MdePkg: Create Stack Check Null Libs

Add Null libs for Stack Check and Stack Check Failure Hook Lib that
allow a platform to opt out of stack checks and the stack check failure
hook lib.

StackCheckLib allows implementation (or in this case null implementation)
of stack checks on binaries. There is a Host Application specific version
of this null lib because MSVC host applications must not be linked against
our lib (so the file here is a no-op but that doesn't cause the build
system to fail the build for not building a file for MSVC) as it links
against the MSVC C runtime lib that provides the stack cookie definitions.
GCC host applications do not link against such a C runtime lib and must
be linked against our version.

StackCheckFailureHookLib lets a platform do custom functionality when a
stack check failure occurs (such as log it to a platform defined
mechanism). The null lib simply returns.

Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/MdePkg/Library/StackCheckLibNull/StackCheckLibNullGcc.c b/MdePkg/Library/StackCheckLibNull/StackCheckLibNullGcc.c
new file mode 100644
index 0000000000..cc30632761
--- /dev/null
+++ b/MdePkg/Library/StackCheckLibNull/StackCheckLibNullGcc.c
@@ -0,0 +1,23 @@
+/** @file

+  Defines the stack cookie variable for GCC and Clang compilers.

+

+  Copyright (c) Microsoft Corporation.

+  SPDX-License-Identifier: BSD-2-Clause-Patent

+**/

+

+#include <Uefi.h>

+

+VOID  *__stack_chk_guard = (VOID *)(UINTN)0x0;

+

+/**

+  This function gets called when a gcc/clang generated stack cookie fails. This implementation does nothing when

+  a stack cookie failure occurs.

+

+**/

+VOID

+EFIAPI

+__stack_chk_fail (

+  VOID

+  )

+{

+}