2 * linux/arch/x86-64/kernel/process.c
4 * Copyright (C) 1995 Linus Torvalds
6 * Pentium III FXSR, SSE support
7 * Gareth Hughes <gareth@valinux.com>, May 2000
12 * CPU hotplug support - ashok.raj@intel.com
13 * $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
17 * This file handles the architecture-dependent parts of process handling..
22 #include <linux/cpu.h>
23 #include <linux/errno.h>
24 #include <linux/sched.h>
25 #include <linux/kernel.h>
27 #include <linux/elfcore.h>
28 #include <linux/smp.h>
29 #include <linux/slab.h>
30 #include <linux/user.h>
31 #include <linux/module.h>
32 #include <linux/a.out.h>
33 #include <linux/interrupt.h>
34 #include <linux/delay.h>
35 #include <linux/ptrace.h>
36 #include <linux/utsname.h>
37 #include <linux/random.h>
38 #include <linux/notifier.h>
39 #include <linux/kprobes.h>
41 #include <asm/uaccess.h>
42 #include <asm/pgtable.h>
43 #include <asm/system.h>
45 #include <asm/processor.h>
47 #include <asm/mmu_context.h>
49 #include <asm/prctl.h>
50 #include <asm/kdebug.h>
52 #include <asm/proto.h>
56 asmlinkage extern void ret_from_fork(void);
58 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
60 unsigned long boot_option_idle_override = 0;
61 EXPORT_SYMBOL(boot_option_idle_override);
64 * Powermanagement idle function, if any..
66 void (*pm_idle)(void);
67 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
69 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
71 void idle_notifier_register(struct notifier_block *n)
73 atomic_notifier_chain_register(&idle_notifier, n);
75 EXPORT_SYMBOL_GPL(idle_notifier_register);
77 void idle_notifier_unregister(struct notifier_block *n)
79 atomic_notifier_chain_unregister(&idle_notifier, n);
81 EXPORT_SYMBOL(idle_notifier_unregister);
83 enum idle_state { CPU_IDLE, CPU_NOT_IDLE };
84 static DEFINE_PER_CPU(enum idle_state, idle_state) = CPU_NOT_IDLE;
88 __get_cpu_var(idle_state) = CPU_IDLE;
89 atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
92 static void __exit_idle(void)
94 __get_cpu_var(idle_state) = CPU_NOT_IDLE;
95 atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
98 /* Called from interrupts to signify idle end */
101 if (current->pid | read_pda(irqcount))
107 * We use this if we don't have any better
110 static void default_idle(void)
114 clear_thread_flag(TIF_POLLING_NRFLAG);
115 smp_mb__after_clear_bit();
116 while (!need_resched()) {
123 set_thread_flag(TIF_POLLING_NRFLAG);
127 * On SMP it's slightly faster (but much more power-consuming!)
128 * to poll the ->need_resched flag instead of waiting for the
129 * cross-CPU IPI to arrive. Use this option with caution.
131 static void poll_idle (void)
141 "i" (_TIF_NEED_RESCHED),
142 "m" (current_thread_info()->flags));
145 void cpu_idle_wait(void)
147 unsigned int cpu, this_cpu = get_cpu();
150 set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
154 for_each_online_cpu(cpu) {
155 per_cpu(cpu_idle_state, cpu) = 1;
159 __get_cpu_var(cpu_idle_state) = 0;
164 for_each_online_cpu(cpu) {
165 if (cpu_isset(cpu, map) &&
166 !per_cpu(cpu_idle_state, cpu))
169 cpus_and(map, map, cpu_online_map);
170 } while (!cpus_empty(map));
172 EXPORT_SYMBOL_GPL(cpu_idle_wait);
174 #ifdef CONFIG_HOTPLUG_CPU
175 DECLARE_PER_CPU(int, cpu_state);
178 /* We halt the CPU with physical CPU hotplug */
179 static inline void play_dead(void)
185 __get_cpu_var(cpu_state) = CPU_DEAD;
192 static inline void play_dead(void)
196 #endif /* CONFIG_HOTPLUG_CPU */
199 * The idle thread. There's no useful work to be
200 * done, so just try to conserve power and have a
201 * low exit latency (ie sit in a loop waiting for
202 * somebody to say that they'd like to reschedule)
206 set_thread_flag(TIF_POLLING_NRFLAG);
208 /* endless idle loop with no priority at all */
210 while (!need_resched()) {
213 if (__get_cpu_var(cpu_idle_state))
214 __get_cpu_var(cpu_idle_state) = 0;
220 if (cpu_is_offline(smp_processor_id()))
227 preempt_enable_no_resched();
234 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
235 * which can obviate IPI to trigger checking of need_resched.
236 * We execute MONITOR against need_resched and enter optimized wait state
237 * through MWAIT. Whenever someone changes need_resched, we would be woken
238 * up from MWAIT (without an IPI).
240 static void mwait_idle(void)
244 while (!need_resched()) {
245 __monitor((void *)¤t_thread_info()->flags, 0, 0);
253 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
256 if (cpu_has(c, X86_FEATURE_MWAIT)) {
258 * Skip, if setup has overridden idle.
259 * One CPU supports mwait => All CPUs supports mwait
263 printk("using mwait in idle threads.\n");
266 pm_idle = mwait_idle;
271 static int __init idle_setup (char *str)
273 if (!strncmp(str, "poll", 4)) {
274 printk("using polling idle threads.\n");
278 boot_option_idle_override = 1;
282 __setup("idle=", idle_setup);
284 /* Prints also some state that isn't saved in the pt_regs */
285 void __show_regs(struct pt_regs * regs)
287 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
288 unsigned int fsindex,gsindex;
289 unsigned int ds,cs,es;
293 printk("Pid: %d, comm: %.20s %s %s %.*s\n",
294 current->pid, current->comm, print_tainted(),
295 system_utsname.release,
296 (int)strcspn(system_utsname.version, " "),
297 system_utsname.version);
298 printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
299 printk_address(regs->rip);
300 printk("\nRSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss, regs->rsp,
302 printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
303 regs->rax, regs->rbx, regs->rcx);
304 printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
305 regs->rdx, regs->rsi, regs->rdi);
306 printk("RBP: %016lx R08: %016lx R09: %016lx\n",
307 regs->rbp, regs->r8, regs->r9);
308 printk("R10: %016lx R11: %016lx R12: %016lx\n",
309 regs->r10, regs->r11, regs->r12);
310 printk("R13: %016lx R14: %016lx R15: %016lx\n",
311 regs->r13, regs->r14, regs->r15);
313 asm("movl %%ds,%0" : "=r" (ds));
314 asm("movl %%cs,%0" : "=r" (cs));
315 asm("movl %%es,%0" : "=r" (es));
316 asm("movl %%fs,%0" : "=r" (fsindex));
317 asm("movl %%gs,%0" : "=r" (gsindex));
319 rdmsrl(MSR_FS_BASE, fs);
320 rdmsrl(MSR_GS_BASE, gs);
321 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
323 asm("movq %%cr0, %0": "=r" (cr0));
324 asm("movq %%cr2, %0": "=r" (cr2));
325 asm("movq %%cr3, %0": "=r" (cr3));
326 asm("movq %%cr4, %0": "=r" (cr4));
328 printk("FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
329 fs,fsindex,gs,gsindex,shadowgs);
330 printk("CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0);
331 printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
334 void show_regs(struct pt_regs *regs)
336 printk("CPU %d:", smp_processor_id());
338 show_trace(®s->rsp);
342 * Free current thread data structures etc..
344 void exit_thread(void)
346 struct task_struct *me = current;
347 struct thread_struct *t = &me->thread;
349 if (me->thread.io_bitmap_ptr) {
350 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
352 kfree(t->io_bitmap_ptr);
353 t->io_bitmap_ptr = NULL;
355 * Careful, clear this in the TSS too:
357 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
358 t->io_bitmap_max = 0;
363 void flush_thread(void)
365 struct task_struct *tsk = current;
366 struct thread_info *t = current_thread_info();
368 if (t->flags & _TIF_ABI_PENDING)
369 t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32);
371 tsk->thread.debugreg0 = 0;
372 tsk->thread.debugreg1 = 0;
373 tsk->thread.debugreg2 = 0;
374 tsk->thread.debugreg3 = 0;
375 tsk->thread.debugreg6 = 0;
376 tsk->thread.debugreg7 = 0;
377 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
379 * Forget coprocessor state..
385 void release_thread(struct task_struct *dead_task)
388 if (dead_task->mm->context.size) {
389 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
391 dead_task->mm->context.ldt,
392 dead_task->mm->context.size);
398 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
400 struct user_desc ud = {
407 struct n_desc_struct *desc = (void *)t->thread.tls_array;
409 desc->a = LDT_entry_a(&ud);
410 desc->b = LDT_entry_b(&ud);
413 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
415 struct desc_struct *desc = (void *)t->thread.tls_array;
418 (((u32)desc->base1) << 16) |
419 (((u32)desc->base2) << 24);
423 * This gets called before we allocate a new thread and copy
424 * the current task into it.
426 void prepare_to_copy(struct task_struct *tsk)
431 int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp,
432 unsigned long unused,
433 struct task_struct * p, struct pt_regs * regs)
436 struct pt_regs * childregs;
437 struct task_struct *me = current;
439 childregs = ((struct pt_regs *)
440 (THREAD_SIZE + task_stack_page(p))) - 1;
444 childregs->rsp = rsp;
446 childregs->rsp = (unsigned long)childregs;
448 p->thread.rsp = (unsigned long) childregs;
449 p->thread.rsp0 = (unsigned long) (childregs+1);
450 p->thread.userrsp = me->thread.userrsp;
452 set_tsk_thread_flag(p, TIF_FORK);
454 p->thread.fs = me->thread.fs;
455 p->thread.gs = me->thread.gs;
457 asm("mov %%gs,%0" : "=m" (p->thread.gsindex));
458 asm("mov %%fs,%0" : "=m" (p->thread.fsindex));
459 asm("mov %%es,%0" : "=m" (p->thread.es));
460 asm("mov %%ds,%0" : "=m" (p->thread.ds));
462 if (unlikely(me->thread.io_bitmap_ptr != NULL)) {
463 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
464 if (!p->thread.io_bitmap_ptr) {
465 p->thread.io_bitmap_max = 0;
468 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
473 * Set a new TLS for the child thread?
475 if (clone_flags & CLONE_SETTLS) {
476 #ifdef CONFIG_IA32_EMULATION
477 if (test_thread_flag(TIF_IA32))
478 err = ia32_child_tls(p, childregs);
481 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
487 if (err && p->thread.io_bitmap_ptr) {
488 kfree(p->thread.io_bitmap_ptr);
489 p->thread.io_bitmap_max = 0;
495 * This special macro can be used to load a debugging register
497 #define loaddebug(thread,r) set_debugreg(thread->debugreg ## r, r)
500 * switch_to(x,y) should switch tasks from x to y.
502 * This could still be optimized:
503 * - fold all the options into a flag word and test it with a single test.
504 * - could test fs/gs bitsliced
506 * Kprobes not supported here. Set the probe on schedule instead.
508 __kprobes struct task_struct *
509 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
511 struct thread_struct *prev = &prev_p->thread,
512 *next = &next_p->thread;
513 int cpu = smp_processor_id();
514 struct tss_struct *tss = &per_cpu(init_tss, cpu);
517 * Reload esp0, LDT and the page table pointer:
519 tss->rsp0 = next->rsp0;
523 * This won't pick up thread selector changes, but I guess that is ok.
525 asm volatile("mov %%es,%0" : "=m" (prev->es));
526 if (unlikely(next->es | prev->es))
527 loadsegment(es, next->es);
529 asm volatile ("mov %%ds,%0" : "=m" (prev->ds));
530 if (unlikely(next->ds | prev->ds))
531 loadsegment(ds, next->ds);
540 asm volatile("movl %%fs,%0" : "=r" (fsindex));
541 /* segment register != 0 always requires a reload.
542 also reload when it has changed.
543 when prev process used 64bit base always reload
544 to avoid an information leak. */
545 if (unlikely(fsindex | next->fsindex | prev->fs)) {
546 loadsegment(fs, next->fsindex);
547 /* check if the user used a selector != 0
548 * if yes clear 64bit base, since overloaded base
549 * is always mapped to the Null selector
554 /* when next process has a 64bit base use it */
556 wrmsrl(MSR_FS_BASE, next->fs);
557 prev->fsindex = fsindex;
561 asm volatile("movl %%gs,%0" : "=r" (gsindex));
562 if (unlikely(gsindex | next->gsindex | prev->gs)) {
563 load_gs_index(next->gsindex);
568 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
569 prev->gsindex = gsindex;
573 * Switch the PDA and FPU contexts.
575 prev->userrsp = read_pda(oldrsp);
576 write_pda(oldrsp, next->userrsp);
577 write_pda(pcurrent, next_p);
579 /* This must be here to ensure both math_state_restore() and
580 kernel_fpu_begin() work consistently.
581 And the AMD workaround requires it to be after DS reload. */
583 write_pda(kernelstack,
584 task_stack_page(next_p) + THREAD_SIZE - PDA_STACKOFFSET);
587 * Now maybe reload the debug registers
589 if (unlikely(next->debugreg7)) {
601 * Handle the IO bitmap
603 if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
604 if (next->io_bitmap_ptr)
606 * Copy the relevant range of the IO bitmap.
607 * Normally this is 128 bytes or less:
609 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
610 max(prev->io_bitmap_max, next->io_bitmap_max));
613 * Clear any possible leftover bits:
615 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
623 * sys_execve() executes a new program.
626 long sys_execve(char __user *name, char __user * __user *argv,
627 char __user * __user *envp, struct pt_regs regs)
632 filename = getname(name);
633 error = PTR_ERR(filename);
634 if (IS_ERR(filename))
636 error = do_execve(filename, argv, envp, ®s);
639 current->ptrace &= ~PT_DTRACE;
640 task_unlock(current);
646 void set_personality_64bit(void)
648 /* inherit personality from parent */
650 /* Make sure to be in 64bit mode */
651 clear_thread_flag(TIF_IA32);
654 asmlinkage long sys_fork(struct pt_regs *regs)
656 return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
660 sys_clone(unsigned long clone_flags, unsigned long newsp,
661 void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
665 return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
669 * This is trivial, and on the face of it looks like it
670 * could equally well be done in user mode.
672 * Not so, for quite unobvious reasons - register pressure.
673 * In user mode vfork() cannot have a stack frame, and if
674 * done by calling the "clone()" system call directly, you
675 * do not have enough call-clobbered registers to hold all
676 * the information you need.
678 asmlinkage long sys_vfork(struct pt_regs *regs)
680 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
684 unsigned long get_wchan(struct task_struct *p)
690 if (!p || p == current || p->state==TASK_RUNNING)
692 stack = (unsigned long)task_stack_page(p);
693 if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
695 fp = *(u64 *)(p->thread.rsp);
697 if (fp < (unsigned long)stack ||
698 fp > (unsigned long)stack+THREAD_SIZE)
700 rip = *(u64 *)(fp+8);
701 if (!in_sched_functions(rip))
704 } while (count++ < 16);
708 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
711 int doit = task == current;
716 if (addr >= TASK_SIZE_OF(task))
719 /* handle small bases via the GDT because that's faster to
721 if (addr <= 0xffffffff) {
722 set_32bit_tls(task, GS_TLS, addr);
724 load_TLS(&task->thread, cpu);
725 load_gs_index(GS_TLS_SEL);
727 task->thread.gsindex = GS_TLS_SEL;
730 task->thread.gsindex = 0;
731 task->thread.gs = addr;
734 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
740 /* Not strictly needed for fs, but do it for symmetry
742 if (addr >= TASK_SIZE_OF(task))
745 /* handle small bases via the GDT because that's faster to
747 if (addr <= 0xffffffff) {
748 set_32bit_tls(task, FS_TLS, addr);
750 load_TLS(&task->thread, cpu);
751 asm volatile("movl %0,%%fs" :: "r"(FS_TLS_SEL));
753 task->thread.fsindex = FS_TLS_SEL;
756 task->thread.fsindex = 0;
757 task->thread.fs = addr;
759 /* set the selector to 0 to not confuse
761 asm volatile("movl %0,%%fs" :: "r" (0));
762 ret = checking_wrmsrl(MSR_FS_BASE, addr);
769 if (task->thread.fsindex == FS_TLS_SEL)
770 base = read_32bit_tls(task, FS_TLS);
772 rdmsrl(MSR_FS_BASE, base);
774 base = task->thread.fs;
775 ret = put_user(base, (unsigned long __user *)addr);
781 if (task->thread.gsindex == GS_TLS_SEL)
782 base = read_32bit_tls(task, GS_TLS);
784 asm("movl %%gs,%0" : "=r" (gsindex));
786 rdmsrl(MSR_KERNEL_GS_BASE, base);
788 base = task->thread.gs;
791 base = task->thread.gs;
792 ret = put_user(base, (unsigned long __user *)addr);
804 long sys_arch_prctl(int code, unsigned long addr)
806 return do_arch_prctl(current, code, addr);
810 * Capture the user space registers if the task is not running (in user space)
812 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
814 struct pt_regs *pp, ptregs;
816 pp = task_pt_regs(tsk);
822 elf_core_copy_regs(regs, &ptregs);
827 unsigned long arch_align_stack(unsigned long sp)
829 if (randomize_va_space)
830 sp -= get_random_int() % 8192;