x86: use generic register name in the thread and tss structures
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / arch / x86 / kernel / process_32.c
blobadd3bf34e205051b8ac925e61ef0f5a77e3ac587
1 /*
2 * Copyright (C) 1995 Linus Torvalds
4 * Pentium III FXSR, SSE support
5 * Gareth Hughes <gareth@valinux.com>, May 2000
6 */
8 /*
9 * This file handles the architecture-dependent parts of process handling..
12 #include <stdarg.h>
14 #include <linux/cpu.h>
15 #include <linux/errno.h>
16 #include <linux/sched.h>
17 #include <linux/fs.h>
18 #include <linux/kernel.h>
19 #include <linux/mm.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/a.out.h>
27 #include <linux/interrupt.h>
28 #include <linux/utsname.h>
29 #include <linux/delay.h>
30 #include <linux/reboot.h>
31 #include <linux/init.h>
32 #include <linux/mc146818rtc.h>
33 #include <linux/module.h>
34 #include <linux/kallsyms.h>
35 #include <linux/ptrace.h>
36 #include <linux/random.h>
37 #include <linux/personality.h>
38 #include <linux/tick.h>
39 #include <linux/percpu.h>
41 #include <asm/uaccess.h>
42 #include <asm/pgtable.h>
43 #include <asm/system.h>
44 #include <asm/io.h>
45 #include <asm/ldt.h>
46 #include <asm/processor.h>
47 #include <asm/i387.h>
48 #include <asm/desc.h>
49 #include <asm/vm86.h>
50 #ifdef CONFIG_MATH_EMULATION
51 #include <asm/math_emu.h>
52 #endif
54 #include <linux/err.h>
56 #include <asm/tlbflush.h>
57 #include <asm/cpu.h>
58 #include <asm/kdebug.h>
60 asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
62 static int hlt_counter;
64 unsigned long boot_option_idle_override = 0;
65 EXPORT_SYMBOL(boot_option_idle_override);
67 DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
68 EXPORT_PER_CPU_SYMBOL(current_task);
70 DEFINE_PER_CPU(int, cpu_number);
71 EXPORT_PER_CPU_SYMBOL(cpu_number);
74 * Return saved PC of a blocked thread.
76 unsigned long thread_saved_pc(struct task_struct *tsk)
78 return ((unsigned long *)tsk->thread.sp)[3];
82 * Powermanagement idle function, if any..
84 void (*pm_idle)(void);
85 EXPORT_SYMBOL(pm_idle);
86 static DEFINE_PER_CPU(unsigned int, cpu_idle_state);
88 void disable_hlt(void)
90 hlt_counter++;
93 EXPORT_SYMBOL(disable_hlt);
95 void enable_hlt(void)
97 hlt_counter--;
100 EXPORT_SYMBOL(enable_hlt);
103 * We use this if we don't have any better
104 * idle routine..
106 void default_idle(void)
108 if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
109 current_thread_info()->status &= ~TS_POLLING;
111 * TS_POLLING-cleared state must be visible before we
112 * test NEED_RESCHED:
114 smp_mb();
116 local_irq_disable();
117 if (!need_resched()) {
118 ktime_t t0, t1;
119 u64 t0n, t1n;
121 t0 = ktime_get();
122 t0n = ktime_to_ns(t0);
123 safe_halt(); /* enables interrupts racelessly */
124 local_irq_disable();
125 t1 = ktime_get();
126 t1n = ktime_to_ns(t1);
127 sched_clock_idle_wakeup_event(t1n - t0n);
129 local_irq_enable();
130 current_thread_info()->status |= TS_POLLING;
131 } else {
132 /* loop is done by the caller */
133 cpu_relax();
136 #ifdef CONFIG_APM_MODULE
137 EXPORT_SYMBOL(default_idle);
138 #endif
141 * On SMP it's slightly faster (but much more power-consuming!)
142 * to poll the ->work.need_resched flag instead of waiting for the
143 * cross-CPU IPI to arrive. Use this option with caution.
145 static void poll_idle (void)
147 cpu_relax();
150 #ifdef CONFIG_HOTPLUG_CPU
151 #include <asm/nmi.h>
152 /* We don't actually take CPU down, just spin without interrupts. */
153 static inline void play_dead(void)
155 /* This must be done before dead CPU ack */
156 cpu_exit_clear();
157 wbinvd();
158 mb();
159 /* Ack it */
160 __get_cpu_var(cpu_state) = CPU_DEAD;
163 * With physical CPU hotplug, we should halt the cpu
165 local_irq_disable();
166 while (1)
167 halt();
169 #else
170 static inline void play_dead(void)
172 BUG();
174 #endif /* CONFIG_HOTPLUG_CPU */
177 * The idle thread. There's no useful work to be
178 * done, so just try to conserve power and have a
179 * low exit latency (ie sit in a loop waiting for
180 * somebody to say that they'd like to reschedule)
182 void cpu_idle(void)
184 int cpu = smp_processor_id();
186 current_thread_info()->status |= TS_POLLING;
188 /* endless idle loop with no priority at all */
189 while (1) {
190 tick_nohz_stop_sched_tick();
191 while (!need_resched()) {
192 void (*idle)(void);
194 if (__get_cpu_var(cpu_idle_state))
195 __get_cpu_var(cpu_idle_state) = 0;
197 check_pgt_cache();
198 rmb();
199 idle = pm_idle;
201 if (!idle)
202 idle = default_idle;
204 if (cpu_is_offline(cpu))
205 play_dead();
207 __get_cpu_var(irq_stat).idle_timestamp = jiffies;
208 idle();
210 tick_nohz_restart_sched_tick();
211 preempt_enable_no_resched();
212 schedule();
213 preempt_disable();
217 static void do_nothing(void *unused)
221 void cpu_idle_wait(void)
223 unsigned int cpu, this_cpu = get_cpu();
224 cpumask_t map, tmp = current->cpus_allowed;
226 set_cpus_allowed(current, cpumask_of_cpu(this_cpu));
227 put_cpu();
229 cpus_clear(map);
230 for_each_online_cpu(cpu) {
231 per_cpu(cpu_idle_state, cpu) = 1;
232 cpu_set(cpu, map);
235 __get_cpu_var(cpu_idle_state) = 0;
237 wmb();
238 do {
239 ssleep(1);
240 for_each_online_cpu(cpu) {
241 if (cpu_isset(cpu, map) && !per_cpu(cpu_idle_state, cpu))
242 cpu_clear(cpu, map);
244 cpus_and(map, map, cpu_online_map);
246 * We waited 1 sec, if a CPU still did not call idle
247 * it may be because it is in idle and not waking up
248 * because it has nothing to do.
249 * Give all the remaining CPUS a kick.
251 smp_call_function_mask(map, do_nothing, 0, 0);
252 } while (!cpus_empty(map));
254 set_cpus_allowed(current, tmp);
256 EXPORT_SYMBOL_GPL(cpu_idle_wait);
259 * This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
260 * which can obviate IPI to trigger checking of need_resched.
261 * We execute MONITOR against need_resched and enter optimized wait state
262 * through MWAIT. Whenever someone changes need_resched, we would be woken
263 * up from MWAIT (without an IPI).
265 * New with Core Duo processors, MWAIT can take some hints based on CPU
266 * capability.
268 void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
270 if (!need_resched()) {
271 __monitor((void *)&current_thread_info()->flags, 0, 0);
272 smp_mb();
273 if (!need_resched())
274 __mwait(ax, cx);
278 /* Default MONITOR/MWAIT with no hints, used for default C1 state */
279 static void mwait_idle(void)
281 local_irq_enable();
282 mwait_idle_with_hints(0, 0);
285 void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
287 if (cpu_has(c, X86_FEATURE_MWAIT)) {
288 printk("monitor/mwait feature present.\n");
290 * Skip, if setup has overridden idle.
291 * One CPU supports mwait => All CPUs supports mwait
293 if (!pm_idle) {
294 printk("using mwait in idle threads.\n");
295 pm_idle = mwait_idle;
300 static int __init idle_setup(char *str)
302 if (!strcmp(str, "poll")) {
303 printk("using polling idle threads.\n");
304 pm_idle = poll_idle;
305 #ifdef CONFIG_X86_SMP
306 if (smp_num_siblings > 1)
307 printk("WARNING: polling idle and HT enabled, performance may degrade.\n");
308 #endif
309 } else if (!strcmp(str, "mwait"))
310 force_mwait = 1;
311 else
312 return -1;
314 boot_option_idle_override = 1;
315 return 0;
317 early_param("idle", idle_setup);
319 void __show_registers(struct pt_regs *regs, int all)
321 unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
322 unsigned long d0, d1, d2, d3, d6, d7;
323 unsigned long sp;
324 unsigned short ss, gs;
326 if (user_mode_vm(regs)) {
327 sp = regs->sp;
328 ss = regs->ss & 0xffff;
329 savesegment(gs, gs);
330 } else {
331 sp = (unsigned long) (&regs->sp);
332 savesegment(ss, ss);
333 savesegment(gs, gs);
336 printk("\n");
337 printk("Pid: %d, comm: %s %s (%s %.*s)\n",
338 task_pid_nr(current), current->comm,
339 print_tainted(), init_utsname()->release,
340 (int)strcspn(init_utsname()->version, " "),
341 init_utsname()->version);
343 printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
344 0xffff & regs->cs, regs->ip, regs->flags,
345 smp_processor_id());
346 print_symbol("EIP is at %s\n", regs->ip);
348 printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
349 regs->ax, regs->bx, regs->cx, regs->dx);
350 printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
351 regs->si, regs->di, regs->bp, sp);
352 printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
353 regs->ds & 0xffff, regs->es & 0xffff,
354 regs->fs & 0xffff, gs, ss);
356 if (!all)
357 return;
359 cr0 = read_cr0();
360 cr2 = read_cr2();
361 cr3 = read_cr3();
362 cr4 = read_cr4_safe();
363 printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
364 cr0, cr2, cr3, cr4);
366 get_debugreg(d0, 0);
367 get_debugreg(d1, 1);
368 get_debugreg(d2, 2);
369 get_debugreg(d3, 3);
370 printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
371 d0, d1, d2, d3);
373 get_debugreg(d6, 6);
374 get_debugreg(d7, 7);
375 printk("DR6: %08lx DR7: %08lx\n",
376 d6, d7);
379 void show_regs(struct pt_regs *regs)
381 __show_registers(regs, 1);
382 show_trace(NULL, regs, &regs->sp);
386 * This gets run with %bx containing the
387 * function to call, and %dx containing
388 * the "args".
390 extern void kernel_thread_helper(void);
393 * Create a kernel thread
395 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
397 struct pt_regs regs;
399 memset(&regs, 0, sizeof(regs));
401 regs.bx = (unsigned long) fn;
402 regs.dx = (unsigned long) arg;
404 regs.ds = __USER_DS;
405 regs.es = __USER_DS;
406 regs.fs = __KERNEL_PERCPU;
407 regs.orig_ax = -1;
408 regs.ip = (unsigned long) kernel_thread_helper;
409 regs.cs = __KERNEL_CS | get_kernel_rpl();
410 regs.flags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
412 /* Ok, create the new process.. */
413 return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
415 EXPORT_SYMBOL(kernel_thread);
418 * Free current thread data structures etc..
420 void exit_thread(void)
422 /* The process may have allocated an io port bitmap... nuke it. */
423 if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
424 struct task_struct *tsk = current;
425 struct thread_struct *t = &tsk->thread;
426 int cpu = get_cpu();
427 struct tss_struct *tss = &per_cpu(init_tss, cpu);
429 kfree(t->io_bitmap_ptr);
430 t->io_bitmap_ptr = NULL;
431 clear_thread_flag(TIF_IO_BITMAP);
433 * Careful, clear this in the TSS too:
435 memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
436 t->io_bitmap_max = 0;
437 tss->io_bitmap_owner = NULL;
438 tss->io_bitmap_max = 0;
439 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
440 put_cpu();
444 void flush_thread(void)
446 struct task_struct *tsk = current;
448 tsk->thread.debugreg0 = 0;
449 tsk->thread.debugreg1 = 0;
450 tsk->thread.debugreg2 = 0;
451 tsk->thread.debugreg3 = 0;
452 tsk->thread.debugreg6 = 0;
453 tsk->thread.debugreg7 = 0;
454 memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
455 clear_tsk_thread_flag(tsk, TIF_DEBUG);
457 * Forget coprocessor state..
459 clear_fpu(tsk);
460 clear_used_math();
463 void release_thread(struct task_struct *dead_task)
465 BUG_ON(dead_task->mm);
466 release_vm86_irqs(dead_task);
470 * This gets called before we allocate a new thread and copy
471 * the current task into it.
473 void prepare_to_copy(struct task_struct *tsk)
475 unlazy_fpu(tsk);
478 int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
479 unsigned long unused,
480 struct task_struct * p, struct pt_regs * regs)
482 struct pt_regs * childregs;
483 struct task_struct *tsk;
484 int err;
486 childregs = task_pt_regs(p);
487 *childregs = *regs;
488 childregs->ax = 0;
489 childregs->sp = sp;
491 p->thread.sp = (unsigned long) childregs;
492 p->thread.sp0 = (unsigned long) (childregs+1);
494 p->thread.ip = (unsigned long) ret_from_fork;
496 savesegment(gs,p->thread.gs);
498 tsk = current;
499 if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
500 p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
501 IO_BITMAP_BYTES, GFP_KERNEL);
502 if (!p->thread.io_bitmap_ptr) {
503 p->thread.io_bitmap_max = 0;
504 return -ENOMEM;
506 set_tsk_thread_flag(p, TIF_IO_BITMAP);
509 err = 0;
512 * Set a new TLS for the child thread?
514 if (clone_flags & CLONE_SETTLS)
515 err = do_set_thread_area(p, -1,
516 (struct user_desc __user *)childregs->si, 0);
518 if (err && p->thread.io_bitmap_ptr) {
519 kfree(p->thread.io_bitmap_ptr);
520 p->thread.io_bitmap_max = 0;
522 return err;
526 * fill in the user structure for a core dump..
528 void dump_thread(struct pt_regs * regs, struct user * dump)
530 u16 gs;
532 /* changed the size calculations - should hopefully work better. lbt */
533 dump->magic = CMAGIC;
534 dump->start_code = 0;
535 dump->start_stack = regs->sp & ~(PAGE_SIZE - 1);
536 dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
537 dump->u_dsize = ((unsigned long) (current->mm->brk + (PAGE_SIZE-1))) >> PAGE_SHIFT;
538 dump->u_dsize -= dump->u_tsize;
539 dump->u_ssize = 0;
540 dump->u_debugreg[0] = current->thread.debugreg0;
541 dump->u_debugreg[1] = current->thread.debugreg1;
542 dump->u_debugreg[2] = current->thread.debugreg2;
543 dump->u_debugreg[3] = current->thread.debugreg3;
544 dump->u_debugreg[4] = 0;
545 dump->u_debugreg[5] = 0;
546 dump->u_debugreg[6] = current->thread.debugreg6;
547 dump->u_debugreg[7] = current->thread.debugreg7;
549 if (dump->start_stack < TASK_SIZE)
550 dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
552 dump->regs.bx = regs->bx;
553 dump->regs.cx = regs->cx;
554 dump->regs.dx = regs->dx;
555 dump->regs.si = regs->si;
556 dump->regs.di = regs->di;
557 dump->regs.bp = regs->bp;
558 dump->regs.ax = regs->ax;
559 dump->regs.ds = (u16)regs->ds;
560 dump->regs.es = (u16)regs->es;
561 dump->regs.fs = (u16)regs->fs;
562 savesegment(gs,gs);
563 dump->regs.orig_ax = regs->orig_ax;
564 dump->regs.ip = regs->ip;
565 dump->regs.cs = (u16)regs->cs;
566 dump->regs.flags = regs->flags;
567 dump->regs.sp = regs->sp;
568 dump->regs.ss = (u16)regs->ss;
570 dump->u_fpvalid = dump_fpu (regs, &dump->i387);
572 EXPORT_SYMBOL(dump_thread);
575 * Capture the user space registers if the task is not running (in user space)
577 int dump_task_regs(struct task_struct *tsk, elf_gregset_t *regs)
579 struct pt_regs ptregs = *task_pt_regs(tsk);
580 ptregs.cs &= 0xffff;
581 ptregs.ds &= 0xffff;
582 ptregs.es &= 0xffff;
583 ptregs.ss &= 0xffff;
585 elf_core_copy_regs(regs, &ptregs);
587 return 1;
590 #ifdef CONFIG_SECCOMP
591 void hard_disable_TSC(void)
593 write_cr4(read_cr4() | X86_CR4_TSD);
595 void disable_TSC(void)
597 preempt_disable();
598 if (!test_and_set_thread_flag(TIF_NOTSC))
600 * Must flip the CPU state synchronously with
601 * TIF_NOTSC in the current running context.
603 hard_disable_TSC();
604 preempt_enable();
606 void hard_enable_TSC(void)
608 write_cr4(read_cr4() & ~X86_CR4_TSD);
610 #endif /* CONFIG_SECCOMP */
612 static noinline void
613 __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
614 struct tss_struct *tss)
616 struct thread_struct *prev, *next;
618 prev = &prev_p->thread;
619 next = &next_p->thread;
621 if (next->debugctlmsr != prev->debugctlmsr)
622 wrmsr(MSR_IA32_DEBUGCTLMSR, next->debugctlmsr, 0);
624 if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
625 set_debugreg(next->debugreg0, 0);
626 set_debugreg(next->debugreg1, 1);
627 set_debugreg(next->debugreg2, 2);
628 set_debugreg(next->debugreg3, 3);
629 /* no 4 and 5 */
630 set_debugreg(next->debugreg6, 6);
631 set_debugreg(next->debugreg7, 7);
634 #ifdef CONFIG_SECCOMP
635 if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
636 test_tsk_thread_flag(next_p, TIF_NOTSC)) {
637 /* prev and next are different */
638 if (test_tsk_thread_flag(next_p, TIF_NOTSC))
639 hard_disable_TSC();
640 else
641 hard_enable_TSC();
643 #endif
645 if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
647 * Disable the bitmap via an invalid offset. We still cache
648 * the previous bitmap owner and the IO bitmap contents:
650 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
651 return;
654 if (likely(next == tss->io_bitmap_owner)) {
656 * Previous owner of the bitmap (hence the bitmap content)
657 * matches the next task, we dont have to do anything but
658 * to set a valid offset in the TSS:
660 tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
661 return;
664 * Lazy TSS's I/O bitmap copy. We set an invalid offset here
665 * and we let the task to get a GPF in case an I/O instruction
666 * is performed. The handler of the GPF will verify that the
667 * faulting task has a valid I/O bitmap and, it true, does the
668 * real copy and restart the instruction. This will save us
669 * redundant copies when the currently switched task does not
670 * perform any I/O during its timeslice.
672 tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
676 * switch_to(x,yn) should switch tasks from x to y.
678 * We fsave/fwait so that an exception goes off at the right time
679 * (as a call from the fsave or fwait in effect) rather than to
680 * the wrong process. Lazy FP saving no longer makes any sense
681 * with modern CPU's, and this simplifies a lot of things (SMP
682 * and UP become the same).
684 * NOTE! We used to use the x86 hardware context switching. The
685 * reason for not using it any more becomes apparent when you
686 * try to recover gracefully from saved state that is no longer
687 * valid (stale segment register values in particular). With the
688 * hardware task-switch, there is no way to fix up bad state in
689 * a reasonable manner.
691 * The fact that Intel documents the hardware task-switching to
692 * be slow is a fairly red herring - this code is not noticeably
693 * faster. However, there _is_ some room for improvement here,
694 * so the performance issues may eventually be a valid point.
695 * More important, however, is the fact that this allows us much
696 * more flexibility.
698 * The return value (in %ax) will be the "prev" task after
699 * the task-switch, and shows up in ret_from_fork in entry.S,
700 * for example.
702 struct task_struct fastcall * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
704 struct thread_struct *prev = &prev_p->thread,
705 *next = &next_p->thread;
706 int cpu = smp_processor_id();
707 struct tss_struct *tss = &per_cpu(init_tss, cpu);
709 /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
711 __unlazy_fpu(prev_p);
714 /* we're going to use this soon, after a few expensive things */
715 if (next_p->fpu_counter > 5)
716 prefetch(&next->i387.fxsave);
719 * Reload esp0.
721 load_sp0(tss, next);
724 * Save away %gs. No need to save %fs, as it was saved on the
725 * stack on entry. No need to save %es and %ds, as those are
726 * always kernel segments while inside the kernel. Doing this
727 * before setting the new TLS descriptors avoids the situation
728 * where we temporarily have non-reloadable segments in %fs
729 * and %gs. This could be an issue if the NMI handler ever
730 * used %fs or %gs (it does not today), or if the kernel is
731 * running inside of a hypervisor layer.
733 savesegment(gs, prev->gs);
736 * Load the per-thread Thread-Local Storage descriptor.
738 load_TLS(next, cpu);
741 * Restore IOPL if needed. In normal use, the flags restore
742 * in the switch assembly will handle this. But if the kernel
743 * is running virtualized at a non-zero CPL, the popf will
744 * not restore flags, so it must be done in a separate step.
746 if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
747 set_iopl_mask(next->iopl);
750 * Now maybe handle debug registers and/or IO bitmaps
752 if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
753 task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
754 __switch_to_xtra(prev_p, next_p, tss);
757 * Leave lazy mode, flushing any hypercalls made here.
758 * This must be done before restoring TLS segments so
759 * the GDT and LDT are properly updated, and must be
760 * done before math_state_restore, so the TS bit is up
761 * to date.
763 arch_leave_lazy_cpu_mode();
765 /* If the task has used fpu the last 5 timeslices, just do a full
766 * restore of the math state immediately to avoid the trap; the
767 * chances of needing FPU soon are obviously high now
769 if (next_p->fpu_counter > 5)
770 math_state_restore();
773 * Restore %gs if needed (which is common)
775 if (prev->gs | next->gs)
776 loadsegment(gs, next->gs);
778 x86_write_percpu(current_task, next_p);
780 return prev_p;
783 asmlinkage int sys_fork(struct pt_regs regs)
785 return do_fork(SIGCHLD, regs.sp, &regs, 0, NULL, NULL);
788 asmlinkage int sys_clone(struct pt_regs regs)
790 unsigned long clone_flags;
791 unsigned long newsp;
792 int __user *parent_tidptr, *child_tidptr;
794 clone_flags = regs.bx;
795 newsp = regs.cx;
796 parent_tidptr = (int __user *)regs.dx;
797 child_tidptr = (int __user *)regs.di;
798 if (!newsp)
799 newsp = regs.sp;
800 return do_fork(clone_flags, newsp, &regs, 0, parent_tidptr, child_tidptr);
804 * This is trivial, and on the face of it looks like it
805 * could equally well be done in user mode.
807 * Not so, for quite unobvious reasons - register pressure.
808 * In user mode vfork() cannot have a stack frame, and if
809 * done by calling the "clone()" system call directly, you
810 * do not have enough call-clobbered registers to hold all
811 * the information you need.
813 asmlinkage int sys_vfork(struct pt_regs regs)
815 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, &regs, 0, NULL, NULL);
819 * sys_execve() executes a new program.
821 asmlinkage int sys_execve(struct pt_regs regs)
823 int error;
824 char * filename;
826 filename = getname((char __user *) regs.bx);
827 error = PTR_ERR(filename);
828 if (IS_ERR(filename))
829 goto out;
830 error = do_execve(filename,
831 (char __user * __user *) regs.cx,
832 (char __user * __user *) regs.dx,
833 &regs);
834 if (error == 0) {
835 /* Make sure we don't return using sysenter.. */
836 set_thread_flag(TIF_IRET);
838 putname(filename);
839 out:
840 return error;
843 #define top_esp (THREAD_SIZE - sizeof(unsigned long))
844 #define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
846 unsigned long get_wchan(struct task_struct *p)
848 unsigned long bp, sp, ip;
849 unsigned long stack_page;
850 int count = 0;
851 if (!p || p == current || p->state == TASK_RUNNING)
852 return 0;
853 stack_page = (unsigned long)task_stack_page(p);
854 sp = p->thread.sp;
855 if (!stack_page || sp < stack_page || sp > top_esp+stack_page)
856 return 0;
857 /* include/asm-i386/system.h:switch_to() pushes bp last. */
858 bp = *(unsigned long *) sp;
859 do {
860 if (bp < stack_page || bp > top_ebp+stack_page)
861 return 0;
862 ip = *(unsigned long *) (bp+4);
863 if (!in_sched_functions(ip))
864 return ip;
865 bp = *(unsigned long *) bp;
866 } while (count++ < 16);
867 return 0;
870 unsigned long arch_align_stack(unsigned long sp)
872 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
873 sp -= get_random_int() % 8192;
874 return sp & ~0xf;
877 unsigned long arch_randomize_brk(struct mm_struct *mm)
879 unsigned long range_end = mm->brk + 0x02000000;
880 return randomize_range(mm->brk, range_end, 0) ? : mm->brk;