BMC/Intel-BMC/linux.git/arch/x86/kernel/msr.c, branch dev

x86, msr: Use seek definitions instead of hard-coded values

2014-10-17T20:40:55+00:00

Replace 0/1 by SEEK_SET/SEEK_CUR. Signed-off-by: Fabian Frederick Link: http://lkml.kernel.org/r/1413576120-27147-1-git-send-email-fabf@skynet.be Signed-off-by: H. Peter Anvin

x86, msr: Convert printk to pr_foo()

2014-10-17T20:40:54+00:00

Also define pr_fmt. Signed-off-by: Fabian Frederick Link: http://lkml.kernel.org/r/1413576110-27103-1-git-send-email-fabf@skynet.be Signed-off-by: H. Peter Anvin

x86, msr: Use PTR_ERR_OR_ZERO

2014-10-17T20:40:53+00:00

Replace IS_ERR/PTR_ERR Signed-off-by: Fabian Frederick Link: http://lkml.kernel.org/r/1413576099-27059-1-git-send-email-fabf@skynet.be Signed-off-by: H. Peter Anvin

x86, msr: Fix CPU hotplug callback registration

2014-03-20T12:43:42+00:00

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" Cc: Thomas Gleixner Cc: Ingo Molnar Signed-off-by: Srivatsa S. Bhat Signed-off-by: Rafael J. Wysocki

x86, msr: Use file_inode(), not f_mapping->host

2013-10-08T19:01:29+00:00

As discussed in [1], exchange f_mapping->host with file_inode(). This is a bug, but happens to be non-manifest in this case. [1] http://lkml.kernel.org/r/20131007190357.GA13318@ZenIV.linux.org.uk Signed-off-by: Andre Richter Link: http://lkml.kernel.org/r/1381224142-3267-1-git-send-email-andre.o.richter@gmail.com Signed-off-by: H. Peter Anvin

x86: delete __cpuinit usage from all x86 files

2013-07-14T23:36:56+00:00

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 Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: x86@kernel.org Acked-by: Ingo Molnar Acked-by: Thomas Gleixner Acked-by: H. Peter Anvin Signed-off-by: Paul Gortmaker

more file_inode() open-coded instances

2013-02-27T21:59:05+00:00

Signed-off-by: Al Viro

x86/msr: Add capabilities check

2013-01-24T16:37:51+00:00

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 Cc: Linus Torvalds Cc: Andrew Morton Cc: Peter Zijlstra Cc: Horses Signed-off-by: Ingo Molnar

Use get_online_cpus to avoid races involving CPU hotplug

2012-09-23T14:43:56+00:00

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 Signed-off-by: Paul E. McKenney

Disintegrate asm/system.h for X86

2012-03-28T17:11:12+00:00

Disintegrate asm/system.h for X86. Signed-off-by: David Howells Acked-by: H. Peter Anvin cc: x86@kernel.org