Cpio format reserves 8 bytes for an ASCII representation of a time_t timestamp.
While 2106-02-07 06:28:15 UTC (time_t = 0xffffffff) is still some years in the
future, a poorly chosen date string for KBUILD_BUILD_TIMESTAMP, converted into
seconds since the epoch, might lead to exceeded cpio timestamp limits that
result in a broken cpio archive. Add timestamp checks to prevent overrun of
the 8-byte cpio header field.
My colleague Thomas Kühnel discovered the behaviour, when we accidentally fed
SOURCE_DATE_EPOCH to KBUILD_BUILD_TIMESTAMP as is: some timestamps (e.g.
1607420928 = 2021-12-08 9:48:48 UTC) will be interpreted by `date` as a valid
date specification of science fictional times (here: year 160742). Even though
this is bad input for KBUILD_BUILD_TIMESTAMP, it should not break the initramfs
cpio format.
Signed-off-by: Nicolas Schier <nicolas@fjasle.eu>
Cc: Thomas Kühnel <thomas.kuehnel@avm.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Add 'const' to constant arrays. I also added missing 'static'.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
LANG gives a weak default to each LC_* in case it is not explicitly
defined. LC_ALL, if set, overrides all other LC_* variables.
LANG < LC_CTYPE, LC_COLLATE, LC_MONETARY, LC_NUMERIC, ... < LC_ALL
This is why documentation such as [1] suggests to set LC_ALL in build
scripts to get the deterministic result.
LANG=C is not strong enough to override LC_* that may be set by end
users.
[1]: https://reproducible-builds.org/docs/locales/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Reviewed-by: Matthias Maennich <maennich@google.com>
Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net> (mptcp)
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The current .gitignore intends to ignore everything under usr/include/
except .gitignore and Makefile.
A cleaner solution is to use a pattern suffixed with '/', which matches
only directories. It works well here because all the exported headers
are located in sub-directories, like <linux/*.h>, <asm/*.h>.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Pull Kbuild updates from Masahiro Yamada:
- Fix false-positive build warnings for ARCH=ia64 builds
- Optimize dictionary size for module compression with xz
- Check the compiler and linker versions in Kconfig
- Fix misuse of extra-y
- Support DWARF v5 debug info
- Clamp SUBLEVEL to 255 because stable releases 4.4.x and 4.9.x
exceeded the limit
- Add generic syscall{tbl,hdr}.sh for cleanups across arches
- Minor cleanups of genksyms
- Minor cleanups of Kconfig
* tag 'kbuild-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (38 commits)
initramfs: Remove redundant dependency of RD_ZSTD on BLK_DEV_INITRD
kbuild: remove deprecated 'always' and 'hostprogs-y/m'
kbuild: parse C= and M= before changing the working directory
kbuild: reuse this-makefile to define abs_srctree
kconfig: unify rule of config, menuconfig, nconfig, gconfig, xconfig
kconfig: omit --oldaskconfig option for 'make config'
kconfig: fix 'invalid option' for help option
kconfig: remove dead code in conf_askvalue()
kconfig: clean up nested if-conditionals in check_conf()
kconfig: Remove duplicate call to sym_get_string_value()
Makefile: Remove # characters from compiler string
Makefile: reuse CC_VERSION_TEXT
kbuild: check the minimum linker version in Kconfig
kbuild: remove ld-version macro
scripts: add generic syscallhdr.sh
scripts: add generic syscalltbl.sh
arch: syscalls: remove $(srctree)/ prefix from syscall tables
arch: syscalls: add missing FORCE and fix 'targets' to make if_changed work
gen_compile_commands: prune some directories
kbuild: simplify access to the kernel's version
...
Commit be1859bdc6 ("initramfs: remove redundant dependency on
BLK_DEV_INITRD") removed all redundant dependencies on BLK_DEV_INITRD,
but the recent addition of zstd support introduced a new one.
Fixes: a30d8a39f0 ("usr: Add support for zstd compressed initramfs")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Pull fdpick coredump update from Al Viro:
"Switches fdpic coredumps away from original aout dumping primitives to
the same kind of regset use as regular elf coredumps do"
* 'work.fdpic' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
[elf-fdpic] switch coredump to regsets
[elf-fdpic] use elf_dump_thread_status() for the dumper thread as well
[elf-fdpic] move allocation of elf_thread_status into elf_dump_thread_status()
[elf-fdpic] coredump: don't bother with cyclic list for per-thread objects
kill elf_fpxregs_t
take fdpic-related parts of elf_prstatus out
unexport linux/elfcore.h
- Add support for a zstd compressed initramfs.
- Add compression for compressing built-in initramfs with zstd.
I have tested this patch by boot testing with buildroot and QEMU.
Specifically, I booted the kernel with both a zstd and gzip compressed
initramfs, both built into the kernel and separate. I ensured that the
correct compression algorithm was used. I tested on arm, aarch64, i386,
and x86_64.
This patch has been tested in production on aarch64 and x86_64 devices.
Additionally, I have performance measurements from internal use in
production. On an aarch64 device we saw 19 second boot time improvement
from switching from lzma to zstd (27 seconds to 8 seconds). On an x86_64
device we saw a 9 second boot time reduction from switching from xz to
zstd.
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20200730190841.2071656-5-nickrterrell@gmail.com
It's unusable from userland - it uses elf_gregset_t, which is not
provided by exported headers. glibc has it in sys/procfs.h, but
the same file defines struct elf_prstatus, so linux/elfcore.h can't
be included once sys/procfs.h has been pulled. Same goes for uclibc
and dietlibc simply doesn't have elf_gregset_t defined anywhere.
IOW, no userland source is including that thing.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
bpfilter_umh is built for the default machine bit of the compiler,
which may not match to the bit size of the kernel.
This happens in the scenario below:
You can use biarch GCC that defaults to 64-bit for building the 32-bit
kernel. In this case, Kbuild passes -m32 to teach the compiler to
produce 32-bit kernel space objects. However, it is missing when
building bpfilter_umh. It is built as a 64-bit ELF, and then embedded
into the 32-bit kernel.
The 32-bit kernel and 64-bit umh is a bad combination.
In theory, we can have 32-bit umh running on 64-bit kernel, but we do
not have a good reason to support such a usecase.
The best is to match the bit size between them.
Pass -m32 or -m64 to the umh build command if it is found in
$(KBUILD_CFLAGS). Evaluate CC_CAN_LINK against the kernel bit-size.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This omits system headers from the generated header dependency.
System headers are not updated unless you upgrade the compiler. Nor do
they contain CONFIG options, so fixdep does not need to parse them.
Having said that, the effect of this optimization will be quite small
because the kernel code generally does not include system headers
except <stdarg.h>. Host programs include a lot of system headers,
but there are not so many in the kernel tree.
At first, keeping system headers in .*.cmd files might be useful to
detect the compiler update, but there is no guarantee that <stdarg.h>
is included from every file. So, I implemented a more reliable way in
the previous commit.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Even though INITRAMFS_SOURCE kconfig option isn't set in most of
defconfigs it is used (set) extensively by various build systems.
Commit f26661e127 ("initramfs: make initramfs compression choice
non-optional") has changed default compression mode. Previously we
compress initramfs using available compression algorithm. Now
we don't use any compression at all by default.
It significantly increases the image size in case of build system
chooses embedded initramfs. Initially I faced with this issue while
using buildroot.
As of today it's not possible to set preferred compression mode
in target defconfig as this option depends on INITRAMFS_SOURCE
being set. Modification of all build systems either doesn't look
like good option.
Let's instead rewrite initramfs compression mode choices list
the way that "INITRAMFS_COMPRESSION_NONE" will be the last option
in the list. In that case it will be chosen only if all other
options (which implements any compression) are not available.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Pull more Kbuild updates from Masahiro Yamada:
- fix randconfig to generate a sane .config
- rename hostprogs-y / always to hostprogs / always-y, which are more
natual syntax.
- optimize scripts/kallsyms
- fix yes2modconfig and mod2yesconfig
- make multiple directory targets ('make foo/ bar/') work
* tag 'kbuild-v5.6-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
kbuild: make multiple directory targets work
kconfig: Invalidate all symbols after changing to y or m.
kallsyms: fix type of kallsyms_token_table[]
scripts/kallsyms: change table to store (strcut sym_entry *)
scripts/kallsyms: rename local variables in read_symbol()
kbuild: rename hostprogs-y/always to hostprogs/always-y
kbuild: fix the document to use extra-y for vmlinux.lds
kconfig: fix broken dependency in randconfig-generated .config
Since commit ddd09bcc89 ("initramfs: make compression options not
depend on INITRAMFS_SOURCE"), Kconfig asks the compression mode for
the built-in initramfs regardless of INITRAMFS_SOURCE.
It is technically simpler, but pointless from a UI perspective,
Linus says [1].
When INITRAMFS_SOURCE is empty, usr/Makefile creates a tiny default
cpio, which is so small that nobody cares about the compression.
This commit hides the Kconfig choice in that case. The default cpio
is embedded without compression, which was the original behavior.
[1]: https://lkml.org/lkml/2020/2/1/160
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.
It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.
This commit renames like follows:
always -> always-y
hostprogs-y -> hostprogs
So, scripts/Makefile will look like this:
always-$(CONFIG_BUILD_BIN2C) += ...
always-$(CONFIG_KALLSYMS) += ...
...
hostprogs := $(always-y) $(always-m)
I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.
The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This script sets the -e option, so it exits on any error, in which
case it exits without cleaning up the intermediate cpio_list.
Make sure to delete it on exit.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Currently, usr/gen_initramfs.sh takes care of all the use-cases:
[1] generates a cpio file unless CONFIG_INITRAMFS_SOURCE points to
a single cpio archive
[2] If CONFIG_INITRAMFS_SOURCE is the path to a cpio archive,
use it as-is.
[3] Compress the cpio file according to CONFIG_INITRAMFS_COMPRESSION_*
unless it is passed a compressed archive.
To simplify the script, move [2] and [3] to usr/Makefile.
If CONFIG_INITRAMFS_SOURCE is the path to a cpio archive, there is
no need to run this shell script.
For the cpio archive compression, you can re-use the rules from
scripts/Makefile.lib .
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Currently, this script outputs a cpio file when -o option is
given, but otherwise a text file in the format recognized by
gen_init_cpio.
This behavior is unclear. Make it always output a cpio file.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
When CONFIG_INITRAMFS_SOURCE is empty, the Makefile passes the -d
option to gen_initramfs.sh to create the default initramfs, which
contains /dev, /dev/console, and /root.
This commit simplifies the default behavior; remove the -d option,
and add the default cpio list.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Currently, this script is run twice, for the dependency list, and then
for the cpio archive.
The first one is re-run every time although its build log is suppressed
so nobody notices it.
Make it work more efficiently by generating the cpio and the dependency
list at the same time.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
