Commit graph

24 commits

Author SHA1 Message Date
Yonghong Song
1fdd7433a9 kbuild: add an elfnote for whether vmlinux is built with lto
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>
2021-04-25 05:25:42 +09:00
Masahiro Yamada
073a9ecb3a init/version.c: remove Version_<LINUX_VERSION_CODE> symbol
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 197dcffc8b ("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 4eb9241127 ("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>
2021-02-26 09:41:04 -08:00
Kirill Tkhai
9a56493f69
uts: Use generic ns_common::count
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>
2020-08-19 14:13:20 +02:00
Thomas Gleixner
457c899653 treewide: Add SPDX license identifier for missed files
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>
2019-05-21 10:50:45 +02:00
Laura Abbott
9afb719e70 kbuild: Add build salt to the kernel and modules
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>
2018-07-18 01:18:05 +09:00
Masahiro Yamada
e4f02fdabd init/version.c: include <linux/export.h> instead of <linux/module.h>
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>
2017-11-17 16:10:02 -08:00
Peter Zijlstra
1e24edca05 locking/atomic, kref: Add KREF_INIT()
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>
2017-01-14 11:37:18 +01:00
Al Viro
33c429405a copy address of proc_ns_ops into ns_common
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-04 14:34:47 -05:00
Al Viro
435d5f4bb2 common object embedded into various struct ....ns
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>
2014-12-04 14:31:00 -05:00
David Howells
0bb80f2405 proc: Split the namespace stuff out into linux/proc_ns.h
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>
2013-05-01 17:29:39 -04:00
Eric W. Biederman
98f842e675 proc: Usable inode numbers for the namespace file descriptors.
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>
2012-11-20 04:19:49 -08:00
Serge E. Hallyn
59607db367 userns: add a user_namespace as creator/owner of uts_namespace
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>
2011-03-23 19:46:59 -07:00
Sam Ravnborg
273b281fa2 kbuild: move utsrelease.h to include/generated
Fix up all users of utsrelease.h

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>
2009-12-12 13:08:15 +01:00
Sam Ravnborg
9204595405 kbuild: move compile.h to include/generated
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>
2009-12-12 13:08:14 +01:00
Daniel Guilak
197dcffc8b init/version.c: define version_string only if CONFIG_KALLSYMS is not defined
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>
2008-07-25 10:53:29 -07:00
Daniel Guilak
277e2c6959 init/version.c: silence sparse warning by declaring the version string
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>
2008-07-25 10:53:28 -07:00
Tim Schmielau
cd354f1ae7 [PATCH] remove many unneeded #includes of sched.h
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>
2007-02-14 08:09:54 -08:00
Linus Torvalds
c71551ad30 Don't put "linux_banner" in the .init section
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>
2007-01-11 18:18:04 -08:00
Roman Zippel
3eb3c740f5 [PATCH] fix linux banner format string
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>
2007-01-10 09:33:59 -08:00
Linus Torvalds
8993780a6e Make SLES9 "get_kernel_version" work on the kernel binary again
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 a2ee8649ba:
"[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>
2006-12-11 11:34:11 -08:00
Herbert Poetzl
a2ee8649ba [PATCH] Fix linux banner utsname information
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>
2006-12-08 08:28:37 -08:00
Serge E. Hallyn
4865ecf131 [PATCH] namespaces: utsname: implement utsname namespaces
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>
2006-10-02 07:57:21 -07:00
Sam Ravnborg
63104eec23 kbuild: introduce utsrelease.h
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>
2006-07-03 23:30:54 +02:00
Linus Torvalds
1da177e4c3 Linux-2.6.12-rc2
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!
2005-04-16 15:20:36 -07:00