From linux-kbuild Thu Sep 06 20:43:27 2012 From: James Hogan Date: Thu, 06 Sep 2012 20:43:27 +0000 To: linux-kbuild Subject: Re: [PATCH 3/4] kbuild: link of vmlinux moved to a script Message-Id: <20120906204327.GA4785 () balrog ! le ! imgtec ! org> X-MARC-Message: https://marc.info/?l=linux-kbuild&m=134696426118978 Hi Sam, On Sat, Apr 28, 2012 at 10:59:19PM +0200, Sam Ravnborg wrote: > From c92ef0a63bb191fb7642e744e8c5865a983713fa Mon Sep 17 00:00:00 2001 > From: Sam Ravnborg > Date: Sat, 28 Apr 2012 20:03:59 +0200 > Subject: [PATCH 3/4] 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 Makefil fragments used to link vmlinux has over the > years seen far too much changes and the logic was very > hard to follow. Unfortunately this doesn't appear to take into account that some architectures add arguments to the KALLSYMS Makefile variable in their own Makefiles. For example arch/blackfin/Makefile contains the line: KALLSYMS += --symbol-prefix=_ The script doesn't include this when it calls ./scripts/kallsyms and as a result kallsyms_addresses won't correctly override the weak symbol _kallsyms_addresses on such architectures, and it'll hit the BUG_ONs in kernel/kallsyms.c when kallsyms is used, e.g. to print a backtrace: BUG_ON(!kallsyms_addresses); Any thoughts about what the preferred solution would be? There is a Kconfig variable CONFIG_SYMBOL_PREFIX which it may be more convenient to use rather than relying on the architecture's Makefile to adjust the KALLSYMS command. Cheers James > > As the process by nature is serialized there was > nothing gained including this in the Makefile. > > "um" has special link requirments - and the > only was 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 > Nick Bowler > > Signed-off-by: Sam Ravnborg > Cc: Arnaud Lacombe > Cc: Nick Bowler > Cc: Richard Weinberger > --- > Makefile | 215 +++-------------------------------------------- > arch/um/Makefile | 11 +-- > scripts/link-vmlinux.sh | 211 ++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 225 insertions(+), 212 deletions(-) > create mode 100644 scripts/link-vmlinux.sh > > diff --git a/Makefile b/Makefile > index 00bf5b1..e196ec3 100644 > --- a/Makefile > +++ b/Makefile > @@ -341,7 +341,6 @@ AWK = awk > GENKSYMS = scripts/genksyms/genksyms > INSTALLKERNEL := installkernel > DEPMOD = /sbin/depmod > -KALLSYMS = scripts/kallsyms > PERL = perl > CHECK = sparse > > @@ -727,191 +726,21 @@ 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) > $@ > - > -.tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms3.o: %.o: %.S scripts FORCE > - $(call if_changed_dep,as_o_S) > +vmlinux-deps := $(KBUILD_LDS) $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN) > > -.tmp_kallsyms%.S: .tmp_vmlinux% $(KALLSYMS) > - $(call cmd,kallsyms) > +# Final link of vmlinux > + cmd_link-vmlinux = $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) > +quiet_cmd_link-vmlinux = LINK $@ > > -# .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 > @@ -921,22 +750,11 @@ 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 > @@ -1160,8 +978,6 @@ 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 \ > @@ -1407,6 +1223,7 @@ 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) \ > @@ -1540,14 +1357,6 @@ 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))) > diff --git a/arch/um/Makefile b/arch/um/Makefile > index 55c0661..0970910 100644 > --- a/arch/um/Makefile > +++ b/arch/um/Makefile > @@ -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. > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > new file mode 100644 > index 0000000..fb6d058 > --- /dev/null > +++ b/scripts/link-vmlinux.sh > @@ -0,0 +1,211 @@ > +#!/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_vmlinux2 > + > + 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 > -- > 1.7.10 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-arch" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html