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[92.145.124.62]) by smtp.gmail.com with ESMTPSA id v15-20020a1cf70f000000b003f8d770e935sm16097220wmh.0.2023.06.21.04.45.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jun 2023 04:45:42 -0700 (PDT) From: Alexandre Ghiti To: Ard Biesheuvel , linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org Cc: Alexandre Ghiti Subject: [RFC PATCH 1/1] libstub: zboot: Use -ffunction-sections + --gc-sections Date: Wed, 21 Jun 2023 13:44:39 +0200 Message-Id: <20230621114439.42851-2-alexghiti@rivosinc.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230621114439.42851-1-alexghiti@rivosinc.com> References: <20230621114439.42851-1-alexghiti@rivosinc.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Static linking is done at an object file (actually section) granularity, meaning that if a function in an object has an undefined reference, the link will fail, even though this function is not used in the resulting ELF. To avoid such failures, allow the linker to garbage collect unused sections (which actually are functions). Signed-off-by: Alexandre Ghiti --- drivers/firmware/efi/libstub/Makefile | 1 + drivers/firmware/efi/libstub/Makefile.zboot | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index 3abb2b357482..6182366d00c0 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -40,6 +40,7 @@ KBUILD_CFLAGS := $(subst $(CC_FLAGS_FTRACE),,$(cflags-y)) \ -ffreestanding \ -fno-stack-protector \ $(call cc-option,-fno-addrsig) \ + -ffunction-sections \ -D__DISABLE_EXPORTS # diff --git a/drivers/firmware/efi/libstub/Makefile.zboot b/drivers/firmware/efi/libstub/Makefile.zboot index 89ef820f3b34..5bb52d262133 100644 --- a/drivers/firmware/efi/libstub/Makefile.zboot +++ b/drivers/firmware/efi/libstub/Makefile.zboot @@ -51,7 +51,7 @@ $(obj)/zboot-header.o: $(srctree)/drivers/firmware/efi/libstub/zboot-header.S FO ZBOOT_DEPS := $(obj)/zboot-header.o $(objtree)/drivers/firmware/efi/libstub/lib.a -LDFLAGS_vmlinuz.efi.elf := -T $(srctree)/drivers/firmware/efi/libstub/zboot.lds +LDFLAGS_vmlinuz.efi.elf := -T $(srctree)/drivers/firmware/efi/libstub/zboot.lds --gc-sections $(obj)/vmlinuz.efi.elf: $(obj)/vmlinuz.o $(ZBOOT_DEPS) FORCE $(call if_changed,ld) -- 2.39.2