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 * $Id: process.c,v 1.38 2002/01/15 10:08:03 ak Exp $
16 * This file handles the architecture-dependent parts of process handling..
21 #include <linux/errno.h>
22 #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/module.h>
30 #include <linux/a.out.h>
31 #include <linux/interrupt.h>
32 #include <linux/delay.h>
33 #include <linux/irq.h>
34 #include <linux/ptrace.h>
35 #include <linux/version.h>
37 #include <asm/uaccess.h>
38 #include <asm/pgtable.h>
39 #include <asm/system.h>
41 #include <asm/processor.h>
43 #include <asm/mmu_context.h>
45 #include <asm/prctl.h>
46 #include <asm/kdebug.h>
48 #include <asm/proto.h>
51 asmlinkage extern void ret_from_fork(void);
53 unsigned long kernel_thread_flags = CLONE_VM | CLONE_UNTRACED;
55 atomic_t hlt_counter = ATOMIC_INIT(0);
57 unsigned long boot_option_idle_override = 0;
58 EXPORT_SYMBOL(boot_option_idle_override);
61 * Powermanagement idle function, if any..
63 void (*pm_idle)(void);
64 static cpumask_t cpu_idle_map;
66 void disable_hlt(void)
68 atomic_inc(&hlt_counter);
71 EXPORT_SYMBOL(disable_hlt);
75 atomic_dec(&hlt_counter);
78 EXPORT_SYMBOL(enable_hlt);
81 * We use this if we don't have any better
84 void default_idle(void)
86 if (!atomic_read(&hlt_counter)) {
96 * On SMP it's slightly faster (but much more power-consuming!)
97 * to poll the ->need_resched flag instead of waiting for the
98 * cross-CPU IPI to arrive. Use this option with caution.
100 static void poll_idle (void)
107 * Deal with another CPU just having chosen a thread to
110 oldval = test_and_clear_thread_flag(TIF_NEED_RESCHED);
113 set_thread_flag(TIF_POLLING_NRFLAG);
120 "i" (_TIF_NEED_RESCHED),
121 "m" (current_thread_info()->flags));
128 void cpu_idle_wait(void)
133 for_each_online_cpu(cpu)
134 cpu_set(cpu, cpu_idle_map);
139 cpus_and(map, cpu_idle_map, cpu_online_map);
140 } while (!cpus_empty(map));
142 EXPORT_SYMBOL_GPL(cpu_idle_wait);
145 * The idle thread. There's no useful work to be
146 * done, so just try to conserve power and have a
147 * low exit latency (ie sit in a loop waiting for
148 * somebody to say that they'd like to reschedule)
152 int cpu = smp_processor_id();
154 /* endless idle loop with no priority at all */
156 while (!need_resched()) {
159 if (cpu_isset(cpu, cpu_idle_map))
160 cpu_clear(cpu, cpu_idle_map);
172 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
173 * which can obviate IPI to trigger checking of need_resched.
174 * We execute MONITOR against need_resched and enter optimized wait state
175 * through MWAIT. Whenever someone changes need_resched, we would be woken
176 * up from MWAIT (without an IPI).
178 static void mwait_idle(void)
182 if (!need_resched()) {
183 set_thread_flag(TIF_POLLING_NRFLAG);
185 __monitor((void *)¤t_thread_info()->flags, 0, 0);
189 } while (!need_resched());
190 clear_thread_flag(TIF_POLLING_NRFLAG);
194 void __init select_idle_routine(const struct cpuinfo_x86 *c)
197 if (cpu_has(c, X86_FEATURE_MWAIT)) {
199 * Skip, if setup has overridden idle.
200 * One CPU supports mwait => All CPUs supports mwait
204 printk("using mwait in idle threads.\n");
207 pm_idle = mwait_idle;
212 static int __init idle_setup (char *str)
214 if (!strncmp(str, "poll", 4)) {
215 printk("using polling idle threads.\n");
219 boot_option_idle_override = 1;
223 __setup("idle=", idle_setup);
225 /* Prints also some state that isn't saved in the pt_regs */
226 void __show_regs(struct pt_regs * regs)
228 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs;
229 unsigned int fsindex,gsindex;
230 unsigned int ds,cs,es;
234 printk("Pid: %d, comm: %.20s %s %s\n",
235 current->pid, current->comm, print_tainted(), UTS_RELEASE);
236 printk("RIP: %04lx:[<%016lx>] ", regs->cs & 0xffff, regs->rip);
237 printk_address(regs->rip);
238 printk("\nRSP: %04lx:%016lx EFLAGS: %08lx\n", regs->ss, regs->rsp, regs->eflags);
239 printk("RAX: %016lx RBX: %016lx RCX: %016lx\n",
240 regs->rax, regs->rbx, regs->rcx);
241 printk("RDX: %016lx RSI: %016lx RDI: %016lx\n",
242 regs->rdx, regs->rsi, regs->rdi);
243 printk("RBP: %016lx R08: %016lx R09: %016lx\n",
244 regs->rbp, regs->r8, regs->r9);
245 printk("R10: %016lx R11: %016lx R12: %016lx\n",
246 regs->r10, regs->r11, regs->r12);
247 printk("R13: %016lx R14: %016lx R15: %016lx\n",
248 regs->r13, regs->r14, regs->r15);
250 asm("movl %%ds,%0" : "=r" (ds));
251 asm("movl %%cs,%0" : "=r" (cs));
252 asm("movl %%es,%0" : "=r" (es));
253 asm("movl %%fs,%0" : "=r" (fsindex));
254 asm("movl %%gs,%0" : "=r" (gsindex));
256 rdmsrl(MSR_FS_BASE, fs);
257 rdmsrl(MSR_GS_BASE, gs);
258 rdmsrl(MSR_KERNEL_GS_BASE, shadowgs);
260 asm("movq %%cr0, %0": "=r" (cr0));
261 asm("movq %%cr2, %0": "=r" (cr2));
262 asm("movq %%cr3, %0": "=r" (cr3));
263 asm("movq %%cr4, %0": "=r" (cr4));
265 printk("FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
266 fs,fsindex,gs,gsindex,shadowgs);
267 printk("CS: %04x DS: %04x ES: %04x CR0: %016lx\n", cs, ds, es, cr0);
268 printk("CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, cr4);
271 void show_regs(struct pt_regs *regs)
274 show_trace(®s->rsp);
278 * Free current thread data structures etc..
280 void exit_thread(void)
282 struct task_struct *me = current;
283 struct thread_struct *t = &me->thread;
284 if (me->thread.io_bitmap_ptr) {
285 struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
287 kfree(t->io_bitmap_ptr);
288 t->io_bitmap_ptr = NULL;
290 * Careful, clear this in the TSS too:
292 memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
293 t->io_bitmap_max = 0;
298 void flush_thread(void)
300 struct task_struct *tsk = current;
301 struct thread_info *t = current_thread_info();
303 if (t->flags & _TIF_ABI_PENDING)
304 t->flags ^= (_TIF_ABI_PENDING | _TIF_IA32);
306 tsk->thread.debugreg0 = 0;
307 tsk->thread.debugreg1 = 0;
308 tsk->thread.debugreg2 = 0;
309 tsk->thread.debugreg3 = 0;
310 tsk->thread.debugreg6 = 0;
311 tsk->thread.debugreg7 = 0;
312 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
314 * Forget coprocessor state..
320 void release_thread(struct task_struct *dead_task)
323 if (dead_task->mm->context.size) {
324 printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
326 dead_task->mm->context.ldt,
327 dead_task->mm->context.size);
333 static inline void set_32bit_tls(struct task_struct *t, int tls, u32 addr)
335 struct user_desc ud = {
342 struct n_desc_struct *desc = (void *)t->thread.tls_array;
344 desc->a = LDT_entry_a(&ud);
345 desc->b = LDT_entry_b(&ud);
348 static inline u32 read_32bit_tls(struct task_struct *t, int tls)
350 struct desc_struct *desc = (void *)t->thread.tls_array;
353 (((u32)desc->base1) << 16) |
354 (((u32)desc->base2) << 24);
358 * This gets called before we allocate a new thread and copy
359 * the current task into it.
361 void prepare_to_copy(struct task_struct *tsk)
366 int copy_thread(int nr, unsigned long clone_flags, unsigned long rsp,
367 unsigned long unused,
368 struct task_struct * p, struct pt_regs * regs)
371 struct pt_regs * childregs;
372 struct task_struct *me = current;
374 childregs = ((struct pt_regs *) (THREAD_SIZE + (unsigned long) p->thread_info)) - 1;
379 childregs->rsp = rsp;
381 childregs->rsp = (unsigned long)childregs;
384 p->thread.rsp = (unsigned long) childregs;
385 p->thread.rsp0 = (unsigned long) (childregs+1);
386 p->thread.userrsp = me->thread.userrsp;
388 set_ti_thread_flag(p->thread_info, TIF_FORK);
390 p->thread.fs = me->thread.fs;
391 p->thread.gs = me->thread.gs;
393 asm("movl %%gs,%0" : "=m" (p->thread.gsindex));
394 asm("movl %%fs,%0" : "=m" (p->thread.fsindex));
395 asm("movl %%es,%0" : "=m" (p->thread.es));
396 asm("movl %%ds,%0" : "=m" (p->thread.ds));
398 if (unlikely(me->thread.io_bitmap_ptr != NULL)) {
399 p->thread.io_bitmap_ptr = kmalloc(IO_BITMAP_BYTES, GFP_KERNEL);
400 if (!p->thread.io_bitmap_ptr) {
401 p->thread.io_bitmap_max = 0;
404 memcpy(p->thread.io_bitmap_ptr, me->thread.io_bitmap_ptr, IO_BITMAP_BYTES);
408 * Set a new TLS for the child thread?
410 if (clone_flags & CLONE_SETTLS) {
411 #ifdef CONFIG_IA32_EMULATION
412 if (test_thread_flag(TIF_IA32))
413 err = ia32_child_tls(p, childregs);
416 err = do_arch_prctl(p, ARCH_SET_FS, childregs->r8);
422 if (err && p->thread.io_bitmap_ptr) {
423 kfree(p->thread.io_bitmap_ptr);
424 p->thread.io_bitmap_max = 0;
430 * This special macro can be used to load a debugging register
432 #define loaddebug(thread,r) set_debug(thread->debugreg ## r, r)
435 * switch_to(x,y) should switch tasks from x to y.
437 * This could still be optimized:
438 * - fold all the options into a flag word and test it with a single test.
439 * - could test fs/gs bitsliced
441 struct task_struct *__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
443 struct thread_struct *prev = &prev_p->thread,
444 *next = &next_p->thread;
445 int cpu = smp_processor_id();
446 struct tss_struct *tss = &per_cpu(init_tss, cpu);
451 * Reload esp0, LDT and the page table pointer:
453 tss->rsp0 = next->rsp0;
457 * This won't pick up thread selector changes, but I guess that is ok.
459 asm volatile("movl %%es,%0" : "=m" (prev->es));
460 if (unlikely(next->es | prev->es))
461 loadsegment(es, next->es);
463 asm volatile ("movl %%ds,%0" : "=m" (prev->ds));
464 if (unlikely(next->ds | prev->ds))
465 loadsegment(ds, next->ds);
474 asm volatile("movl %%fs,%0" : "=g" (fsindex));
475 /* segment register != 0 always requires a reload.
476 also reload when it has changed.
477 when prev process used 64bit base always reload
478 to avoid an information leak. */
479 if (unlikely(fsindex | next->fsindex | prev->fs)) {
480 loadsegment(fs, next->fsindex);
481 /* check if the user used a selector != 0
482 * if yes clear 64bit base, since overloaded base
483 * is always mapped to the Null selector
488 /* when next process has a 64bit base use it */
490 wrmsrl(MSR_FS_BASE, next->fs);
491 prev->fsindex = fsindex;
495 asm volatile("movl %%gs,%0" : "=g" (gsindex));
496 if (unlikely(gsindex | next->gsindex | prev->gs)) {
497 load_gs_index(next->gsindex);
502 wrmsrl(MSR_KERNEL_GS_BASE, next->gs);
503 prev->gsindex = gsindex;
507 * Switch the PDA context.
509 prev->userrsp = read_pda(oldrsp);
510 write_pda(oldrsp, next->userrsp);
511 write_pda(pcurrent, next_p);
512 write_pda(kernelstack, (unsigned long)next_p->thread_info + THREAD_SIZE - PDA_STACKOFFSET);
515 * Now maybe reload the debug registers
517 if (unlikely(next->debugreg7)) {
529 * Handle the IO bitmap
531 if (unlikely(prev->io_bitmap_ptr || next->io_bitmap_ptr)) {
532 if (next->io_bitmap_ptr)
534 * Copy the relevant range of the IO bitmap.
535 * Normally this is 128 bytes or less:
537 memcpy(tss->io_bitmap, next->io_bitmap_ptr,
538 max(prev->io_bitmap_max, next->io_bitmap_max));
541 * Clear any possible leftover bits:
543 memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
551 * sys_execve() executes a new program.
554 long sys_execve(char __user *name, char __user * __user *argv,
555 char __user * __user *envp, struct pt_regs regs)
560 filename = getname(name);
561 error = PTR_ERR(filename);
562 if (IS_ERR(filename))
564 error = do_execve(filename, argv, envp, ®s);
567 current->ptrace &= ~PT_DTRACE;
568 task_unlock(current);
574 void set_personality_64bit(void)
576 /* inherit personality from parent */
578 /* Make sure to be in 64bit mode */
579 clear_thread_flag(TIF_IA32);
582 asmlinkage long sys_fork(struct pt_regs *regs)
584 return do_fork(SIGCHLD, regs->rsp, regs, 0, NULL, NULL);
587 asmlinkage long sys_clone(unsigned long clone_flags, unsigned long newsp, void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
591 return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
595 * This is trivial, and on the face of it looks like it
596 * could equally well be done in user mode.
598 * Not so, for quite unobvious reasons - register pressure.
599 * In user mode vfork() cannot have a stack frame, and if
600 * done by calling the "clone()" system call directly, you
601 * do not have enough call-clobbered registers to hold all
602 * the information you need.
604 asmlinkage long sys_vfork(struct pt_regs *regs)
606 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->rsp, regs, 0,
610 unsigned long get_wchan(struct task_struct *p)
616 if (!p || p == current || p->state==TASK_RUNNING)
618 stack = (unsigned long)p->thread_info;
619 if (p->thread.rsp < stack || p->thread.rsp > stack+THREAD_SIZE)
621 fp = *(u64 *)(p->thread.rsp);
623 if (fp < (unsigned long)stack || fp > (unsigned long)stack+THREAD_SIZE)
625 rip = *(u64 *)(fp+8);
626 if (!in_sched_functions(rip))
629 } while (count++ < 16);
633 long do_arch_prctl(struct task_struct *task, int code, unsigned long addr)
636 int doit = task == current;
641 if (addr >= TASK_SIZE)
644 /* handle small bases via the GDT because that's faster to
646 if (addr <= 0xffffffff) {
647 set_32bit_tls(task, GS_TLS, addr);
649 load_TLS(&task->thread, cpu);
650 load_gs_index(GS_TLS_SEL);
652 task->thread.gsindex = GS_TLS_SEL;
655 task->thread.gsindex = 0;
656 task->thread.gs = addr;
659 ret = checking_wrmsrl(MSR_KERNEL_GS_BASE, addr);
665 /* Not strictly needed for fs, but do it for symmetry
667 if (addr >= TASK_SIZE)
670 /* handle small bases via the GDT because that's faster to
672 if (addr <= 0xffffffff) {
673 set_32bit_tls(task, FS_TLS, addr);
675 load_TLS(&task->thread, cpu);
676 asm volatile("movl %0,%%fs" :: "r" (FS_TLS_SEL));
678 task->thread.fsindex = FS_TLS_SEL;
681 task->thread.fsindex = 0;
682 task->thread.fs = addr;
684 /* set the selector to 0 to not confuse
686 asm volatile("movl %0,%%fs" :: "r" (0));
687 ret = checking_wrmsrl(MSR_FS_BASE, addr);
694 if (task->thread.fsindex == FS_TLS_SEL)
695 base = read_32bit_tls(task, FS_TLS);
697 rdmsrl(MSR_FS_BASE, base);
699 base = task->thread.fs;
700 ret = put_user(base, (unsigned long __user *)addr);
705 if (task->thread.gsindex == GS_TLS_SEL)
706 base = read_32bit_tls(task, GS_TLS);
708 rdmsrl(MSR_KERNEL_GS_BASE, base);
710 base = task->thread.gs;
711 ret = put_user(base, (unsigned long __user *)addr);
723 long sys_arch_prctl(int code, unsigned long addr)
725 return do_arch_prctl(current, code, addr);
729 * Capture the user space registers if the task is not running (in user space)
731 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
733 struct pt_regs *pp, ptregs;
735 pp = (struct pt_regs *)(tsk->thread.rsp0);
742 elf_core_copy_regs(regs, &ptregs);