linux-stable.git/arch/x86/kernel/cpu/common.c, branch linux-3.4.y

x86/ldt: Make modify_ldt synchronous

2016-03-21T01:17:50+00:00

commit 37868fe113ff2ba814b3b4eb12df214df555f8dc upstream.

modify_ldt() has questionable locking and does not synchronize
threads.  Improve it: redesign the locking and synchronize all
threads' LDTs using an IPI on all modifications.

This will dramatically slow down modify_ldt in multithreaded
programs, but there shouldn't be any multithreaded programs that
care about modify_ldt's performance in the first place.

This fixes some fallout from the CVE-2015-5157 fixes.

Signed-off-by: Andy Lutomirski 
Reviewed-by: Borislav Petkov 
Cc: Andrew Cooper 
Cc: Andy Lutomirski 
Cc: Boris Ostrovsky 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Jan Beulich 
Cc: Konrad Rzeszutek Wilk 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Sasha Levin 
Cc: Steven Rostedt 
Cc: Thomas Gleixner 
Cc: security@kernel.org 
Cc: xen-devel 
Link: http://lkml.kernel.org/r/4c6978476782160600471bd865b318db34c7b628.1438291540.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
[bwh: Backported to 3.2:
 - Adjust context
 - Drop comment changes in switch_mm()
 - Drop changes to get_segment_base() in arch/x86/kernel/cpu/perf_event.c
 - Open-code lockless_dereference(), smp_store_release(), on_each_cpu_mask()]
Signed-off-by: Ben Hutchings 
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li

x86: Require exact match for 'noxsave' command line option

2015-02-02T09:05:21+00:00

commit 2cd3949f702692cf4c5d05b463f19cd706a92dd3 upstream.

We have some very similarly named command-line options:

arch/x86/kernel/cpu/common.c:__setup("noxsave", x86_xsave_setup);
arch/x86/kernel/cpu/common.c:__setup("noxsaveopt", x86_xsaveopt_setup);
arch/x86/kernel/cpu/common.c:__setup("noxsaves", x86_xsaves_setup);

__setup() is designed to match options that take arguments, like
"foo=bar" where you would have:

	__setup("foo", x86_foo_func...);

The problem is that "noxsave" actually _matches_ "noxsaves" in
the same way that "foo" matches "foo=bar".  If you boot an old
kernel that does not know about "noxsaves" with "noxsaves" on the
command line, it will interpret the argument as "noxsave", which
is not what you want at all.

This makes the "noxsave" handler only return success when it finds
an *exact* match.

[ tglx: We really need to make __setup() more robust. ]

Signed-off-by: Dave Hansen 
Cc: Dave Hansen 
Cc: Fenghua Yu 
Cc: x86@kernel.org
Link: http://lkml.kernel.org/r/20141111220133.FE053984@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Zefan Li

x86/platform: Remove incorrect error message in x86_default_fixup_cpu_id()

2012-04-16T18:43:43+00:00

It's only called from amd.c:srat_detect_node(). The introduced
condition for calling the fixup code is true for all AMD
multi-node processors, e.g. Magny-Cours and Interlagos. There we
have 2 NUMA nodes on one socket. Thus there are cores having
different numa-node-id but with equal phys_proc_id.

There is no point to print error messages in such a situation.

The confusing/misleading error message was introduced with
commit 64be4c1c2428e148de6081af235e2418e6a66dda ("x86: Add
x86_init platform override to fix up NUMA core numbering").

Remove the default fixup function (especially the error message)
and replace it by a NULL pointer check, move the
Numascale-specific condition for calling the fixup into the
fixup-function itself and slightly adapt the comment.

Signed-off-by: Andreas Herrmann 
Acked-by: Borislav Petkov 
Cc: 
Cc: 
Cc: 
Cc: 
Link: http://lkml.kernel.org/r/20120402160648.GR27684@alberich.amd.com
Signed-off-by: Ingo Molnar

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-03-29T21:28:26+00:00

Pull x86 updates from Ingo Molnar.

This touches some non-x86 files due to the sanitized INLINE_SPIN_UNLOCK
config usage.

Fixed up trivial conflicts due to just header include changes (removing
headers due to cpu_idle() merge clashing with the  split).

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/apic/amd: Be more verbose about LVT offset assignments
  x86, tls: Off by one limit check
  x86/ioapic: Add io_apic_ops driver layer to allow interception
  x86/olpc: Add debugfs interface for EC commands
  x86: Merge the x86_32 and x86_64 cpu_idle() functions
  x86/kconfig: Remove CONFIG_TR=y from the defconfigs
  x86: Stop recursive fault in print_context_stack after stack overflow
  x86/io_apic: Move and reenable irq only when CONFIG_GENERIC_PENDING_IRQ=y
  x86/apic: Add separate apic_id_valid() functions for selected apic drivers
  locking/kconfig: Simplify INLINE_SPIN_UNLOCK usage
  x86/kconfig: Update defconfigs
  x86: Fix excessive MSR print out when show_msr is not specified

Merge tag 'bug-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

2012-03-24T17:08:39+00:00

Pull  cleanup from Paul Gortmaker:
 "The changes shown here are to unify linux's BUG support under the one
   file.  Due to historical reasons, we have some BUG code
  in bug.h and some in kernel.h -- i.e.  the support for BUILD_BUG in
  linux/kernel.h predates the addition of linux/bug.h, but old code in
  kernel.h wasn't moved to bug.h at that time.  As a band-aid, kernel.h
  was including  to pseudo link them.

  This has caused confusion[1] and general yuck/WTF[2] reactions.  Here
  is an example that violates the principle of least surprise:

      CC      lib/string.o
      lib/string.c: In function 'strlcat':
      lib/string.c:225:2: error: implicit declaration of function 'BUILD_BUG_ON'
      make[2]: *** [lib/string.o] Error 1
      $
      $ grep linux/bug.h lib/string.c
      #include 
      $

  We've included  for the BUG infrastructure and yet we
  still get a compile fail! [We've not kernel.h for BUILD_BUG_ON.] Ugh -
  very confusing for someone who is new to kernel development.

  With the above in mind, the goals of this changeset are:

  1) find and fix any include/*.h files that were relying on the
     implicit presence of BUG code.
  2) find and fix any C files that were consuming kernel.h and hence
     relying on implicitly getting some/all BUG code.
  3) Move the BUG related code living in kernel.h to 
  4) remove the asm/bug.h from kernel.h to finally break the chain.

  During development, the order was more like 3-4, build-test, 1-2.  But
  to ensure that git history for bisect doesn't get needless build
  failures introduced, the commits have been reorderd to fix the problem
  areas in advance.

	[1]  https://lkml.org/lkml/2012/1/3/90
	[2]  https://lkml.org/lkml/2012/1/17/414"

Fix up conflicts (new radeon file, reiserfs header cleanups) as per Paul
and linux-next.

* tag 'bug-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
  kernel.h: doesn't explicitly use bug.h, so don't include it.
  bug: consolidate BUILD_BUG_ON with other bug code
  BUG: headers with BUG/BUG_ON etc. need linux/bug.h
  bug.h: add include of it to various implicit C users
  lib: fix implicit users of kernel.h for TAINT_WARN
  spinlock: macroize assert_spin_locked to avoid bug.h dependency
  x86: relocate get/set debugreg fcns to include/asm/debugreg.

x86: Fix excessive MSR print out when show_msr is not specified

2012-03-23T08:55:00+00:00

Dave found:

| During bootup, I now have 162 messages like this..
| [    0.227346]  MSR0000001b: 00000000fee00900
| [    0.227465]  MSR00000021: 0000000000000001
| [    0.227584]  MSR0000002a: 00000000c1c81400
|
| commit 21c3fcf3e39353d4f21d50e257cc74f3204b1988 looks suspect.
| It claims that it will only print these out if show_msr= is
| passed, but that doesn't seem to be the case.

Fix it by changing to the version that checks the index.

Reported-and-tested-by: Dave Jones 
Signed-off-by: Yinghai Lu 
Link: http://lkml.kernel.org/r/1332477103-4595-1-git-send-email-yinghai@kernel.org
Signed-off-by: Ingo Molnar

Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-03-22T16:41:22+00:00

Pull x86/fpu changes from Ingo Molnar.

* 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  i387: Split up  into exported and internal interfaces
  i387: Uninline the generic FP helpers that we expose to kernel modules

Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2012-03-22T16:30:39+00:00

Pull x86/debug changes from Ingo Molnar.

* 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86: Fix section warnings
  x86-64: Fix CFI data for common_interrupt()
  x86: Properly _init-annotate NMI selftest code
  x86/debug: Fix/improve the show_msr= debug print out

x86: relocate get/set debugreg fcns to include/asm/debugreg.

2012-02-28T22:48:04+00:00

Since we already have a debugreg.h header file, move the
assoc. get/set functions to it.  In addition to it being the
logical home for them, it has a secondary advantage.  The
functions that are moved use BUG().  So we really need to
have linux/bug.h in scope.  But asm/processor.h is used about
600 times, vs. only about 15 for debugreg.h -- so adding bug.h
to the latter reduces the amount of time we'll be processing
it during a compile.

Signed-off-by: Paul Gortmaker 
Acked-by: Ingo Molnar 
CC: Thomas Gleixner 
CC: "H. Peter Anvin"

i387: Split up into exported and internal interfaces

2012-02-21T22:12:54+00:00

While various modules include  to get access to things we
actually *intend* for them to use, most of that header file was really
pretty low-level internal stuff that we really don't want to expose to
others.

So split the header file into two: the small exported interfaces remain
in , while the internal definitions that are only used by
core architecture code are now in .

The guiding principle for this was to expose functions that we export to
modules, and leave them in , while stuff that is used by
task switching or was marked GPL-only is in .

The fpu-internal.h file could be further split up too, especially since
arch/x86/kvm/ uses some of the remaining stuff for its module.  But that
kvm usage should probably be abstracted out a bit, and at least now the
internal FPU accessor functions are much more contained.  Even if it
isn't perhaps as contained as it _could_ be.

Signed-off-by: Linus Torvalds 
Link: http://lkml.kernel.org/r/alpine.LFD.2.02.1202211340330.5354@i5.linux-foundation.org
Signed-off-by: H. Peter Anvin