From 2df8220cc511326508ec4da2f43ef69311bdd7b9 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 28 Aug 2022 11:39:53 +0900 Subject: [PATCH] kbuild: build init/built-in.a just once Kbuild builds init/built-in.a twice; first during the ordinary directory descending, second from scripts/link-vmlinux.sh. We do this because UTS_VERSION contains the build version and the timestamp. We cannot update it during the normal directory traversal since we do not yet know if we need to update vmlinux. UTS_VERSION is temporarily calculated, but omitted from the update check. Otherwise, vmlinux would be rebuilt every time. When Kbuild results in running link-vmlinux.sh, it increments the version number in the .version file and takes the timestamp at that time to really fix UTS_VERSION. However, updating the same file twice is a footgun. To avoid nasty timestamp issues, all build artifacts that depend on init/built-in.a are atomically generated in link-vmlinux.sh, where some of them do not need rebuilding. To fix this issue, this commit changes as follows: [1] Split UTS_VERSION out to include/generated/utsversion.h from include/generated/compile.h include/generated/utsversion.h is generated just before the vmlinux link. It is generated under include/generated/ because some decompressors (s390, x86) use UTS_VERSION. [2] Split init_uts_ns and linux_banner out to init/version-timestamp.c from init/version.c init_uts_ns and linux_banner contain UTS_VERSION. During the ordinary directory descending, they are compiled with __weak and used to determine if vmlinux needs relinking. Just before the vmlinux link, they are compiled without __weak to embed the real version and timestamp. Signed-off-by: Masahiro Yamada --- arch/powerpc/boot/wrapper | 2 +- arch/s390/boot/version.c | 1 + arch/x86/boot/compressed/kaslr.c | 1 + arch/x86/boot/version.c | 1 + init/.gitignore | 2 + init/Makefile | 55 +++++++++++++++----- init/build-version | 10 ++++ init/version-timestamp.c | 31 +++++++++++ init/version.c | 36 +++++-------- kernel/gen_kheaders.sh | 6 +-- scripts/link-vmlinux.sh | 17 ++---- scripts/mkcompile_h | 89 ++++---------------------------- 12 files changed, 120 insertions(+), 131 deletions(-) create mode 100644 init/.gitignore create mode 100755 init/build-version create mode 100644 init/version-timestamp.c diff --git a/arch/powerpc/boot/wrapper b/arch/powerpc/boot/wrapper index 55978f32fa77..5bdd4dd20bbb 100755 --- a/arch/powerpc/boot/wrapper +++ b/arch/powerpc/boot/wrapper @@ -433,7 +433,7 @@ fi # Extract kernel version information, some platforms want to include # it in the image header version=`${CROSS}strings "$kernel" | grep '^Linux version [-0-9.]' | \ - cut -d' ' -f3` + head -n1 | cut -d' ' -f3` if [ -n "$version" ]; then uboot_version="-n Linux-$version" fi diff --git a/arch/s390/boot/version.c b/arch/s390/boot/version.c index d32e58bdda6a..fd32f038777f 100644 --- a/arch/s390/boot/version.c +++ b/arch/s390/boot/version.c @@ -1,4 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 +#include #include #include #include "boot.h" diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 4a3f223973f4..e476bcbd9b42 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -29,6 +29,7 @@ #include #include #include +#include #include #define _SETUP diff --git a/arch/x86/boot/version.c b/arch/x86/boot/version.c index a1aaaf6c06a6..945383f0f606 100644 --- a/arch/x86/boot/version.c +++ b/arch/x86/boot/version.c @@ -11,6 +11,7 @@ */ #include "boot.h" +#include #include #include diff --git a/init/.gitignore b/init/.gitignore new file mode 100644 index 000000000000..cbbe270cec00 --- /dev/null +++ b/init/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +/utsversion-tmp.h diff --git a/init/Makefile b/init/Makefile index d82623d7fc8e..ba90eb817185 100644 --- a/init/Makefile +++ b/init/Makefile @@ -19,20 +19,49 @@ mounts-y := do_mounts.o mounts-$(CONFIG_BLK_DEV_RAM) += do_mounts_rd.o mounts-$(CONFIG_BLK_DEV_INITRD) += do_mounts_initrd.o -# dependencies on generated files need to be listed explicitly -$(obj)/version.o: include/generated/compile.h +# +# UTS_VERSION +# -# compile.h changes depending on hostname, generation number, etc, -# so we regenerate it always. -# mkcompile_h will make sure to only update the -# actual file if its content has changed. +smp-flag-$(CONFIG_SMP) := SMP +preempt-flag-$(CONFIG_PREEMPT_BUILD) := PREEMPT +preempt-flag-$(CONFIG_PREEMPT_DYNAMIC) := PREEMPT_DYNAMIC +preempt-flag-$(CONFIG_PREEMPT_RT) := PREEMPT_RT -quiet_cmd_compile.h = CHK $@ - cmd_compile.h = \ - $(CONFIG_SHELL) $(srctree)/scripts/mkcompile_h $@ \ - "$(UTS_MACHINE)" "$(CONFIG_SMP)" "$(CONFIG_PREEMPT_BUILD)" \ - "$(CONFIG_PREEMPT_DYNAMIC)" "$(CONFIG_PREEMPT_RT)" \ - "$(CONFIG_CC_VERSION_TEXT)" "$(LD)" +build-version = $(or $(KBUILD_BUILD_VERSION), $(build-version-auto)) +build-timestamp = $(or $(KBUILD_BUILD_TIMESTAMP), $(build-timestamp-auto)) + +# Maximum length of UTS_VERSION is 64 chars +filechk_uts_version = \ + utsver=$$(echo '$(pound)'"$(build-version)" $(smp-flag-y) $(preempt-flag-y) "$(build-timestamp)" | cut -b -64); \ + echo '$(pound)'define UTS_VERSION \""$${utsver}"\" + +# +# Build version.c with temporary UTS_VERSION +# + +$(obj)/utsversion-tmp.h: FORCE + $(call filechk,uts_version) + +clean-files += utsversion-tmp.h + +$(obj)/version.o: include/generated/compile.h $(obj)/utsversion-tmp.h +CFLAGS_version.o := -include $(obj)/utsversion-tmp.h + +filechk_compile.h = $(srctree)/scripts/mkcompile_h \ + "$(UTS_MACHINE)" "$(CONFIG_CC_VERSION_TEXT)" "$(LD)" include/generated/compile.h: FORCE - $(call cmd,compile.h) + $(call filechk,compile.h) + +# +# Build version-timestamp.c with final UTS_VERSION +# + +include/generated/utsversion.h: build-version-auto = $(shell $(srctree)/$(src)/build-version) +include/generated/utsversion.h: build-timestamp-auto = $(shell LC_ALL=C date) +include/generated/utsversion.h: FORCE + $(call filechk,uts_version) + +$(obj)/version-timestamp.o: include/generated/utsversion.h +CFLAGS_version-timestamp.o := -include include/generated/utsversion.h diff --git a/init/build-version b/init/build-version new file mode 100755 index 000000000000..537d45815083 --- /dev/null +++ b/init/build-version @@ -0,0 +1,10 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0-only + +prev_ver=$(cat .version 2>/dev/null) && +ver=$(expr ${prev_ver} + 1 2>/dev/null) || +ver=1 + +echo ${ver} > .version + +echo ${ver} diff --git a/init/version-timestamp.c b/init/version-timestamp.c new file mode 100644 index 000000000000..179e93bae539 --- /dev/null +++ b/init/version-timestamp.c @@ -0,0 +1,31 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include +#include +#include +#include +#include +#include +#include + +struct uts_namespace init_uts_ns = { + .ns.count = REFCOUNT_INIT(2), + .name = { + .sysname = UTS_SYSNAME, + .nodename = UTS_NODENAME, + .release = UTS_RELEASE, + .version = UTS_VERSION, + .machine = UTS_MACHINE, + .domainname = UTS_DOMAINNAME, + }, + .user_ns = &init_user_ns, + .ns.inum = PROC_UTS_INIT_INO, +#ifdef CONFIG_UTS_NS + .ns.ops = &utsns_operations, +#endif +}; + +/* FIXED STRINGS! Don't touch! */ +const char linux_banner[] = + "Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@" + LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n"; diff --git a/init/version.c b/init/version.c index 3391c4051bf3..01d4ab05f0ba 100644 --- a/init/version.c +++ b/init/version.c @@ -18,24 +18,6 @@ #include #include -struct uts_namespace init_uts_ns = { - .ns.count = REFCOUNT_INIT(2), - .name = { - .sysname = UTS_SYSNAME, - .nodename = UTS_NODENAME, - .release = UTS_RELEASE, - .version = UTS_VERSION, - .machine = UTS_MACHINE, - .domainname = UTS_DOMAINNAME, - }, - .user_ns = &init_user_ns, - .ns.inum = PROC_UTS_INIT_INO, -#ifdef CONFIG_UTS_NS - .ns.ops = &utsns_operations, -#endif -}; -EXPORT_SYMBOL_GPL(init_uts_ns); - static int __init early_hostname(char *arg) { size_t bufsize = sizeof(init_uts_ns.name.nodename); @@ -51,11 +33,6 @@ static int __init early_hostname(char *arg) } early_param("hostname", early_hostname); -/* FIXED STRINGS! Don't touch! */ -const char linux_banner[] = - "Linux version " UTS_RELEASE " (" LINUX_COMPILE_BY "@" - LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION "\n"; - const char linux_proc_banner[] = "%s version %s" " (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ")" @@ -63,3 +40,16 @@ const char linux_proc_banner[] = BUILD_SALT; BUILD_LTO_INFO; + +/* + * init_uts_ns and linux_banner contain the build version and timestamp, + * which are really fixed at the very last step of build process. + * They are compiled with __weak first, and without __weak later. + */ + +struct uts_namespace init_uts_ns __weak; +const char linux_banner[] __weak; + +#include "version-timestamp.c" + +EXPORT_SYMBOL_GPL(init_uts_ns); diff --git a/kernel/gen_kheaders.sh b/kernel/gen_kheaders.sh index 0c78e64f747d..473036b43c83 100755 --- a/kernel/gen_kheaders.sh +++ b/kernel/gen_kheaders.sh @@ -31,8 +31,8 @@ if [ "$building_out_of_srctree" ]; then fi all_dirs="$all_dirs $dir_list" -# include/generated/compile.h is ignored because it is touched even when none -# of the source files changed. +# include/generated/utsversion.h is ignored because it is generated after this +# script is executed. (utsversion.h is unneeded for kheaders) # # When Kconfig regenerates include/generated/autoconf.h, its timestamp is # updated, but the contents might be still the same. When any CONFIG option is @@ -42,7 +42,7 @@ all_dirs="$all_dirs $dir_list" # # Ignore them for md5 calculation to avoid pointless regeneration. headers_md5="$(find $all_dirs -name "*.h" | - grep -v "include/generated/compile.h" | + grep -v "include/generated/utsversion.h" | grep -v "include/generated/autoconf.h" | xargs ls -l | md5sum | cut -d ' ' -f1)" diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh index eecc1863e556..8d982574145a 100755 --- a/scripts/link-vmlinux.sh +++ b/scripts/link-vmlinux.sh @@ -75,6 +75,8 @@ vmlinux_link() objs="${objs} .vmlinux.export.o" fi + objs="${objs} init/version-timestamp.o" + if [ "${SRCARCH}" = "um" ]; then wl=-Wl, ld="${CC}" @@ -213,19 +215,6 @@ if [ "$1" = "clean" ]; then exit 0 fi -# Update version -info GEN .version -if [ -r .version ]; then - VERSION=$(expr 0$(cat .version) + 1) - echo $VERSION > .version -else - rm -f .version - echo 1 > .version -fi; - -# final build of init/ -${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init need-builtin=1 - #link vmlinux.o ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux_o" @@ -260,6 +249,8 @@ if is_enabled CONFIG_MODULES; then ${MAKE} -f "${srctree}/scripts/Makefile.vmlinux" .vmlinux.export.o fi +${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init init/version-timestamp.o + btf_vmlinux_bin_o="" if is_enabled CONFIG_DEBUG_INFO_BTF; then btf_vmlinux_bin_o=.btf.vmlinux.bin.o diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h index ca40a5258c87..f1a820d49e53 100755 --- a/scripts/mkcompile_h +++ b/scripts/mkcompile_h @@ -1,14 +1,9 @@ #!/bin/sh # SPDX-License-Identifier: GPL-2.0 -TARGET=$1 -ARCH=$2 -SMP=$3 -PREEMPT=$4 -PREEMPT_DYNAMIC=$5 -PREEMPT_RT=$6 -CC_VERSION="$7" -LD=$8 +UTS_MACHINE=$1 +CC_VERSION="$2" +LD=$3 # Do not expand names set -f @@ -17,17 +12,6 @@ set -f LC_ALL=C export LC_ALL -if [ -z "$KBUILD_BUILD_VERSION" ]; then - VERSION=$(cat .version 2>/dev/null || echo 1) -else - VERSION=$KBUILD_BUILD_VERSION -fi - -if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then - TIMESTAMP=`date` -else - TIMESTAMP=$KBUILD_BUILD_TIMESTAMP -fi if test -z "$KBUILD_BUILD_USER"; then LINUX_COMPILE_BY=$(whoami | sed 's/\\/\\\\/') else @@ -39,63 +23,12 @@ else LINUX_COMPILE_HOST=$KBUILD_BUILD_HOST fi -UTS_VERSION="#$VERSION" -CONFIG_FLAGS="" -if [ -n "$SMP" ] ; then CONFIG_FLAGS="SMP"; fi +LD_VERSION=$($LD -v | head -n1 | sed 's/(compatible with [^)]*)//' \ + | sed 's/[[:space:]]*$//') -if [ -n "$PREEMPT_RT" ] ; then - CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT_RT" -elif [ -n "$PREEMPT_DYNAMIC" ] ; then - CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT_DYNAMIC" -elif [ -n "$PREEMPT" ] ; then - CONFIG_FLAGS="$CONFIG_FLAGS PREEMPT" -fi - -# Truncate to maximum length -UTS_LEN=64 -UTS_VERSION="$(echo $UTS_VERSION $CONFIG_FLAGS $TIMESTAMP | cut -b -$UTS_LEN)" - -# Generate a temporary compile.h - -{ echo /\* This file is auto generated, version $VERSION \*/ - if [ -n "$CONFIG_FLAGS" ] ; then echo "/* $CONFIG_FLAGS */"; fi - - echo \#define UTS_MACHINE \"$ARCH\" - - echo \#define UTS_VERSION \"$UTS_VERSION\" - - printf '#define LINUX_COMPILE_BY "%s"\n' "$LINUX_COMPILE_BY" - echo \#define LINUX_COMPILE_HOST \"$LINUX_COMPILE_HOST\" - - LD_VERSION=$($LD -v | head -n1 | sed 's/(compatible with [^)]*)//' \ - | sed 's/[[:space:]]*$//') - printf '#define LINUX_COMPILER "%s"\n' "$CC_VERSION, $LD_VERSION" -} > .tmpcompile - -# Only replace the real compile.h if the new one is different, -# in order to preserve the timestamp and avoid unnecessary -# recompilations. -# We don't consider the file changed if only the date/time changed, -# unless KBUILD_BUILD_TIMESTAMP was explicitly set (e.g. for -# reproducible builds with that value referring to a commit timestamp). -# A kernel config change will increase the generation number, thus -# causing compile.h to be updated (including date/time) due to the -# changed comment in the -# first line. - -if [ -z "$KBUILD_BUILD_TIMESTAMP" ]; then - IGNORE_PATTERN="UTS_VERSION" -else - IGNORE_PATTERN="NOT_A_PATTERN_TO_BE_MATCHED" -fi - -if [ -r $TARGET ] && \ - grep -v $IGNORE_PATTERN $TARGET > .tmpver.1 && \ - grep -v $IGNORE_PATTERN .tmpcompile > .tmpver.2 && \ - cmp -s .tmpver.1 .tmpver.2; then - rm -f .tmpcompile -else - echo " UPD $TARGET" - mv -f .tmpcompile $TARGET -fi -rm -f .tmpver.1 .tmpver.2 +cat <