![Linus Torvalds](/assets/img/avatar_default.png)
Pull fpu state cleanups from Ingo Molnar: "This tree streamlines further aspects of FPU handling by eliminating the prepare_to_copy() complication and moving that logic to arch_dup_task_struct(). It also fixes the FPU dumps in threaded core dumps, removes and old (and now invalid) assumption plus micro-optimizes the exit path by avoiding an FPU save for dead tasks." Fixed up trivial add-add conflict in arch/sh/kernel/process.c that came in because we now do the FPU handling in arch_dup_task_struct() rather than the legacy (and now gone) prepare_to_copy(). * 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, fpu: drop the fpu state during thread exit x86, xsave: remove thread_has_fpu() bug check in __sanitize_i387_state() coredump: ensure the fpu state is flushed for proper multi-threaded core dump fork: move the real prepare_to_copy() users to arch_dup_task_struct()
762 lines
18 KiB
C
762 lines
18 KiB
C
#include <linux/errno.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/prctl.h>
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#include <linux/slab.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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#include <linux/pm.h>
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#include <linux/clockchips.h>
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#include <linux/random.h>
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#include <linux/user-return-notifier.h>
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#include <linux/dmi.h>
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#include <linux/utsname.h>
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#include <linux/stackprotector.h>
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#include <linux/tick.h>
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#include <linux/cpuidle.h>
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#include <trace/events/power.h>
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#include <linux/hw_breakpoint.h>
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#include <asm/cpu.h>
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#include <asm/apic.h>
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#include <asm/syscalls.h>
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#include <asm/idle.h>
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#include <asm/uaccess.h>
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#include <asm/i387.h>
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#include <asm/fpu-internal.h>
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#include <asm/debugreg.h>
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#include <asm/nmi.h>
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/*
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* per-CPU TSS segments. Threads are completely 'soft' on Linux,
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* no more per-task TSS's. The TSS size is kept cacheline-aligned
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* so they are allowed to end up in the .data..cacheline_aligned
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* section. Since TSS's are completely CPU-local, we want them
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* on exact cacheline boundaries, to eliminate cacheline ping-pong.
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*/
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DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, init_tss) = INIT_TSS;
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#ifdef CONFIG_X86_64
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static DEFINE_PER_CPU(unsigned char, is_idle);
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static ATOMIC_NOTIFIER_HEAD(idle_notifier);
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void idle_notifier_register(struct notifier_block *n)
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{
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atomic_notifier_chain_register(&idle_notifier, n);
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}
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EXPORT_SYMBOL_GPL(idle_notifier_register);
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void idle_notifier_unregister(struct notifier_block *n)
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{
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atomic_notifier_chain_unregister(&idle_notifier, n);
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}
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EXPORT_SYMBOL_GPL(idle_notifier_unregister);
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#endif
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struct kmem_cache *task_xstate_cachep;
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EXPORT_SYMBOL_GPL(task_xstate_cachep);
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/*
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* this gets called so that we can store lazy state into memory and copy the
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* current task into the new thread.
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*/
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int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
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{
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int ret;
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unlazy_fpu(src);
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*dst = *src;
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if (fpu_allocated(&src->thread.fpu)) {
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memset(&dst->thread.fpu, 0, sizeof(dst->thread.fpu));
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ret = fpu_alloc(&dst->thread.fpu);
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if (ret)
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return ret;
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fpu_copy(&dst->thread.fpu, &src->thread.fpu);
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}
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return 0;
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}
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void free_thread_xstate(struct task_struct *tsk)
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{
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fpu_free(&tsk->thread.fpu);
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}
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void arch_release_task_struct(struct task_struct *tsk)
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{
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free_thread_xstate(tsk);
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}
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void arch_task_cache_init(void)
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{
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task_xstate_cachep =
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kmem_cache_create("task_xstate", xstate_size,
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__alignof__(union thread_xstate),
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SLAB_PANIC | SLAB_NOTRACK, NULL);
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}
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static inline void drop_fpu(struct task_struct *tsk)
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{
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/*
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* Forget coprocessor state..
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*/
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tsk->fpu_counter = 0;
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clear_fpu(tsk);
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clear_used_math();
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}
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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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struct task_struct *me = current;
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struct thread_struct *t = &me->thread;
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unsigned long *bp = t->io_bitmap_ptr;
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if (bp) {
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struct tss_struct *tss = &per_cpu(init_tss, get_cpu());
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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, t->io_bitmap_max);
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t->io_bitmap_max = 0;
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put_cpu();
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kfree(bp);
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}
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drop_fpu(me);
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}
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void show_regs_common(void)
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{
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const char *vendor, *product, *board;
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vendor = dmi_get_system_info(DMI_SYS_VENDOR);
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if (!vendor)
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vendor = "";
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product = dmi_get_system_info(DMI_PRODUCT_NAME);
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if (!product)
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product = "";
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/* Board Name is optional */
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board = dmi_get_system_info(DMI_BOARD_NAME);
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printk(KERN_CONT "\n");
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printk(KERN_DEFAULT "Pid: %d, comm: %.20s %s %s %.*s",
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current->pid, current->comm, print_tainted(),
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init_utsname()->release,
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(int)strcspn(init_utsname()->version, " "),
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init_utsname()->version);
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printk(KERN_CONT " %s %s", vendor, product);
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if (board)
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printk(KERN_CONT "/%s", board);
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printk(KERN_CONT "\n");
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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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flush_ptrace_hw_breakpoint(tsk);
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memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));
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drop_fpu(tsk);
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}
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static void hard_disable_TSC(void)
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{
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write_cr4(read_cr4() | X86_CR4_TSD);
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}
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void disable_TSC(void)
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{
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preempt_disable();
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if (!test_and_set_thread_flag(TIF_NOTSC))
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/*
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* Must flip the CPU state synchronously with
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* TIF_NOTSC in the current running context.
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*/
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hard_disable_TSC();
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preempt_enable();
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}
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static void hard_enable_TSC(void)
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{
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write_cr4(read_cr4() & ~X86_CR4_TSD);
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}
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static void enable_TSC(void)
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{
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preempt_disable();
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if (test_and_clear_thread_flag(TIF_NOTSC))
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/*
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* Must flip the CPU state synchronously with
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* TIF_NOTSC in the current running context.
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*/
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hard_enable_TSC();
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preempt_enable();
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}
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int get_tsc_mode(unsigned long adr)
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{
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unsigned int val;
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if (test_thread_flag(TIF_NOTSC))
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val = PR_TSC_SIGSEGV;
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else
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val = PR_TSC_ENABLE;
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return put_user(val, (unsigned int __user *)adr);
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}
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int set_tsc_mode(unsigned int val)
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{
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if (val == PR_TSC_SIGSEGV)
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disable_TSC();
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else if (val == PR_TSC_ENABLE)
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enable_TSC();
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else
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return -EINVAL;
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return 0;
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}
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void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
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struct tss_struct *tss)
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{
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struct thread_struct *prev, *next;
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prev = &prev_p->thread;
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next = &next_p->thread;
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if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
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test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
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unsigned long debugctl = get_debugctlmsr();
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debugctl &= ~DEBUGCTLMSR_BTF;
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if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
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debugctl |= DEBUGCTLMSR_BTF;
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update_debugctlmsr(debugctl);
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}
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if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
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test_tsk_thread_flag(next_p, TIF_NOTSC)) {
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/* prev and next are different */
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if (test_tsk_thread_flag(next_p, TIF_NOTSC))
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hard_disable_TSC();
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else
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hard_enable_TSC();
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}
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if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
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/*
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* Copy the relevant range of the IO bitmap.
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* Normally this is 128 bytes or less:
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*/
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memcpy(tss->io_bitmap, next->io_bitmap_ptr,
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max(prev->io_bitmap_max, next->io_bitmap_max));
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} else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
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/*
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* Clear any possible leftover bits:
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*/
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memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
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}
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propagate_user_return_notify(prev_p, next_p);
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}
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int sys_fork(struct pt_regs *regs)
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{
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return do_fork(SIGCHLD, regs->sp, regs, 0, NULL, NULL);
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}
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/*
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* This is trivial, and on the face of it looks like it
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* could equally well be done in user mode.
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*
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* Not so, for quite unobvious reasons - register pressure.
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* In user mode vfork() cannot have a stack frame, and if
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* done by calling the "clone()" system call directly, you
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* do not have enough call-clobbered registers to hold all
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* the information you need.
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*/
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int sys_vfork(struct pt_regs *regs)
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{
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return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, regs->sp, regs, 0,
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NULL, NULL);
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}
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long
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sys_clone(unsigned long clone_flags, unsigned long newsp,
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void __user *parent_tid, void __user *child_tid, struct pt_regs *regs)
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{
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if (!newsp)
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newsp = regs->sp;
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return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
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}
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/*
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* This gets run with %si containing the
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* function to call, and %di 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.si = (unsigned long) fn;
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regs.di = (unsigned long) arg;
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#ifdef CONFIG_X86_32
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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.gs = __KERNEL_STACK_CANARY;
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#else
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regs.ss = __KERNEL_DS;
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#endif
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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_BIT1;
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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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* sys_execve() executes a new program.
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*/
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long sys_execve(const char __user *name,
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const char __user *const __user *argv,
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const char __user *const __user *envp, struct pt_regs *regs)
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{
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long error;
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char *filename;
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filename = getname(name);
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error = PTR_ERR(filename);
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if (IS_ERR(filename))
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return error;
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error = do_execve(filename, argv, envp, regs);
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#ifdef CONFIG_X86_32
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if (error == 0) {
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/* Make sure we don't return using sysenter.. */
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set_thread_flag(TIF_IRET);
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}
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#endif
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putname(filename);
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return error;
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}
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/*
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* Idle related variables and functions
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*/
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unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
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EXPORT_SYMBOL(boot_option_idle_override);
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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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#ifdef CONFIG_APM_MODULE
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EXPORT_SYMBOL(pm_idle);
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#endif
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static inline int hlt_use_halt(void)
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{
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return 1;
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}
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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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#ifdef CONFIG_X86_64
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void enter_idle(void)
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{
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this_cpu_write(is_idle, 1);
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atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
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}
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static void __exit_idle(void)
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{
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if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
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return;
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atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
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}
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/* Called from interrupts to signify idle end */
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void exit_idle(void)
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{
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/* idle loop has pid 0 */
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if (current->pid)
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return;
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__exit_idle();
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}
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#endif
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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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/*
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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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current_thread_info()->status |= TS_POLLING;
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while (1) {
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tick_nohz_idle_enter();
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while (!need_resched()) {
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rmb();
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if (cpu_is_offline(smp_processor_id()))
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play_dead();
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/*
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* Idle routines should keep interrupts disabled
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* from here on, until they go to idle.
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* Otherwise, idle callbacks can misfire.
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*/
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local_touch_nmi();
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local_irq_disable();
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enter_idle();
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/* Don't trace irqs off for idle */
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stop_critical_timings();
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/* enter_idle() needs rcu for notifiers */
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rcu_idle_enter();
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if (cpuidle_idle_call())
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pm_idle();
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rcu_idle_exit();
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start_critical_timings();
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/* In many cases the interrupt that ended idle
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has already called exit_idle. But some idle
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loops can be woken up without interrupt. */
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__exit_idle();
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}
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tick_nohz_idle_exit();
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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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/*
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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_use_halt()) {
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trace_power_start_rcuidle(POWER_CSTATE, 1, smp_processor_id());
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trace_cpu_idle_rcuidle(1, smp_processor_id());
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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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if (!need_resched())
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safe_halt(); /* enables interrupts racelessly */
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else
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local_irq_enable();
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current_thread_info()->status |= TS_POLLING;
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trace_power_end_rcuidle(smp_processor_id());
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trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
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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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bool set_pm_idle_to_default(void)
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{
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bool ret = !!pm_idle;
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pm_idle = default_idle;
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return ret;
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}
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void stop_this_cpu(void *dummy)
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{
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local_irq_disable();
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/*
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* Remove this CPU:
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*/
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set_cpu_online(smp_processor_id(), false);
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disable_local_APIC();
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for (;;) {
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if (hlt_works(smp_processor_id()))
|
|
halt();
|
|
}
|
|
}
|
|
|
|
/* Default MONITOR/MWAIT with no hints, used for default C1 state */
|
|
static void mwait_idle(void)
|
|
{
|
|
if (!need_resched()) {
|
|
trace_power_start_rcuidle(POWER_CSTATE, 1, smp_processor_id());
|
|
trace_cpu_idle_rcuidle(1, smp_processor_id());
|
|
if (this_cpu_has(X86_FEATURE_CLFLUSH_MONITOR))
|
|
clflush((void *)¤t_thread_info()->flags);
|
|
|
|
__monitor((void *)¤t_thread_info()->flags, 0, 0);
|
|
smp_mb();
|
|
if (!need_resched())
|
|
__sti_mwait(0, 0);
|
|
else
|
|
local_irq_enable();
|
|
trace_power_end_rcuidle(smp_processor_id());
|
|
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
|
|
} else
|
|
local_irq_enable();
|
|
}
|
|
|
|
/*
|
|
* On SMP it's slightly faster (but much more power-consuming!)
|
|
* to poll the ->work.need_resched flag instead of waiting for the
|
|
* cross-CPU IPI to arrive. Use this option with caution.
|
|
*/
|
|
static void poll_idle(void)
|
|
{
|
|
trace_power_start_rcuidle(POWER_CSTATE, 0, smp_processor_id());
|
|
trace_cpu_idle_rcuidle(0, smp_processor_id());
|
|
local_irq_enable();
|
|
while (!need_resched())
|
|
cpu_relax();
|
|
trace_power_end_rcuidle(smp_processor_id());
|
|
trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
|
|
}
|
|
|
|
/*
|
|
* mwait selection logic:
|
|
*
|
|
* It depends on the CPU. For AMD CPUs that support MWAIT this is
|
|
* wrong. Family 0x10 and 0x11 CPUs will enter C1 on HLT. Powersavings
|
|
* then depend on a clock divisor and current Pstate of the core. If
|
|
* all cores of a processor are in halt state (C1) the processor can
|
|
* enter the C1E (C1 enhanced) state. If mwait is used this will never
|
|
* happen.
|
|
*
|
|
* idle=mwait overrides this decision and forces the usage of mwait.
|
|
*/
|
|
|
|
#define MWAIT_INFO 0x05
|
|
#define MWAIT_ECX_EXTENDED_INFO 0x01
|
|
#define MWAIT_EDX_C1 0xf0
|
|
|
|
int mwait_usable(const struct cpuinfo_x86 *c)
|
|
{
|
|
u32 eax, ebx, ecx, edx;
|
|
|
|
/* Use mwait if idle=mwait boot option is given */
|
|
if (boot_option_idle_override == IDLE_FORCE_MWAIT)
|
|
return 1;
|
|
|
|
/*
|
|
* Any idle= boot option other than idle=mwait means that we must not
|
|
* use mwait. Eg: idle=halt or idle=poll or idle=nomwait
|
|
*/
|
|
if (boot_option_idle_override != IDLE_NO_OVERRIDE)
|
|
return 0;
|
|
|
|
if (c->cpuid_level < MWAIT_INFO)
|
|
return 0;
|
|
|
|
cpuid(MWAIT_INFO, &eax, &ebx, &ecx, &edx);
|
|
/* Check, whether EDX has extended info about MWAIT */
|
|
if (!(ecx & MWAIT_ECX_EXTENDED_INFO))
|
|
return 1;
|
|
|
|
/*
|
|
* edx enumeratios MONITOR/MWAIT extensions. Check, whether
|
|
* C1 supports MWAIT
|
|
*/
|
|
return (edx & MWAIT_EDX_C1);
|
|
}
|
|
|
|
bool amd_e400_c1e_detected;
|
|
EXPORT_SYMBOL(amd_e400_c1e_detected);
|
|
|
|
static cpumask_var_t amd_e400_c1e_mask;
|
|
|
|
void amd_e400_remove_cpu(int cpu)
|
|
{
|
|
if (amd_e400_c1e_mask != NULL)
|
|
cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
|
|
}
|
|
|
|
/*
|
|
* AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
|
|
* pending message MSR. If we detect C1E, then we handle it the same
|
|
* way as C3 power states (local apic timer and TSC stop)
|
|
*/
|
|
static void amd_e400_idle(void)
|
|
{
|
|
if (need_resched())
|
|
return;
|
|
|
|
if (!amd_e400_c1e_detected) {
|
|
u32 lo, hi;
|
|
|
|
rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
|
|
|
|
if (lo & K8_INTP_C1E_ACTIVE_MASK) {
|
|
amd_e400_c1e_detected = true;
|
|
if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
|
|
mark_tsc_unstable("TSC halt in AMD C1E");
|
|
printk(KERN_INFO "System has AMD C1E enabled\n");
|
|
}
|
|
}
|
|
|
|
if (amd_e400_c1e_detected) {
|
|
int cpu = smp_processor_id();
|
|
|
|
if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
|
|
cpumask_set_cpu(cpu, amd_e400_c1e_mask);
|
|
/*
|
|
* Force broadcast so ACPI can not interfere.
|
|
*/
|
|
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
|
|
&cpu);
|
|
printk(KERN_INFO "Switch to broadcast mode on CPU%d\n",
|
|
cpu);
|
|
}
|
|
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
|
|
|
|
default_idle();
|
|
|
|
/*
|
|
* The switch back from broadcast mode needs to be
|
|
* called with interrupts disabled.
|
|
*/
|
|
local_irq_disable();
|
|
clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
|
|
local_irq_enable();
|
|
} else
|
|
default_idle();
|
|
}
|
|
|
|
void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c)
|
|
{
|
|
#ifdef CONFIG_SMP
|
|
if (pm_idle == poll_idle && smp_num_siblings > 1) {
|
|
printk_once(KERN_WARNING "WARNING: polling idle and HT enabled,"
|
|
" performance may degrade.\n");
|
|
}
|
|
#endif
|
|
if (pm_idle)
|
|
return;
|
|
|
|
if (cpu_has(c, X86_FEATURE_MWAIT) && mwait_usable(c)) {
|
|
/*
|
|
* One CPU supports mwait => All CPUs supports mwait
|
|
*/
|
|
printk(KERN_INFO "using mwait in idle threads.\n");
|
|
pm_idle = mwait_idle;
|
|
} else if (cpu_has_amd_erratum(amd_erratum_400)) {
|
|
/* E400: APIC timer interrupt does not wake up CPU from C1e */
|
|
printk(KERN_INFO "using AMD E400 aware idle routine\n");
|
|
pm_idle = amd_e400_idle;
|
|
} else
|
|
pm_idle = default_idle;
|
|
}
|
|
|
|
void __init init_amd_e400_c1e_mask(void)
|
|
{
|
|
/* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
|
|
if (pm_idle == amd_e400_idle)
|
|
zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
|
|
}
|
|
|
|
static int __init idle_setup(char *str)
|
|
{
|
|
if (!str)
|
|
return -EINVAL;
|
|
|
|
if (!strcmp(str, "poll")) {
|
|
printk("using polling idle threads.\n");
|
|
pm_idle = poll_idle;
|
|
boot_option_idle_override = IDLE_POLL;
|
|
} else if (!strcmp(str, "mwait")) {
|
|
boot_option_idle_override = IDLE_FORCE_MWAIT;
|
|
WARN_ONCE(1, "\"idle=mwait\" will be removed in 2012\n");
|
|
} else if (!strcmp(str, "halt")) {
|
|
/*
|
|
* When the boot option of idle=halt is added, halt is
|
|
* forced to be used for CPU idle. In such case CPU C2/C3
|
|
* won't be used again.
|
|
* To continue to load the CPU idle driver, don't touch
|
|
* the boot_option_idle_override.
|
|
*/
|
|
pm_idle = default_idle;
|
|
boot_option_idle_override = IDLE_HALT;
|
|
} else if (!strcmp(str, "nomwait")) {
|
|
/*
|
|
* If the boot option of "idle=nomwait" is added,
|
|
* it means that mwait will be disabled for CPU C2/C3
|
|
* states. In such case it won't touch the variable
|
|
* of boot_option_idle_override.
|
|
*/
|
|
boot_option_idle_override = IDLE_NOMWAIT;
|
|
} else
|
|
return -1;
|
|
|
|
return 0;
|
|
}
|
|
early_param("idle", idle_setup);
|
|
|
|
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;
|
|
}
|
|
|