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(addr: 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(irq: 0, handler: timer_interrupt, flags, name: "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

source code of linux/arch/x86/kernel/time.c