x86_64: Support 8 byte inlined port rights to avoid message resizing.

If a port is inlined in a message, the user has to use
mach_port_name_inlined_t to define each port. Out of line memory
continues to use mach_port_name_t since that memory has to be copied to
the kernel anyway.

Both copyinmsg and copyoutmsg can be reduced to nothing (if we ignore
USER32) as a follow up but kept this patch simple for ease of review.

1 files changed, 18 insertions, 0 deletions

diff --git a/include/mach/message.h b/include/mach/message.h
index 17d3592f..21e99896 100644
--- a/include/mach/message.h
+++ b/include/mach/message.h
@@ -221,6 +221,24 @@ typedef unsigned int mach_msg_type_name_t;
 typedef unsigned int mach_msg_type_size_t;
 typedef natural_t  mach_msg_type_number_t;
 
+/**
+ * Structure used for inlined port rights in messages.
+ *
+ * We use this to avoid having to perform message resizing in the kernel
+ * since userspace port rights might be smaller than kernel ports in 64 bit
+ * architectures.
+ */
+typedef struct {
+    union {
+        mach_port_name_t name;
+#ifdef KERNEL
+        mach_port_t kernel_port;
+#else
+        uintptr_t kernel_port_do_not_use;
+#endif  /* KERNEL */
+    };
+} mach_port_name_inlined_t;
+
 typedef struct  {
 #ifdef __x86_64__
     /*