Looks like our L_PTE_S2_RDWR definition is slightly wrong,
and is actually write only (see ARM ARM Table B3-9, Stage 2 control
of access permissions). Didn't make a difference for normal pages,
as we OR the flags together, but I'm still wondering how it worked
for Stage-2 mapped devices, such as the GIC.

Brown paper bag time, again.
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <cdall@cs.columbia.edu>

KVM uses the stage-2 page tables and the Hyp page table format,
so we define the fields and page protection flags needed by KVM.

The nomenclature is this:
 - page_hyp:        PL2 code/data mappings
 - page_hyp_device: PL2 device mappings (vgic access)
 - page_s2:         Stage-2 code/data page mappings
 - page_s2_device:  Stage-2 device mappings (vgic access)
Reviewed-by: NWill Deacon <will.deacon@arm.com>
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Christoffer Dall <c.dall@virtualopensystems.com>

PROT_NONE mappings apply the page protection attributes defined by _P000
which translate to PAGE_NONE for ARM. These attributes specify an XN,
RDONLY pte that is inaccessible to userspace. However, on kernels
configured without support for domains, such a pte *is* accessible to
the kernel and can be read via get_user, allowing tasks to read
PROT_NONE pages via syscalls such as read/write over a pipe.

This patch introduces a new software pte flag, L_PTE_NONE, that is set
to identify faulting, present entries.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

For long-descriptor translation table formats, the ARMv7 architecture
defines the last two bits of the second- and third-level descriptors to
be:

	x0b	- Invalid
	01b	- Block (second-level), Reserved (third-level)
	11b	- Table (second-level), Page (third-level)

This allows us to define L_PTE_PRESENT as (3 << 0) and use this value to
create ptes directly. However, when determining whether a given pte
value is present in the low-level page table accessors, we only need to
check the least significant bit of the descriptor, allowing us to write
faulting, present entries which are required for PROT_NONE mappings.

This patch introduces L_PTE_VALID, which can be used to test whether a
pte should fault, and updates the low-level page table accessors
accordingly.
Signed-off-by: NWill Deacon <will.deacon@arm.com>

These have already been removed from the classic MMU in favour of
L_PTE_MT_* macros.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

This patch modifies the pgd/pmd/pte manipulation functions to support
the 3-level page table format. Since there is no need for an 'ext'
argument to cpu_set_pte_ext(), this patch conditionally defines a
different prototype for this function when CONFIG_ARM_LPAE.

The patch also introduces the L_PGD_SWAPPER flag to mark pgd entries
pointing to pmd tables pre-allocated in the swapper_pg_dir and avoid
trying to free them at run-time. This flag is 0 with the classic page
table format.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

This patch introduces the pgtable-3level*.h files with definitions
specific to the LPAE page table format (3 levels of page tables).

Each table is 4KB and has 512 64-bit entries. An entry can point to a
40-bit physical address. The young, write and exec software bits share
the corresponding hardware bits (negated). Other software bits use spare
bits in the PTE.

The patch also changes some variable types from unsigned long or int to
pteval_t or pgprot_t.
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>