.fault now can retry.  The retry can break state machine of .fault.  In
filemap_fault, if page is miss, ra->mmap_miss is increased.  In the second
try, since the page is in page cache now, ra->mmap_miss is decreased.  And
these are done in one fault, so we can't detect random mmap file access.

Add a new flag to indicate .fault is tried once.  In the second try, skip
ra->mmap_miss decreasing.  The filemap_fault state machine is ok with it.

I only tested x86, didn't test other archs, but looks the change for other
archs is obvious, but who knows :)
Signed-off-by: NShaohua Li <shaohua.li@fusionio.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit d065bd81
(mm: retry page fault when blocking on disk transfer) and
commit 37b23e05
(x86,mm: make pagefault killable)

The above commits introduced changes into the x86 pagefault handler
for making the page fault handler retryable as well as killable.

These changes reduce the mmap_sem hold time, which is crucial
during OOM killer invocation.

Port these changes to microblaze.
Signed-off-by: NKautuk Consul <consul.kautuk@gmail.com>

Disintegrate asm/system.h for Microblaze.  Not compiled.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
cc: microblaze-uclinux@itee.uq.edu.au

Warning log:
CHECK   arch/microblaze/mm/fault.c
arch/microblaze/mm/fault.c:51:6: warning: incorrect type in initializer (different address spaces)
arch/microblaze/mm/fault.c:51:6:    expected unknown type 2const [noderef] *__gu_addr<asn:1>
arch/microblaze/mm/fault.c:51:6:    got unsigned int *<noident>
arch/microblaze/mm/fault.c:68:6: warning: symbol 'bad_page_fault' was not declared. Should it be static?
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Kgdb uses brki r16, 0x18 instruction to call
low level _debug_exception function which save
current state to pt_regs and call microblaze_kgdb_break
function. _debug_exception should be called only from
the kernel space. User space calling is not supported
because user application debugging uses different handling.

pt_regs_to_gdb_regs loads additional special registers
which can't be changed

 * Enable KGDB in Kconfig
 * Remove ancient not-tested KGDB support
 * Remove ancient _debug_exception code from entry.S

Only MMU KGDB support is supported.
Signed-off-by: NMichal Simek <monstr@monstr.eu>
CC: Jason Wessel <jason.wessel@windriver.com>
CC: John Williams <john.williams@petalogix.com>
CC: Edgar E. Iglesias <edgar.iglesias@petalogix.com>
CC: linux-kernel@vger.kernel.org
Acked-by: NJason Wessel <jason.wessel@windriver.com>

The label should be remove by
21e1c936

Warning message:
arch/microblaze/mm/fault.c: In function 'do_page_fault':
arch/microblaze/mm/fault.c:229: warning: label 'survive' defined but not used
Signed-off-by: NMichal Simek <monstr@monstr.eu>

As explained in commit 1c0fe6e3, we want to call the architecture independent
oom killer when getting an unexplained OOM from handle_mm_fault, rather than
simply killing current.

Cc: microblaze-uclinux@itee.uq.edu.au
Cc: Michal Simek <monstr@monstr.eu>
Cc: linux-arch@vger.kernel.org
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NMichal Simek <monstr@monstr.eu>

On the base on GCOV analytics is helpful to add likely/unlikely
macros.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

This patch add support for cases where load/store instruction
in put/get_user macro gets unaligned pointer to data and this
address is not valid. I prevent all cases which can failed.
I had to disable first stage of unaligned handler which is used
only for noMMU kernel and the whole work is done when interrupt
is enabled.
You have enable HW support for detect unaligned access in Microblaze.

This patch fixed three LTP tests:
getpeername01, getsockname01, socketpair01
Signed-off-by: NMichal Simek <monstr@monstr.eu>

Calling fixup when we are in kernel mode. This
prevent fault for copy_to/from_user. This fault
was find thanks to writev01/03/04 LTP tests.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

This allows the callers to now pass down the full set of FAULT_FLAG_xyz
flags to handle_mm_fault().  All callers have been (mechanically)
converted to the new calling convention, there's almost certainly room
for architectures to clean up their code and then add FAULT_FLAG_RETRY
when that support is added.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NMichal Simek <monstr@monstr.eu>