Pull more parisc updates from Helge Deller:

 - fix boot failure of 64-bit kernel. It got broken by the unwind
   optimization commit in merge window.

 - fix 64-bit userspace support (static 64-bit applications only, e.g.
   we don't yet have 64-bit userspace support in glibc).

 - consolidate unwind initialization code.

 - add machine model description to stack trace.

* 'parisc-4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Add hardware description to stack traces
  parisc: Fix boot failure of 64-bit kernel
  parisc: Consolidate unwind initialization calls
  parisc: Update comments in syscall.S regarding wide userland
  parisc: Fix ptraced 64-bit applications to call 64-bit syscalls
  parisc: Restore possibility to execute 64-bit applications

Commit c8921d72e390 ("parisc: Fix and improve kernel stack unwinding")
broke booting of 64-bit kernels. On 64-bit kernels function pointers are
actually function descriptors which require dereferencing. In this patch
we instead declare functions in assembly code which are referenced from
C-code as external data pointers with the ENTRY() macro and thus can use
a simple external reference to the functions.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: c8921d72e390 ("parisc: Fix and improve kernel stack unwinding")

Signed-off-by: Helge Deller <deller@gmx.de>

Executing 64-bit applications was broken. This patch restores this
support and cleans up some code paths.

Signed-off-by: Helge Deller <deller@gmx.de>

Pull parisc updates from Helge Deller:

 - parisc now uses the generic dma_noncoherent_ops implementation
   (Christoph Hellwig)

 - further memory barrier and spinlock improvements (John David Anglin)

 - prepare removal of current_text_addr() functions (Nick Desaulniers)

 - improve kernel stack unwinding on parisc (me)

 - drop ENOTSUP which was defined on parisc only (me)

* 'parisc-4.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Fix and improve kernel stack unwinding
  parisc: Remove unnecessary barriers from spinlock.h
  parisc: Remove ordered stores from syscall.S
  parisc: prefer _THIS_IP_ and _RET_IP_ statement expressions
  parisc: Add HAVE_REGS_AND_STACK_ACCESS_API feature
  parisc: Drop architecture-specific ENOTSUP define
  parisc: use generic dma_noncoherent_ops
  parisc: always use flush_kernel_dcache_range for DMA cache maintainance
  parisc: merge pcx_dma_ops and pcxl_dma_ops

Pull locking/atomics update from Thomas Gleixner:
 "The locking, atomics and memory model brains delivered:

   - A larger update to the atomics code which reworks the ordering
     barriers, consolidates the atomic primitives, provides the new
     atomic64_fetch_add_unless() primitive and cleans up the include
     hell.

   - Simplify cmpxchg() instrumentation and add instrumentation for
     xchg() and cmpxchg_double().

   - Updates to the memory model and documentation"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (48 commits)
  locking/atomics: Rework ordering barriers
  locking/atomics: Instrument cmpxchg_double*()
  locking/atomics: Instrument xchg()
  locking/atomics: Simplify cmpxchg() instrumentation
  locking/atomics/x86: Reduce arch_cmpxchg64*() instrumentation
  tools/memory-model: Rename litmus tests to comply to norm7
  tools/memory-model/Documentation: Fix typo, smb->smp
  sched/Documentation: Update wake_up() & co. memory-barrier guarantees
  locking/spinlock, sched/core: Clarify requirements for smp_mb__after_spinlock()
  sched/core: Use smp_mb() in wake_woken_function()
  tools/memory-model: Add informal LKMM documentation to MAINTAINERS
  locking/atomics/Documentation: Describe atomic_set() as a write operation
  tools/memory-model: Make scripts executable
  tools/memory-model: Remove ACCESS_ONCE() from model
  tools/memory-model: Remove ACCESS_ONCE() from recipes
  locking/memory-barriers.txt/kokr: Update Korean translation to fix broken DMA vs. MMIO ordering example
  MAINTAINERS: Add Daniel Lustig as an LKMM reviewer
  tools/memory-model: Fix ISA2+pooncelock+pooncelock+pombonce name
  tools/memory-model: Add litmus test for full multicopy atomicity
  locking/refcount: Always allow checked forms
  ...

This patchset fixes and improves stack unwinding a lot:
1. Show backward stack traces with up to 30 callsites
2. Add callinfo to ENTRY_CFI() such that every assembler function will get an
   entry in the unwind table
3. Use constants instead of numbers in call_on_stack()
4. Do not depend on CONFIG_KALLSYMS to generate backtraces.
5. Speed up backtrace generation

Make sure you have this patch to GNU as installed:
https://sourceware.org/ml/binutils/2018-07/msg00474.html
Without this patch, unwind info in the kernel is often wrong for various
functions.

Signed-off-by: Helge Deller <deller@gmx.de>

Now that mb() is an instruction barrier, it will slow performance if we issue
unnecessary barriers.

The spinlock defines have a number of unnecessary barriers.  The __ldcw()
define is both a hardware and compiler barrier.  The mb() barriers in the
routines using __ldcw() serve no purpose.

The only barrier needed is the one in arch_spin_unlock().  We need to ensure
all accesses are complete prior to releasing the lock.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org # 4.0+
Signed-off-by: Helge Deller <deller@gmx.de>

Some parts of the HAVE_REGS_AND_STACK_ACCESS_API feature is needed for
the rseq syscall. This patch adds the most important parts, and as long
as we don't support kprobes, we should be fine.

Signed-off-by: Helge Deller <deller@gmx.de>

Switch to the generic noncoherent direct mapping implementation.

Fix sync_single_for_cpu to do skip the cache flush unless the transfer
is to the device to match the more tested unmap_single path which should
have the same cache coherency implications.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Helge Deller <deller@gmx.de>