| Message ID | 20181208102431.9185-1-ard.biesheuvel@linaro.org |
|---|---|
| State | Accepted |
| Commit | 765fb87c2b7085780983df0c1a13e0d2f951b798 |
| Headers | show |
| Series | [edk2] MdeModulePkg/FileExplorerLib: avoid packed struct for program data | expand |
On Sat, Dec 08, 2018 at 11:24:31AM +0100, Ard Biesheuvel wrote: > 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> I agree with the architectural rationale. However, I also decided to have a look. $ git grep "} HII_VENDOR_DEVICE_PATH;" EdkCompatibilityPkg/Compatibility/FrameworkHiiOnUefiHiiThunk/HiiDatabase.h:} HII_VENDOR_DEVICE_PATH; EdkCompatibilityPkg/Foundation/Library/Dxe/UefiEfiIfrSupportLib/UefiIfrLibrary.h:} HII_VENDOR_DEVICE_PATH; EmbeddedPkg/Drivers/ConsolePrefDxe/ConsolePrefDxe.c:} HII_VENDOR_DEVICE_PATH; EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c:} HII_VENDOR_DEVICE_PATH; IntelFrameworkModulePkg/Library/LegacyBootMaintUiLib/LegacyBootMaintUi.h:} HII_VENDOR_DEVICE_PATH; IntelFrameworkModulePkg/Universal/BdsDxe/Bds.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Application/UiApp/Ui.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Library/BootMaintenanceManagerUiLib/BootMaintenanceManager.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Library/BootManagerUiLib/BootManager.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Library/DeviceManagerUiLib/DeviceManager.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Library/FileExplorerLib/FileExplorer.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Library/PlatformVarCleanupLib/PlatVarCleanup.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Universal/DriverSampleDxe/DriverSample.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Universal/HiiResourcesSampleDxe/HiiResourcesSample.c:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Universal/Network/IScsiDxe/IScsiConfig.h:} HII_VENDOR_DEVICE_PATH; MdeModulePkg/Universal/PlatformDriOverrideDxe/PlatDriOverrideDxe.c:} HII_VENDOR_DEVICE_PATH; NetworkPkg/IScsiDxe/IScsiConfig.h:} HII_VENDOR_DEVICE_PATH; NetworkPkg/TlsAuthConfigDxe/TlsAuthConfigImpl.h:} HII_VENDOR_DEVICE_PATH; QuarkPlatformPkg/Platform/Dxe/Setup/SetupPlatform.h:} HII_VENDOR_DEVICE_PATH; SecurityPkg/Tcg/Opal/OpalPassword/OpalHii.h:} HII_VENDOR_DEVICE_PATH; SecurityPkg/Tcg/Tcg2Config/Tcg2ConfigImpl.h:} HII_VENDOR_DEVICE_PATH; SecurityPkg/Tcg/TcgConfigDxe/TcgConfigImpl.h:} HII_VENDOR_DEVICE_PATH; SecurityPkg/UserIdentification/PwdCredentialProviderDxe/PwdCredentialProvider.h:} HII_VENDOR_DEVICE_PATH; SecurityPkg/UserIdentification/UserIdentifyManagerDxe/UserIdentifyManager.h:} HII_VENDOR_DEVICE_PATH; SecurityPkg/UserIdentification/UserProfileManagerDxe/UserProfileManager.h:} HII_VENDOR_DEVICE_PATH; SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigImpl.h:} HII_VENDOR_DEVICE_PATH; Vlv2TbltDevicePkg/Library/PlatformBdsLib/BdsPlatform.h:} HII_VENDOR_DEVICE_PATH; Vlv2TbltDevicePkg/PlatformSetupDxe/PlatformSetupDxe.c:} HII_VENDOR_DEVICE_PATH; Now, I will confess to being lazy and not manually checking all of them, but 100% of the ones I did check were identical (except in packedness). Does this definition belong in a central header somewhere rather than in 29 (and counting) different locations, implemented differently? / Leif > --- > MdeModulePkg/Library/FileExplorerLib/FileExplorer.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > index bf1450dbd581..603185abe4b1 100644 > --- a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > +++ b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > @@ -51,6 +51,8 @@ typedef struct { > EFI_DEVICE_PATH_PROTOCOL End; > } HII_VENDOR_DEVICE_PATH; > > +#pragma pack() > + > typedef struct { > EFI_HANDLE DeviceHandle; > EFI_DEVICE_PATH_PROTOCOL *DevicePath; > @@ -100,8 +102,6 @@ typedef struct { > > #define FILE_EXPLORER_PRIVATE_FROM_THIS(a) CR (a, FILE_EXPLORER_CALLBACK_DATA, FeConfigAccess, FILE_EXPLORER_CALLBACK_DATA_SIGNATURE) > > -#pragma pack() > - > extern UINT8 FileExplorerVfrBin[]; > > #define MENU_OPTION_SIGNATURE SIGNATURE_32 ('m', 'e', 'n', 'u') > -- > 2.19.2 > > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
Ard: I agree this change. Leif: On the duplicated definition of HII_VENDOR_DEVICE_PATH, MdeModulePkg DriverSampleDxe first defines it and use it as the driver level definition. Other UEFI HII driver may refer to the driver sample driver and define the same structure. One centralized header file can be defined for the default HII vendor device path. If the driver wants to use the different one, it can define its own structure. Thanks Liming > -----Original Message----- > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Leif Lindholm > Sent: Monday, December 10, 2018 8:26 PM > To: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Cc: Wu, Hao A <hao.a.wu@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>; edk2-devel@lists.01.org > Subject: Re: [edk2] [PATCH] MdeModulePkg/FileExplorerLib: avoid packed struct for program data > > On Sat, Dec 08, 2018 at 11:24:31AM +0100, Ard Biesheuvel wrote: > > 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> > > I agree with the architectural rationale. > > However, I also decided to have a look. > > $ git grep "} HII_VENDOR_DEVICE_PATH;" > EdkCompatibilityPkg/Compatibility/FrameworkHiiOnUefiHiiThunk/HiiDatabase.h:} HII_VENDOR_DEVICE_PATH; > EdkCompatibilityPkg/Foundation/Library/Dxe/UefiEfiIfrSupportLib/UefiIfrLibrary.h:} HII_VENDOR_DEVICE_PATH; > EmbeddedPkg/Drivers/ConsolePrefDxe/ConsolePrefDxe.c:} HII_VENDOR_DEVICE_PATH; > EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c:} HII_VENDOR_DEVICE_PATH; > IntelFrameworkModulePkg/Library/LegacyBootMaintUiLib/LegacyBootMaintUi.h:} HII_VENDOR_DEVICE_PATH; > IntelFrameworkModulePkg/Universal/BdsDxe/Bds.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Application/UiApp/Ui.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Library/BootMaintenanceManagerUiLib/BootMaintenanceManager.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Library/BootManagerUiLib/BootManager.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Library/DeviceManagerUiLib/DeviceManager.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Library/FileExplorerLib/FileExplorer.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Library/PlatformVarCleanupLib/PlatVarCleanup.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Universal/DriverSampleDxe/DriverSample.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Universal/HiiResourcesSampleDxe/HiiResourcesSample.c:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Universal/Network/IScsiDxe/IScsiConfig.h:} HII_VENDOR_DEVICE_PATH; > MdeModulePkg/Universal/PlatformDriOverrideDxe/PlatDriOverrideDxe.c:} HII_VENDOR_DEVICE_PATH; > NetworkPkg/IScsiDxe/IScsiConfig.h:} HII_VENDOR_DEVICE_PATH; > NetworkPkg/TlsAuthConfigDxe/TlsAuthConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > QuarkPlatformPkg/Platform/Dxe/Setup/SetupPlatform.h:} HII_VENDOR_DEVICE_PATH; > SecurityPkg/Tcg/Opal/OpalPassword/OpalHii.h:} HII_VENDOR_DEVICE_PATH; > SecurityPkg/Tcg/Tcg2Config/Tcg2ConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > SecurityPkg/Tcg/TcgConfigDxe/TcgConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > SecurityPkg/UserIdentification/PwdCredentialProviderDxe/PwdCredentialProvider.h:} HII_VENDOR_DEVICE_PATH; > SecurityPkg/UserIdentification/UserIdentifyManagerDxe/UserIdentifyManager.h:} HII_VENDOR_DEVICE_PATH; > SecurityPkg/UserIdentification/UserProfileManagerDxe/UserProfileManager.h:} HII_VENDOR_DEVICE_PATH; > SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > Vlv2TbltDevicePkg/Library/PlatformBdsLib/BdsPlatform.h:} HII_VENDOR_DEVICE_PATH; > Vlv2TbltDevicePkg/PlatformSetupDxe/PlatformSetupDxe.c:} HII_VENDOR_DEVICE_PATH; > > Now, I will confess to being lazy and not manually checking all of > them, but 100% of the ones I did check were identical (except in > packedness). > > Does this definition belong in a central header somewhere rather than > in 29 (and counting) different locations, implemented differently? > > / > Leif > > > --- > > MdeModulePkg/Library/FileExplorerLib/FileExplorer.h | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > index bf1450dbd581..603185abe4b1 100644 > > --- a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > +++ b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > @@ -51,6 +51,8 @@ typedef struct { > > EFI_DEVICE_PATH_PROTOCOL End; > > } HII_VENDOR_DEVICE_PATH; > > > > +#pragma pack() > > + > > typedef struct { > > EFI_HANDLE DeviceHandle; > > EFI_DEVICE_PATH_PROTOCOL *DevicePath; > > @@ -100,8 +102,6 @@ typedef struct { > > > > #define FILE_EXPLORER_PRIVATE_FROM_THIS(a) CR (a, FILE_EXPLORER_CALLBACK_DATA, FeConfigAccess, > FILE_EXPLORER_CALLBACK_DATA_SIGNATURE) > > > > -#pragma pack() > > - > > extern UINT8 FileExplorerVfrBin[]; > > > > #define MENU_OPTION_SIGNATURE SIGNATURE_32 ('m', 'e', 'n', 'u') > > -- > > 2.19.2 > > > > _______________________________________________ > > edk2-devel mailing list > > edk2-devel@lists.01.org > > https://lists.01.org/mailman/listinfo/edk2-devel > _______________________________________________ > edk2-devel mailing list > edk2-devel@lists.01.org > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On Mon, Dec 10, 2018 at 02:39:01PM +0000, Gao, Liming wrote: > Ard: > I agree this change. > > Leif: > On the duplicated definition of HII_VENDOR_DEVICE_PATH, > MdeModulePkg DriverSampleDxe first defines it and use it as the > driver level definition. Other UEFI HII driver may refer to the > driver sample driver and define the same structure. One > centralized header file can be defined for the default HII vendor > device path. If the driver wants to use the different one, it can > define its own structure. Exactly. You're correct, my comment was imprecise. But the fact that 29 locations use the same default HII vendor device patch definition suggests that there would be value in having a centralised default to refer to. I raised https://bugzilla.tianocore.org/show_bug.cgi?id=1388 Actually, I found there are 3 more in edk2-platforms :) https://bugzilla.tianocore.org/show_bug.cgi?id=1389 Regards, Leif > > Thanks > Liming > > -----Original Message----- > > From: edk2-devel [mailto:edk2-devel-bounces@lists.01.org] On Behalf Of Leif Lindholm > > Sent: Monday, December 10, 2018 8:26 PM > > To: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > Cc: Wu, Hao A <hao.a.wu@intel.com>; Ni, Ruiyu <ruiyu.ni@intel.com>; edk2-devel@lists.01.org > > Subject: Re: [edk2] [PATCH] MdeModulePkg/FileExplorerLib: avoid packed struct for program data > > > > On Sat, Dec 08, 2018 at 11:24:31AM +0100, Ard Biesheuvel wrote: > > > 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> > > > > I agree with the architectural rationale. > > > > However, I also decided to have a look. > > > > $ git grep "} HII_VENDOR_DEVICE_PATH;" > > EdkCompatibilityPkg/Compatibility/FrameworkHiiOnUefiHiiThunk/HiiDatabase.h:} HII_VENDOR_DEVICE_PATH; > > EdkCompatibilityPkg/Foundation/Library/Dxe/UefiEfiIfrSupportLib/UefiIfrLibrary.h:} HII_VENDOR_DEVICE_PATH; > > EmbeddedPkg/Drivers/ConsolePrefDxe/ConsolePrefDxe.c:} HII_VENDOR_DEVICE_PATH; > > EmbeddedPkg/Drivers/DtPlatformDxe/DtPlatformDxe.c:} HII_VENDOR_DEVICE_PATH; > > IntelFrameworkModulePkg/Library/LegacyBootMaintUiLib/LegacyBootMaintUi.h:} HII_VENDOR_DEVICE_PATH; > > IntelFrameworkModulePkg/Universal/BdsDxe/Bds.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Application/UiApp/Ui.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Library/BootMaintenanceManagerUiLib/BootMaintenanceManager.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Library/BootManagerUiLib/BootManager.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Library/DeviceManagerUiLib/DeviceManager.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Library/FileExplorerLib/FileExplorer.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Library/PlatformVarCleanupLib/PlatVarCleanup.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Universal/Disk/RamDiskDxe/RamDiskImpl.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Universal/DriverSampleDxe/DriverSample.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Universal/HiiResourcesSampleDxe/HiiResourcesSample.c:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Universal/Network/IScsiDxe/IScsiConfig.h:} HII_VENDOR_DEVICE_PATH; > > MdeModulePkg/Universal/PlatformDriOverrideDxe/PlatDriOverrideDxe.c:} HII_VENDOR_DEVICE_PATH; > > NetworkPkg/IScsiDxe/IScsiConfig.h:} HII_VENDOR_DEVICE_PATH; > > NetworkPkg/TlsAuthConfigDxe/TlsAuthConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > > QuarkPlatformPkg/Platform/Dxe/Setup/SetupPlatform.h:} HII_VENDOR_DEVICE_PATH; > > SecurityPkg/Tcg/Opal/OpalPassword/OpalHii.h:} HII_VENDOR_DEVICE_PATH; > > SecurityPkg/Tcg/Tcg2Config/Tcg2ConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > > SecurityPkg/Tcg/TcgConfigDxe/TcgConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > > SecurityPkg/UserIdentification/PwdCredentialProviderDxe/PwdCredentialProvider.h:} HII_VENDOR_DEVICE_PATH; > > SecurityPkg/UserIdentification/UserIdentifyManagerDxe/UserIdentifyManager.h:} HII_VENDOR_DEVICE_PATH; > > SecurityPkg/UserIdentification/UserProfileManagerDxe/UserProfileManager.h:} HII_VENDOR_DEVICE_PATH; > > SecurityPkg/VariableAuthenticated/SecureBootConfigDxe/SecureBootConfigImpl.h:} HII_VENDOR_DEVICE_PATH; > > Vlv2TbltDevicePkg/Library/PlatformBdsLib/BdsPlatform.h:} HII_VENDOR_DEVICE_PATH; > > Vlv2TbltDevicePkg/PlatformSetupDxe/PlatformSetupDxe.c:} HII_VENDOR_DEVICE_PATH; > > > > Now, I will confess to being lazy and not manually checking all of > > them, but 100% of the ones I did check were identical (except in > > packedness). > > > > Does this definition belong in a central header somewhere rather than > > in 29 (and counting) different locations, implemented differently? > > > > / > > Leif > > > > > --- > > > MdeModulePkg/Library/FileExplorerLib/FileExplorer.h | 4 ++-- > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > > index bf1450dbd581..603185abe4b1 100644 > > > --- a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > > +++ b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > > @@ -51,6 +51,8 @@ typedef struct { > > > EFI_DEVICE_PATH_PROTOCOL End; > > > } HII_VENDOR_DEVICE_PATH; > > > > > > +#pragma pack() > > > + > > > typedef struct { > > > EFI_HANDLE DeviceHandle; > > > EFI_DEVICE_PATH_PROTOCOL *DevicePath; > > > @@ -100,8 +102,6 @@ typedef struct { > > > > > > #define FILE_EXPLORER_PRIVATE_FROM_THIS(a) CR (a, FILE_EXPLORER_CALLBACK_DATA, FeConfigAccess, > > FILE_EXPLORER_CALLBACK_DATA_SIGNATURE) > > > > > > -#pragma pack() > > > - > > > extern UINT8 FileExplorerVfrBin[]; > > > > > > #define MENU_OPTION_SIGNATURE SIGNATURE_32 ('m', 'e', 'n', 'u') > > > -- > > > 2.19.2 > > > > > > _______________________________________________ > > > edk2-devel mailing list > > > edk2-devel@lists.01.org > > > https://lists.01.org/mailman/listinfo/edk2-devel > > _______________________________________________ > > edk2-devel mailing list > > edk2-devel@lists.01.org > > https://lists.01.org/mailman/listinfo/edk2-devel _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
> -----Original Message----- > From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org] > Sent: Saturday, December 08, 2018 6:25 PM > To: edk2-devel@lists.01.org > Cc: Wang, Jian J; Wu, Hao A; Ni, Ruiyu; Ard Biesheuvel > Subject: [PATCH] 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> > --- > MdeModulePkg/Library/FileExplorerLib/FileExplorer.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > index bf1450dbd581..603185abe4b1 100644 > --- a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > +++ b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > @@ -51,6 +51,8 @@ typedef struct { > EFI_DEVICE_PATH_PROTOCOL End; > } HII_VENDOR_DEVICE_PATH; > > +#pragma pack() > + > typedef struct { > EFI_HANDLE DeviceHandle; > EFI_DEVICE_PATH_PROTOCOL *DevicePath; > @@ -100,8 +102,6 @@ typedef struct { > > #define FILE_EXPLORER_PRIVATE_FROM_THIS(a) CR (a, > FILE_EXPLORER_CALLBACK_DATA, FeConfigAccess, > FILE_EXPLORER_CALLBACK_DATA_SIGNATURE) > > -#pragma pack() > - Reviewed-by: Hao Wu <hao.a.wu@intel.com> Best Regards, Hao Wu > extern UINT8 FileExplorerVfrBin[]; > > #define MENU_OPTION_SIGNATURE SIGNATURE_32 ('m', 'e', 'n', 'u') > -- > 2.19.2 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
On Tue, 11 Dec 2018 at 02:48, Wu, Hao A <hao.a.wu@intel.com> wrote: > > > -----Original Message----- > > From: Ard Biesheuvel [mailto:ard.biesheuvel@linaro.org] > > Sent: Saturday, December 08, 2018 6:25 PM > > To: edk2-devel@lists.01.org > > Cc: Wang, Jian J; Wu, Hao A; Ni, Ruiyu; Ard Biesheuvel > > Subject: [PATCH] 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> > > --- > > MdeModulePkg/Library/FileExplorerLib/FileExplorer.h | 4 ++-- > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > index bf1450dbd581..603185abe4b1 100644 > > --- a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > +++ b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h > > @@ -51,6 +51,8 @@ typedef struct { > > EFI_DEVICE_PATH_PROTOCOL End; > > } HII_VENDOR_DEVICE_PATH; > > > > +#pragma pack() > > + > > typedef struct { > > EFI_HANDLE DeviceHandle; > > EFI_DEVICE_PATH_PROTOCOL *DevicePath; > > @@ -100,8 +102,6 @@ typedef struct { > > > > #define FILE_EXPLORER_PRIVATE_FROM_THIS(a) CR (a, > > FILE_EXPLORER_CALLBACK_DATA, FeConfigAccess, > > FILE_EXPLORER_CALLBACK_DATA_SIGNATURE) > > > > -#pragma pack() > > - > > Reviewed-by: Hao Wu <hao.a.wu@intel.com> > > Best Regards, > Hao Wu > Thanks all Pushed as f0574a194c1e..765fb87c2b70 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel
diff --git a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h index bf1450dbd581..603185abe4b1 100644 --- a/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h +++ b/MdeModulePkg/Library/FileExplorerLib/FileExplorer.h @@ -51,6 +51,8 @@ typedef struct { EFI_DEVICE_PATH_PROTOCOL End; } HII_VENDOR_DEVICE_PATH; +#pragma pack() + typedef struct { EFI_HANDLE DeviceHandle; EFI_DEVICE_PATH_PROTOCOL *DevicePath; @@ -100,8 +102,6 @@ typedef struct { #define FILE_EXPLORER_PRIVATE_FROM_THIS(a) CR (a, FILE_EXPLORER_CALLBACK_DATA, FeConfigAccess, FILE_EXPLORER_CALLBACK_DATA_SIGNATURE) -#pragma pack() - extern UINT8 FileExplorerVfrBin[]; #define MENU_OPTION_SIGNATURE SIGNATURE_32 ('m', 'e', 'n', 'u')
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> --- MdeModulePkg/Library/FileExplorerLib/FileExplorer.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- 2.19.2 _______________________________________________ edk2-devel mailing list edk2-devel@lists.01.org https://lists.01.org/mailman/listinfo/edk2-devel