Follow other architectures for user fault handling.

Signed-off-by: Chung-Ling Tang <cltang@codesourcery.com>
Acked-by: Ley Foon Tan <lftan@altera.com>

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 <tiwai@suse.de>
Tested-by: Jan Engelhardt <jengelh@inai.de>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> # "s390 still compiles and boots"
Cc: linux-arch@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull one arch/nios2 fix from Ley Foon Tan:
 "Fix kuser trampoline address"

* tag 'nios2-fixes-v3.19-rc6' of git://git.rocketboards.org/linux-socfpga-next:
  nios2: fix kuser trampoline address

Pull module and param fixes from Rusty Russell:
 "Surprising number of fixes this merge window :(

  The first two are minor fallout from the param rework which went in
  this merge window.

  The next three are a series which fixes a longstanding (but never
  previously reported and unlikely , so no CC stable) race between
  kallsyms and freeing the init section.

  Finally, a minor cleanup as our module refcount will now be -1 during
  unload"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  module: make module_refcount() a signed integer.
  module: fix race in kallsyms resolution during module load success.
  module: remove mod arg from module_free, rename module_memfree().
  module_arch_freeing_init(): new hook for archs before module->module_init freed.
  param: fix uninitialized read with CONFIG_DEBUG_LOCK_ALLOC
  param: initialize store function to NULL if not available.

__kuser_sigtramp address should be 0x1044 instead of 0x1040.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

Nothing needs the module pointer any more, and the next patch will
call it from RCU, where the module itself might no longer exist.
Removing the arg is the safest approach.

This just codifies the use of the module_alloc/module_free pattern
which ftrace and bpf use.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Mikael Starvik <starvik@axis.com>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: x86@kernel.org
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: linux-cris-kernel@axis.com
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: nios2-dev@lists.rocketboards.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: sparclinux@vger.kernel.org
Cc: netdev@vger.kernel.org

Follow aa0d53260596 ("ia64: Use preempt_schedule_irq") and use
preempt_schedule_irq instead of enabling/disabling interrupts and
messing around with PREEMPT_ACTIVE in the nios2 low-level preemption
code ourselves. Also get rid of the now needless re-check for
TIF_NEED_RESCHED, preempt_schedule_irq will already take care of
rescheduling.

This also fixes the following build error when building with
CONFIG_PREEMPT:

arch/nios2/kernel/built-in.o: In function `need_resched':
arch/nios2/kernel/entry.S:374: undefined reference to `PREEMPT_ACTIVE'

Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Ley Foon Tan <lftan@altera.com>

This patch initializes the mmu field of the cpuinfo structure to the
value supplied by the devicetree.

Signed-off-by: Walter Goossens <waltergoossens@home.nl>
Acked-by: Ley Foon Tan <lftan@altera.com>

virtio wants to read bitwise types from userspace using get_user.  At the
moment this triggers sparse errors, since the value is passed through an
integer.

Fix that up using __force.

Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Ley Foon Tan <lftan@altera.com>

Running "make defconfig" currently fails for nios2:
    $ make ARCH=nios2 defconfig
    scripts/kconfig/conf --defconfig Kconfig
    ***
    *** Can't find default configuration "arch/nios2/defconfig"!
    ***
    make[1]: *** [defconfig] Error 1
    make: *** [defconfig] Error 2

Add a definition for KBUILD_DEFCONFIG to the nios2's main Makefile to enable
this make target.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Acked-by: Ley Foon Tan <lftan@altera.com>