From 15d5761ad31dfb194ebe76554e6af0437eb20424 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 7 Jul 2020 18:21:16 +0900 Subject: kbuild: introduce ccflags-remove-y and asflags-remove-y CFLAGS_REMOVE_.o filters out flags when compiling a particular object, but there is no convenient way to do that for every object in a directory. Add ccflags-remove-y and asflags-remove-y to make it easily. Use ccflags-remove-y to clean up some Makefiles. The add/remove order works as follows: [1] KBUILD_CFLAGS specifies compiler flags used globally [2] ccflags-y adds compiler flags for all objects in the current Makefile [3] ccflags-remove-y removes compiler flags for all objects in the current Makefile (New feature) [4] CFLAGS_ adds compiler flags per file. [5] CFLAGS_REMOVE_ removes compiler flags per file. Having [3] before [4] allows us to remove flags from most (but not all) objects in the current Makefile. For example, kernel/trace/Makefile removes $(CC_FLAGS_FTRACE) from all objects in the directory, then adds it back to trace_selftest_dynamic.o and CFLAGS_trace_kprobe_selftest.o The same applies to lib/livepatch/Makefile. Please note ccflags-remove-y has no effect to the sub-directories. In contrast, the previous notation got rid of compiler flags also from all the sub-directories. The following are not affected because they have no sub-directories: arch/arm/boot/compressed/ arch/powerpc/xmon/ arch/sh/ kernel/trace/ However, lib/ has several sub-directories. To keep the behavior, I added ccflags-remove-y to all Makefiles in subdirectories of lib/, except the following: lib/vdso/Makefile - Kbuild does not descend into this Makefile lib/raid/test/Makefile - This is not used for the kernel build I think commit 2464a609ded0 ("ftrace: do not trace library functions") excluded too much. In the next commit, I will remove ccflags-remove-y from the sub-directories of lib/. Suggested-by: Sami Tolvanen Signed-off-by: Masahiro Yamada Acked-by: Steven Rostedt (VMware) Acked-by: Michael Ellerman (powerpc) Acked-by: Brendan Higgins (KUnit) Tested-by: Anders Roxell --- lib/Makefile | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) (limited to 'lib/Makefile') diff --git a/lib/Makefile b/lib/Makefile index 0cda70649f1c..233f6e644eeb 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -3,10 +3,7 @@ # Makefile for some libs needed in the kernel. # -ifdef CONFIG_FUNCTION_TRACER -ORIG_CFLAGS := $(KBUILD_CFLAGS) -KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS)) -endif +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE) # These files are disabled because they produce lots of non-interesting and/or # flaky coverage that is not a function of syscall inputs. For example, -- cgit