There are cases that the operands of an expression are all with rank less
than UINT64/INT64 and the result of the expression is explicitly cast to
UINT64/INT64 to fit the target size.
An example will be:
UINT32 a,b;
// a and b can be any unsigned int type with rank less than UINT64, like
// UINT8, UINT16, etc.
UINT64 c;
c = (UINT64) (a + b);
Some static code checkers may warn that the expression result might
overflow within the rank of "int" (integer promotions) and the result is
then cast to a bigger size.
The commit refines codes by the following rules:
1). When the expression is possible to overflow the range of unsigned int/
int:
c = (UINT64)a + b;
2). When the expression will not overflow within the rank of "int", remove
the explicit type casts:
c = a + b;
3). When the expression will be cast to pointer of possible greater size:
UINT32 a,b;
VOID *c;
c = (VOID *)(UINTN)(a + b); --> c = (VOID *)((UINTN)a + b);
4). When one side of a comparison expression contains only operands with
rank less than UINT32:
UINT8 a;
UINT16 b;
UINTN c;
if ((UINTN)(a + b) > c) {...} --> if (((UINT32)a + b) > c) {...}
For rule 4), if we remove the 'UINTN' type cast like:
if (a + b > c) {...}
The VS compiler will complain with warning C4018 (signed/unsigned
mismatch, level 3 warning) due to promoting 'a + b' to type 'int'.
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
		
	
		
			
				
	
	
		
			153 lines
		
	
	
		
			4.8 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
			
		
		
	
	
			153 lines
		
	
	
		
			4.8 KiB
		
	
	
	
		
			C
		
	
	
	
	
	
| /** @file
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| 
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| Copyright (c) 2015 - 2017, Intel Corporation. All rights reserved.<BR>
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| 
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| This program and the accompanying materials
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| are licensed and made available under the terms and conditions
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| of the BSD License which accompanies this distribution.  The
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| full text of the license may be found at
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| http://opensource.org/licenses/bsd-license.php
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| 
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| THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
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| WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
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| 
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| **/
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| 
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| #include <Uefi.h>
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| #include <Library/BaseLib.h>
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| #include <Library/UefiDriverEntryPoint.h>
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| #include <Library/BaseMemoryLib.h>
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| #include <Library/DebugLib.h>
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| #include <Library/PeCoffLib.h>
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| #include <Library/UefiBootServicesTableLib.h>
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| #include <Library/DxeServicesLib.h>
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| #include <Library/CacheMaintenanceLib.h>
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| #include <Library/UefiLib.h>
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| 
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| /**
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|   Relocate this image under 4G memory.
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| 
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|   @param  ImageHandle  Handle of driver image.
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|   @param  SystemTable  Pointer to system table.
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| 
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|   @retval EFI_SUCCESS  Image successfully relocated.
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|   @retval EFI_ABORTED  Failed to relocate image.
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| 
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| **/
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| EFI_STATUS
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| RelocateImageUnder4GIfNeeded (
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|   IN EFI_HANDLE           ImageHandle,
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|   IN EFI_SYSTEM_TABLE     *SystemTable
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|   )
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| {
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|   EFI_STATUS                                    Status;
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|   UINT8                                         *Buffer;
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|   UINTN                                         BufferSize;
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|   EFI_HANDLE                                    NewImageHandle;
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|   UINTN                                         Pages;
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|   EFI_PHYSICAL_ADDRESS                          FfsBuffer;
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|   PE_COFF_LOADER_IMAGE_CONTEXT                  ImageContext;
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|   VOID                                          *Interface;
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| 
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|   //
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|   // If it is already <4G, no need do relocate
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|   //
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|   if ((UINTN)RelocateImageUnder4GIfNeeded < 0xFFFFFFFF) {
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|     return EFI_SUCCESS;
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|   }
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| 
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|   //
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|   // If locate gEfiCallerIdGuid success, it means 2nd entry.
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|   //
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|   Status = gBS->LocateProtocol (&gEfiCallerIdGuid, NULL, &Interface);
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|   if (!EFI_ERROR (Status)) {
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|     DEBUG ((EFI_D_INFO, "FspNotifyDxe - 2nd entry\n"));
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|     return EFI_SUCCESS;
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|   }
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| 
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|   DEBUG ((EFI_D_INFO, "FspNotifyDxe - 1st entry\n"));
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| 
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|   //
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|   // Here we install a dummy handle
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|   //
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|   NewImageHandle = NULL;
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|   Status = gBS->InstallProtocolInterface (
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|                   &NewImageHandle,
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|                   &gEfiCallerIdGuid,
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|                   EFI_NATIVE_INTERFACE,
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|                   NULL
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|                   );
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|   ASSERT_EFI_ERROR (Status);
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| 
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|   //
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|   // Reload image itself to <4G mem
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|   //
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|   Status = GetSectionFromAnyFv  (
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|              &gEfiCallerIdGuid,
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|              EFI_SECTION_PE32,
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|              0,
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|              (VOID **) &Buffer,
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|              &BufferSize
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|              );
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|   ASSERT_EFI_ERROR (Status);
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|   ImageContext.Handle    = Buffer;
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|   ImageContext.ImageRead = PeCoffLoaderImageReadFromMemory;
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|   //
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|   // Get information about the image being loaded
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|   //
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|   Status = PeCoffLoaderGetImageInfo (&ImageContext);
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|   ASSERT_EFI_ERROR (Status);
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|   if (ImageContext.SectionAlignment > EFI_PAGE_SIZE) {
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|     Pages = EFI_SIZE_TO_PAGES ((UINTN) (ImageContext.ImageSize + ImageContext.SectionAlignment));
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|   } else {
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|     Pages = EFI_SIZE_TO_PAGES ((UINTN) ImageContext.ImageSize);
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|   }
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|   FfsBuffer = 0xFFFFFFFF;
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|   Status = gBS->AllocatePages (
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|                   AllocateMaxAddress,
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|                   EfiBootServicesCode,
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|                   Pages,
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|                   &FfsBuffer
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|                   );
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|   ASSERT_EFI_ERROR (Status);
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|   ImageContext.ImageAddress = (PHYSICAL_ADDRESS)(UINTN)FfsBuffer;
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|   //
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|   // Align buffer on section boundary
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|   //
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|   ImageContext.ImageAddress += ImageContext.SectionAlignment - 1;
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|   ImageContext.ImageAddress &= ~((EFI_PHYSICAL_ADDRESS)ImageContext.SectionAlignment - 1);
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|   //
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|   // Load the image to our new buffer
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|   //
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|   Status = PeCoffLoaderLoadImage (&ImageContext);
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|   ASSERT_EFI_ERROR (Status);
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| 
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|   //
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|   // Relocate the image in our new buffer
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|   //
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|   Status = PeCoffLoaderRelocateImage (&ImageContext);
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|   ASSERT_EFI_ERROR (Status);
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| 
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|   //
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|   // Free the buffer allocated by ReadSection since the image has been relocated in the new buffer
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|   //
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|   gBS->FreePool (Buffer);
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| 
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|   //
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|   // Flush the instruction cache so the image data is written before we execute it
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|   //
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|   InvalidateInstructionCacheRange ((VOID *)(UINTN)ImageContext.ImageAddress, (UINTN)ImageContext.ImageSize);
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| 
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|   DEBUG ((EFI_D_INFO, "Loading driver at 0x%08x EntryPoint=0x%08x\n", (UINTN)ImageContext.ImageAddress, (UINTN)ImageContext.EntryPoint));
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|   Status = ((EFI_IMAGE_ENTRY_POINT)(UINTN)(ImageContext.EntryPoint)) (NewImageHandle, gST);
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|   if (EFI_ERROR (Status)) {
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|     DEBUG ((EFI_D_ERROR, "Error: Image at 0x%08x start failed: %r\n", ImageContext.ImageAddress, Status));
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|     gBS->FreePages (FfsBuffer, Pages);
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|   }
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| 
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|   //
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|   // return error to unload >4G copy, if we already relocate itself to <4G.
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|   //
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|   return EFI_ALREADY_STARTED;
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| }
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