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

programs/include/libc/montauk.h

@@ -419,6 +419,8 @@ typedef struct {
    Raw syscall wrappers
    ==================================================================== */
 
+#if defined(__x86_64__)
+
 static inline long _mtk_syscall0(long nr) {
     long ret;
     __asm__ volatile("syscall" : "=a"(ret) : "a"(nr)
@@ -491,6 +493,66 @@ static inline long _mtk_syscall5(long nr, long a1, long a2, long a3, long a4, lo
     return ret;
 }
 
+#elif defined(__aarch64__)
+
+// AArch64: number in x8, arguments in x0-x5, `svc #0`; the kernel
+// preserves every register except x0, which carries the result.
+static inline long _mtk_syscall0(long nr) {
+    register long x8 __asm__("x8") = nr;
+    register long x0 __asm__("x0");
+    __asm__ volatile("svc #0" : "=r"(x0) : "r"(x8) : "memory");
+    return x0;
+}
+
+static inline long _mtk_syscall1(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 _mtk_syscall2(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;
+}
+
+static inline long _mtk_syscall3(long nr, long a1, long a2, long a3) {
+    register long x8 __asm__("x8") = nr;
+    register long x0 __asm__("x0") = a1;
+    register long x1 __asm__("x1") = a2;
+    register long x2 __asm__("x2") = a3;
+    __asm__ volatile("svc #0" : "+r"(x0) : "r"(x8), "r"(x1), "r"(x2) : "memory");
+    return x0;
+}
+
+static inline long _mtk_syscall4(long nr, long a1, long a2, long a3, long a4) {
+    register long x8 __asm__("x8") = nr;
+    register long x0 __asm__("x0") = a1;
+    register long x1 __asm__("x1") = a2;
+    register long x2 __asm__("x2") = a3;
+    register long x3 __asm__("x3") = a4;
+    __asm__ volatile("svc #0" : "+r"(x0) : "r"(x8), "r"(x1), "r"(x2), "r"(x3) : "memory");
+    return x0;
+}
+
+static inline long _mtk_syscall5(long nr, long a1, long a2, long a3, long a4, long a5) {
+    register long x8 __asm__("x8") = nr;
+    register long x0 __asm__("x0") = a1;
+    register long x1 __asm__("x1") = a2;
+    register long x2 __asm__("x2") = a3;
+    register long x3 __asm__("x3") = a4;
+    register long x4 __asm__("x4") = a5;
+    __asm__ volatile("svc #0" : "+r"(x0) : "r"(x8), "r"(x1), "r"(x2), "r"(x3), "r"(x4) : "memory");
+    return x0;
+}
+
+#else
+#error "unsupported architecture"
+#endif
+
 /* ====================================================================
    Process management
    ==================================================================== */

programs/include/libc/setjmp.h

@@ -7,7 +7,11 @@
 extern "C" {
 #endif
 
-typedef unsigned long jmp_buf[8];
+#if defined(__aarch64__)
+typedef unsigned long jmp_buf[21];  /* x19-x30, sp, d8-d15 */
+#else
+typedef unsigned long jmp_buf[8];   /* rbx, rbp, r12-r15, rsp, rip */
+#endif
 
 int  setjmp(jmp_buf env);
 void longjmp(jmp_buf env, int val) __attribute__((noreturn));