58 lines
1.2 KiB
C
58 lines
1.2 KiB
C
#include <stdatomic.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include "spinlock/spinlock.h"
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#include "kprintf.h"
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#define SPINLOCK_HINT() asm volatile("pause")
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struct {
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uint64_t irq_flags;
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atomic_int irq_nest;
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} IRQ_CTX = {0};
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void spinlock_init(SpinLock *sl) {
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atomic_clear_flag_explicit(&sl->lock, memory_order_relaxed);
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}
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uint64_t irqsave(void) {
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uint64_t flags;
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asm volatile("pushfq; cli; popq %0" : "=r"(flags) :: "memory", "cc");
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return flags;
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}
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void irqrestore(uint64_t flags) {
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if (flags & (1ULL << 9)) {
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asm volatile("sti" ::: "memory", "cc");
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}
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}
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void irqsave_nested(void) {
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int prev = atomic_fetch_add_explicit(&IRQ_CTX.irq_nest, 1, memory_order_acq_rel);
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if (prev == 0) {
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IRQ_CTX.irq_flags = irqsave();
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}
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}
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void irqrestore_nested(void) {
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int prev = atomic_fetch_sub_explicit(&IRQ_CTX.irq_nest, 1, memory_order_acq_rel);
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if (prev == 1) {
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irqrestore(IRQ_CTX.irq_flags);
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}
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}
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void spinlock_acquire(SpinLock *sl) {
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irqsave_nested();
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while (atomic_test_and_set_explicit(&sl->lock, memory_order_acquire)) {
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SPINLOCK_HINT();
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}
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}
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void spinlock_release(SpinLock *sl) {
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atomic_clear_flag_explicit(&sl->lock, memory_order_release);
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irqrestore_nested();
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}
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