From d6ee6529436a15a0541aff6e1697989ee7dc2c44 Mon Sep 17 00:00:00 2001 From: Fangrui Song Date: Wed, 20 May 2020 11:20:10 -0700 Subject: [PATCH] x86/boot: Discard .discard.unreachable for arch/x86/boot/compressed/vmlinux With commit ce5e3f909fc0 ("efi/printf: Add 64-bit and 8-bit integer support") arch/x86/boot/compressed/vmlinux may have an undesired .discard.unreachable section coming from drivers/firmware/efi/libstub/vsprintf.stub.o. That section gets generated from unreachable() annotations when CONFIG_STACK_VALIDATION is enabled. .discard.unreachable contains an R_X86_64_PC32 relocation which will be warned about by LLD: a non-SHF_ALLOC section (.discard.unreachable) is not part of the memory image, thus conceptually the distance between a non-SHF_ALLOC and a SHF_ALLOC is not a constant which can be resolved at link time: % ld.lld -m elf_x86_64 -T arch/x86/boot/compressed/vmlinux.lds ... -o arch/x86/boot/compressed/vmlinux ld.lld: warning: vsprintf.c:(.discard.unreachable+0x0): has non-ABS relocation R_X86_64_PC32 against symbol '' Reuse the DISCARDS macro which includes .discard.* to drop .discard.unreachable. [ bp: Massage and complete the commit message. ] Reported-by: kbuild test robot Signed-off-by: Fangrui Song Signed-off-by: Borislav Petkov Reviewed-by: Kees Cook Tested-by: Arvind Sankar Tested-by: Sedat Dilek Link: https://lkml.kernel.org/r/20200520182010.242489-1-maskray@google.com --- arch/x86/boot/compressed/vmlinux.lds.S | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S index 508cfa6828c5d..1031af1427760 100644 --- a/arch/x86/boot/compressed/vmlinux.lds.S +++ b/arch/x86/boot/compressed/vmlinux.lds.S @@ -73,4 +73,6 @@ SECTIONS #endif . = ALIGN(PAGE_SIZE); /* keep ZO size page aligned */ _end = .; + + DISCARDS }