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>

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>

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>

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>

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

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>

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>

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>

The spinlock code does not use NR_CPUS.
Compile tested using allyesconfig and allnoconfig.
Signed-off-by: NBjoern B. Brandenburg <bbb@cs.unc.edu>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Put it, as well as cpu_leds[] array, into sun4d_irq.c
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>

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

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

Don't clutter up the tree with sstate_blah() scattered all over the
place.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

We should always use prom_power_off().
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Three main things:

1) Make prober an arch initcall instead of using hard-coded invocation
   from paging_init()

2) Shrink table size, the fpu ident stuff was never used.

3) Use named struct initialized in table.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

While doing some easy cleanups on the sparc code I noticed that the
CONFIG_SUN4 code seems to be worse than the rest - there were some
"I don't know how it should work, but the current code definitely cannot
work." places.

And while I have seen people running Linux on machines like a
SPARCstation 5 a few years ago I don't recall having seen sun4
machines, even less ones running Linux.
Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

This driver is now limited to just doing the basic clock board and FHC
chip initialization and registering the platform devices for the
per-board LEDs, which are driven by the new LEDS_STARFIRE driver.

The IRQ register handling is already confined purely to the device
tree code.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

It does nothing.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

As suggested by Stephen Rothwell.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

All that remains is the EBUS DMA programming library for
sparc64.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

These have no dependencies on the EBUS probing layer, the clients
setup the registers and all of those details.  The EBUS DMA layer
just programs and manages the DMA controller found in EBUS.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Based largely upon a patch by Krzysztof Helt <krzysztof.h1@poczta.fm>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

No need for the 64-bit header version any more.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

In order to make this week I also had to add an include
of linux/dma-mapping.h to asm/pci_32.h because drivers/pci/pci.c
really depends upon getting this header somehow.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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

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

The individual SBUS IOMMU arch code now sets the IOMMU information
directly into the OF device objects.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Add a helper function that, given a bus of_device node, propagates
all iommu, stc, and host_controller values down to the child nodes.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

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