For now, pass syscall arguments on the stack like in 32-bit.

455c6a88 · Silas Boyd-Wickizer · aa5825fc · 455c6a88
--- a/usys.S
+++ b/usys.S
@@ -4,8 +4,16 @@
 #define SYSCALL(name) \
  .globl name; \
  name: \
-    movl $SYS_ ## name, %eax; \
+    pushq %r9; \
+    pushq %r8; \
+    pushq %rcx; \
+    pushq %rdx; \
+    pushq %rsi; \
+    pushq %rdi; \
+    pushq $0; \
+    movq $SYS_ ## name, %rax; \
    int $T_SYSCALL; \
+    addq $(7 * 8), %rsp; \
    ret
 SYSCALL(fork)