529e25f646
This patch implements the PR_GET_TSC and PR_SET_TSC prctl() commands on the x86 platform (both 32 and 64 bit.) These commands control the ability to read the timestamp counter from userspace (the RDTSC instruction.) While the RDTSC instuction is a useful profiling tool, it is also the source of some non-determinism in ring-3. For deterministic replay applications it is useful to be able to trap and emulate (and record the outcome of) this instruction. This patch uses code earlier used to disable the timestamp counter for the SECCOMP framework. A side-effect of this patch is that the SECCOMP environment will now also disable the timestamp counter on x86_64 due to the addition of the TIF_NOTSC define on this platform. The code which enables/disables the RDTSC instruction during context switches is in the __switch_to_xtra function, which already handles other unusual conditions, so normal performance should not have to suffer from this change. Signed-off-by: Erik Bosman <ejbosman@cs.vu.nl> Acked-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
872 lines
21 KiB
C
872 lines
21 KiB
C
/*
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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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#include <linux/cpu.h>
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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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#include <linux/personality.h>
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#include <linux/tick.h>
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#include <linux/percpu.h>
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#include <linux/prctl.h>
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#include <asm/uaccess.h>
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#include <asm/pgtable.h>
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#include <asm/system.h>
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#include <asm/io.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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#include <asm/tlbflush.h>
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#include <asm/cpu.h>
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#include <asm/kdebug.h>
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asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
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static int hlt_counter;
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unsigned long boot_option_idle_override = 0;
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EXPORT_SYMBOL(boot_option_idle_override);
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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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DEFINE_PER_CPU(int, cpu_number);
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EXPORT_PER_CPU_SYMBOL(cpu_number);
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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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return ((unsigned long *)tsk->thread.sp)[3];
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}
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/*
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* Powermanagement idle function, if any..
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*/
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void (*pm_idle)(void);
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EXPORT_SYMBOL(pm_idle);
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void disable_hlt(void)
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{
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hlt_counter++;
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}
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EXPORT_SYMBOL(disable_hlt);
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void enable_hlt(void)
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{
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hlt_counter--;
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}
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EXPORT_SYMBOL(enable_hlt);
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/*
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* We use this if we don't have any better
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* idle routine..
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*/
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void default_idle(void)
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{
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if (!hlt_counter && boot_cpu_data.hlt_works_ok) {
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current_thread_info()->status &= ~TS_POLLING;
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/*
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* TS_POLLING-cleared state must be visible before we
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* test NEED_RESCHED:
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*/
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smp_mb();
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local_irq_disable();
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if (!need_resched()) {
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safe_halt(); /* enables interrupts racelessly */
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local_irq_disable();
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}
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local_irq_enable();
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current_thread_info()->status |= TS_POLLING;
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} else {
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local_irq_enable();
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/* loop is done by the caller */
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cpu_relax();
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}
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}
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#ifdef CONFIG_APM_MODULE
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EXPORT_SYMBOL(default_idle);
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#endif
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/*
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* On SMP it's slightly faster (but much more power-consuming!)
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* to poll the ->work.need_resched flag instead of waiting for the
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* cross-CPU IPI to arrive. Use this option with caution.
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*/
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static void poll_idle(void)
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{
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local_irq_enable();
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cpu_relax();
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}
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#ifdef CONFIG_HOTPLUG_CPU
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#include <asm/nmi.h>
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/* We don't actually take CPU down, just spin without interrupts. */
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static inline void play_dead(void)
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{
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/* This must be done before dead CPU ack */
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cpu_exit_clear();
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wbinvd();
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mb();
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/* Ack it */
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__get_cpu_var(cpu_state) = CPU_DEAD;
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/*
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* With physical CPU hotplug, we should halt the cpu
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*/
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local_irq_disable();
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while (1)
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halt();
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}
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#else
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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 /* CONFIG_HOTPLUG_CPU */
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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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void cpu_idle(void)
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{
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int cpu = smp_processor_id();
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current_thread_info()->status |= TS_POLLING;
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/* endless idle loop with no priority at all */
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while (1) {
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tick_nohz_stop_sched_tick();
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while (!need_resched()) {
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void (*idle)(void);
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check_pgt_cache();
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rmb();
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idle = pm_idle;
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if (rcu_pending(cpu))
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rcu_check_callbacks(cpu, 0);
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if (!idle)
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idle = default_idle;
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if (cpu_is_offline(cpu))
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play_dead();
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__get_cpu_var(irq_stat).idle_timestamp = jiffies;
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idle();
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}
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tick_nohz_restart_sched_tick();
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preempt_enable_no_resched();
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schedule();
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preempt_disable();
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}
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}
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static void do_nothing(void *unused)
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{
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}
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/*
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* cpu_idle_wait - Used to ensure that all the CPUs discard old value of
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* pm_idle and update to new pm_idle value. Required while changing pm_idle
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* handler on SMP systems.
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*
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* Caller must have changed pm_idle to the new value before the call. Old
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* pm_idle value will not be used by any CPU after the return of this function.
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*/
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void cpu_idle_wait(void)
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{
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smp_mb();
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/* kick all the CPUs so that they exit out of pm_idle */
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smp_call_function(do_nothing, NULL, 0, 1);
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}
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EXPORT_SYMBOL_GPL(cpu_idle_wait);
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/*
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* This uses new MONITOR/MWAIT instructions on P4 processors with PNI,
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* which can obviate IPI to trigger checking of need_resched.
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* We execute MONITOR against need_resched and enter optimized wait state
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* through MWAIT. Whenever someone changes need_resched, we would be woken
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* up from MWAIT (without an IPI).
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*
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* New with Core Duo processors, MWAIT can take some hints based on CPU
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* capability.
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*/
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void mwait_idle_with_hints(unsigned long ax, unsigned long cx)
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{
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if (!need_resched()) {
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__monitor((void *)¤t_thread_info()->flags, 0, 0);
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smp_mb();
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if (!need_resched())
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__sti_mwait(ax, cx);
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else
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local_irq_enable();
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} else
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local_irq_enable();
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}
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/* Default MONITOR/MWAIT with no hints, used for default C1 state */
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static void mwait_idle(void)
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{
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local_irq_enable();
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mwait_idle_with_hints(0, 0);
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}
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static int __cpuinit mwait_usable(const struct cpuinfo_x86 *c)
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{
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if (force_mwait)
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return 1;
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/* Any C1 states supported? */
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return c->cpuid_level >= 5 && ((cpuid_edx(5) >> 4) & 0xf) > 0;
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}
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void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
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{
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static int selected;
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if (selected)
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return;
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#ifdef CONFIG_X86_SMP
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if (pm_idle == poll_idle && smp_num_siblings > 1) {
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printk(KERN_WARNING "WARNING: polling idle and HT enabled,"
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" performance may degrade.\n");
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}
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#endif
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if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
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/*
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* Skip, if setup has overridden idle.
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* One CPU supports mwait => All CPUs supports mwait
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*/
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if (!pm_idle) {
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printk(KERN_INFO "using mwait in idle threads.\n");
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pm_idle = mwait_idle;
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}
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}
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selected = 1;
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}
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static int __init idle_setup(char *str)
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{
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if (!strcmp(str, "poll")) {
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printk("using polling idle threads.\n");
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pm_idle = poll_idle;
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} else if (!strcmp(str, "mwait"))
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force_mwait = 1;
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else
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return -1;
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boot_option_idle_override = 1;
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return 0;
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}
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early_param("idle", idle_setup);
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void __show_registers(struct pt_regs *regs, int all)
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{
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unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
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unsigned long d0, d1, d2, d3, d6, d7;
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unsigned long sp;
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unsigned short ss, gs;
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if (user_mode_vm(regs)) {
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sp = regs->sp;
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ss = regs->ss & 0xffff;
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savesegment(gs, gs);
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} else {
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sp = (unsigned long) (®s->sp);
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savesegment(ss, ss);
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savesegment(gs, gs);
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}
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printk("\n");
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printk("Pid: %d, comm: %s %s (%s %.*s)\n",
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task_pid_nr(current), current->comm,
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print_tainted(), init_utsname()->release,
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(int)strcspn(init_utsname()->version, " "),
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init_utsname()->version);
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printk("EIP: %04x:[<%08lx>] EFLAGS: %08lx CPU: %d\n",
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(u16)regs->cs, regs->ip, regs->flags,
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smp_processor_id());
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print_symbol("EIP is at %s\n", regs->ip);
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printk("EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n",
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regs->ax, regs->bx, regs->cx, regs->dx);
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printk("ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n",
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regs->si, regs->di, regs->bp, sp);
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printk(" DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x\n",
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(u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, ss);
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if (!all)
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return;
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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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cr4 = read_cr4_safe();
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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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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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get_debugreg(d6, 6);
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get_debugreg(d7, 7);
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printk("DR6: %08lx DR7: %08lx\n",
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d6, d7);
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}
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void show_regs(struct pt_regs *regs)
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{
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__show_registers(regs, 1);
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show_trace(NULL, regs, ®s->sp, regs->bp);
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}
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/*
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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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* 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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int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
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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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regs.bx = (unsigned long) fn;
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regs.dx = (unsigned long) arg;
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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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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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/* Ok, create the new process.. */
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return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, ®s, 0, NULL, NULL);
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}
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EXPORT_SYMBOL(kernel_thread);
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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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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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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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clear_thread_flag(TIF_IO_BITMAP);
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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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tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
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put_cpu();
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}
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}
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void flush_thread(void)
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{
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struct task_struct *tsk = current;
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tsk->thread.debugreg0 = 0;
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tsk->thread.debugreg1 = 0;
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tsk->thread.debugreg2 = 0;
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tsk->thread.debugreg3 = 0;
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tsk->thread.debugreg6 = 0;
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tsk->thread.debugreg7 = 0;
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memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
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clear_tsk_thread_flag(tsk, TIF_DEBUG);
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/*
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* Forget coprocessor state..
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*/
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clear_fpu(tsk);
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clear_used_math();
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}
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void release_thread(struct task_struct *dead_task)
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{
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BUG_ON(dead_task->mm);
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release_vm86_irqs(dead_task);
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}
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/*
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* This gets called before we allocate a new thread and copy
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* the current task into it.
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*/
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void prepare_to_copy(struct task_struct *tsk)
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{
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unlazy_fpu(tsk);
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}
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int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
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unsigned long unused,
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struct task_struct * p, struct pt_regs * regs)
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{
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struct pt_regs * childregs;
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struct task_struct *tsk;
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int err;
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childregs = task_pt_regs(p);
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*childregs = *regs;
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childregs->ax = 0;
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childregs->sp = sp;
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p->thread.sp = (unsigned long) childregs;
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p->thread.sp0 = (unsigned long) (childregs+1);
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p->thread.ip = (unsigned long) ret_from_fork;
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savesegment(gs, p->thread.gs);
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tsk = current;
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if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
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p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
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IO_BITMAP_BYTES, GFP_KERNEL);
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if (!p->thread.io_bitmap_ptr) {
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p->thread.io_bitmap_max = 0;
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return -ENOMEM;
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}
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set_tsk_thread_flag(p, TIF_IO_BITMAP);
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}
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err = 0;
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/*
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* Set a new TLS for the child thread?
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*/
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if (clone_flags & CLONE_SETTLS)
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err = do_set_thread_area(p, -1,
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(struct user_desc __user *)childregs->si, 0);
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if (err && p->thread.io_bitmap_ptr) {
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kfree(p->thread.io_bitmap_ptr);
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p->thread.io_bitmap_max = 0;
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}
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return err;
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}
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void
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start_thread(struct pt_regs *regs, unsigned long new_ip, unsigned long new_sp)
|
|
{
|
|
__asm__("movl %0, %%gs" :: "r"(0));
|
|
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;
|
|
}
|
|
EXPORT_SYMBOL_GPL(start_thread);
|
|
|
|
static void hard_disable_TSC(void)
|
|
{
|
|
write_cr4(read_cr4() | X86_CR4_TSD);
|
|
}
|
|
|
|
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();
|
|
}
|
|
|
|
static void hard_enable_TSC(void)
|
|
{
|
|
write_cr4(read_cr4() & ~X86_CR4_TSD);
|
|
}
|
|
|
|
void enable_TSC(void)
|
|
{
|
|
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;
|
|
}
|
|
|
|
static noinline void
|
|
__switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
|
|
struct tss_struct *tss)
|
|
{
|
|
struct thread_struct *prev, *next;
|
|
unsigned long debugctl;
|
|
|
|
prev = &prev_p->thread;
|
|
next = &next_p->thread;
|
|
|
|
debugctl = prev->debugctlmsr;
|
|
if (next->ds_area_msr != prev->ds_area_msr) {
|
|
/* we clear debugctl to make sure DS
|
|
* is not in use when we change it */
|
|
debugctl = 0;
|
|
update_debugctlmsr(0);
|
|
wrmsr(MSR_IA32_DS_AREA, next->ds_area_msr, 0);
|
|
}
|
|
|
|
if (next->debugctlmsr != debugctl)
|
|
update_debugctlmsr(next->debugctlmsr);
|
|
|
|
if (test_tsk_thread_flag(next_p, TIF_DEBUG)) {
|
|
set_debugreg(next->debugreg0, 0);
|
|
set_debugreg(next->debugreg1, 1);
|
|
set_debugreg(next->debugreg2, 2);
|
|
set_debugreg(next->debugreg3, 3);
|
|
/* no 4 and 5 */
|
|
set_debugreg(next->debugreg6, 6);
|
|
set_debugreg(next->debugreg7, 7);
|
|
}
|
|
|
|
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();
|
|
}
|
|
|
|
#ifdef X86_BTS
|
|
if (test_tsk_thread_flag(prev_p, TIF_BTS_TRACE_TS))
|
|
ptrace_bts_take_timestamp(prev_p, BTS_TASK_DEPARTS);
|
|
|
|
if (test_tsk_thread_flag(next_p, TIF_BTS_TRACE_TS))
|
|
ptrace_bts_take_timestamp(next_p, BTS_TASK_ARRIVES);
|
|
#endif
|
|
|
|
|
|
if (!test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
|
|
/*
|
|
* Disable the bitmap via an invalid offset. We still cache
|
|
* the previous bitmap owner and the IO bitmap contents:
|
|
*/
|
|
tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET;
|
|
return;
|
|
}
|
|
|
|
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:
|
|
*/
|
|
tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET;
|
|
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.
|
|
*/
|
|
tss->x86_tss.io_bitmap_base = INVALID_IO_BITMAP_OFFSET_LAZY;
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* The return value (in %ax) will be the "prev" task after
|
|
* the task-switch, and shows up in ret_from_fork in entry.S,
|
|
* for example.
|
|
*/
|
|
struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
|
|
{
|
|
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);
|
|
|
|
|
|
/* we're going to use this soon, after a few expensive things */
|
|
if (next_p->fpu_counter > 5)
|
|
prefetch(&next->i387.fxsave);
|
|
|
|
/*
|
|
* Reload esp0.
|
|
*/
|
|
load_sp0(tss, next);
|
|
|
|
/*
|
|
* Save away %gs. No need to save %fs, as it was saved on the
|
|
* 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.
|
|
*/
|
|
savesegment(gs, prev->gs);
|
|
|
|
/*
|
|
* Load the per-thread Thread-Local Storage descriptor.
|
|
*/
|
|
load_TLS(next, cpu);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
/*
|
|
* Now maybe handle debug registers and/or IO bitmaps
|
|
*/
|
|
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);
|
|
|
|
/*
|
|
* 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();
|
|
|
|
/* 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
|
|
*/
|
|
if (next_p->fpu_counter > 5)
|
|
math_state_restore();
|
|
|
|
/*
|
|
* Restore %gs if needed (which is common)
|
|
*/
|
|
if (prev->gs | next->gs)
|
|
loadsegment(gs, next->gs);
|
|
|
|
x86_write_percpu(current_task, next_p);
|
|
|
|
return prev_p;
|
|
}
|
|
|
|
asmlinkage int sys_fork(struct pt_regs regs)
|
|
{
|
|
return do_fork(SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
|
|
}
|
|
|
|
asmlinkage int sys_clone(struct pt_regs regs)
|
|
{
|
|
unsigned long clone_flags;
|
|
unsigned long newsp;
|
|
int __user *parent_tidptr, *child_tidptr;
|
|
|
|
clone_flags = regs.bx;
|
|
newsp = regs.cx;
|
|
parent_tidptr = (int __user *)regs.dx;
|
|
child_tidptr = (int __user *)regs.di;
|
|
if (!newsp)
|
|
newsp = regs.sp;
|
|
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)
|
|
{
|
|
return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs.sp, ®s, 0, NULL, NULL);
|
|
}
|
|
|
|
/*
|
|
* sys_execve() executes a new program.
|
|
*/
|
|
asmlinkage int sys_execve(struct pt_regs regs)
|
|
{
|
|
int error;
|
|
char * filename;
|
|
|
|
filename = getname((char __user *) regs.bx);
|
|
error = PTR_ERR(filename);
|
|
if (IS_ERR(filename))
|
|
goto out;
|
|
error = do_execve(filename,
|
|
(char __user * __user *) regs.cx,
|
|
(char __user * __user *) regs.dx,
|
|
®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)
|
|
{
|
|
unsigned long bp, sp, ip;
|
|
unsigned long stack_page;
|
|
int count = 0;
|
|
if (!p || p == current || p->state == TASK_RUNNING)
|
|
return 0;
|
|
stack_page = (unsigned long)task_stack_page(p);
|
|
sp = p->thread.sp;
|
|
if (!stack_page || sp < stack_page || sp > top_esp+stack_page)
|
|
return 0;
|
|
/* include/asm-i386/system.h:switch_to() pushes bp last. */
|
|
bp = *(unsigned long *) sp;
|
|
do {
|
|
if (bp < stack_page || bp > top_ebp+stack_page)
|
|
return 0;
|
|
ip = *(unsigned long *) (bp+4);
|
|
if (!in_sched_functions(ip))
|
|
return ip;
|
|
bp = *(unsigned long *) bp;
|
|
} while (count++ < 16);
|
|
return 0;
|
|
}
|
|
|
|
unsigned long arch_align_stack(unsigned long sp)
|
|
{
|
|
if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
|
|
sp -= get_random_int() % 8192;
|
|
return sp & ~0xf;
|
|
}
|
|
|
|
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;
|
|
}
|