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Date: Thu, 12 Nov 2020 11:38:40 -0700 From: Nathan Chancellor <natechancellor@...il.com> To: Masahiro Yamada <masahiroy@...nel.org>, Michal Marek <michal.lkml@...kovi.net>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Russell King <linux@...linux.org.uk> Cc: Florian Fainelli <f.fainelli@...il.com>, Arnd Bergmann <arnd@...db.de>, Abbott Liu <liuwenliang@...wei.com>, Linus Walleij <linus.walleij@...aro.org>, Jian Cai <jiancai@...gle.com>, Andrey Ryabinin <aryabinin@...tuozzo.com>, Mike Rapoport <rppt@...ux.ibm.com>, Ard Biesheuvel <ardb@...nel.org>, linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, Nathan Chancellor <natechancellor@...il.com>, Nick Desaulniers <ndesaulniers@...gle.com> Subject: [PATCH] kbuild: Always link with '-z norelro' Commit 3bbd3db86470 ("arm64: relocatable: fix inconsistencies in linker script and options") added '-z norelro' to the arm64 Makefile when CONFIG_RELOCATABLE was set to help support ld.lld because ld.lld defaults to '-z relro' but the kernel does not use program headers or adhere to the section layout that is required for RELRO to work. Commit 3b92fa7485eb ("arm64: link with -z norelro regardless of CONFIG_RELOCATABLE") unconditionally added it to LDFLAGS_vmlinux because an error occurs with CONFIG_KASAN set even when CONFIG_RELOCATABLE is unset. As it turns out, ARM experiences the same error after CONFIG_KASAN was implemented, meaning that '-z norelro' needs to be added to that Makefile as well (multi_v7_defconfig + CONFIG_KASAN=y + LD=ld.lld): $ make ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 zImage ld.lld: error: section: .exit.data is not contiguous with other relro sections To avoid playing whack-a-mole with different architectures over time, hoist '-z norelro' into the main Makefile. This does not affect ld.bfd because '-z norelro' is the default for it. Link: https://github.com/ClangBuiltLinux/linux/issues/1189 Suggested-by: Nick Desaulniers <ndesaulniers@...gle.com> Signed-off-by: Nathan Chancellor <natechancellor@...il.com> --- Hi all, This should probably go into Russell's tree with acks from the arm64 and kbuild maintainers. Cheers, Nathan Makefile | 2 ++ arch/arm64/Makefile | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 008aba5f1a20..648bfb486244 100644 --- a/Makefile +++ b/Makefile @@ -984,6 +984,8 @@ ifeq ($(CONFIG_RELR),y) LDFLAGS_vmlinux += --pack-dyn-relocs=relr endif +LDFLAGS_vmlinux += -z norelro + # Align the bit size of userspace programs with the kernel KBUILD_USERCFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS)) KBUILD_USERLDFLAGS += $(filter -m32 -m64 --target=%, $(KBUILD_CFLAGS)) diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 5789c2d18d43..85495ff8f0fd 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -10,7 +10,7 @@ # # Copyright (C) 1995-2001 by Russell King -LDFLAGS_vmlinux :=--no-undefined -X -z norelro +LDFLAGS_vmlinux :=--no-undefined -X ifeq ($(CONFIG_RELOCATABLE), y) # Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour base-commit: f8394f232b1eab649ce2df5c5f15b0e528c92091 -- 2.29.2
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