| Message ID | 20200707092117.963394-1-masahiroy@kernel.org (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | [v2,1/2] kbuild: introduce ccflags-remove-y and asflags-remove-y | expand |
On Tue, Jul 7, 2020 at 2:22 AM 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) Acked-by: Brendan Higgins <brendanhiggins@google.com> (KUnit)
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/Makefile > diff --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 >
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/Makefile diff --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) #
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) --- 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(-)