spinlock.c

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/*
 * PROJECT:      MatanelOS Kernel
 * LICENSE:      GPLv3
 * PURPOSE:      Spinlock Types and Function Declarations. (MS)
 */
#ifndef X86_SPINLOCK_H
#define X86_SPINLOCK_H
 
#include "../../includes/ms.h"
#include "../../includes/me.h"
 
void 
MsAcquireSpinlock (
    IN    PSPINLOCK lock,
    IN    PIRQL OldIrql
) 
 
/*++
 
    Routine description : Acquires a spinlock, raises IRQL to DISPATCH_LEVEL.
 
    Arguments:
 
        [IN]    Pointer to SPINLOCK object.
        [IN]    Pointer to Old IRQL variable.
 
    Return Values:
 
        None.
 
--*/
 
{
    if (!lock) return;
    // spin until we grab the lock.
    MeRaiseIrql(DISPATCH_LEVEL, OldIrql);
    while (__sync_lock_test_and_set(&lock->locked, 1)) {
        __asm__ volatile("pause" ::: "memory"); /* x86 pause — CPU relax hint */
    }
    // Memory barrier to prevent instruction reordering
    __asm__ volatile("" ::: "memory");
}
 
void 
MsReleaseSpinlock (
    IN    PSPINLOCK lock, 
    IN    IRQL OldIrql
) 
 
/*++
 
    Routine description : Releases a spinlock, restores previous IRQL.
 
    Arguments:
 
        [IN]    Pointer to SPINLOCK object.
        [IN]    Old IRQL given by MsAcquireSpinlock
 
    Return Values:
 
        None.
 
--*/
 
{
    if (!lock) return;
    // Memory barrier before release
    __asm__ volatile("" ::: "memory");
    __sync_lock_release(&lock->locked);
    MeLowerIrql(OldIrql);
}
 
void
MsAcquireSpinlockAtDpcLevel(
    IN PSPINLOCK Lock
)
 
{
    // Make sure we are at DPC level or above
    if (MeGetCurrentIrql() < DISPATCH_LEVEL) {
        // Bugcheck.
        MeBugCheckEx(
            IRQL_NOT_GREATER_OR_EQUAL,
            (void*)Lock,
            (void*)MeGetCurrentIrql(),
            NULL,
            NULL
        );
    }
    
    // Acquire the spinlock.
    while (__sync_lock_test_and_set(&Lock->locked, 1)) {
        __asm__ volatile("pause" ::: "memory"); /* x86 pause — CPU relax hint */
    }
    // Memory barrier to prevent instruction reordering
    __asm__ volatile("" ::: "memory");
}
 
void
MsReleaseSpinlockFromDpcLevel(
    IN PSPINLOCK Lock
)
 
{
    // Make sure we are at DPC level or above
    if (MeGetCurrentIrql() < DISPATCH_LEVEL) {
        // Bugcheck.
        MeBugCheckEx(
            IRQL_NOT_GREATER_OR_EQUAL,
            (void*)Lock,
            (void*)MeGetCurrentIrql(),
            NULL,
            NULL
        );
    }
 
    // Release the spinlock.
    __asm__ volatile("" ::: "memory");
    __sync_lock_release(&Lock->locked);
}
 
#endif