Encode arg cageid translation flag

Author: stupendoussuperpowers

src/glibc/lind_syscall/addr_translation.h

@@ -60,6 +60,15 @@ extern "C"
 #define TRANSLATE_UADDR_TO_HOST(uaddr, cageid)                                \
   __lind_translate_uaddr_to_host ((uaddr), (cageid))
 
+// Per-argument translation signaling for threei calls.
+#define LIND_ARG_TRANSLATE_FLAG (1ULL << 63)
+#define LIND_ARG_CAGEID_MASK (~LIND_ARG_TRANSLATE_FLAG)
+#define LIND_ARG_SHOULD_TRANSLATE(arg_cageid)                                 \
+  (((arg_cageid) & LIND_ARG_TRANSLATE_FLAG) != 0)
+#define LIND_ARG_CAGEID_STRIP(arg_cageid) ((arg_cageid) & LIND_ARG_CAGEID_MASK)
+#define LIND_ARG_CAGEID_TRANSLATE(cageid)                                     \
+  ((uint64_t)(cageid) | LIND_ARG_TRANSLATE_FLAG)
+
 /* Translate an array of guest iovec structures to host layout.
    Each iov_base is a wasm32 guest pointer; we split the translated
    64-bit host address across iov_base (low32) and __padding1 (high32).

src/glibc/lind_syscall/lind_syscall.c

@@ -77,6 +77,32 @@ int make_threei_call (unsigned int callnumber,
     uint64_t arg6, uint64_t arg6cageid,
     int translate_errno)
 {
+    if (LIND_ARG_SHOULD_TRANSLATE(arg1cageid)) {
+        arg1 = TRANSLATE_GUEST_POINTER_TO_HOST((const void *)(uintptr_t)arg1);
+    }
+    if (LIND_ARG_SHOULD_TRANSLATE(arg2cageid)) {
+        arg2 = TRANSLATE_GUEST_POINTER_TO_HOST((const void *)(uintptr_t)arg2);
+    }
+    if (LIND_ARG_SHOULD_TRANSLATE(arg3cageid)) {
+        arg3 = TRANSLATE_GUEST_POINTER_TO_HOST((const void *)(uintptr_t)arg3);
+    }
+    if (LIND_ARG_SHOULD_TRANSLATE(arg4cageid)) {
+        arg4 = TRANSLATE_GUEST_POINTER_TO_HOST((const void *)(uintptr_t)arg4);
+    }
+    if (LIND_ARG_SHOULD_TRANSLATE(arg5cageid)) {
+        arg5 = TRANSLATE_GUEST_POINTER_TO_HOST((const void *)(uintptr_t)arg5);
+    }
+    if (LIND_ARG_SHOULD_TRANSLATE(arg6cageid)) {
+        arg6 = TRANSLATE_GUEST_POINTER_TO_HOST((const void *)(uintptr_t)arg6);
+    }
+
+    arg1cageid = LIND_ARG_CAGEID_STRIP(arg1cageid);
+    arg2cageid = LIND_ARG_CAGEID_STRIP(arg2cageid);
+    arg3cageid = LIND_ARG_CAGEID_STRIP(arg3cageid);
+    arg4cageid = LIND_ARG_CAGEID_STRIP(arg4cageid);
+    arg5cageid = LIND_ARG_CAGEID_STRIP(arg5cageid);
+    arg6cageid = LIND_ARG_CAGEID_STRIP(arg6cageid);
+
     int ret = __lind_make_syscall_trampoline(callnumber, 
         callname, 
         self_cageid, target_cageid,