The tricky part here is that task_pt_regs() on m68k works *only* for
process inside do_signal().  However, we need something much simpler -
pt_regs of a process inside do_signal() may be at different offsets
from the stack bottom, depending on the way we'd entered the kernel,
but for a task inside sys_execve() it *is* at constant offset.
Moreover, for a kernel thread about to become a userland process the
same location is also fine - setting sp to that will leave the kernel
stack pointer at the very bottom of the kernel stack when we finally
switch to userland.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

The stack frame "format" field needs to be explicitly set on thread creation
on ColdFire. For a normal long word aligned user stack pointer the frame
format is 0x4.

We were doing this for non-MMU ColdFire, but not for the case with MMU enabled.
So fix it so we always do it if targeting ColdFire.

The old code happend to rely on the stack frame format being inhereted from
the process calling exec. Furture changes means that may not always work,
so we really do want to set it explicitly.
Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

the only non-obvious part is that current_pt_regs() is really needed
here - task_pt_regs() is NULL for kernel threads; it's OK for ptrace
uses (the thing task_pt_regs() is intended for), but not for us.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and get rid of in-kernel syscalls in kernel_thread()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

same situation as with alpha and arm - only massage needed
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... and don't bother with syscall return path in case of kernel
threads.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

32bit wrapper is lost on that; 64bit one is *not*, since
we need to arrange for full pt_regs on stack when we call
sys_execve() and we need to load callee-saved ones from
there afterwards.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

get rid of sys_execve() wrapper, while we are at it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... no need to read current_thread_info()->task only to
feed it to task_thread_page() immediately afterwards.
Moreover, not using current_thread_info() at all ends
up with better assembler - we need a location very close
to the top of kernel stack page and it's actually better
to do or with 0x1fff, followed be subtracting a small
constant than and with ~0x1fff, followed by adding a large
one.  Both & and | would be a couple of insns (mvn lsr/mvn lsl
for |, a pair of bic for &), but the following addition
would cost a pair of add while the subtraction ends up
as a single sub.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Selected by __ARCH_WANT_SYS_EXECVE in unistd.h.  Requires
	* working current_pt_regs()
	* *NOT* doing a syscall-in-kernel kind of kernel_execve()
implementation.  Using generic kernel_execve() is fine.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

based mostly on arm and alpha versions.  Architectures can define
__ARCH_WANT_KERNEL_EXECVE and use it, provided that
	* they have working current_pt_regs(), even for kernel threads.
	* kernel_thread-spawned threads do have space for pt_regs
in the normal location.  Normally that's as simple as switching to
generic kernel_thread() and making sure that kernel threads do *not*
go through return from syscall path; call the payload from equivalent
of ret_from_fork if we are in a kernel thread (or just have separate
ret_from_kernel_thread and make copy_thread() use it instead of
ret_from_fork in kernel thread case).
	* they have ret_from_kernel_execve(); it is called after
successful do_execve() done by kernel_execve() and gets normal
pt_regs location passed to it as argument.  It's essentially
a longjmp() analog - it should set sp, etc. to the situation
expected at the return for syscall and go there.  Eventually
the need for that sucker will disappear, but that'll take some
surgery on kernel_thread() payloads.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Normally (and that's the default) it's just task_pt_regs(current).
However, if an architecture can optimize that, it can do so by
making a macro of its own available from asm/ptrace.h.  More
importantly, some architectures have task_pt_regs() working only
for traced tasks blocked on signal delivery.  current_pt_regs()
needs to work for *all* processes, so before those architectures
start using stuff relying on current_pt_regs() they'll need a
properly working variant.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Let architectures select GENERIC_KERNEL_THREAD and have their copy_thread()
treat NULL regs as "it came from kernel_thread(), sp argument contains
the function new thread will be calling and stack_size - the argument for
that function".  Switching the architectures begins shortly...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

we only use that to tell copy_thread() done by syscall from that
done by kernel_thread().  However, it's easier to do simply by
checking PF_KTHREAD in thread flags.

Merge sys_clone() guts for 32bit and 64bit, while we are at it...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... rather than duplicating that in sigframe setup code (and doing that
inconsistently, at that)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

... assuming it's needed to be done at all
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

most of the architectures don't and there's not a single
caller outside of core kernel.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

TIF_NOTIFY_RESUME will work in precisely the same way; all that
is achieved by TIF_IRET is appearing that there's some work to be
done, so we end up on the iret exit path.  Just use NOTIFY_RESUME.
And for execve() do that in 32bit start_thread(), not sys_execve()
itself.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Pull block fixes from Jens Axboe:
 "A small collection of driver fixes/updates and a core fix for 3.6.  It
  contains:

   - Bug fixes for mtip32xx, and support for new hardware (just addition
     of IDs).  They have been queued up for 3.7 for a few weeks as well.

   - rate-limit a failing command error message in block core.

   - A fix for an old cciss bug from Stephen.

   - Prevent overflow of partition count from Alan."

* 'for-linus' of git://git.kernel.dk/linux-block:
  cciss: fix handling of protocol error
  blk: add an upper sanity check on partition adding
  mtip32xx: fix user_buffer check in exec_drive_command
  mtip32xx: Remove dead code
  mtip32xx: Change printk to pr_xxxx
  mtip32xx: Proper reporting of write protect status on big-endian
  mtip32xx: Increase timeout for standby command
  mtip32xx: Handle NCQ commands during the security locked state
  mtip32xx: Add support for new devices
  block: rate-limit the error message from failing commands

Pull SuperH fixes from Paul Mundt.

* tag 'sh-for-linus' of git://github.com/pmundt/linux-sh:
  sh: Fix up TIF_NOTIFY_RESUME sans TIF_SIGPENDING handling.
  sh: pfc: Release spinlock in sh_pfc_gpio_request_enable() error path
  sh: intc: Fix up multi-evt irq association.

Pull rpmsg fix from Ohad Ben-Cohen:
 "A quick rpmsg fix from Fernando, fixing two buggy invocations of
  dma_free_coherent"

* tag 'rpmsg-3.6-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/ohad/rpmsg:
  rpmsg: fix dma_free_coherent dev parameter

Pull md fixes from NeilBrown:
 "3 fixes for md in 3.6.

  One reverts a recent patch which turns out to not be such a good idea.

  Other two fix minor bugs with the new (since 3.3) 'replacement' code
  and have been tagged for -stable."

* tag 'md-3.6-fixes' of git://neil.brown.name/md:
  md: make sure metadata is updated when spares are activated or removed.
  md/raid5: fix calculate of 'degraded' when a replacement becomes active.
  Revert "md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE."

Pull workqueue / powernow-k8 fix from Tejun Heo:
 "This is the fix for the bug where cpufreq/powernow-k8 was tripping
  BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a
  different CPU.

    https://bugzilla.kernel.org/show_bug.cgi?id=47301

  As discussed, the fix is now two parts - one to reimplement
  work_on_cpu() so that it doesn't create a new kthread each time and
  the actual fix which makes powernow-k8 use work_on_cpu() instead of
  performing manual migration.

  While pretty late in the merge cycle, both changes are on the safer
  side.  Jiri and I verified two existing users of work_on_cpu() and
  Duncan confirmed that the powernow-k8 fix survived about 18 hours of
  testing."

* 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  cpufreq/powernow-k8: workqueue user shouldn't migrate the kworker to another CPU
  workqueue: reimplement work_on_cpu() using system_wq

powernowk8_target() runs off a per-cpu work item and if the
cpufreq_policy->cpu is different from the current one, it migrates the
kworker to the target CPU by manipulating current->cpus_allowed.  The
function migrates the kworker back to the original CPU but this is
still broken.  Workqueue concurrency management requires the kworkers
to stay on the same CPU and powernowk8_target() ends up triggerring
BUG_ON(rq != this_rq()) in try_to_wake_up_local() if it contends on
fidvid_mutex and sleeps.

It is unclear why this bug is being reported now.  Duncan says it
appeared to be a regression of 3.6-rc1 and couldn't reproduce it on
3.5.  Bisection seemed to point to 63d95a91 "workqueue: use @pool
instead of @gcwq or @cpu where applicable" which is an non-functional
change.  Given that the reproduce case sometimes took upto days to
trigger, it's easy to be misled while bisecting.  Maybe something made
contention on fidvid_mutex more likely?  I don't know.

This patch fixes the bug by using work_on_cpu() instead if @pol->cpu
isn't the same as the current one.  The code assumes that
cpufreq_policy->cpu is kept online by the caller, which Rafael tells
me is the case.

stable: ed48ece2 ("workqueue: reimplement work_on_cpu() using
        system_wq") should be applied before this; otherwise, the
        behavior could be horrible.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Duncan <1i5t5.duncan@cox.net>
Tested-by: Duncan <1i5t5.duncan@cox.net>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: stable@vger.kernel.org
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=47301

The existing work_on_cpu() implementation is hugely inefficient.  It
creates a new kthread, execute that single function and then let the
kthread die on each invocation.

Now that system_wq can handle concurrent executions, there's no
advantage of doing this.  Reimplement work_on_cpu() using system_wq
which makes it simpler and way more efficient.

stable: While this isn't a fix in itself, it's needed to fix a
        workqueue related bug in cpufreq/powernow-k8.  AFAICS, this
        shouldn't break other existing users.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@vger.kernel.org

It isn't always necessary to update the metadata when spares are
removed as the presence-or-not of a spare isn't really important to
the integrity of an array.
Also activating a spare doesn't always require updating the metadata
as the update on 'recovery-completed' is usually sufficient.

However the introduction of 'replacement' devices have made these
transitions sometimes more important.  For example the 'Replacement'
flag isn't cleared until the original device is removed, so we need
to ensure a metadata update after that 'spare' is removed.

So set MD_CHANGE_DEVS whenever a spare is activated or removed, to
complement the current situation where it is set when a spare is added
or a device is failed (or a number of other less common situations).

This is suitable for -stable as out-of-data metadata could lead
to data corruption.
This is only relevant for 3.3 and later 9when 'replacement' as
introduced.

Cc: stable@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>

When a replacement device becomes active, we mark the device that it
replaces as 'faulty' so that it can subsequently get removed.
However 'calc_degraded' only pays attention to the primary device, not
the replacement, so the array appears to become degraded, which is
wrong.

So teach 'calc_degraded' to consider any replacement if a primary
device is faulty.

This is suitable for -stable as an incorrect 'degraded' value can
confuse md and could lead to data corruption.
This is only relevant for 3.3 and later.

Cc: stable@vger.kernel.org
Reported-by: Robin Hill <robin@robinhill.me.uk>
Reported-by: John Drescher <drescherjm@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>