On Tue, 7 Jul 2020 at 11:21, Masahiro Yamada masahiroy@kernel.org wrote:
CFLAGS_REMOVE_<file>.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_<file> adds compiler flags per file.
[5] CFLAGS_REMOVE_<file> 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
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.
arch/arm/boot/compressed/ arch/powerpc/xmon/ arch/sh/ kernel/trace/
... have no sub-directories.
lib/
... has several sub-directories.
To keep the behavior, I added ccflags-remove-y to all Makefiles in subdirectories of lib/, except:
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 later commit, I will try to remove ccflags-remove-y from sub-directory Makefiles.
Suggested-by: Sami Tolvanen samitolvanen@google.com Signed-off-by: Masahiro Yamada masahiroy@kernel.org Acked-by: Steven Rostedt (VMware) rostedt@goodmis.org Acked-by: Michael Ellerman mpe@ellerman.id.au (powerpc)
Tested-by: Anders Roxell anders.roxell@linaro.org
Changes in v2:
- Swap the order of [3] and [4] to keep the current behavior of kernel/trace/Makefile.
- Add ccflags-remove-y to subdir Makefiles of lib/
Documentation/kbuild/makefiles.rst | 14 ++++++++++++++ arch/arm/boot/compressed/Makefile | 6 +----- arch/powerpc/xmon/Makefile | 3 +-- arch/sh/boot/compressed/Makefile | 5 +---- kernel/trace/Makefile | 4 ++-- lib/842/Makefile | 3 +++ lib/Makefile | 5 +---- lib/crypto/Makefile | 2 ++ lib/dim/Makefile | 2 ++ lib/fonts/Makefile | 2 ++ lib/kunit/Makefile | 3 +++ lib/livepatch/Makefile | 2 ++ lib/lz4/Makefile | 1 + lib/lzo/Makefile | 2 ++ lib/math/Makefile | 2 ++ lib/mpi/Makefile | 2 ++ lib/raid6/Makefile | 3 +++ lib/reed_solomon/Makefile | 2 ++ lib/xz/Makefile | 3 +++ lib/zlib_deflate/Makefile | 2 ++ lib/zlib_dfltcc/Makefile | 2 ++ lib/zlib_inflate/Makefile | 2 ++ lib/zstd/Makefile | 1 + scripts/Makefile.lib | 14 ++++++++------ 24 files changed, 64 insertions(+), 23 deletions(-)
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst index 6515ebc12b6f..14d8e7d23c04 100644 --- a/Documentation/kbuild/makefiles.rst +++ b/Documentation/kbuild/makefiles.rst @@ -368,6 +368,14 @@ more details, with real examples.
subdir-ccflags-y := -Werror
- ccflags-remove-y, asflags-remove-y
These flags are used to remove particular flags for the compiler,assembler invocations.Example::ccflags-remove-$(CONFIG_MCOUNT) += -pg- CFLAGS_$@, AFLAGS_$@ CFLAGS_$@ and AFLAGS_$@ only apply to commands in current kbuild makefile.
@@ -375,6 +383,9 @@ more details, with real examples. $(CFLAGS_$@) specifies per-file options for $(CC). The $@ part has a literal value which specifies the file that it is for.
CFLAGS_$@ has the higher priority than ccflags-remove-y; CFLAGS_$@can re-add compiler flags that were removed by ccflags-remove-y.Example:: # drivers/scsi/Makefile@@ -387,6 +398,9 @@ more details, with real examples. $(AFLAGS_$@) is a similar feature for source files in assembly languages.
AFLAGS_$@ has the higher priority than asflags-remove-y; AFLAGS_$@can re-add assembler flags that were removed by asflags-remove-y.Example:: # arch/arm/kernel/Makefilediff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index 00602a6fba04..3d5691b23951 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -103,13 +103,9 @@ clean-files += piggy_data lib1funcs.S ashldi3.S bswapsdi2.S hyp-stub.S
KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
-ifeq ($(CONFIG_FUNCTION_TRACER),y) -ORIG_CFLAGS := $(KBUILD_CFLAGS) -KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS)) -endif
ccflags-y := -fpic $(call cc-option,-mno-single-pic-base,) -fno-builtin \ -I$(obj) $(DISABLE_ARM_SSP_PER_TASK_PLUGIN) +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += -pg asflags-y := -DZIMAGE
# Supply kernel BSS size to the decompressor via a linker symbol. diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile index 89c76ca35640..eb25d7554ffd 100644 --- a/arch/powerpc/xmon/Makefile +++ b/arch/powerpc/xmon/Makefile @@ -7,8 +7,7 @@ UBSAN_SANITIZE := n KASAN_SANITIZE := n
# Disable ftrace for the entire directory -ORIG_CFLAGS := $(KBUILD_CFLAGS) -KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS)) +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
ifdef CONFIG_CC_IS_CLANG # clang stores addresses on the stack causing the frame size to blow diff --git a/arch/sh/boot/compressed/Makefile b/arch/sh/boot/compressed/Makefile index ad0e2403e56f..589d2d8a573d 100644 --- a/arch/sh/boot/compressed/Makefile +++ b/arch/sh/boot/compressed/Makefile @@ -28,10 +28,7 @@ IMAGE_OFFSET := $(shell /bin/bash -c 'printf "0x%08x" \ $(CONFIG_BOOT_LINK_OFFSET)]') endif
-ifeq ($(CONFIG_MCOUNT),y) -ORIG_CFLAGS := $(KBUILD_CFLAGS) -KBUILD_CFLAGS = $(subst -pg, , $(ORIG_CFLAGS)) -endif +ccflags-remove-$(CONFIG_MCOUNT) += -pg
LDFLAGS_vmlinux := --oformat $(ld-bfd) -Ttext $(IMAGE_OFFSET) -e startup \ -T $(obj)/../../kernel/vmlinux.lds diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile index 6575bb0a0434..7492844a8b1b 100644 --- a/kernel/trace/Makefile +++ b/kernel/trace/Makefile @@ -2,9 +2,9 @@
# Do not instrument the tracer itself:
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
ifdef CONFIG_FUNCTION_TRACER -ORIG_CFLAGS := $(KBUILD_CFLAGS) -KBUILD_CFLAGS = $(subst $(CC_FLAGS_FTRACE),,$(ORIG_CFLAGS))
# Avoid recursion due to instrumentation. KCSAN_SANITIZE := n diff --git a/lib/842/Makefile b/lib/842/Makefile index 6f7aad269288..b815e824ae37 100644 --- a/lib/842/Makefile +++ b/lib/842/Makefile @@ -1,3 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_842_COMPRESS) += 842_compress.o obj-$(CONFIG_842_DECOMPRESS) += 842_decompress.o diff --git a/lib/Makefile b/lib/Makefile index b1c42c10073b..b2ed4beddd68 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) += $(CC_FLAGS_FTRACE)
# These files are disabled because they produce lots of non-interesting and/or # flaky coverage that is not a function of syscall inputs. For example, diff --git a/lib/crypto/Makefile b/lib/crypto/Makefile index 3a435629d9ce..b557ef0b07c2 100644 --- a/lib/crypto/Makefile +++ b/lib/crypto/Makefile @@ -1,5 +1,7 @@ # SPDX-License-Identifier: GPL-2.0
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
# chacha is used by the /dev/random driver which is always builtin obj-y += chacha.o obj-$(CONFIG_CRYPTO_LIB_CHACHA_GENERIC) += libchacha.o diff --git a/lib/dim/Makefile b/lib/dim/Makefile index 1d6858a108cb..97fc3e89d34e 100644 --- a/lib/dim/Makefile +++ b/lib/dim/Makefile @@ -2,6 +2,8 @@ # DIM Dynamic Interrupt Moderation library #
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_DIMLIB) += dim.o
dim-y := dim.o net_dim.o rdma_dim.o diff --git a/lib/fonts/Makefile b/lib/fonts/Makefile index ed95070860de..f951750c179e 100644 --- a/lib/fonts/Makefile +++ b/lib/fonts/Makefile @@ -1,6 +1,8 @@ # SPDX-License-Identifier: GPL-2.0 # Font handling
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
font-objs := fonts.o
font-objs-$(CONFIG_FONT_SUN8x16) += font_sun8x16.o diff --git a/lib/kunit/Makefile b/lib/kunit/Makefile index 724b94311ca3..8c847557ab24 100644 --- a/lib/kunit/Makefile +++ b/lib/kunit/Makefile @@ -1,3 +1,6 @@
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_KUNIT) += kunit.o
kunit-objs += test.o \ diff --git a/lib/livepatch/Makefile b/lib/livepatch/Makefile index 295b94bff370..9abdf615b088 100644 --- a/lib/livepatch/Makefile +++ b/lib/livepatch/Makefile @@ -2,6 +2,8 @@ # # Makefile for livepatch test code.
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_TEST_LIVEPATCH) += test_klp_atomic_replace.o \ test_klp_callbacks_demo.o \ test_klp_callbacks_demo2.o \ diff --git a/lib/lz4/Makefile b/lib/lz4/Makefile index 5b42242afaa2..53da4cab7015 100644 --- a/lib/lz4/Makefile +++ b/lib/lz4/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only ccflags-y += -O3 +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_LZ4_COMPRESS) += lz4_compress.o obj-$(CONFIG_LZ4HC_COMPRESS) += lz4hc_compress.o diff --git a/lib/lzo/Makefile b/lib/lzo/Makefile index 2f58fafbbddd..9565a555275b 100644 --- a/lib/lzo/Makefile +++ b/lib/lzo/Makefile @@ -1,4 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
lzo_compress-objs := lzo1x_compress.o lzo_decompress-objs := lzo1x_decompress_safe.o
diff --git a/lib/math/Makefile b/lib/math/Makefile index be6909e943bd..49aa50e28185 100644 --- a/lib/math/Makefile +++ b/lib/math/Makefile @@ -1,4 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-y += div64.o gcd.o lcm.o int_pow.o int_sqrt.o reciprocal_div.o
obj-$(CONFIG_CORDIC) += cordic.o diff --git a/lib/mpi/Makefile b/lib/mpi/Makefile index d5874a7f5ff9..df7883521619 100644 --- a/lib/mpi/Makefile +++ b/lib/mpi/Makefile @@ -3,6 +3,8 @@ # MPI multiprecision maths library (from gpg) #
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_MPILIB) = mpi.o
mpi-y = \ diff --git a/lib/raid6/Makefile b/lib/raid6/Makefile index b4c0df6d706d..3482d6ae3f3b 100644 --- a/lib/raid6/Makefile +++ b/lib/raid6/Makefile @@ -1,4 +1,7 @@ # SPDX-License-Identifier: GPL-2.0
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_RAID6_PQ) += raid6_pq.o
raid6_pq-y += algos.o recov.o tables.o int1.o int2.o int4.o \ diff --git a/lib/reed_solomon/Makefile b/lib/reed_solomon/Makefile index 5d4fa68f26cb..a5c9defdac7f 100644 --- a/lib/reed_solomon/Makefile +++ b/lib/reed_solomon/Makefile @@ -3,5 +3,7 @@ # This is a modified version of reed solomon lib, #
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_REED_SOLOMON) += reed_solomon.o obj-$(CONFIG_REED_SOLOMON_TEST) += test_rslib.o diff --git a/lib/xz/Makefile b/lib/xz/Makefile index fa6af814a8d1..fae9b6c7c389 100644 --- a/lib/xz/Makefile +++ b/lib/xz/Makefile @@ -1,4 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_XZ_DEC) += xz_dec.o xz_dec-y := xz_dec_syms.o xz_dec_stream.o xz_dec_lzma2.o xz_dec-$(CONFIG_XZ_DEC_BCJ) += xz_dec_bcj.o diff --git a/lib/zlib_deflate/Makefile b/lib/zlib_deflate/Makefile index 2622e03c0b94..1fcefe73536f 100644 --- a/lib/zlib_deflate/Makefile +++ b/lib/zlib_deflate/Makefile @@ -7,6 +7,8 @@ # decompression code. #
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate.o
zlib_deflate-objs := deflate.o deftree.o deflate_syms.o diff --git a/lib/zlib_dfltcc/Makefile b/lib/zlib_dfltcc/Makefile index 8e4d5afbbb10..7a8067f6e772 100644 --- a/lib/zlib_dfltcc/Makefile +++ b/lib/zlib_dfltcc/Makefile @@ -6,6 +6,8 @@ # This is the code for s390 zlib hardware support. #
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_ZLIB_DFLTCC) += zlib_dfltcc.o
zlib_dfltcc-objs := dfltcc.o dfltcc_deflate.o dfltcc_inflate.o dfltcc_syms.o diff --git a/lib/zlib_inflate/Makefile b/lib/zlib_inflate/Makefile index 27327d3e9f54..a451e96f9845 100644 --- a/lib/zlib_inflate/Makefile +++ b/lib/zlib_inflate/Makefile @@ -14,6 +14,8 @@ # uncompression can be done without blocking on allocation). #
+ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_ZLIB_INFLATE) += zlib_inflate.o
zlib_inflate-objs := inffast.o inflate.o infutil.o \ diff --git a/lib/zstd/Makefile b/lib/zstd/Makefile index f5d778e7e5c7..01be908a2d94 100644 --- a/lib/zstd/Makefile +++ b/lib/zstd/Makefile @@ -3,6 +3,7 @@ obj-$(CONFIG_ZSTD_COMPRESS) += zstd_compress.o obj-$(CONFIG_ZSTD_DECOMPRESS) += zstd_decompress.o
ccflags-y += -O3 +ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
zstd_compress-y := fse_compress.o huf_compress.o compress.o \ entropy_common.o fse_decompress.o zstd_common.o diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 916b2f7f7098..3629f66646d7 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -111,12 +111,14 @@ basename_flags = -DKBUILD_BASENAME=$(call name-fix,$(basetarget)) modname_flags = -DKBUILD_MODNAME=$(call name-fix,$(modname)) modfile_flags = -DKBUILD_MODFILE=$(call stringify,$(modfile))
-orig_c_flags = $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) \
$(ccflags-y) $(CFLAGS_$(target-stem).o)-_c_flags = $(filter-out $(CFLAGS_REMOVE_$(target-stem).o), $(orig_c_flags)) -orig_a_flags = $(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) \
$(asflags-y) $(AFLAGS_$(target-stem).o)-_a_flags = $(filter-out $(AFLAGS_REMOVE_$(target-stem).o), $(orig_a_flags)) +_c_flags = $(filter-out $(CFLAGS_REMOVE_$(target-stem).o), \
$(filter-out $(ccflags-remove-y), \$(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS) $(ccflags-y)) \$(CFLAGS_$(target-stem).o))+_a_flags = $(filter-out $(AFLAGS_REMOVE_$(target-stem).o), \
$(filter-out $(asflags-remove-y), \$(KBUILD_CPPFLAGS) $(KBUILD_AFLAGS) $(asflags-y)) \$(AFLAGS_$(target-stem).o))_cpp_flags = $(KBUILD_CPPFLAGS) $(cppflags-y) $(CPPFLAGS_$(target-stem).lds)
#
2.25.1