Fix Win32 Unknown Device function handling

The handling of unknown device functions queried with vkGetInstanceProcAddr
required an additional pointer dereference to get the dispatch table.

The VkDevice handle is a pointer to the `chain_device` member of
`loader_device`. This member is actually a pointer to `loader_dispatch`, or
put another way, the "start" of `loader_device`. Thus, to get access to the
dispatch table, we need to dereference the VkDevice passed into the function
then dereference the chain_device to get loader_dispatch`.

diff --git a/loader/unknown_ext_chain_masm.asm b/loader/unknown_ext_chain_masm.asm
index 52441fa..f1323bd 100644 (file)
--- a/loader/unknown_ext_chain_masm.asm
+++ b/loader/unknown_ext_chain_masm.asm
@@ -108,7 +108,8 @@ endm
 DevExtTramp macro num
 public _vkdev_ext&num&@4
 _vkdev_ext&num&@4:
-    mov     eax, dword ptr [esp + 4]                                           ; Dereference the handle to get the dispatch table
+    mov     eax, dword ptr [esp + 4]                                           ; Dereference the handle to get VkDevice chain_device
+    mov     eax, dword ptr [eax]                                               ; Dereference the chain_device to get the loader_dispatch
     jmp     dword ptr [eax + (EXT_OFFSET_DEVICE_DISPATCH + (PTR_SIZE * num))]  ; Jump to the appropriate call chain
 endm