2 * Copyright (C) 1995 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
9 * This file handles the architecture-dependent parts of process handling..
14 #include <linux/cpu.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
18 #include <linux/kernel.h>
20 #include <linux/elfcore.h>
21 #include <linux/smp.h>
22 #include <linux/stddef.h>
23 #include <linux/slab.h>
24 #include <linux/vmalloc.h>
25 #include <linux/user.h>
26 #include <linux/interrupt.h>
27 #include <linux/utsname.h>
28 #include <linux/delay.h>
29 #include <linux/reboot.h>
30 #include <linux/init.h>
31 #include <linux/mc146818rtc.h>
32 #include <linux/module.h>
33 #include <linux/kallsyms.h>
34 #include <linux/ptrace.h>
35 #include <linux/random.h>
36 #include <linux/personality.h>
37 #include <linux/tick.h>
38 #include <linux/percpu.h>
39 #include <linux/prctl.h>
41 #include <asm/uaccess.h>
42 #include <asm/pgtable.h>
43 #include <asm/system.h>
46 #include <asm/processor.h>
49 #ifdef CONFIG_MATH_EMULATION
50 #include <asm/math_emu.h>
53 #include <linux/err.h>
55 #include <asm/tlbflush.h>
57 #include <asm/kdebug.h>
59 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
61 static int hlt_counter;
63 unsigned long boot_option_idle_override = 0;
64 EXPORT_SYMBOL(boot_option_idle_override);
66 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
67 EXPORT_PER_CPU_SYMBOL(current_task);
69 DEFINE_PER_CPU(int, cpu_number);
70 EXPORT_PER_CPU_SYMBOL(cpu_number);
73 * Return saved PC of a blocked thread.
75 unsigned long thread_saved_pc(struct task_struct *tsk)
77 return ((unsigned long *)tsk->thread.sp)[3];
81 * Powermanagement idle function, if any..
83 void (*pm_idle)(void);
84 EXPORT_SYMBOL(pm_idle);
86 void disable_hlt(void)
91 EXPORT_SYMBOL(disable_hlt);
98 EXPORT_SYMBOL(enable_hlt);
101 * We use this if we don't have any better
104 void default_idle(void)
106 if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
107 current_thread_info()->status &= ~TS_POLLING;
109 * TS_POLLING-cleared state must be visible before we
115 safe_halt(); /* enables interrupts racelessly */
118 current_thread_info()->status |= TS_POLLING;
121 /* loop is done by the caller */
125 #ifdef CONFIG_APM_MODULE
126 EXPORT_SYMBOL(default_idle);
129 #ifdef CONFIG_HOTPLUG_CPU
131 /* We don't actually take CPU down, just spin without interrupts. */
132 static inline void play_dead(void)
134 /* This must be done before dead CPU ack */
139 __get_cpu_var(cpu_state) = CPU_DEAD;
142 * With physical CPU hotplug, we should halt the cpu
149 static inline void play_dead(void)
153 #endif /* CONFIG_HOTPLUG_CPU */
156 * The idle thread. There's no useful work to be
157 * done, so just try to conserve power and have a
158 * low exit latency (ie sit in a loop waiting for
159 * somebody to say that they'd like to reschedule)
163 int cpu = smp_processor_id();
165 current_thread_info()->status |= TS_POLLING;
167 /* endless idle loop with no priority at all */
169 tick_nohz_stop_sched_tick();
170 while (!need_resched()) {
177 if (rcu_pending(cpu))
178 rcu_check_callbacks(cpu, 0);
183 if (cpu_is_offline(cpu))
187 __get_cpu_var(irq_stat).idle_timestamp = jiffies;
190 tick_nohz_restart_sched_tick();
191 preempt_enable_no_resched();
197 void __show_registers(struct pt_regs *regs, int all)
199 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
200 unsigned long d0, d1, d2, d3, d6, d7;
202 unsigned short ss, gs;
204 if (user_mode_vm(regs)) {
206 ss = regs->ss & 0xffff;
209 sp = (unsigned long) (®s->sp);
215 printk("Pid: %d, comm: %s %s (%s %.*s)\n",
216 task_pid_nr(current), current->comm,
217 print_tainted(), init_utsname()->release,
218 (int)strcspn(init_utsname()->version, " "),
219 init_utsname()->version);
221 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
222 (u16)regs->cs, regs->ip, regs->flags,
224 print_symbol("EIP is at %s\n", regs->ip);
226 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
227 regs->ax, regs->bx, regs->cx, regs->dx);
228 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
229 regs->si, regs->di, regs->bp, sp);
230 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
231 (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss);
239 cr4 = read_cr4_safe();
240 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
247 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
252 printk("DR6: %08lx DR7: %08lx\n",
256 void show_regs(struct pt_regs *regs)
258 __show_registers(regs, 1);
259 show_trace(NULL, regs, ®s->sp, regs->bp);
263 * This gets run with %bx containing the
264 * function to call, and %dx containing
267 extern void kernel_thread_helper(void);
270 * Create a kernel thread
272 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
276 memset(®s, 0, sizeof(regs));
278 regs.bx = (unsigned long) fn;
279 regs.dx = (unsigned long) arg;
283 regs.fs = __KERNEL_PERCPU;
285 regs.ip = (unsigned long) kernel_thread_helper;
286 regs.cs = __KERNEL_CS | get_kernel_rpl();
287 regs.flags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
289 /* Ok, create the new process.. */
290 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
292 EXPORT_SYMBOL(kernel_thread);
295 * Free current thread data structures etc..
297 void exit_thread(void)
299 /* The process may have allocated an io port bitmap... nuke it. */
300 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
301 struct task_struct *tsk = current;
302 struct thread_struct *t = &tsk->thread;
304 struct tss_struct *tss = &per_cpu(init_tss, cpu);
306 kfree(t->io_bitmap_ptr);
307 t->io_bitmap_ptr = NULL;
308 clear_thread_flag(TIF_IO_BITMAP);
310 * Careful, clear this in the TSS too:
312 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
313 t->io_bitmap_max = 0;
314 tss->io_bitmap_owner = NULL;
315 tss->io_bitmap_max = 0;
316 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
320 /* Free any DS contexts that have not been properly released. */
321 if (unlikely(current->thread.ds_ctx)) {
322 /* we clear debugctl to make sure DS is not used. */
323 update_debugctlmsr(0);
324 ds_free(current->thread.ds_ctx);
326 #endif /* CONFIG_X86_DS */
329 void flush_thread(void)
331 struct task_struct *tsk = current;
333 tsk->thread.debugreg0 = 0;
334 tsk->thread.debugreg1 = 0;
335 tsk->thread.debugreg2 = 0;
336 tsk->thread.debugreg3 = 0;
337 tsk->thread.debugreg6 = 0;
338 tsk->thread.debugreg7 = 0;
339 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
340 clear_tsk_thread_flag(tsk, TIF_DEBUG);
342 * Forget coprocessor state..
348 void release_thread(struct task_struct *dead_task)
350 BUG_ON(dead_task->mm);
351 release_vm86_irqs(dead_task);
355 * This gets called before we allocate a new thread and copy
356 * the current task into it.
358 void prepare_to_copy(struct task_struct *tsk)
363 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
364 unsigned long unused,
365 struct task_struct * p, struct pt_regs * regs)
367 struct pt_regs * childregs;
368 struct task_struct *tsk;
371 childregs = task_pt_regs(p);
376 p->thread.sp = (unsigned long) childregs;
377 p->thread.sp0 = (unsigned long) (childregs+1);
379 p->thread.ip = (unsigned long) ret_from_fork;
381 savesegment(gs, p->thread.gs);
384 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
385 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
386 IO_BITMAP_BYTES, GFP_KERNEL);
387 if (!p->thread.io_bitmap_ptr) {
388 p->thread.io_bitmap_max = 0;
391 set_tsk_thread_flag(p, TIF_IO_BITMAP);
397 * Set a new TLS for the child thread?
399 if (clone_flags & CLONE_SETTLS)
400 err = do_set_thread_area(p, -1,
401 (struct user_desc __user *)childregs->si, 0);
403 if (err && p->thread.io_bitmap_ptr) {
404 kfree(p->thread.io_bitmap_ptr);
405 p->thread.io_bitmap_max = 0;
411 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
413 __asm__("movl %0, %%gs" :: "r"(0));
416 regs->ds = __USER_DS;
417 regs->es = __USER_DS;
418 regs->ss = __USER_DS;
419 regs->cs = __USER_CS;
423 * Free the old FP and other extended state
425 free_thread_xstate(current);
427 EXPORT_SYMBOL_GPL(start_thread);
429 static void hard_disable_TSC(void)
431 write_cr4(read_cr4() | X86_CR4_TSD);
434 void disable_TSC(void)
437 if (!test_and_set_thread_flag(TIF_NOTSC))
439 * Must flip the CPU state synchronously with
440 * TIF_NOTSC in the current running context.
446 static void hard_enable_TSC(void)
448 write_cr4(read_cr4() & ~X86_CR4_TSD);
451 static void enable_TSC(void)
454 if (test_and_clear_thread_flag(TIF_NOTSC))
456 * Must flip the CPU state synchronously with
457 * TIF_NOTSC in the current running context.
463 int get_tsc_mode(unsigned long adr)
467 if (test_thread_flag(TIF_NOTSC))
468 val = PR_TSC_SIGSEGV;
472 return put_user(val, (unsigned int __user *)adr);
475 int set_tsc_mode(unsigned int val)
477 if (val == PR_TSC_SIGSEGV)
479 else if (val == PR_TSC_ENABLE)
488 static int update_debugctl(struct thread_struct *prev,
489 struct thread_struct *next, unsigned long debugctl)
491 unsigned long ds_prev = 0;
492 unsigned long ds_next = 0;
495 ds_prev = (unsigned long)prev->ds_ctx->ds;
497 ds_next = (unsigned long)next->ds_ctx->ds;
499 if (ds_next != ds_prev) {
500 /* we clear debugctl to make sure DS
501 * is not in use when we change it */
503 update_debugctlmsr(0);
504 wrmsr(MSR_IA32_DS_AREA, ds_next, 0);
509 static int update_debugctl(struct thread_struct *prev,
510 struct thread_struct *next, unsigned long debugctl)
514 #endif /* CONFIG_X86_DS */
517 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
518 struct tss_struct *tss)
520 struct thread_struct *prev, *next;
521 unsigned long debugctl;
523 prev = &prev_p->thread;
524 next = &next_p->thread;
526 debugctl = update_debugctl(prev, next, prev->debugctlmsr);
528 if (next->debugctlmsr != debugctl)
529 update_debugctlmsr(next->debugctlmsr);
531 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
532 set_debugreg(next->debugreg0, 0);
533 set_debugreg(next->debugreg1, 1);
534 set_debugreg(next->debugreg2, 2);
535 set_debugreg(next->debugreg3, 3);
537 set_debugreg(next->debugreg6, 6);
538 set_debugreg(next->debugreg7, 7);
541 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
542 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
543 /* prev and next are different */
544 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
550 #ifdef CONFIG_X86_PTRACE_BTS
551 if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
552 ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
554 if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
555 ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
556 #endif /* CONFIG_X86_PTRACE_BTS */
559 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
561 * Disable the bitmap via an invalid offset. We still cache
562 * the previous bitmap owner and the IO bitmap contents:
564 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
568 if (likely(next == tss->io_bitmap_owner)) {
570 * Previous owner of the bitmap (hence the bitmap content)
571 * matches the next task, we dont have to do anything but
572 * to set a valid offset in the TSS:
574 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
578 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
579 * and we let the task to get a GPF in case an I/O instruction
580 * is performed. The handler of the GPF will verify that the
581 * faulting task has a valid I/O bitmap and, it true, does the
582 * real copy and restart the instruction. This will save us
583 * redundant copies when the currently switched task does not
584 * perform any I/O during its timeslice.
586 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
590 * switch_to(x,yn) should switch tasks from x to y.
592 * We fsave/fwait so that an exception goes off at the right time
593 * (as a call from the fsave or fwait in effect) rather than to
594 * the wrong process. Lazy FP saving no longer makes any sense
595 * with modern CPU's, and this simplifies a lot of things (SMP
596 * and UP become the same).
598 * NOTE! We used to use the x86 hardware context switching. The
599 * reason for not using it any more becomes apparent when you
600 * try to recover gracefully from saved state that is no longer
601 * valid (stale segment register values in particular). With the
602 * hardware task-switch, there is no way to fix up bad state in
603 * a reasonable manner.
605 * The fact that Intel documents the hardware task-switching to
606 * be slow is a fairly red herring - this code is not noticeably
607 * faster. However, there _is_ some room for improvement here,
608 * so the performance issues may eventually be a valid point.
609 * More important, however, is the fact that this allows us much
612 * The return value (in %ax) will be the "prev" task after
613 * the task-switch, and shows up in ret_from_fork in entry.S,
616 struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
618 struct thread_struct *prev = &prev_p->thread,
619 *next = &next_p->thread;
620 int cpu = smp_processor_id();
621 struct tss_struct *tss = &per_cpu(init_tss, cpu);
623 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
625 __unlazy_fpu(prev_p);
628 /* we're going to use this soon, after a few expensive things */
629 if (next_p->fpu_counter > 5)
630 prefetch(next->xstate);
638 * Save away %gs. No need to save %fs, as it was saved on the
639 * stack on entry. No need to save %es and %ds, as those are
640 * always kernel segments while inside the kernel. Doing this
641 * before setting the new TLS descriptors avoids the situation
642 * where we temporarily have non-reloadable segments in %fs
643 * and %gs. This could be an issue if the NMI handler ever
644 * used %fs or %gs (it does not today), or if the kernel is
645 * running inside of a hypervisor layer.
647 savesegment(gs, prev->gs);
650 * Load the per-thread Thread-Local Storage descriptor.
655 * Restore IOPL if needed. In normal use, the flags restore
656 * in the switch assembly will handle this. But if the kernel
657 * is running virtualized at a non-zero CPL, the popf will
658 * not restore flags, so it must be done in a separate step.
660 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
661 set_iopl_mask(next->iopl);
664 * Now maybe handle debug registers and/or IO bitmaps
666 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
667 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
668 __switch_to_xtra(prev_p, next_p, tss);
671 * Leave lazy mode, flushing any hypercalls made here.
672 * This must be done before restoring TLS segments so
673 * the GDT and LDT are properly updated, and must be
674 * done before math_state_restore, so the TS bit is up
677 arch_leave_lazy_cpu_mode();
679 /* If the task has used fpu the last 5 timeslices, just do a full
680 * restore of the math state immediately to avoid the trap; the
681 * chances of needing FPU soon are obviously high now
683 if (next_p->fpu_counter > 5)
684 math_state_restore();
687 * Restore %gs if needed (which is common)
689 if (prev->gs | next->gs)
690 loadsegment(gs, next->gs);
692 x86_write_percpu(current_task, next_p);
697 asmlinkage int sys_fork(struct pt_regs regs)
699 return do_fork(SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
702 asmlinkage int sys_clone(struct pt_regs regs)
704 unsigned long clone_flags;
706 int __user *parent_tidptr, *child_tidptr;
708 clone_flags = regs.bx;
710 parent_tidptr = (int __user *)regs.dx;
711 child_tidptr = (int __user *)regs.di;
714 return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
718 * This is trivial, and on the face of it looks like it
719 * could equally well be done in user mode.
721 * Not so, for quite unobvious reasons - register pressure.
722 * In user mode vfork() cannot have a stack frame, and if
723 * done by calling the "clone()" system call directly, you
724 * do not have enough call-clobbered registers to hold all
725 * the information you need.
727 asmlinkage int sys_vfork(struct pt_regs regs)
729 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
733 * sys_execve() executes a new program.
735 asmlinkage int sys_execve(struct pt_regs regs)
740 filename = getname((char __user *) regs.bx);
741 error = PTR_ERR(filename);
742 if (IS_ERR(filename))
744 error = do_execve(filename,
745 (char __user * __user *) regs.cx,
746 (char __user * __user *) regs.dx,
749 /* Make sure we don't return using sysenter.. */
750 set_thread_flag(TIF_IRET);
757 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
758 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
760 unsigned long get_wchan(struct task_struct *p)
762 unsigned long bp, sp, ip;
763 unsigned long stack_page;
765 if (!p || p == current || p->state == TASK_RUNNING)
767 stack_page = (unsigned long)task_stack_page(p);
769 if (!stack_page || sp < stack_page || sp > top_esp+stack_page)
771 /* include/asm-i386/system.h:switch_to() pushes bp last. */
772 bp = *(unsigned long *) sp;
774 if (bp < stack_page || bp > top_ebp+stack_page)
776 ip = *(unsigned long *) (bp+4);
777 if (!in_sched_functions(ip))
779 bp = *(unsigned long *) bp;
780 } while (count++ < 16);
784 unsigned long arch_align_stack(unsigned long sp)
786 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
787 sp -= get_random_int() % 8192;
791 unsigned long arch_randomize_brk(struct mm_struct *mm)
793 unsigned long range_end = mm->brk + 0x02000000;
794 return randomize_range(mm->brk, range_end, 0) ? : mm->brk;