MdeModulePkg/Core: fix too many available pages between BS_Data

The root cause is an unnecessary check to Size parameter in function
AdjustMemoryS(). It will cause one standalone free page (happen to have
Guard page around) in the free memory list cannot be allocated, even if
the requested memory size is less than a page.

  //
  // At least one more page needed for Guard page.
  //
  if (Size < (SizeRequested + EFI_PAGES_TO_SIZE (1))) {
    return 0;
  }

The following code in the same function actually covers above check
implicitly. So the fix is simply removing above check.

Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
(cherry picked from commit 8b13bca9b81490fc0e42df25d5feb82bbb47833e)

1 files changed, 1 insertions, 8 deletions

diff --git a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
index d7906e08c5..19245049c2 100644
--- a/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
+++ b/MdeModulePkg/Core/Dxe/Mem/HeapGuard.c
@@ -1,7 +1,7 @@
 /** @file

   UEFI Heap Guard functions.

 

-Copyright (c) 2017, Intel Corporation. All rights reserved.<BR>

+Copyright (c) 2017-2018, Intel Corporation. All rights reserved.<BR>

 This program and the accompanying materials

 are licensed and made available under the terms and conditions of the BSD License

 which accompanies this distribution.  The full text of the license may be found at

@@ -905,13 +905,6 @@ AdjustMemoryS (
 

   Target = Start + Size - SizeRequested;

 

-  //

-  // At least one more page needed for Guard page.

-  //

-  if (Size < (SizeRequested + EFI_PAGES_TO_SIZE (1))) {

-    return 0;

-  }

-

   if (!IsGuardPage (Start + Size)) {

     // No Guard at tail to share. One more page is needed.

     Target -= EFI_PAGES_TO_SIZE (1);