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Kernel: All processors use LAPIC timer when running with APIC

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This makes scheduler preemption much cleaner as bsb does not have to
send smp messages to notify other processes about timer interrupt.

Also PIT percision is now "full" 0.8 us instead of 1 ms that I was using
before.
This commit is contained in:
Bananymous
2024-07-23 02:28:52 +03:00
parent 3e0150f847
commit 539afb329a
17 changed files with 224 additions and 73 deletions
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58
kernel/kernel/APIC.cpp
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@@ -17,6 +17,11 @@
#define LAPIC_ICR_LO_REG 0x300
#define LAPIC_ICR_HI_REG 0x310
#define LAPIC_TIMER_LVT 0x320
#define LAPIC_TIMER_INITIAL_REG 0x380
#define LAPIC_TIMER_CURRENT_REG 0x390
#define LAPIC_TIMER_DIVIDE_REG 0x3E0
#define IOAPIC_MAX_REDIRS 0x01
#define IOAPIC_REDIRS 0x10
@@ -60,6 +65,27 @@ namespace Kernel
ICR_LO_destination_shorthand_all_excluding_self = 0b11 << 18,
};
enum TimerLVT : uint32_t
{
TimerModeOneShot = 0b00 << 17,
TimerModePeriodic = 0b01 << 17,
TimerModeTSCDeadline = 0b10 << 17,
TimerMask = 1 << 16,
};
enum TimerDivideRegister : uint32_t
{
DivideBy2 = 0b0000,
DivideBy4 = 0b0001,
DivideBy8 = 0b0010,
DivideBy16 = 0b0011,
DivideBy32 = 0b1000,
DivideBy64 = 0b1001,
DivideBy128 = 0b1010,
DivideBy1 = 0b1011,
};
struct MADT : public Kernel::ACPI::SDTHeader
{
uint32_t local_apic;
@@ -223,12 +249,7 @@ namespace Kernel
void APIC::initialize_multiprocessor()
{
constexpr auto udelay =
[](uint64_t us) {
uint64_t wake_time = SystemTimer::get().ns_since_boot() + us * 1000;
while (SystemTimer::get().ns_since_boot() < wake_time)
__builtin_ia32_pause();
};
constexpr auto udelay = [](uint64_t us) { SystemTimer::get().pre_scheduler_sleep_ns(us * 1000); };
const auto send_ipi =
[&](uint8_t processor, uint32_t data, uint64_t ud)
@@ -367,6 +388,31 @@ namespace Kernel
void APIC::enable()
{
write_to_local_apic(LAPIC_SIV_REG, read_from_local_apic(LAPIC_SIV_REG) | 0x1FF);
initialize_timer();
}
static SpinLock s_timer_init_lock;
void APIC::initialize_timer()
{
{
constexpr uint64_t measuring_duration_ms = 100;
SpinLockGuard _(s_timer_init_lock);
write_to_local_apic(LAPIC_TIMER_LVT, TimerModeOneShot | TimerMask);
write_to_local_apic(LAPIC_TIMER_DIVIDE_REG, DivideBy2);
write_to_local_apic(LAPIC_TIMER_INITIAL_REG, 0xFFFFFFFF);
SystemTimer::get().pre_scheduler_sleep_ns(measuring_duration_ms * 1'000'000);
const uint32_t counter = read_from_local_apic(LAPIC_TIMER_CURRENT_REG);
m_lapic_timer_frequency_hz = static_cast<uint64_t>(0xFFFFFFFF - counter) * 2 * (1000 / measuring_duration_ms);
dprintln("CPU {}: lapic timer frequency: {} Hz", Kernel::Processor::current_id(), m_lapic_timer_frequency_hz);
}
write_to_local_apic(LAPIC_TIMER_LVT, TimerModePeriodic | (IRQ_VECTOR_BASE + IRQ_TIMER));
write_to_local_apic(LAPIC_TIMER_INITIAL_REG, m_lapic_timer_frequency_hz / 2 / 100);
}
uint32_t APIC::read_from_local_apic(ptrdiff_t offset)