2005-04-17 06:20:36 +08:00
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/*
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* Copyright (C) 1995 Linus Torvalds
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*
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* Pentium III FXSR, SSE support
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* Gareth Hughes <gareth@valinux.com>, May 2000
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*/
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/*
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* This file handles the architecture-dependent parts of process handling..
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*/
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#include <stdarg.h>
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2009-02-11 15:31:00 +08:00
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#include <linux/stackprotector.h>
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2005-06-26 05:54:50 +08:00
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#include <linux/cpu.h>
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2005-04-17 06:20:36 +08:00
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/fs.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/elfcore.h>
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#include <linux/smp.h>
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#include <linux/stddef.h>
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#include <linux/slab.h>
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#include <linux/vmalloc.h>
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#include <linux/user.h>
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#include <linux/interrupt.h>
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#include <linux/utsname.h>
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#include <linux/delay.h>
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#include <linux/reboot.h>
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#include <linux/init.h>
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#include <linux/mc146818rtc.h>
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#include <linux/module.h>
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#include <linux/kallsyms.h>
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#include <linux/ptrace.h>
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#include <linux/random.h>
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2006-09-26 16:52:28 +08:00
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#include <linux/personality.h>
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2007-02-16 17:28:07 +08:00
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#include <linux/tick.h>
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2007-05-03 01:27:16 +08:00
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#include <linux/percpu.h>
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2008-04-14 06:24:18 +08:00
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#include <linux/prctl.h>
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2008-09-17 02:27:30 +08:00
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#include <linux/dmi.h>
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2008-12-06 10:40:00 +08:00
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#include <linux/ftrace.h>
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2009-01-04 18:48:56 +08:00
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#include <linux/uaccess.h>
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#include <linux/io.h>
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#include <linux/kdebug.h>
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2005-04-17 06:20:36 +08:00
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#include <asm/pgtable.h>
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#include <asm/system.h>
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#include <asm/ldt.h>
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#include <asm/processor.h>
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#include <asm/i387.h>
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#include <asm/desc.h>
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#ifdef CONFIG_MATH_EMULATION
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#include <asm/math_emu.h>
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#endif
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#include <linux/err.h>
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2005-06-26 05:54:50 +08:00
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#include <asm/tlbflush.h>
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#include <asm/cpu.h>
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2008-09-24 10:40:02 +08:00
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#include <asm/idle.h>
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2008-07-22 00:04:13 +08:00
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#include <asm/syscalls.h>
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2008-12-19 22:10:24 +08:00
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#include <asm/ds.h>
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2005-06-26 05:54:50 +08:00
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2005-04-17 06:20:36 +08:00
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asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
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2007-05-03 01:27:16 +08:00
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DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task;
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EXPORT_PER_CPU_SYMBOL(current_task);
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2005-04-17 06:20:36 +08:00
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/*
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* Return saved PC of a blocked thread.
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*/
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unsigned long thread_saved_pc(struct task_struct *tsk)
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{
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2008-01-30 20:31:02 +08:00
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return ((unsigned long *)tsk->thread.sp)[3];
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2005-04-17 06:20:36 +08:00
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}
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2008-09-03 21:30:23 +08:00
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#ifndef CONFIG_SMP
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static inline void play_dead(void)
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{
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BUG();
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}
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#endif
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2005-04-17 06:20:36 +08:00
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/*
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* The idle thread. There's no useful work to be
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* done, so just try to conserve power and have a
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* low exit latency (ie sit in a loop waiting for
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* somebody to say that they'd like to reschedule)
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*/
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2005-06-26 05:54:50 +08:00
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void cpu_idle(void)
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2005-04-17 06:20:36 +08:00
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{
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2005-11-09 13:39:01 +08:00
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int cpu = smp_processor_id();
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2005-06-26 05:54:50 +08:00
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2009-02-11 15:31:00 +08:00
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/*
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* If we're the non-boot CPU, nothing set the stack canary up
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* for us. CPU0 already has it initialized but no harm in
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* doing it again. This is a good place for updating it, as
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* we wont ever return from this function (so the invalid
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* canaries already on the stack wont ever trigger).
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*/
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boot_init_stack_canary();
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2006-06-26 19:59:11 +08:00
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current_thread_info()->status |= TS_POLLING;
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[PATCH] sched: resched and cpu_idle rework
Make some changes to the NEED_RESCHED and POLLING_NRFLAG to reduce
confusion, and make their semantics rigid. Improves efficiency of
resched_task and some cpu_idle routines.
* In resched_task:
- TIF_NEED_RESCHED is only cleared with the task's runqueue lock held,
and as we hold it during resched_task, then there is no need for an
atomic test and set there. The only other time this should be set is
when the task's quantum expires, in the timer interrupt - this is
protected against because the rq lock is irq-safe.
- If TIF_NEED_RESCHED is set, then we don't need to do anything. It
won't get unset until the task get's schedule()d off.
- If we are running on the same CPU as the task we resched, then set
TIF_NEED_RESCHED and no further action is required.
- If we are running on another CPU, and TIF_POLLING_NRFLAG is *not* set
after TIF_NEED_RESCHED has been set, then we need to send an IPI.
Using these rules, we are able to remove the test and set operation in
resched_task, and make clear the previously vague semantics of
POLLING_NRFLAG.
* In idle routines:
- Enter cpu_idle with preempt disabled. When the need_resched() condition
becomes true, explicitly call schedule(). This makes things a bit clearer
(IMO), but haven't updated all architectures yet.
- Many do a test and clear of TIF_NEED_RESCHED for some reason. According
to the resched_task rules, this isn't needed (and actually breaks the
assumption that TIF_NEED_RESCHED is only cleared with the runqueue lock
held). So remove that. Generally one less locked memory op when switching
to the idle thread.
- Many idle routines clear TIF_POLLING_NRFLAG, and only set it in the inner
most polling idle loops. The above resched_task semantics allow it to be
set until before the last time need_resched() is checked before going into
a halt requiring interrupt wakeup.
Many idle routines simply never enter such a halt, and so POLLING_NRFLAG
can be always left set, completely eliminating resched IPIs when rescheduling
the idle task.
POLLING_NRFLAG width can be increased, to reduce the chance of resched IPIs.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Con Kolivas <kernel@kolivas.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-09 13:39:04 +08:00
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2005-04-17 06:20:36 +08:00
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/* endless idle loop with no priority at all */
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while (1) {
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2008-07-18 23:27:28 +08:00
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tick_nohz_stop_sched_tick(1);
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2005-04-17 06:20:36 +08:00
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while (!need_resched()) {
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2007-05-13 02:15:24 +08:00
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check_pgt_cache();
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2005-04-17 06:20:36 +08:00
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rmb();
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2008-01-30 20:33:13 +08:00
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if (rcu_pending(cpu))
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rcu_check_callbacks(cpu, 0);
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2005-06-26 05:54:50 +08:00
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if (cpu_is_offline(cpu))
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play_dead();
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2008-04-25 23:39:01 +08:00
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local_irq_disable();
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2008-05-13 03:20:42 +08:00
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/* Don't trace irqs off for idle */
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stop_critical_timings();
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2008-06-09 22:59:53 +08:00
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pm_idle();
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2008-05-13 03:20:42 +08:00
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start_critical_timings();
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2005-04-17 06:20:36 +08:00
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}
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2007-02-16 17:28:07 +08:00
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tick_nohz_restart_sched_tick();
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2005-11-09 13:39:01 +08:00
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preempt_enable_no_resched();
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2005-04-17 06:20:36 +08:00
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schedule();
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2005-11-09 13:39:01 +08:00
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preempt_disable();
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2005-04-17 06:20:36 +08:00
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}
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}
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2008-04-03 21:40:48 +08:00
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void __show_regs(struct pt_regs *regs, int all)
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2005-04-17 06:20:36 +08:00
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{
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unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
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2007-07-21 23:10:42 +08:00
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unsigned long d0, d1, d2, d3, d6, d7;
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2008-01-30 20:30:56 +08:00
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unsigned long sp;
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2007-10-20 02:35:03 +08:00
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unsigned short ss, gs;
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2008-09-17 02:27:30 +08:00
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const char *board;
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2007-10-20 02:35:03 +08:00
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if (user_mode_vm(regs)) {
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2008-01-30 20:30:56 +08:00
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sp = regs->sp;
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ss = regs->ss & 0xffff;
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2009-02-09 21:17:40 +08:00
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gs = get_user_gs(regs);
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2007-10-20 02:35:03 +08:00
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} else {
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2008-01-30 20:30:56 +08:00
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sp = (unsigned long) (®s->sp);
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2007-10-20 02:35:03 +08:00
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savesegment(ss, ss);
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savesegment(gs, gs);
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}
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2005-04-17 06:20:36 +08:00
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printk("\n");
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2008-09-17 02:27:30 +08:00
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board = dmi_get_system_info(DMI_PRODUCT_NAME);
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if (!board)
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board = "";
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printk("Pid: %d, comm: %s %s (%s %.*s) %s\n",
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2007-10-20 06:06:00 +08:00
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task_pid_nr(current), current->comm,
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2007-10-20 02:35:03 +08:00
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print_tainted(), init_utsname()->release,
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(int)strcspn(init_utsname()->version, " "),
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2008-09-17 02:27:30 +08:00
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init_utsname()->version, board);
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2007-10-20 02:35:03 +08:00
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printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
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2008-02-09 04:09:56 +08:00
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(u16)regs->cs, regs->ip, regs->flags,
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2007-10-20 02:35:03 +08:00
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smp_processor_id());
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2008-01-30 20:30:56 +08:00
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print_symbol("EIP is at %s\n", regs->ip);
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2005-04-17 06:20:36 +08:00
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printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
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2008-01-30 20:30:56 +08:00
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regs->ax, regs->bx, regs->cx, regs->dx);
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2007-10-20 02:35:03 +08:00
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printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
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2008-01-30 20:30:56 +08:00
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regs->si, regs->di, regs->bp, sp);
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2007-10-20 02:35:03 +08:00
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printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
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2008-02-09 04:09:56 +08:00
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(u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss);
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2007-10-20 02:35:03 +08:00
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if (!all)
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return;
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2005-04-17 06:20:36 +08:00
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2005-09-04 06:56:36 +08:00
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cr0 = read_cr0();
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cr2 = read_cr2();
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cr3 = read_cr3();
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2006-01-06 16:11:50 +08:00
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cr4 = read_cr4_safe();
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2007-10-20 02:35:03 +08:00
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printk("CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
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cr0, cr2, cr3, cr4);
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2007-07-21 23:10:42 +08:00
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get_debugreg(d0, 0);
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get_debugreg(d1, 1);
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get_debugreg(d2, 2);
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get_debugreg(d3, 3);
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printk("DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n",
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d0, d1, d2, d3);
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2007-10-20 02:35:03 +08:00
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2007-07-21 23:10:42 +08:00
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get_debugreg(d6, 6);
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get_debugreg(d7, 7);
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2007-10-20 02:35:03 +08:00
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printk("DR6: %08lx DR7: %08lx\n",
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d6, d7);
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}
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2007-07-21 23:10:42 +08:00
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2007-10-20 02:35:03 +08:00
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void show_regs(struct pt_regs *regs)
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{
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2008-04-03 21:40:48 +08:00
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__show_regs(regs, 1);
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2008-01-30 20:33:07 +08:00
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show_trace(NULL, regs, ®s->sp, regs->bp);
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2005-04-17 06:20:36 +08:00
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}
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/*
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2008-01-30 20:30:56 +08:00
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* This gets run with %bx containing the
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* function to call, and %dx containing
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2005-04-17 06:20:36 +08:00
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* the "args".
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*/
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extern void kernel_thread_helper(void);
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/*
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* Create a kernel thread
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*/
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2009-01-04 18:48:56 +08:00
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int kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
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2005-04-17 06:20:36 +08:00
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{
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struct pt_regs regs;
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memset(®s, 0, sizeof(regs));
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2008-01-30 20:30:56 +08:00
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regs.bx = (unsigned long) fn;
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regs.dx = (unsigned long) arg;
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2005-04-17 06:20:36 +08:00
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2008-01-30 20:30:56 +08:00
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regs.ds = __USER_DS;
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regs.es = __USER_DS;
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regs.fs = __KERNEL_PERCPU;
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2009-02-09 21:17:40 +08:00
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regs.gs = __KERNEL_STACK_CANARY;
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2008-01-30 20:30:56 +08:00
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regs.orig_ax = -1;
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regs.ip = (unsigned long) kernel_thread_helper;
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regs.cs = __KERNEL_CS | get_kernel_rpl();
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regs.flags = X86_EFLAGS_IF | X86_EFLAGS_SF | X86_EFLAGS_PF | 0x2;
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2005-04-17 06:20:36 +08:00
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/* Ok, create the new process.. */
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2006-10-22 00:37:02 +08:00
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return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
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2005-04-17 06:20:36 +08:00
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}
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2005-06-23 15:08:33 +08:00
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EXPORT_SYMBOL(kernel_thread);
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2005-04-17 06:20:36 +08:00
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/*
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* Free current thread data structures etc..
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*/
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void exit_thread(void)
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{
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/* The process may have allocated an io port bitmap... nuke it. */
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2006-07-10 09:12:39 +08:00
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if (unlikely(test_thread_flag(TIF_IO_BITMAP))) {
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struct task_struct *tsk = current;
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struct thread_struct *t = &tsk->thread;
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2005-04-17 06:20:36 +08:00
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int cpu = get_cpu();
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struct tss_struct *tss = &per_cpu(init_tss, cpu);
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kfree(t->io_bitmap_ptr);
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t->io_bitmap_ptr = NULL;
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2006-07-10 09:12:39 +08:00
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clear_thread_flag(TIF_IO_BITMAP);
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2005-04-17 06:20:36 +08:00
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/*
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* Careful, clear this in the TSS too:
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*/
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memset(tss->io_bitmap, 0xff, tss->io_bitmap_max);
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t->io_bitmap_max = 0;
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tss->io_bitmap_owner = NULL;
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tss->io_bitmap_max = 0;
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2007-05-03 01:27:13 +08:00
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tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
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2005-04-17 06:20:36 +08:00
|
|
|
put_cpu();
|
|
|
|
}
|
2008-12-19 22:10:24 +08:00
|
|
|
|
|
|
|
ds_exit_thread(current);
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
void flush_thread(void)
|
|
|
|
{
|
|
|
|
struct task_struct *tsk = current;
|
|
|
|
|
2008-01-30 20:30:59 +08:00
|
|
|
tsk->thread.debugreg0 = 0;
|
|
|
|
tsk->thread.debugreg1 = 0;
|
|
|
|
tsk->thread.debugreg2 = 0;
|
|
|
|
tsk->thread.debugreg3 = 0;
|
|
|
|
tsk->thread.debugreg6 = 0;
|
|
|
|
tsk->thread.debugreg7 = 0;
|
2009-01-04 18:48:56 +08:00
|
|
|
memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
|
2006-07-10 09:12:39 +08:00
|
|
|
clear_tsk_thread_flag(tsk, TIF_DEBUG);
|
2005-04-17 06:20:36 +08:00
|
|
|
/*
|
|
|
|
* Forget coprocessor state..
|
|
|
|
*/
|
x86: fix NULL pointer deref in __switch_to
Patrick McHardy reported a crash:
> > I get this oops once a day, its apparently triggered by something
> > run by cron, but the process is a different one each time.
> >
> > Kernel is -git from yesterday shortly before the -rc6 release
> > (last commit is the usb-2.6 merge, the x86 patches are missing),
> > .config is attached.
> >
> > I'll retry with current -git, but the patches that have gone in
> > since I last updated don't look related.
> >
> > [62060.043009] BUG: unable to handle kernel NULL pointer dereference at
> > 000001ff
> > [62060.043009] IP: [<c0102a9b>] __switch_to+0x2f/0x118
> > [62060.043009] *pde = 00000000
> > [62060.043009] Oops: 0002 [#1] PREEMPT
Vegard Nossum analyzed it:
> This decodes to
>
> 0: 0f ae 00 fxsave (%eax)
>
> so it's related to the floating-point context. This is the exact
> location of the crash:
>
> $ addr2line -e arch/x86/kernel/process_32.o -i ab0
> include/asm/i387.h:232
> include/asm/i387.h:262
> arch/x86/kernel/process_32.c:595
>
> ...so it looks like prev_task->thread.xstate->fxsave has become NULL.
> Or maybe it never had any other value.
Somehow (as described below) TS_USEDFPU is set but the fpu is not
allocated or freed.
Another possible FPU pre-emption issue with the sleazy FPU optimization
which was benign before but not so anymore, with the dynamic FPU allocation
patch.
New task is getting exec'd and it is prempted at the below point.
flush_thread() {
...
/*
* Forget coprocessor state..
*/
clear_fpu(tsk);
<----- Preemption point
clear_used_math();
...
}
Now when it context switches in again, as the used_math() is still set
and fpu_counter can be > 5, we will do a math_state_restore() which sets
the task's TS_USEDFPU. After it continues from the above preemption point
it does clear_used_math() and much later free_thread_xstate().
Now, at the next context switch, it is quite possible that xstate is
null, used_math() is not set and TS_USEDFPU is still set. This will
trigger unlazy_fpu() causing kernel oops.
Fix this by clearing tsk's fpu_counter before clearing task's fpu.
Reported-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-14 06:47:12 +08:00
|
|
|
tsk->fpu_counter = 0;
|
2005-04-17 06:20:36 +08:00
|
|
|
clear_fpu(tsk);
|
|
|
|
clear_used_math();
|
|
|
|
}
|
|
|
|
|
|
|
|
void release_thread(struct task_struct *dead_task)
|
|
|
|
{
|
2006-01-06 16:11:59 +08:00
|
|
|
BUG_ON(dead_task->mm);
|
2005-04-17 06:20:36 +08:00
|
|
|
release_vm86_irqs(dead_task);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This gets called before we allocate a new thread and copy
|
|
|
|
* the current task into it.
|
|
|
|
*/
|
|
|
|
void prepare_to_copy(struct task_struct *tsk)
|
|
|
|
{
|
|
|
|
unlazy_fpu(tsk);
|
|
|
|
}
|
|
|
|
|
2008-01-30 20:30:56 +08:00
|
|
|
int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
|
2005-04-17 06:20:36 +08:00
|
|
|
unsigned long unused,
|
2009-01-04 18:48:56 +08:00
|
|
|
struct task_struct *p, struct pt_regs *regs)
|
2005-04-17 06:20:36 +08:00
|
|
|
{
|
2009-01-04 18:48:56 +08:00
|
|
|
struct pt_regs *childregs;
|
2005-04-17 06:20:36 +08:00
|
|
|
struct task_struct *tsk;
|
|
|
|
int err;
|
|
|
|
|
2006-01-12 17:05:41 +08:00
|
|
|
childregs = task_pt_regs(p);
|
2005-05-06 07:15:03 +08:00
|
|
|
*childregs = *regs;
|
2008-01-30 20:30:56 +08:00
|
|
|
childregs->ax = 0;
|
|
|
|
childregs->sp = sp;
|
2005-05-06 07:15:03 +08:00
|
|
|
|
2008-01-30 20:31:02 +08:00
|
|
|
p->thread.sp = (unsigned long) childregs;
|
|
|
|
p->thread.sp0 = (unsigned long) (childregs+1);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-01-30 20:31:02 +08:00
|
|
|
p->thread.ip = (unsigned long) ret_from_fork;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2009-02-09 21:17:40 +08:00
|
|
|
task_user_gs(p) = get_user_gs(regs);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
tsk = current;
|
2006-07-10 09:12:39 +08:00
|
|
|
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
|
2006-10-01 14:27:21 +08:00
|
|
|
p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
|
|
|
|
IO_BITMAP_BYTES, GFP_KERNEL);
|
2005-04-17 06:20:36 +08:00
|
|
|
if (!p->thread.io_bitmap_ptr) {
|
|
|
|
p->thread.io_bitmap_max = 0;
|
|
|
|
return -ENOMEM;
|
|
|
|
}
|
2006-07-10 09:12:39 +08:00
|
|
|
set_tsk_thread_flag(p, TIF_IO_BITMAP);
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
2008-01-30 20:30:46 +08:00
|
|
|
err = 0;
|
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
/*
|
|
|
|
* Set a new TLS for the child thread?
|
|
|
|
*/
|
2008-01-30 20:30:46 +08:00
|
|
|
if (clone_flags & CLONE_SETTLS)
|
|
|
|
err = do_set_thread_area(p, -1,
|
2008-01-30 20:30:56 +08:00
|
|
|
(struct user_desc __user *)childregs->si, 0);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
if (err && p->thread.io_bitmap_ptr) {
|
|
|
|
kfree(p->thread.io_bitmap_ptr);
|
|
|
|
p->thread.io_bitmap_max = 0;
|
|
|
|
}
|
2008-12-19 22:10:24 +08:00
|
|
|
|
|
|
|
ds_copy_thread(p, current);
|
|
|
|
|
|
|
|
clear_tsk_thread_flag(p, TIF_DEBUGCTLMSR);
|
|
|
|
p->thread.debugctlmsr = 0;
|
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
return err;
|
|
|
|
}
|
|
|
|
|
2008-02-21 12:18:40 +08:00
|
|
|
void
|
|
|
|
start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
|
|
|
|
{
|
2009-02-09 21:17:40 +08:00
|
|
|
set_user_gs(regs, 0);
|
2008-02-21 12:18:40 +08:00
|
|
|
regs->fs = 0;
|
|
|
|
set_fs(USER_DS);
|
|
|
|
regs->ds = __USER_DS;
|
|
|
|
regs->es = __USER_DS;
|
|
|
|
regs->ss = __USER_DS;
|
|
|
|
regs->cs = __USER_CS;
|
|
|
|
regs->ip = new_ip;
|
|
|
|
regs->sp = new_sp;
|
2008-03-11 06:28:05 +08:00
|
|
|
/*
|
|
|
|
* Free the old FP and other extended state
|
|
|
|
*/
|
|
|
|
free_thread_xstate(current);
|
2008-02-21 12:18:40 +08:00
|
|
|
}
|
|
|
|
EXPORT_SYMBOL_GPL(start_thread);
|
|
|
|
|
2008-01-30 20:31:21 +08:00
|
|
|
static void hard_disable_TSC(void)
|
2007-07-16 14:41:33 +08:00
|
|
|
{
|
|
|
|
write_cr4(read_cr4() | X86_CR4_TSD);
|
|
|
|
}
|
2008-04-14 06:24:18 +08:00
|
|
|
|
2007-07-16 14:41:33 +08:00
|
|
|
void disable_TSC(void)
|
|
|
|
{
|
|
|
|
preempt_disable();
|
|
|
|
if (!test_and_set_thread_flag(TIF_NOTSC))
|
|
|
|
/*
|
|
|
|
* Must flip the CPU state synchronously with
|
|
|
|
* TIF_NOTSC in the current running context.
|
|
|
|
*/
|
|
|
|
hard_disable_TSC();
|
|
|
|
preempt_enable();
|
|
|
|
}
|
2008-04-14 06:24:18 +08:00
|
|
|
|
2008-01-30 20:31:21 +08:00
|
|
|
static void hard_enable_TSC(void)
|
2007-07-16 14:41:33 +08:00
|
|
|
{
|
|
|
|
write_cr4(read_cr4() & ~X86_CR4_TSD);
|
|
|
|
}
|
2008-04-14 06:24:18 +08:00
|
|
|
|
2008-04-23 19:20:56 +08:00
|
|
|
static void enable_TSC(void)
|
2008-04-14 06:24:18 +08:00
|
|
|
{
|
|
|
|
preempt_disable();
|
|
|
|
if (test_and_clear_thread_flag(TIF_NOTSC))
|
|
|
|
/*
|
|
|
|
* Must flip the CPU state synchronously with
|
|
|
|
* TIF_NOTSC in the current running context.
|
|
|
|
*/
|
|
|
|
hard_enable_TSC();
|
|
|
|
preempt_enable();
|
|
|
|
}
|
|
|
|
|
|
|
|
int get_tsc_mode(unsigned long adr)
|
|
|
|
{
|
|
|
|
unsigned int val;
|
|
|
|
|
|
|
|
if (test_thread_flag(TIF_NOTSC))
|
|
|
|
val = PR_TSC_SIGSEGV;
|
|
|
|
else
|
|
|
|
val = PR_TSC_ENABLE;
|
|
|
|
|
|
|
|
return put_user(val, (unsigned int __user *)adr);
|
|
|
|
}
|
|
|
|
|
|
|
|
int set_tsc_mode(unsigned int val)
|
|
|
|
{
|
|
|
|
if (val == PR_TSC_SIGSEGV)
|
|
|
|
disable_TSC();
|
|
|
|
else if (val == PR_TSC_ENABLE)
|
|
|
|
enable_TSC();
|
|
|
|
else
|
|
|
|
return -EINVAL;
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
2007-07-16 14:41:33 +08:00
|
|
|
|
|
|
|
static noinline void
|
|
|
|
__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
|
|
|
|
struct tss_struct *tss)
|
2005-04-17 06:20:36 +08:00
|
|
|
{
|
2008-01-30 20:30:54 +08:00
|
|
|
struct thread_struct *prev, *next;
|
2006-07-10 09:12:39 +08:00
|
|
|
|
2008-01-30 20:30:54 +08:00
|
|
|
prev = &prev_p->thread;
|
2006-07-10 09:12:39 +08:00
|
|
|
next = &next_p->thread;
|
|
|
|
|
2008-12-11 20:49:59 +08:00
|
|
|
if (test_tsk_thread_flag(next_p, TIF_DS_AREA_MSR) ||
|
|
|
|
test_tsk_thread_flag(prev_p, TIF_DS_AREA_MSR))
|
|
|
|
ds_switch_to(prev_p, next_p);
|
|
|
|
else if (next->debugctlmsr != prev->debugctlmsr)
|
2008-03-10 21:11:17 +08:00
|
|
|
update_debugctlmsr(next->debugctlmsr);
|
2008-01-30 20:30:54 +08:00
|
|
|
|
2006-07-10 09:12:39 +08:00
|
|
|
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
|
2008-01-30 20:30:59 +08:00
|
|
|
set_debugreg(next->debugreg0, 0);
|
|
|
|
set_debugreg(next->debugreg1, 1);
|
|
|
|
set_debugreg(next->debugreg2, 2);
|
|
|
|
set_debugreg(next->debugreg3, 3);
|
2006-07-10 09:12:39 +08:00
|
|
|
/* no 4 and 5 */
|
2008-01-30 20:30:59 +08:00
|
|
|
set_debugreg(next->debugreg6, 6);
|
|
|
|
set_debugreg(next->debugreg7, 7);
|
2006-07-10 09:12:39 +08:00
|
|
|
}
|
|
|
|
|
2007-07-16 14:41:33 +08:00
|
|
|
if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
|
|
|
|
test_tsk_thread_flag(next_p, TIF_NOTSC)) {
|
|
|
|
/* prev and next are different */
|
|
|
|
if (test_tsk_thread_flag(next_p, TIF_NOTSC))
|
|
|
|
hard_disable_TSC();
|
|
|
|
else
|
|
|
|
hard_enable_TSC();
|
|
|
|
}
|
|
|
|
|
2006-07-10 09:12:39 +08:00
|
|
|
if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
|
2005-04-17 06:20:36 +08:00
|
|
|
/*
|
|
|
|
* Disable the bitmap via an invalid offset. We still cache
|
|
|
|
* the previous bitmap owner and the IO bitmap contents:
|
|
|
|
*/
|
2007-05-03 01:27:13 +08:00
|
|
|
tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
|
2005-04-17 06:20:36 +08:00
|
|
|
return;
|
|
|
|
}
|
2006-07-10 09:12:39 +08:00
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
if (likely(next == tss->io_bitmap_owner)) {
|
|
|
|
/*
|
|
|
|
* Previous owner of the bitmap (hence the bitmap content)
|
|
|
|
* matches the next task, we dont have to do anything but
|
|
|
|
* to set a valid offset in the TSS:
|
|
|
|
*/
|
2007-05-03 01:27:13 +08:00
|
|
|
tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
|
2005-04-17 06:20:36 +08:00
|
|
|
return;
|
|
|
|
}
|
|
|
|
/*
|
|
|
|
* Lazy TSS's I/O bitmap copy. We set an invalid offset here
|
|
|
|
* and we let the task to get a GPF in case an I/O instruction
|
|
|
|
* is performed. The handler of the GPF will verify that the
|
|
|
|
* faulting task has a valid I/O bitmap and, it true, does the
|
|
|
|
* real copy and restart the instruction. This will save us
|
|
|
|
* redundant copies when the currently switched task does not
|
|
|
|
* perform any I/O during its timeslice.
|
|
|
|
*/
|
2007-05-03 01:27:13 +08:00
|
|
|
tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* switch_to(x,yn) should switch tasks from x to y.
|
|
|
|
*
|
|
|
|
* We fsave/fwait so that an exception goes off at the right time
|
|
|
|
* (as a call from the fsave or fwait in effect) rather than to
|
|
|
|
* the wrong process. Lazy FP saving no longer makes any sense
|
|
|
|
* with modern CPU's, and this simplifies a lot of things (SMP
|
|
|
|
* and UP become the same).
|
|
|
|
*
|
|
|
|
* NOTE! We used to use the x86 hardware context switching. The
|
|
|
|
* reason for not using it any more becomes apparent when you
|
|
|
|
* try to recover gracefully from saved state that is no longer
|
|
|
|
* valid (stale segment register values in particular). With the
|
|
|
|
* hardware task-switch, there is no way to fix up bad state in
|
|
|
|
* a reasonable manner.
|
|
|
|
*
|
|
|
|
* The fact that Intel documents the hardware task-switching to
|
|
|
|
* be slow is a fairly red herring - this code is not noticeably
|
|
|
|
* faster. However, there _is_ some room for improvement here,
|
|
|
|
* so the performance issues may eventually be a valid point.
|
|
|
|
* More important, however, is the fact that this allows us much
|
|
|
|
* more flexibility.
|
|
|
|
*
|
2008-01-30 20:30:56 +08:00
|
|
|
* The return value (in %ax) will be the "prev" task after
|
2005-04-17 06:20:36 +08:00
|
|
|
* the task-switch, and shows up in ret_from_fork in entry.S,
|
|
|
|
* for example.
|
|
|
|
*/
|
2008-12-06 10:40:00 +08:00
|
|
|
__notrace_funcgraph struct task_struct *
|
|
|
|
__switch_to(struct task_struct *prev_p, struct task_struct *next_p)
|
2005-04-17 06:20:36 +08:00
|
|
|
{
|
|
|
|
struct thread_struct *prev = &prev_p->thread,
|
|
|
|
*next = &next_p->thread;
|
|
|
|
int cpu = smp_processor_id();
|
|
|
|
struct tss_struct *tss = &per_cpu(init_tss, cpu);
|
|
|
|
|
|
|
|
/* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
|
|
|
|
|
|
|
|
__unlazy_fpu(prev_p);
|
|
|
|
|
2006-12-07 09:14:01 +08:00
|
|
|
|
|
|
|
/* we're going to use this soon, after a few expensive things */
|
|
|
|
if (next_p->fpu_counter > 5)
|
2008-03-11 06:28:04 +08:00
|
|
|
prefetch(next->xstate);
|
2006-12-07 09:14:01 +08:00
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
/*
|
2005-09-04 06:56:39 +08:00
|
|
|
* Reload esp0.
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
2008-01-30 20:31:02 +08:00
|
|
|
load_sp0(tss, next);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
/*
|
2007-02-13 20:26:20 +08:00
|
|
|
* Save away %gs. No need to save %fs, as it was saved on the
|
[PATCH] i386: Use %gs as the PDA base-segment in the kernel
This patch is the meat of the PDA change. This patch makes several related
changes:
1: Most significantly, %gs is now used in the kernel. This means that on
entry, the old value of %gs is saved away, and it is reloaded with
__KERNEL_PDA.
2: entry.S constructs the stack in the shape of struct pt_regs, and this
is passed around the kernel so that the process's saved register
state can be accessed.
Unfortunately struct pt_regs doesn't currently have space for %gs
(or %fs). This patch extends pt_regs to add space for gs (no space
is allocated for %fs, since it won't be used, and it would just
complicate the code in entry.S to work around the space).
3: Because %gs is now saved on the stack like %ds, %es and the integer
registers, there are a number of places where it no longer needs to
be handled specially; namely context switch, and saving/restoring the
register state in a signal context.
4: And since kernel threads run in kernel space and call normal kernel
code, they need to be created with their %gs == __KERNEL_PDA.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
2006-12-07 09:14:02 +08:00
|
|
|
* stack on entry. No need to save %es and %ds, as those are
|
|
|
|
* always kernel segments while inside the kernel. Doing this
|
|
|
|
* before setting the new TLS descriptors avoids the situation
|
|
|
|
* where we temporarily have non-reloadable segments in %fs
|
|
|
|
* and %gs. This could be an issue if the NMI handler ever
|
|
|
|
* used %fs or %gs (it does not today), or if the kernel is
|
|
|
|
* running inside of a hypervisor layer.
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
2009-02-09 21:17:40 +08:00
|
|
|
lazy_save_gs(prev->gs);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
/*
|
2005-09-04 06:56:39 +08:00
|
|
|
* Load the per-thread Thread-Local Storage descriptor.
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
2005-09-04 06:56:39 +08:00
|
|
|
load_TLS(next, cpu);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2007-02-13 20:26:21 +08:00
|
|
|
/*
|
|
|
|
* Restore IOPL if needed. In normal use, the flags restore
|
|
|
|
* in the switch assembly will handle this. But if the kernel
|
|
|
|
* is running virtualized at a non-zero CPL, the popf will
|
|
|
|
* not restore flags, so it must be done in a separate step.
|
|
|
|
*/
|
|
|
|
if (get_kernel_rpl() && unlikely(prev->iopl != next->iopl))
|
|
|
|
set_iopl_mask(next->iopl);
|
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
/*
|
2006-07-10 09:12:39 +08:00
|
|
|
* Now maybe handle debug registers and/or IO bitmaps
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
2007-07-16 14:41:33 +08:00
|
|
|
if (unlikely(task_thread_info(prev_p)->flags & _TIF_WORK_CTXSW_PREV ||
|
|
|
|
task_thread_info(next_p)->flags & _TIF_WORK_CTXSW_NEXT))
|
|
|
|
__switch_to_xtra(prev_p, next_p, tss);
|
2005-06-28 05:36:36 +08:00
|
|
|
|
2007-02-13 20:26:21 +08:00
|
|
|
/*
|
|
|
|
* Leave lazy mode, flushing any hypercalls made here.
|
|
|
|
* This must be done before restoring TLS segments so
|
|
|
|
* the GDT and LDT are properly updated, and must be
|
|
|
|
* done before math_state_restore, so the TS bit is up
|
|
|
|
* to date.
|
|
|
|
*/
|
|
|
|
arch_leave_lazy_cpu_mode();
|
|
|
|
|
2006-12-07 09:14:01 +08:00
|
|
|
/* If the task has used fpu the last 5 timeslices, just do a full
|
|
|
|
* restore of the math state immediately to avoid the trap; the
|
|
|
|
* chances of needing FPU soon are obviously high now
|
2008-06-03 06:57:27 +08:00
|
|
|
*
|
|
|
|
* tsk_used_math() checks prevent calling math_state_restore(),
|
|
|
|
* which can sleep in the case of !tsk_used_math()
|
2006-12-07 09:14:01 +08:00
|
|
|
*/
|
2008-06-03 06:57:27 +08:00
|
|
|
if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
|
2006-12-07 09:14:01 +08:00
|
|
|
math_state_restore();
|
|
|
|
|
2007-02-13 20:26:21 +08:00
|
|
|
/*
|
|
|
|
* Restore %gs if needed (which is common)
|
|
|
|
*/
|
|
|
|
if (prev->gs | next->gs)
|
2009-02-09 21:17:40 +08:00
|
|
|
lazy_load_gs(next->gs);
|
2007-02-13 20:26:21 +08:00
|
|
|
|
percpu: add optimized generic percpu accessors
It is an optimization and a cleanup, and adds the following new
generic percpu methods:
percpu_read()
percpu_write()
percpu_add()
percpu_sub()
percpu_and()
percpu_or()
percpu_xor()
and implements support for them on x86. (other architectures will fall
back to a default implementation)
The advantage is that for example to read a local percpu variable,
instead of this sequence:
return __get_cpu_var(var);
ffffffff8102ca2b: 48 8b 14 fd 80 09 74 mov -0x7e8bf680(,%rdi,8),%rdx
ffffffff8102ca32: 81
ffffffff8102ca33: 48 c7 c0 d8 59 00 00 mov $0x59d8,%rax
ffffffff8102ca3a: 48 8b 04 10 mov (%rax,%rdx,1),%rax
We can get a single instruction by using the optimized variants:
return percpu_read(var);
ffffffff8102ca3f: 65 48 8b 05 91 8f fd mov %gs:0x7efd8f91(%rip),%rax
I also cleaned up the x86-specific APIs and made the x86 code use
these new generic percpu primitives.
tj: * fixed generic percpu_sub() definition as Roel Kluin pointed out
* added percpu_and() for completeness's sake
* made generic percpu ops atomic against preemption
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Tejun Heo <tj@kernel.org>
2009-01-15 21:15:53 +08:00
|
|
|
percpu_write(current_task, next_p);
|
2007-02-13 20:26:21 +08:00
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
return prev_p;
|
|
|
|
}
|
|
|
|
|
|
|
|
asmlinkage int sys_fork(struct pt_regs regs)
|
|
|
|
{
|
2008-01-30 20:30:56 +08:00
|
|
|
return do_fork(SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
asmlinkage int sys_clone(struct pt_regs regs)
|
|
|
|
{
|
|
|
|
unsigned long clone_flags;
|
|
|
|
unsigned long newsp;
|
|
|
|
int __user *parent_tidptr, *child_tidptr;
|
|
|
|
|
2008-01-30 20:30:56 +08:00
|
|
|
clone_flags = regs.bx;
|
|
|
|
newsp = regs.cx;
|
|
|
|
parent_tidptr = (int __user *)regs.dx;
|
|
|
|
child_tidptr = (int __user *)regs.di;
|
2005-04-17 06:20:36 +08:00
|
|
|
if (!newsp)
|
2008-01-30 20:30:56 +08:00
|
|
|
newsp = regs.sp;
|
2005-04-17 06:20:36 +08:00
|
|
|
return do_fork(clone_flags, newsp, ®s, 0, parent_tidptr, child_tidptr);
|
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* This is trivial, and on the face of it looks like it
|
|
|
|
* could equally well be done in user mode.
|
|
|
|
*
|
|
|
|
* Not so, for quite unobvious reasons - register pressure.
|
|
|
|
* In user mode vfork() cannot have a stack frame, and if
|
|
|
|
* done by calling the "clone()" system call directly, you
|
|
|
|
* do not have enough call-clobbered registers to hold all
|
|
|
|
* the information you need.
|
|
|
|
*/
|
|
|
|
asmlinkage int sys_vfork(struct pt_regs regs)
|
|
|
|
{
|
2008-01-30 20:30:56 +08:00
|
|
|
return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
/*
|
|
|
|
* sys_execve() executes a new program.
|
|
|
|
*/
|
|
|
|
asmlinkage int sys_execve(struct pt_regs regs)
|
|
|
|
{
|
|
|
|
int error;
|
2009-01-04 18:48:56 +08:00
|
|
|
char *filename;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-01-30 20:30:56 +08:00
|
|
|
filename = getname((char __user *) regs.bx);
|
2005-04-17 06:20:36 +08:00
|
|
|
error = PTR_ERR(filename);
|
|
|
|
if (IS_ERR(filename))
|
|
|
|
goto out;
|
|
|
|
error = do_execve(filename,
|
2008-01-30 20:30:56 +08:00
|
|
|
(char __user * __user *) regs.cx,
|
|
|
|
(char __user * __user *) regs.dx,
|
2005-04-17 06:20:36 +08:00
|
|
|
®s);
|
|
|
|
if (error == 0) {
|
|
|
|
/* Make sure we don't return using sysenter.. */
|
|
|
|
set_thread_flag(TIF_IRET);
|
|
|
|
}
|
|
|
|
putname(filename);
|
|
|
|
out:
|
|
|
|
return error;
|
|
|
|
}
|
|
|
|
|
|
|
|
#define top_esp (THREAD_SIZE - sizeof(unsigned long))
|
|
|
|
#define top_ebp (THREAD_SIZE - 2*sizeof(unsigned long))
|
|
|
|
|
|
|
|
unsigned long get_wchan(struct task_struct *p)
|
|
|
|
{
|
2008-01-30 20:30:56 +08:00
|
|
|
unsigned long bp, sp, ip;
|
2005-04-17 06:20:36 +08:00
|
|
|
unsigned long stack_page;
|
|
|
|
int count = 0;
|
|
|
|
if (!p || p == current || p->state == TASK_RUNNING)
|
|
|
|
return 0;
|
2006-01-12 17:05:41 +08:00
|
|
|
stack_page = (unsigned long)task_stack_page(p);
|
2008-01-30 20:31:02 +08:00
|
|
|
sp = p->thread.sp;
|
2008-01-30 20:30:56 +08:00
|
|
|
if (!stack_page || sp < stack_page || sp > top_esp+stack_page)
|
2005-04-17 06:20:36 +08:00
|
|
|
return 0;
|
2008-01-30 20:30:56 +08:00
|
|
|
/* include/asm-i386/system.h:switch_to() pushes bp last. */
|
|
|
|
bp = *(unsigned long *) sp;
|
2005-04-17 06:20:36 +08:00
|
|
|
do {
|
2008-01-30 20:30:56 +08:00
|
|
|
if (bp < stack_page || bp > top_ebp+stack_page)
|
2005-04-17 06:20:36 +08:00
|
|
|
return 0;
|
2008-01-30 20:30:56 +08:00
|
|
|
ip = *(unsigned long *) (bp+4);
|
|
|
|
if (!in_sched_functions(ip))
|
|
|
|
return ip;
|
|
|
|
bp = *(unsigned long *) bp;
|
2005-04-17 06:20:36 +08:00
|
|
|
} while (count++ < 16);
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
unsigned long arch_align_stack(unsigned long sp)
|
|
|
|
{
|
2006-09-26 16:52:28 +08:00
|
|
|
if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
|
2005-04-17 06:20:36 +08:00
|
|
|
sp -= get_random_int() % 8192;
|
|
|
|
return sp & ~0xf;
|
|
|
|
}
|
2008-01-30 20:30:40 +08:00
|
|
|
|
|
|
|
unsigned long arch_randomize_brk(struct mm_struct *mm)
|
|
|
|
{
|
|
|
|
unsigned long range_end = mm->brk + 0x02000000;
|
|
|
|
return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
|
|
|
|
}
|