Rebooting into a new kernel with kexec fails (system dies) if tried on
a machine that has no-execute support. Reason for this is that the so
called datamover code gets executed with DAT on (MMU is active) and
the page that contains the datamover is marked as non-executable.
Therefore when branching into the datamover an unexpected program
check happens and afterwards the machine is dead.

This can be simply avoided by disabling DAT, which also disables any
no-execute checks, just before the datamover gets executed.

In fact the first thing done by the datamover is to disable DAT. The
code in the datamover that disables DAT can be removed as well.

Thanks to Michael Holzheu and Gerald Schaefer for tracking this down.
Reviewed-by: NMichael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: NPhilipp Rudo <prudo@linux.vnet.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Fixes: 57d7f939 ("s390: add no-execute support")
Cc: <stable@vger.kernel.org> # v4.11+
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>

Reviewed-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Rename a couple of files to get rid of the "64" suffix.
"git blame" will still work.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Remove the file name from the comment at top of many files. In most
cases the file name was wrong anyway, so it's rather pointless.

Also unify the IBM copyright statement. We did have a lot of sightly
different statements and wanted to change them one after another
whenever a file gets touched. However that never happened. Instead
people start to take the old/"wrong" statements to use as a template
for new files.
So unify all of them in one go.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>

Use sigp order code defines in assembly code as well.
With this change all places that use sigp constants should
have been converted to use self describing defines instead
of directly using constants.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

The alignment is missing for various global symbols in s390 assembly code.
With a recent gcc and an instruction like stgrl this can lead to a
specification exception if the instruction uses such a mis-aligned address.

Specify the alignment explicitely and while add it define __ALIGN for s390
and use the ENTRY define to save some lines of code.
Signed-off-by: NJan Glauber <jang@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

In case of re-IPL and diag308 doesn't work we have to reset all devices
manually and wait synchronously that each reset finished.
This patch adds the necessary infrastucture and the first exploiter of it.

Subsystems that need to add a function that needs to be called at re-IPL
may register/unregister this function via

struct reset_call {
	struct reset_call *next;
	void (*fn)(void);
};

void register_reset_call(struct reset_call *reset);
void unregister_reset_call(struct reset_call *reset);

When the registered function get called the context is:

- all cpus beside the current one are stopped
- all machine checks and interrupts are disabled
- prefixing is disabled
- a default machine check handler is available for use

The registered functions may not take any locks are sleep.

For the common I/O layer part of this patch:

Introduce a reset_call css_reset that does the following:
- clear all subchannels
- perform a rchp on all channel paths and wait for the resulting
  machine checks
This replaces the calls to clear_all_subchannels() and
cio_reset_channel_paths() for kexec and ccw reipl. reipl_ccw_dev() now
uses reipl_find_schid() to determine the subchannel id for a given
device id.
Also remove cio_reset_channel_paths() and friends since they are not
needed anymore.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Huge s390 assembly files whitespace cleanup.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

Disable pseudo page fault handling before starting the new kernel and try
to use diag308 to reset the machine.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add kexec support for s390 architecture.

From: Milton Miller <miltonm@bga.com>

- Fix passing of first argument to relocate_kernel assembly.
- Fix Kconfig description.
- Remove wrong comment and comments that describe obvious things.
- Allow only KEXEC_TYPE_DEFAULT as image type -> dump not supported.
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>