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_stop_sched_tick(1);
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();
142 if (cpuidle_idle_call())
144 start_critical_timings();
146 /* In many cases the interrupt that ended idle
147 has already called exit_idle. But some idle
148 loops can be woken up without interrupt. */
152 tick_nohz_restart_sched_tick();
153 preempt_enable_no_resched();
159 /* Prints also some state that isn't saved in the pt_regs */
160 void __show_regs(struct pt_regs *regs, int all)
162 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
163 unsigned long d0, d1, d2, d3, d6, d7;
164 unsigned int fsindex, gsindex;
165 unsigned int ds, cs, es;
168 printk(KERN_DEFAULT "RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->ip);
169 printk_address(regs->ip, 1);
170 printk(KERN_DEFAULT "RSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss,
171 regs->sp, regs->flags);
172 printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n",
173 regs->ax, regs->bx, regs->cx);
174 printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n",
175 regs->dx, regs->si, regs->di);
176 printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n",
177 regs->bp, regs->r8, regs->r9);
178 printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n",
179 regs->r10, regs->r11, regs->r12);
180 printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n",
181 regs->r13, regs->r14, regs->r15);
183 asm("movl %%ds,%0" : "=r" (ds));
184 asm("movl %%cs,%0" : "=r" (cs));
185 asm("movl %%es,%0" : "=r" (es));
186 asm("movl %%fs,%0" : "=r" (fsindex));
187 asm("movl %%gs,%0" : "=r" (gsindex));
189 rdmsrl(MSR_FS_BASE, fs);
190 rdmsrl(MSR_GS_BASE, gs);
191 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
201 printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
202 fs, fsindex, gs, gsindex, shadowgs);
203 printk(KERN_DEFAULT "CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds,
205 printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3,
211 printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", d0, d1, d2);
215 printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", d3, d6, d7);
218 void release_thread(struct task_struct *dead_task)
221 if (dead_task->mm->context.size) {
222 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
224 dead_task->mm->context.ldt,
225 dead_task->mm->context.size);
231 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
233 struct user_desc ud = {
240 struct desc_struct *desc = t->thread.tls_array;
245 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
247 return get_desc_base(&t->thread.tls_array[tls]);
251 * This gets called before we allocate a new thread and copy
252 * the current task into it.
254 void prepare_to_copy(struct task_struct *tsk)
259 int copy_thread(unsigned long clone_flags, unsigned long sp,
260 unsigned long unused,
261 struct task_struct *p, struct pt_regs *regs)
264 struct pt_regs *childregs;
265 struct task_struct *me = current;
267 childregs = ((struct pt_regs *)
268 (THREAD_SIZE + task_stack_page(p))) - 1;
275 childregs->sp = (unsigned long)childregs;
277 p->thread.sp = (unsigned long) childregs;
278 p->thread.sp0 = (unsigned long) (childregs+1);
279 p->thread.usersp = me->thread.usersp;
281 set_tsk_thread_flag(p, TIF_FORK);
283 p->thread.io_bitmap_ptr = NULL;
285 savesegment(gs, p->thread.gsindex);
286 p->thread.gs = p->thread.gsindex ? 0 : me->thread.gs;
287 savesegment(fs, p->thread.fsindex);
288 p->thread.fs = p->thread.fsindex ? 0 : me->thread.fs;
289 savesegment(es, p->thread.es);
290 savesegment(ds, p->thread.ds);
293 memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
295 if (unlikely(test_tsk_thread_flag(me, TIF_IO_BITMAP))) {
296 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
297 if (!p->thread.io_bitmap_ptr) {
298 p->thread.io_bitmap_max = 0;
301 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr,
303 set_tsk_thread_flag(p, TIF_IO_BITMAP);
307 * Set a new TLS for the child thread?
309 if (clone_flags & CLONE_SETTLS) {
310 #ifdef CONFIG_IA32_EMULATION
311 if (test_thread_flag(TIF_IA32))
312 err = do_set_thread_area(p, -1,
313 (struct user_desc __user *)childregs->si, 0);
316 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
322 if (err && p->thread.io_bitmap_ptr) {
323 kfree(p->thread.io_bitmap_ptr);
324 p->thread.io_bitmap_max = 0;
331 start_thread_common(struct pt_regs *regs, unsigned long new_ip,
332 unsigned long new_sp,
333 unsigned int _cs, unsigned int _ss, unsigned int _ds)
336 loadsegment(es, _ds);
337 loadsegment(ds, _ds);
341 percpu_write(old_rsp, new_sp);
344 regs->flags = X86_EFLAGS_IF;
346 * Free the old FP and other extended state
348 free_thread_xstate(current);
352 start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
354 start_thread_common(regs, new_ip, new_sp,
355 __USER_CS, __USER_DS, 0);
358 #ifdef CONFIG_IA32_EMULATION
359 void start_thread_ia32(struct pt_regs *regs, u32 new_ip, u32 new_sp)
361 start_thread_common(regs, new_ip, new_sp,
362 __USER32_CS, __USER32_DS, __USER32_DS);
367 * switch_to(x,y) should switch tasks from x to y.
369 * This could still be optimized:
370 * - fold all the options into a flag word and test it with a single test.
371 * - could test fs/gs bitsliced
373 * Kprobes not supported here. Set the probe on schedule instead.
374 * Function graph tracer not supported too.
376 __notrace_funcgraph struct task_struct *
377 __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
379 struct thread_struct *prev = &prev_p->thread;
380 struct thread_struct *next = &next_p->thread;
381 int cpu = smp_processor_id();
382 struct tss_struct *tss = &per_cpu(init_tss, cpu);
383 unsigned fsindex, gsindex;
385 __unlazy_fpu(prev_p);
388 * Reload esp0, LDT and the page table pointer:
394 * This won't pick up thread selector changes, but I guess that is ok.
396 savesegment(es, prev->es);
397 if (unlikely(next->es | prev->es))
398 loadsegment(es, next->es);
400 savesegment(ds, prev->ds);
401 if (unlikely(next->ds | prev->ds))
402 loadsegment(ds, next->ds);
405 /* We must save %fs and %gs before load_TLS() because
406 * %fs and %gs may be cleared by load_TLS().
408 * (e.g. xen_load_tls())
410 savesegment(fs, fsindex);
411 savesegment(gs, gsindex);
416 * Leave lazy mode, flushing any hypercalls made here.
417 * This must be done before restoring TLS segments so
418 * the GDT and LDT are properly updated, and must be
419 * done before math_state_restore, so the TS bit is up
422 arch_end_context_switch(next_p);
427 * Segment register != 0 always requires a reload. Also
428 * reload when it has changed. When prev process used 64bit
429 * base always reload to avoid an information leak.
431 if (unlikely(fsindex | next->fsindex | prev->fs)) {
432 loadsegment(fs, next->fsindex);
434 * Check if the user used a selector != 0; if yes
435 * clear 64bit base, since overloaded base is always
436 * mapped to the Null selector
441 /* when next process has a 64bit base use it */
443 wrmsrl(MSR_FS_BASE, next->fs);
444 prev->fsindex = fsindex;
446 if (unlikely(gsindex | next->gsindex | prev->gs)) {
447 load_gs_index(next->gsindex);
452 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
453 prev->gsindex = gsindex;
456 * Switch the PDA and FPU contexts.
458 prev->usersp = percpu_read(old_rsp);
459 percpu_write(old_rsp, next->usersp);
460 percpu_write(current_task, next_p);
462 percpu_write(kernel_stack,
463 (unsigned long)task_stack_page(next_p) +
464 THREAD_SIZE - KERNEL_STACK_OFFSET);
467 * Now maybe reload the debug registers and handle I/O bitmaps
469 if (unlikely(task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT ||
470 task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV))
471 __switch_to_xtra(prev_p, next_p, tss);
476 void set_personality_64bit(void)
478 /* inherit personality from parent */
480 /* Make sure to be in 64bit mode */
481 clear_thread_flag(TIF_IA32);
483 /* Ensure the corresponding mm is not marked. */
485 current->mm->context.ia32_compat = 0;
487 /* TBD: overwrites user setup. Should have two bits.
488 But 64bit processes have always behaved this way,
489 so it's not too bad. The main problem is just that
490 32bit childs are affected again. */
491 current->personality &= ~READ_IMPLIES_EXEC;
494 void set_personality_ia32(void)
496 /* inherit personality from parent */
498 /* Make sure to be in 32bit mode */
499 set_thread_flag(TIF_IA32);
500 current->personality |= force_personality32;
502 /* Mark the associated mm as containing 32-bit tasks. */
504 current->mm->context.ia32_compat = 1;
506 /* Prepare the first "return" to user space */
507 current_thread_info()->status |= TS_COMPAT;
510 unsigned long get_wchan(struct task_struct *p)
516 if (!p || p == current || p->state == TASK_RUNNING)
518 stack = (unsigned long)task_stack_page(p);
519 if (p->thread.sp < stack || p->thread.sp >= stack+THREAD_SIZE)
521 fp = *(u64 *)(p->thread.sp);
523 if (fp < (unsigned long)stack ||
524 fp >= (unsigned long)stack+THREAD_SIZE)
527 if (!in_sched_functions(ip))
530 } while (count++ < 16);
534 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
537 int doit = task == current;
542 if (addr >= TASK_SIZE_OF(task))
545 /* handle small bases via the GDT because that's faster to
547 if (addr <= 0xffffffff) {
548 set_32bit_tls(task, GS_TLS, addr);
550 load_TLS(&task->thread, cpu);
551 load_gs_index(GS_TLS_SEL);
553 task->thread.gsindex = GS_TLS_SEL;
556 task->thread.gsindex = 0;
557 task->thread.gs = addr;
560 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
566 /* Not strictly needed for fs, but do it for symmetry
568 if (addr >= TASK_SIZE_OF(task))
571 /* handle small bases via the GDT because that's faster to
573 if (addr <= 0xffffffff) {
574 set_32bit_tls(task, FS_TLS, addr);
576 load_TLS(&task->thread, cpu);
577 loadsegment(fs, FS_TLS_SEL);
579 task->thread.fsindex = FS_TLS_SEL;
582 task->thread.fsindex = 0;
583 task->thread.fs = addr;
585 /* set the selector to 0 to not confuse
588 ret = checking_wrmsrl(MSR_FS_BASE, addr);
595 if (task->thread.fsindex == FS_TLS_SEL)
596 base = read_32bit_tls(task, FS_TLS);
598 rdmsrl(MSR_FS_BASE, base);
600 base = task->thread.fs;
601 ret = put_user(base, (unsigned long __user *)addr);
607 if (task->thread.gsindex == GS_TLS_SEL)
608 base = read_32bit_tls(task, GS_TLS);
610 savesegment(gs, gsindex);
612 rdmsrl(MSR_KERNEL_GS_BASE, base);
614 base = task->thread.gs;
616 base = task->thread.gs;
617 ret = put_user(base, (unsigned long __user *)addr);
629 long sys_arch_prctl(int code, unsigned long addr)
631 return do_arch_prctl(current, code, addr);
634 unsigned long KSTK_ESP(struct task_struct *task)
636 return (test_tsk_thread_flag(task, TIF_IA32)) ?
637 (task_pt_regs(task)->sp) : ((task)->thread.usersp);