linux-stable.git/arch, branch v4.1.3

arm64: vdso: work-around broken ELF toolchains in Makefile

2015-07-21T17:10:03+00:00

commit 6f1a6ae87c0c60d7c462ef8fd071f291aa7a9abb upstream.

When building the kernel with a bare-metal (ELF) toolchain, the -shared
option may not be passed down to collect2, resulting in silent corruption
of the vDSO image (in particular, the DYNAMIC section is omitted).

The effect of this corruption is that the dynamic linker fails to find
the vDSO symbols and libc is instead used for the syscalls that we
intended to optimise (e.g. gettimeofday). Functionally, there is no
issue as the sigreturn trampoline is still intact and located by the
kernel.

This patch fixes the problem by explicitly passing -shared to the linker
when building the vDSO.

Reported-by: Szabolcs Nagy 
Reported-by: James Greenlaigh 
Signed-off-by: Will Deacon 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: mm: Fix freeing of the wrong memmap entries with !SPARSEMEM_VMEMMAP

2015-07-21T17:10:03+00:00

commit b9bcc919931611498e856eae9bf66337330d04cc upstream.

The memmap freeing code in free_unused_memmap() computes the end of
each memblock by adding the memblock size onto the base.  However,
if SPARSEMEM is enabled then the value (start) used for the base
may already have been rounded downwards to work out which memmap
entries to free after the previous memblock.

This may cause memmap entries that are in use to get freed.

In general, you're not likely to hit this problem unless there
are at least 2 memblocks and one of them is not aligned to a
sparsemem section boundary.  Note that carve-outs can increase
the number of memblocks by splitting the regions listed in the
device tree.

This problem doesn't occur with SPARSEMEM_VMEMMAP, because the
vmemmap code deals with freeing the unused regions of the memmap
instead of requiring the arch code to do it.

This patch gets the memblock base out of the memblock directly when
computing the block end address to ensure the correct value is used.

Signed-off-by: Dave Martin 
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: entry: fix context tracking for el0_sp_pc

2015-07-21T17:10:03+00:00

commit 46b0567c851cf85d6ba6f23eef385ec9111d09bc upstream.

Commit 6c81fe7925cc4c42 ("arm64: enable context tracking") did not
update el0_sp_pc to use ct_user_exit, but this appears to have been
unintentional. In commit 6ab6463aeb5fbc75 ("arm64: adjust el0_sync so
that a function can be called") we made x0 available, and in the return
to userspace we call ct_user_enter in the kernel_exit macro.

Due to this, we currently don't correctly inform RCU of the user->kernel
transition, and may erroneously account for time spent in the kernel as
if we were in an extended quiescent state when CONFIG_CONTEXT_TRACKING
is enabled.

As we do record the kernel->user transition, a userspace application
making accesses from an unaligned stack pointer can demonstrate the
imbalance, provoking the following warning:

------------[ cut here ]------------
WARNING: CPU: 2 PID: 3660 at kernel/context_tracking.c:75 context_tracking_enter+0xd8/0xe4()
Modules linked in:
CPU: 2 PID: 3660 Comm: a.out Not tainted 4.1.0-rc7+ #8
Hardware name: ARM Juno development board (r0) (DT)
Call trace:
[] dump_backtrace+0x0/0x124
[] show_stack+0x10/0x1c
[] dump_stack+0x84/0xc8
[] warn_slowpath_common+0x98/0xd0
[] warn_slowpath_null+0x14/0x20
[] context_tracking_enter+0xd4/0xe4
[] preempt_schedule_irq+0xd4/0x114
[] el1_preempt+0x4/0x28
[] exit_files+0x38/0x4c
[] do_exit+0x430/0x978
[] do_group_exit+0x40/0xd4
[] get_signal+0x23c/0x4f4
[] do_signal+0x1ac/0x518
[] do_notify_resume+0x5c/0x68
---[ end trace 963c192600337066 ]---

This patch adds the missing ct_user_exit to the el0_sp_pc entry path,
correcting the context tracking for this case.

Signed-off-by: Mark Rutland 
Acked-by: Will Deacon 
Fixes: 6c81fe7925cc ("arm64: enable context tracking")
Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arm64: Do not attempt to use init_mm in reset_context()

2015-07-21T17:10:03+00:00

commit 565630d503ef24e44c252bed55571b3a0d68455f upstream.

After secondary CPU boot or hotplug, the active_mm of the idle thread is
&init_mm. The init_mm.pgd (swapper_pg_dir) is only meant for TTBR1_EL1
and must not be set in TTBR0_EL1. Since when active_mm == &init_mm the
TTBR0_EL1 is already set to the reserved value, there is no need to
perform any context reset.

Signed-off-by: Catalin Marinas 
Signed-off-by: Greg Kroah-Hartman

arc: fix use of uninitialized arc_pmu

2015-07-21T17:10:03+00:00

commit 7002f77541f877a5590615ceb3da32b114f14b62 upstream.

static arc_pmu in the arch/arc/kernel/perf_event.c is not initialized as
it's shadowed by a local variable of the same name in the
arc_pmu_device_probe.

Signed-off-by: Max Filippov 
Fixes: 03c94fcf954d "ARC: perf: make @arc_pmu static global"
Signed-off-by: Vineet Gupta 
Signed-off-by: Greg Kroah-Hartman

ARC: add compiler barrier to LLSC based cmpxchg

2015-07-21T17:10:03+00:00

commit d57f727264f1425a94689bafc7e99e502cb135b5 upstream.

When auditing cmpxchg call sites, Chuck noted that gcc was optimizing
away some of the desired LDs.

|	do {
|		new = old = *ipi_data_ptr;
|		new |= 1U << msg;
|	} while (cmpxchg(ipi_data_ptr, old, new) != old);

was generating to below

| 8015cef8:	ld         r2,[r4,0]  <-- First LD
| 8015cefc:	bset       r1,r2,r1
|
| 8015cf00:	llock      r3,[r4]  <-- atomic op
| 8015cf04:	brne       r3,r2,8015cf10
| 8015cf08:	scond      r1,[r4]
| 8015cf0c:	bnz        8015cf00
|
| 8015cf10:	brne       r3,r2,8015cf00  <-- Branch doesn't go to orig LD

Although this was fixed by adding a ACCESS_ONCE in this call site, it
seems safer (for now at least) to add compiler barrier to LLSC based
cmpxchg

Reported-by: Chuck Jordan 
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Vineet Gupta 
Signed-off-by: Greg Kroah-Hartman

ARC: add smp barriers around atomics per Documentation/atomic_ops.txt

2015-07-21T17:10:02+00:00

commit 2576c28e3f623ed401db7e6197241865328620ef upstream.

 - arch_spin_lock/unlock were lacking the ACQUIRE/RELEASE barriers
   Since ARCv2 only provides load/load, store/store and all/all, we need
   the full barrier

 - LLOCK/SCOND based atomics, bitops, cmpxchg, which return modified
   values were lacking the explicit smp barriers.

 - Non LLOCK/SCOND varaints don't need the explicit barriers since that
   is implicity provided by the spin locks used to implement the
   critical section (the spin lock barriers in turn are also fixed in
   this commit as explained above

Cc: Paul E. McKenney 
Acked-by: Peter Zijlstra (Intel) 
Signed-off-by: Vineet Gupta 
Signed-off-by: Greg Kroah-Hartman

sysfs: Create mountpoints with sysfs_create_mount_point

2015-07-21T17:10:01+00:00

commit f9bb48825a6b5d02f4cabcc78967c75db903dcdc upstream.

This allows for better documentation in the code and
it allows for a simpler and fully correct version of
fs_fully_visible to be written.

The mount points converted and their filesystems are:
/sys/hypervisor/s390/       s390_hypfs
/sys/kernel/config/         configfs
/sys/kernel/debug/          debugfs
/sys/firmware/efi/efivars/  efivarfs
/sys/fs/fuse/connections/   fusectl
/sys/fs/pstore/             pstore
/sys/kernel/tracing/        tracefs
/sys/fs/cgroup/             cgroup
/sys/kernel/security/       securityfs
/sys/fs/selinux/            selinuxfs
/sys/fs/smackfs/            smackfs

Acked-by: Greg Kroah-Hartman 
Signed-off-by: "Eric W. Biederman" 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: make vapics_in_nmi_mode atomic

2015-07-10T16:49:37+00:00

commit 42720138b06301cc8a7ee8a495a6d021c4b6a9bc upstream.

Writes were a bit racy, but hard to turn into a bug at the same time.
(Particularly because modern Linux doesn't use this feature anymore.)

Signed-off-by: Radim Krčmář 
[Actually the next patch makes it much, much easier to trigger the race
 so I'm including this one for stable@ as well. - Paolo]
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman

KVM: x86: properly restore LVT0

2015-07-10T16:49:37+00:00

commit db1385624c686fe99fe2d1b61a36e1537b915d08 upstream.

Legacy NMI watchdog didn't work after migration/resume, because
vapics_in_nmi_mode was left at 0.

Signed-off-by: Radim Krčmář 
Signed-off-by: Paolo Bonzini 
Signed-off-by: Greg Kroah-Hartman