From f541906e89f9d08ef29f058b6cef1db071cd8163 Mon Sep 17 00:00:00 2001 From: Konstantin Khorenko Date: Thu, 1 Oct 2026 18:57:12 +0200 Subject: [PATCH] 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 --- MAINTAINERS | 1 + Makefile | 22 +--------------------- scripts/Makefile.gcov | 21 +++++++++++++++++++++ 3 files changed, 23 insertions(+), 21 deletions(-) create mode 100644 scripts/Makefile.gcov diff --git a/MAINTAINERS b/MAINTAINERS index d642d4168c28..bd6619bc107d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -10899,6 +10899,7 @@ M: Peter Oberparleiter S: Maintained F: Documentation/dev-tools/gcov.rst F: kernel/gcov/ +F: scripts/Makefile.gcov GDB KERNEL DEBUGGING HELPER SCRIPTS M: Jan Kiszka diff --git a/Makefile b/Makefile index 3b69b973f759..f3ea94ceb1ce 100644 --- a/Makefile +++ b/Makefile @@ -1176,27 +1176,6 @@ endif # Ensure compilers do not transform certain loops into calls to wcslen() KBUILD_CFLAGS += -fno-builtin-wcslen -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 - # change __FILE__ to the relative path to the source directory ifdef building_out_of_srctree KBUILD_CPPFLAGS += -fmacro-prefix-map=$(srcroot)/= @@ -1214,6 +1193,7 @@ include-$(CONFIG_KCSAN) += scripts/Makefile.kcsan include-$(CONFIG_KMSAN) += scripts/Makefile.kmsan include-$(CONFIG_UBSAN) += scripts/Makefile.ubsan include-$(CONFIG_KCOV) += scripts/Makefile.kcov +include-$(CONFIG_GCOV_KERNEL) += scripts/Makefile.gcov include-$(CONFIG_RANDSTRUCT) += scripts/Makefile.randstruct include-$(CONFIG_KSTACK_ERASE) += scripts/Makefile.kstack_erase include-$(CONFIG_AUTOFDO_CLANG) += scripts/Makefile.autofdo 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