[PATCH] kbuild: Disable CONFIG_LD_ORPHAN_WARN for ld.lld 10.0.1

From: Nathan Chancellor
Date: Tue Nov 17 2020 - 22:11:26 EST


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.

Link: https://github.com/ClangBuiltLinux/linux/issues/1187
Link: https://github.com/ClangBuiltLinux/linux/issues/1193
Reported-by: Arvind Sankar <nivedita@xxxxxxxxxxxx>
Reported-by: kernelci.org bot <bot@xxxxxxxxxxxx>
Reported-by: Mark Brown <broonie@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
---
MAINTAINERS | 1 +
init/Kconfig | 9 ++++++++-
scripts/lld-version.sh | 20 ++++++++++++++++++++
3 files changed, 29 insertions(+), 1 deletion(-)
create mode 100755 scripts/lld-version.sh

diff --git a/MAINTAINERS b/MAINTAINERS
index e451dcce054f..e6f74f130ae1 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..b9037d6c5ab3 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 +1353,10 @@ 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 y
+ depends on ARCH_WANT_LD_ORPHAN_WARN
+ depends on !LD_IS_LLD || LLD_VERSION >= 110000
+ depends on $(ld-option,--orphan-handling=warn)

config SYSCTL
bool
diff --git a/scripts/lld-version.sh b/scripts/lld-version.sh
new file mode 100755
index 000000000000..d70edb4d8a4f
--- /dev/null
+++ b/scripts/lld-version.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+#
+# Usage: $ ./scripts/lld-version.sh ld.lld
+#
+# Print the linker version of `ld.lld' in a 5 or 6-digit form
+# such as `100001' for ld.lld 10.0.1 etc.
+
+linker_string="$($* --version)"
+
+if ! ( echo $linker_string | grep -q LLD ); then
+ echo 0
+ exit 1
+fi
+
+VERSION=$(echo $linker_string | cut -d ' ' -f 2)
+MAJOR=$(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