mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-28 07:13:34 +00:00
ad7a953c52
This patch changes the way __crc_ symbols are being resolved from using ld to do so to using the assembler, thus allowing these symbols to be marked local (the linker creates then as global ones) and hence allow stripping (for modules) or ignoring (for vmlinux) them. While at this, also strip other generated symbols during module installation. One potentially debatable point is the handling of the flags passeed to gcc when translating the intermediate assembly file into an object: passing $(c_flags) unchanged doesn't work as gcc passes --gdwarf2 to gas whenever is sees any -g* option, even for -g0, and despite the fact that the compiler would have already produced all necessary debug info in the C->assembly translation phase. I took the approach of just filtering out all -g* options, but an alternative to such negative filtering might be to have a positive filter which might, in the ideal case allow just all the -Wa,* options to pass through. Signed-off-by: Jan Beulich <jbeulich@novell.com> Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
405 lines
12 KiB
Makefile
405 lines
12 KiB
Makefile
# ==========================================================================
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# Building
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# ==========================================================================
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src := $(obj)
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PHONY := __build
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__build:
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# Init all relevant variables used in kbuild files so
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# 1) they have correct type
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# 2) they do not inherit any value from the environment
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obj-y :=
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obj-m :=
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lib-y :=
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lib-m :=
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always :=
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targets :=
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subdir-y :=
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subdir-m :=
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EXTRA_AFLAGS :=
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EXTRA_CFLAGS :=
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EXTRA_CPPFLAGS :=
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EXTRA_LDFLAGS :=
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asflags-y :=
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ccflags-y :=
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cppflags-y :=
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ldflags-y :=
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# Read auto.conf if it exists, otherwise ignore
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-include include/config/auto.conf
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include scripts/Kbuild.include
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# For backward compatibility check that these variables do not change
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save-cflags := $(CFLAGS)
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# The filename Kbuild has precedence over Makefile
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kbuild-dir := $(if $(filter /%,$(src)),$(src),$(srctree)/$(src))
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kbuild-file := $(if $(wildcard $(kbuild-dir)/Kbuild),$(kbuild-dir)/Kbuild,$(kbuild-dir)/Makefile)
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include $(kbuild-file)
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# If the save-* variables changed error out
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ifeq ($(KBUILD_NOPEDANTIC),)
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ifneq ("$(save-cflags)","$(CFLAGS)")
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$(error CFLAGS was changed in "$(kbuild-file)". Fix it to use EXTRA_CFLAGS)
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endif
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endif
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include scripts/Makefile.lib
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ifdef host-progs
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ifneq ($(hostprogs-y),$(host-progs))
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$(warning kbuild: $(obj)/Makefile - Usage of host-progs is deprecated. Please replace with hostprogs-y!)
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hostprogs-y += $(host-progs)
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endif
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endif
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# Do not include host rules unless needed
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ifneq ($(hostprogs-y)$(hostprogs-m),)
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include scripts/Makefile.host
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endif
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ifneq ($(KBUILD_SRC),)
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# Create output directory if not already present
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_dummy := $(shell [ -d $(obj) ] || mkdir -p $(obj))
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# Create directories for object files if directory does not exist
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# Needed when obj-y := dir/file.o syntax is used
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_dummy := $(foreach d,$(obj-dirs), $(shell [ -d $(d) ] || mkdir -p $(d)))
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endif
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ifndef obj
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$(warning kbuild: Makefile.build is included improperly)
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endif
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# ===========================================================================
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ifneq ($(strip $(lib-y) $(lib-m) $(lib-n) $(lib-)),)
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lib-target := $(obj)/lib.a
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endif
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ifneq ($(strip $(obj-y) $(obj-m) $(obj-n) $(obj-) $(lib-target)),)
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builtin-target := $(obj)/built-in.o
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endif
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modorder-target := $(obj)/modules.order
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# We keep a list of all modules in $(MODVERDIR)
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__build: $(if $(KBUILD_BUILTIN),$(builtin-target) $(lib-target) $(extra-y)) \
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$(if $(KBUILD_MODULES),$(obj-m) $(modorder-target)) \
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$(subdir-ym) $(always)
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@:
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# Linus' kernel sanity checking tool
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ifneq ($(KBUILD_CHECKSRC),0)
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ifeq ($(KBUILD_CHECKSRC),2)
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quiet_cmd_force_checksrc = CHECK $<
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cmd_force_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
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else
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quiet_cmd_checksrc = CHECK $<
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cmd_checksrc = $(CHECK) $(CHECKFLAGS) $(c_flags) $< ;
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endif
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endif
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# Do section mismatch analysis for each module/built-in.o
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ifdef CONFIG_DEBUG_SECTION_MISMATCH
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cmd_secanalysis = ; scripts/mod/modpost $@
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endif
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# Compile C sources (.c)
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# ---------------------------------------------------------------------------
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# Default is built-in, unless we know otherwise
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modkern_cflags := $(CFLAGS_KERNEL)
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quiet_modtag := $(empty) $(empty)
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$(real-objs-m) : modkern_cflags := $(CFLAGS_MODULE)
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$(real-objs-m:.o=.i) : modkern_cflags := $(CFLAGS_MODULE)
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$(real-objs-m:.o=.s) : modkern_cflags := $(CFLAGS_MODULE)
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$(real-objs-m:.o=.lst): modkern_cflags := $(CFLAGS_MODULE)
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$(real-objs-m) : quiet_modtag := [M]
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$(real-objs-m:.o=.i) : quiet_modtag := [M]
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$(real-objs-m:.o=.s) : quiet_modtag := [M]
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$(real-objs-m:.o=.lst): quiet_modtag := [M]
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$(obj-m) : quiet_modtag := [M]
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# Default for not multi-part modules
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modname = $(basetarget)
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$(multi-objs-m) : modname = $(modname-multi)
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$(multi-objs-m:.o=.i) : modname = $(modname-multi)
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$(multi-objs-m:.o=.s) : modname = $(modname-multi)
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$(multi-objs-m:.o=.lst) : modname = $(modname-multi)
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$(multi-objs-y) : modname = $(modname-multi)
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$(multi-objs-y:.o=.i) : modname = $(modname-multi)
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$(multi-objs-y:.o=.s) : modname = $(modname-multi)
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$(multi-objs-y:.o=.lst) : modname = $(modname-multi)
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quiet_cmd_cc_s_c = CC $(quiet_modtag) $@
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cmd_cc_s_c = $(CC) $(c_flags) -fverbose-asm -S -o $@ $<
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$(obj)/%.s: $(src)/%.c FORCE
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$(call if_changed_dep,cc_s_c)
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quiet_cmd_cc_i_c = CPP $(quiet_modtag) $@
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cmd_cc_i_c = $(CPP) $(c_flags) -o $@ $<
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$(obj)/%.i: $(src)/%.c FORCE
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$(call if_changed_dep,cc_i_c)
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cmd_genksyms = \
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$(CPP) -D__GENKSYMS__ $(c_flags) $< | \
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$(GENKSYMS) -T $@ -A -a $(ARCH) \
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$(if $(KBUILD_PRESERVE),-p) \
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$(if $(1),-r $(firstword $(wildcard $(@:.symtypes=.symref) /dev/null)))
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quiet_cmd_cc_symtypes_c = SYM $(quiet_modtag) $@
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cmd_cc_symtypes_c = \
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set -e; \
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$(call cmd_genksyms, true) >/dev/null; \
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test -s $@ || rm -f $@
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$(obj)/%.symtypes : $(src)/%.c FORCE
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$(call cmd,cc_symtypes_c)
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# C (.c) files
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# The C file is compiled and updated dependency information is generated.
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# (See cmd_cc_o_c + relevant part of rule_cc_o_c)
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quiet_cmd_cc_o_c = CC $(quiet_modtag) $@
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ifndef CONFIG_MODVERSIONS
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cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
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else
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# When module versioning is enabled the following steps are executed:
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# o compile a .tmp_<file>.s from <file>.c
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# o if .tmp_<file>.s doesn't contain a __ksymtab version, i.e. does
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# not export symbols, we just assemble .tmp_<file>.s to <file>.o and
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# are done.
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# o otherwise, we calculate symbol versions using the good old
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# genksyms on the preprocessed source and postprocess them in a way
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# that they are usable as assembly source
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# o assemble <file>.o from .tmp_<file>.s forcing inclusion of directives
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# defining the actual values of __crc_*, followed by objcopy-ing them
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# to force these symbols to be local to permit stripping them later.
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s_file = $(@D)/.tmp_$(@F:.o=.s)
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v_file = $(@D)/.tmp_$(@F:.o=.v)
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tmp_o_file = $(@D)/.tmp_$(@F)
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no_g_c_flags = $(filter-out -g%,$(c_flags))
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cmd_cc_o_c = $(CC) $(c_flags) -S -o $(s_file) $<
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cmd_modversions = \
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if grep -q __ksymtab $(s_file); then \
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if $(call cmd_genksyms, $(KBUILD_SYMTYPES)) > $(v_file) \
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&& $(CC) $(no_g_c_flags) -c -Wa,$(v_file) \
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-o $(tmp_o_file) $(s_file) \
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&& $(OBJCOPY) -L '__crc_*' -L '___crc_*' -w \
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$(tmp_o_file) $@; \
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then \
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: ; \
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else \
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rm -f $@; exit 1; \
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fi; \
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else \
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rm -f $(v_file); \
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$(CC) $(no_g_c_flags) -c -o $@ $(s_file); \
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fi;
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endif
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ifdef CONFIG_64BIT
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arch_bits = 64
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else
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arch_bits = 32
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endif
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ifdef CONFIG_FTRACE_MCOUNT_RECORD
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cmd_record_mcount = perl $(srctree)/scripts/recordmcount.pl \
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"$(ARCH)" "$(arch_bits)" "$(OBJDUMP)" "$(OBJCOPY)" "$(CC)" "$(LD)" \
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"$(NM)" "$(RM)" "$(MV)" "$(@)";
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endif
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define rule_cc_o_c
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$(call echo-cmd,checksrc) $(cmd_checksrc) \
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$(call echo-cmd,cc_o_c) $(cmd_cc_o_c); \
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$(cmd_modversions) \
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$(cmd_record_mcount) \
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scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' > \
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$(dot-target).tmp; \
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if [ -r $(@D)/.tmp_$(@F:.o=.v) ]; then \
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echo >> $(dot-target).tmp; \
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echo '$@: $(GENKSYMS)' >> $(dot-target).tmp; \
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echo '$(GENKSYMS):: ;' >> $(dot-target).tmp; \
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fi; \
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rm -f $(depfile) $(@D)/.tmp_$(@F:.o=.?); \
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mv -f $(dot-target).tmp $(dot-target).cmd
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endef
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# Built-in and composite module parts
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$(obj)/%.o: $(src)/%.c FORCE
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$(call cmd,force_checksrc)
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$(call if_changed_rule,cc_o_c)
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# Single-part modules are special since we need to mark them in $(MODVERDIR)
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$(single-used-m): $(obj)/%.o: $(src)/%.c FORCE
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$(call cmd,force_checksrc)
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$(call if_changed_rule,cc_o_c)
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@{ echo $(@:.o=.ko); echo $@; } > $(MODVERDIR)/$(@F:.o=.mod)
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quiet_cmd_cc_lst_c = MKLST $@
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cmd_cc_lst_c = $(CC) $(c_flags) -g -c -o $*.o $< && \
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$(CONFIG_SHELL) $(srctree)/scripts/makelst $*.o \
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System.map $(OBJDUMP) > $@
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$(obj)/%.lst: $(src)/%.c FORCE
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$(call if_changed_dep,cc_lst_c)
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# Compile assembler sources (.S)
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# ---------------------------------------------------------------------------
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modkern_aflags := $(AFLAGS_KERNEL)
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$(real-objs-m) : modkern_aflags := $(AFLAGS_MODULE)
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$(real-objs-m:.o=.s): modkern_aflags := $(AFLAGS_MODULE)
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quiet_cmd_as_s_S = CPP $(quiet_modtag) $@
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cmd_as_s_S = $(CPP) $(a_flags) -o $@ $<
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$(obj)/%.s: $(src)/%.S FORCE
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$(call if_changed_dep,as_s_S)
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quiet_cmd_as_o_S = AS $(quiet_modtag) $@
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cmd_as_o_S = $(CC) $(a_flags) -c -o $@ $<
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$(obj)/%.o: $(src)/%.S FORCE
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$(call if_changed_dep,as_o_S)
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targets += $(real-objs-y) $(real-objs-m) $(lib-y)
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targets += $(extra-y) $(MAKECMDGOALS) $(always)
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# Linker scripts preprocessor (.lds.S -> .lds)
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# ---------------------------------------------------------------------------
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quiet_cmd_cpp_lds_S = LDS $@
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cmd_cpp_lds_S = $(CPP) $(cpp_flags) -D__ASSEMBLY__ -o $@ $<
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$(obj)/%.lds: $(src)/%.lds.S FORCE
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$(call if_changed_dep,cpp_lds_S)
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# Build the compiled-in targets
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# ---------------------------------------------------------------------------
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# To build objects in subdirs, we need to descend into the directories
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$(sort $(subdir-obj-y)): $(subdir-ym) ;
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#
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# Rule to compile a set of .o files into one .o file
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#
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ifdef builtin-target
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quiet_cmd_link_o_target = LD $@
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# If the list of objects to link is empty, just create an empty built-in.o
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cmd_link_o_target = $(if $(strip $(obj-y)),\
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$(LD) $(ld_flags) -r -o $@ $(filter $(obj-y), $^) \
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$(cmd_secanalysis),\
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rm -f $@; $(AR) rcs $@)
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$(builtin-target): $(obj-y) FORCE
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$(call if_changed,link_o_target)
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targets += $(builtin-target)
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endif # builtin-target
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#
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# Rule to create modules.order file
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#
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# Create commands to either record .ko file or cat modules.order from
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# a subdirectory
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modorder-cmds = \
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$(foreach m, $(modorder), \
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$(if $(filter %/modules.order, $m), \
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cat $m;, echo kernel/$m;))
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$(modorder-target): $(subdir-ym) FORCE
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$(Q)(cat /dev/null; $(modorder-cmds)) > $@
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#
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# Rule to compile a set of .o files into one .a file
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#
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ifdef lib-target
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quiet_cmd_link_l_target = AR $@
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cmd_link_l_target = rm -f $@; $(AR) rcs $@ $(lib-y)
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$(lib-target): $(lib-y) FORCE
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$(call if_changed,link_l_target)
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targets += $(lib-target)
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endif
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#
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# Rule to link composite objects
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#
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# Composite objects are specified in kbuild makefile as follows:
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# <composite-object>-objs := <list of .o files>
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# or
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# <composite-object>-y := <list of .o files>
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link_multi_deps = \
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$(filter $(addprefix $(obj)/, \
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$($(subst $(obj)/,,$(@:.o=-objs))) \
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$($(subst $(obj)/,,$(@:.o=-y)))), $^)
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quiet_cmd_link_multi-y = LD $@
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cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
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quiet_cmd_link_multi-m = LD [M] $@
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cmd_link_multi-m = $(cmd_link_multi-y)
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# We would rather have a list of rules like
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# foo.o: $(foo-objs)
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# but that's not so easy, so we rather make all composite objects depend
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# on the set of all their parts
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$(multi-used-y) : %.o: $(multi-objs-y) FORCE
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$(call if_changed,link_multi-y)
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$(multi-used-m) : %.o: $(multi-objs-m) FORCE
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$(call if_changed,link_multi-m)
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@{ echo $(@:.o=.ko); echo $(link_multi_deps); } > $(MODVERDIR)/$(@F:.o=.mod)
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targets += $(multi-used-y) $(multi-used-m)
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# Descending
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# ---------------------------------------------------------------------------
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PHONY += $(subdir-ym)
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$(subdir-ym):
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$(Q)$(MAKE) $(build)=$@
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# Add FORCE to the prequisites of a target to force it to be always rebuilt.
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# ---------------------------------------------------------------------------
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PHONY += FORCE
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FORCE:
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# Read all saved command lines and dependencies for the $(targets) we
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# may be building above, using $(if_changed{,_dep}). As an
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# optimization, we don't need to read them if the target does not
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# exist, we will rebuild anyway in that case.
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targets := $(wildcard $(sort $(targets)))
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cmd_files := $(wildcard $(foreach f,$(targets),$(dir $(f)).$(notdir $(f)).cmd))
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ifneq ($(cmd_files),)
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include $(cmd_files)
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endif
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# Declare the contents of the .PHONY variable as phony. We keep that
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# information in a variable se we can use it in if_changed and friends.
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.PHONY: $(PHONY)
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