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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Kees Cook <keescook@chromium.org>,
        Borislav Petkov <bp@suse.de>, "H. Peter Anvin" <hpa@zytor.com>,
        Ingo Molnar <mingo@redhat.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        clang-built-linux@googlegroups.com, x86-ml <x86@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.14 135/193] x86/build: Keep local relocations with ld.lld
Date:   Wed, 29 May 2019 20:06:29 -0700
Message-Id: <20190530030507.215882392@linuxfoundation.org>
In-Reply-To: <20190530030446.953835040@linuxfoundation.org>
References: <20190530030446.953835040@linuxfoundation.org>
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[ Upstream commit 7c21383f3429dd70da39c0c7f1efa12377a47ab6 ]

The LLVM linker (ld.lld) defaults to removing local relocations, which
causes KASLR boot failures. ld.bfd and ld.gold already handle this
correctly. This adds the explicit instruction "--discard-none" during
the link phase. There is no change in output for ld.bfd and ld.gold,
but ld.lld now produces an image with all the needed relocations.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: clang-built-linux@googlegroups.com
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190404214027.GA7324@beast
Link: https://github.com/ClangBuiltLinux/linux/issues/404
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index eb1f8f249dc35..b4c72da8a7adb 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -48,7 +48,7 @@ export REALMODE_CFLAGS
 export BITS
 
 ifdef CONFIG_X86_NEED_RELOCS
-        LDFLAGS_vmlinux := --emit-relocs
+        LDFLAGS_vmlinux := --emit-relocs --discard-none
 endif
 
 #
-- 
2.20.1