2 * Copyright (C) 1995 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
10 * CPU hotplug support - ashok.raj@intel.com
14 * This file handles the architecture-dependent parts of process handling..
19 #include <linux/cpu.h>
20 #include <linux/errno.h>
21 #include <linux/sched.h>
23 #include <linux/kernel.h>
25 #include <linux/elfcore.h>
26 #include <linux/smp.h>
27 #include <linux/slab.h>
28 #include <linux/user.h>
29 #include <linux/interrupt.h>
30 #include <linux/utsname.h>
31 #include <linux/delay.h>
32 #include <linux/module.h>
33 #include <linux/ptrace.h>
34 #include <linux/random.h>
35 #include <linux/notifier.h>
36 #include <linux/kprobes.h>
37 #include <linux/kdebug.h>
38 #include <linux/tick.h>
39 #include <linux/prctl.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>
51 #include <asm/proto.h>
55 asmlinkage extern void ret_from_fork(void);
57 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
59 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
61 void idle_notifier_register(struct notifier_block *n)
63 atomic_notifier_chain_register(&idle_notifier, n);
65 EXPORT_SYMBOL_GPL(idle_notifier_register);
67 void idle_notifier_unregister(struct notifier_block *n)
69 atomic_notifier_chain_unregister(&idle_notifier, n);
71 EXPORT_SYMBOL_GPL(idle_notifier_unregister);
76 atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
79 static void __exit_idle(void)
81 if (test_and_clear_bit_pda(0, isidle) == 0)
83 atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
86 /* Called from interrupts to signify idle end */
89 /* idle loop has pid 0 */
95 #ifdef CONFIG_HOTPLUG_CPU
96 DECLARE_PER_CPU(int, cpu_state);
99 /* We halt the CPU with physical CPU hotplug */
100 static inline void play_dead(void)
103 c1e_remove_cpu(raw_smp_processor_id());
107 __get_cpu_var(cpu_state) = CPU_DEAD;
110 /* mask all interrupts, flush any and all caches, and halt */
114 static inline void play_dead(void)
118 #endif /* CONFIG_HOTPLUG_CPU */
121 * The idle thread. There's no useful work to be
122 * done, so just try to conserve power and have a
123 * low exit latency (ie sit in a loop waiting for
124 * somebody to say that they'd like to reschedule)
128 current_thread_info()->status |= TS_POLLING;
129 /* endless idle loop with no priority at all */
131 tick_nohz_stop_sched_tick(1);
132 while (!need_resched()) {
136 if (cpu_is_offline(smp_processor_id()))
139 * Idle routines should keep interrupts disabled
140 * from here on, until they go to idle.
141 * Otherwise, idle callbacks can misfire.
145 /* Don't trace irqs off for idle */
146 stop_critical_timings();
148 start_critical_timings();
149 /* In many cases the interrupt that ended idle
150 has already called exit_idle. But some idle
151 loops can be woken up without interrupt. */
155 tick_nohz_restart_sched_tick();
156 preempt_enable_no_resched();
162 /* Prints also some state that isn't saved in the pt_regs */
163 void __show_regs(struct pt_regs * regs)
165 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
166 unsigned long d0, d1, d2, d3, d6, d7;
167 unsigned int fsindex, gsindex;
168 unsigned int ds, cs, es;
172 printk("Pid: %d, comm: %.20s %s %s %.*s\n",
173 current->pid, current->comm, print_tainted(),
174 init_utsname()->release,
175 (int)strcspn(init_utsname()->version, " "),
176 init_utsname()->version);
177 printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
178 printk_address(regs->ip, 1);
179 printk("RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss, regs->sp,
181 printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
182 regs->ax, regs->bx, regs->cx);
183 printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
184 regs->dx, regs->si, regs->di);
185 printk("RBP: %016lx R08: %016lx R09: %016lx\n",
186 regs->bp, regs->r8, regs->r9);
187 printk("R10: %016lx R11: %016lx R12: %016lx\n",
188 regs->r10, regs->r11, regs->r12);
189 printk("R13: %016lx R14: %016lx R15: %016lx\n",
190 regs->r13, regs->r14, regs->r15);
192 asm("movl %%ds,%0" : "=r" (ds));
193 asm("movl %%cs,%0" : "=r" (cs));
194 asm("movl %%es,%0" : "=r" (es));
195 asm("movl %%fs,%0" : "=r" (fsindex));
196 asm("movl %%gs,%0" : "=r" (gsindex));
198 rdmsrl(MSR_FS_BASE, fs);
199 rdmsrl(MSR_GS_BASE, gs);
200 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
207 printk("FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
208 fs,fsindex,gs,gsindex,shadowgs);
209 printk("CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0);
210 printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
215 printk("DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
219 printk("DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
222 void show_regs(struct pt_regs *regs)
224 printk("CPU %d:", smp_processor_id());
226 show_trace(NULL, regs, (void *)(regs + 1), regs->bp);
230 * Free current thread data structures etc..
232 void exit_thread(void)
234 struct task_struct *me = current;
235 struct thread_struct *t = &me->thread;
237 if (me->thread.io_bitmap_ptr) {
238 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
240 kfree(t->io_bitmap_ptr);
241 t->io_bitmap_ptr = NULL;
242 clear_thread_flag(TIF_IO_BITMAP);
244 * Careful, clear this in the TSS too:
246 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
247 t->io_bitmap_max = 0;
252 void flush_thread(void)
254 struct task_struct *tsk = current;
256 if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
257 clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
258 if (test_tsk_thread_flag(tsk, TIF_IA32)) {
259 clear_tsk_thread_flag(tsk, TIF_IA32);
261 set_tsk_thread_flag(tsk, TIF_IA32);
262 current_thread_info()->status |= TS_COMPAT;
265 clear_tsk_thread_flag(tsk, TIF_DEBUG);
267 tsk->thread.debugreg0 = 0;
268 tsk->thread.debugreg1 = 0;
269 tsk->thread.debugreg2 = 0;
270 tsk->thread.debugreg3 = 0;
271 tsk->thread.debugreg6 = 0;
272 tsk->thread.debugreg7 = 0;
273 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
275 * Forget coprocessor state..
277 tsk->fpu_counter = 0;
282 void release_thread(struct task_struct *dead_task)
285 if (dead_task->mm->context.size) {
286 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
288 dead_task->mm->context.ldt,
289 dead_task->mm->context.size);
295 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
297 struct user_desc ud = {
304 struct desc_struct *desc = t->thread.tls_array;
309 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
311 return get_desc_base(&t->thread.tls_array[tls]);
315 * This gets called before we allocate a new thread and copy
316 * the current task into it.
318 void prepare_to_copy(struct task_struct *tsk)
323 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
324 unsigned long unused,
325 struct task_struct * p, struct pt_regs * regs)
328 struct pt_regs * childregs;
329 struct task_struct *me = current;
331 childregs = ((struct pt_regs *)
332 (THREAD_SIZE + task_stack_page(p))) - 1;
338 childregs->sp = (unsigned long)childregs;
340 p->thread.sp = (unsigned long) childregs;
341 p->thread.sp0 = (unsigned long) (childregs+1);
342 p->thread.usersp = me->thread.usersp;
344 set_tsk_thread_flag(p, TIF_FORK);
346 p->thread.fs = me->thread.fs;
347 p->thread.gs = me->thread.gs;
349 savesegment(gs, p->thread.gsindex);
350 savesegment(fs, p->thread.fsindex);
351 savesegment(es, p->thread.es);
352 savesegment(ds, p->thread.ds);
354 if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
355 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
356 if (!p->thread.io_bitmap_ptr) {
357 p->thread.io_bitmap_max = 0;
360 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
362 set_tsk_thread_flag(p, TIF_IO_BITMAP);
366 * Set a new TLS for the child thread?
368 if (clone_flags & CLONE_SETTLS) {
369 #ifdef CONFIG_IA32_EMULATION
370 if (test_thread_flag(TIF_IA32))
371 err = do_set_thread_area(p, -1,
372 (struct user_desc __user *)childregs->si, 0);
375 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
381 if (err && p->thread.io_bitmap_ptr) {
382 kfree(p->thread.io_bitmap_ptr);
383 p->thread.io_bitmap_max = 0;
389 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
397 write_pda(oldrsp, new_sp);
398 regs->cs = __USER_CS;
399 regs->ss = __USER_DS;
403 * Free the old FP and other extended state
405 free_thread_xstate(current);
407 EXPORT_SYMBOL_GPL(start_thread);
409 static void hard_disable_TSC(void)
411 write_cr4(read_cr4() | X86_CR4_TSD);
414 void disable_TSC(void)
417 if (!test_and_set_thread_flag(TIF_NOTSC))
419 * Must flip the CPU state synchronously with
420 * TIF_NOTSC in the current running context.
426 static void hard_enable_TSC(void)
428 write_cr4(read_cr4() & ~X86_CR4_TSD);
431 static void enable_TSC(void)
434 if (test_and_clear_thread_flag(TIF_NOTSC))
436 * Must flip the CPU state synchronously with
437 * TIF_NOTSC in the current running context.
443 int get_tsc_mode(unsigned long adr)
447 if (test_thread_flag(TIF_NOTSC))
448 val = PR_TSC_SIGSEGV;
452 return put_user(val, (unsigned int __user *)adr);
455 int set_tsc_mode(unsigned int val)
457 if (val == PR_TSC_SIGSEGV)
459 else if (val == PR_TSC_ENABLE)
468 * This special macro can be used to load a debugging register
470 #define loaddebug(thread, r) set_debugreg(thread->debugreg ## r, r)
472 static inline void __switch_to_xtra(struct task_struct *prev_p,
473 struct task_struct *next_p,
474 struct tss_struct *tss)
476 struct thread_struct *prev, *next;
477 unsigned long debugctl;
479 prev = &prev_p->thread,
480 next = &next_p->thread;
482 debugctl = prev->debugctlmsr;
483 if (next->ds_area_msr != prev->ds_area_msr) {
484 /* we clear debugctl to make sure DS
485 * is not in use when we change it */
487 update_debugctlmsr(0);
488 wrmsrl(MSR_IA32_DS_AREA, next->ds_area_msr);
491 if (next->debugctlmsr != debugctl)
492 update_debugctlmsr(next->debugctlmsr);
494 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
504 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
505 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
506 /* prev and next are different */
507 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
513 if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
515 * Copy the relevant range of the IO bitmap.
516 * Normally this is 128 bytes or less:
518 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
519 max(prev->io_bitmap_max, next->io_bitmap_max));
520 } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
522 * Clear any possible leftover bits:
524 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
528 if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
529 ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
531 if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
532 ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
537 * switch_to(x,y) should switch tasks from x to y.
539 * This could still be optimized:
540 * - fold all the options into a flag word and test it with a single test.
541 * - could test fs/gs bitsliced
543 * Kprobes not supported here. Set the probe on schedule instead.
546 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
548 struct thread_struct *prev = &prev_p->thread;
549 struct thread_struct *next = &next_p->thread;
550 int cpu = smp_processor_id();
551 struct tss_struct *tss = &per_cpu(init_tss, cpu);
552 unsigned fsindex, gsindex;
554 /* we're going to use this soon, after a few expensive things */
555 if (next_p->fpu_counter>5)
556 prefetch(next->xstate);
559 * Reload esp0, LDT and the page table pointer:
565 * This won't pick up thread selector changes, but I guess that is ok.
567 savesegment(es, prev->es);
568 if (unlikely(next->es | prev->es))
569 loadsegment(es, next->es);
571 savesegment(ds, prev->ds);
572 if (unlikely(next->ds | prev->ds))
573 loadsegment(ds, next->ds);
576 /* We must save %fs and %gs before load_TLS() because
577 * %fs and %gs may be cleared by load_TLS().
579 * (e.g. xen_load_tls())
581 savesegment(fs, fsindex);
582 savesegment(gs, gsindex);
587 * Leave lazy mode, flushing any hypercalls made here.
588 * This must be done before restoring TLS segments so
589 * the GDT and LDT are properly updated, and must be
590 * done before math_state_restore, so the TS bit is up
593 arch_leave_lazy_cpu_mode();
598 * Segment register != 0 always requires a reload. Also
599 * reload when it has changed. When prev process used 64bit
600 * base always reload to avoid an information leak.
602 if (unlikely(fsindex | next->fsindex | prev->fs)) {
603 loadsegment(fs, next->fsindex);
605 * Check if the user used a selector != 0; if yes
606 * clear 64bit base, since overloaded base is always
607 * mapped to the Null selector
612 /* when next process has a 64bit base use it */
614 wrmsrl(MSR_FS_BASE, next->fs);
615 prev->fsindex = fsindex;
617 if (unlikely(gsindex | next->gsindex | prev->gs)) {
618 load_gs_index(next->gsindex);
623 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
624 prev->gsindex = gsindex;
626 /* Must be after DS reload */
630 * Switch the PDA and FPU contexts.
632 prev->usersp = read_pda(oldrsp);
633 write_pda(oldrsp, next->usersp);
634 write_pda(pcurrent, next_p);
636 write_pda(kernelstack,
637 (unsigned long)task_stack_page(next_p) +
638 THREAD_SIZE - PDA_STACKOFFSET);
639 #ifdef CONFIG_CC_STACKPROTECTOR
640 write_pda(stack_canary, next_p->stack_canary);
642 * Build time only check to make sure the stack_canary is at
643 * offset 40 in the pda; this is a gcc ABI requirement
645 BUILD_BUG_ON(offsetof(struct x8664_pda, stack_canary) != 40);
649 * Now maybe reload the debug registers and handle I/O bitmaps
651 if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
652 task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
653 __switch_to_xtra(prev_p, next_p, tss);
655 /* If the task has used fpu the last 5 timeslices, just do a full
656 * restore of the math state immediately to avoid the trap; the
657 * chances of needing FPU soon are obviously high now
659 * tsk_used_math() checks prevent calling math_state_restore(),
660 * which can sleep in the case of !tsk_used_math()
662 if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
663 math_state_restore();
668 * sys_execve() executes a new program.
671 long sys_execve(char __user *name, char __user * __user *argv,
672 char __user * __user *envp, struct pt_regs *regs)
677 filename = getname(name);
678 error = PTR_ERR(filename);
679 if (IS_ERR(filename))
681 error = do_execve(filename, argv, envp, regs);
686 void set_personality_64bit(void)
688 /* inherit personality from parent */
690 /* Make sure to be in 64bit mode */
691 clear_thread_flag(TIF_IA32);
693 /* TBD: overwrites user setup. Should have two bits.
694 But 64bit processes have always behaved this way,
695 so it's not too bad. The main problem is just that
696 32bit childs are affected again. */
697 current->personality &= ~READ_IMPLIES_EXEC;
700 asmlinkage long sys_fork(struct pt_regs *regs)
702 return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
706 sys_clone(unsigned long clone_flags, unsigned long newsp,
707 void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
711 return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
715 * This is trivial, and on the face of it looks like it
716 * could equally well be done in user mode.
718 * Not so, for quite unobvious reasons - register pressure.
719 * In user mode vfork() cannot have a stack frame, and if
720 * done by calling the "clone()" system call directly, you
721 * do not have enough call-clobbered registers to hold all
722 * the information you need.
724 asmlinkage long sys_vfork(struct pt_regs *regs)
726 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
730 unsigned long get_wchan(struct task_struct *p)
736 if (!p || p == current || p->state==TASK_RUNNING)
738 stack = (unsigned long)task_stack_page(p);
739 if (p->thread.sp < stack || p->thread.sp > stack+THREAD_SIZE)
741 fp = *(u64 *)(p->thread.sp);
743 if (fp < (unsigned long)stack ||
744 fp > (unsigned long)stack+THREAD_SIZE)
747 if (!in_sched_functions(ip))
750 } while (count++ < 16);
754 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
757 int doit = task == current;
762 if (addr >= TASK_SIZE_OF(task))
765 /* handle small bases via the GDT because that's faster to
767 if (addr <= 0xffffffff) {
768 set_32bit_tls(task, GS_TLS, addr);
770 load_TLS(&task->thread, cpu);
771 load_gs_index(GS_TLS_SEL);
773 task->thread.gsindex = GS_TLS_SEL;
776 task->thread.gsindex = 0;
777 task->thread.gs = addr;
780 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
786 /* Not strictly needed for fs, but do it for symmetry
788 if (addr >= TASK_SIZE_OF(task))
791 /* handle small bases via the GDT because that's faster to
793 if (addr <= 0xffffffff) {
794 set_32bit_tls(task, FS_TLS, addr);
796 load_TLS(&task->thread, cpu);
797 loadsegment(fs, FS_TLS_SEL);
799 task->thread.fsindex = FS_TLS_SEL;
802 task->thread.fsindex = 0;
803 task->thread.fs = addr;
805 /* set the selector to 0 to not confuse
808 ret = checking_wrmsrl(MSR_FS_BASE, addr);
815 if (task->thread.fsindex == FS_TLS_SEL)
816 base = read_32bit_tls(task, FS_TLS);
818 rdmsrl(MSR_FS_BASE, base);
820 base = task->thread.fs;
821 ret = put_user(base, (unsigned long __user *)addr);
827 if (task->thread.gsindex == GS_TLS_SEL)
828 base = read_32bit_tls(task, GS_TLS);
830 savesegment(gs, gsindex);
832 rdmsrl(MSR_KERNEL_GS_BASE, base);
834 base = task->thread.gs;
837 base = task->thread.gs;
838 ret = put_user(base, (unsigned long __user *)addr);
850 long sys_arch_prctl(int code, unsigned long addr)
852 return do_arch_prctl(current, code, addr);
855 unsigned long arch_align_stack(unsigned long sp)
857 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
858 sp -= get_random_int() % 8192;
862 unsigned long arch_randomize_brk(struct mm_struct *mm)
864 unsigned long range_end = mm->brk + 0x02000000;
865 return randomize_range(mm->brk, range_end, 0) ? : mm->brk;