Re: [edk2-devel] [PATCH v4 1/6] BaseTools/tools_def CLANGDWARF: Permit text relocations
Reviewed-by: Rebecca Cran -- Rebecca Cran On 4/3/23 8:29 AM, Ard Biesheuvel wrote: We rely on PIE executables to get the codegen that is suitable for PE/COFF conversion where the resulting executables can be loaded anywhere in the address space. However, ELF linkers may default to disallowing text relocations in PIE executables, as this would require text segments to be updated at runtime, which is bad for security and increases the copy-on-write footprint of ELF executables and shared libraries. However, none of those concerns apply to PE/COFF executables in the context of EFI, which are copied into memory rather than mmap()'ed, and fixed up by the loader before launch. So pass -z notext to the LLD linker to permit runtime relocations in read-only sections. Signed-off-by: Ard Biesheuvel --- BaseTools/Conf/tools_def.template | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template index ae43101853870c6d..5a3af55bfb09d753 100755 --- a/BaseTools/Conf/tools_def.template +++ b/BaseTools/Conf/tools_def.template @@ -2870,7 +2870,7 @@ DEFINE CLANGDWARF_X64_PREFIX= ENV(CLANG_BIN) DEFINE CLANGDWARF_IA32_X64_DLINK_COMMON = -nostdlib -Wl,-q,--gc-sections -z max-page-size=0x40 DEFINE CLANGDWARF_DLINK2_FLAGS_COMMON = -Wl,--script=$(EDK_TOOLS_PATH)/Scripts/ClangBase.lds DEFINE CLANGDWARF_IA32_X64_ASLDLINK_FLAGS = DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--defsym=PECOFF_HEADER_SIZE=0 DEF(CLANGDWARF_DLINK2_FLAGS_COMMON) -Wl,--entry,ReferenceAcpiTable -u ReferenceAcpiTable -DEFINE CLANGDWARF_IA32_X64_DLINK_FLAGS= DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--entry,$(IMAGE_ENTRY_POINT) -u $(IMAGE_ENTRY_POINT) -Wl,-Map,$(DEST_DIR_DEBUG)/$(BASE_NAME).map,--whole-archive +DEFINE CLANGDWARF_IA32_X64_DLINK_FLAGS= DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--entry,$(IMAGE_ENTRY_POINT) -u $(IMAGE_ENTRY_POINT) -Wl,-Map,$(DEST_DIR_DEBUG)/$(BASE_NAME).map,--whole-archive -Wl,-z,notext DEFINE CLANGDWARF_IA32_DLINK2_FLAGS = -Wl,--defsym=PECOFF_HEADER_SIZE=0x220 DEF(CLANGDWARF_DLINK2_FLAGS_COMMON) DEFINE CLANGDWARF_X64_DLINK2_FLAGS= -Wl,--defsym=PECOFF_HEADER_SIZE=0x228 DEF(CLANGDWARF_DLINK2_FLAGS_COMMON) -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#102559): https://edk2.groups.io/g/devel/message/102559 Mute This Topic: https://groups.io/mt/98036437/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
[edk2-devel] [PATCH v4 1/6] BaseTools/tools_def CLANGDWARF: Permit text relocations
We rely on PIE executables to get the codegen that is suitable for PE/COFF conversion where the resulting executables can be loaded anywhere in the address space. However, ELF linkers may default to disallowing text relocations in PIE executables, as this would require text segments to be updated at runtime, which is bad for security and increases the copy-on-write footprint of ELF executables and shared libraries. However, none of those concerns apply to PE/COFF executables in the context of EFI, which are copied into memory rather than mmap()'ed, and fixed up by the loader before launch. So pass -z notext to the LLD linker to permit runtime relocations in read-only sections. Signed-off-by: Ard Biesheuvel --- BaseTools/Conf/tools_def.template | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template index ae43101853870c6d..5a3af55bfb09d753 100755 --- a/BaseTools/Conf/tools_def.template +++ b/BaseTools/Conf/tools_def.template @@ -2870,7 +2870,7 @@ DEFINE CLANGDWARF_X64_PREFIX= ENV(CLANG_BIN) DEFINE CLANGDWARF_IA32_X64_DLINK_COMMON = -nostdlib -Wl,-q,--gc-sections -z max-page-size=0x40 DEFINE CLANGDWARF_DLINK2_FLAGS_COMMON = -Wl,--script=$(EDK_TOOLS_PATH)/Scripts/ClangBase.lds DEFINE CLANGDWARF_IA32_X64_ASLDLINK_FLAGS = DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--defsym=PECOFF_HEADER_SIZE=0 DEF(CLANGDWARF_DLINK2_FLAGS_COMMON) -Wl,--entry,ReferenceAcpiTable -u ReferenceAcpiTable -DEFINE CLANGDWARF_IA32_X64_DLINK_FLAGS= DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--entry,$(IMAGE_ENTRY_POINT) -u $(IMAGE_ENTRY_POINT) -Wl,-Map,$(DEST_DIR_DEBUG)/$(BASE_NAME).map,--whole-archive +DEFINE CLANGDWARF_IA32_X64_DLINK_FLAGS= DEF(CLANGDWARF_IA32_X64_DLINK_COMMON) -Wl,--entry,$(IMAGE_ENTRY_POINT) -u $(IMAGE_ENTRY_POINT) -Wl,-Map,$(DEST_DIR_DEBUG)/$(BASE_NAME).map,--whole-archive -Wl,-z,notext DEFINE CLANGDWARF_IA32_DLINK2_FLAGS = -Wl,--defsym=PECOFF_HEADER_SIZE=0x220 DEF(CLANGDWARF_DLINK2_FLAGS_COMMON) DEFINE CLANGDWARF_X64_DLINK2_FLAGS= -Wl,--defsym=PECOFF_HEADER_SIZE=0x228 DEF(CLANGDWARF_DLINK2_FLAGS_COMMON) -- 2.39.2 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#102406): https://edk2.groups.io/g/devel/message/102406 Mute This Topic: https://groups.io/mt/98036437/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
