Message-ID: <20080604214514.GA13032@uranus.ravnborg.org>
Date:	Wed, 4 Jun 2008 23:45:14 +0200
From:	Sam Ravnborg <sam@...nborg.org>
To:	LKML <linux-kernel@...r.kernel.org>,
	linux-kbuild <linux-kbuild@...r.kernel.org>
Subject: Simplify vmlinux link

Following two patches simplifies the foo used to link
vmlinux to a level where it is maintainable again.

The patches remove the KALLSYMS_EXTRA_PASS stuff and
move the vmlinux link stuff to a small shell script.

This need some testing as I have not even been able
to boot test this as my dev box is down.
So help and feedback is really appreciated.

Full patch below - I will post sepearate patches as follow-up.

Patches will be pushed out to kbuild-next only when I get
some positive reponse that it boots.

	Sam

 Makefile                |  200 +++-------------------------------------------
 init/Kconfig            |   12 ---
 scripts/link-vmlinux.sh |  144 ++++++++++++++++++++++++++++++++++
 scripts/mksysmap        |   45 -----------
 5 files changed, 160 insertions(+), 258 deletions(-)

diff --git a/Makefile b/Makefile
index 8db70fe..a958d34 100644
--- a/Makefile
+++ b/Makefile
@@ -626,206 +626,32 @@ libs-y1		:= $(patsubst %/, %/lib.a, $(libs-y))
 libs-y2		:= $(patsubst %/, %/built-in.o, $(libs-y))
 libs-y		:= $(libs-y1) $(libs-y2)
 
-# 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.
+# Build vmlinux
 #
-# 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
-export KBUILD_VMLINUX_OBJS := $(vmlinux-all)
-
-# Rule to link vmlinux - also used during CONFIG_KALLSYMS
-# May be overridden by arch/$(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 $(kallsyms.o)
-# It's a three stage process:
-# o .tmp_vmlinux1 has all symbols and sections, but __kallsyms is
-#   empty
-#   Running kallsyms on that gives us .tmp_kallsyms1.o with
-#   the right size - vmlinux version (uname -v) is updated during this step
-# o .tmp_vmlinux2 now has a __kallsyms section of the right size,
-#   but due to the added section, some addresses have shifted.
-#   From here, we generate a correct .tmp_kallsyms2.o
-# o The correct .tmp_kallsyms2.o is linked into the final vmlinux.
-# o Verify that the System.map from vmlinux matches the map from
-#   .tmp_vmlinux2, just in case we did not generate kallsyms correctly.
-# o If CONFIG_KALLSYMS_EXTRA_PASS is set, do an extra pass using
-#   .tmp_vmlinux3 and .tmp_kallsyms3.o.  This is only meant as a
-#   temporary bypass to allow the kernel to be built while the
-#   maintainers work out what went wrong with kallsyms.
-
-ifdef CONFIG_KALLSYMS_EXTRA_PASS
-last_kallsyms := 3
-else
-last_kallsyms := 2
-endif
-
-kallsyms.o := .tmp_kallsyms$(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 Try setting CONFIG_KALLSYMS_EXTRA_PASS;                \
-		 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)
-
-.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
+# ---------------------------------------------------------------------------
+export KBUILD_VMLINUX_INIT := $(head-y) $(init-y)
+export KBUILD_VMLINUX_MAIN := $(core-y) $(libs-y) $(drivers-y) $(net-y)
+export KBUILD_VMLINUX_LDS  := arch/$(SRCARCH)/kernel/vmlinux.lds
+export KBUILD_VMLINUX_EXTRA
+export LDFLAGS_vmlinux
 
-# 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-deps := $(KBUILD_VMLINUX_INIT) $(KBUILD_VMLINUX_MAIN)
+vmlinux-deps += $(KBUILD_VMLINUX_LDS)
 
 # vmlinux image - including updated kernel symbols
-vmlinux: $(vmlinux-lds) $(vmlinux-init) $(vmlinux-main) vmlinux.o $(kallsyms.o) FORCE
+vmlinux: $(vmlinux-deps)
 ifdef CONFIG_HEADERS_CHECK
 	$(Q)$(MAKE) -f $(srctree)/Makefile headers_check
 endif
 ifdef CONFIG_SAMPLES
 	$(Q)$(MAKE) $(build)=samples
 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)
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/link-vmlinux.sh
 
-# The actual objects are generated when descending, 
+# 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
diff --git a/init/Kconfig b/init/Kconfig
index 6199d11..5fc1067 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -588,18 +588,6 @@ config KALLSYMS_ALL
 
 	   Say N.
 
-config KALLSYMS_EXTRA_PASS
-	bool "Do an extra kallsyms pass"
-	depends on KALLSYMS
-	help
-	   If kallsyms is not working correctly, the build will fail with
-	   inconsistent kallsyms data.  If that occurs, log a bug report and
-	   turn on KALLSYMS_EXTRA_PASS which should result in a stable build.
-	   Always say N here unless you find a bug in kallsyms, which must be
-	   reported.  KALLSYMS_EXTRA_PASS is only a temporary workaround while
-	   you wait for kallsyms to be fixed.
-
-
 config HOTPLUG
 	bool "Support for hot-pluggable devices" if EMBEDDED
 	default y
diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
new file mode 100644
index 0000000..224f698
--- /dev/null
+++ b/scripts/link-vmlinux.sh
@@ -0,0 +1,144 @@
+# Build vmlinux
+# ---------------------------------------------------------------------------
+# vmlinux is built 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)
+#   |    +--< driver/built-in.o mm/built-in.o + more
+#   |
+#   +-< $(KBUILD_VMLINUX_EXTRA)
+#
+# vmlinux version (uname -v) cannot be updated during normal
+# descending-into-subdirs phase since we do not yet know if we need to
+# update vmlinux.
+#
+# System.map is generated to document addresses of all kernel symbols
+
+MAKE=make
+
+# We need access to CONFIG_ symbols
+source .config
+# Error out on error
+set -e
+# USe "make V=3" to debug this script
+if [ "${KBUILD_VERBOSE}" = "3" ]; then
+	set -x
+fi
+# Override MAKEFLAGS to avoid parrallel builds
+MAKEFLAGS='--no-print-directory -Rr'
+# Delete output files in case of error
+trap cleanup SIGHUP SIGINT SIGQUIT SIGTERM ERR
+cleanup()
+{
+	rm -f vmlinux.o
+	rm -f .old_version
+	rm -f .tmp_vmlinux*
+	rm -f .tmp_kallsyms*
+	rm -f vmlinux
+	rm -f .tmp_System.map
+	rm -f System.map
+}
+# non-verbose output
+tell()
+{
+	printf "  %-7s %s\n" $1 $2
+}
+
+#####
+# Generate System.map
+
+# $NM produces the following output:
+# f0081e80 T alloc_vfsmnt
+
+#   The second row specify the type of the symbol:
+#   A = Absolute
+#   B = Uninitialised data (.bss)
+#   C = Comon symbol
+#   D = Initialised data
+#   G = Initialised data for small objects
+#   I = Indirect reference to another symbol
+#   N = Debugging symbol
+#   R = Read only
+#   S = Uninitialised data for small objects
+#   T = Text code symbol
+#   U = Undefined symbol
+#   V = Weak symbol
+#   W = Weak symbol
+#   Corresponding small letters are local symbols
+
+# For System.map filter away:
+#   a - local absolute symbols
+#   N = Debugging symbol
+#   U - undefined global symbols
+#   w - local weak symbols
+
+# readprofile starts reading symbols when _stext is found, and
+# continue until it finds a symbol which is not either of 'T', 't',
+# 'W' or 'w'. __crc_ are 'A' and placed in the middle
+# so we just ignore them to let readprofile continue to work.
+# (At least sparc64 has __crc_ in the middle).
+mksysmap()
+{
+	$NM -n $1 | grep -v '\( [aNUw] \)\|\(__crc_\)\|\( \$[adt]\)'
+}
+
+# link vmlinux.o
+tell LD vmlinux.o
+${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -r -o vmlinux.o      \
+	${KBUILD_VMLINUX_INIT}                           \
+        --start-group ${KBUILD_VMLINUX_MAIN} --end-group \
+	${KBUILD_VMLINUX_EXTRA}
+
+# modpost vmlinux.o
+${MAKE} -f ${srctree}/scripts/Makefile.modpost vmlinux.o
+
+# Update version
+tell GEN .version
+if [ ! -r .version ]; then
+	rm -f .version;
+	echo 1 >.version;
+else
+	mv .version .old_version;
+	expr 0$(cat .old_version) + 1 >.version;
+fi;
+
+# final build of init/
+${MAKE} -f ${srctree}/scripts/Makefile.build obj=init
+
+VMLINUX=vmlinux
+if [ "${CONFIG_KALLSYMS}" = "y" ]; then
+	VMLINUX=.tmp_vmlinux
+fi
+
+# First stage of fully linked vmlinux
+tell LD ${VMLINUX}
+${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${VMLINUX} \
+      -T ${KBUILD_VMLINUX_LDS} vmlinux.o
+
+if [ "${CONFIG_KALLSYMS}" = "y" ]; then
+
+	# Do an extra pass to link in kallsyms data
+	${NM} -n .tmp_vmlinux | scripts/kallsyms > .tmp_kallsyms.S
+        ${CC} ${KBUILD_AFLAGS} ${KBUILD_CPPFLAGS} -c -o .tmp_kallsyms.o \
+	      .tmp_kallsyms.S
+        # link in kalll symbols
+	tell LD vmlinux
+        ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o vmlinux \
+         -T ${KBUILD_VMLINUX_LDS} vmlinux.o .tmp_kallsyms.o
+fi
+
+tell SYSMAP System.map
+mksysmap vmlinux > System.map
+
+# We made a new kernel - delete old version file
+rm -f .old_version
+
+
diff --git a/scripts/mksysmap b/scripts/mksysmap
deleted file mode 100644
index 6e133a0..0000000
--- a/scripts/mksysmap
+++ /dev/null
@@ -1,45 +0,0 @@
-#!/bin/sh -x
-# Based on the vmlinux file create the System.map file
-# System.map is used by module-init tools and some debugging
-# tools to retrieve the actual addresses of symbols in the kernel.
-#
-# Usage
-# mksysmap vmlinux System.map
-
-
-#####
-# Generate System.map (actual filename passed as second argument)
-
-# $NM produces the following output:
-# f0081e80 T alloc_vfsmnt
-
-#   The second row specify the type of the symbol:
-#   A = Absolute
-#   B = Uninitialised data (.bss)
-#   C = Comon symbol
-#   D = Initialised data
-#   G = Initialised data for small objects
-#   I = Indirect reference to another symbol
-#   N = Debugging symbol
-#   R = Read only
-#   S = Uninitialised data for small objects
-#   T = Text code symbol
-#   U = Undefined symbol
-#   V = Weak symbol
-#   W = Weak symbol
-#   Corresponding small letters are local symbols
-
-# For System.map filter away:
-#   a - local absolute symbols
-#   U - undefined global symbols
-#   N - debugging symbols
-#   w - local weak symbols
-
-# readprofile starts reading symbols when _stext is found, and
-# continue until it finds a symbol which is not either of 'T', 't',
-# 'W' or 'w'. __crc_ are 'A' and placed in the middle
-# so we just ignore them to let readprofile continue to work.
-# (At least sparc64 has __crc_ in the middle).
-
-$NM -n $1 | grep -v '\( [aNUw] \)\|\(__crc_\)\|\( \$[adt]\)' > $2
-
--
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