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Commit 1f2bfbd0 authored by Sam Ravnborg's avatar Sam Ravnborg Committed by Michal Marek
Browse files

kbuild: link of vmlinux moved to a script 



Move the final link of vmlinux to a script to improve
readability and maintainability of the code.

The Makefile fragments used to link vmlinux has over the
years seen far too many changes and the logic had become
hard to follow.

As the process by nature is serialized there was
nothing gained including this in the Makefile.

"um" has special link requirments - and the
only way to handle this was to hard-code the linking
of "um" in the script.
This was better than trying to modularize it only for the
benefit of "um" anyway.

The shell script has been improved after input from:
Arnaud Lacombe <lacombar@gmail.com>
Nick Bowler <nbowler@elliptictech.com>

Signed-off-by: default avatarSam Ravnborg <sam@ravnborg.org>
Cc: Arnaud Lacombe <lacombar@gmail.com>
Cc: Nick Bowler <nbowler@elliptictech.com>
Cc: Richard Weinberger <richard@nod.at>
Signed-off-by: default avatarMichal Marek <mmarek@suse.cz>
parent 95698570

Makefile

+12 −203
Original line number Diff line number Diff line
@@ -337,7 +337,6 @@ AWK = awk 
GENKSYMS	= scripts/genksyms/genksyms

INSTALLKERNEL  := installkernel

DEPMOD		= /sbin/depmod

KALLSYMS	= scripts/kallsyms

PERL		= perl

CHECK		= sparse
@@ -723,191 +722,21 @@ libs-y1 := $(patsubst %/, %/lib.a, $(libs-y)) 
libs-y2		:= $(patsubst %/, %/built-in.o, $(libs-y))

libs-y		:= $(libs-y1) $(libs-y2)



# externally visible symbols

# Externally visible symbols (used by link-vmlinux.sh)

export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)

export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y) $(drivers-y) $(net-y)

export KBUILD_LDS          := arch/$(SRCARCH)/kernel/vmlinux.lds

export LDFLAGS_vmlinux



# Build vmlinux

# ---------------------------------------------------------------------------

# vmlinux is built from the objects selected by $(vmlinux-init) and

# $(vmlinux-main). Most are built-in.o files from top-level directories

# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.

# Ordering when linking is important, and $(vmlinux-init) must be first.

#

# vmlinux

#   ^

#   |

#   +-< $(vmlinux-init)

#   |   +--< init/version.o + more

#   |

#   +--< $(vmlinux-main)

#   |    +--< driver/built-in.o mm/built-in.o + more

#   |

#   +-< kallsyms.o (see description in CONFIG_KALLSYMS section)

#

# vmlinux version (uname -v) cannot be updated during normal

# descending-into-subdirs phase since we do not yet know if we need to

# update vmlinux.

# Therefore this step is delayed until just before final link of vmlinux -

# except in the kallsyms case where it is done just before adding the

# symbols to the kernel.

#

# System.map is generated to document addresses of all kernel symbols



vmlinux-init := $(head-y) $(init-y)

vmlinux-main := $(core-y) $(libs-y) $(drivers-y) $(net-y)

vmlinux-all  := $(vmlinux-init) $(vmlinux-main)

vmlinux-lds  := arch/$(SRCARCH)/kernel/vmlinux.lds



# Rule to link vmlinux - also used during CONFIG_KALLSYMS

# May be overridden by arch/$(ARCH)/Makefile

quiet_cmd_vmlinux__ ?= LD      $@

      cmd_vmlinux__ ?= $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) -o $@ \

      -T $(vmlinux-lds) $(vmlinux-init)                          \

      --start-group $(vmlinux-main) --end-group                  \

      $(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o FORCE ,$^)



# Generate new vmlinux version

quiet_cmd_vmlinux_version = GEN     .version

      cmd_vmlinux_version = set -e;                     \

	if [ ! -r .version ]; then			\

	  rm -f .version;				\

	  echo 1 >.version;				\

	else						\

	  mv .version .old_version;			\

	  expr 0$$(cat .old_version) + 1 >.version;	\

	fi;						\

	$(MAKE) $(build)=init



# Generate System.map

quiet_cmd_sysmap = SYSMAP

      cmd_sysmap = $(CONFIG_SHELL) $(srctree)/scripts/mksysmap



# Link of vmlinux

# If CONFIG_KALLSYMS is set .version is already updated

# Generate System.map and verify that the content is consistent

# Use + in front of the vmlinux_version rule to silent warning with make -j2

# First command is ':' to allow us to use + in front of the rule

define rule_vmlinux__

	:

	$(if $(CONFIG_KALLSYMS),,+$(call cmd,vmlinux_version))



	$(call cmd,vmlinux__)

	$(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd



	$(Q)$(if $($(quiet)cmd_sysmap),                                      \

	  echo '  $($(quiet)cmd_sysmap)  System.map' &&)                     \

	$(cmd_sysmap) $@ System.map;                                         \

	if [ $$? -ne 0 ]; then                                               \

		rm -f $@;                                                    \

		/bin/false;                                                  \

	fi;

	$(verify_kallsyms)

endef





ifdef CONFIG_KALLSYMS

# Generate section listing all symbols and add it into vmlinux $(kallsyms.o)

# It's a three stage process:

# o .tmp_vmlinux1 has all symbols and sections, but __kallsyms is

#   empty

#   Running kallsyms on that gives us .tmp_kallsyms1.o with

#   the right size - vmlinux version (uname -v) is updated during this step

# o .tmp_vmlinux2 now has a __kallsyms section of the right size,

#   but due to the added section, some addresses have shifted.

#   From here, we generate a correct .tmp_kallsyms2.o

# o The correct .tmp_kallsyms2.o is linked into the final vmlinux.

# o Verify that the System.map from vmlinux matches the map from

#   .tmp_vmlinux2, just in case we did not generate kallsyms correctly.

# o If 'make KALLSYMS_EXTRA_PASS=1" was used, do an extra pass using

#   .tmp_vmlinux3 and .tmp_kallsyms3.o.  This is only meant as a

#   temporary bypass to allow the kernel to be built while the

#   maintainers work out what went wrong with kallsyms.



last_kallsyms := 2



ifdef KALLSYMS_EXTRA_PASS

ifneq ($(KALLSYMS_EXTRA_PASS),0)

last_kallsyms := 3

endif

endif



kallsyms.o := .tmp_kallsyms$(last_kallsyms).o



define verify_kallsyms

	$(Q)$(if $($(quiet)cmd_sysmap),                                      \

	  echo '  $($(quiet)cmd_sysmap)  .tmp_System.map' &&)                \

	  $(cmd_sysmap) .tmp_vmlinux$(last_kallsyms) .tmp_System.map

	$(Q)cmp -s System.map .tmp_System.map ||                             \

		(echo Inconsistent kallsyms data;                            \

		 echo This is a bug - please report about it;                \

		 echo Try "make KALLSYMS_EXTRA_PASS=1" as a workaround;      \

		 rm .tmp_kallsyms* ; /bin/false )

endef



# Update vmlinux version before link

# Use + in front of this rule to silent warning about make -j1

# First command is ':' to allow us to use + in front of this rule

cmd_ksym_ld = $(cmd_vmlinux__)

define rule_ksym_ld

	: 

	+$(call cmd,vmlinux_version)

	$(call cmd,vmlinux__)

	$(Q)echo 'cmd_$@ := $(cmd_vmlinux__)' > $(@D)/.$(@F).cmd

endef



# Generate .S file with all kernel symbols

quiet_cmd_kallsyms = KSYM    $@

      cmd_kallsyms = $(NM) -n $< | $(KALLSYMS) \

                     $(if $(CONFIG_KALLSYMS_ALL),--all-symbols) > $@

vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)



.tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms3.o: %.o: %.S scripts FORCE

	$(call if_changed_dep,as_o_S)

# Final link of vmlinux

      cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux)

quiet_cmd_link-vmlinux = LINK    $@



.tmp_kallsyms%.S: .tmp_vmlinux% $(KALLSYMS)

	$(call cmd,kallsyms)



# .tmp_vmlinux1 must be complete except kallsyms, so update vmlinux version

.tmp_vmlinux1: $(vmlinux-lds) $(vmlinux-all) FORCE

	$(call if_changed_rule,ksym_ld)



.tmp_vmlinux2: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms1.o FORCE

	$(call if_changed,vmlinux__)



.tmp_vmlinux3: $(vmlinux-lds) $(vmlinux-all) .tmp_kallsyms2.o FORCE

	$(call if_changed,vmlinux__)



# Needs to visit scripts/ before $(KALLSYMS) can be used.

$(KALLSYMS): scripts ;



# Generate some data for debugging strange kallsyms problems

debug_kallsyms: .tmp_map$(last_kallsyms)



.tmp_map%: .tmp_vmlinux% FORCE

	($(OBJDUMP) -h $< | $(AWK) '/^ +[0-9]/{print $$4 " 0 " $$2}'; $(NM) $<) | sort > $@



.tmp_map3: .tmp_map2



.tmp_map2: .tmp_map1



endif # ifdef CONFIG_KALLSYMS



# Do modpost on a prelinked vmlinux. The finally linked vmlinux has

# relevant sections renamed as per the linker script.

quiet_cmd_vmlinux-modpost = LD      $@

      cmd_vmlinux-modpost = $(LD) $(LDFLAGS) -r -o $@                          \

	 $(vmlinux-init) --start-group $(vmlinux-main) --end-group             \

	 $(filter-out $(vmlinux-init) $(vmlinux-main) FORCE ,$^)

define rule_vmlinux-modpost

	:

	+$(call cmd,vmlinux-modpost)

	$(Q)$(MAKE) -f $(srctree)/scripts/Makefile.modpost $@

	$(Q)echo 'cmd_$@ := $(cmd_vmlinux-modpost)' > $(dot-target).cmd

endef



# vmlinux image - including updated kernel symbols

vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o $(kallsyms.o) FORCE

# Include targets which we want to

# execute if the rest of the kernel build went well.

vmlinux: scripts/link-vmlinux.sh $(vmlinux-deps) FORCE

ifdef CONFIG_HEADERS_CHECK

	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check

endif
@@ -917,22 +746,11 @@ endif 
ifdef CONFIG_BUILD_DOCSRC

	$(Q)$(MAKE) $(build)=Documentation

endif

	$(call vmlinux-modpost)

	$(call if_changed_rule,vmlinux__)

	$(Q)rm -f .old_version



# build vmlinux.o first to catch section mismatch errors early

ifdef CONFIG_KALLSYMS

.tmp_vmlinux1: vmlinux.o

endif



modpost-init := $(filter-out init/built-in.o, $(vmlinux-init))

vmlinux.o: $(modpost-init) $(vmlinux-main) FORCE

	$(call if_changed_rule,vmlinux-modpost)

	+$(call if_changed,link-vmlinux)



# The actual objects are generated when descending, 

# make sure no implicit rule kicks in

$(sort $(vmlinux-init) $(vmlinux-main)) $(vmlinux-lds): $(vmlinux-dirs) ;

$(sort $(vmlinux-deps)): $(vmlinux-dirs) ;



# Handle descending into subdirectories listed in $(vmlinux-dirs)

# Preset locale variables to speed up the build process. Limit locale
@@ -1156,8 +974,6 @@ endif # CONFIG_MODULES 


# Directories & files removed with 'make clean'

CLEAN_DIRS  += $(MODVERDIR)

CLEAN_FILES +=	vmlinux System.map \

                .tmp_kallsyms* .tmp_version .tmp_vmlinux* .tmp_System.map



# Directories & files removed with 'make mrproper'

MRPROPER_DIRS  += include/config usr/include include/generated          \
@@ -1403,6 +1219,7 @@ scripts: ; 
endif # KBUILD_EXTMOD



clean: $(clean-dirs)

	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh clean

	$(call cmd,rmdirs)

	$(call cmd,rmfiles)

	@find $(if $(KBUILD_EXTMOD), $(KBUILD_EXTMOD), .) $(RCS_FIND_IGNORE) \
@@ -1536,14 +1353,6 @@ quiet_cmd_depmod = DEPMOD $(KERNELRELEASE) 
cmd_crmodverdir = $(Q)mkdir -p $(MODVERDIR) \

                  $(if $(KBUILD_MODULES),; rm -f $(MODVERDIR)/*)



a_flags = -Wp,-MD,$(depfile) $(KBUILD_AFLAGS) $(AFLAGS_KERNEL) \

	  $(KBUILD_AFLAGS_KERNEL)                              \

	  $(NOSTDINC_FLAGS) $(LINUXINCLUDE) $(KBUILD_CPPFLAGS) \

	  $(modkern_aflags) $(EXTRA_AFLAGS) $(AFLAGS_$(basetarget).o)



quiet_cmd_as_o_S = AS      $@

cmd_as_o_S       = $(CC) $(a_flags) -c -o $@ $<



# read all saved command lines



targets := $(wildcard $(sort $(targets)))

arch/um/Makefile

+2 −9
Original line number Diff line number Diff line
@@ -121,15 +121,8 @@ LINK_WRAPS = -Wl,--wrap,malloc -Wl,--wrap,free -Wl,--wrap,calloc 


LD_FLAGS_CMDLINE = $(foreach opt,$(LDFLAGS),-Wl,$(opt))



CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE)

define cmd_vmlinux__

	$(CC) $(CFLAGS_vmlinux) -o $@ \

	-Wl,-T,$(vmlinux-lds) $(vmlinux-init) \

	-Wl,--start-group $(vmlinux-main) -Wl,--end-group \

	-lutil \

	$(filter-out $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o \

	FORCE ,$^) ; rm -f linux

endef

# Used by link-vmlinux.sh which has special support for um link

export CFLAGS_vmlinux := $(LINK-y) $(LINK_WRAPS) $(LD_FLAGS_CMDLINE)



# When cleaning we don't include .config, so we don't include

# TT or skas makefiles and don't clean skas_ptregs.h.

scripts/link-vmlinux.sh

0 → 100644
+211 −0
Original line number Diff line number Diff line 
#!/bin/sh

#

# link vmlinux

#

# vmlinux is linked from the objects selected by $(KBUILD_VMLINUX_INIT) and

# $(KBUILD_VMLINUX_MAIN). Most are built-in.o files from top-level directories

# in the kernel tree, others are specified in arch/$(ARCH)/Makefile.

# Ordering when linking is important, and $(KBUILD_VMLINUX_INIT) must be first.

#

# vmlinux

#   ^

#   |

#   +-< $(KBUILD_VMLINUX_INIT)

#   |   +--< init/version.o + more

#   |

#   +--< $(KBUILD_VMLINUX_MAIN)

#   |    +--< drivers/built-in.o mm/built-in.o + more

#   |

#   +-< ${kallsymso} (see description in KALLSYMS section)

#

# vmlinux version (uname -v) cannot be updated during normal

# descending-into-subdirs phase since we do not yet know if we need to

# update vmlinux.

# Therefore this step is delayed until just before final link of vmlinux.

#

# System.map is generated to document addresses of all kernel symbols



# Error out on error

set -e



# Nice output in kbuild format

# Will be supressed by "make -s"

info()

{

	if [ "${quiet}" != "silent_" ]; then

		printf "  %-7s %s\n" ${1} ${2}

	fi

}



# Link of vmlinux.o used for section mismatch analysis

# ${1} output file

modpost_link()

{

	${LD} ${LDFLAGS} -r -o ${1} ${KBUILD_VMLINUX_INIT}                   \

		--start-group ${KBUILD_VMLINUX_MAIN} --end-group

}



# Link of vmlinux

# ${1} - optional extra .o files

# ${2} - output file

vmlinux_link()

{

	local lds="${objtree}/${KBUILD_LDS}"



	if [ "${SRCARCH}" != "um" ]; then

		${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2}                  \

			-T ${lds} ${KBUILD_VMLINUX_INIT}                     \

			--start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}

	else

		${CC} ${CFLAGS_vmlinux} -o ${2}                              \

			-Wl,-T,${lds} ${KBUILD_VMLINUX_INIT}                 \

			-Wl,--start-group                                    \

				 ${KBUILD_VMLINUX_MAIN}                      \

			-Wl,--end-group                                      \

			-lutil ${1}

		rm -f linux

	fi

}





# Create ${2} .o file with all symbols from the ${1} object file

kallsyms()

{

	info KSYM ${2}

	local kallsymopt;



	if [ -n "${CONFIG_KALLSYMS_ALL}" ]; then

		kallsymopt=--all-symbols

	fi



	local aflags="${KBUILD_AFLAGS} ${NOSTDINC_FLAGS}                     \

		      ${LINUXINCLUDE} ${KBUILD_CPPFLAGS}"



	${NM} -n ${1} | \

		scripts/kallsyms ${kallsymopt} | \

		${CC} ${aflags} -c -o ${2} -x assembler-with-cpp -

}



# Create map file with all symbols from ${1}

# See mksymap for additional details

mksysmap()

{

	${CONFIG_SHELL} "${srctree}/scripts/mksysmap" ${1} ${2}

}



# Delete output files in case of error

trap cleanup SIGHUP SIGINT SIGQUIT SIGTERM ERR

cleanup()

{

	rm -f .old_version

	rm -f .tmp_System.map

	rm -f .tmp_kallsyms*

	rm -f .tmp_version

	rm -f .tmp_vmlinux*

	rm -f System.map

	rm -f vmlinux

	rm -f vmlinux.o

}



#

#

# Use "make V=1" to debug this script

case "${KBUILD_VERBOSE}" in

*1*)

	set -x

	;;

esac



if [ "$1" = "clean" ]; then

	cleanup

	exit 0

fi



# We need access to CONFIG_ symbols

. ./.config



#link vmlinux.o

info LD vmlinux.o

modpost_link vmlinux.o



# modpost vmlinux.o to check for section mismatches

${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o



# Update version

info GEN .version

if [ ! -r .version ]; then

	rm -f .version;

	echo 1 >.version;

else

	mv .version .old_version;

	expr 0$(cat .old_version) + 1 >.version;

fi;



# final build of init/

${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init



kallsymso=""

kallsyms_vmlinux=""

if [ -n "${CONFIG_KALLSYMS}" ]; then



	# kallsyms support

	# Generate section listing all symbols and add it into vmlinux

	# It's a three step process:

	# 1)  Link .tmp_vmlinux1 so it has all symbols and sections,

	#     but __kallsyms is empty.

	#     Running kallsyms on that gives us .tmp_kallsyms1.o with

	#     the right size

	# 2)  Link .tmp_vmlinux2 so it now has a __kallsyms section of

	#     the right size, but due to the added section, some

	#     addresses have shifted.

	#     From here, we generate a correct .tmp_kallsyms2.o

	# 2a) We may use an extra pass as this has been necessary to

	#     woraround some alignment related bugs.

	#     KALLSYMS_EXTRA_PASS=1 is used to trigger this.

	# 3)  The correct ${kallsymso} is linked into the final vmlinux.

	#

	# a)  Verify that the System.map from vmlinux matches the map from

	#     ${kallsymso}.



	kallsymso=.tmp_kallsyms2.o

	kallsyms_vmlinux=.tmp_vmlinux2



	# step 1

	vmlinux_link "" .tmp_vmlinux1

	kallsyms .tmp_vmlinux1 .tmp_kallsyms1.o



	# step 2

	vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2

	kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o



	# step 2a

	if [ -n "${KALLSYMS_EXTRA_PASS}" ]; then

		kallsymso=.tmp_kallsyms3.o

		kallsyms_vmlinux=.tmp_vmlinux3



		vmlinux_link .tmp_kallsyms2.o .tmp_vmlinux3



		kallsyms .tmp_vmlinux3 .tmp_kallsyms3.o

	fi

fi



info LD vmlinux

vmlinux_link "${kallsymso}" vmlinux



info SYSMAP System.map

mksysmap vmlinux System.map



# step a (see comment above)

if [ -n "${CONFIG_KALLSYMS}" ]; then

	mksysmap ${kallsyms_vmlinux} .tmp_System.map



	if ! cmp -s System.map .tmp_System.map; then

		echo Inconsistent kallsyms data

		echo echo Try "make KALLSYMS_EXTRA_PASS=1" as a workaround

		cleanup

		exit 1

	fi

fi



# We made a new kernel - delete old version file

rm -f .old_version