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2022-09-29kbuild: build init/built-in.a just onceMasahiro Yamada1-23/+13
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 <masahiroy@kernel.org>
2022-09-29init/version.c: remove #include <linux/version.h>Masahiro Yamada1-1/+0
This is unneeded since commit 073a9ecb3a73 ("init/version.c: remove Version_<LINUX_VERSION_CODE> symbol"). Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2022-07-17init: add "hostname" kernel parameterDan Moulding1-0/+17
The gethostname system call returns the hostname for the current machine. However, the kernel has no mechanism to initially set the current machine's name in such a way as to guarantee that the first userspace process to call gethostname will receive a meaningful result. It relies on some unspecified userspace process to first call sethostname before gethostname can produce a meaningful name. Traditionally the machine's hostname is set from userspace by the init system. The init system, in turn, often relies on a configuration file (say, /etc/hostname) to provide the value that it will supply in the call to sethostname. Consequently, the file system containing /etc/hostname usually must be available before the hostname will be set. There may, however, be earlier userspace processes that could call gethostname before the file system containing /etc/hostname is mounted. Such a process will get some other, likely meaningless, name from gethostname (such as "(none)", "localhost", or "darkstar"). A real-world example where this can happen, and lead to undesirable results, is with mdadm. When assembling arrays, mdadm distinguishes between "local" arrays and "foreign" arrays. A local array is one that properly belongs to the current machine, and a foreign array is one that is (possibly temporarily) attached to the current machine, but properly belongs to some other machine. To determine if an array is local or foreign, mdadm may compare the "homehost" recorded on the array with the current hostname. If mdadm is run before the root file system is mounted, perhaps because the root file system itself resides on an md-raid array, then /etc/hostname isn't yet available and the init system will not yet have called sethostname, causing mdadm to incorrectly conclude that all of the local arrays are foreign. Solving this problem *could* be delegated to the init system. It could be left up to the init system (including any init system that starts within an initramfs, if one is in use) to ensure that sethostname is called before any other userspace process could possibly call gethostname. However, it may not always be obvious which processes could call gethostname (for example, udev itself might not call gethostname, but it could via udev rules invoke processes that do). Additionally, the init system has to ensure that the hostname configuration value is stored in some place where it will be readily accessible during early boot. Unfortunately, every init system will attempt to (or has already attempted to) solve this problem in a different, possibly incorrect, way. This makes getting consistently working configurations harder for users. I believe it is better for the kernel to provide the means by which the hostname may be set early, rather than making this a problem for the init system to solve. The option to set the hostname during early startup, via a kernel parameter, provides a simple, reliable way to solve this problem. It also could make system configuration easier for some embedded systems. [dmoulding@me.com: v2] Link: https://lkml.kernel.org/r/20220506060310.7495-2-dmoulding@me.com Link: https://lkml.kernel.org/r/20220505180651.22849-2-dmoulding@me.com Signed-off-by: Dan Moulding <dmoulding@me.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2021-04-25kbuild: add an elfnote for whether vmlinux is built with ltoYonghong Song1-0/+2
Currently, clang LTO built vmlinux won't work with pahole. LTO introduced cross-cu dwarf tag references and broke current pahole model which handles one cu as a time. The solution is to merge all cu's as one pahole cu as in [1]. We would like to do this merging only if cross-cu dwarf references happens. The LTO build mode is a pretty good indication for that. In earlier version of this patch ([2]), clang flag -grecord-gcc-switches is proposed to add to compilation flags so pahole could detect "-flto" and then merging cu's. This will increate the binary size of 1% without LTO though. Arnaldo suggested to use a note to indicate the vmlinux is built with LTO. Such a cheap way to get whether the vmlinux is built with LTO or not helps pahole but is also useful for tracing as LTO may inline/delete/demote global functions, promote static functions, etc. So this patch added an elfnote with a new type LINUX_ELFNOTE_LTO_INFO. The owner of the note is "Linux". With gcc 8.4.1 and clang trunk, without LTO, I got $ readelf -n vmlinux Displaying notes found in: .notes Owner Data size Description ... Linux 0x00000004 func description data: 00 00 00 00 ... With "readelf -x ".notes" vmlinux", I can verify the above "func" with type code 0x101. With clang thin-LTO, I got the same as above except the following: description data: 01 00 00 00 which indicates the vmlinux is built with LTO. [1] https://lore.kernel.org/bpf/20210325065316.3121287-1-yhs@fb.com/ [2] https://lore.kernel.org/bpf/20210331001623.2778934-1-yhs@fb.com/ Suggested-by: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> Signed-off-by: Yonghong Song <yhs@fb.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v12.0.0-rc4 (x86-64) Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-02-26init/version.c: remove Version_<LINUX_VERSION_CODE> symbolMasahiro Yamada1-8/+0
This code hunk creates a Version_<LINUX_VERSION_CODE> symbol if CONFIG_KALLSYMS is disabled. For example, building the kernel v5.10 for allnoconfig creates the following symbol: $ nm vmlinux | grep Version_ c116b028 B Version_330240 There is no in-tree user of this symbol. Commit 197dcffc8ba0 ("init/version.c: define version_string only if CONFIG_KALLSYMS is not defined") mentions that Version_* is only used with ksymoops. However, a commit in the pre-git era [1] had added the statement, "ksymoops is useless on 2.6. Please use the Oops in its original format". That statement existed until commit 4eb9241127a0 ("Documentation: admin-guide: update bug-hunting.rst") finally removed the stale ksymoops information. This symbol is no longer needed. [1] https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=ad68b2f085f5c79e4759ca2d13947b3c885ee831 Link: https://lkml.kernel.org/r/20210120033452.2895170-1-masahiroy@kernel.org Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Daniel Guilak <guilak@linux.vnet.ibm.com> Cc: Lee Revell <rlrevell@joe-job.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-19uts: Use generic ns_common::countKirill Tkhai1-1/+1
Switch over uts namespaces to use the newly introduced common lifetime counter. Currently every namespace type has its own lifetime counter which is stored in the specific namespace struct. The lifetime counters are used identically for all namespaces types. Namespaces may of course have additional unrelated counters and these are not altered. This introduces a common lifetime counter into struct ns_common. The ns_common struct encompasses information that all namespaces share. That should include the lifetime counter since its common for all of them. It also allows us to unify the type of the counters across all namespaces. Most of them use refcount_t but one uses atomic_t and at least one uses kref. Especially the last one doesn't make much sense since it's just a wrapper around refcount_t since 2016 and actually complicates cleanup operations by having to use container_of() to cast the correct namespace struct out of struct ns_common. Having the lifetime counter for the namespaces in one place reduces maintenance cost. Not just because after switching all namespaces over we will have removed more code than we added but also because the logic is more easily understandable and we indicate to the user that the basic lifetime requirements for all namespaces are currently identical. Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com> Reviewed-by: Kees Cook <keescook@chromium.org> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/159644978167.604812.1773586504374412107.stgit@localhost.localdomain Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2019-05-21treewide: Add SPDX license identifier for missed filesThomas Gleixner1-0/+1
Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-07-18kbuild: Add build salt to the kernel and modulesLaura Abbott1-0/+3
In Fedora, the debug information is packaged separately (foo-debuginfo) and can be installed separately. There's been a long standing issue where only one version of a debuginfo info package can be installed at a time. There's been an effort for Fedora for parallel debuginfo to rectify this problem. Part of the requirement to allow parallel debuginfo to work is that build ids are unique between builds. The existing upstream rpm implementation ensures this by re-calculating the build-id using the version and release as a seed. This doesn't work 100% for the kernel because of the vDSO which is its own binary and doesn't get updated when embedded. Fix this by adding some data in an ELF note for both the kernel and modules. The data is controlled via a Kconfig option so distributions can set it to an appropriate value to ensure uniqueness between builds. Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com> Signed-off-by: Laura Abbott <labbott@redhat.com> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
2017-11-17init/version.c: include <linux/export.h> instead of <linux/module.h>Masahiro Yamada1-1/+1
init/version.c has nothing to do with modules, so remove the <linux/modude.h>. Instead, include <linux/export.h> for EXPORT_SYMBOL_GPL. This cuts off a lot of unnecessary header parsing. Link: http://lkml.kernel.org/r/1505920984-8523-1-git-send-email-yamada.masahiro@socionext.com Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-01-14locking/atomic, kref: Add KREF_INIT()Peter Zijlstra1-3/+1
Since we need to change the implementation, stop exposing internals. Provide KREF_INIT() to allow static initialization of struct kref. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-12-04copy address of proc_ns_ops into ns_commonAl Viro1-0/+3
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-04common object embedded into various struct ....nsAl Viro1-1/+1
for now - just move corresponding ->proc_inum instances over there Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-05-01proc: Split the namespace stuff out into linux/proc_ns.hDavid Howells1-1/+1
Split the proc namespace stuff out into linux/proc_ns.h. Signed-off-by: David Howells <dhowells@redhat.com> cc: netdev@vger.kernel.org cc: Serge E. Hallyn <serge.hallyn@ubuntu.com> cc: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-11-20proc: Usable inode numbers for the namespace file descriptors.Eric W. Biederman1-0/+2
Assign a unique proc inode to each namespace, and use that inode number to ensure we only allocate at most one proc inode for every namespace in proc. A single proc inode per namespace allows userspace to test to see if two processes are in the same namespace. This has been a long requested feature and only blocked because a naive implementation would put the id in a global space and would ultimately require having a namespace for the names of namespaces, making migration and certain virtualization tricks impossible. We still don't have per superblock inode numbers for proc, which appears necessary for application unaware checkpoint/restart and migrations (if the application is using namespace file descriptors) but that is now allowd by the design if it becomes important. I have preallocated the ipc and uts initial proc inode numbers so their structures can be statically initialized. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2011-03-23userns: add a user_namespace as creator/owner of uts_namespaceSerge E. Hallyn1-0/+1
The expected course of development for user namespaces targeted capabilities is laid out at https://wiki.ubuntu.com/UserNamespace. Goals: - Make it safe for an unprivileged user to unshare namespaces. They will be privileged with respect to the new namespace, but this should only include resources which the unprivileged user already owns. - Provide separate limits and accounting for userids in different namespaces. Status: Currently (as of 2.6.38) you can clone with the CLONE_NEWUSER flag to get a new user namespace if you have the CAP_SYS_ADMIN, CAP_SETUID, and CAP_SETGID capabilities. What this gets you is a whole new set of userids, meaning that user 500 will have a different 'struct user' in your namespace than in other namespaces. So any accounting information stored in struct user will be unique to your namespace. However, throughout the kernel there are checks which - simply check for a capability. Since root in a child namespace has all capabilities, this means that a child namespace is not constrained. - simply compare uid1 == uid2. Since these are the integer uids, uid 500 in namespace 1 will be said to be equal to uid 500 in namespace 2. As a result, the lxc implementation at lxc.sf.net does not use user namespaces. This is actually helpful because it leaves us free to develop user namespaces in such a way that, for some time, user namespaces may be unuseful. Bugs aside, this patchset is supposed to not at all affect systems which are not actively using user namespaces, and only restrict what tasks in child user namespace can do. They begin to limit privilege to a user namespace, so that root in a container cannot kill or ptrace tasks in the parent user namespace, and can only get world access rights to files. Since all files currently belong to the initila user namespace, that means that child user namespaces can only get world access rights to *all* files. While this temporarily makes user namespaces bad for system containers, it starts to get useful for some sandboxing. I've run the 'runltplite.sh' with and without this patchset and found no difference. This patch: copy_process() handles CLONE_NEWUSER before the rest of the namespaces. So in the case of clone(CLONE_NEWUSER|CLONE_NEWUTS) the new uts namespace will have the new user namespace as its owner. That is what we want, since we want root in that new userns to be able to have privilege over it. Changelog: Feb 15: don't set uts_ns->user_ns if we didn't create a new uts_ns. Feb 23: Move extern init_user_ns declaration from init/version.c to utsname.h. Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Daniel Lezcano <daniel.lezcano@free.fr> Acked-by: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-12-12kbuild: move utsrelease.h to include/generatedSam Ravnborg1-1/+1
Fix up all users of utsrelease.h Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Michal Marek <mmarek@suse.cz>
2009-12-12kbuild: move compile.h to include/generatedSam Ravnborg1-1/+1
Signed-off-by: Sam Ravnborg <sam@ravnborg.org> Signed-off-by: Michal Marek <mmarek@suse.cz>
2008-07-25init/version.c: define version_string only if CONFIG_KALLSYMS is not definedDaniel Guilak1-0/+2
int Version_* is only used with ksymoops, which is only needed (according to README and Documentation/Changes) if CONFIG_KALLSYMS is NOT defined. Therefore this patch defines version_string only if CONFIG_KALLSYMS is not defined. Signed-off-by: Daniel Guilak <daniel@danielguilak.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25init/version.c: silence sparse warning by declaring the version stringDaniel Guilak1-0/+1
Signed-off-by: Daniel Guilak <daniel@danielguilak.com> Cc: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-02-14[PATCH] remove many unneeded #includes of sched.hTim Schmielau1-1/+0
After Al Viro (finally) succeeded in removing the sched.h #include in module.h recently, it makes sense again to remove other superfluous sched.h includes. There are quite a lot of files which include it but don't actually need anything defined in there. Presumably these includes were once needed for macros that used to live in sched.h, but moved to other header files in the course of cleaning it up. To ease the pain, this time I did not fiddle with any header files and only removed #includes from .c-files, which tend to cause less trouble. Compile tested against 2.6.20-rc2 and 2.6.20-rc2-mm2 (with offsets) on alpha, arm, i386, ia64, mips, powerpc, and x86_64 with allnoconfig, defconfig, allmodconfig, and allyesconfig as well as a few randconfigs on x86_64 and all configs in arch/arm/configs on arm. I also checked that no new warnings were introduced by the patch (actually, some warnings are removed that were emitted by unnecessarily included header files). Signed-off-by: Tim Schmielau <tim@physik3.uni-rostock.de> Acked-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-01-11Don't put "linux_banner" in the .init sectionLinus Torvalds1-2/+2
It might save a few bytes after bootup, but it causes the string to be linked in at the end of the final vmlinux image, which defeats the whole point of doing all this, namely allowing some broken user-space binaries to search for the kernel version string in the kernel binary. So just remove the __init specifier. Cc: Olaf Hering <olaf@aepfle.de> Cc: Jean Delvare <khali@linux-fr.org> Cc: Roman Zippel <zippel@linux-m68k.org> Cc: Andrey Borzenkov <arvidjaar@mail.ru> Cc: Andrew Morton <akpm@osdl.org> Acked-by: Andy Whitcroft <apw@shadowen.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2007-01-10[PATCH] fix linux banner format stringRoman Zippel1-0/+10
Revert previous attempts at messing with the linux banner string and simply use a separate format string for proc. Signed-off-by: Roman Zippel <zippel@linux-m68k.org> Acked-by: Olaf Hering <olaf@aepfle.de> Acked-by: Jean Delvare <khali@linux-fr.org> Cc: Andrey Borzenkov <arvidjaar@mail.ru> Cc: Andrew Morton <akpm@osdl.org> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Herbert Poetzl <herbert@13thfloor.at> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-11Make SLES9 "get_kernel_version" work on the kernel binary againLinus Torvalds1-5/+0
As reported by Andy Whitcroft, at least the SLES9 initrd build process depends on getting the kernel version from the kernel binary. It does that by simply trawling the binary and looking for the signature of the "linux_banner" string (the string "Linux version " to be exact. Which is really broken in itself, but whatever..) That got broken when the string was changed to allow /proc/version to change the UTS release information dynamically, and "get_kernel_version" thus returned "%s" (see commit a2ee8649ba6d71416712e798276bf7c40b64e6e5: "[PATCH] Fix linux banner utsname information"). This just restores "linux_banner" as a static string, which should fix the version finding. And /proc/version simply uses a different string. To avoid wasting even that miniscule amount of memory, the early boot string should really be marked __initdata, but that just causes the same bug in SLES9 to re-appear, since it will then find other occurrences of "Linux version " first. Cc: Andy Whitcroft <apw@shadowen.org> Acked-by: Herbert Poetzl <herbert@13thfloor.at> Cc: Andi Kleen <ak@suse.de> Cc: Andrew Morton <akpm@osdl.org> Cc: Steve Fox <drfickle@us.ibm.com> Acked-by: Olaf Hering <olaf@aepfle.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-08[PATCH] Fix linux banner utsname informationHerbert Poetzl1-2/+3
utsname information is shown in the linux banner, which also is used for /proc/version (which can have different utsname values inside a uts namespaces). this patch makes the varying data arguments and changes the string to a format string, using those arguments. Signed-off-by: Herbert Poetzl <herbert@13thfloor.at> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-02[PATCH] namespaces: utsname: implement utsname namespacesSerge E. Hallyn1-9/+14
This patch defines the uts namespace and some manipulators. Adds the uts namespace to task_struct, and initializes a system-wide init namespace. It leaves a #define for system_utsname so sysctl will compile. This define will be removed in a separate patch. [akpm@osdl.org: build fix, cleanup] Signed-off-by: Serge Hallyn <serue@us.ibm.com> Cc: Kirill Korotaev <dev@openvz.org> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Herbert Poetzl <herbert@13thfloor.at> Cc: Andrey Savochkin <saw@sw.ru> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-03kbuild: introduce utsrelease.hSam Ravnborg1-0/+1
include/linux/version.h contained both actual KERNEL version and UTS_RELEASE that contains a subset from git SHA1 for when kernel was compiled as part of a git repository. This had the unfortunate side-effect that all files including version.h would be recompiled when some git changes was made due to changes SHA1. Split it out so we keep independent parts in separate files. Also update checkversion.pl script to no longer check for UTS_RELEASE. Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
2005-04-16Linux-2.6.12-rc2v2.6.12-rc2Linus Torvalds1-0/+33
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!