mirror of https://github.com/acidanthera/audk.git
MdeModulePkg/FileExplorerLib: avoid packed struct for program data
Struct packing is only necessary for data structures whose in-memory representation is covered by the PI or UEFI specs, and may deviate from the ordinary C rules for alignment. So in case of FileExplorerLib, this applies to the device path struct only, and other structures used to carry program data should not be packed, or we may end up with alignment faults on architectures such as ARM, which don't permit load/store double or multiple instructions to access memory locations that are not 32-bit aligned. E.g., the following call in FileExplorerLibConstructor() InitializeListHead (&gFileExplorerPrivate.FsOptionMenu->Head); which is emitted as follows for 32-bit ARM/Thumb2 by Clang-5.0 3de0: b510 push {r4, lr} 3de2: 4604 mov r4, r0 ... 3de8: e9c4 4400 strd r4, r4, [r4] 3dec: bd10 pop {r4, pc} will perform a double-word store on the first argument, passed in register r0, assuming that the pointer type of the argument is enough to guarantee that the value is suitably aligned. Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Hao Wu <hao.a.wu@intel.com>
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@ -51,6 +51,8 @@ typedef struct {
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EFI_DEVICE_PATH_PROTOCOL End;
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} HII_VENDOR_DEVICE_PATH;
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#pragma pack()
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typedef struct {
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EFI_HANDLE DeviceHandle;
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EFI_DEVICE_PATH_PROTOCOL *DevicePath;
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@ -100,8 +102,6 @@ typedef struct {
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#define FILE_EXPLORER_PRIVATE_FROM_THIS(a) CR (a, FILE_EXPLORER_CALLBACK_DATA, FeConfigAccess, FILE_EXPLORER_CALLBACK_DATA_SIGNATURE)
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#pragma pack()
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extern UINT8 FileExplorerVfrBin[];
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#define MENU_OPTION_SIGNATURE SIGNATURE_32 ('m', 'e', 'n', 'u')
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