linux-kernel - [PATCH 2/2] kbuild: Disable CONFIG_LD_ORPHAN

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Date:   Fri, 13 Nov 2020 12:55:53 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Masahiro Yamada <masahiroy@...nel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Kees Cook <keescook@...omium.org>
Cc:     Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Nick Desaulniers <ndesaulniers@...gle.com>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        linux-kernel@...r.kernel.org, linux-kbuild@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linuxppc-dev@...ts.ozlabs.org, clang-built-linux@...glegroups.com,
        Nathan Chancellor <natechancellor@...il.com>,
        "kernelci . org bot" <bot@...nelci.org>,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH 2/2] kbuild: Disable CONFIG_LD_ORPHAN_WARN for ld.lld 10.0.1

ld.lld 10.0.1 spews a bunch of various warnings about .rela sections,
along with a few others. Newer versions of ld.lld do not have these
warnings. As a result, do not add '--orphan-handling=warn' to
LDFLAGS_vmlinux if ld.lld's version is not new enough.

Reported-by: Arvind Sankar <nivedita@...m.mit.edu>
Reported-by: kernelci.org bot <bot@...nelci.org>
Reported-by: Mark Brown <broonie@...nel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/1187
Link: https://github.com/ClangBuiltLinux/linux/issues/1193
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 MAINTAINERS            |  1 +
 init/Kconfig           |  6 +++++-
 scripts/lld-version.sh | 20 ++++++++++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100755 scripts/lld-version.sh

diff --git a/MAINTAINERS b/MAINTAINERS
index 3da6d8c154e4..4b83d3591ec7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4284,6 +4284,7 @@ B:	https://github.com/ClangBuiltLinux/linux/issues
 C:	irc://chat.freenode.net/clangbuiltlinux
 F:	Documentation/kbuild/llvm.rst
 F:	scripts/clang-tools/
+F:	scripts/lld-version.sh
 K:	\b(?i:clang|llvm)\b
 
 CLEANCACHE API
diff --git a/init/Kconfig b/init/Kconfig
index a270716562de..40c9ca60ac1d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -47,6 +47,10 @@ config CLANG_VERSION
 	int
 	default $(shell,$(srctree)/scripts/clang-version.sh $(CC))
 
+config LLD_VERSION
+	int
+	default $(shell,$(srctree)/scripts/lld-version.sh $(LD))
+
 config CC_CAN_LINK
 	bool
 	default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag)) if 64BIT
@@ -1349,7 +1353,7 @@ config LD_DEAD_CODE_DATA_ELIMINATION
 	  own risk.
 
 config LD_ORPHAN_WARN
-	def_bool ARCH_WANT_LD_ORPHAN_WARN && $(ld-option,--orphan-handling=warn)
+	def_bool ARCH_WANT_LD_ORPHAN_WARN && $(ld-option,--orphan-handling=warn) && (!LD_IS_LLD || LLD_VERSION >= 110000)
 
 config SYSCTL
 	bool
diff --git a/scripts/lld-version.sh b/scripts/lld-version.sh
new file mode 100755
index 000000000000..cc779f412e39
--- /dev/null
+++ b/scripts/lld-version.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# ld.lld-version ld.lld-command
+#
+# Print the linker version of `ld.lld-command' in a 5 or 6-digit form
+# such as `100001' for ld.lld 10.0.1 etc.
+
+linker="$*"
+
+if ! ( $linker --version | grep -q LLD ); then
+	echo 0
+	exit 1
+fi
+
+VERSION=$($linker --version | cut -d ' ' -f 2)
+MAJOR=$(echo $VERSION | cut -d . -f 1)
+MINOR=$(echo $VERSION | cut -d . -f 2)
+PATCHLEVEL=$(echo $VERSION | cut -d . -f 3)
+printf "%d%02d%02d\\n" $MAJOR $MINOR $PATCHLEVEL
-- 
2.29.2