CheckP: smp support

src/sys/spinlock.h

@@ -0,0 +1,62 @@
+// Copyright (c) 2023-2026 Chris (boreddevnl)
+// This software is released under the GNU General Public License v3.0. See LICENSE file for details.
+// This header needs to maintain in any file it is present in, as per the GPL license terms.
+#ifndef SPINLOCK_H
+#define SPINLOCK_H
+
+#include <stdint.h>
+
+// Simple test-and-set spinlock for x86_64 SMP.
+// Uses 'lock xchg' for acquire and a plain store for release.
+// Includes 'pause' to reduce bus contention while spinning.
+
+typedef volatile uint32_t spinlock_t;
+
+#define SPINLOCK_INIT 0
+
+static inline void spinlock_acquire(spinlock_t *lock) {
+    while (1) {
+        // Try to set the lock from 0 -> 1
+        uint32_t prev;
+        asm volatile("lock xchgl %0, %1"
+                     : "=r"(prev), "+m"(*lock)
+                     : "0"((uint32_t)1)
+                     : "memory");
+        if (prev == 0) return; // We got the lock
+        // Spin with pause (reduces power and bus traffic)
+        while (*lock) {
+            asm volatile("pause" ::: "memory");
+        }
+    }
+}
+
+static inline void spinlock_release(spinlock_t *lock) {
+    asm volatile("" ::: "memory"); // compiler barrier
+    *lock = 0;
+}
+
+// Try to acquire without blocking. Returns 1 if acquired, 0 if not.
+static inline int spinlock_try(spinlock_t *lock) {
+    uint32_t prev;
+    asm volatile("lock xchgl %0, %1"
+                 : "=r"(prev), "+m"(*lock)
+                 : "0"((uint32_t)1)
+                 : "memory");
+    return (prev == 0);
+}
+
+// IRQ-safe spinlock: saves flags, disables interrupts, then acquires.
+// Use when the lock may be contended from interrupt context.
+static inline uint64_t spinlock_acquire_irqsave(spinlock_t *lock) {
+    uint64_t flags;
+    asm volatile("pushfq; pop %0; cli" : "=r"(flags) :: "memory");
+    spinlock_acquire(lock);
+    return flags;
+}
+
+static inline void spinlock_release_irqrestore(spinlock_t *lock, uint64_t flags) {
+    spinlock_release(lock);
+    asm volatile("push %0; popfq" : : "r"(flags) : "memory");
+}
+
+#endif