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..
17 #include <linux/stackprotector.h>
18 #include <linux/cpu.h>
19 #include <linux/errno.h>
20 #include <linux/sched.h>
22 #include <linux/kernel.h>
24 #include <linux/elfcore.h>
25 #include <linux/smp.h>
26 #include <linux/slab.h>
27 #include <linux/user.h>
28 #include <linux/interrupt.h>
29 #include <linux/delay.h>
30 #include <linux/module.h>
31 #include <linux/ptrace.h>
32 #include <linux/notifier.h>
33 #include <linux/kprobes.h>
34 #include <linux/kdebug.h>
35 #include <linux/tick.h>
36 #include <linux/prctl.h>
37 #include <linux/uaccess.h>
39 #include <linux/ftrace.h>
40 #include <linux/cpuidle.h>
42 #include <asm/pgtable.h>
43 #include <asm/system.h>
44 #include <asm/processor.h>
46 #include <asm/mmu_context.h>
47 #include <asm/prctl.h>
49 #include <asm/proto.h>
52 #include <asm/syscalls.h>
53 #include <asm/debugreg.h>
56 asmlinkage extern void ret_from_fork(void);
58 DEFINE_PER_CPU(unsigned long, old_rsp);
59 static DEFINE_PER_CPU(unsigned char, is_idle);
61 static ATOMIC_NOTIFIER_HEAD(idle_notifier);
63 void idle_notifier_register(struct notifier_block *n)
65 atomic_notifier_chain_register(&idle_notifier, n);
67 EXPORT_SYMBOL_GPL(idle_notifier_register);
69 void idle_notifier_unregister(struct notifier_block *n)
71 atomic_notifier_chain_unregister(&idle_notifier, n);
73 EXPORT_SYMBOL_GPL(idle_notifier_unregister);
77 percpu_write(is_idle, 1);
78 atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
81 static void __exit_idle(void)
83 if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
85 atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
88 /* Called from interrupts to signify idle end */
91 /* idle loop has pid 0 */
98 static inline void play_dead(void)
105 * The idle thread. There's no useful work to be
106 * done, so just try to conserve power and have a
107 * low exit latency (ie sit in a loop waiting for
108 * somebody to say that they'd like to reschedule)
112 current_thread_info()->status |= TS_POLLING;
115 * If we're the non-boot CPU, nothing set the stack canary up
116 * for us. CPU0 already has it initialized but no harm in
117 * doing it again. This is a good place for updating it, as
118 * we wont ever return from this function (so the invalid
119 * canaries already on the stack wont ever trigger).
121 boot_init_stack_canary();
123 /* endless idle loop with no priority at all */
125 tick_nohz_idle_enter();
126 while (!need_resched()) {
130 if (cpu_is_offline(smp_processor_id()))
133 * Idle routines should keep interrupts disabled
134 * from here on, until they go to idle.
135 * Otherwise, idle callbacks can misfire.
140 /* Don't trace irqs off for idle */
141 stop_critical_timings();
143 /* enter_idle() needs rcu for notifiers */
146 if (cpuidle_idle_call())
150 start_critical_timings();
152 /* In many cases the interrupt that ended idle
153 has already called exit_idle. But some idle
154 loops can be woken up without interrupt. */
158 tick_nohz_idle_exit();
159 preempt_enable_no_resched();
165 /* Prints also some state that isn't saved in the pt_regs */
166 void __show_regs(struct pt_regs *regs, int all)
168 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
169 unsigned long d0, d1, d2, d3, d6, d7;
170 unsigned int fsindex, gsindex;
171 unsigned int ds, cs, es;
174 printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
175 printk_address(regs->ip, 1);
176 printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss,
177 regs->sp, regs->flags);
178 printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",
179 regs->ax, regs->bx, regs->cx);
180 printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n",
181 regs->dx, regs->si, regs->di);
182 printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n",
183 regs->bp, regs->r8, regs->r9);
184 printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n",
185 regs->r10, regs->r11, regs->r12);
186 printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n",
187 regs->r13, regs->r14, regs->r15);
189 asm("movl %%ds,%0" : "=r" (ds));
190 asm("movl %%cs,%0" : "=r" (cs));
191 asm("movl %%es,%0" : "=r" (es));
192 asm("movl %%fs,%0" : "=r" (fsindex));
193 asm("movl %%gs,%0" : "=r" (gsindex));
195 rdmsrl(MSR_FS_BASE, fs);
196 rdmsrl(MSR_GS_BASE, gs);
197 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
207 printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
208 fs, fsindex, gs, gsindex, shadowgs);
209 printk(KERN_DEFAULT "CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds,
211 printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3,
217 printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
221 printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
224 void release_thread(struct task_struct *dead_task)
227 if (dead_task->mm->context.size) {
228 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
230 dead_task->mm->context.ldt,
231 dead_task->mm->context.size);
237 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
239 struct user_desc ud = {
246 struct desc_struct *desc = t->thread.tls_array;
251 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
253 return get_desc_base(&t->thread.tls_array[tls]);
257 * This gets called before we allocate a new thread and copy
258 * the current task into it.
260 void prepare_to_copy(struct task_struct *tsk)
265 int copy_thread(unsigned long clone_flags, unsigned long sp,
266 unsigned long unused,
267 struct task_struct *p, struct pt_regs *regs)
270 struct pt_regs *childregs;
271 struct task_struct *me = current;
273 childregs = ((struct pt_regs *)
274 (THREAD_SIZE + task_stack_page(p))) - 1;
281 childregs->sp = (unsigned long)childregs;
283 p->thread.sp = (unsigned long) childregs;
284 p->thread.sp0 = (unsigned long) (childregs+1);
285 p->thread.usersp = me->thread.usersp;
287 set_tsk_thread_flag(p, TIF_FORK);
289 p->thread.io_bitmap_ptr = NULL;
291 savesegment(gs, p->thread.gsindex);
292 p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs;
293 savesegment(fs, p->thread.fsindex);
294 p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
295 savesegment(es, p->thread.es);
296 savesegment(ds, p->thread.ds);
299 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
301 if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
302 p->thread.io_bitmap_ptr = kmemdup(me->thread.io_bitmap_ptr,
303 IO_BITMAP_BYTES, GFP_KERNEL);
304 if (!p->thread.io_bitmap_ptr) {
305 p->thread.io_bitmap_max = 0;
308 set_tsk_thread_flag(p, TIF_IO_BITMAP);
312 * Set a new TLS for the child thread?
314 if (clone_flags & CLONE_SETTLS) {
315 #ifdef CONFIG_IA32_EMULATION
316 if (test_thread_flag(TIF_IA32))
317 err = do_set_thread_area(p, -1,
318 (struct user_desc __user *)childregs->si, 0);
321 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
327 if (err && p->thread.io_bitmap_ptr) {
328 kfree(p->thread.io_bitmap_ptr);
329 p->thread.io_bitmap_max = 0;
336 start_thread_common(struct pt_regs *regs, unsigned long new_ip,
337 unsigned long new_sp,
338 unsigned int _cs, unsigned int _ss, unsigned int _ds)
341 loadsegment(es, _ds);
342 loadsegment(ds, _ds);
346 percpu_write(old_rsp, new_sp);
349 regs->flags = X86_EFLAGS_IF;
351 * Free the old FP and other extended state
353 free_thread_xstate(current);
357 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
359 start_thread_common(regs, new_ip, new_sp,
360 __USER_CS, __USER_DS, 0);
363 #ifdef CONFIG_IA32_EMULATION
364 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp)
366 start_thread_common(regs, new_ip, new_sp,
367 __USER32_CS, __USER32_DS, __USER32_DS);
372 * switch_to(x,y) should switch tasks from x to y.
374 * This could still be optimized:
375 * - fold all the options into a flag word and test it with a single test.
376 * - could test fs/gs bitsliced
378 * Kprobes not supported here. Set the probe on schedule instead.
379 * Function graph tracer not supported too.
381 __notrace_funcgraph struct task_struct *
382 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
384 struct thread_struct *prev = &prev_p->thread;
385 struct thread_struct *next = &next_p->thread;
386 int cpu = smp_processor_id();
387 struct tss_struct *tss = &per_cpu(init_tss, cpu);
388 unsigned fsindex, gsindex;
390 __unlazy_fpu(prev_p);
393 * Reload esp0, LDT and the page table pointer:
399 * This won't pick up thread selector changes, but I guess that is ok.
401 savesegment(es, prev->es);
402 if (unlikely(next->es | prev->es))
403 loadsegment(es, next->es);
405 savesegment(ds, prev->ds);
406 if (unlikely(next->ds | prev->ds))
407 loadsegment(ds, next->ds);
410 /* We must save %fs and %gs before load_TLS() because
411 * %fs and %gs may be cleared by load_TLS().
413 * (e.g. xen_load_tls())
415 savesegment(fs, fsindex);
416 savesegment(gs, gsindex);
421 * Leave lazy mode, flushing any hypercalls made here.
422 * This must be done before restoring TLS segments so
423 * the GDT and LDT are properly updated, and must be
424 * done before math_state_restore, so the TS bit is up
427 arch_end_context_switch(next_p);
432 * Segment register != 0 always requires a reload. Also
433 * reload when it has changed. When prev process used 64bit
434 * base always reload to avoid an information leak.
436 if (unlikely(fsindex | next->fsindex | prev->fs)) {
437 loadsegment(fs, next->fsindex);
439 * Check if the user used a selector != 0; if yes
440 * clear 64bit base, since overloaded base is always
441 * mapped to the Null selector
446 /* when next process has a 64bit base use it */
448 wrmsrl(MSR_FS_BASE, next->fs);
449 prev->fsindex = fsindex;
451 if (unlikely(gsindex | next->gsindex | prev->gs)) {
452 load_gs_index(next->gsindex);
457 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
458 prev->gsindex = gsindex;
461 * Switch the PDA and FPU contexts.
463 prev->usersp = percpu_read(old_rsp);
464 percpu_write(old_rsp, next->usersp);
465 percpu_write(current_task, next_p);
467 percpu_write(kernel_stack,
468 (unsigned long)task_stack_page(next_p) +
469 THREAD_SIZE - KERNEL_STACK_OFFSET);
472 * Now maybe reload the debug registers and handle I/O bitmaps
474 if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
475 task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
476 __switch_to_xtra(prev_p, next_p, tss);
481 void set_personality_64bit(void)
483 /* inherit personality from parent */
485 /* Make sure to be in 64bit mode */
486 clear_thread_flag(TIF_IA32);
488 /* Ensure the corresponding mm is not marked. */
490 current->mm->context.ia32_compat = 0;
492 /* TBD: overwrites user setup. Should have two bits.
493 But 64bit processes have always behaved this way,
494 so it's not too bad. The main problem is just that
495 32bit childs are affected again. */
496 current->personality &= ~READ_IMPLIES_EXEC;
499 void set_personality_ia32(void)
501 /* inherit personality from parent */
503 /* Make sure to be in 32bit mode */
504 set_thread_flag(TIF_IA32);
505 current->personality |= force_personality32;
507 /* Mark the associated mm as containing 32-bit tasks. */
509 current->mm->context.ia32_compat = 1;
511 /* Prepare the first "return" to user space */
512 current_thread_info()->status |= TS_COMPAT;
515 unsigned long get_wchan(struct task_struct *p)
521 if (!p || p == current || p->state == TASK_RUNNING)
523 stack = (unsigned long)task_stack_page(p);
524 if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
526 fp = *(u64 *)(p->thread.sp);
528 if (fp < (unsigned long)stack ||
529 fp >= (unsigned long)stack+THREAD_SIZE)
532 if (!in_sched_functions(ip))
535 } while (count++ < 16);
539 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
542 int doit = task == current;
547 if (addr >= TASK_SIZE_OF(task))
550 /* handle small bases via the GDT because that's faster to
552 if (addr <= 0xffffffff) {
553 set_32bit_tls(task, GS_TLS, addr);
555 load_TLS(&task->thread, cpu);
556 load_gs_index(GS_TLS_SEL);
558 task->thread.gsindex = GS_TLS_SEL;
561 task->thread.gsindex = 0;
562 task->thread.gs = addr;
565 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
571 /* Not strictly needed for fs, but do it for symmetry
573 if (addr >= TASK_SIZE_OF(task))
576 /* handle small bases via the GDT because that's faster to
578 if (addr <= 0xffffffff) {
579 set_32bit_tls(task, FS_TLS, addr);
581 load_TLS(&task->thread, cpu);
582 loadsegment(fs, FS_TLS_SEL);
584 task->thread.fsindex = FS_TLS_SEL;
587 task->thread.fsindex = 0;
588 task->thread.fs = addr;
590 /* set the selector to 0 to not confuse
593 ret = checking_wrmsrl(MSR_FS_BASE, addr);
600 if (task->thread.fsindex == FS_TLS_SEL)
601 base = read_32bit_tls(task, FS_TLS);
603 rdmsrl(MSR_FS_BASE, base);
605 base = task->thread.fs;
606 ret = put_user(base, (unsigned long __user *)addr);
612 if (task->thread.gsindex == GS_TLS_SEL)
613 base = read_32bit_tls(task, GS_TLS);
615 savesegment(gs, gsindex);
617 rdmsrl(MSR_KERNEL_GS_BASE, base);
619 base = task->thread.gs;
621 base = task->thread.gs;
622 ret = put_user(base, (unsigned long __user *)addr);
634 long sys_arch_prctl(int code, unsigned long addr)
636 return do_arch_prctl(current, code, addr);
639 unsigned long KSTK_ESP(struct task_struct *task)
641 return (test_tsk_thread_flag(task, TIF_IA32)) ?
642 (task_pt_regs(task)->sp) : ((task)->thread.usersp);