cpu: cpu_cache_line_size

kernel-src/arch/x86-64/cpu.c

@@ -18,6 +18,21 @@
 static bool has_smap;
 static bool has_smap_detected;
 static bool has_smep;
+static size_t cache_line_size;
+
+size_t cpu_cache_line_size(void) {
+	size_t size = cache_line_size;
+	if (size)
+		return size;
+
+	uint32_t eax, ebx, ecx, edx;
+	__assert(__get_cpuid(1, &eax, &ebx, &ecx, &edx));
+	size = ((ebx >> 8) & 0xff) * 8;
+	__assert(size);
+
+	cache_line_size = size;
+	return size;
+}
 
 void arch_syscall_entry();
 static void illisr(isr_t *self, context_t *ctx) {

kernel-src/include/x86-64/arch/cpu.h

@@ -114,6 +114,7 @@ static inline uint16_t be_to_cpu_w(uint16_t w) {
 }
 
 cpu_t *get_bsp(void);
+size_t cpu_cache_line_size(void);
 void arch_cpu_user_access_begin(void);
 void arch_cpu_user_access_end(void);
 bool arch_cpu_smep_enabled(void);