linux-toradex.git/arch/xtensa/mm, branch v4.4.26

xtensa: fix preemption in {clear,copy}_user_highpage

2016-04-12T16:08:55+00:00

commit a67cc9aa2dfc6e66addf240bbd79e16e01565e81 upstream.

Disabling pagefault makes little sense there, preemption disabling is
what was meant.

Signed-off-by: Max Filippov 
Signed-off-by: Greg Kroah-Hartman

xtensa: count software page fault perf events

2015-08-17T04:33:26+00:00

Signed-off-by: Max Filippov

mm/fault, arch: Use pagefault_disable() to check for disabled pagefaults in the handler

2015-05-19T06:39:15+00:00

Introduce faulthandler_disabled() and use it to check for irq context and
disabled pagefaults (via pagefault_disable()) in the pagefault handlers.

Please note that we keep the in_atomic() checks in place - to detect
whether in irq context (in which case preemption is always properly
disabled).

In contrast, preempt_disable() should never be used to disable pagefaults.
With !CONFIG_PREEMPT_COUNT, preempt_disable() doesn't modify the preempt
counter, and therefore the result of in_atomic() differs.
We validate that condition by using might_fault() checks when calling
might_sleep().

Therefore, add a comment to faulthandler_disabled(), describing why this
is needed.

faulthandler_disabled() and pagefault_disable() are defined in
linux/uaccess.h, so let's properly add that include to all relevant files.

This patch is based on a patch from Thomas Gleixner.

Reviewed-and-tested-by: Thomas Gleixner 
Signed-off-by: David Hildenbrand 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-7-git-send-email-dahi@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

sched/preempt, mm/kmap: Explicitly disable/enable preemption in kmap_atomic_*

2015-05-19T06:39:14+00:00

The existing code relies on pagefault_disable() implicitly disabling
preemption, so that no schedule will happen between kmap_atomic() and
kunmap_atomic().

Let's make this explicit, to prepare for pagefault_disable() not
touching preemption anymore.

Reviewed-and-tested-by: Thomas Gleixner 
Signed-off-by: David Hildenbrand 
Signed-off-by: Peter Zijlstra (Intel) 
Cc: David.Laight@ACULAB.COM
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: benh@kernel.crashing.org
Cc: bigeasy@linutronix.de
Cc: borntraeger@de.ibm.com
Cc: daniel.vetter@intel.com
Cc: heiko.carstens@de.ibm.com
Cc: herbert@gondor.apana.org.au
Cc: hocko@suse.cz
Cc: hughd@google.com
Cc: mst@redhat.com
Cc: paulus@samba.org
Cc: ralf@linux-mips.org
Cc: schwidefsky@de.ibm.com
Cc: yang.shi@windriver.com
Link: http://lkml.kernel.org/r/1431359540-32227-5-git-send-email-dahi@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar

vm: add VM_FAULT_SIGSEGV handling support

2015-01-29T18:51:32+00:00

The core VM already knows about VM_FAULT_SIGBUS, but cannot return a
"you should SIGSEGV" error, because the SIGSEGV case was generally
handled by the caller - usually the architecture fault handler.

That results in lots of duplication - all the architecture fault
handlers end up doing very similar "look up vma, check permissions, do
retries etc" - but it generally works.  However, there are cases where
the VM actually wants to SIGSEGV, and applications _expect_ SIGSEGV.

In particular, when accessing the stack guard page, libsigsegv expects a
SIGSEGV.  And it usually got one, because the stack growth is handled by
that duplicated architecture fault handler.

However, when the generic VM layer started propagating the error return
from the stack expansion in commit fee7e49d4514 ("mm: propagate error
from stack expansion even for guard page"), that now exposed the
existing VM_FAULT_SIGBUS result to user space.  And user space really
expected SIGSEGV, not SIGBUS.

To fix that case, we need to add a VM_FAULT_SIGSEGV, and teach all those
duplicate architecture fault handlers about it.  They all already have
the code to handle SIGSEGV, so it's about just tying that new return
value to the existing code, but it's all a bit annoying.

This is the mindless minimal patch to do this.  A more extensive patch
would be to try to gather up the mostly shared fault handling logic into
one generic helper routine, and long-term we really should do that
cleanup.

Just from this patch, you can generally see that most architectures just
copied (directly or indirectly) the old x86 way of doing things, but in
the meantime that original x86 model has been improved to hold the VM
semaphore for shorter times etc and to handle VM_FAULT_RETRY and other
"newer" things, so it would be a good idea to bring all those
improvements to the generic case and teach other architectures about
them too.

Reported-and-tested-by: Takashi Iwai 
Tested-by: Jan Engelhardt 
Acked-by: Heiko Carstens  # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds

xtensa: nommu: clean up memory map dump

2014-10-21T09:28:58+00:00

noMMU configuration doesn't use special area for vmalloc allocations,
don't print it in the memory map.
PAGE_OFFSET is fixed to 0 in noMMU, use min_low_pfn and max_low_pfn for
lowmem range display.
Make all XCHAL_KSEG_* constants unsigned long for consistency with other
addresses.

Signed-off-by: Max Filippov

xtensa: nommu: reserve memory below PLATFORM_DEFAULT_MEM_START

2014-10-21T09:28:57+00:00

Memory accounting code can't handle pages below
PLATFORM_DEFAULT_MEM_START. Reserve those pages if they exist.
When PLATFORM_DEFAULT_MEM_START is zero reserve one page at address 0 to
make sure that successfull memory allocations don't return NULL.

Signed-off-by: Max Filippov

xtensa: nommu: don't build most of the cache flushing code

2014-10-21T09:28:50+00:00

Most cache flushing code is only relevant for MMU. Don't build it for
nommu configuration.

Signed-off-by: Max Filippov

xtensa: support highmem in aliasing cache flushing code

2014-08-14T07:59:23+00:00

Use __flush_invalidate_dcache_page_alias with alias set to color of the
page physical address instead of __flush_invalidate_dcache_page: this
works for high memory pages and mapping/unmapping to the TLBTEMP area is
virtually free.

Allow building configurations with aliasing cache and highmem enabled.

Signed-off-by: Max Filippov

xtensa: support aliasing cache in kmap

2014-08-14T07:59:22+00:00

Define ARCH_PKMAP_COLORING and provide corresponding macro definitions
on cores with aliasing data cache.

Instead of single last_pkmap_nr maintain an array last_pkmap_nr_arr of
pkmap counters for each page color. Make sure that kmap maps physical
page at virtual address with color matching its physical address.

Signed-off-by: Max Filippov