/arch/x86/kernel/process.c

  1#include <linux/errno.h>
  2#include <linux/kernel.h>
  3#include <linux/mm.h>
  4#include <linux/smp.h>
  5#include <linux/prctl.h>
  6#include <linux/slab.h>
  7#include <linux/sched.h>
  8#include <linux/module.h>
  9#include <linux/pm.h>
 10#include <linux/clockchips.h>
 11#include <linux/random.h>
 12#include <linux/user-return-notifier.h>
 13#include <linux/dmi.h>
 14#include <linux/utsname.h>
 15#include <trace/events/power.h>
 16#include <linux/hw_breakpoint.h>
 17#include <asm/cpu.h>
 18#include <asm/system.h>
 19#include <asm/apic.h>
 20#include <asm/syscalls.h>
 21#include <asm/idle.h>
 22#include <asm/uaccess.h>
 23#include <asm/i387.h>
 24#include <asm/debugreg.h>
 25
 26struct kmem_cache *task_xstate_cachep;
 27EXPORT_SYMBOL_GPL(task_xstate_cachep);
 28
 29int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 30{
 31	int ret;
 32
 33	*dst = *src;
 34	if (fpu_allocated(&src->thread.fpu)) {
 35		memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
 36		ret = fpu_alloc(&dst->thread.fpu);
 37		if (ret)
 38			return ret;
 39		fpu_copy(&dst->thread.fpu, &src->thread.fpu);
 40	}
 41	return 0;
 42}
 43
 44void free_thread_xstate(struct task_struct *tsk)
 45{
 46	fpu_free(&tsk->thread.fpu);
 47}
 48
 49void free_thread_info(struct thread_info *ti)
 50{
 51	free_thread_xstate(ti->task);
 52	free_pages((unsigned long)ti, get_order(THREAD_SIZE));
 53}
 54
 55void arch_task_cache_init(void)
 56{
 57        task_xstate_cachep =
 58        	kmem_cache_create("task_xstate", xstate_size,
 59				  __alignof__(union thread_xstate),
 60				  SLAB_PANIC | SLAB_NOTRACK, NULL);
 61}
 62
 63/*
 64 * Free current thread data structures etc..
 65 */
 66void exit_thread(void)
 67{
 68	struct task_struct *me = current;
 69	struct thread_struct *t = &me->thread;
 70	unsigned long *bp = t->io_bitmap_ptr;
 71
 72	if (bp) {
 73		struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
 74
 75		t->io_bitmap_ptr = NULL;
 76		clear_thread_flag(TIF_IO_BITMAP);
 77		/*
 78		 * Careful, clear this in the TSS too:
 79		 */
 80		memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
 81		t->io_bitmap_max = 0;
 82		put_cpu();
 83		kfree(bp);
 84	}
 85}
 86
 87void show_regs(struct pt_regs *regs)
 88{
 89	show_registers(regs);
 90	show_trace(NULL, regs, (unsigned long *)kernel_stack_pointer(regs), 0);
 91}
 92
 93void show_regs_common(void)
 94{
 95	const char *vendor, *product, *board;
 96
 97	vendor = dmi_get_system_info(DMI_SYS_VENDOR);
 98	if (!vendor)
 99		vendor = "";
100	product = dmi_get_system_info(DMI_PRODUCT_NAME);
101	if (!product)
102		product = "";
103
104	/* Board Name is optional */
105	board = dmi_get_system_info(DMI_BOARD_NAME);
106
107	printk(KERN_CONT "\n");
108	printk(KERN_DEFAULT "Pid: %d, comm: %.20s %s %s %.*s",
109		current->pid, current->comm, print_tainted(),
110		init_utsname()->release,
111		(int)strcspn(init_utsname()->version, " "),
112		init_utsname()->version);
113	printk(KERN_CONT " %s %s", vendor, product);
114	if (board)
115		printk(KERN_CONT "/%s", board);
116	printk(KERN_CONT "\n");
117}
118
119void flush_thread(void)
120{
121	struct task_struct *tsk = current;
122
123	flush_ptrace_hw_breakpoint(tsk);
124	memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
125	/*
126	 * Forget coprocessor state..
127	 */
128	tsk->fpu_counter = 0;
129	clear_fpu(tsk);
130	clear_used_math();
131}
132
133static void hard_disable_TSC(void)
134{
135	write_cr4(read_cr4() | X86_CR4_TSD);
136}
137
138void disable_TSC(void)
139{
140	preempt_disable();
141	if (!test_and_set_thread_flag(TIF_NOTSC))
142		/*
143		 * Must flip the CPU state synchronously with
144		 * TIF_NOTSC in the current running context.
145		 */
146		hard_disable_TSC();
147	preempt_enable();
148}
149
150static void hard_enable_TSC(void)
151{
152	write_cr4(read_cr4() & ~X86_CR4_TSD);
153}
154
155static void enable_TSC(void)
156{
157	preempt_disable();
158	if (test_and_clear_thread_flag(TIF_NOTSC))
159		/*
160		 * Must flip the CPU state synchronously with
161		 * TIF_NOTSC in the current running context.
162		 */
163		hard_enable_TSC();
164	preempt_enable();
165}
166
167int get_tsc_mode(unsigned long adr)
168{
169	unsigned int val;
170
171	if (test_thread_flag(TIF_NOTSC))
172		val = PR_TSC_SIGSEGV;
173	else
174		val = PR_TSC_ENABLE;
175
176	return put_user(val, (unsigned int __user *)adr);
177}
178
179int set_tsc_mode(unsigned int val)
180{
181	if (val == PR_TSC_SIGSEGV)
182		disable_TSC();
183	else if (val == PR_TSC_ENABLE)
184		enable_TSC();
185	else
186		return -EINVAL;
187
188	return 0;
189}
190
191void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
192		      struct tss_struct *tss)
193{
194	struct thread_struct *prev, *next;
195
196	prev = &prev_p->thread;
197	next = &next_p->thread;
198
199	if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
200	    test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
201		unsigned long debugctl = get_debugctlmsr();
202
203		debugctl &= ~DEBUGCTLMSR_BTF;
204		if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
205			debugctl |= DEBUGCTLMSR_BTF;
206
207		update_debugctlmsr(debugctl);
208	}
209
210	if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
211	    test_tsk_thread_flag(next_p, TIF_NOTSC)) {
212		/* prev and next are different */
213		if (test_tsk_thread_flag(next_p, TIF_NOTSC))
214			hard_disable_TSC();
215		else
216			hard_enable_TSC();
217	}
218
219	if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
220		/*
221		 * Copy the relevant range of the IO bitmap.
222		 * Normally this is 128 bytes or less:
223		 */
224		memcpy(tss->io_bitmap, next->io_bitmap_ptr,
225		       max(prev->io_bitmap_max, next->io_bitmap_max));
226	} else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
227		/*
228		 * Clear any possible leftover bits:
229		 */
230		memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
231	}
232	propagate_user_return_notify(prev_p, next_p);
233}
234
235int sys_fork(struct pt_regs *regs)
236{
237	return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
238}
239
240/*
241 * This is trivial, and on the face of it looks like it
242 * could equally well be done in user mode.
243 *
244 * Not so, for quite unobvious reasons - register pressure.
245 * In user mode vfork() cannot have a stack frame, and if
246 * done by calling the "clone()" system call directly, you
247 * do not have enough call-clobbered registers to hold all
248 * the information you need.
249 */
250int sys_vfork(struct pt_regs *regs)
251{
252	return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
253		       NULL, NULL);
254}
255
256long
257sys_clone(unsigned long clone_flags, unsigned long newsp,
258	  void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
259{
260	if (!newsp)
261		newsp = regs->sp;
262	return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
263}
264
265/*
266 * This gets run with %si containing the
267 * function to call, and %di containing
268 * the "args".
269 */
270extern void kernel_thread_helper(void);
271
272/*
273 * Create a kernel thread
274 */
275int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
276{
277	struct pt_regs regs;
278
279	memset(&regs, 0, sizeof(regs));
280
281	regs.si = (unsigned long) fn;
282	regs.di = (unsigned long) arg;
283
284#ifdef CONFIG_X86_32
285	regs.ds = __USER_DS;
286	regs.es = __USER_DS;
287	regs.fs = __KERNEL_PERCPU;
288	regs.gs = __KERNEL_STACK_CANARY;
289#else
290	regs.ss = __KERNEL_DS;
291#endif
292
293	regs.orig_ax = -1;
294	regs.ip = (unsigned long) kernel_thread_helper;
295	regs.cs = __KERNEL_CS | get_kernel_rpl();
296	regs.flags = X86_EFLAGS_IF | 0x2;
297
298	/* Ok, create the new process.. */
299	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
300}
301EXPORT_SYMBOL(kernel_thread);
302
303/*
304 * sys_execve() executes a new program.
305 */
306long sys_execve(const char __user *name,
307		const char __user *const __user *argv,
308		const char __user *const __user *envp, struct pt_regs *regs)
309{
310	long error;
311	char *filename;
312
313	filename = getname(name);
314	error = PTR_ERR(filename);
315	if (IS_ERR(filename))
316		return error;
317	error = do_execve(filename, argv, envp, regs);
318
319#ifdef CONFIG_X86_32
320	if (error == 0) {
321		/* Make sure we don't return using sysenter.. */
322                set_thread_flag(TIF_IRET);
323        }
324#endif
325
326	putname(filename);
327	return error;
328}
329
330/*
331 * Idle related variables and functions
332 */
333unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
334EXPORT_SYMBOL(boot_option_idle_override);
335
336/*
337 * Powermanagement idle function, if any..
338 */
339void (*pm_idle)(void);
340#ifdef CONFIG_APM_MODULE
341EXPORT_SYMBOL(pm_idle);
342#endif
343
344static inline int hlt_use_halt(void)
345{
346	return 1;
347}
348
349/*
350 * We use this if we don't have any better
351 * idle routine..
352 */
353void default_idle(void)
354{
355	if (hlt_use_halt()) {
356		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
357		trace_cpu_idle(1, smp_processor_id());
358		current_thread_info()->status &= ~TS_POLLING;
359		/*
360		 * TS_POLLING-cleared state must be visible before we
361		 * test NEED_RESCHED:
362		 */
363		smp_mb();
364
365		if (!need_resched())
366			safe_halt();	/* enables interrupts racelessly */
367		else
368			local_irq_enable();
369		current_thread_info()->status |= TS_POLLING;
370		trace_power_end(smp_processor_id());
371		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
372	} else {
373		local_irq_enable();
374		/* loop is done by the caller */
375		cpu_relax();
376	}
377}
378#ifdef CONFIG_APM_MODULE
379EXPORT_SYMBOL(default_idle);
380#endif
381
382void stop_this_cpu(void *dummy)
383{
384	local_irq_disable();
385	/*
386	 * Remove this CPU:
387	 */
388	set_cpu_online(smp_processor_id(), false);
389	disable_local_APIC();
390
391	for (;;) {
392		if (hlt_works(smp_processor_id()))
393			halt();
394	}
395}
396
397static void do_nothing(void *unused)
398{
399}
400
401/*
402 * cpu_idle_wait - Used to ensure that all the CPUs discard old value of
403 * pm_idle and update to new pm_idle value. Required while changing pm_idle
404 * handler on SMP systems.
405 *
406 * Caller must have changed pm_idle to the new value before the call. Old
407 * pm_idle value will not be used by any CPU after the return of this function.
408 */
409void cpu_idle_wait(void)
410{
411	smp_mb();
412	/* kick all the CPUs so that they exit out of pm_idle */
413	smp_call_function(do_nothing, NULL, 1);
414}
415EXPORT_SYMBOL_GPL(cpu_idle_wait);
416
417/*
418 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
419 * which can obviate IPI to trigger checking of need_resched.
420 * We execute MONITOR against need_resched and enter optimized wait state
421 * through MWAIT. Whenever someone changes need_resched, we would be woken
422 * up from MWAIT (without an IPI).
423 *
424 * New with Core Duo processors, MWAIT can take some hints based on CPU
425 * capability.
426 */
427void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
428{
429	if (!need_resched()) {
430		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
431			clflush((void *)&current_thread_info()->flags);
432
433		__monitor((void *)&current_thread_info()->flags, 0, 0);
434		smp_mb();
435		if (!need_resched())
436			__mwait(ax, cx);
437	}
438}
439
440/* Default MONITOR/MWAIT with no hints, used for default C1 state */
441static void mwait_idle(void)
442{
443	if (!need_resched()) {
444		trace_power_start(POWER_CSTATE, 1, smp_processor_id());
445		trace_cpu_idle(1, smp_processor_id());
446		if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
447			clflush((void *)&current_thread_info()->flags);
448
449		__monitor((void *)&current_thread_info()->flags, 0, 0);
450		smp_mb();
451		if (!need_resched())
452			__sti_mwait(0, 0);
453		else
454			local_irq_enable();
455		trace_power_end(smp_processor_id());
456		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
457	} else
458		local_irq_enable();
459}
460
461/*
462 * On SMP it's slightly faster (but much more power-consuming!)
463 * to poll the ->work.need_resched flag instead of waiting for the
464 * cross-CPU IPI to arrive. Use this option with caution.
465 */
466static void poll_idle(void)
467{
468	trace_power_start(POWER_CSTATE, 0, smp_processor_id());
469	trace_cpu_idle(0, smp_processor_id());
470	local_irq_enable();
471	while (!need_resched())
472		cpu_relax();
473	trace_power_end(smp_processor_id());
474	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
475}
476
477/*
478 * mwait selection logic:
479 *
480 * It depends on the CPU. For AMD CPUs that support MWAIT this is
481 * wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
482 * then depend on a clock divisor and current Pstate of the core. If
483 * all cores of a processor are in halt state (C1) the processor can
484 * enter the C1E (C1 enhanced) state. If mwait is used this will never
485 * happen.
486 *
487 * idle=mwait overrides this decision and forces the usage of mwait.
488 */
489
490#define MWAIT_INFO			0x05
491#define MWAIT_ECX_EXTENDED_INFO		0x01
492#define MWAIT_EDX_C1			0xf0
493
494int mwait_usable(const struct cpuinfo_x86 *c)
495{
496	u32 eax, ebx, ecx, edx;
497
498	if (boot_option_idle_override == IDLE_FORCE_MWAIT)
499		return 1;
500
501	if (c->cpuid_level < MWAIT_INFO)
502		return 0;
503
504	cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
505	/* Check, whether EDX has extended info about MWAIT */
506	if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
507		return 1;
508
509	/*
510	 * edx enumeratios MONITOR/MWAIT extensions. Check, whether
511	 * C1  supports MWAIT
512	 */
513	return (edx & MWAIT_EDX_C1);
514}
515
516bool amd_e400_c1e_detected;
517EXPORT_SYMBOL(amd_e400_c1e_detected);
518
519static cpumask_var_t amd_e400_c1e_mask;
520
521void amd_e400_remove_cpu(int cpu)
522{
523	if (amd_e400_c1e_mask != NULL)
524		cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
525}
526
527/*
528 * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
529 * pending message MSR. If we detect C1E, then we handle it the same
530 * way as C3 power states (local apic timer and TSC stop)
531 */
532static void amd_e400_idle(void)
533{
534	if (need_resched())
535		return;
536
537	if (!amd_e400_c1e_detected) {
538		u32 lo, hi;
539
540		rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
541
542		if (lo & K8_INTP_C1E_ACTIVE_MASK) {
543			amd_e400_c1e_detected = true;
544			if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
545				mark_tsc_unstable("TSC halt in AMD C1E");
546			printk(KERN_INFO "System has AMD C1E enabled\n");
547		}
548	}
549
550	if (amd_e400_c1e_detected) {
551		int cpu = smp_processor_id();
552
553		if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
554			cpumask_set_cpu(cpu, amd_e400_c1e_mask);
555			/*
556			 * Force broadcast so ACPI can not interfere.
557			 */
558			clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
559					   &cpu);
560			printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
561			       cpu);
562		}
563		clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
564
565		default_idle();
566
567		/*
568		 * The switch back from broadcast mode needs to be
569		 * called with interrupts disabled.
570		 */
571		 local_irq_disable();
572		 clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
573		 local_irq_enable();
574	} else
575		default_idle();
576}
577
578void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
579{
580#ifdef CONFIG_SMP
581	if (pm_idle == poll_idle && smp_num_siblings > 1) {
582		printk_once(KERN_WARNING "WARNING: polling idle and HT enabled,"
583			" performance may degrade.\n");
584	}
585#endif
586	if (pm_idle)
587		return;
588
589	if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
590		/*
591		 * One CPU supports mwait => All CPUs supports mwait
592		 */
593		printk(KERN_INFO "using mwait in idle threads.\n");
594		pm_idle = mwait_idle;
595	} else if (cpu_has_amd_erratum(amd_erratum_400)) {
596		/* E400: APIC timer interrupt does not wake up CPU from C1e */
597		printk(KERN_INFO "using AMD E400 aware idle routine\n");
598		pm_idle = amd_e400_idle;
599	} else
600		pm_idle = default_idle;
601}
602
603void __init init_amd_e400_c1e_mask(void)
604{
605	/* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
606	if (pm_idle == amd_e400_idle)
607		zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
608}
609
610static int __init idle_setup(char *str)
611{
612	if (!str)
613		return -EINVAL;
614
615	if (!strcmp(str, "poll")) {
616		printk("using polling idle threads.\n");
617		pm_idle = poll_idle;
618		boot_option_idle_override = IDLE_POLL;
619	} else if (!strcmp(str, "mwait")) {
620		boot_option_idle_override = IDLE_FORCE_MWAIT;
621		WARN_ONCE(1, "\"idle=mwait\" will be removed in 2012\n");
622	} else if (!strcmp(str, "halt")) {
623		/*
624		 * When the boot option of idle=halt is added, halt is
625		 * forced to be used for CPU idle. In such case CPU C2/C3
626		 * won't be used again.
627		 * To continue to load the CPU idle driver, don't touch
628		 * the boot_option_idle_override.
629		 */
630		pm_idle = default_idle;
631		boot_option_idle_override = IDLE_HALT;
632	} else if (!strcmp(str, "nomwait")) {
633		/*
634		 * If the boot option of "idle=nomwait" is added,
635		 * it means that mwait will be disabled for CPU C2/C3
636		 * states. In such case it won't touch the variable
637		 * of boot_option_idle_override.
638		 */
639		boot_option_idle_override = IDLE_NOMWAIT;
640	} else
641		return -1;
642
643	return 0;
644}
645early_param("idle", idle_setup);
646
647unsigned long arch_align_stack(unsigned long sp)
648{
649	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
650		sp -= get_random_int() % 8192;
651	return sp & ~0xf;
652}
653
654unsigned long arch_randomize_brk(struct mm_struct *mm)
655{
656	unsigned long range_end = mm->brk + 0x02000000;
657	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
658}
659