swh:1:snp:32555a3fd8878f019c2ebd6c964bc1edcaeff337
Tip revision: 7d2a07b769330c34b4deabeed939325c77a7ec2f authored by Linus Torvalds on 29 August 2021, 22:04:50 UTC
Linux 5.14
Linux 5.14
Tip revision: 7d2a07b
time.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/arch/ia64/kernel/time.c
*
* Copyright (C) 1998-2003 Hewlett-Packard Co
* Stephane Eranian <eranian@hpl.hp.com>
* David Mosberger <davidm@hpl.hp.com>
* Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
* Copyright (C) 1999-2000 VA Linux Systems
* Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
*/
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/profile.h>
#include <linux/sched.h>
#include <linux/time.h>
#include <linux/nmi.h>
#include <linux/interrupt.h>
#include <linux/efi.h>
#include <linux/timex.h>
#include <linux/timekeeper_internal.h>
#include <linux/platform_device.h>
#include <linux/sched/cputime.h>
#include <asm/delay.h>
#include <asm/efi.h>
#include <asm/hw_irq.h>
#include <asm/ptrace.h>
#include <asm/sal.h>
#include <asm/sections.h>
#include "fsyscall_gtod_data.h"
#include "irq.h"
static u64 itc_get_cycles(struct clocksource *cs);
struct fsyscall_gtod_data_t fsyscall_gtod_data;
struct itc_jitter_data_t itc_jitter_data;
volatile int time_keeper_id = 0; /* smp_processor_id() of time-keeper */
#ifdef CONFIG_IA64_DEBUG_IRQ
unsigned long last_cli_ip;
EXPORT_SYMBOL(last_cli_ip);
#endif
static struct clocksource clocksource_itc = {
.name = "itc",
.rating = 350,
.read = itc_get_cycles,
.mask = CLOCKSOURCE_MASK(64),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};
static struct clocksource *itc_clocksource;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
#include <linux/kernel_stat.h>
extern u64 cycle_to_nsec(u64 cyc);
void vtime_flush(struct task_struct *tsk)
{
struct thread_info *ti = task_thread_info(tsk);
u64 delta;
if (ti->utime)
account_user_time(tsk, cycle_to_nsec(ti->utime));
if (ti->gtime)
account_guest_time(tsk, cycle_to_nsec(ti->gtime));
if (ti->idle_time)
account_idle_time(cycle_to_nsec(ti->idle_time));
if (ti->stime) {
delta = cycle_to_nsec(ti->stime);
account_system_index_time(tsk, delta, CPUTIME_SYSTEM);
}
if (ti->hardirq_time) {
delta = cycle_to_nsec(ti->hardirq_time);
account_system_index_time(tsk, delta, CPUTIME_IRQ);
}
if (ti->softirq_time) {
delta = cycle_to_nsec(ti->softirq_time);
account_system_index_time(tsk, delta, CPUTIME_SOFTIRQ);
}
ti->utime = 0;
ti->gtime = 0;
ti->idle_time = 0;
ti->stime = 0;
ti->hardirq_time = 0;
ti->softirq_time = 0;
}
/*
* Called from the context switch with interrupts disabled, to charge all
* accumulated times to the current process, and to prepare accounting on
* the next process.
*/
void arch_vtime_task_switch(struct task_struct *prev)
{
struct thread_info *pi = task_thread_info(prev);
struct thread_info *ni = task_thread_info(current);
ni->ac_stamp = pi->ac_stamp;
ni->ac_stime = ni->ac_utime = 0;
}
/*
* Account time for a transition between system, hard irq or soft irq state.
* Note that this function is called with interrupts enabled.
*/
static __u64 vtime_delta(struct task_struct *tsk)
{
struct thread_info *ti = task_thread_info(tsk);
__u64 now, delta_stime;
WARN_ON_ONCE(!irqs_disabled());
now = ia64_get_itc();
delta_stime = now - ti->ac_stamp;
ti->ac_stamp = now;
return delta_stime;
}
void vtime_account_kernel(struct task_struct *tsk)
{
struct thread_info *ti = task_thread_info(tsk);
__u64 stime = vtime_delta(tsk);
if (tsk->flags & PF_VCPU)
ti->gtime += stime;
else
ti->stime += stime;
}
EXPORT_SYMBOL_GPL(vtime_account_kernel);
void vtime_account_idle(struct task_struct *tsk)
{
struct thread_info *ti = task_thread_info(tsk);
ti->idle_time += vtime_delta(tsk);
}
void vtime_account_softirq(struct task_struct *tsk)
{
struct thread_info *ti = task_thread_info(tsk);
ti->softirq_time += vtime_delta(tsk);
}
void vtime_account_hardirq(struct task_struct *tsk)
{
struct thread_info *ti = task_thread_info(tsk);
ti->hardirq_time += vtime_delta(tsk);
}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
static irqreturn_t
timer_interrupt (int irq, void *dev_id)
{
unsigned long new_itm;
if (cpu_is_offline(smp_processor_id())) {
return IRQ_HANDLED;
}
new_itm = local_cpu_data->itm_next;
if (!time_after(ia64_get_itc(), new_itm))
printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
ia64_get_itc(), new_itm);
while (1) {
new_itm += local_cpu_data->itm_delta;
legacy_timer_tick(smp_processor_id() == time_keeper_id);
local_cpu_data->itm_next = new_itm;
if (time_after(new_itm, ia64_get_itc()))
break;
/*
* Allow IPIs to interrupt the timer loop.
*/
local_irq_enable();
local_irq_disable();
}
do {
/*
* If we're too close to the next clock tick for
* comfort, we increase the safety margin by
* intentionally dropping the next tick(s). We do NOT
* update itm.next because that would force us to call
* xtime_update() which in turn would let our clock run
* too fast (with the potentially devastating effect
* of losing monotony of time).
*/
while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
new_itm += local_cpu_data->itm_delta;
ia64_set_itm(new_itm);
/* double check, in case we got hit by a (slow) PMI: */
} while (time_after_eq(ia64_get_itc(), new_itm));
return IRQ_HANDLED;
}
/*
* Encapsulate access to the itm structure for SMP.
*/
void
ia64_cpu_local_tick (void)
{
int cpu = smp_processor_id();
unsigned long shift = 0, delta;
/* arrange for the cycle counter to generate a timer interrupt: */
ia64_set_itv(IA64_TIMER_VECTOR);
delta = local_cpu_data->itm_delta;
/*
* Stagger the timer tick for each CPU so they don't occur all at (almost) the
* same time:
*/
if (cpu) {
unsigned long hi = 1UL << ia64_fls(cpu);
shift = (2*(cpu - hi) + 1) * delta/hi/2;
}
local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
ia64_set_itm(local_cpu_data->itm_next);
}
static int nojitter;
static int __init nojitter_setup(char *str)
{
nojitter = 1;
printk("Jitter checking for ITC timers disabled\n");
return 1;
}
__setup("nojitter", nojitter_setup);
void ia64_init_itm(void)
{
unsigned long platform_base_freq, itc_freq;
struct pal_freq_ratio itc_ratio, proc_ratio;
long status, platform_base_drift, itc_drift;
/*
* According to SAL v2.6, we need to use a SAL call to determine the platform base
* frequency and then a PAL call to determine the frequency ratio between the ITC
* and the base frequency.
*/
status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
&platform_base_freq, &platform_base_drift);
if (status != 0) {
printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
} else {
status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
if (status != 0)
printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
}
if (status != 0) {
/* invent "random" values */
printk(KERN_ERR
"SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
platform_base_freq = 100000000;
platform_base_drift = -1; /* no drift info */
itc_ratio.num = 3;
itc_ratio.den = 1;
}
if (platform_base_freq < 40000000) {
printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
platform_base_freq);
platform_base_freq = 75000000;
platform_base_drift = -1;
}
if (!proc_ratio.den)
proc_ratio.den = 1; /* avoid division by zero */
if (!itc_ratio.den)
itc_ratio.den = 1; /* avoid division by zero */
itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%u/%u, "
"ITC freq=%lu.%03luMHz", smp_processor_id(),
platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
if (platform_base_drift != -1) {
itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
printk("+/-%ldppm\n", itc_drift);
} else {
itc_drift = -1;
printk("\n");
}
local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
local_cpu_data->itc_freq = itc_freq;
local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
+ itc_freq/2)/itc_freq;
if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
#ifdef CONFIG_SMP
/* On IA64 in an SMP configuration ITCs are never accurately synchronized.
* Jitter compensation requires a cmpxchg which may limit
* the scalability of the syscalls for retrieving time.
* The ITC synchronization is usually successful to within a few
* ITC ticks but this is not a sure thing. If you need to improve
* timer performance in SMP situations then boot the kernel with the
* "nojitter" option. However, doing so may result in time fluctuating (maybe
* even going backward) if the ITC offsets between the individual CPUs
* are too large.
*/
if (!nojitter)
itc_jitter_data.itc_jitter = 1;
#endif
} else
/*
* ITC is drifty and we have not synchronized the ITCs in smpboot.c.
* ITC values may fluctuate significantly between processors.
* Clock should not be used for hrtimers. Mark itc as only
* useful for boot and testing.
*
* Note that jitter compensation is off! There is no point of
* synchronizing ITCs since they may be large differentials
* that change over time.
*
* The only way to fix this would be to repeatedly sync the
* ITCs. Until that time we have to avoid ITC.
*/
clocksource_itc.rating = 50;
/* avoid softlock up message when cpu is unplug and plugged again. */
touch_softlockup_watchdog();
/* Setup the CPU local timer tick */
ia64_cpu_local_tick();
if (!itc_clocksource) {
clocksource_register_hz(&clocksource_itc,
local_cpu_data->itc_freq);
itc_clocksource = &clocksource_itc;
}
}
static u64 itc_get_cycles(struct clocksource *cs)
{
unsigned long lcycle, now, ret;
if (!itc_jitter_data.itc_jitter)
return get_cycles();
lcycle = itc_jitter_data.itc_lastcycle;
now = get_cycles();
if (lcycle && time_after(lcycle, now))
return lcycle;
/*
* Keep track of the last timer value returned.
* In an SMP environment, you could lose out in contention of
* cmpxchg. If so, your cmpxchg returns new value which the
* winner of contention updated to. Use the new value instead.
*/
ret = cmpxchg(&itc_jitter_data.itc_lastcycle, lcycle, now);
if (unlikely(ret != lcycle))
return ret;
return now;
}
void read_persistent_clock64(struct timespec64 *ts)
{
efi_gettimeofday(ts);
}
void __init
time_init (void)
{
register_percpu_irq(IA64_TIMER_VECTOR, timer_interrupt, IRQF_IRQPOLL,
"timer");
ia64_init_itm();
}
/*
* Generic udelay assumes that if preemption is allowed and the thread
* migrates to another CPU, that the ITC values are synchronized across
* all CPUs.
*/
static void
ia64_itc_udelay (unsigned long usecs)
{
unsigned long start = ia64_get_itc();
unsigned long end = start + usecs*local_cpu_data->cyc_per_usec;
while (time_before(ia64_get_itc(), end))
cpu_relax();
}
void (*ia64_udelay)(unsigned long usecs) = &ia64_itc_udelay;
void
udelay (unsigned long usecs)
{
(*ia64_udelay)(usecs);
}
EXPORT_SYMBOL(udelay);
/* IA64 doesn't cache the timezone */
void update_vsyscall_tz(void)
{
}
void update_vsyscall(struct timekeeper *tk)
{
write_seqcount_begin(&fsyscall_gtod_data.seq);
/* copy vsyscall data */
fsyscall_gtod_data.clk_mask = tk->tkr_mono.mask;
fsyscall_gtod_data.clk_mult = tk->tkr_mono.mult;
fsyscall_gtod_data.clk_shift = tk->tkr_mono.shift;
fsyscall_gtod_data.clk_fsys_mmio = tk->tkr_mono.clock->archdata.fsys_mmio;
fsyscall_gtod_data.clk_cycle_last = tk->tkr_mono.cycle_last;
fsyscall_gtod_data.wall_time.sec = tk->xtime_sec;
fsyscall_gtod_data.wall_time.snsec = tk->tkr_mono.xtime_nsec;
fsyscall_gtod_data.monotonic_time.sec = tk->xtime_sec
+ tk->wall_to_monotonic.tv_sec;
fsyscall_gtod_data.monotonic_time.snsec = tk->tkr_mono.xtime_nsec
+ ((u64)tk->wall_to_monotonic.tv_nsec
<< tk->tkr_mono.shift);
/* normalize */
while (fsyscall_gtod_data.monotonic_time.snsec >=
(((u64)NSEC_PER_SEC) << tk->tkr_mono.shift)) {
fsyscall_gtod_data.monotonic_time.snsec -=
((u64)NSEC_PER_SEC) << tk->tkr_mono.shift;
fsyscall_gtod_data.monotonic_time.sec++;
}
write_seqcount_end(&fsyscall_gtod_data.seq);
}