Define PRIVATE and add it to all global symbols so we don't export assembly functions.

libvpx/source/libvpx/vpx_ports/x86_abi_support.asm

 ;
 ;  Copyright (c) 2010 The WebM project authors. All Rights Reserved.
 ;
 ;  Use of this source code is governed by a BSD-style license
 ;  that can be found in the LICENSE file in the root of the source
 ;  tree. An additional intellectual property rights grant can be found
 ;  in the file PATENTS.  All contributing project authors may
 ;  be found in the AUTHORS file in the root of the source tree.
 ;
 
@@ skipping 74 matching lines @@
 %ifidn   __OUTPUT_FORMAT__,elf32
 %define sym(x) x
 %elifidn __OUTPUT_FORMAT__,elf64
 %define sym(x) x
 %elifidn __OUTPUT_FORMAT__,x64
 %define sym(x) x
 %else
 %define sym(x) _ %+ x
 %endif
 
+
+; PRIVATE
+; Macro for the attribute to hide a global symbol for the target ABI.
+;
+; Chromium doesn't like exported global symbols due to symbol clashing with
+; plugins among other things.
+;
+; Requires Chromium's patched copy of yasm:
+;   http://src.chromium.org/viewvc/chrome?view=rev&revision=73761
+;   http://www.tortall.net/projects/yasm/ticket/236
+;
+%ifidn   __OUTPUT_FORMAT__,elf32
+%define PRIVATE :hidden
+%elifidn __OUTPUT_FORMAT__,elf64
+%define PRIVATE :hidden
+%elifidn __OUTPUT_FORMAT__,x64
+%define PRIVATE
+%else
+%define PRIVATE :private_extern
+%endif
+
+
 ; arg()
 ; Return the address specification of the given argument
 ;
 %if ABI_IS_32BIT
   %define arg(x) [ebp+8+4*x]
 %else
   ; 64 bit ABI passes arguments in registers. This is a workaround to get up
   ; and running quickly. Relies on SHADOW_ARGS_TO_STACK
   %ifidn __OUTPUT_FORMAT__,x64
     %define arg(x) [rbp+16+8*x]
@@ skipping 187 matching lines @@
 
 ; Tell GNU ld that we don't require an executable stack.
 %ifidn __OUTPUT_FORMAT__,elf32
 section .note.GNU-stack noalloc noexec nowrite progbits
 section .text
 %elifidn __OUTPUT_FORMAT__,elf64
 section .note.GNU-stack noalloc noexec nowrite progbits
 section .text
 %endif