kernel: implement cpu IDs and per-cpu variables

kernel/cpu.c

@@ -0,0 +1,41 @@
+#include <socks/cpu.h>
+#include <socks/percpu.h>
+#include <socks/bitmap.h>
+
+DECLARE_BITMAP(cpu_available, CPU_MAX);
+DECLARE_BITMAP(cpu_online, CPU_MAX);
+
+DEFINE_PERCPU_VAR(cpu_data_t, cpu_data);
+
+cpu_data_t *get_this_cpu(void)
+{
+	return percpu_get(&cpu_data);
+}
+
+void put_cpu(cpu_data_t *cpu)
+{
+	percpu_put(cpu);
+}
+
+void cpu_set_available(unsigned int cpu_id)
+{
+	if (cpu_id >= CPU_MAX) {
+		return;
+	}
+
+	bitmap_set(cpu_available, cpu_id);
+}
+
+void cpu_set_online(unsigned int cpu_id)
+{
+	if (cpu_id >= CPU_MAX) {
+		return;
+	}
+
+	bitmap_set(cpu_online, cpu_id);
+}
+
+unsigned int cpu_get_highest_available(void)
+{
+	return bitmap_highest_set(cpu_available, CPU_MAX);
+}

kernel/percpu.c

@@ -0,0 +1,40 @@
+#include <socks/percpu.h>
+#include <socks/cpu.h>
+#include <socks/vm.h>
+#include <stdint.h>
+#include <stddef.h>
+
+extern char __percpu_start[];
+extern char __percpu_end[];
+
+static void *percpu_buffer = NULL;
+static size_t percpu_stride = 0;
+
+extern kern_status_t init_per_cpu_areas(void)
+{
+	unsigned int last_cpu = cpu_get_highest_available();
+
+	percpu_stride = (uintptr_t)__percpu_end - (uintptr_t)__percpu_start;
+	if (percpu_stride & 0x7) {
+		percpu_stride &= ~0x7;
+		percpu_stride += 0x8;
+	}
+
+	percpu_buffer = kmalloc(last_cpu * percpu_stride, 0);
+	return KERN_OK;
+}
+
+extern void *__percpu_get(void *var)
+{
+	uintptr_t pvar = (uintptr_t)var;
+	uintptr_t percpu_start = (uintptr_t)__percpu_start;
+	uintptr_t percpu_end = (uintptr_t)__percpu_end;
+
+	if (pvar < percpu_start || pvar >= percpu_end) {
+		return NULL;
+	}
+
+	size_t var_offset = pvar - percpu_start;
+
+	return (char *)percpu_buffer + (this_cpu() * percpu_stride) + var_offset;
+}