * Normally this is 128 bytes or less:
266 memcpy(tss
->io_bitmap
, next
->io_bitmap_ptr
,
267 max(prev
->io_bitmap_max
, next
->io_bitmap_max
));
269 * Make sure that the TSS limit is correct for the CPU
270 * to notice the IO bitmap.
273 } else if (tifp
& _TIF_IO_BITMAP
) {
275 * Clear any possible leftover bits:
277 memset(tss
->io_bitmap
, 0xff, prev
->io_bitmap_max
);
281 void __switch_to_xtra(struct task_struct
*prev_p
, struct task_struct
*next_p
,
282 struct tss_struct
*tss
)
284 struct thread_struct
*prev
, *next
;
285 unsigned long tifp
, tifn
;
287 prev
= &prev_p
->thread
;
288 next
= &next_p
->thread
;
290 tifn
= READ_ONCE(task_thread_info(next_p
)->flags
);
291 tifp
= READ_ONCE(task_thread_info(prev_p
)->flags
);
292 switch_to_bitmap(tss
, prev
, next
, tifp
, tifn
);
294 propagate_user_return_notify(prev_p
, next_p
);
296 if ((tifp
& _TIF_BLOCKSTEP
|| tifn
& _TIF_BLOCKSTEP
) &&
297 arch_has_block_step()) {
298 unsigned long debugctl
, msk
;
300 rdmsrl(MSR_IA32_DEBUGCTLMSR
, debugctl
);
301 debugctl
&= ~DEBUGCTLMSR_BTF
;
302 msk
= tifn
& _TIF_BLOCKSTEP
;
303 debugctl
|= (msk
>> TIF_BLOCKSTEP
) << DEBUGCTLMSR_BTF_SHIFT
;
304 wrmsrl(MSR_IA32_DEBUGCTLMSR
, debugctl
);
307 if ((tifp
^ tifn
) & _TIF_NOTSC
)
308 cr4_toggle_bits(X86_CR4_TSD
);
310 if ((tifp
^ tifn
) & _TIF_NOCPUID
)
311 set_cpuid_faulting(!!(tifn
& _TIF_NOCPUID
));
315 * Idle related variables and functions
317 unsigned long boot_option_idle_override
= IDLE_NO_OVERRIDE
;
318 EXPORT_SYMBOL(boot_option_idle_override
);
320 static void (*x86_idle
)(void);
323 static inline void play_dead(void)
329 void arch_cpu_idle_enter(void)
331 tsc_verify_tsc_adjust(false);
335 void arch_cpu_idle_dead(void)
341 * Called from the generic idle code.
343 void arch_cpu_idle(void)
349 * We use this if we don't have any better idle routine..
351 void __cpuidle
default_idle(void)
353 trace_cpu_idle_rcuidle(1, smp_processor_id());
355 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT
, smp_processor_id());
357 #ifdef CONFIG_APM_MODULE
358 EXPORT_SYMBOL(default_idle
);
362 bool xen_set_default_idle(void)
364 bool ret
= !!x86_idle
;
366 x86_idle
= default_idle
;
371 void stop_this_cpu(void *dummy
)
377 set_cpu_online(smp_processor_id(), false);
378 disable_local_APIC();
379 mcheck_cpu_clear(this_cpu_ptr(&cpu_info
));
386 * AMD Erratum 400 aware idle routine. We handle it the same way as C3 power
387 * states (local apic timer and TSC stop).
389 static void amd_e400_idle(void)
392 * We cannot use static_cpu_has_bug() here because X86_BUG_AMD_APIC_C1E
393 * gets set after static_cpu_has() places have been converted via
396 if (!boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E
)) {
401 tick_broadcast_enter();
406 * The switch back from broadcast mode needs to be called with
407 * interrupts disabled.
410 tick_broadcast_exit();
415 * Intel Core2 and older machines prefer MWAIT over HALT for C1.
416 * We can't rely on cpuidle installing MWAIT, because it will not load
417 * on systems that support only C1 -- so the boot default must be MWAIT.
419 * Some AMD machines are the opposite, they depend on using HALT.
421 * So for default C1, which is used during boot until cpuidle loads,
422 * use MWAIT-C1 on Intel HW that has it, else use HALT.
424 static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86
*c
)
426 if (c
->x86_vendor
!= X86_VENDOR_INTEL
)
429 if (!cpu_has(c
, X86_FEATURE_MWAIT
) || static_cpu_has_bug(X86_BUG_MONITOR
))
436 * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT
437 * with interrupts enabled and no flags, which is backwards compatible with the
438 * original MWAIT implementation.
440 static __cpuidle
void mwait_idle(void)
442 if (!current_set_polling_and_test()) {
443 trace_cpu_idle_rcuidle(1, smp_processor_id());
444 if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR
)) {
446 clflush((void *)¤t_thread_info()->flags
);
450 __monitor((void *)¤t_thread_info()->flags
, 0, 0);
455 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT
, smp_processor_id());
459 __current_clr_polling();
462 void select_idle_routine(const struct cpuinfo_x86
*c
)
465 if (boot_option_idle_override
== IDLE_POLL
&& smp_num_siblings
> 1)
466 pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
468 if (x86_idle
|| boot_option_idle_override
== IDLE_POLL
)
471 if (boot_cpu_has_bug(X86_BUG_AMD_E400
)) {
472 pr_info("using AMD E400 aware idle routine\n");
473 x86_idle
= amd_e400_idle
;
474 } else if (prefer_mwait_c1_over_halt(c
)) {
475 pr_info("using mwait in idle threads\n");
476 x86_idle
= mwait_idle
;
478 x86_idle
= default_idle
;
481 void amd_e400_c1e_apic_setup(void)
483 if (boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E
)) {
484 pr_info("Switch to broadcast mode on CPU%d\n", smp_processor_id());
486 tick_broadcast_force();
491 void __init
arch_post_acpi_subsys_init(void)
495 if (!boot_cpu_has_bug(X86_BUG_AMD_E400
))
499 * AMD E400 detection needs to happen after ACPI has been enabled. If
500 * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in
501 * MSR_K8_INT_PENDING_MSG.
503 rdmsr(MSR_K8_INT_PENDING_MSG
, lo
, hi
);
504 if (!(lo
& K8_INTP_C1E_ACTIVE_MASK
))
507 boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E
);
509 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC
))
510 mark_tsc_unstable("TSC halt in AMD C1E");
511 pr_info("System has AMD C1E enabled\n");
514 static int __init
idle_setup(char *str
)
519 if (!strcmp(str
, "poll")) {
520 pr_info("using polling idle threads\n");
521 boot_option_idle_override
= IDLE_POLL
;
522 cpu_idle_poll_ctrl(true);
523 } else if (!strcmp(str
, "halt")) {
525 * When the boot option of idle=halt is added, halt is
526 * forced to be used for CPU idle. In such case CPU C2/C3
527 * won't be used again.
528 * To continue to load the CPU idle driver, don't touch
529 * the boot_option_idle_override.
531 x86_idle
= default_idle
;
532 boot_option_idle_override
= IDLE_HALT
;
533 } else if (!strcmp(str
, "nomwait")) {
535 * If the boot option of "idle=nomwait" is added,
536 * it means that mwait will be disabled for CPU C2/C3
537 * states. In such case it won't touch the variable
538 * of boot_option_idle_override.
540 boot_option_idle_override
= IDLE_NOMWAIT
;
546 early_param("idle", idle_setup
);
548 unsigned long arch_align_stack(unsigned long sp
)
550 if (!(current
->personality
& ADDR_NO_RANDOMIZE
) && randomize_va_space
)
551 sp
-= get_random_int() % 8192;
555 unsigned long arch_randomize_brk(struct mm_struct
*mm
)
557 return randomize_page(mm
->brk
, 0x02000000);
561 * Called from fs/proc with a reference on @p to find the function
562 * which called into schedule(). This needs to be done carefully
563 * because the task might wake up and we might look at a stack
566 unsigned long get_wchan(struct task_struct
*p
)
568 unsigned long start
, bottom
, top
, sp
, fp
, ip
, ret
= 0;
571 if (!p
|| p
== current
|| p
->state
== TASK_RUNNING
)
574 if (!try_get_task_stack(p
))
577 start
= (unsigned long)task_stack_page(p
);
582 * Layout of the stack page:
584 * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)
586 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
588 * ----------- bottom = start
590 * The tasks stack pointer points at the location where the
591 * framepointer is stored. The data on the stack is:
592 * ... IP FP ... IP FP
594 * We need to read FP and IP, so we need to adjust the upper
595 * bound by another unsigned long.
597 top
= start
+ THREAD_SIZE
- TOP_OF_KERNEL_STACK_PADDING
;
598 top
-= 2 * sizeof(unsigned long);
601 sp
= READ_ONCE(p
->thread
.sp
);
602 if (sp
< bottom
|| sp
> top
)
605 fp
= READ_ONCE_NOCHECK(((struct inactive_task_frame
*)sp
)->bp
);
607 if (fp
< bottom
|| fp
> top
)
609 ip
= READ_ONCE_NOCHECK(*(unsigned long *)(fp
+ sizeof(unsigned long)));
610 if (!in_sched_functions(ip
)) {
614 fp
= READ_ONCE_NOCHECK(*(unsigned long *)fp
);
615 } while (count
++ < 16 && p
->state
!= TASK_RUNNING
);
622 long do_arch_prctl_common(struct task_struct
*task
, int option
,
623 unsigned long cpuid_enabled
)
627 return get_cpuid_mode();
629 return set_cpuid_mode(task
, cpuid_enabled
);