On Mon, 27 Mar 2023 at 15:10, Leif Lindholm <quic_llind...@quicinc.com> wrote: > > On Mon, Mar 27, 2023 at 13:01:06 +0200, Ard Biesheuvel wrote: > > The ELF based toolchains use objcopy to create HII object files, which > > contain only a single .hii section. This means no GNU note is inserted > > that describes the object as compatible with BTI, even though the lack > > of executable code in such an object makes the distinction irrelevant. > > However, the linker will not add the note globally to the resulting ELF > > executable, and this breaks BTI compatibility. > > > > So let's insert a GNU BTI-compatible ELF note by hand when generating > > such object files. > > > > Signed-off-by: Ard Biesheuvel <a...@kernel.org> > > --- > > ArmPkg/Library/GnuNoteBti.bin | Bin 0 -> 32 bytes > > BaseTools/Conf/tools_def.template | 4 ++-- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/ArmPkg/Library/GnuNoteBti.bin b/ArmPkg/Library/GnuNoteBti.bin > > new file mode 100644 > > index > > 0000000000000000000000000000000000000000..339567b4e89943c610b44767ddad5f631229ed3b > > GIT binary patch > > literal 32 > > dcmZQ!U|<jcVpbq__X`D*3<p?%1S5zA1OOf&0m%RW > > > > literal 0 > > HcmV?d00001 > > > > diff --git a/BaseTools/Conf/tools_def.template > > b/BaseTools/Conf/tools_def.template > > index 471eb67c0c839730..ed6050aa96157cb9 100755 > > --- a/BaseTools/Conf/tools_def.template > > +++ b/BaseTools/Conf/tools_def.template > > @@ -2400,7 +2400,7 @@ RELEASE_GCC5_ARM_DLINK_FLAGS = > > DEF(GCC5_ARM_DLINK_FLAGS) -flto -Os -L$(WORKS > > *_GCC5_AARCH64_DTCPP_FLAGS = DEF(GCC_DTCPP_FLAGS) > > *_GCC5_AARCH64_PLATFORM_FLAGS = > > *_GCC5_AARCH64_PP_FLAGS = $(PLATFORM_FLAGS) DEF(GCC_PP_FLAGS) > > -*_GCC5_AARCH64_RC_FLAGS = DEF(GCC_AARCH64_RC_FLAGS) > > +*_GCC5_AARCH64_RC_FLAGS = DEF(GCC_AARCH64_RC_FLAGS) --add-section > > .note.gnu.property=$(WORKSPACE)/ArmPkg/Library/GnuNoteBti.bin > > --set-section-flags .note.gnu.property=alloc,readonly > > *_GCC5_AARCH64_VFRPP_FLAGS = $(PLATFORM_FLAGS) DEF(GCC_VFRPP_FLAGS) > > *_GCC5_AARCH64_CC_XIPFLAGS = DEF(GCC5_AARCH64_CC_XIPFLAGS) > > > > @@ -2735,7 +2735,7 @@ DEFINE CLANG38_AARCH64_DLINK_FLAGS = > > DEF(CLANG38_AARCH64_TARGET) DEF(GCC_AARCH6 > > *_CLANG38_AARCH64_DLINK2_FLAGS = DEF(GCC_DLINK2_FLAGS_COMMON) > > -Wl,--defsym=PECOFF_HEADER_SIZE=0x228 > > *_CLANG38_AARCH64_PLATFORM_FLAGS = > > *_CLANG38_AARCH64_PP_FLAGS = DEF(GCC_PP_FLAGS) > > DEF(CLANG38_AARCH64_TARGET) $(PLATFORM_FLAGS) > > -*_CLANG38_AARCH64_RC_FLAGS = DEF(GCC_AARCH64_RC_FLAGS) > > +*_CLANG38_AARCH64_RC_FLAGS = DEF(GCC_AARCH64_RC_FLAGS) --add-section > > .note.gnu.property=$(WORKSPACE)/ArmPkg/Library/GnuNoteBti.bin > > --set-section-flags .note.gnu.property=alloc,readonly > > Bikeshedding, but could we have an AARCH64_BTI_RC_FLAGS or something > set, which is expanded for each toolchain profile? I think this is > esoteric enough that it's helpful to group just the > bti-note-incantations together in a single place. >
Sure. It's a bit disappointing that we even need this - the linker should be able to infer that for objects without any executable sections, whether the note exists or not is irrelevant. -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#101954): https://edk2.groups.io/g/devel/message/101954 Mute This Topic: https://groups.io/mt/97879294/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
