![Linus Torvalds](/assets/img/avatar_default.png)
Pull x86 asm updates from Ingo Molnar: "This is another big update. Main changes are: - lots of x86 system call (and other traps/exceptions) entry code enhancements. In particular the complex parts of the 64-bit entry code have been migrated to C code as well, and a number of dusty corners have been refreshed. (Andy Lutomirski) - vDSO special mapping robustification and general cleanups (Andy Lutomirski) - cpufeature refactoring, cleanups and speedups (Borislav Petkov) - lots of other changes ..." * 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (64 commits) x86/cpufeature: Enable new AVX-512 features x86/entry/traps: Show unhandled signal for i386 in do_trap() x86/entry: Call enter_from_user_mode() with IRQs off x86/entry/32: Change INT80 to be an interrupt gate x86/entry: Improve system call entry comments x86/entry: Remove TIF_SINGLESTEP entry work x86/entry/32: Add and check a stack canary for the SYSENTER stack x86/entry/32: Simplify and fix up the SYSENTER stack #DB/NMI fixup x86/entry: Only allocate space for tss_struct::SYSENTER_stack if needed x86/entry: Vastly simplify SYSENTER TF (single-step) handling x86/entry/traps: Clear DR6 early in do_debug() and improve the comment x86/entry/traps: Clear TIF_BLOCKSTEP on all debug exceptions x86/entry/32: Restore FLAGS on SYSEXIT x86/entry/32: Filter NT and speed up AC filtering in SYSENTER x86/entry/compat: In SYSENTER, sink AC clearing below the existing FLAGS test selftests/x86: In syscall_nt, test NT|TF as well x86/asm-offsets: Remove PARAVIRT_enabled x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled uprobes: __create_xol_area() must nullify xol_mapping.fault x86/cpufeature: Create a new synthetic cpu capability for machine check recovery ...
570 lines
13 KiB
C
570 lines
13 KiB
C
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#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/tick.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/mwait.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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#include <asm/tlbflush.h>
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#include <asm/mce.h>
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#include <asm/vm86.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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__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
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.x86_tss = {
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.sp0 = TOP_OF_INIT_STACK,
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#ifdef CONFIG_X86_32
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.ss0 = __KERNEL_DS,
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.ss1 = __KERNEL_CS,
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.io_bitmap_base = INVALID_IO_BITMAP_OFFSET,
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#endif
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},
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#ifdef CONFIG_X86_32
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/*
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* Note that the .io_bitmap member must be extra-big. This is because
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* the CPU will access an additional byte beyond the end of the IO
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* permission bitmap. The extra byte must be all 1 bits, and must
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* be within the limit.
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*/
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.io_bitmap = { [0 ... IO_BITMAP_LONGS] = ~0 },
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#endif
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#ifdef CONFIG_X86_32
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.SYSENTER_stack_canary = STACK_END_MAGIC,
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#endif
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};
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EXPORT_PER_CPU_SYMBOL(cpu_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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/*
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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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memcpy(dst, src, arch_task_struct_size);
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#ifdef CONFIG_VM86
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dst->thread.vm86 = NULL;
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#endif
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return fpu__copy(&dst->thread.fpu, &src->thread.fpu);
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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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struct fpu *fpu = &t->fpu;
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if (bp) {
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struct tss_struct *tss = &per_cpu(cpu_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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free_vm86(t);
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fpu__drop(fpu);
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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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fpu__clear(&tsk->thread.fpu);
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}
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static void hard_disable_TSC(void)
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{
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cr4_set_bits(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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cr4_clear_bits(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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/*
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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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static void (*x86_idle)(void);
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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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void arch_cpu_idle_enter(void)
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{
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local_touch_nmi();
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enter_idle();
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}
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void arch_cpu_idle_exit(void)
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{
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__exit_idle();
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}
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void arch_cpu_idle_dead(void)
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{
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play_dead();
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}
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/*
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* Called from the generic idle code.
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*/
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void arch_cpu_idle(void)
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{
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x86_idle();
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}
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/*
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* We use this if we don't have any better idle routine..
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*/
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void default_idle(void)
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{
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trace_cpu_idle_rcuidle(1, smp_processor_id());
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safe_halt();
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trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
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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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#ifdef CONFIG_XEN
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bool xen_set_default_idle(void)
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{
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bool ret = !!x86_idle;
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x86_idle = default_idle;
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return ret;
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}
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#endif
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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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mcheck_cpu_clear(this_cpu_ptr(&cpu_info));
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for (;;)
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halt();
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}
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bool amd_e400_c1e_detected;
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EXPORT_SYMBOL(amd_e400_c1e_detected);
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static cpumask_var_t amd_e400_c1e_mask;
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void amd_e400_remove_cpu(int cpu)
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{
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if (amd_e400_c1e_mask != NULL)
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cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
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}
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/*
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* AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
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* pending message MSR. If we detect C1E, then we handle it the same
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* way as C3 power states (local apic timer and TSC stop)
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*/
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static void amd_e400_idle(void)
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{
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if (!amd_e400_c1e_detected) {
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u32 lo, hi;
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rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);
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if (lo & K8_INTP_C1E_ACTIVE_MASK) {
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amd_e400_c1e_detected = true;
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if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
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mark_tsc_unstable("TSC halt in AMD C1E");
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pr_info("System has AMD C1E enabled\n");
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}
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}
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if (amd_e400_c1e_detected) {
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int cpu = smp_processor_id();
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if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
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cpumask_set_cpu(cpu, amd_e400_c1e_mask);
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/* Force broadcast so ACPI can not interfere. */
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tick_broadcast_force();
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pr_info("Switch to broadcast mode on CPU%d\n", cpu);
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}
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tick_broadcast_enter();
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default_idle();
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/*
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* The switch back from broadcast mode needs to be
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* called with interrupts disabled.
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*/
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local_irq_disable();
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tick_broadcast_exit();
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local_irq_enable();
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} else
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default_idle();
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}
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/*
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* Intel Core2 and older machines prefer MWAIT over HALT for C1.
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* We can't rely on cpuidle installing MWAIT, because it will not load
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* on systems that support only C1 -- so the boot default must be MWAIT.
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*
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* Some AMD machines are the opposite, they depend on using HALT.
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*
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* So for default C1, which is used during boot until cpuidle loads,
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* use MWAIT-C1 on Intel HW that has it, else use HALT.
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*/
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static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
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{
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if (c->x86_vendor != X86_VENDOR_INTEL)
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return 0;
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if (!cpu_has(c, X86_FEATURE_MWAIT))
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return 0;
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return 1;
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}
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/*
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* MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT
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* with interrupts enabled and no flags, which is backwards compatible with the
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* original MWAIT implementation.
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*/
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static void mwait_idle(void)
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{
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if (!current_set_polling_and_test()) {
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trace_cpu_idle_rcuidle(1, smp_processor_id());
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if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
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mb(); /* quirk */
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clflush((void *)¤t_thread_info()->flags);
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mb(); /* quirk */
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}
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__monitor((void *)¤t_thread_info()->flags, 0, 0);
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if (!need_resched())
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__sti_mwait(0, 0);
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else
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local_irq_enable();
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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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}
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__current_clr_polling();
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}
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void select_idle_routine(const struct cpuinfo_x86 *c)
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{
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#ifdef CONFIG_SMP
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if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
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pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
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#endif
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if (x86_idle || boot_option_idle_override == IDLE_POLL)
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return;
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if (cpu_has_bug(c, X86_BUG_AMD_APIC_C1E)) {
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/* E400: APIC timer interrupt does not wake up CPU from C1e */
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pr_info("using AMD E400 aware idle routine\n");
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x86_idle = amd_e400_idle;
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} else if (prefer_mwait_c1_over_halt(c)) {
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pr_info("using mwait in idle threads\n");
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x86_idle = mwait_idle;
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} else
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x86_idle = default_idle;
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}
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void __init init_amd_e400_c1e_mask(void)
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{
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/* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
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if (x86_idle == amd_e400_idle)
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zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
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}
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static int __init idle_setup(char *str)
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{
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if (!str)
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return -EINVAL;
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if (!strcmp(str, "poll")) {
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pr_info("using polling idle threads\n");
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boot_option_idle_override = IDLE_POLL;
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cpu_idle_poll_ctrl(true);
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} else if (!strcmp(str, "halt")) {
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/*
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* When the boot option of idle=halt is added, halt is
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* forced to be used for CPU idle. In such case CPU C2/C3
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* won't be used again.
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* To continue to load the CPU idle driver, don't touch
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* the boot_option_idle_override.
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*/
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x86_idle = default_idle;
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boot_option_idle_override = IDLE_HALT;
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} else if (!strcmp(str, "nomwait")) {
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/*
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* 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;
|
|
}
|
|
|
|
/*
|
|
* Called from fs/proc with a reference on @p to find the function
|
|
* which called into schedule(). This needs to be done carefully
|
|
* because the task might wake up and we might look at a stack
|
|
* changing under us.
|
|
*/
|
|
unsigned long get_wchan(struct task_struct *p)
|
|
{
|
|
unsigned long start, bottom, top, sp, fp, ip;
|
|
int count = 0;
|
|
|
|
if (!p || p == current || p->state == TASK_RUNNING)
|
|
return 0;
|
|
|
|
start = (unsigned long)task_stack_page(p);
|
|
if (!start)
|
|
return 0;
|
|
|
|
/*
|
|
* Layout of the stack page:
|
|
*
|
|
* ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)
|
|
* PADDING
|
|
* ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
|
|
* stack
|
|
* ----------- bottom = start + sizeof(thread_info)
|
|
* thread_info
|
|
* ----------- start
|
|
*
|
|
* The tasks stack pointer points at the location where the
|
|
* framepointer is stored. The data on the stack is:
|
|
* ... IP FP ... IP FP
|
|
*
|
|
* We need to read FP and IP, so we need to adjust the upper
|
|
* bound by another unsigned long.
|
|
*/
|
|
top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;
|
|
top -= 2 * sizeof(unsigned long);
|
|
bottom = start + sizeof(struct thread_info);
|
|
|
|
sp = READ_ONCE(p->thread.sp);
|
|
if (sp < bottom || sp > top)
|
|
return 0;
|
|
|
|
fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
|
|
do {
|
|
if (fp < bottom || fp > top)
|
|
return 0;
|
|
ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
|
|
if (!in_sched_functions(ip))
|
|
return ip;
|
|
fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
|
|
} while (count++ < 16 && p->state != TASK_RUNNING);
|
|
return 0;
|
|
}
|