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-rw-r--r--Makefile29
1 files changed, 22 insertions, 7 deletions
diff --git a/Makefile b/Makefile
index 9c16001ccdcd..7ee3beedceca 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
VERSION = 6
PATCHLEVEL = 18
-SUBLEVEL = 37
+SUBLEVEL = 38
EXTRAVERSION =
NAME = Baby Opossum Posse
@@ -806,12 +806,6 @@ endif # KBUILD_EXTMOD
# Defaults to vmlinux, but the arch makefile usually adds further targets
all: vmlinux
-CFLAGS_GCOV := -fprofile-arcs -ftest-coverage
-ifdef CONFIG_CC_IS_GCC
-CFLAGS_GCOV += -fno-tree-loop-im
-endif
-export CFLAGS_GCOV
-
# The arch Makefiles can override CC_FLAGS_FTRACE. We may also append it later.
ifdef CONFIG_FUNCTION_TRACER
CC_FLAGS_FTRACE := -pg
@@ -1082,6 +1076,27 @@ 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 -fprofile-arcs \
+ -ftest-coverage -x c - -c -o "$$TMP.base" && \
+ echo 'long long x; void f(void){x++;}' | \
+ $(CC) $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) -w -fprofile-arcs \
+ -ftest-coverage -fprofile-update=prefer-atomic \
+ -x c - -c -o "$$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 += $(call cc-option,-fmacro-prefix-map=$(srcroot)/=)