[PATCH] kbuild: mkcompile_h: Include $LD version in /proc/version

Kees Cook
2020-04-02T08:18:42Z

When doing Clang builds of the kernel, it is possible to link with
either ld.bfd (binutils) or ld.lld (LLVM), but it is not possible to
discover this from a running kernel. Add the "$LD -v" output to
/proc/version.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
init/Makefile | 2 +-
scripts/mkcompile_h | 8 ++++++--
2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/init/Makefile b/init/Makefile
index 6246a06364d0..82c15bdb42d7 100644
--- a/init/Makefile
+++ b/init/Makefile
@@ -35,4 +35,4 @@ include/generated/compile.h: FORCE
@$($(quiet)chk_compile.h)
$(Q)$(CONFIG_SHELL) $(srctree)/scripts/mkcompile_h $@ \
"$(UTS_MACHINE)" "$(CONFIG_SMP)" "$(CONFIG_PREEMPT)" \
- "$(CONFIG_PREEMPT_RT)" "$(CC) $(KBUILD_CFLAGS)"
+ "$(CONFIG_PREEMPT_RT)" "$(LD)" "$(CC) $(KBUILD_CFLAGS)"
diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h
index 3a5a4b210c86..f98c07709370 100755
--- a/scripts/mkcompile_h
+++ b/scripts/mkcompile_h
@@ -6,7 +6,8 @@ ARCH=$2
SMP=$3
PREEMPT=$4
PREEMPT_RT=$5
-CC=$6
+LD=$6
+CC=$7

vecho() { [ "${quiet}" = "silent_" ] || echo "$@" ; }

@@ -72,7 +73,10 @@ UTS_VERSION="$(echo $UTS_VERSION $CONFIG_FLAGS $TIMESTAMP | cut -b -$UTS_LEN)"
printf '#define LINUX_COMPILE_BY "%s"\n' "$LINUX_COMPILE_BY"
echo \#define LINUX_COMPILE_HOST \"$LINUX_COMPILE_HOST\"

- echo \#define LINUX_COMPILER \"`$CC -v 2>&1 | grep ' version ' | sed 's/[[:space:]]*$//'`\"
+ CC_VERSION=$($CC -v 2>&1 | grep ' version ' | sed 's/[[:space:]]*$//')
+ LD_VERSION=$($LD -v | head -n1 | sed 's/(compatible with [^)]*)//' \
+ | sed 's/[[:space:]]*$//')
+ printf '#define LINUX_COMPILER "%s"\n' "$CC_VERSION, $LD_VERSION"
} > .tmpcompile

# Only replace the real compile.h if the new one is different,
--
2.20.1

--
Kees Cook