user/sven/linux.git/scripts/mkcompile_h, branch v5.13.18

kbuild: mkcompile_h: consider timestamp if KBUILD_BUILD_TIMESTAMP is set

2021-07-25T12:37:30Z

[ Upstream commit a979522a1a88556e42a22ce61bccc58e304cb361 ] To avoid unnecessary recompilations, mkcompile_h does not regenerate compile.h if just the timestamp changed. Though, if KBUILD_BUILD_TIMESTAMP is set, an explicit timestamp for the build was requested, in which case we should not ignore it. If a user follows the documentation for reproducible builds [1] and defines KBUILD_BUILD_TIMESTAMP as the git commit timestamp, a clean build will have the correct timestamp. A subsequent cherry-pick (or amend) changes the commit timestamp and if an incremental build is done with a different KBUILD_BUILD_TIMESTAMP now, that new value is not taken into consideration. But it should for reproducibility. Hence, whenever KBUILD_BUILD_TIMESTAMP is explicitly set, do not ignore UTS_VERSION when making a decision about whether the regenerated version of compile.h should be moved into place. [1] https://www.kernel.org/doc/html/latest/kbuild/reproducible-builds.html Signed-off-by: Matthias Maennich Signed-off-by: Masahiro Yamada Signed-off-by: Sasha Levin

kbuild: Use uname for LINUX_COMPILE_HOST detection

2020-10-20T15:46:04Z

`hostname` may not be present on some systems as it's not mandated by POSIX/SUSv4. This isn't just a theoretical problem: on Arch Linux, `hostname` is provided by `inetutils`, which isn't part of the base distribution. ./scripts/mkcompile_h: line 38: hostname: command not found Use `uname -n` instead, which is more likely to be available (and mandated by standards). Signed-off-by: Chris Down Signed-off-by: Masahiro Yamada

kbuild: use CONFIG_CC_VERSION_TEXT to construct LINUX_COMPILER macro

2020-05-12T04:28:33Z

scripts/mkcompile_h runs $(CC) just for getting the version string. Reuse CONFIG_CC_VERSION_TEXT for optimization. For GCC, this slightly changes the version string. I do not think it is a big deal as we do not have the defined format for LINUX_COMPILER. In fact, the recent commit 4dcc9a88448a ("kbuild: mkcompile_h: Include $LD version in /proc/version") added the linker version. Signed-off-by: Masahiro Yamada

kbuild: mkcompile_h: Include $LD version in /proc/version

2020-04-08T15:13:45Z

When doing Clang builds of the kernel, it is possible to link with either ld.bfd (binutils) or ld.lld (LLVM), but it is not possible to discover this from a running kernel. Add the "$LD -v" output to /proc/version. Signed-off-by: Kees Cook Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor Reviewed-by: Fangrui Song Reviewed-by: Sedat Dilek Tested-by: Sedat Dilek Signed-off-by: Masahiro Yamada

kbuild: remove the owner check in mkcompile_h

2020-03-02T12:18:19Z

This reverts a very old commit, which dates back to the pre-git era: |commit 5d1cfb5b12f72145d30ba0f53c9f238144b122b8 |Author: Kai Germaschewski |Date: Sat Jul 27 02:53:19 2002 -0500 | | kbuild: Fix compiling/installing as different users | | "make bzImage && sudo make install" had the problem that during | the "sudo make install" the build system would notice that the information | in include/linux/compile.h is not accurate (it says "compiled by ", | but we are root), thus causing compile.h to be updated and leading to | some recompiles. | | We now only update "compile.h" if the current user is the owner of | include/linux/autoconf.h, i.e. the user who did the "make *config". So the | above sequence will correctly state "compiled by ". | |diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h |index 6313db96172..cd956380978 100755 |--- a/scripts/mkcompile_h |+++ b/scripts/mkcompile_h |@@ -3,6 +3,17 @@ ARCH=$2 | SMP=$3 | CC=$4 | |+# If compile.h exists already and we don't own autoconf.h |+# (i.e. we're not the same user who did make *config), don't |+# modify compile.h |+# So "sudo make install" won't change the "compiled by " |+# do "compiled by root" |+ |+if [ -r $TARGET -a ! -O ../include/linux/autoconf.h ]; then |+ echo ' (not modified)' |+ exit 0 |+fi |+ | if [ -r ../.version ]; then | VERSION=`cat ../.version` | else The 'make bzImage && sudo make install' problem no longer happens because commit 1648e4f80506 ("x86, kbuild: make "make install" not depend on vmlinux") fixed the root cause. Commit 19514fc665ff ("arm, kbuild: make "make install" not depend on vmlinux") fixed the similar issue on ARM, with detailed explanation. So, the rule is that the installation targets should never trigger the builds of any build artifact. By following it, this check is unneeded. Signed-off-by: Masahiro Yamada

mkcompile_h: use printf for LINUX_COMPILE_BY

2019-12-14T06:53:04Z

Commit 858805b336be ("kbuild: add $(BASH) to run scripts with bash-extension") shed light on portability issues. Here is another one. Since commit f07726048d59 ("Fix handling of backlash character in LINUX_COMPILE_BY name"), we must escape a backslash contained in LINUX_COMPILE_BY. This is not working on such distros as Ubuntu. As the POSIX spec [1] says, if any of the operands contain a backslash ( '\' ) character, the results are implementation-defined. The actual shell of /bin/sh could be bash, dash, etc. depending on distros, and the behavior of builtin echo command is different among them. The bash builtin echo, unless -e is given, copies the arguments to stdout without expanding escape sequences (BSD-like behavior). The dash builtin echo, in contrast, adopts System V behavior, which does expand escape sequences without any option given. Even non-builtin /bin/echo behaves differently depending on the system. Due to these variations, echo is considered as a non-portable command. Using printf is the common solution to avoid the portability issue. [1] https://pubs.opengroup.org/onlinepubs/009695399/utilities/echo.html Fixes: 858805b336be ("kbuild: add $(BASH) to run scripts with bash-extension") Reported-by: XXing Wei Signed-off-by: Masahiro Yamada

mkcompile_h: git rid of UTS_TRUNCATE from LINUX_COMPILE_{BY,HOST}

2019-12-14T06:53:04Z

UTS_VERSION is set to struct uts_namespace, hence a too long string should be truncated so it fits in 64 characters. On the other hand, LINUX_COMPILE_BY/HOST are not set to uts_namespace. They are just used in the banners, which do not have specific length limitation. I dug into the git history, but I could not find the reason why these two strings must fit in 64 characters. Remove them. Now that UTS_VERSION is the only user of UTS_TRUNCATE, I squashed it. Signed-off-by: Masahiro Yamada

Kbuild: Handle PREEMPT_RT for version string and magic

2019-08-13T16:10:42Z

Update the build scripts and the version magic to reflect when CONFIG_PREEMPT_RT is enabled in the same way as CONFIG_PREEMPT is treated. The resulting version strings: Linux m 5.3.0-rc1+ #100 SMP Fri Jul 26 ... Linux m 5.3.0-rc1+ #101 SMP PREEMPT Fri Jul 26 ... Linux m 5.3.0-rc1+ #102 SMP PREEMPT_RT Fri Jul 26 ... The module vermagic: 5.3.0-rc1+ SMP mod_unload modversions 5.3.0-rc1+ SMP preempt mod_unload modversions 5.3.0-rc1+ SMP preempt_rt mod_unload modversions Signed-off-by: Thomas Gleixner Signed-off-by: Masahiro Yamada

kbuild: remove unnecessary in-subshell execution

2019-01-28T00:11:17Z

The commands surrounded by ( ) are executed in a subshell, but in most cases, we do not need to spawn an extra subshell. Signed-off-by: Masahiro Yamada

Merge tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2017-11-18T01:45:29Z

Pull Kbuild updates from Masahiro Yamada: "One of the most remarkable improvements in this cycle is, Kbuild is now able to cache the result of shell commands. Some variables are expensive to compute, for example, $(call cc-option,...) invokes the compiler. It is not efficient to redo this computation every time, even when we are not actually building anything. Kbuild creates a hidden file ".cache.mk" that contains invoked shell commands and their results. The speed-up should be noticeable. Summary: - Fix arch build issues (hexagon, sh) - Clean up various Makefiles and scripts - Fix wrong usage of {CFLAGS,LDFLAGS}_MODULE in arch Makefiles - Cache variables that are expensive to compute - Improve cc-ldopton and ld-option for Clang - Optimize output directory creation" * tag 'kbuild-v4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (30 commits) kbuild: move coccicheck help from scripts/Makefile.help to top Makefile sh: decompressor: add shipped files to .gitignore frv: .gitignore: ignore vmlinux.lds selinux: remove unnecessary assignment to subdir- kbuild: specify FORCE in Makefile.headersinst as .PHONY target kbuild: remove redundant mkdir from ./Kbuild kbuild: optimize object directory creation for incremental build kbuild: create object directories simpler and faster kbuild: filter-out PHONY targets from "targets" kbuild: remove redundant $(wildcard ...) for cmd_files calculation kbuild: create directory for make cache only when necessary sh: select KBUILD_DEFCONFIG depending on ARCH kbuild: fix linker feature test macros when cross compiling with Clang kbuild: shrink .cache.mk when it exceeds 1000 lines kbuild: do not call cc-option before KBUILD_CFLAGS initialization kbuild: Cache a few more calls to the compiler kbuild: Add a cache for generated variables kbuild: add forward declaration of default target to Makefile.asm-generic kbuild: remove KBUILD_SUBDIR_ASFLAGS and KBUILD_SUBDIR_CCFLAGS hexagon/kbuild: replace CFLAGS_MODULE with KBUILD_CFLAGS_MODULE ...