Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:
get_online_cpus();
for_each_online_cpu(cpu)
init_cpu(cpu);
register_cpu_notifier(&foobar_cpu_notifier);
put_online_cpus();
This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).
Instead, the correct and race-free way of performing the callback
registration is:
cpu_notifier_register_begin();
for_each_online_cpu(cpu)
init_cpu(cpu);
/* Note the use of the double underscored version of the API */
__register_cpu_notifier(&foobar_cpu_notifier);
cpu_notifier_register_done();
Fix the msr code in x86 by using this latter form of callback registration.
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings. In any case, they are temporary and harmless.
This removes all the arch/x86 uses of the __cpuinit macros from
all C files. x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
At the moment the MSR driver only relies upon file system
checks. This means that anything as root with any capability set
can write to MSRs. Historically that wasn't very interesting but
on modern processors the MSRs are such that writing to them
provides several ways to execute arbitary code in kernel space.
Sample code and documentation on doing this is circulating and
MSR attacks are used on Windows 64bit rootkits already.
In the Linux case you still need to be able to open the device
file so the impact is fairly limited and reduces the security of
some capability and security model based systems down towards
that of a generic "root owns the box" setup.
Therefore they should require CAP_SYS_RAWIO to prevent an
elevation of capabilities. The impact of this is fairly minimal
on most setups because they don't have heavy use of
capabilities. Those using SELinux, SMACK or AppArmor rules might
want to consider if their rulesets on the MSR driver could be
tighter.
Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Horses <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If arch/x86/kernel/msr.c is a module, a CPU might offline or online
between the for_each_online_cpu(i) loop and the call to
register_hotcpu_notifier in msr_init or the call to
unregister_hotcpu_notifier in msr_exit. The potential races can lead
to leaks/duplicates, attempts to destroy non-existant devices, or
random pointer dereferences.
For example, in msr_init if:
for_each_online_cpu(i) {
err = msr_device_create(i);
if (err != 0)
goto out_class;
}
<----- CPU offlines
register_hotcpu_notifier(&msr_class_cpu_notifier);
and the CPU never onlines before msr_exit, then the module will never
call msr_device_destroy for the associated CPU.
This fix surrounds for_each_online_cpu and register_hotcpu_notifier or
unregister_hotcpu_notifier with get_online_cpus+put_online_cpus.
Tested on a VM.
Signed-off-by: Silas Boyd-Wickizer <sbw@mit.edu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
both callers of device_get_devnode() are only interested in lower 16bits
and nobody tries to return anything wider than 16bit anyway.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The big kernel lock has been removed from all these files at some point,
leaving only the #include.
Remove this too as a cleanup.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
By the previous modification, the cpu notifier can return encapsulate
errno value. This converts the cpu notifiers for msr, cpuid, and
therm_throt.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Pass the number of minors when unregistering MSR and CPUID drivers.
Reported-by: Dean Nelson <dnelson@redhat.com>
Signed-off-by: Dean Nelson <dnelson@redhat.com>
LKML-Reference: <20100127023722.GA22305@sgi.com>
Signed-off-by: Russ Anderson <rja@sgi.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
register_chrdev() hardcodes registering 256 minors, presumably to
avoid breaking old drivers. However, we need to register enough
minors so that we have all possible CPUs.
checkpatch warns on this patch, but the patch is correct: NR_CPUS here
is a static *upper bound* on the *maximum CPU index* (not *number of
CPUs!*) and that is what we want.
Reported-and-tested-by: Russ Anderson <rja@sgi.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
LKML-Reference: <tip-*@git.kernel.org>
The MSR driver would compute the values for cpu and c at declaration,
and then again in the body of the function. This isn't merely
redundant, but unsafe, since cpu might not refer to a valid CPU at
that point.
Remove the unnecessary and dangerous references in the declarations.
This code now matches the equivalent code in the CPUID driver.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
* 'x86-cpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, msr, cpumask: Use struct cpumask rather than the deprecated cpumask_t
x86, cpuid: Simplify the code in cpuid_open
x86, cpuid: Remove the bkl from cpuid_open()
x86, msr: Remove the bkl from msr_open()
x86: AMD Geode LX optimizations
x86, msr: Unify rdmsr_on_cpus/wrmsr_on_cpus
Remove the big kernel lock from msr_open() as it doesn't protect
anything there.
The only racy event that can happen here is a concurrent cpu shutdown.
So let's look at what could be racy during/after the above event:
- The cpu_online() check is racy, but the bkl doesn't help about
that anyway it disables preemption but we may be chcking another
cpu than the current one.
Also the cpu can still become offlined between open and read calls.
- The cpu_data(cpu) returns a safe pointer too. It won't be released on
cpu offlining. But some fields can be changed from
arch/x86/kernel/smpboot.c:remove_siblinginfo() :
- phys_proc_id
- cpu_core_id
Those are not read from msr_open(). What we are checking is the
x86_capability that is left untouched on offlining.
So this removal looks safe.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: John Kacur <jkacur@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Sven-Thorsten Dietrich <sdietrich@suse.de>
LKML-Reference: <1254944602-7382-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This allows subsytems to provide devtmpfs with non-default permissions
for the device node. Instead of the default mode of 0600, null, zero,
random, urandom, full, tty, ptmx now have a mode of 0666, which allows
non-privileged processes to access standard device nodes in case no
other userspace process applies the expected permissions.
This also fixes a wrong assignment in pktcdvd and a checkpatch.pl complain.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Make it possible to access the all-register-setting/getting MSR
functions via the MSR driver. This is implemented as an ioctl() on
the standard MSR device node.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Borislav Petkov <petkovbb@gmail.com>
For some reason, the _safe MSR functions returned -EFAULT, not -EIO.
However, the only user which cares about the return code as anything
other than a boolean is the MSR driver, which wants -EIO. Change it
to -EIO across the board.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
This adds support to the x86 cpuid and msr drivers to report the proper
device name to userspace for their devices.
Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Jan Blunck <jblunck@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Impact: Reduce future system panics due to cpumask operations using NR_CPUS
Insure that code does not look at bits >= nr_cpu_ids as when cpumasks are
allocated based on nr_cpu_ids, these extra bits will not be defined.
Also some other minor updates:
* change in to use cpu accessor function set_cpu_present() instead of
directly accessing cpu_present_map w/cpu_clear() [arch/x86/kernel/reboot.c]
* use cpumask_of() instead of &cpumask_of_cpu() [arch/x86/kernel/reboot.c]
* optimize some cpu_mask_to_apicid_and functions.
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Return the correct return value when the MSR driver partially
completes a request (we should return the number of bytes actually
read or written, instead of the error code.)
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Propagate error (-ENXIO) from smp_call_function_single(). These
errors can happen when a CPU is unplugged while the MSR driver is
open.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
msr_open tests for someone trying to open a device for a nonexistent CPU.
However, the function always returns 0, not ret like it should, hence
userspace can BUG the kernel trivially. This bug was introduced by the
cdev lock_kernel pushdown patch last May.
The BUG can be reproduced with these commands:
# mknod fubar c 202 8 <-- pick a number less than NR_CPUS that is not
the number of an online CPU
# cat fubar
Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
device_create() is race-prone, so use the race-free
device_create_drvdata() instead as device_create() is going away.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
After 2.6.24 there was a plan to make the PM core acquire all device
semaphores during a suspend/hibernation to protect itself from
concurrent operations involving device objects. That proved to be
too heavy-handed and we found a better way to achieve the goal, but
before it happened, we had introduced the functions
device_pm_schedule_removal() and destroy_suspended_device() to allow
drivers to "safely" destroy a suspended device and we had adapted some
drivers to use them. Now that these functions are no longer necessary,
it seems reasonable to remove them and modify their users to use the
normal device unregistration instead.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Instead of grabbing the BKL on seek, use the inode mutex in the style
of generic_file_llseek().
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Fix the following warnings:
WARNING: arch/x86/kernel/built-in.o(.exit.text+0xf8): Section mismatch in reference from the function msr_exit() to the variable .cpuinit.data:msr_class_cpu_notifier
WARNING: arch/x86/kernel/built-in.o(.exit.text+0x158): Section mismatch in reference from the function cpuid_exit() to the variable .cpuinit.data:cpuid_class_cpu_notifier
WARNING: arch/x86/kernel/built-in.o(.exit.text+0x171): Section mismatch in reference from the function microcode_exit() to the variable .cpuinit.data:mc_cpu_notifier
In all three cases there were a function annotated __exit
that referenced a variable annotated __cpuinitdata.
The fix was to replace the annotation of the notifier
with __refdata to tell modpost that the reference to
a _cpuinit function in the notifier are OK.
The unregister call that references the notifier
variable will simple delete the function pointer
so there is no problem ignoring the reference.
Note: This looks like another case where __cpuinit
has been used as replacement for proper use
of CONFIG_HOTPLUG_CPU to decide what code are used for
HOTPLUG_CPU.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch reorganizes the way suspend and resume notifications are
sent to drivers. The major changes are that now the PM core acquires
every device semaphore before calling the methods, and calls to
device_add() during suspends will fail, while calls to device_del()
during suspends will block.
It also provides a way to safely remove a suspended device with the
help of the PM core, by using the device_pm_schedule_removal() callback
introduced specifically for this purpose, and updates two drivers (msr
and cpuid) that need to use it.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
cpu_data is currently an array defined using NR_CPUS. This means that
we overallocate since we will rarely really use maximum configured cpus.
When NR_CPU count is raised to 4096 the size of cpu_data becomes
3,145,728 bytes.
These changes were adopted from the sparc64 (and ia64) code. An
additional field was added to cpuinfo_x86 to be a non-ambiguous cpu
index. This corresponds to the index into a cpumask_t as well as the
per_cpu index. It's used in various places like show_cpuinfo().
cpu_data is defined to be the boot_cpu_data structure for the NON-SMP
case.
Signed-off-by: Mike Travis <travis@sgi.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Cc: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
msr_class_cpu_callback() can be marked __cpuinit, being the notifier callback
for a __cpuinitdata notifier_block. So can be marked msr_device_create() too,
called only from the newly-__cpuinit msr_class_cpu_callback() or from
__init-marked msr_init().
Signed-off-by: Satyam Sharma <satyam@infradead.org>
Cc: Andi Kleen <ak@suse.de>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
msr_class_cpu_callback() can be marked __cpuinit, being the notifier
callback for a __cpuinitdata notifier_block. So can be marked
msr_device_create() too, called only from the newly-__cpuinit
msr_class_cpu_callback() or from __init-marked msr_init().
[ tglx: arch/x86 adaptation ]
Signed-off-by: Satyam Sharma <satyam@infradead.org>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Since the x86 merge, lots of files that referenced their own filenames
are no longer correct. Rather than keep them up to date, just delete
them, as they add no real value.
Additionally:
- fix up comment formatting in scx200_32.c
- Remove a credit from myself in setup_64.c from a time when we had no SCM
- remove longwinded history from tsc_32.c which can be figured out from
git.
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Srivatsa S. Bhat