Commit 15d5761a authored by Masahiro Yamada's avatar Masahiro Yamada

kbuild: introduce ccflags-remove-y and asflags-remove-y

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

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 2464a609 ("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: default avatarSami Tolvanen <samitolvanen@google.com>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Acked-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Brendan Higgins <brendanhiggins@google.com> (KUnit)
Tested-by: default avatarAnders Roxell <anders.roxell@linaro.org>
parent 3ec8a5b3
......@@ -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
......
......@@ -102,13 +102,9 @@ 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.
......
......@@ -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
......
......@@ -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 $(obj)/../../kernel/vmlinux.lds
......
......@@ -2,9 +2,9 @@
# Do not instrument the tracer itself:
ccflags-remove-$(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
......
# 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
......@@ -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) += $(CC_FLAGS_FTRACE)
# These files are disabled because they produce lots of non-interesting and/or
# flaky coverage that is not a function of syscall inputs. For example,
......
# SPDX-License-Identifier: GPL-2.0
ccflags-remove-$(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
......
......@@ -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
# 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
......
ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_KUNIT) += kunit.o
kunit-objs += test.o \
......
......@@ -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 \
......
# 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-$(CONFIG_LZ4HC_COMPRESS) += lz4hc_compress.o
......
# SPDX-License-Identifier: GPL-2.0-only
ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
lzo_compress-objs := lzo1x_compress.o
lzo_decompress-objs := lzo1x_decompress_safe.o
......
# SPDX-License-Identifier: GPL-2.0-only
ccflags-remove-$(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
......
......@@ -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 = \
......
# 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 \
......
......@@ -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-$(CONFIG_REED_SOLOMON_TEST) += test_rslib.o
# SPDX-License-Identifier: GPL-2.0-only
ccflags-remove-$(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-$(CONFIG_XZ_DEC_BCJ) += xz_dec_bcj.o
......
......@@ -7,6 +7,8 @@
# decompression code.
#
ccflags-remove-$(CONFIG_FUNCTION_TRACER) += $(CC_FLAGS_FTRACE)
obj-$(CONFIG_ZLIB_DEFLATE) += zlib_deflate.o
zlib_deflate-objs := deflate.o deftree.o deflate_syms.o
......@@ -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
......@@ -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 \
......
......@@ -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) += $(CC_FLAGS_FTRACE)
zstd_compress-y := fse_compress.o huf_compress.o compress.o \
entropy_common.o fse_decompress.o zstd_common.o
......
......@@ -111,12 +111,14 @@ basename_flags = -DKBUILD_BASENAME=$(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)
#
......
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