feat: add support for aarch64 timer/interrupts, port MontaukOS userspace

programs/lib/libc/crt/crt1.c

@@ -8,6 +8,8 @@
     * calls main(), then exits with main()'s return code.
 */
 
+#if defined(__x86_64__)
+
 static inline long _sys1(long nr, long a1) {
     long ret;
     __asm__ volatile(
@@ -31,6 +33,27 @@ static inline long _sys2(long nr, long a1, long a2) {
     return ret;
 }
 
+#elif defined(__aarch64__)
+
+static inline long _sys1(long nr, long a1) {
+    register long x8 __asm__("x8") = nr;
+    register long x0 __asm__("x0") = a1;
+    __asm__ volatile("svc #0" : "+r"(x0) : "r"(x8) : "memory");
+    return x0;
+}
+
+static inline long _sys2(long nr, long a1, long a2) {
+    register long x8 __asm__("x8") = nr;
+    register long x0 __asm__("x0") = a1;
+    register long x1 __asm__("x1") = a2;
+    __asm__ volatile("svc #0" : "+r"(x0) : "r"(x8), "r"(x1) : "memory");
+    return x0;
+}
+
+#else
+#error "unsupported architecture"
+#endif
+
 #define SYS_EXIT        0
 #define SYS_GETARGS     25
 #define SYS_GETEXECPATH 151