Impact: fix crashes that can occur in NMI handlers, if their code is modified

Modifying code is something that needs special care. On SMP boxes,
if code that is being modified is also being executed on another CPU,
that CPU will have undefined results.

The dynamic ftrace uses kstop_machine to make the system act like a
uniprocessor system. But this does not address NMIs, that can still
run on other CPUs.

One approach to handle this is to make all code that are used by NMIs
not be traced. But NMIs can call notifiers that spread throughout the
kernel and this will be very hard to maintain, and the chance of missing
a function is very high.

The approach that this patch takes is to have the NMIs modify the code
if the modification is taking place. The way this works is that just
writing to code executing on another CPU is not harmful if what is
written is the same as what exists.

Two buffers are used: an IP buffer and a "code" buffer.

The steps that the patcher takes are:

 1) Put in the instruction pointer into the IP buffer
    and the new code into the "code" buffer.
 2) Set a flag that says we are modifying code
 3) Wait for any running NMIs to finish.
 4) Write the code
 5) clear the flag.
 6) Wait for any running NMIs to finish.

If an NMI is executed, it will also write the pending code.
Multiple writes are OK, because what is being written is the same.
Then the patcher must wait for all running NMIs to finish before
going to the next line that must be patched.

This is basically the RCU approach to code modification.

Thanks to Ingo Molnar for suggesting the idea, and to Arjan van de Ven
for his guidence on what is safe and what is not.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Latest mainline gives this section mismatch on sparc:

The function current_pc() references
the variable __init no_sun4u_here.
This is often because current_pc lacks a __init
annotation or the annotation of no_sun4u_here is wrong.

Since current_pc() is used only in early time, it is correct to
put it in .init section.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The latest mainline gives this section mismatch on sparc:

The function __devinit apc_probe() references
a variable __initdata apc_no_idle.
If apc_no_idle is only used by apc_probe then
annotate apc_no_idle with a matching annotation.

Since the commit 7e7e2f03,
apc_probe() is on __devinit so we have to correct apc_no_idle
which is referenced by this function.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This patch implements a new freezer subsystem in the control groups
framework.  It provides a way to stop and resume execution of all tasks in
a cgroup by writing in the cgroup filesystem.

The freezer subsystem in the container filesystem defines a file named
freezer.state.  Writing "FROZEN" to the state file will freeze all tasks
in the cgroup.  Subsequently writing "RUNNING" will unfreeze the tasks in
the cgroup.  Reading will return the current state.

* Examples of usage :

   # mkdir /containers/freezer
   # mount -t cgroup -ofreezer freezer  /containers
   # mkdir /containers/0
   # echo $some_pid > /containers/0/tasks

to get status of the freezer subsystem :

   # cat /containers/0/freezer.state
   RUNNING

to freeze all tasks in the container :

   # echo FROZEN > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   FREEZING
   # cat /containers/0/freezer.state
   FROZEN

to unfreeze all tasks in the container :

   # echo RUNNING > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   RUNNING

This is the basic mechanism which should do the right thing for user space
task in a simple scenario.

It's important to note that freezing can be incomplete.  In that case we
return EBUSY.  This means that some tasks in the cgroup are busy doing
something that prevents us from completely freezing the cgroup at this
time.  After EBUSY, the cgroup will remain partially frozen -- reflected
by freezer.state reporting "FREEZING" when read.  The state will remain
"FREEZING" until one of these things happens:

	1) Userspace cancels the freezing operation by writing "RUNNING" to
		the freezer.state file
	2) Userspace retries the freezing operation by writing "FROZEN" to
		the freezer.state file (writing "FREEZING" is not legal
		and returns EIO)
	3) The tasks that blocked the cgroup from entering the "FROZEN"
		state disappear from the cgroup's set of tasks.

[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: export thaw_process]
Signed-off-by: NCedric Le Goater <clg@fr.ibm.com>
Signed-off-by: NMatt Helsley <matthltc@us.ibm.com>
Acked-by: NSerge E. Hallyn <serue@us.ibm.com>
Tested-by: NMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch series introduces a cgroup subsystem that utilizes the swsusp
freezer to freeze a group of tasks.  It's immediately useful for batch job
management scripts.  It should also be useful in the future for
implementing container checkpoint/restart.

The freezer subsystem in the container filesystem defines a cgroup file
named freezer.state.  Reading freezer.state will return the current state
of the cgroup.  Writing "FROZEN" to the state file will freeze all tasks
in the cgroup.  Subsequently writing "RUNNING" will unfreeze the tasks in
the cgroup.

* Examples of usage :

   # mkdir /containers/freezer
   # mount -t cgroup -ofreezer freezer  /containers
   # mkdir /containers/0
   # echo $some_pid > /containers/0/tasks

to get status of the freezer subsystem :

   # cat /containers/0/freezer.state
   RUNNING

to freeze all tasks in the container :

   # echo FROZEN > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   FREEZING
   # cat /containers/0/freezer.state
   FROZEN

to unfreeze all tasks in the container :

   # echo RUNNING > /containers/0/freezer.state
   # cat /containers/0/freezer.state
   RUNNING

This patch:

The first step in making the refrigerator() available to all
architectures, even for those without power management.

The purpose of such a change is to be able to use the refrigerator() in a
new control group subsystem which will implement a control group freezer.

[akpm@linux-foundation.org: fix sparc]
Signed-off-by: NCedric Le Goater <clg@fr.ibm.com>
Signed-off-by: NMatt Helsley <matthltc@us.ibm.com>
Acked-by: NPavel Machek <pavel@suse.cz>
Acked-by: NSerge E. Hallyn <serue@us.ibm.com>
Acked-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NNigel Cunningham <nigel@tuxonice.net>
Tested-by: NMatt Helsley <matthltc@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Revert the sparse irq changes in m68k/s390/sparc and just define
nr_irqs as NR_IRQS for those architectures.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Stephen Rothwell reported such build failures on m68k/sparc/s390:

> ERROR: "nr_irqs" [drivers/net/hamradio/baycom_ser_fdx.ko] undefined!
> ERROR: "nr_irqs" [drivers/net/3c59x.ko] undefined!

export nr_irqs on these architectures too.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

at this point nr_irqs is equal NR_IRQS

convert a few easy users from NR_IRQS to dynamic nr_irqs.

v2: according to Eric, we need to take care of arch without generic_hardirqs
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The SET_PERSONALITY macro is always called with a second argument of 0.
Remove the ibcs argument and the various tests to set the PER_SVR4
personality.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Signed-off-by: NRobert Richter <robert.richter@amd.com>

This requires three changes:

1) Remove !SPARC restriction in Kconfig.

2) Move Sparc specific serial drivers before 8250, so that serial
   console devices don't change names on us, even if 8250 finds
   devices.

3) Since the Sparc specific serial drivers try to use the
   same major/minor device namespace as 8250, some coordination
   is necessary.  Use the sunserial_*() layer routines to allocate
   minor number space within TTY_MAJOR when CONFIG_SPARC.

   This has no effect on other platforms.

Thanks to Josip Rodin for bringing up this issue and testing
plus debugging various revisions of this patch.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAlan Cox <alan@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/sparc/kernel/sun4d_smp.c: In function ‘smp4d_callin’:
arch/sparc/kernel/sun4d_smp.c:101: error: implicit declaration of function ‘notify_cpu_starting’
arch/sparc/kernel/sun4m_smp.c: In function ‘smp4m_callin’:
arch/sparc/kernel/sun4m_smp.c:74: error: implicit declaration of function ‘notify_cpu_starting’
Signed-off-by: NRobert Reif <reif@earthlink.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>

Here is an updated version of a patch I wrote 6 years ago
http://marc.info/?l=linux-sparc&m=103939103607617&w=2
that simplifies interrupt mask lookup.  It's main purpose
is to add VME bus support but it's really a cleanup of the mask code.
Signed-off-by: NRobert Reif <reif@earthlink.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

I have no SPARC compiler handy to verify, but it looks like this
is another file that doesn't need <linux/miscdevices.h> ...
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Unused.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It is only set, never used.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

No more users.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since the first argument is always NULL, the only side effect
is to disable the PROFILE_IRQ, so just do that directly.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Unused.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This is the only use of the clear_profile_irq() btfixup entry,
which just eats up lots of dead space on other platform types.

A subsequent commit will delete the other implementations and
the btfixup entry as well.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Always do the sbus_tid[] handling.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As noticed by Russell King, we were not setting this properly
to the number of entries, but rather the total size.

This results in the core dumping code allocating waayyyy too
much memory.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As noticed by Russell King, we were not setting this properly
to the number of entries, but rather the total size.

This results in the core dumping code allocating waayyyy too
much memory.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1) set_brkpt() is referenced by nothing and hasn't been used by anyone
   to my knowledge for many many years.  So just delete it.

2) add extern decl for do_sparc64_fault() in asm/pgtable_64.h
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

1) edge8 tables should be static
2) add vis_emul() extern decl. to asm/visasm.h
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As sparse warns, without this struct page pointer subtraction is
extremely expensive, and this is a pretty common operation in
fast paths.

With this define struct page becomes 64 bytes which makes for a
simple subtract and shift, instead of a costly divide or reciprocol
multiply.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This also takes care of a sparse warning as scons_pwroff's definition
point.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Lots of shadowed local variables and global_reg_snapshot[] needs
an extern declaration in asm/ptrace_64.h.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Mirror sparc64.  This will allow us to use early_param() on
sparc32 too.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This doesn't match the function pointer type it gets assigned
to.  Luckily, this was harmless.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It is just used as a parent to encapsulate two PBM objects.

But that layout is only really relevant and necessary for
psycho PCI controllers, which unlike all the others share
a single IOMMU instance between sibling PCI busses.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Otherwise we get refcount problems.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>