[PATCH v2 11/17] ArmPkg, BaseTools AARCH64: Add BTI ELF note to .hii objects

["Ard Biesheuvel" <ardb@kernel.org>]

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 <ardb@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
 *_CLANG38_AARCH64_VFRPP_FLAGS    = DEF(GCC_VFRPP_FLAGS) DEF(CLANG38_AARCH64_TARGET) $(PLATFORM_FLAGS)
 *_CLANG38_AARCH64_ASLPP_FLAGS    = DEF(GCC_ASLPP_FLAGS) DEF(CLANG38_AARCH64_TARGET)
 *_CLANG38_AARCH64_CC_XIPFLAGS    = DEF(GCC_AARCH64_CC_XIPFLAGS)
-- 
2.39.2