From d3e7732253e6552011ccd4b7fc116821c032db76 Mon Sep 17 00:00:00 2001 From: Konstantin Khorenko Date: Thu, 1 Oct 2026 18:57:12 +0200 Subject: kbuild: move GCOV flags to scripts/Makefile.gcov * split the CFLAGS_GCOV block out of the top-level Makefile into scripts/Makefile.gcov * include it via include-$(CONFIG_GCOV_KERNEL) like neighbour KASAN/KCOV/UBSAN makefiles do * keep the include before scripts/Makefile.gcc-plugins: the try-run must not get -fplugin= options, plugins do not exist on clean builds CFLAGS_GCOV is no longer defined when CONFIG_GCOV_KERNEL is off: * its user in scripts/Makefile.lib is guarded by the CONFIG_GCOV_KERNEL * in i915/xe header an empty value is harmless The try-run compiler invocations also stop running on builds without GCOV. Link: https://lore.kernel.org/20261001-b4-prep-gcov-v1-2-794792e06f24@virtuozzo.com Signed-off-by: Konstantin Khorenko Signed-off-by: Andrew Morton Suggested-by: Peter Oberparleiter Cc: Nathan Chancellor Cc: Nicolas Schier Cc: Masahiro Yamada Cc: Arnd Bergmann Cc: Mikhail Zaslonko --- scripts/Makefile.gcov | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 scripts/Makefile.gcov (limited to 'scripts') diff --git a/scripts/Makefile.gcov b/scripts/Makefile.gcov new file mode 100644 index 000000000000..16c5b876440c --- /dev/null +++ b/scripts/Makefile.gcov @@ -0,0 +1,21 @@ +# SPDX-License-Identifier: GPL-2.0-only +CFLAGS_GCOV := -fprofile-arcs -ftest-coverage +ifdef CONFIG_CC_IS_GCC +CFLAGS_GCOV += -fno-tree-loop-im +# Use atomic counter updates to avoid concurrent-access crashes in GCOV. +# Only enable if -fprofile-update=prefer-atomic does not introduce new +# undefined symbols (e.g. libatomic calls that the kernel cannot link). +CFLAGS_GCOV += $(call try-run,\ + echo 'long long x; void f(void){x++;}' | \ + $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -w $(CFLAGS_GCOV) \ + -x c - -c -o "$$TMP.base" && \ + echo 'long long x; void f(void){x++;}' | \ + $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -w $(CFLAGS_GCOV) \ + -fprofile-update=prefer-atomic \ + -x c - -c -o "$$TMP" && \ + $(NM) "$$TMP.base" | grep ' U ' > "$$TMP.ubase" || true ; \ + $(NM) "$$TMP" | grep ' U ' > "$$TMP.utest" || true ; \ + cmp -s "$$TMP.ubase" "$$TMP.utest",\ + -fprofile-update=prefer-atomic) +endif +export CFLAGS_GCOV -- cgit v1.2.3