linux.git/arch/powerpc/include/asm/pgtable.h, branch v4.13

powerpc/mm: Mark __init memory no-execute when STRICT_KERNEL_RWX=y

2017-07-18T09:54:24+00:00

Currently even with STRICT_KERNEL_RWX we leave the __init text marked
executable after init, which is bad.

Add a hook to mark it NX (no-execute) before we free it, and implement
it for radix and hash.

Note that we use __init_end as the end address, not _einittext,
because overlaps_kernel_text() uses __init_end, because there are
additional executable sections other than .init.text between
__init_begin and __init_end.

Tested on radix and hash with:

  0:mon> p $__init_begin
  *** 400 exception occurred

Fixes: 1e0fc9d1eb2b ("powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs")
Signed-off-by: Michael Ellerman

powerpc: port 64 bits pgtable_cache to 32 bits

2016-12-10T04:48:01+00:00

Today powerpc64 uses a set of pgtable_caches while powerpc32 uses
standard pages when using 4k pages and a single pgtable_cache
if using other size pages.

In preparation of implementing huge pages on the 8xx, this patch
replaces the specific powerpc32 handling by the 64 bits approach.

This is done by:
* moving 64 bits pgtable_cache_add() and pgtable_cache_init()
in a new file called init-common.c
* modifying pgtable_cache_init() to also handle the case
without PMD
* removing the 32 bits version of pgtable_cache_add() and
pgtable_cache_init()
* copying related header contents from 64 bits into both the
book3s/32 and nohash/32 header files

On the 8xx, the following cache sizes will be used:
* 4k pages mode:
- PGT_CACHE(10) for PGD
- PGT_CACHE(3) for 512k hugepage tables
* 16k pages mode:
- PGT_CACHE(6) for PGD
- PGT_CACHE(7) for 512k hugepage tables
- PGT_CACHE(3) for 8M hugepage tables

Signed-off-by: Christophe Leroy 
Reviewed-by: Aneesh Kumar K.V 
Signed-off-by: Scott Wood

powerpc/mm: check for irq disabled() only if DEBUG_VM is enabled

2016-07-26T23:19:19+00:00

We don't need to check this always.  The idea here is to capture the
wrong usage of find_linux_pte_or_hugepte and we can do that by
occasionally running with DEBUG_VM enabled.

Link: http://lkml.kernel.org/r/1464692688-6612-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V 
Cc: Michael Ellerman 
Cc: Benjamin Herrenschmidt 
Reviewed-by: Anshuman Khandual 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

arch: fix has_transparent_hugepage()

2016-05-20T02:12:14+00:00

I've just discovered that the useful-sounding has_transparent_hugepage()
is actually an architecture-dependent minefield: on some arches it only
builds if CONFIG_TRANSPARENT_HUGEPAGE=y, on others it's also there when
not, but on some of those (arm and arm64) it then gives the wrong
answer; and on mips alone it's marked __init, which would crash if
called later (but so far it has not been called later).

Straighten this out: make it available to all configs, with a sensible
default in asm-generic/pgtable.h, removing its definitions from those
arches (arc, arm, arm64, sparc, tile) which are served by the default,
adding #define has_transparent_hugepage has_transparent_hugepage to
those (mips, powerpc, s390, x86) which need to override the default at
runtime, and removing the __init from mips (but maybe that kind of code
should be avoided after init: set a static variable the first time it's
called).

Signed-off-by: Hugh Dickins 
Cc: "Kirill A. Shutemov" 
Cc: Andrea Arcangeli 
Cc: Andres Lagar-Cavilla 
Cc: Yang Shi 
Cc: Ning Qu 
Cc: Mel Gorman 
Cc: Konstantin Khlebnikov 
Acked-by: David S. Miller 
Acked-by: Vineet Gupta 		[arch/arc]
Acked-by: Gerald Schaefer 	[arch/s390]
Acked-by: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc: Make vmalloc_to_phys() public

2016-02-16T02:44:26+00:00

This makes vmalloc_to_phys() public as there will be another user
(KVM in-kernel VFIO acceleration) for it soon. As this new user
can be compiled as a module, this exports the symbol.

As a little optimization, this changes the helper to call
vmalloc_to_pfn() instead of vmalloc_to_page() as the size of the
struct page may not be power-of-two aligned which will make gcc use
multiply instructions instead of shifts.

Signed-off-by: Alexey Kardashevskiy 
Acked-by: Michael Ellerman 
Reviewed-by: David Gibson 
Signed-off-by: Paul Mackerras

powerpc/booke: Move nohash headers

2015-12-14T04:19:09+00:00

Move the booke related headers below booke/32 or booke/64

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: Move hash64 PTE bits from book3s/64/pgtable.h to hash.h

2015-12-14T04:19:08+00:00

This enables us to keep hash64 related bits together, and makes it easy
to follow.

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: Don't have generic headers introduce functions touching pte bits

2015-12-14T04:19:06+00:00

We are going to drop pte_common.h in the later patch. The idea is to
enable hash code not require to define all PTE bits. Having PTE bits
defined in pte_common.h made the code unnecessarily complex.

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: make a separate copy for book3s

2015-12-14T04:19:05+00:00

In this patch we do:
cp pgtable-ppc32.h book3s/32/pgtable.h
cp pgtable-ppc64.h book3s/64/pgtable.h

This enable us to do further changes to hash specific config.
We will change the page table format for 64bit hash in later patches.

Acked-by: Scott Wood 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman

powerpc/mm: Differentiate between hugetlb and THP during page walk

2015-10-12T04:30:09+00:00

We need to properly identify whether a hugepage is an explicit or
a transparent hugepage in follow_huge_addr(). We used to depend
on hugepage shift argument to do that. But in some case that can
result in wrong results. For ex:

On finding a transparent hugepage we set hugepage shift to PMD_SHIFT.
But we can end up clearing the thp pte, via pmdp_huge_get_and_clear.
We do prevent reusing the pfn page via the usage of
kick_all_cpus_sync(). But that happens after we updated the pte to 0.
Hence in follow_huge_addr() we can find hugepage shift set, but transparent
huge page check fail for a thp pte.

NOTE: We fixed a variant of this race against thp split in commit
691e95fd7396905a38d98919e9c150dbc3ea21a3
("powerpc/mm/thp: Make page table walk safe against thp split/collapse")

Without this patch, we may hit the BUG_ON(flags & FOLL_GET) in
follow_page_mask occasionally.

In the long term, we may want to switch ppc64 64k page size config to
enable CONFIG_ARCH_WANT_GENERAL_HUGETLB

Reported-by: David Gibson 
Signed-off-by: Aneesh Kumar K.V 
Signed-off-by: Michael Ellerman