The standalone MM core runs in a restricted environment that is set up by a higher privilege level, and which may not allow memory regions to be writable and executable at the same time.
This means that making the StMM core self-relocatable requires that all the targets of the relocation fixups are outside of the executable region of the image, given that we cannot remap the executable code writable from the executable code itself without losing those execute permissions. So instead, use the existing toolchain support to ensure that position independent code is used where possible, and that all the remaining relocated quantities are emitted into the data section. (Note that staticallly initialized const pointers will be emitted into the .data.rel.ro section, which gets pulled into the .data section by our linker script) To ensure that we don't pick up any absolute references in executable code inadvertently (e.g., in assembler code), add the '-z text' linker option which will force the build to fail in this case. Signed-off-by: Ard Biesheuvel <ard.biesheu...@arm.com> --- StandaloneMmPkg/Core/StandaloneMmCore.inf | 4 ++++ StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf | 3 +++ 2 files changed, 7 insertions(+) diff --git a/StandaloneMmPkg/Core/StandaloneMmCore.inf b/StandaloneMmPkg/Core/StandaloneMmCore.inf index d17ff9965bdc..87bf6e9440a7 100644 --- a/StandaloneMmPkg/Core/StandaloneMmCore.inf +++ b/StandaloneMmPkg/Core/StandaloneMmCore.inf @@ -75,3 +75,7 @@ [Guids] gEfiEventLegacyBootGuid gEfiEventExitBootServicesGuid gEfiEventReadyToBootGuid + +[BuildOptions] + GCC:*_*_*_CC_FLAGS = -fpie + GCC:*_*_*_DLINK_FLAGS = -Wl,-z,text,-Bsymbolic,-pie diff --git a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf index 891c292e92f8..7d6ee4e08ecb 100644 --- a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf +++ b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf @@ -48,3 +48,6 @@ [Guids] gEfiMmPeiMmramMemoryReserveGuid gEfiStandaloneMmNonSecureBufferGuid gEfiArmTfCpuDriverEpDescriptorGuid + +[BuildOptions] + GCC:*_*_*_CC_FLAGS = -fpie -- 2.26.2 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#61042): https://edk2.groups.io/g/devel/message/61042 Mute This Topic: https://groups.io/mt/74792291/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
