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1#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
2
3#include <linux/errno.h>
4#include <linux/kernel.h>
5#include <linux/mm.h>
6#include <linux/smp.h>
7#include <linux/prctl.h>
8#include <linux/slab.h>
9#include <linux/sched.h>
10#include <linux/init.h>
11#include <linux/export.h>
12#include <linux/pm.h>
13#include <linux/tick.h>
14#include <linux/random.h>
15#include <linux/user-return-notifier.h>
16#include <linux/dmi.h>
17#include <linux/utsname.h>
18#include <linux/stackprotector.h>
19#include <linux/tick.h>
20#include <linux/cpuidle.h>
21#include <trace/events/power.h>
22#include <linux/hw_breakpoint.h>
23#include <asm/cpu.h>
24#include <asm/apic.h>
25#include <asm/syscalls.h>
26#include <linux/uaccess.h>
27#include <asm/mwait.h>
28#include <asm/fpu/internal.h>
29#include <asm/debugreg.h>
30#include <asm/nmi.h>
31#include <asm/tlbflush.h>
32#include <asm/mce.h>
33#include <asm/vm86.h>
34#include <asm/switch_to.h>
35
36/*
37 * per-CPU TSS segments. Threads are completely 'soft' on Linux,
38 * no more per-task TSS's. The TSS size is kept cacheline-aligned
39 * so they are allowed to end up in the .data..cacheline_aligned
40 * section. Since TSS's are completely CPU-local, we want them
41 * on exact cacheline boundaries, to eliminate cacheline ping-pong.
42 */
43__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
44 .x86_tss = {
45 .sp0 = TOP_OF_INIT_STACK,
46#ifdef CONFIG_X86_32
47 .ss0 = __KERNEL_DS,
48 .ss1 = __KERNEL_CS,
49 .io_bitmap_base = INVALID_IO_BITMAP_OFFSET,
50#endif
51 },
52#ifdef CONFIG_X86_32
53 /*
54 * Note that the .io_bitmap member must be extra-big. This is because
55 * the CPU will access an additional byte beyond the end of the IO
56 * permission bitmap. The extra byte must be all 1 bits, and must
57 * be within the limit.
58 */
59 .io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 },
60#endif
61#ifdef CONFIG_X86_32
62 .SYSENTER_stack_canary = STACK_END_MAGIC,
63#endif
64};
65EXPORT_PER_CPU_SYMBOL(cpu_tss);
66
67/*
68 * this gets called so that we can store lazy state into memory and copy the
69 * current task into the new thread.
70 */
71int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
72{
73 memcpy(dst, src, arch_task_struct_size);
74#ifdef CONFIG_VM86
75 dst->thread.vm86 = NULL;
76#endif
77
78 return fpu__copy(&dst->thread.fpu, &src->thread.fpu);
79}
80
81/*
82 * Free current thread data structures etc..
83 */
84void exit_thread(struct task_struct *tsk)
85{
86 struct thread_struct *t = &tsk->thread;
87 unsigned long *bp = t->io_bitmap_ptr;
88 struct fpu *fpu = &t->fpu;
89
90 if (bp) {
91 struct tss_struct *tss = &per_cpu(cpu_tss, get_cpu());
92
93 t->io_bitmap_ptr = NULL;
94 clear_thread_flag(TIF_IO_BITMAP);
95 /*
96 * Careful, clear this in the TSS too:
97 */
98 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
99 t->io_bitmap_max = 0;
100 put_cpu();
101 kfree(bp);
102 }
103
104 free_vm86(t);
105
106 fpu__drop(fpu);
107}
108
109void flush_thread(void)
110{
111 struct task_struct *tsk = current;
112
113 flush_ptrace_hw_breakpoint(tsk);
114 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
115
116 fpu__clear(&tsk->thread.fpu);
117}
118
119static void hard_disable_TSC(void)
120{
121 cr4_set_bits(X86_CR4_TSD);
122}
123
124void disable_TSC(void)
125{
126 preempt_disable();
127 if (!test_and_set_thread_flag(TIF_NOTSC))
128 /*
129 * Must flip the CPU state synchronously with
130 * TIF_NOTSC in the current running context.
131 */
132 hard_disable_TSC();
133 preempt_enable();
134}
135
136static void hard_enable_TSC(void)
137{
138 cr4_clear_bits(X86_CR4_TSD);
139}
140
141static void enable_TSC(void)
142{
143 preempt_disable();
144 if (test_and_clear_thread_flag(TIF_NOTSC))
145 /*
146 * Must flip the CPU state synchronously with
147 * TIF_NOTSC in the current running context.
148 */
149 hard_enable_TSC();
150 preempt_enable();
151}
152
153int get_tsc_mode(unsigned long adr)
154{
155 unsigned int val;
156
157 if (test_thread_flag(TIF_NOTSC))
158 val = PR_TSC_SIGSEGV;
159 else
160 val = PR_TSC_ENABLE;
161
162 return put_user(val, (unsigned int __user *)adr);
163}
164
165int set_tsc_mode(unsigned int val)
166{
167 if (val == PR_TSC_SIGSEGV)
168 disable_TSC();
169 else if (val == PR_TSC_ENABLE)
170 enable_TSC();
171 else
172 return -EINVAL;
173
174 return 0;
175}
176
177void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
178 struct tss_struct *tss)
179{
180 struct thread_struct *prev, *next;
181
182 prev = &prev_p->thread;
183 next = &next_p->thread;
184
185 if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
186 test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
187 unsigned long debugctl = get_debugctlmsr();
188
189 debugctl &= ~DEBUGCTLMSR_BTF;
190 if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
191 debugctl |= DEBUGCTLMSR_BTF;
192
193 update_debugctlmsr(debugctl);
194 }
195
196 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
197 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
198 /* prev and next are different */
199 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
200 hard_disable_TSC();
201 else
202 hard_enable_TSC();
203 }
204
205 if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
206 /*
207 * Copy the relevant range of the IO bitmap.
208 * Normally this is 128 bytes or less:
209 */
210 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
211 max(prev->io_bitmap_max, next->io_bitmap_max));
212 } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
213 /*
214 * Clear any possible leftover bits:
215 */
216 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
217 }
218 propagate_user_return_notify(prev_p, next_p);
219}
220
221/*
222 * Idle related variables and functions
223 */
224unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
225EXPORT_SYMBOL(boot_option_idle_override);
226
227static void (*x86_idle)(void);
228
229#ifndef CONFIG_SMP
230static inline void play_dead(void)
231{
232 BUG();
233}
234#endif
235
236void arch_cpu_idle_enter(void)
237{
238 tsc_verify_tsc_adjust(false);
239 local_touch_nmi();
240}
241
242void arch_cpu_idle_dead(void)
243{
244 play_dead();
245}
246
247/*
248 * Called from the generic idle code.
249 */
250void arch_cpu_idle(void)
251{
252 x86_idle();
253}
254
255/*
256 * We use this if we don't have any better idle routine..
257 */
258void __cpuidle default_idle(void)
259{
260 trace_cpu_idle_rcuidle(1, smp_processor_id());
261 safe_halt();
262 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
263}
264#ifdef CONFIG_APM_MODULE
265EXPORT_SYMBOL(default_idle);
266#endif
267
268#ifdef CONFIG_XEN
269bool xen_set_default_idle(void)
270{
271 bool ret = !!x86_idle;
272
273 x86_idle = default_idle;
274
275 return ret;
276}
277#endif
278void stop_this_cpu(void *dummy)
279{
280 local_irq_disable();
281 /*
282 * Remove this CPU:
283 */
284 set_cpu_online(smp_processor_id(), false);
285 disable_local_APIC();
286 mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
287
288 for (;;)
289 halt();
290}
291
292/*
293 * AMD Erratum 400 aware idle routine. We handle it the same way as C3 power
294 * states (local apic timer and TSC stop).
295 */
296static void amd_e400_idle(void)
297{
298 /*
299 * We cannot use static_cpu_has_bug() here because X86_BUG_AMD_APIC_C1E
300 * gets set after static_cpu_has() places have been converted via
301 * alternatives.
302 */
303 if (!boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) {
304 default_idle();
305 return;
306 }
307
308 tick_broadcast_enter();
309
310 default_idle();
311
312 /*
313 * The switch back from broadcast mode needs to be called with
314 * interrupts disabled.
315 */
316 local_irq_disable();
317 tick_broadcast_exit();
318 local_irq_enable();
319}
320
321/*
322 * Intel Core2 and older machines prefer MWAIT over HALT for C1.
323 * We can't rely on cpuidle installing MWAIT, because it will not load
324 * on systems that support only C1 -- so the boot default must be MWAIT.
325 *
326 * Some AMD machines are the opposite, they depend on using HALT.
327 *
328 * So for default C1, which is used during boot until cpuidle loads,
329 * use MWAIT-C1 on Intel HW that has it, else use HALT.
330 */
331static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
332{
333 if (c->x86_vendor != X86_VENDOR_INTEL)
334 return 0;
335
336 if (!cpu_has(c, X86_FEATURE_MWAIT) || static_cpu_has_bug(X86_BUG_MONITOR))
337 return 0;
338
339 return 1;
340}
341
342/*
343 * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT
344 * with interrupts enabled and no flags, which is backwards compatible with the
345 * original MWAIT implementation.
346 */
347static __cpuidle void mwait_idle(void)
348{
349 if (!current_set_polling_and_test()) {
350 trace_cpu_idle_rcuidle(1, smp_processor_id());
351 if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
352 mb(); /* quirk */
353 clflush((void *)¤t_thread_info()->flags);
354 mb(); /* quirk */
355 }
356
357 __monitor((void *)¤t_thread_info()->flags, 0, 0);
358 if (!need_resched())
359 __sti_mwait(0, 0);
360 else
361 local_irq_enable();
362 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
363 } else {
364 local_irq_enable();
365 }
366 __current_clr_polling();
367}
368
369void select_idle_routine(const struct cpuinfo_x86 *c)
370{
371#ifdef CONFIG_SMP
372 if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
373 pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
374#endif
375 if (x86_idle || boot_option_idle_override == IDLE_POLL)
376 return;
377
378 if (boot_cpu_has_bug(X86_BUG_AMD_E400)) {
379 pr_info("using AMD E400 aware idle routine\n");
380 x86_idle = amd_e400_idle;
381 } else if (prefer_mwait_c1_over_halt(c)) {
382 pr_info("using mwait in idle threads\n");
383 x86_idle = mwait_idle;
384 } else
385 x86_idle = default_idle;
386}
387
388void amd_e400_c1e_apic_setup(void)
389{
390 if (boot_cpu_has_bug(X86_BUG_AMD_APIC_C1E)) {
391 pr_info("Switch to broadcast mode on CPU%d\n", smp_processor_id());
392 local_irq_disable();
393 tick_broadcast_force();
394 local_irq_enable();
395 }
396}
397
398void __init arch_post_acpi_subsys_init(void)
399{
400 u32 lo, hi;
401
402 if (!boot_cpu_has_bug(X86_BUG_AMD_E400))
403 return;
404
405 /*
406 * AMD E400 detection needs to happen after ACPI has been enabled. If
407 * the machine is affected K8_INTP_C1E_ACTIVE_MASK bits are set in
408 * MSR_K8_INT_PENDING_MSG.
409 */
410 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
411 if (!(lo & K8_INTP_C1E_ACTIVE_MASK))
412 return;
413
414 boot_cpu_set_bug(X86_BUG_AMD_APIC_C1E);
415
416 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
417 mark_tsc_unstable("TSC halt in AMD C1E");
418 pr_info("System has AMD C1E enabled\n");
419}
420
421static int __init idle_setup(char *str)
422{
423 if (!str)
424 return -EINVAL;
425
426 if (!strcmp(str, "poll")) {
427 pr_info("using polling idle threads\n");
428 boot_option_idle_override = IDLE_POLL;
429 cpu_idle_poll_ctrl(true);
430 } else if (!strcmp(str, "halt")) {
431 /*
432 * When the boot option of idle=halt is added, halt is
433 * forced to be used for CPU idle. In such case CPU C2/C3
434 * won't be used again.
435 * To continue to load the CPU idle driver, don't touch
436 * the boot_option_idle_override.
437 */
438 x86_idle = default_idle;
439 boot_option_idle_override = IDLE_HALT;
440 } else if (!strcmp(str, "nomwait")) {
441 /*
442 * If the boot option of "idle=nomwait" is added,
443 * it means that mwait will be disabled for CPU C2/C3
444 * states. In such case it won't touch the variable
445 * of boot_option_idle_override.
446 */
447 boot_option_idle_override = IDLE_NOMWAIT;
448 } else
449 return -1;
450
451 return 0;
452}
453early_param("idle", idle_setup);
454
455unsigned long arch_align_stack(unsigned long sp)
456{
457 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
458 sp -= get_random_int() % 8192;
459 return sp & ~0xf;
460}
461
462unsigned long arch_randomize_brk(struct mm_struct *mm)
463{
464 return randomize_page(mm->brk, 0x02000000);
465}
466
467/*
468 * Return saved PC of a blocked thread.
469 * What is this good for? it will be always the scheduler or ret_from_fork.
470 */
471unsigned long thread_saved_pc(struct task_struct *tsk)
472{
473 struct inactive_task_frame *frame =
474 (struct inactive_task_frame *) READ_ONCE(tsk->thread.sp);
475 return READ_ONCE_NOCHECK(frame->ret_addr);
476}
477
478/*
479 * Called from fs/proc with a reference on @p to find the function
480 * which called into schedule(). This needs to be done carefully
481 * because the task might wake up and we might look at a stack
482 * changing under us.
483 */
484unsigned long get_wchan(struct task_struct *p)
485{
486 unsigned long start, bottom, top, sp, fp, ip, ret = 0;
487 int count = 0;
488
489 if (!p || p == current || p->state == TASK_RUNNING)
490 return 0;
491
492 if (!try_get_task_stack(p))
493 return 0;
494
495 start = (unsigned long)task_stack_page(p);
496 if (!start)
497 goto out;
498
499 /*
500 * Layout of the stack page:
501 *
502 * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)
503 * PADDING
504 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
505 * stack
506 * ----------- bottom = start
507 *
508 * The tasks stack pointer points at the location where the
509 * framepointer is stored. The data on the stack is:
510 * ... IP FP ... IP FP
511 *
512 * We need to read FP and IP, so we need to adjust the upper
513 * bound by another unsigned long.
514 */
515 top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;
516 top -= 2 * sizeof(unsigned long);
517 bottom = start;
518
519 sp = READ_ONCE(p->thread.sp);
520 if (sp < bottom || sp > top)
521 goto out;
522
523 fp = READ_ONCE_NOCHECK(((struct inactive_task_frame *)sp)->bp);
524 do {
525 if (fp < bottom || fp > top)
526 goto out;
527 ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
528 if (!in_sched_functions(ip)) {
529 ret = ip;
530 goto out;
531 }
532 fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
533 } while (count++ < 16 && p->state != TASK_RUNNING);
534
535out:
536 put_task_stack(p);
537 return ret;
538}
1#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
2
3#include <linux/errno.h>
4#include <linux/kernel.h>
5#include <linux/mm.h>
6#include <linux/smp.h>
7#include <linux/prctl.h>
8#include <linux/slab.h>
9#include <linux/sched.h>
10#include <linux/module.h>
11#include <linux/pm.h>
12#include <linux/tick.h>
13#include <linux/random.h>
14#include <linux/user-return-notifier.h>
15#include <linux/dmi.h>
16#include <linux/utsname.h>
17#include <linux/stackprotector.h>
18#include <linux/tick.h>
19#include <linux/cpuidle.h>
20#include <trace/events/power.h>
21#include <linux/hw_breakpoint.h>
22#include <asm/cpu.h>
23#include <asm/apic.h>
24#include <asm/syscalls.h>
25#include <asm/idle.h>
26#include <asm/uaccess.h>
27#include <asm/mwait.h>
28#include <asm/fpu/internal.h>
29#include <asm/debugreg.h>
30#include <asm/nmi.h>
31#include <asm/tlbflush.h>
32#include <asm/mce.h>
33#include <asm/vm86.h>
34
35/*
36 * per-CPU TSS segments. Threads are completely 'soft' on Linux,
37 * no more per-task TSS's. The TSS size is kept cacheline-aligned
38 * so they are allowed to end up in the .data..cacheline_aligned
39 * section. Since TSS's are completely CPU-local, we want them
40 * on exact cacheline boundaries, to eliminate cacheline ping-pong.
41 */
42__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
43 .x86_tss = {
44 .sp0 = TOP_OF_INIT_STACK,
45#ifdef CONFIG_X86_32
46 .ss0 = __KERNEL_DS,
47 .ss1 = __KERNEL_CS,
48 .io_bitmap_base = INVALID_IO_BITMAP_OFFSET,
49#endif
50 },
51#ifdef CONFIG_X86_32
52 /*
53 * Note that the .io_bitmap member must be extra-big. This is because
54 * the CPU will access an additional byte beyond the end of the IO
55 * permission bitmap. The extra byte must be all 1 bits, and must
56 * be within the limit.
57 */
58 .io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 },
59#endif
60#ifdef CONFIG_X86_32
61 .SYSENTER_stack_canary = STACK_END_MAGIC,
62#endif
63};
64EXPORT_PER_CPU_SYMBOL(cpu_tss);
65
66#ifdef CONFIG_X86_64
67static DEFINE_PER_CPU(unsigned char, is_idle);
68static ATOMIC_NOTIFIER_HEAD(idle_notifier);
69
70void idle_notifier_register(struct notifier_block *n)
71{
72 atomic_notifier_chain_register(&idle_notifier, n);
73}
74EXPORT_SYMBOL_GPL(idle_notifier_register);
75
76void idle_notifier_unregister(struct notifier_block *n)
77{
78 atomic_notifier_chain_unregister(&idle_notifier, n);
79}
80EXPORT_SYMBOL_GPL(idle_notifier_unregister);
81#endif
82
83/*
84 * this gets called so that we can store lazy state into memory and copy the
85 * current task into the new thread.
86 */
87int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
88{
89 memcpy(dst, src, arch_task_struct_size);
90#ifdef CONFIG_VM86
91 dst->thread.vm86 = NULL;
92#endif
93
94 return fpu__copy(&dst->thread.fpu, &src->thread.fpu);
95}
96
97/*
98 * Free current thread data structures etc..
99 */
100void exit_thread(void)
101{
102 struct task_struct *me = current;
103 struct thread_struct *t = &me->thread;
104 unsigned long *bp = t->io_bitmap_ptr;
105 struct fpu *fpu = &t->fpu;
106
107 if (bp) {
108 struct tss_struct *tss = &per_cpu(cpu_tss, get_cpu());
109
110 t->io_bitmap_ptr = NULL;
111 clear_thread_flag(TIF_IO_BITMAP);
112 /*
113 * Careful, clear this in the TSS too:
114 */
115 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
116 t->io_bitmap_max = 0;
117 put_cpu();
118 kfree(bp);
119 }
120
121 free_vm86(t);
122
123 fpu__drop(fpu);
124}
125
126void flush_thread(void)
127{
128 struct task_struct *tsk = current;
129
130 flush_ptrace_hw_breakpoint(tsk);
131 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
132
133 fpu__clear(&tsk->thread.fpu);
134}
135
136static void hard_disable_TSC(void)
137{
138 cr4_set_bits(X86_CR4_TSD);
139}
140
141void disable_TSC(void)
142{
143 preempt_disable();
144 if (!test_and_set_thread_flag(TIF_NOTSC))
145 /*
146 * Must flip the CPU state synchronously with
147 * TIF_NOTSC in the current running context.
148 */
149 hard_disable_TSC();
150 preempt_enable();
151}
152
153static void hard_enable_TSC(void)
154{
155 cr4_clear_bits(X86_CR4_TSD);
156}
157
158static void enable_TSC(void)
159{
160 preempt_disable();
161 if (test_and_clear_thread_flag(TIF_NOTSC))
162 /*
163 * Must flip the CPU state synchronously with
164 * TIF_NOTSC in the current running context.
165 */
166 hard_enable_TSC();
167 preempt_enable();
168}
169
170int get_tsc_mode(unsigned long adr)
171{
172 unsigned int val;
173
174 if (test_thread_flag(TIF_NOTSC))
175 val = PR_TSC_SIGSEGV;
176 else
177 val = PR_TSC_ENABLE;
178
179 return put_user(val, (unsigned int __user *)adr);
180}
181
182int set_tsc_mode(unsigned int val)
183{
184 if (val == PR_TSC_SIGSEGV)
185 disable_TSC();
186 else if (val == PR_TSC_ENABLE)
187 enable_TSC();
188 else
189 return -EINVAL;
190
191 return 0;
192}
193
194void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
195 struct tss_struct *tss)
196{
197 struct thread_struct *prev, *next;
198
199 prev = &prev_p->thread;
200 next = &next_p->thread;
201
202 if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
203 test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
204 unsigned long debugctl = get_debugctlmsr();
205
206 debugctl &= ~DEBUGCTLMSR_BTF;
207 if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
208 debugctl |= DEBUGCTLMSR_BTF;
209
210 update_debugctlmsr(debugctl);
211 }
212
213 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
214 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
215 /* prev and next are different */
216 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
217 hard_disable_TSC();
218 else
219 hard_enable_TSC();
220 }
221
222 if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
223 /*
224 * Copy the relevant range of the IO bitmap.
225 * Normally this is 128 bytes or less:
226 */
227 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
228 max(prev->io_bitmap_max, next->io_bitmap_max));
229 } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
230 /*
231 * Clear any possible leftover bits:
232 */
233 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
234 }
235 propagate_user_return_notify(prev_p, next_p);
236}
237
238/*
239 * Idle related variables and functions
240 */
241unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
242EXPORT_SYMBOL(boot_option_idle_override);
243
244static void (*x86_idle)(void);
245
246#ifndef CONFIG_SMP
247static inline void play_dead(void)
248{
249 BUG();
250}
251#endif
252
253#ifdef CONFIG_X86_64
254void enter_idle(void)
255{
256 this_cpu_write(is_idle, 1);
257 atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
258}
259
260static void __exit_idle(void)
261{
262 if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
263 return;
264 atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
265}
266
267/* Called from interrupts to signify idle end */
268void exit_idle(void)
269{
270 /* idle loop has pid 0 */
271 if (current->pid)
272 return;
273 __exit_idle();
274}
275#endif
276
277void arch_cpu_idle_enter(void)
278{
279 local_touch_nmi();
280 enter_idle();
281}
282
283void arch_cpu_idle_exit(void)
284{
285 __exit_idle();
286}
287
288void arch_cpu_idle_dead(void)
289{
290 play_dead();
291}
292
293/*
294 * Called from the generic idle code.
295 */
296void arch_cpu_idle(void)
297{
298 x86_idle();
299}
300
301/*
302 * We use this if we don't have any better idle routine..
303 */
304void default_idle(void)
305{
306 trace_cpu_idle_rcuidle(1, smp_processor_id());
307 safe_halt();
308 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
309}
310#ifdef CONFIG_APM_MODULE
311EXPORT_SYMBOL(default_idle);
312#endif
313
314#ifdef CONFIG_XEN
315bool xen_set_default_idle(void)
316{
317 bool ret = !!x86_idle;
318
319 x86_idle = default_idle;
320
321 return ret;
322}
323#endif
324void stop_this_cpu(void *dummy)
325{
326 local_irq_disable();
327 /*
328 * Remove this CPU:
329 */
330 set_cpu_online(smp_processor_id(), false);
331 disable_local_APIC();
332 mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
333
334 for (;;)
335 halt();
336}
337
338bool amd_e400_c1e_detected;
339EXPORT_SYMBOL(amd_e400_c1e_detected);
340
341static cpumask_var_t amd_e400_c1e_mask;
342
343void amd_e400_remove_cpu(int cpu)
344{
345 if (amd_e400_c1e_mask != NULL)
346 cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
347}
348
349/*
350 * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
351 * pending message MSR. If we detect C1E, then we handle it the same
352 * way as C3 power states (local apic timer and TSC stop)
353 */
354static void amd_e400_idle(void)
355{
356 if (!amd_e400_c1e_detected) {
357 u32 lo, hi;
358
359 rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
360
361 if (lo & K8_INTP_C1E_ACTIVE_MASK) {
362 amd_e400_c1e_detected = true;
363 if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
364 mark_tsc_unstable("TSC halt in AMD C1E");
365 pr_info("System has AMD C1E enabled\n");
366 }
367 }
368
369 if (amd_e400_c1e_detected) {
370 int cpu = smp_processor_id();
371
372 if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
373 cpumask_set_cpu(cpu, amd_e400_c1e_mask);
374 /* Force broadcast so ACPI can not interfere. */
375 tick_broadcast_force();
376 pr_info("Switch to broadcast mode on CPU%d\n", cpu);
377 }
378 tick_broadcast_enter();
379
380 default_idle();
381
382 /*
383 * The switch back from broadcast mode needs to be
384 * called with interrupts disabled.
385 */
386 local_irq_disable();
387 tick_broadcast_exit();
388 local_irq_enable();
389 } else
390 default_idle();
391}
392
393/*
394 * Intel Core2 and older machines prefer MWAIT over HALT for C1.
395 * We can't rely on cpuidle installing MWAIT, because it will not load
396 * on systems that support only C1 -- so the boot default must be MWAIT.
397 *
398 * Some AMD machines are the opposite, they depend on using HALT.
399 *
400 * So for default C1, which is used during boot until cpuidle loads,
401 * use MWAIT-C1 on Intel HW that has it, else use HALT.
402 */
403static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
404{
405 if (c->x86_vendor != X86_VENDOR_INTEL)
406 return 0;
407
408 if (!cpu_has(c, X86_FEATURE_MWAIT))
409 return 0;
410
411 return 1;
412}
413
414/*
415 * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT
416 * with interrupts enabled and no flags, which is backwards compatible with the
417 * original MWAIT implementation.
418 */
419static void mwait_idle(void)
420{
421 if (!current_set_polling_and_test()) {
422 trace_cpu_idle_rcuidle(1, smp_processor_id());
423 if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
424 mb(); /* quirk */
425 clflush((void *)¤t_thread_info()->flags);
426 mb(); /* quirk */
427 }
428
429 __monitor((void *)¤t_thread_info()->flags, 0, 0);
430 if (!need_resched())
431 __sti_mwait(0, 0);
432 else
433 local_irq_enable();
434 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
435 } else {
436 local_irq_enable();
437 }
438 __current_clr_polling();
439}
440
441void select_idle_routine(const struct cpuinfo_x86 *c)
442{
443#ifdef CONFIG_SMP
444 if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
445 pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
446#endif
447 if (x86_idle || boot_option_idle_override == IDLE_POLL)
448 return;
449
450 if (cpu_has_bug(c, X86_BUG_AMD_APIC_C1E)) {
451 /* E400: APIC timer interrupt does not wake up CPU from C1e */
452 pr_info("using AMD E400 aware idle routine\n");
453 x86_idle = amd_e400_idle;
454 } else if (prefer_mwait_c1_over_halt(c)) {
455 pr_info("using mwait in idle threads\n");
456 x86_idle = mwait_idle;
457 } else
458 x86_idle = default_idle;
459}
460
461void __init init_amd_e400_c1e_mask(void)
462{
463 /* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
464 if (x86_idle == amd_e400_idle)
465 zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
466}
467
468static int __init idle_setup(char *str)
469{
470 if (!str)
471 return -EINVAL;
472
473 if (!strcmp(str, "poll")) {
474 pr_info("using polling idle threads\n");
475 boot_option_idle_override = IDLE_POLL;
476 cpu_idle_poll_ctrl(true);
477 } else if (!strcmp(str, "halt")) {
478 /*
479 * When the boot option of idle=halt is added, halt is
480 * forced to be used for CPU idle. In such case CPU C2/C3
481 * won't be used again.
482 * To continue to load the CPU idle driver, don't touch
483 * the boot_option_idle_override.
484 */
485 x86_idle = default_idle;
486 boot_option_idle_override = IDLE_HALT;
487 } else if (!strcmp(str, "nomwait")) {
488 /*
489 * If the boot option of "idle=nomwait" is added,
490 * it means that mwait will be disabled for CPU C2/C3
491 * states. In such case it won't touch the variable
492 * of boot_option_idle_override.
493 */
494 boot_option_idle_override = IDLE_NOMWAIT;
495 } else
496 return -1;
497
498 return 0;
499}
500early_param("idle", idle_setup);
501
502unsigned long arch_align_stack(unsigned long sp)
503{
504 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
505 sp -= get_random_int() % 8192;
506 return sp & ~0xf;
507}
508
509unsigned long arch_randomize_brk(struct mm_struct *mm)
510{
511 unsigned long range_end = mm->brk + 0x02000000;
512 return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
513}
514
515/*
516 * Called from fs/proc with a reference on @p to find the function
517 * which called into schedule(). This needs to be done carefully
518 * because the task might wake up and we might look at a stack
519 * changing under us.
520 */
521unsigned long get_wchan(struct task_struct *p)
522{
523 unsigned long start, bottom, top, sp, fp, ip;
524 int count = 0;
525
526 if (!p || p == current || p->state == TASK_RUNNING)
527 return 0;
528
529 start = (unsigned long)task_stack_page(p);
530 if (!start)
531 return 0;
532
533 /*
534 * Layout of the stack page:
535 *
536 * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)
537 * PADDING
538 * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
539 * stack
540 * ----------- bottom = start + sizeof(thread_info)
541 * thread_info
542 * ----------- start
543 *
544 * The tasks stack pointer points at the location where the
545 * framepointer is stored. The data on the stack is:
546 * ... IP FP ... IP FP
547 *
548 * We need to read FP and IP, so we need to adjust the upper
549 * bound by another unsigned long.
550 */
551 top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;
552 top -= 2 * sizeof(unsigned long);
553 bottom = start + sizeof(struct thread_info);
554
555 sp = READ_ONCE(p->thread.sp);
556 if (sp < bottom || sp > top)
557 return 0;
558
559 fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
560 do {
561 if (fp < bottom || fp > top)
562 return 0;
563 ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
564 if (!in_sched_functions(ip))
565 return ip;
566 fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
567 } while (count++ < 16 && p->state != TASK_RUNNING);
568 return 0;
569}