linux-stable.git/arch/arm64/include/asm, branch v4.7.2

arm64: Enable workaround for Cavium erratum 27456 on thunderx-81xx

2016-07-07T17:35:21+00:00

Cavium erratum 27456 commit 104a0c02e8b1
("arm64: Add workaround for Cavium erratum 27456")
is applicable for thunderx-81xx pass1.0 SoC as well.
Adding code to enable to 81xx.

Signed-off-by: Ganapatrao Kulkarni 
Reviewed-by: Andrew Pinski 
Signed-off-by: Will Deacon

arm64: kernel: Save and restore UAO and addr_limit on exception entry

2016-07-07T14:55:37+00:00

If we take an exception while at EL1, the exception handler inherits
the original context's addr_limit and PSTATE.UAO values. To be consistent
always reset addr_limit and PSTATE.UAO on (re-)entry to EL1. This
prevents accidental re-use of the original context's addr_limit.

Based on a similar patch for arm from Russell King.

Cc:  # 4.6-
Acked-by: Will Deacon 
Reviewed-by: Mark Rutland 
Signed-off-by: James Morse 
Signed-off-by: Will Deacon

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
  ...

arm64: get rid of superfluous __GFP_REPEAT

2016-06-25T00:23:52+00:00

__GFP_REPEAT has a rather weak semantic but since it has been introduced
around 2.6.12 it has been ignored for low order allocations.

{pte,pmd,pud}_alloc_one{_kernel}, late_pgtable_alloc use PGALLOC_GFP for
__get_free_page (aka order-0).

pgd_alloc is slightly more complex because it allocates from pgd_cache
if PGD_SIZE != PAGE_SIZE and PGD_SIZE depends on the configuration
(CONFIG_ARM64_VA_BITS, PAGE_SHIFT and CONFIG_PGTABLE_LEVELS).

As per
config PGTABLE_LEVELS
	int
	default 2 if ARM64_16K_PAGES && ARM64_VA_BITS_36
	default 2 if ARM64_64K_PAGES && ARM64_VA_BITS_42
	default 3 if ARM64_64K_PAGES && ARM64_VA_BITS_48
	default 3 if ARM64_4K_PAGES && ARM64_VA_BITS_39
	default 3 if ARM64_16K_PAGES && ARM64_VA_BITS_47
	default 4 if !ARM64_64K_PAGES && ARM64_VA_BITS_48

we should have the following options

  CONFIG_ARM64_VA_BITS:48 CONFIG_PGTABLE_LEVELS:4 PAGE_SIZE:4k size:4096 pages:1
  CONFIG_ARM64_VA_BITS:48 CONFIG_PGTABLE_LEVELS:4 PAGE_SIZE:16k size:16 pages:1
  CONFIG_ARM64_VA_BITS:48 CONFIG_PGTABLE_LEVELS:3 PAGE_SIZE:64k size:512 pages:1
  CONFIG_ARM64_VA_BITS:47 CONFIG_PGTABLE_LEVELS:3 PAGE_SIZE:16k size:16384 pages:1
  CONFIG_ARM64_VA_BITS:42 CONFIG_PGTABLE_LEVELS:2 PAGE_SIZE:64k size:65536 pages:1
  CONFIG_ARM64_VA_BITS:39 CONFIG_PGTABLE_LEVELS:3 PAGE_SIZE:4k size:4096 pages:1
  CONFIG_ARM64_VA_BITS:36 CONFIG_PGTABLE_LEVELS:2 PAGE_SIZE:16k size:16384 pages:1

All of them fit into a single page (aka order-0).  This means that this
flag has never been actually useful here because it has always been used
only for PAGE_ALLOC_COSTLY requests.

Link: http://lkml.kernel.org/r/1464599699-30131-6-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko 
Acked-by: Will Deacon 
Cc: Catalin Marinas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

arm64: smp: Add function to determine if cpus are stuck in the kernel

2016-06-22T14:48:09+00:00

kernel/smp.c has a fancy counter that keeps track of the number of CPUs
it marked as not-present and left in cpu_park_loop(). If there are any
CPUs spinning in here, features like kexec or hibernate may release them
by overwriting this memory.

This problem also occurs on machines using spin-tables to release
secondary cores.
After commit 44dbcc93ab67 ("arm64: Fix behavior of maxcpus=N")
we bring all known cpus into the secondary holding pen, meaning this
memory can't be re-used by kexec or hibernate.

Add a function cpus_are_stuck_in_kernel() to determine if either of these
cases have occurred.

Signed-off-by: James Morse 
Acked-by: Mark Rutland 
Reviewed-by: Suzuki K Poulose 
Signed-off-by: Will Deacon

arm64: kgdb: Match pstate size with gdbserver protocol

2016-06-16T18:20:51+00:00

Current versions of gdb do not interoperate cleanly with kgdb on arm64
systems because gdb and kgdb do not use the same register description.
This patch modifies kgdb to work with recent releases of gdb (>= 7.8.1).

Compatibility with gdb (after the patch is applied) is as follows:

  gdb-7.6 and earlier  Ok
  gdb-7.7 series       Works if user provides custom target description
  gdb-7.8(.0)          Works if user provides custom target description
  gdb-7.8.1 and later  Ok

When commit 44679a4f142b ("arm64: KGDB: Add step debugging support") was
introduced it was paired with a gdb patch that made an incompatible
change to the gdbserver protocol. This patch was eventually merged into
the gdb sources:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=a4d9ba85ec5597a6a556afe26b712e878374b9dd

The change to the protocol was mostly made to simplify big-endian support
inside the kernel gdb stub. Unfortunately the gdb project released
gdb-7.7.x and gdb-7.8.0 before the protocol incompatibility was identified
and reversed:
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=bdc144174bcb11e808b4e73089b850cf9620a7ee

This leaves us in a position where kgdb still uses the no-longer-used
protocol; gdb-7.8.1, which restored the original behaviour, was
released on 2014-10-29.

I don't believe it is possible to detect/correct the protocol
incompatiblity which means the kernel must take a view about which
version of the gdb remote protocol is "correct". This patch takes the
view that the original/current version of the protocol is correct
and that version found in gdb-7.7.x and gdb-7.8.0 is anomalous.

Signed-off-by: Daniel Thompson 
Signed-off-by: Will Deacon

arm64: spinlock: Ensure forward-progress in spin_unlock_wait

2016-06-15T10:23:14+00:00

Rather than wait until we observe the lock being free (which might never
happen), we can also return from spin_unlock_wait if we observe that the
lock is now held by somebody else, which implies that it was unlocked
but we just missed seeing it in that state.

Furthermore, in such a scenario there is no longer a need to write back
the value that we loaded, since we know that there has been a lock
hand-off, which is sufficient to publish any stores prior to the
unlock_wait because the ARm architecture ensures that a Store-Release
instruction is multi-copy atomic when observed by a Load-Acquire
instruction.

The litmus test is something like:

AArch64
{
0:X1=x; 0:X3=y;
1:X1=y;
2:X1=y; 2:X3=x;
}
 P0          | P1           | P2           ;
 MOV W0,#1   | MOV W0,#1    | LDAR W0,[X1] ;
 STR W0,[X1] | STLR W0,[X1] | LDR W2,[X3]  ;
 DMB SY      |              |              ;
 LDR W2,[X3] |              |              ;
exists
(0:X2=0 /\ 2:X0=1 /\ 2:X2=0)

where P0 is doing spin_unlock_wait, P1 is doing spin_unlock and P2 is
doing spin_lock.

Signed-off-by: Will Deacon

arm64: spinlock: fix spin_unlock_wait for LSE atomics

2016-06-15T08:51:36+00:00

Commit d86b8da04dfa ("arm64: spinlock: serialise spin_unlock_wait against
concurrent lockers") fixed spin_unlock_wait for LL/SC-based atomics under
the premise that the LSE atomics (in particular, the LDADDA instruction)
are indivisible.

Unfortunately, these instructions are only indivisible when used with the
-AL (full ordering) suffix and, consequently, the same issue can
theoretically be observed with LSE atomics, where a later (in program
order) load can be speculated before the write portion of the atomic
operation.

This patch fixes the issue by performing a CAS of the lock once we've
established that it's unlocked, in much the same way as the LL/SC code.

Fixes: d86b8da04dfa ("arm64: spinlock: serialise spin_unlock_wait against concurrent lockers")
Signed-off-by: Will Deacon

arm64: spinlock: order spin_{is_locked,unlock_wait} against local locks

2016-06-15T08:51:35+00:00

spin_is_locked has grown two very different use-cases:

(1) [The sane case] API functions may require a certain lock to be held
    by the caller and can therefore use spin_is_locked as part of an
    assert statement in order to verify that the lock is indeed held.
    For example, usage of assert_spin_locked.

(2) [The insane case] There are two locks, where a CPU takes one of the
    locks and then checks whether or not the other one is held before
    accessing some shared state. For example, the "optimized locking" in
    ipc/sem.c.

In the latter case, the sequence looks like:

  spin_lock(&sem->lock);
  if (!spin_is_locked(&sma->sem_perm.lock))
    /* Access shared state */

and requires that the spin_is_locked check is ordered after taking the
sem->lock. Unfortunately, since our spinlocks are implemented using a
LDAXR/STXR sequence, the read of &sma->sem_perm.lock can be speculated
before the STXR and consequently return a stale value.

Whilst this hasn't been seen to cause issues in practice, PowerPC fixed
the same issue in 51d7d5205d33 ("powerpc: Add smp_mb() to
arch_spin_is_locked()") and, although we did something similar for
spin_unlock_wait in d86b8da04dfa ("arm64: spinlock: serialise
spin_unlock_wait against concurrent lockers") that doesn't actually take
care of ordering against local acquisition of a different lock.

This patch adds an smp_mb() to the start of our arch_spin_is_locked and
arch_spin_unlock_wait routines to ensure that the lock value is always
loaded after any other locks have been taken by the current CPU.

Reported-by: Peter Zijlstra 
Signed-off-by: Will Deacon

arm64: move {PAGE,CONT}_SHIFT into Kconfig

2016-06-03T09:57:18+00:00

In some cases (e.g. the awk for CONFIG_RANDOMIZE_TEXT_OFFSET) we would
like to make use of PAGE_SHIFT outside of code that can include the
usual header files.

Add a new CONFIG_ARM64_PAGE_SHIFT for this, likewise with
ARM64_CONT_SHIFT for consistency.

Signed-off-by: Mark Rutland 
Cc: Ard Biesheuvel 
Cc: Catalin Marinas 
Cc: Sudeep Holla 
Cc: Will Deacon 
Signed-off-by: Will Deacon