[Devel] [PATCH hci-8.1 2/2] ms/kbuild: move GCOV flags to scripts/Makefile.gcov

[Konstantin Khorenko]

 * 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 <khorenko at virtuozzo.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Suggested-by: Peter Oberparleiter <oberpar at linux.ibm.com>
Cc: Nathan Chancellor <nathan at kernel.org>
Cc: Nicolas Schier <nsc at kernel.org>
Cc: Masahiro Yamada <masahiroy at kernel.org>
Cc: Arnd Bergmann <arnd at arndb.de>
Cc: Mikhail Zaslonko <zaslonko at linux.ibm.com>
(cherry picked from commit f541906e89f9d08ef29f058b6cef1db071cd8163)
Picked from the akpm/mm tree, branch mm-nonmm-stable: not in Linus's
tree yet.

Conflict in Makefile: the CFLAGS_GCOV block sits next to different
lines in this tree. Removed the block and kept the local context.

https://virtuozzo.atlassian.net/browse/VSTOR-148131
Feature: fix ms/gcov
Assisted-by: LLM
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 MAINTAINERS           |  1 +
 Makefile              | 22 +---------------------
 scripts/Makefile.gcov | 21 +++++++++++++++++++++
 3 files changed, 23 insertions(+), 21 deletions(-)

diff --git a/MAINTAINERS b/MAINTAINERS
index 9523da3c767cb..f0f955907fd7d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9535,6 +9535,7 @@ M:	Peter Oberparleiter <oberpar at linux.ibm.com>
 S:	Maintained
 F:	Documentation/dev-tools/gcov.rst
 F:	kernel/gcov/
+F:	scripts/Makefile.gcov
 
 GDB KERNEL DEBUGGING HELPER SCRIPTS
 M:	Jan Kiszka <jan.kiszka at siemens.com>
diff --git a/Makefile b/Makefile
index 3524889b5bb5f..7c8f8e9b9be99 100644
--- a/Makefile
+++ b/Makefile
@@ -1033,27 +1033,6 @@ ifdef CONFIG_CC_IS_GCC
 KBUILD_CFLAGS   += -fconserve-stack
 endif
 
-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 from the srctree
 KBUILD_CPPFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
 
@@ -1066,6 +1045,7 @@ 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-$(CONFIG_AUTOFDO_CLANG)	+= scripts/Makefile.autofdo
 include-$(CONFIG_PROPELLER_CLANG)	+= scripts/Makefile.propeller
diff --git a/scripts/Makefile.gcov b/scripts/Makefile.gcov
new file mode 100644
index 0000000000000..16c5b876440c2
--- /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

-- 
2.43.0