commit 33692f27597fcab536d7cbbcc8f52905133e4aa7 upstream.

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>
[shengyong: Backport to 3.14
 - adjust context
 - ignore modification for arch nios2, because 3.14 does not support it
 - add SIGSEGV handling to powerpc/cell spu_fault.c, because 3.14 does not
   separate it to copro_fault.c
 - add SIGSEGV handling to mm/memory.c, because 3.14 does not separate it
   to gup.c
]
Signed-off-by: Sheng Yong <shengyong1@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Correct a typo causing the stack protector to be left enabled.
0xFFFFFFF -> 0xFFFFFFFF

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Some drivers check if readq/writeq functions are defined.
If not internal driver functions are used which cause
compilation failures.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Add missing param.h header because of HZ macro.
It is causing compilation failure:
In file included from include/linux/delay.h:14:0,
                    from drivers/clk/qcom/reset.c:18:
drivers/clk/qcom/reset.c: In function 'qcom_reset':
arch/microblaze/include/asm/delay.h:39:35: error: 'HZ'
 undeclared (first use in this function)

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Pull microblaze patches from Michal Simek:
 - add CCF support
 - fix BS=0 compilation
 - wire up defconfig
 - some minor cleanups and fixes

* tag 'microblaze-3.14-rc1' of git://git.monstr.eu/linux-2.6-microblaze:
  microblaze: Add missing v8.50.a version
  microblaze: Fix missing bracket in printk
  microblaze: Fix compilation error for BS=0
  microblaze: Disable stack protection from bootloader
  microblaze: Define read/write{b,w,l}_relaxed MMIO
  microblaze: timer: Do not initialized system timer twice
  microblaze: timer: Use generic sched_clock implementation
  microblaze: Add NOTES section to linker script
  microblaze: Add support for CCF
  microblaze: Simplify fcpu helper function
  microblaze/uapi: Use Kbuild logic to include <asm-generic/types.h>
  microblaze: Remove duplicate declarations of _stext[] and _etext[]
  microblaze: Remove _fdt_start casts
  microblaze: Wire up defconfig to mmu_defconfig

Add PVR value for MB 8.50.a.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

The error was introduced by the patch
"microblaze: Fix coding style issues"
(sha1: 6bd55f0bbaebb79b39e147aa864401fd0c94db82).

Error message:
arch/microblaze/kernel/setup.c: In function 'machine_early_init':
arch/microblaze/kernel/setup.c:177:3: error: 'pr_cont'
  undeclared (first use in this function)
arch/microblaze/kernel/setup.c:177:3: note: each undeclared
  identifier is reported only once for each function it appears in
arch/microblaze/kernel/setup.c:177:10: error: expected ';'
  before string constant
arch/microblaze/kernel/setup.c:177:33: error: expected statement
  before ')' token

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

This bug was introduced by:
"microblaze: Do not used hardcoded value in exception handler"
(sha1: 9f78d3b5ab97a22a7e836312c495804ee4bca4ab)

System without barrel shifter are pretty rare that's why
this bug has been fixed so late.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

Microblaze without MMU can use stack protection in bootloader
and kernel should clear this setting ASAP.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

More and more ARM specific drivers is using MMIO
readX/writeX_relaxed IO functions and Microblaze can
shared some drivers with ARM too.

This patch adds relaxed IO accessor macros
to prevent compilation failures.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>