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Commit | Line | Data |
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c767a54b JP |
1 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
2 | ||
61c4628b SS |
3 | #include <linux/errno.h> |
4 | #include <linux/kernel.h> | |
5 | #include <linux/mm.h> | |
6 | #include <linux/smp.h> | |
389d1fb1 | 7 | #include <linux/prctl.h> |
61c4628b SS |
8 | #include <linux/slab.h> |
9 | #include <linux/sched.h> | |
186f4360 PG |
10 | #include <linux/init.h> |
11 | #include <linux/export.h> | |
7f424a8b | 12 | #include <linux/pm.h> |
162a688e | 13 | #include <linux/tick.h> |
9d62dcdf | 14 | #include <linux/random.h> |
7c68af6e | 15 | #include <linux/user-return-notifier.h> |
814e2c84 AI |
16 | #include <linux/dmi.h> |
17 | #include <linux/utsname.h> | |
90e24014 RW |
18 | #include <linux/stackprotector.h> |
19 | #include <linux/tick.h> | |
20 | #include <linux/cpuidle.h> | |
61613521 | 21 | #include <trace/events/power.h> |
24f1e32c | 22 | #include <linux/hw_breakpoint.h> |
93789b32 | 23 | #include <asm/cpu.h> |
d3ec5cae | 24 | #include <asm/apic.h> |
2c1b284e | 25 | #include <asm/syscalls.h> |
389d1fb1 JF |
26 | #include <asm/idle.h> |
27 | #include <asm/uaccess.h> | |
b253149b | 28 | #include <asm/mwait.h> |
78f7f1e5 | 29 | #include <asm/fpu/internal.h> |
66cb5917 | 30 | #include <asm/debugreg.h> |
90e24014 | 31 | #include <asm/nmi.h> |
375074cc | 32 | #include <asm/tlbflush.h> |
8838eb6c | 33 | #include <asm/mce.h> |
9fda6a06 | 34 | #include <asm/vm86.h> |
90e24014 | 35 | |
45046892 TG |
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 | */ | |
d0a0de21 AL |
43 | __visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = { |
44 | .x86_tss = { | |
d9e05cc5 | 45 | .sp0 = TOP_OF_INIT_STACK, |
d0a0de21 AL |
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 | |
2a41aa4f AL |
61 | #ifdef CONFIG_X86_32 |
62 | .SYSENTER_stack_canary = STACK_END_MAGIC, | |
63 | #endif | |
d0a0de21 | 64 | }; |
de71ad2c | 65 | EXPORT_PER_CPU_SYMBOL(cpu_tss); |
45046892 | 66 | |
90e24014 RW |
67 | #ifdef CONFIG_X86_64 |
68 | static DEFINE_PER_CPU(unsigned char, is_idle); | |
69 | static ATOMIC_NOTIFIER_HEAD(idle_notifier); | |
70 | ||
71 | void idle_notifier_register(struct notifier_block *n) | |
72 | { | |
73 | atomic_notifier_chain_register(&idle_notifier, n); | |
74 | } | |
75 | EXPORT_SYMBOL_GPL(idle_notifier_register); | |
76 | ||
77 | void idle_notifier_unregister(struct notifier_block *n) | |
78 | { | |
79 | atomic_notifier_chain_unregister(&idle_notifier, n); | |
80 | } | |
81 | EXPORT_SYMBOL_GPL(idle_notifier_unregister); | |
82 | #endif | |
c1e3b377 | 83 | |
55ccf3fe SS |
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 | */ | |
61c4628b SS |
88 | int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) |
89 | { | |
5aaeb5c0 | 90 | memcpy(dst, src, arch_task_struct_size); |
2459ee86 AL |
91 | #ifdef CONFIG_VM86 |
92 | dst->thread.vm86 = NULL; | |
93 | #endif | |
f1853505 | 94 | |
c69e098b | 95 | return fpu__copy(&dst->thread.fpu, &src->thread.fpu); |
61c4628b | 96 | } |
7f424a8b | 97 | |
389d1fb1 JF |
98 | /* |
99 | * Free current thread data structures etc.. | |
100 | */ | |
e6464694 | 101 | void exit_thread(struct task_struct *tsk) |
389d1fb1 | 102 | { |
e6464694 | 103 | struct thread_struct *t = &tsk->thread; |
250981e6 | 104 | unsigned long *bp = t->io_bitmap_ptr; |
ca6787ba | 105 | struct fpu *fpu = &t->fpu; |
389d1fb1 | 106 | |
250981e6 | 107 | if (bp) { |
24933b82 | 108 | struct tss_struct *tss = &per_cpu(cpu_tss, get_cpu()); |
389d1fb1 | 109 | |
389d1fb1 JF |
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(); | |
250981e6 | 118 | kfree(bp); |
389d1fb1 | 119 | } |
1dcc8d7b | 120 | |
9fda6a06 BG |
121 | free_vm86(t); |
122 | ||
50338615 | 123 | fpu__drop(fpu); |
389d1fb1 JF |
124 | } |
125 | ||
126 | void flush_thread(void) | |
127 | { | |
128 | struct task_struct *tsk = current; | |
129 | ||
24f1e32c | 130 | flush_ptrace_hw_breakpoint(tsk); |
389d1fb1 | 131 | memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array)); |
110d7f75 | 132 | |
04c8e01d | 133 | fpu__clear(&tsk->thread.fpu); |
389d1fb1 JF |
134 | } |
135 | ||
136 | static void hard_disable_TSC(void) | |
137 | { | |
375074cc | 138 | cr4_set_bits(X86_CR4_TSD); |
389d1fb1 JF |
139 | } |
140 | ||
141 | void 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 | ||
153 | static void hard_enable_TSC(void) | |
154 | { | |
375074cc | 155 | cr4_clear_bits(X86_CR4_TSD); |
389d1fb1 JF |
156 | } |
157 | ||
158 | static 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 | ||
170 | int 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 | ||
182 | int 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 | ||
194 | void __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 | ||
ea8e61b7 PZ |
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 | } | |
389d1fb1 | 212 | |
389d1fb1 JF |
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 | } | |
7c68af6e | 235 | propagate_user_return_notify(prev_p, next_p); |
389d1fb1 JF |
236 | } |
237 | ||
00dba564 TG |
238 | /* |
239 | * Idle related variables and functions | |
240 | */ | |
d1896049 | 241 | unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE; |
00dba564 TG |
242 | EXPORT_SYMBOL(boot_option_idle_override); |
243 | ||
a476bda3 | 244 | static void (*x86_idle)(void); |
00dba564 | 245 | |
90e24014 RW |
246 | #ifndef CONFIG_SMP |
247 | static inline void play_dead(void) | |
248 | { | |
249 | BUG(); | |
250 | } | |
251 | #endif | |
252 | ||
253 | #ifdef CONFIG_X86_64 | |
254 | void enter_idle(void) | |
255 | { | |
c6ae41e7 | 256 | this_cpu_write(is_idle, 1); |
90e24014 RW |
257 | atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL); |
258 | } | |
259 | ||
260 | static 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 */ | |
268 | void exit_idle(void) | |
269 | { | |
270 | /* idle loop has pid 0 */ | |
271 | if (current->pid) | |
272 | return; | |
273 | __exit_idle(); | |
274 | } | |
275 | #endif | |
276 | ||
7d1a9417 TG |
277 | void arch_cpu_idle_enter(void) |
278 | { | |
279 | local_touch_nmi(); | |
280 | enter_idle(); | |
281 | } | |
90e24014 | 282 | |
7d1a9417 TG |
283 | void arch_cpu_idle_exit(void) |
284 | { | |
285 | __exit_idle(); | |
286 | } | |
90e24014 | 287 | |
7d1a9417 TG |
288 | void arch_cpu_idle_dead(void) |
289 | { | |
290 | play_dead(); | |
291 | } | |
90e24014 | 292 | |
7d1a9417 TG |
293 | /* |
294 | * Called from the generic idle code. | |
295 | */ | |
296 | void arch_cpu_idle(void) | |
297 | { | |
16f8b05a | 298 | x86_idle(); |
90e24014 RW |
299 | } |
300 | ||
00dba564 | 301 | /* |
7d1a9417 | 302 | * We use this if we don't have any better idle routine.. |
00dba564 TG |
303 | */ |
304 | void default_idle(void) | |
305 | { | |
4d0e42cc | 306 | trace_cpu_idle_rcuidle(1, smp_processor_id()); |
7d1a9417 | 307 | safe_halt(); |
4d0e42cc | 308 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); |
00dba564 | 309 | } |
60b8b1de | 310 | #ifdef CONFIG_APM_MODULE |
00dba564 TG |
311 | EXPORT_SYMBOL(default_idle); |
312 | #endif | |
313 | ||
6a377ddc LB |
314 | #ifdef CONFIG_XEN |
315 | bool xen_set_default_idle(void) | |
e5fd47bf | 316 | { |
a476bda3 | 317 | bool ret = !!x86_idle; |
e5fd47bf | 318 | |
a476bda3 | 319 | x86_idle = default_idle; |
e5fd47bf KRW |
320 | |
321 | return ret; | |
322 | } | |
6a377ddc | 323 | #endif |
d3ec5cae IV |
324 | void stop_this_cpu(void *dummy) |
325 | { | |
326 | local_irq_disable(); | |
327 | /* | |
328 | * Remove this CPU: | |
329 | */ | |
4f062896 | 330 | set_cpu_online(smp_processor_id(), false); |
d3ec5cae | 331 | disable_local_APIC(); |
8838eb6c | 332 | mcheck_cpu_clear(this_cpu_ptr(&cpu_info)); |
d3ec5cae | 333 | |
27be4570 LB |
334 | for (;;) |
335 | halt(); | |
7f424a8b PZ |
336 | } |
337 | ||
02c68a02 LB |
338 | bool amd_e400_c1e_detected; |
339 | EXPORT_SYMBOL(amd_e400_c1e_detected); | |
aa276e1c | 340 | |
02c68a02 | 341 | static cpumask_var_t amd_e400_c1e_mask; |
4faac97d | 342 | |
02c68a02 | 343 | void amd_e400_remove_cpu(int cpu) |
4faac97d | 344 | { |
02c68a02 LB |
345 | if (amd_e400_c1e_mask != NULL) |
346 | cpumask_clear_cpu(cpu, amd_e400_c1e_mask); | |
4faac97d TG |
347 | } |
348 | ||
aa276e1c | 349 | /* |
02c68a02 | 350 | * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt |
aa276e1c TG |
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 | */ | |
02c68a02 | 354 | static void amd_e400_idle(void) |
aa276e1c | 355 | { |
02c68a02 | 356 | if (!amd_e400_c1e_detected) { |
aa276e1c TG |
357 | u32 lo, hi; |
358 | ||
359 | rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi); | |
e8c534ec | 360 | |
aa276e1c | 361 | if (lo & K8_INTP_C1E_ACTIVE_MASK) { |
02c68a02 | 362 | amd_e400_c1e_detected = true; |
40fb1715 | 363 | if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) |
09bfeea1 | 364 | mark_tsc_unstable("TSC halt in AMD C1E"); |
c767a54b | 365 | pr_info("System has AMD C1E enabled\n"); |
aa276e1c TG |
366 | } |
367 | } | |
368 | ||
02c68a02 | 369 | if (amd_e400_c1e_detected) { |
aa276e1c TG |
370 | int cpu = smp_processor_id(); |
371 | ||
02c68a02 LB |
372 | if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) { |
373 | cpumask_set_cpu(cpu, amd_e400_c1e_mask); | |
162a688e TG |
374 | /* Force broadcast so ACPI can not interfere. */ |
375 | tick_broadcast_force(); | |
c767a54b | 376 | pr_info("Switch to broadcast mode on CPU%d\n", cpu); |
aa276e1c | 377 | } |
435c350e | 378 | tick_broadcast_enter(); |
0beefa20 | 379 | |
aa276e1c | 380 | default_idle(); |
0beefa20 TG |
381 | |
382 | /* | |
383 | * The switch back from broadcast mode needs to be | |
384 | * called with interrupts disabled. | |
385 | */ | |
ea811747 | 386 | local_irq_disable(); |
435c350e | 387 | tick_broadcast_exit(); |
ea811747 | 388 | local_irq_enable(); |
aa276e1c TG |
389 | } else |
390 | default_idle(); | |
391 | } | |
392 | ||
b253149b LB |
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 | */ | |
403 | static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c) | |
404 | { | |
405 | if (c->x86_vendor != X86_VENDOR_INTEL) | |
406 | return 0; | |
407 | ||
08e237fa | 408 | if (!cpu_has(c, X86_FEATURE_MWAIT) || static_cpu_has_bug(X86_BUG_MONITOR)) |
b253149b LB |
409 | return 0; |
410 | ||
411 | return 1; | |
412 | } | |
413 | ||
414 | /* | |
0fb0328d HR |
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. | |
b253149b | 418 | */ |
b253149b LB |
419 | static void mwait_idle(void) |
420 | { | |
f8e617f4 | 421 | if (!current_set_polling_and_test()) { |
e43d0189 | 422 | trace_cpu_idle_rcuidle(1, smp_processor_id()); |
f8e617f4 | 423 | if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) { |
ca59809f | 424 | mb(); /* quirk */ |
b253149b | 425 | clflush((void *)¤t_thread_info()->flags); |
ca59809f | 426 | mb(); /* quirk */ |
f8e617f4 | 427 | } |
b253149b LB |
428 | |
429 | __monitor((void *)¤t_thread_info()->flags, 0, 0); | |
b253149b LB |
430 | if (!need_resched()) |
431 | __sti_mwait(0, 0); | |
432 | else | |
433 | local_irq_enable(); | |
e43d0189 | 434 | trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); |
f8e617f4 | 435 | } else { |
b253149b | 436 | local_irq_enable(); |
f8e617f4 MG |
437 | } |
438 | __current_clr_polling(); | |
b253149b LB |
439 | } |
440 | ||
148f9bb8 | 441 | void select_idle_routine(const struct cpuinfo_x86 *c) |
7f424a8b | 442 | { |
3e5095d1 | 443 | #ifdef CONFIG_SMP |
7d1a9417 | 444 | if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1) |
c767a54b | 445 | pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n"); |
7f424a8b | 446 | #endif |
7d1a9417 | 447 | if (x86_idle || boot_option_idle_override == IDLE_POLL) |
6ddd2a27 TG |
448 | return; |
449 | ||
7d7dc116 | 450 | if (cpu_has_bug(c, X86_BUG_AMD_APIC_C1E)) { |
9d8888c2 | 451 | /* E400: APIC timer interrupt does not wake up CPU from C1e */ |
c767a54b | 452 | pr_info("using AMD E400 aware idle routine\n"); |
a476bda3 | 453 | x86_idle = amd_e400_idle; |
b253149b LB |
454 | } else if (prefer_mwait_c1_over_halt(c)) { |
455 | pr_info("using mwait in idle threads\n"); | |
456 | x86_idle = mwait_idle; | |
6ddd2a27 | 457 | } else |
a476bda3 | 458 | x86_idle = default_idle; |
7f424a8b PZ |
459 | } |
460 | ||
02c68a02 | 461 | void __init init_amd_e400_c1e_mask(void) |
30e1e6d1 | 462 | { |
02c68a02 | 463 | /* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */ |
a476bda3 | 464 | if (x86_idle == amd_e400_idle) |
02c68a02 | 465 | zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL); |
30e1e6d1 RR |
466 | } |
467 | ||
7f424a8b PZ |
468 | static int __init idle_setup(char *str) |
469 | { | |
ab6bc3e3 CG |
470 | if (!str) |
471 | return -EINVAL; | |
472 | ||
7f424a8b | 473 | if (!strcmp(str, "poll")) { |
c767a54b | 474 | pr_info("using polling idle threads\n"); |
d1896049 | 475 | boot_option_idle_override = IDLE_POLL; |
7d1a9417 | 476 | cpu_idle_poll_ctrl(true); |
d1896049 | 477 | } else if (!strcmp(str, "halt")) { |
c1e3b377 ZY |
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 | */ | |
a476bda3 | 485 | x86_idle = default_idle; |
d1896049 | 486 | boot_option_idle_override = IDLE_HALT; |
da5e09a1 ZY |
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 | */ | |
d1896049 | 494 | boot_option_idle_override = IDLE_NOMWAIT; |
c1e3b377 | 495 | } else |
7f424a8b PZ |
496 | return -1; |
497 | ||
7f424a8b PZ |
498 | return 0; |
499 | } | |
500 | early_param("idle", idle_setup); | |
501 | ||
9d62dcdf AW |
502 | unsigned 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 | ||
509 | unsigned 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 | ||
7ba78053 TG |
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 | */ | |
521 | unsigned 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 | ||
f7d27c35 | 559 | fp = READ_ONCE_NOCHECK(*(unsigned long *)sp); |
7ba78053 TG |
560 | do { |
561 | if (fp < bottom || fp > top) | |
562 | return 0; | |
f7d27c35 | 563 | ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long))); |
7ba78053 TG |
564 | if (!in_sched_functions(ip)) |
565 | return ip; | |
f7d27c35 | 566 | fp = READ_ONCE_NOCHECK(*(unsigned long *)fp); |
7ba78053 TG |
567 | } while (count++ < 16 && p->state != TASK_RUNNING); |
568 | return 0; | |
569 | } |