linux-stable.git/arch/s390/kernel/head.S, branch linux-4.2.y

s390: remove 31 bit support

2015-03-25T10:49:33+00:00

Remove the 31 bit support in order to reduce maintenance cost and
effectively remove dead code. Since a couple of years there is no
distribution left that comes with a 31 bit kernel.

The 31 bit kernel also has been broken since more than a year before
anybody noticed. In addition I added a removal warning to the kernel
shown at ipl for 5 minutes: a960062e5826 ("s390: add 31 bit warning
message") which let everybody know about the plan to remove 31 bit
code. We didn't get any response.

Given that the last 31 bit only machine was introduced in 1999 let's
remove the code.
Anybody with 31 bit user space code can still use the compat mode.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: add z13 code generation support

2015-01-22T11:15:57+00:00

Allow to generate code that only runs on z13 machines.

Signed-off-by: Martin Schwidefsky

s390/head.s: use zero as address for stfl

2014-09-25T08:52:06+00:00

The architecture suggests to use address 0 as parameter for stfl,
to allow for future extensions. Using __LC_STFL_FAC_LIST (0x200)
shows which address is used, but might be not future proof.

Signed-off-by: Christian Borntraeger 
Signed-off-by: Martin Schwidefsky

s390: require mvcos facility, not tod clock steering facility

2014-07-16T08:48:09+00:00

Inlined uaccess functions require the mvcos facility (bit 27), not the tod
clock steering facility (bit 28) for z10 and newer machines.

Signed-off-by: David Hildenbrand 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/facilities: remove extract-cpu-time facility check

2014-05-28T08:38:50+00:00

Remove the check for the extract-cpu-time facility within early startup
code. Both kernel and user space work if the facility is not installed.

The vdso code has a run time check if the ectg is available. Besides that
there is no known user.

Reported-by: Christian Borntraeger 
Acked-by: Christian Borntraeger 
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: require mvcos facility for z10 and newer machines

2014-05-27T08:26:05+00:00

With inlined uaccess functions we always need the mvcos facility.
Checking at each inline place if mvcos is available would make the
inlining of get_user/put_user pointless.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/bitops: optimize set_bit() for constant values

2013-10-24T15:16:53+00:00

Since zEC12 we have the interlocked-access facility 2 which allows to
use the instructions ni/oi/xi to update a single byte in storage with
compare-and-swap semantics.
So change set_bit(), clear_bit() and change_bit() to generate such code
instead of a compare-and-swap loop (or using the load-and-* instruction
family), if possible.
This reduces the text segment by yet another 8KB (defconfig).

Alternatively the long displacement variants niy/oiy/xiy could have
been used, but the extended displacement field is usually not needed
and therefore would only increase the size of the text segment again.

Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390: add zEC12 code generation support

2012-11-23T10:14:31+00:00

Allow to generate code that only runs on zEC12 machines.

Also add a check which prevents the kernel to run on machines which
do not have any of the following new facilities installed:

- (48) decimal-floating-point zoned-conversion
- (49) execution-hint
- (49) load-and-trap
- (49) miscellaneous-instruction-extensions
- (49) processor-assist
- (50) constrained transactional-execution
- (73) transactional-execution

48, 49, 50 and 73 are the bit numbers of the facility indications for
each of the required facilities.

Note that we assume that user-space gets compiled with the same
compiler options, therefore we also test for a dfp facility even
if the kernel doesn't make use of it.

Signed-off-by: Heiko Carstens

s390: add support to start the kernel in 64 bit mode.

2012-10-09T12:16:58+00:00

Do the switch to z/Architecture (alias 64 bit) mode early in head.S.
If the machine is already running in 64 bit mode the sigp turns into
a nop. With this change it doesn't matter in which mode the kernel
is started.

Reviewd-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky

s390/comments: unify copyright messages and remove file names

2012-07-20T09:15:04+00:00

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: Heiko Carstens