linux.git/arch/s390/kernel/entry.S, branch v6.5

s390/entry: remove mcck clock

2023-07-03T09:19:42+00:00

In the past machine checks where accounted as irq time. With the conversion
to generic entry, it was decided to account machine checks to the current
context. The stckf at the beginning of the machine check handler and the
lowcore member is no longer required, therefore remove it.

Signed-off-by: Sven Schnelle 
Reviewed-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev

s390/entry: rework entering DAT-on mode on CPU restart

2023-07-03T09:19:40+00:00

Instead of enforcing PSW_MASK_DAT bit on previously stored
in lowcore restart_psw.mask use the PSW_KERNEL_BITS mask
(which contains PSW_MASK_DAT) directly.

As result, the PSW mask stored in lowcore is only used to
enter the CPU restart routine, while PSW_KERNEL_BITS is
used to enter the kernel code - similarily to commit
64ea2977add2 ("s390/mm: start kernel with DAT enabled").

Reviewed-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev

s390: consistently use .balign instead of .align

2023-06-28T11:57:09+00:00

The .align directive has inconsistent behavior across architectures. Use
.balign instead everywhere. This is a no-op for s390, but with this there
is no mix in using .align and .balign anymore.

Future code is supposed to use only .balign.

Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev

s390/entry: use SYM* macros instead of ENTRY(), etc.

2023-04-19T15:24:18+00:00

Consistently use the SYM* family of macros instead of the
deprecated ENTRY(), ENDPROC(), etc. family of macros.

Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: enable HAVE_ARCH_STACKLEAK

2023-04-04T16:34:56+00:00

Add support for the stackleak feature. Whenever the kernel returns to user
space the kernel stack is filled with a poison value.

Enabling this feature is quite expensive: e.g. after instrumenting the
getpid() system call function to have a 4kb stack the result is an
increased runtime of the system call by a factor of 3.

Reviewed-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/stack: use STACK_INIT_OFFSET where possible

2023-04-04T16:34:55+00:00

Make STACK_INIT_OFFSET also available for assembler code, and
use it everywhere instead of open-coding it at several places.

Reviewed-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/entry: rely on long-displacement facility

2023-04-04T16:34:54+00:00

Since commit 4efd417f298b ("s390: raise minimum supported machine
generation to z10"), the long-displacement facility is assumed and
required for the kernel. Clean up a couple of places in the entry code,
where long-displacement could be used directly instead of using a base
register.

However, there are still a few other places where a base register has
to be used to extend short-displacement for the second lowcore page
access. Notably, boot/head.S still has to be built for z900, and in
mcck_int_handler, spt and lbear, which don't have long-displacements,
but need to access save areas at the second lowcore page.

Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/bp: remove __bpon()

2023-03-13T08:16:42+00:00

There is no point in changing branch prediction state of a cpu shortly
before it enters stop state. Therefore remove __bpon().

Acked-by: Alexander Gordeev 
Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/bp: remove TIF_ISOLATE_BP

2023-03-13T08:16:42+00:00

TIF_ISOLATE_BP is unused since it was introduced with commit 6b73044b2b00
("s390: run user space and KVM guests with modified branch prediction").
Given that there is no use case remove it again.

Acked-by: Alexander Gordeev 
Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/bp: add missing BPENTER to program check handler

2023-03-13T08:16:42+00:00

When leaving interpretive execution because of a program check BPENTER
should be called like it is done on interrupt exit as well.

Acked-by: Alexander Gordeev 
Reviewed-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik