LXR linux/arch/x86/kernel/time.c

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  Copyright (c) 1991,1992,1995  Linus Torvalds
   4 *  Copyright (c) 1994  Alan Modra
   5 *  Copyright (c) 1995  Markus Kuhn
   6 *  Copyright (c) 1996  Ingo Molnar
   7 *  Copyright (c) 1998  Andrea Arcangeli
   8 *  Copyright (c) 2002,2006  Vojtech Pavlik
   9 *  Copyright (c) 2003  Andi Kleen
  10 *
  11 */
  12
  13#include <linux/clocksource.h>
  14#include <linux/clockchips.h>
  15#include <linux/interrupt.h>
  16#include <linux/irq.h>
  17#include <linux/i8253.h>
  18#include <linux/time.h>
  19#include <linux/export.h>
  20
  21#include <asm/vsyscall.h>
  22#include <asm/x86_init.h>
  23#include <asm/i8259.h>
  24#include <asm/timer.h>
  25#include <asm/hpet.h>
  26#include <asm/time.h>
  27
  28unsigned long profile_pc(struct pt_regs *regs)
  29{
  30        unsigned long pc = instruction_pointer(regs);
  31
  32        if (!user_mode(regs) && in_lock_functions(pc)) {
  33#ifdef CONFIG_FRAME_POINTER
  34                return *(unsigned long *)(regs->bp + sizeof(long));
  35#else
  36                unsigned long *sp = (unsigned long *)regs->sp;
  37                /*
  38                 * Return address is either directly at stack pointer
  39                 * or above a saved flags. Eflags has bits 22-31 zero,
  40                 * kernel addresses don't.
  41                 */
  42                if (sp[0] >> 22)
  43                        return sp[0];
  44                if (sp[1] >> 22)
  45                        return sp[1];
  46#endif
  47        }
  48        return pc;
  49}
  50EXPORT_SYMBOL(profile_pc);
  51
  52/*
  53 * Default timer interrupt handler for PIT/HPET
  54 */
  55static irqreturn_t timer_interrupt(int irq, void *dev_id)
  56{
  57        global_clock_event->event_handler(global_clock_event);
  58        return IRQ_HANDLED;
  59}
  60
  61static void __init setup_default_timer_irq(void)
  62{
  63        unsigned long flags = IRQF_NOBALANCING | IRQF_IRQPOLL | IRQF_TIMER;
  64
  65        /*
  66         * Unconditionally register the legacy timer interrupt; even
  67         * without legacy PIC/PIT we need this for the HPET0 in legacy
  68         * replacement mode.
  69         */
  70        if (request_irq(0, timer_interrupt, flags, "timer", NULL))
  71                pr_info("Failed to register legacy timer interrupt\n");
  72}
  73
  74/* Default timer init function */
  75void __init hpet_time_init(void)
  76{
  77        if (!hpet_enable()) {
  78                if (!pit_timer_init())
  79                        return;
  80        }
  81
  82        setup_default_timer_irq();
  83}
  84
  85static __init void x86_late_time_init(void)
  86{
  87        /*
  88         * Before PIT/HPET init, select the interrupt mode. This is required
  89         * to make the decision whether PIT should be initialized correct.
  90         */
  91        x86_init.irqs.intr_mode_select();
  92
  93        /* Setup the legacy timers */
  94        x86_init.timers.timer_init();
  95
  96        /*
  97         * After PIT/HPET timers init, set up the final interrupt mode for
  98         * delivering IRQs.
  99         */
 100        x86_init.irqs.intr_mode_init();
 101        tsc_init();
 102
 103        if (static_cpu_has(X86_FEATURE_WAITPKG))
 104                use_tpause_delay();
 105}
 106
 107/*
 108 * Initialize TSC and delay the periodic timer init to
 109 * late x86_late_time_init() so ioremap works.
 110 */
 111void __init time_init(void)
 112{
 113        late_time_init = x86_late_time_init;
 114}
 115
 116/*
 117 * Sanity check the vdso related archdata content.
 118 */
 119void clocksource_arch_init(struct clocksource *cs)
 120{
 121        if (cs->vdso_clock_mode == VDSO_CLOCKMODE_NONE)
 122                return;
 123
 124        if (cs->mask != CLOCKSOURCE_MASK(64)) {
 125                pr_warn("clocksource %s registered with invalid mask %016llx for VDSO. Disabling VDSO support.\n",
 126                        cs->name, cs->mask);
 127                cs->vdso_clock_mode = VDSO_CLOCKMODE_NONE;
 128        }
 129}
 130