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TPAUSE instructs the processor to enter an implementation-dependent optimized state. The instruction execution wakes up when the time-stamp counter reaches or exceeds the implicit EDX:EAX 64-bit input value. The instruction execution also wakes up due to the expiration of the operating system time-limit or by an external interrupt or exceptions such as a debug exception or a machine check exception. TPAUSE offers a choice of two lower power states: 1. Light-weight power/performance optimized state C0.1 2. Improved power/performance optimized state C0.2 This way, it can save power with low wake-up latency in comparison to spinloop based delay. The selection between the two is governed by the input register. TPAUSE is available on processors with X86_FEATURE_WAITPKG. Co-developed-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Signed-off-by: Kyung Min Park <kyung.min.park@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Link: https://lkml.kernel.org/r/1587757076-30337-4-git-send-email-kyung.min.park@intel.com
133 lines
3.1 KiB
C
133 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 1991,1992,1995 Linus Torvalds
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* Copyright (c) 1994 Alan Modra
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* Copyright (c) 1995 Markus Kuhn
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* Copyright (c) 1996 Ingo Molnar
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* Copyright (c) 1998 Andrea Arcangeli
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* Copyright (c) 2002,2006 Vojtech Pavlik
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* Copyright (c) 2003 Andi Kleen
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*
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*/
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/i8253.h>
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#include <linux/time.h>
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#include <linux/export.h>
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#include <asm/vsyscall.h>
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#include <asm/x86_init.h>
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#include <asm/i8259.h>
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#include <asm/timer.h>
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#include <asm/hpet.h>
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#include <asm/time.h>
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#ifdef CONFIG_X86_64
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__visible volatile unsigned long jiffies __cacheline_aligned_in_smp = INITIAL_JIFFIES;
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#endif
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unsigned long profile_pc(struct pt_regs *regs)
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{
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unsigned long pc = instruction_pointer(regs);
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if (!user_mode(regs) && in_lock_functions(pc)) {
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#ifdef CONFIG_FRAME_POINTER
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return *(unsigned long *)(regs->bp + sizeof(long));
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#else
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unsigned long *sp = (unsigned long *)regs->sp;
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/*
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* Return address is either directly at stack pointer
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* or above a saved flags. Eflags has bits 22-31 zero,
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* kernel addresses don't.
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*/
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if (sp[0] >> 22)
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return sp[0];
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if (sp[1] >> 22)
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return sp[1];
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#endif
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}
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return pc;
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}
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EXPORT_SYMBOL(profile_pc);
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/*
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* Default timer interrupt handler for PIT/HPET
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*/
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static irqreturn_t timer_interrupt(int irq, void *dev_id)
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{
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global_clock_event->event_handler(global_clock_event);
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return IRQ_HANDLED;
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}
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static void __init setup_default_timer_irq(void)
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{
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unsigned long flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER;
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/*
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* Unconditionally register the legacy timer interrupt; even
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* without legacy PIC/PIT we need this for the HPET0 in legacy
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* replacement mode.
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*/
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if (request_irq(0, timer_interrupt, flags, "timer", NULL))
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pr_info("Failed to register legacy timer interrupt\n");
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}
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/* Default timer init function */
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void __init hpet_time_init(void)
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{
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if (!hpet_enable()) {
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if (!pit_timer_init())
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return;
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}
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setup_default_timer_irq();
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}
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static __init void x86_late_time_init(void)
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{
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/*
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* Before PIT/HPET init, select the interrupt mode. This is required
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* to make the decision whether PIT should be initialized correct.
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*/
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x86_init.irqs.intr_mode_select();
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/* Setup the legacy timers */
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x86_init.timers.timer_init();
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/*
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* After PIT/HPET timers init, set up the final interrupt mode for
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* delivering IRQs.
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*/
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x86_init.irqs.intr_mode_init();
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tsc_init();
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if (static_cpu_has(X86_FEATURE_WAITPKG))
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use_tpause_delay();
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}
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/*
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* Initialize TSC and delay the periodic timer init to
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* late x86_late_time_init() so ioremap works.
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*/
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void __init time_init(void)
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{
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late_time_init = x86_late_time_init;
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}
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/*
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* Sanity check the vdso related archdata content.
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*/
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void clocksource_arch_init(struct clocksource *cs)
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{
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if (cs->vdso_clock_mode == VDSO_CLOCKMODE_NONE)
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return;
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if (cs->mask != CLOCKSOURCE_MASK(64)) {
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pr_warn("clocksource %s registered with invalid mask %016llx for VDSO. Disabling VDSO support.\n",
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cs->name, cs->mask);
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cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE;
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}
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}
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