linux-stable.git/arch/x86/include/asm, branch linux-4.7.y

x86/apic: Get rid of apic_version[] array

2016-10-16T15:50:38+00:00

commit cff9ab2b291e64259d97add48fe073c081afe4e2 upstream.

The array has a size of MAX_LOCAL_APIC, which can be as large as 32k, so it
can consume up to 128k.

The array has been there forever and was never used for anything useful
other than a version mismatch check which was introduced in 2009.

There is no reason to store the version in an array. The kernel is not
prepared to handle different APIC versions anyway, so the real important
part is to detect a version mismatch and warn about it, which can be done
with a single variable as well.

[ tglx: Massaged changelog ]

Signed-off-by: Denys Vlasenko 
CC: Andy Lutomirski 
CC: Borislav Petkov 
CC: Brian Gerst 
CC: Mike Travis 
Link: http://lkml.kernel.org/r/20160913181232.30815-1-dvlasenk@redhat.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

x86/pkeys: Make protection keys an "eager" feature

2016-10-16T15:50:38+00:00

commit d4b05923f579c234137317cdf9a5eb69ddab76d1 upstream.

Our XSAVE features are divided into two categories: those that
generate FPU exceptions, and those that do not.  MPX and pkeys do
not generate FPU exceptions and thus can not be used lazily.  We
disable them when lazy mode is forced on.

We have a pair of masks to collect these two sets of features, but
XFEATURE_MASK_PKRU was added to the wrong mask: XFEATURE_MASK_LAZY.
Fix it by moving the feature to XFEATURE_MASK_EAGER.

Note: this only causes problem if you boot with lazy FPU mode
(eagerfpu=off) which is *not* the default.  It also only affects
hardware which is not currently publicly available.  It looks like
eager mode is going away, but we still need this patch applied
to any kernel that has protection keys and lazy mode, which is 4.6
through 4.8 at this point, and 4.9 if the lazy removal isn't sent
to Linus for 4.9.

Fixes: c8df40098451 ("x86/fpu, x86/mm/pkeys: Add PKRU xsave fields and data structures")
Signed-off-by: Dave Hansen 
Cc: Dave Hansen 
Link: http://lkml.kernel.org/r/20161007162342.28A49813@viggo.jf.intel.com
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

x86/init: Fix cr4_init_shadow() on CR4-less machines

2016-10-07T13:21:16+00:00

commit e1bfc11c5a6f40222a698a818dc269113245820e upstream.

cr4_init_shadow() will panic on 486-like machines without CR4.  Fix
it using __read_cr4_safe().

Reported-by: david@saggiorato.net
Signed-off-by: Andy Lutomirski 
Reviewed-by: Borislav Petkov 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Fixes: 1e02ce4cccdc ("x86: Store a per-cpu shadow copy of CR4")
Link: http://lkml.kernel.org/r/43a20f81fb504013bf613913dc25574b45336a61.1475091074.git.luto@kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

fix minor infoleak in get_user_ex()

2016-09-24T08:09:38+00:00

commit 1c109fabbd51863475cd12ac206bdd249aee35af upstream.

get_user_ex(x, ptr) should zero x on failure.  It's not a lot of a leak
(at most we are leaking uninitialized 64bit value off the kernel stack,
and in a fairly constrained situation, at that), but the fix is trivial,
so...

Signed-off-by: Al Viro 
[ This sat in different branch from the uaccess fixes since mid-August ]
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

x86/mm: Disable preemption during CR3 read+write

2016-09-07T06:34:42+00:00

commit 5cf0791da5c162ebc14b01eb01631cfa7ed4fa6e upstream.

There's a subtle preemption race on UP kernels:

Usually current->mm (and therefore mm->pgd) stays the same during the
lifetime of a task so it does not matter if a task gets preempted during
the read and write of the CR3.

But then, there is this scenario on x86-UP:

TaskA is in do_exit() and exit_mm() sets current->mm = NULL followed by:

 -> mmput()
 -> exit_mmap()
 -> tlb_finish_mmu()
 -> tlb_flush_mmu()
 -> tlb_flush_mmu_tlbonly()
 -> tlb_flush()
 -> flush_tlb_mm_range()
 -> __flush_tlb_up()
 -> __flush_tlb()
 ->  __native_flush_tlb()

At this point current->mm is NULL but current->active_mm still points to
the "old" mm.

Let's preempt taskA _after_ native_read_cr3() by taskB. TaskB has its
own mm so CR3 has changed.

Now preempt back to taskA. TaskA has no ->mm set so it borrows taskB's
mm and so CR3 remains unchanged. Once taskA gets active it continues
where it was interrupted and that means it writes its old CR3 value
back. Everything is fine because userland won't need its memory
anymore.

Now the fun part:

Let's preempt taskA one more time and get back to taskB. This
time switch_mm() won't do a thing because oldmm (->active_mm)
is the same as mm (as per context_switch()). So we remain
with a bad CR3 / PGD and return to userland.

The next thing that happens is handle_mm_fault() with an address for
the execution of its code in userland. handle_mm_fault() realizes that
it has a PTE with proper rights so it returns doing nothing. But the
CPU looks at the wrong PGD and insists that something is wrong and
faults again. And again. And one more time…

This pagefault circle continues until the scheduler gets tired of it and
puts another task on the CPU. It gets little difficult if the task is a
RT task with a high priority. The system will either freeze or it gets
fixed by the software watchdog thread which usually runs at RT-max prio.
But waiting for the watchdog will increase the latency of the RT task
which is no good.

Fix this by disabling preemption across the critical code section.

Signed-off-by: Sebastian Andrzej Siewior 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Rik van Riel 
Acked-by: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Mel Gorman 
Cc: Peter Zijlstra 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/1470404259-26290-1-git-send-email-bigeasy@linutronix.de
[ Prettified the changelog. ]
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86/microcode: Fix suspend to RAM with builtin microcode

2016-08-16T07:34:59+00:00

commit 4b703305d98bf7350d4b2953ee39a3aa2eeb1778 upstream.

Usually, after we have found the proper microcode blob for the current
machine, we stash it away for later use with save_microcode_in_initrd().

However, with builtin microcode which doesn't come from the initrd, we
don't call that function because CONFIG_BLK_DEV_INITRD=n and even if
set, we don't have a valid initrd.

In order to fix this, let's make save_microcode_in_initrd() an
fs_initcall which runs before rootfs_initcall() as this was the time it
was called previously through:

 rootfs_initcall(populate_rootfs)
 |-> free_initrd()
     |-> free_initrd_mem()
         |-> save_microcode_in_initrd()

Also, we make it run independently from initrd functionality being
present or not.

And since it is called in the microcode loader only now, we can also
make it static.

Reported-and-tested-by: Jim Bos 
Signed-off-by: Borislav Petkov 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/1465225850-7352-3-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

x86/cpu: Fix duplicated X86_BUG(9) macro

2016-07-09T12:06:06+00:00

cpufeatures.h currently defines X86_BUG(9) twice on 32-bit:

	#define X86_BUG_NULL_SEG        X86_BUG(9) /* Nulling a selector preserves the base */
	...
	#ifdef CONFIG_X86_32
	#define X86_BUG_ESPFIX          X86_BUG(9) /* "" IRET to 16-bit SS corrupts ESP/RSP high bits */
	#endif

I think what happened was that this added the X86_BUG_ESPFIX, but
in an #ifdef below most of the bugs:

	58a5aac53313 x86/entry/32: Introduce and use X86_BUG_ESPFIX instead of paravirt_enabled

Then this came along and added X86_BUG_NULL_SEG, but collided
with the earlier one that did the bug below the main block
defining all the X86_BUG()s.

	7a5d67048745 x86/cpu: Probe the behavior of nulling out a segment at boot time

Signed-off-by: Dave Hansen 
Acked-by: Andy Lutomirski 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Dave Hansen 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20160618001503.CEE1B141@viggo.jf.intel.com
Signed-off-by: Ingo Molnar

pvclock: Cleanup to remove function pvclock_get_nsec_offset

2016-06-27T13:12:14+00:00

Function __pvclock_read_cycles is short enough, so there is no need to
have another function pvclock_get_nsec_offset to calculate tsc delta.
It's better to combine it into function __pvclock_read_cycles.

Remove useless variables in function __pvclock_read_cycles.

Signed-off-by: Minfei Huang 
Signed-off-by: Paolo Bonzini

pvclock: Add CPU barriers to get correct version value

2016-06-27T13:12:14+00:00

Protocol for the "version" fields is: hypervisor raises it (making it
uneven) before it starts updating the fields and raises it again (making
it even) when it is done.  Thus the guest can make sure the time values
it got are consistent by checking the version before and after reading
them.

Add CPU barries after getting version value just like what function
vread_pvclock does, because all of callees in this function is inline.

Fixes: 502dfeff239e8313bfbe906ca0a1a6827ac8481b
Cc: stable@vger.kernel.org
Signed-off-by: Minfei Huang 
Signed-off-by: Paolo Bonzini

Merge branch 'akpm' (patches from Andrew)

2016-06-25T02:08:33+00:00

Merge misc fixes from Andrew Morton:
 "Two weeks worth of fixes here"

* emailed patches from Andrew Morton : (41 commits)
  init/main.c: fix initcall_blacklisted on ia64, ppc64 and parisc64
  autofs: don't get stuck in a loop if vfs_write() returns an error
  mm/page_owner: avoid null pointer dereference
  tools/vm/slabinfo: fix spelling mistake: "Ocurrences" -> "Occurrences"
  fs/nilfs2: fix potential underflow in call to crc32_le
  oom, suspend: fix oom_reaper vs. oom_killer_disable race
  ocfs2: disable BUG assertions in reading blocks
  mm, compaction: abort free scanner if split fails
  mm: prevent KASAN false positives in kmemleak
  mm/hugetlb: clear compound_mapcount when freeing gigantic pages
  mm/swap.c: flush lru pvecs on compound page arrival
  memcg: css_alloc should return an ERR_PTR value on error
  memcg: mem_cgroup_migrate() may be called with irq disabled
  hugetlb: fix nr_pmds accounting with shared page tables
  Revert "mm: disable fault around on emulated access bit architecture"
  Revert "mm: make faultaround produce old ptes"
  mailmap: add Boris Brezillon's email
  mailmap: add Antoine Tenart's email
  mm, sl[au]b: add __GFP_ATOMIC to the GFP reclaim mask
  mm: mempool: kasan: don't poot mempool objects in quarantine
  ...