linux-kernel - [PATCH] x86/boot: allow a relocatable kernel to be linked with lld

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Message-Id: <20200501084215.242-1-dima@golovin.in>
Date:   Fri,  1 May 2020 08:42:13 +0000
From:   Dmitry Golovin <dima@...ovin.in>
To:     clang-built-linux@...glegroups.com
Cc:     Dmitry Golovin <dima@...ovin.in>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Daniel Kiper <daniel.kiper@...cle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86/boot: allow a relocatable kernel to be linked with lld

LLD by default disallows relocations in read-only segments. For a
relocatable kernel, we pass -z notext to the linker to explicitly
allow relocations. This behavior is the default for BFD.

Link: https://github.com/ClangBuiltLinux/linux/issues/579
Signed-off-by: Dmitry Golovin <dima@...ovin.in>
---
 arch/x86/boot/compressed/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 5f7c262bcc99..7214751e1671 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -57,6 +57,9 @@ else
 KBUILD_LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
 	&& echo "-z noreloc-overflow -pie --no-dynamic-linker")
 endif
+ifeq ($(CONFIG_RELOCATABLE), y)
+KBUILD_LDFLAGS += -z notext
+endif
 LDFLAGS_vmlinux := -T
 
 hostprogs	:= mkpiggy
-- 
2.25.1