commit 84fe6826c28f69d8708bd575faed7f75e6b6f57f upstream.

Page table entries on ARM64 are 64 bits, and some pte functions such as
pte_dirty return a bitwise-and of a flag with the pte value. If the
flag to be tested resides in the upper 32 bits of the pte, then we run
into the danger of the result being dropped if downcast.

For example:
	gather_stats(page, md, pte_dirty(*pte), 1);
where pte_dirty(*pte) is downcast to an int.

This patch adds a double logical invert to all the pte_ accessors to
ensure predictable downcasting.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
[steve.capper@linaro.org: rebased patch to leave pte_write alone to
allow for merge with 3.13 stable]
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 5044bad43ee573d0b6d90e3ccb7a40c2c7d25eb4 upstream.

Add DSB after icache flush to complete the cache maintenance operation.
The function __flush_icache_all() is used only for user space mappings
and an ISB is not required because of an exception return before executing
user instructions. An exception return would behave like an ISB.

Signed-off-by: Vinayak Kale <vkale@apm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 8e86f0b409a44193f1587e87b69c5dcf8f65be67 upstream.

Linux requires a number of atomic operations to provide full barrier
semantics, that is no memory accesses after the operation can be
observed before any accesses up to and including the operation in
program order.

On arm64, these operations have been incorrectly implemented as follows:

	// A, B, C are independent memory locations

	<Access [A]>

	// atomic_op (B)
1:	ldaxr	x0, [B]		// Exclusive load with acquire
	<op(B)>
	stlxr	w1, x0, [B]	// Exclusive store with release
	cbnz	w1, 1b

	<Access [C]>

The assumption here being that two half barriers are equivalent to a
full barrier, so the only permitted ordering would be A -> B -> C
(where B is the atomic operation involving both a load and a store).

Unfortunately, this is not the case by the letter of the architecture
and, in fact, the accesses to A and C are permitted to pass their
nearest half barrier resulting in orderings such as Bl -> A -> C -> Bs
or Bl -> C -> A -> Bs (where Bl is the load-acquire on B and Bs is the
store-release on B). This is a clear violation of the full barrier
requirement.

The simple way to fix this is to implement the same algorithm as ARMv7
using explicit barriers:

	<Access [A]>

	// atomic_op (B)
	dmb	ish		// Full barrier
1:	ldxr	x0, [B]		// Exclusive load
	<op(B)>
	stxr	w1, x0, [B]	// Exclusive store
	cbnz	w1, 1b
	dmb	ish		// Full barrier

	<Access [C]>

but this has the undesirable effect of introducing *two* full barrier
instructions. A better approach is actually the following, non-intuitive
sequence:

	<Access [A]>

	// atomic_op (B)
1:	ldxr	x0, [B]		// Exclusive load
	<op(B)>
	stlxr	w1, x0, [B]	// Exclusive store with release
	cbnz	w1, 1b
	dmb	ish		// Full barrier

	<Access [C]>

The simple observations here are:

  - The dmb ensures that no subsequent accesses (e.g. the access to C)
    can enter or pass the atomic sequence.

  - The dmb also ensures that no prior accesses (e.g. the access to A)
    can pass the atomic sequence.

  - Therefore, no prior access can pass a subsequent access, or
    vice-versa (i.e. A is strictly ordered before C).

  - The stlxr ensures that no prior access can pass the store component
    of the atomic operation.

The only tricky part remaining is the ordering between the ldxr and the
access to A, since the absence of the first dmb means that we're now
permitting re-ordering between the ldxr and any prior accesses.

From an (arbitrary) observer's point of view, there are two scenarios:

  1. We have observed the ldxr. This means that if we perform a store to
     [B], the ldxr will still return older data. If we can observe the
     ldxr, then we can potentially observe the permitted re-ordering
     with the access to A, which is clearly an issue when compared to
     the dmb variant of the code. Thankfully, the exclusive monitor will
     save us here since it will be cleared as a result of the store and
     the ldxr will retry. Notice that any use of a later memory
     observation to imply observation of the ldxr will also imply
     observation of the access to A, since the stlxr/dmb ensure strict
     ordering.

  2. We have not observed the ldxr. This means we can perform a store
     and influence the later ldxr. However, that doesn't actually tell
     us anything about the access to [A], so we've not lost anything
     here either when compared to the dmb variant.

This patch implements this solution for our barriered atomic operations,
ensuring that we satisfy the full barrier requirements where they are
needed.

Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull arm64 fix from Catalin Marinas:
 "Revert "arm64: Fix memory shareability attribute for ioremap_wc/cache"

  We noticed that it breaks ioremap (and earlyprintk) with 64K page
  configuration"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  Revert "arm64: Fix memory shareability attribute for ioremap_wc/cache"

This reverts commit 2f7dc6027522499582a520807cb9ffda589de47e.

The above commit breaks the mapping type for Device memory because
pgprot_default already contains a Normal memory type. pgprot_default is
also not initialised early enough for earlyprintk resulting in an
inconsistent memory mapping with 64K PAGE_SIZE configuration.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Will Deacon <will.deacon@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>

Pull Xen bugfixes from Konrad Rzeszutek Wilk:
 - Fix balloon driver for auto-translate guests (PVHVM, ARM) to not use
   scratch pages.
 - Fix block API header for ARM32 and ARM64 to have proper layout
 - On ARM when mapping guests, stick on PTE_SPECIAL
 - When using SWIOTLB under ARM, don't call swiotlb functions twice
 - When unmapping guests memory and if we fail, don't return pages which
   failed to be unmapped.
 - Grant driver was using the wrong address on ARM.

* tag 'stable/for-linus-3.13-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/balloon: Seperate the auto-translate logic properly (v2)
  xen/block: Correctly define structures in public headers on ARM32 and ARM64
  arm: xen: foreign mapping PTEs are special.
  xen/arm64: do not call the swiotlb functions twice
  xen: privcmd: do not return pages which we have failed to unmap
  XEN: Grant table address, xen_hvm_resume_frames, is a phys_addr not a pfn

On arm64 the dma_map_ops implementation is based on the swiotlb.
swiotlb-xen, used by default in dom0 on Xen, is also based on the
swiotlb.

Avoid calling into the default arm64 dma_map_ops functions from
xen_dma_map_page, xen_dma_unmap_page, xen_dma_sync_single_for_cpu, and
xen_dma_sync_single_for_device otherwise we end up calling into the
swiotlb twice.

When arm64 gets a non-swiotlb based implementation of dma_map_ops, we'll
probably have to reintroduce dma_map_ops calls in page-coherent.h.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: catalin.marinas@arm.com
CC: Will.Deacon@arm.com
CC: Ian.Campbell@citrix.com

Modify the value of PMD_SECT_PROT_NONE to match that of PTE_NONE. This
should have been in commit 3676f9ef5481 (Move PTE_PROT_NONE higher up).

Signed-off-by: Steve Capper <steve.capper@linaro.org>
Cc: <stable@vger.kernel.org> # 3.11+: 3676f9ef5481: arm64: Move PTE_PROT_NONE higher up
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Write-combine and cacheable mappings use Normal memory on arm64. On SMP
systems, the pte needs the shareability bit which is set in
pgprot_default. Use this for defining PROT_DEFAULT used by ioremap_wc
and ioremap_cache (Device memory is shareable by default, does not need
additional attributes).

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

PTE_PROT_NONE means that a pte is present but does not have any
read/write attributes. However, setting the memory type like
pgprot_writecombine() is allowed and such bits overlap with
PTE_PROT_NONE. This causes mmap/munmap issues in drivers that change the
vma->vm_pg_prot on PROT_NONE mappings.

This patch reverts the PTE_FILE/PTE_PROT_NONE shift in commit
59911ca4325d (ARM64: mm: Move PTE_PROT_NONE bit) and moves PTE_PROT_NONE
together with the other software bits.

Signed-off-by: Steve Capper <steve.capper@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Steve Capper <steve.capper@linaro.org>
Cc: <stable@vger.kernel.org> # 3.11+