ladybird/Kernel/Time/TimeManagement.cpp
Gunnar Beutner 52a4a1ec75 Kernel: Fix return value for {enable,disable}_profile_timer()
These functions should return success when being called when profiling
has been requested from multiple callers because enabling/disabling the
timer is a no-op in that case and thus didn't fail.
2021-05-17 21:53:04 +02:00

422 lines
14 KiB
C++

/*
* Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/Singleton.h>
#include <AK/StdLibExtras.h>
#include <AK/Time.h>
#include <Kernel/ACPI/Parser.h>
#include <Kernel/CommandLine.h>
#include <Kernel/Interrupts/APIC.h>
#include <Kernel/PerformanceManager.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Time/APICTimer.h>
#include <Kernel/Time/HPET.h>
#include <Kernel/Time/HPETComparator.h>
#include <Kernel/Time/HardwareTimer.h>
#include <Kernel/Time/PIT.h>
#include <Kernel/Time/RTC.h>
#include <Kernel/Time/TimeManagement.h>
#include <Kernel/TimerQueue.h>
#include <Kernel/VM/MemoryManager.h>
namespace Kernel {
static AK::Singleton<TimeManagement> s_the;
TimeManagement& TimeManagement::the()
{
return *s_the;
}
bool TimeManagement::is_valid_clock_id(clockid_t clock_id)
{
switch (clock_id) {
case CLOCK_MONOTONIC:
case CLOCK_MONOTONIC_COARSE:
case CLOCK_MONOTONIC_RAW:
case CLOCK_REALTIME:
case CLOCK_REALTIME_COARSE:
return true;
default:
return false;
};
}
Time TimeManagement::current_time(clockid_t clock_id) const
{
switch (clock_id) {
case CLOCK_MONOTONIC:
return monotonic_time(TimePrecision::Precise);
case CLOCK_MONOTONIC_COARSE:
return monotonic_time(TimePrecision::Coarse);
case CLOCK_MONOTONIC_RAW:
return monotonic_time_raw();
case CLOCK_REALTIME:
return epoch_time(TimePrecision::Precise);
case CLOCK_REALTIME_COARSE:
return epoch_time(TimePrecision::Coarse);
default:
// Syscall entrypoint is missing a is_valid_clock_id(..) check?
VERIFY_NOT_REACHED();
}
}
bool TimeManagement::is_system_timer(const HardwareTimerBase& timer) const
{
return &timer == m_system_timer.ptr();
}
void TimeManagement::set_epoch_time(Time ts)
{
InterruptDisabler disabler;
// FIXME: Should use AK::Time internally
m_epoch_time = ts.to_timespec();
m_remaining_epoch_time_adjustment = { 0, 0 };
}
Time TimeManagement::monotonic_time(TimePrecision precision) const
{
// This is the time when last updated by an interrupt.
u64 seconds;
u32 ticks;
bool do_query = precision == TimePrecision::Precise && m_can_query_precise_time;
u32 update_iteration;
do {
update_iteration = m_update1.load(AK::MemoryOrder::memory_order_acquire);
seconds = m_seconds_since_boot;
ticks = m_ticks_this_second;
if (do_query) {
// We may have to do this over again if the timer interrupt fires
// while we're trying to query the information. In that case, our
// seconds and ticks became invalid, producing an incorrect time.
// Be sure to not modify m_seconds_since_boot and m_ticks_this_second
// because this may only be modified by the interrupt handler
HPET::the().update_time(seconds, ticks, true);
}
} while (update_iteration != m_update2.load(AK::MemoryOrder::memory_order_acquire));
VERIFY(m_time_ticks_per_second > 0);
VERIFY(ticks < m_time_ticks_per_second);
u64 ns = ((u64)ticks * 1000000000ull) / m_time_ticks_per_second;
VERIFY(ns < 1000000000ull);
return Time::from_timespec({ (i64)seconds, (i32)ns });
}
Time TimeManagement::epoch_time(TimePrecision) const
{
// TODO: Take into account precision
timespec ts;
u32 update_iteration;
do {
update_iteration = m_update1.load(AK::MemoryOrder::memory_order_acquire);
ts = m_epoch_time;
} while (update_iteration != m_update2.load(AK::MemoryOrder::memory_order_acquire));
return Time::from_timespec(ts);
}
u64 TimeManagement::uptime_ms() const
{
auto mtime = monotonic_time().to_timespec();
// This overflows after 292 million years of uptime.
// Since this is only used for performance timestamps and sys$times, that's probably enough.
u64 ms = mtime.tv_sec * 1000ull;
ms += mtime.tv_nsec / 1000000;
return ms;
}
UNMAP_AFTER_INIT void TimeManagement::initialize(u32 cpu)
{
if (cpu == 0) {
VERIFY(!s_the.is_initialized());
s_the.ensure_instance();
// Initialize the APIC timers after the other timers as the
// initialization needs to briefly enable interrupts, which then
// would trigger a deadlock trying to get the s_the instance while
// creating it.
if (auto* apic_timer = APIC::the().initialize_timers(*s_the->m_system_timer)) {
dmesgln("Time: Using APIC timer as system timer");
s_the->set_system_timer(*apic_timer);
}
} else {
VERIFY(s_the.is_initialized());
if (auto* apic_timer = APIC::the().get_timer()) {
dmesgln("Time: Enable APIC timer on CPU #{}", cpu);
apic_timer->enable_local_timer();
}
}
}
void TimeManagement::set_system_timer(HardwareTimerBase& timer)
{
VERIFY(Processor::is_bootstrap_processor()); // This should only be called on the BSP!
auto original_callback = m_system_timer->set_callback(nullptr);
m_system_timer->disable();
timer.set_callback(move(original_callback));
m_system_timer = timer;
}
time_t TimeManagement::ticks_per_second() const
{
return m_time_keeper_timer->ticks_per_second();
}
time_t TimeManagement::boot_time() const
{
return RTC::boot_time();
}
UNMAP_AFTER_INIT TimeManagement::TimeManagement()
{
bool probe_non_legacy_hardware_timers = !(kernel_command_line().is_legacy_time_enabled());
if (ACPI::is_enabled()) {
if (!ACPI::Parser::the()->x86_specific_flags().cmos_rtc_not_present) {
RTC::initialize();
m_epoch_time.tv_sec += boot_time();
} else {
dmesgln("ACPI: RTC CMOS Not present");
}
} else {
// We just assume that we can access RTC CMOS, if ACPI isn't usable.
RTC::initialize();
m_epoch_time.tv_sec += boot_time();
}
if (probe_non_legacy_hardware_timers) {
if (!probe_and_set_non_legacy_hardware_timers())
if (!probe_and_set_legacy_hardware_timers())
VERIFY_NOT_REACHED();
} else if (!probe_and_set_legacy_hardware_timers()) {
VERIFY_NOT_REACHED();
}
}
Time TimeManagement::now()
{
return s_the.ptr()->epoch_time();
}
UNMAP_AFTER_INIT Vector<HardwareTimerBase*> TimeManagement::scan_and_initialize_periodic_timers()
{
bool should_enable = is_hpet_periodic_mode_allowed();
dbgln("Time: Scanning for periodic timers");
Vector<HardwareTimerBase*> timers;
for (auto& hardware_timer : m_hardware_timers) {
if (hardware_timer.is_periodic_capable()) {
timers.append(&hardware_timer);
if (should_enable)
hardware_timer.set_periodic();
}
}
return timers;
}
UNMAP_AFTER_INIT Vector<HardwareTimerBase*> TimeManagement::scan_for_non_periodic_timers()
{
dbgln("Time: Scanning for non-periodic timers");
Vector<HardwareTimerBase*> timers;
for (auto& hardware_timer : m_hardware_timers) {
if (!hardware_timer.is_periodic_capable())
timers.append(&hardware_timer);
}
return timers;
}
bool TimeManagement::is_hpet_periodic_mode_allowed()
{
switch (kernel_command_line().hpet_mode()) {
case HPETMode::Periodic:
return true;
case HPETMode::NonPeriodic:
return false;
default:
VERIFY_NOT_REACHED();
}
}
UNMAP_AFTER_INIT bool TimeManagement::probe_and_set_non_legacy_hardware_timers()
{
if (!ACPI::is_enabled())
return false;
if (!HPET::test_and_initialize())
return false;
if (!HPET::the().comparators().size()) {
dbgln("HPET initialization aborted.");
return false;
}
dbgln("HPET: Setting appropriate functions to timers.");
for (auto& hpet_comparator : HPET::the().comparators())
m_hardware_timers.append(hpet_comparator);
auto periodic_timers = scan_and_initialize_periodic_timers();
auto non_periodic_timers = scan_for_non_periodic_timers();
if (is_hpet_periodic_mode_allowed())
VERIFY(!periodic_timers.is_empty());
VERIFY(periodic_timers.size() + non_periodic_timers.size() > 0);
size_t taken_periodic_timers_count = 0;
size_t taken_non_periodic_timers_count = 0;
if (periodic_timers.size() > taken_periodic_timers_count) {
m_system_timer = periodic_timers[taken_periodic_timers_count];
taken_periodic_timers_count += 1;
} else if (non_periodic_timers.size() > taken_non_periodic_timers_count) {
m_system_timer = non_periodic_timers[taken_non_periodic_timers_count];
taken_non_periodic_timers_count += 1;
}
m_system_timer->set_callback([this](const RegisterState& regs) {
// Update the time. We don't really care too much about the
// frequency of the interrupt because we'll query the main
// counter to get an accurate time.
if (Processor::is_bootstrap_processor()) {
// TODO: Have the other CPUs call system_timer_tick directly
increment_time_since_boot_hpet();
}
system_timer_tick(regs);
});
// Use the HPET main counter frequency for time purposes. This is likely
// a much higher frequency than the interrupt itself and allows us to
// keep a more accurate time
m_can_query_precise_time = true;
m_time_ticks_per_second = HPET::the().frequency();
m_system_timer->try_to_set_frequency(m_system_timer->calculate_nearest_possible_frequency(OPTIMAL_TICKS_PER_SECOND_RATE));
// We don't need an interrupt for time keeping purposes because we
// can query the timer.
m_time_keeper_timer = m_system_timer;
if (periodic_timers.size() > taken_periodic_timers_count) {
m_profile_timer = periodic_timers[taken_periodic_timers_count];
taken_periodic_timers_count += 1;
} else if (non_periodic_timers.size() > taken_non_periodic_timers_count) {
m_profile_timer = non_periodic_timers[taken_non_periodic_timers_count];
taken_non_periodic_timers_count += 1;
}
if (m_profile_timer) {
m_profile_timer->set_callback(PerformanceManager::timer_tick);
m_profile_timer->try_to_set_frequency(m_profile_timer->calculate_nearest_possible_frequency(1));
}
return true;
}
UNMAP_AFTER_INIT bool TimeManagement::probe_and_set_legacy_hardware_timers()
{
if (ACPI::is_enabled()) {
if (ACPI::Parser::the()->x86_specific_flags().cmos_rtc_not_present) {
dbgln("ACPI: CMOS RTC Not Present");
return false;
} else {
dbgln("ACPI: CMOS RTC Present");
}
}
m_hardware_timers.append(PIT::initialize(TimeManagement::update_time));
m_hardware_timers.append(RealTimeClock::create(TimeManagement::system_timer_tick));
m_time_keeper_timer = m_hardware_timers[0];
m_system_timer = m_hardware_timers[1];
// The timer is only as accurate as the interrupts...
m_time_ticks_per_second = m_time_keeper_timer->ticks_per_second();
return true;
}
void TimeManagement::update_time(const RegisterState&)
{
TimeManagement::the().increment_time_since_boot();
}
void TimeManagement::increment_time_since_boot_hpet()
{
VERIFY(!m_time_keeper_timer.is_null());
VERIFY(m_time_keeper_timer->timer_type() == HardwareTimerType::HighPrecisionEventTimer);
// NOTE: m_seconds_since_boot and m_ticks_this_second are only ever
// updated here! So we can safely read that information, query the clock,
// and when we're all done we can update the information. This reduces
// contention when other processors attempt to read the clock.
auto seconds_since_boot = m_seconds_since_boot;
auto ticks_this_second = m_ticks_this_second;
auto delta_ns = HPET::the().update_time(seconds_since_boot, ticks_this_second, false);
// Now that we have a precise time, go update it as quickly as we can
u32 update_iteration = m_update1.fetch_add(1, AK::MemoryOrder::memory_order_acquire);
m_seconds_since_boot = seconds_since_boot;
m_ticks_this_second = ticks_this_second;
// TODO: Apply m_remaining_epoch_time_adjustment
timespec_add(m_epoch_time, { (time_t)(delta_ns / 1000000000), (long)(delta_ns % 1000000000) }, m_epoch_time);
m_update2.store(update_iteration + 1, AK::MemoryOrder::memory_order_release);
}
void TimeManagement::increment_time_since_boot()
{
VERIFY(!m_time_keeper_timer.is_null());
// Compute time adjustment for adjtime. Let the clock run up to 1% fast or slow.
// That way, adjtime can adjust up to 36 seconds per hour, without time getting very jumpy.
// Once we have a smarter NTP service that also adjusts the frequency instead of just slewing time, maybe we can lower this.
long NanosPerTick = 1'000'000'000 / m_time_keeper_timer->frequency();
time_t MaxSlewNanos = NanosPerTick / 100;
u32 update_iteration = m_update1.fetch_add(1, AK::MemoryOrder::memory_order_acquire);
// Clamp twice, to make sure intermediate fits into a long.
long slew_nanos = clamp(clamp(m_remaining_epoch_time_adjustment.tv_sec, (time_t)-1, (time_t)1) * 1'000'000'000 + m_remaining_epoch_time_adjustment.tv_nsec, -MaxSlewNanos, MaxSlewNanos);
timespec slew_nanos_ts;
timespec_sub({ 0, slew_nanos }, { 0, 0 }, slew_nanos_ts); // Normalize tv_nsec to be positive.
timespec_sub(m_remaining_epoch_time_adjustment, slew_nanos_ts, m_remaining_epoch_time_adjustment);
timespec epoch_tick = { .tv_sec = 0, .tv_nsec = NanosPerTick };
epoch_tick.tv_nsec += slew_nanos; // No need for timespec_add(), guaranteed to be in range.
timespec_add(m_epoch_time, epoch_tick, m_epoch_time);
if (++m_ticks_this_second >= m_time_keeper_timer->ticks_per_second()) {
// FIXME: Synchronize with other clock somehow to prevent drifting apart.
++m_seconds_since_boot;
m_ticks_this_second = 0;
}
m_update2.store(update_iteration + 1, AK::MemoryOrder::memory_order_release);
}
void TimeManagement::system_timer_tick(const RegisterState& regs)
{
if (Processor::current().in_irq() <= 1) {
// Don't expire timers while handling IRQs
TimerQueue::the().fire();
}
Scheduler::timer_tick(regs);
}
bool TimeManagement::enable_profile_timer()
{
if (!m_profile_timer)
return false;
if (m_profile_enable_count.fetch_add(1) == 0)
return m_profile_timer->try_to_set_frequency(m_profile_timer->calculate_nearest_possible_frequency(OPTIMAL_PROFILE_TICKS_PER_SECOND_RATE));
return true;
}
bool TimeManagement::disable_profile_timer()
{
if (!m_profile_timer)
return false;
if (m_profile_enable_count.fetch_sub(1) == 1)
return m_profile_timer->try_to_set_frequency(m_profile_timer->calculate_nearest_possible_frequency(1));
return true;
}
}