s390/mcck: cleanup user process termination path

If a machine check interrupt hits while user process is
running __s390_handle_mcck() helper function is called
directly from the interrupt handler an

s390/mcck: cleanup user process termination path

If a machine check interrupt hits while user process is
running __s390_handle_mcck() helper function is called
directly from the interrupt handler and terminates the
current process by calling make_task_dead() routine.

The make_task_dead() is not allowed to be called from
interrupt context which forces the machine check handler
switch to the kernel stack and enable local interrupts
first.

The __s390_handle_mcck() could also be called to service
pending work, but this time from the external interrupts
handler. It is the machine check handler that establishes
the work and schedules the external interrupt, therefore
the machine check interrupt itself should be disabled
while reading out the corresponding variable:

local_mcck_disable();
mcck = *this_cpu_ptr(&cpu_mcck);
memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
local_mcck_enable();

However, local_mcck_disable() does not have effect when
__s390_handle_mcck() is called directly form the machine
check handler, since the machine check interrupt is still
disabled. Therefore, it is not the opening bracket to the
following local_mcck_enable() function.

Simplify the user process termination flow by scheduling
the external interrupt and killing the affected process
from the interrupt context.

Assume a kernel-generated signal is always delivered and
ignore a value returned by do_send_sig_info() funciton.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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s390/nmi: fix virtual-physical address confusion

When a machine check is received while in SIE, it is reinjected into the
guest in some cases. The respective code needs to access the sie_block,
whic

s390/nmi: fix virtual-physical address confusion

When a machine check is received while in SIE, it is reinjected into the
guest in some cases. The respective code needs to access the sie_block,
which is taken from the backed up R14.

Since reinjection only occurs while we are in SIE (i.e. between the
labels sie_entry and sie_leave in entry.S and thus if CIF_MCCK_GUEST is
set), the backed up R14 will always contain a physical address in
s390_backup_mcck_info.

This currently works, because virtual and physical addresses are
the same.

Add phys_to_virt() to resolve the virtual-physical confusion.

Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Link: https://lore.kernel.org/r/20230216121208.4390-2-nrb@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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s390/nmi: get rid of private slab cache

Get rid of private "nmi_save_areas" slab cache. The only reason this was
introduced years ago was that with some slab debugging options allocations
would only

s390/nmi: get rid of private slab cache

Get rid of private "nmi_save_areas" slab cache. The only reason this was
introduced years ago was that with some slab debugging options allocations
would only guarantee a minimum alignment of ARCH_KMALLOC_MINALIGN, which
was eight bytes back then. This is not sufficient for the extended machine
check save area.

However since commit 59bb47985c1d ("mm, sl[aou]b: guarantee natural
alignment for kmalloc(power-of-two)") kmalloc guarantees a power-of-two
alignment even with debugging options enabled.

Therefore the private slab cache can be removed.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

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s390/nmi: move storage error checking back to C, enter with DAT on

Checking for storage errors in machine check entry code was done in order
to handle also storage errors on kernel page tables. Howe

s390/nmi: move storage error checking back to C, enter with DAT on

Checking for storage errors in machine check entry code was done in order
to handle also storage errors on kernel page tables. However this is
extremely unlikely and some basic assumptions what works on machine check
entry are necessary anyway. In order to simplify machine check handling
delay checking for storage errors to C code.
With this also change the machine check new PSW to have DAT on, which
simplifies the entry code even further.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

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s390/nmi: print machine check interruption code before stopping system

In case a system will be stopped because of e.g. missing validity bits
print the machine check interruption code before the sys

s390/nmi: print machine check interruption code before stopping system

In case a system will be stopped because of e.g. missing validity bits
print the machine check interruption code before the system is stopped.

This is helpful, since up to now no message was printed in such a
case. Only a disabled wait PSW was loaded, which doesn't give a hint of
what went wrong.
Improve this by printing a message with debug information.

Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

show more ...

s390/nmi: rework register validation handling

If a machine check happens in kernel mode, and the machine check
interruption code indicates that e.g. vector register contents in the
machine check are

s390/nmi: rework register validation handling

If a machine check happens in kernel mode, and the machine check
interruption code indicates that e.g. vector register contents in the
machine check area are not valid, the logic is to kill current.

The idea behind this was that if within kernel context vector
registers are not used then it is sufficient to kill the current user
space process to avoid that it continues with potentially corrupt
register contents. This however does not necessarily work, since the
current code does not take into account that a machine check can also
happen when a kernel thread is running (= no user space context), and
in addition there is no way to distinguish between the "previous" and
"next" user process task, if the machine check happens when a task
switch happens.

Given that machine checks with invalid saved register contents in the
machine check save area are extremely rare, simplify the logic: if
register contents are invalid and the previous context was kernel
mode, stop the whole machine. If the previous context was user mode,
kill the corresponding task.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

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s390/nmi: use vector instruction macros instead of byte patterns

Use vector instruction macros instead of byte patterns to increase
readability. The generated code is nearly identical:

- 1e8: e7 0

s390/nmi: use vector instruction macros instead of byte patterns

Use vector instruction macros instead of byte patterns to increase
readability. The generated code is nearly identical:

- 1e8: e7 0f 10 00 00 36 vlm %v0,%v15,0(%r1)
- 1ee: e7 0f 11 00 0c 36 vlm %v16,%v31,256(%r1)
+ 1e8: e7 0f 10 00 30 36 vlm %v0,%v15,0(%r1),3
+ 1ee: e7 0f 11 00 3c 36 vlm %v16,%v31,256(%r1),3

By using the VLM macro the alignment hint is automatically specified
too. Even though from a performance perspective it doesn't matter at
all for the machine check code, this shows yet another benefit when
using the macros.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

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s390/boot: fix absolute zero lowcore corruption on boot

Crash dump always starts on CPU0. In case CPU0 is offline the
prefix page is not installed and the absolute zero lowcore is
used. However, str

s390/boot: fix absolute zero lowcore corruption on boot

Crash dump always starts on CPU0. In case CPU0 is offline the
prefix page is not installed and the absolute zero lowcore is
used. However, struct lowcore::mcesad is never assigned and
stays zero. That leads to __machine_kdump() -> save_vx_regs()
call silently stores vector registers to the absolute lowcore
at 0x11b0 offset.

Fixes: a62bc0739253 ("s390/kdump: add support for vector extension")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

show more ...

s390/nmi: use irqentry_nmi_enter()/irqentry_nmi_exit()

With generic entry in place switch the nmi handler to use
the generic entry helper functions.

Signed-off-by: Sven Schnelle <svens@linux.ibm.co

s390/nmi: use irqentry_nmi_enter()/irqentry_nmi_exit()

With generic entry in place switch the nmi handler to use
the generic entry helper functions.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

show more ...

s390/pai: add support for cryptography counters

PMU device driver perf_pai_crypto supports Processor Activity
Instrumentation (PAI), available with IBM z16:
- maps a full page to lowcore address 0x1

s390/pai: add support for cryptography counters

PMU device driver perf_pai_crypto supports Processor Activity
Instrumentation (PAI), available with IBM z16:
- maps a full page to lowcore address 0x1500.
- uses CR0 bit 13 to turn PAI crypto counting on and off.
- creates a sample with raw data on each context switch out when
at context switch some mapped counters have a value of nonzero.
This device driver only supports CPU wide context, no task context
is allowed.

Support for counting:
- one or more counters can be specified using
perf stat -e pai_crypto/xxx/
where xxx stands for the counter event name. Multiple invocation
of this command is possible. The counter names are listed in
/sys/devices/pai_crypto/events directory.
- one special counters can be specified using
perf stat -e pai_crypto/CRYPTO_ALL/
which returns the sum of all incremented crypto counters.
- one event pai_crypto/CRYPTO_ALL/ is reserved for sampling.
No multiple invocations are possible. The event collects data at
context switch out and saves them in the ring buffer.

Add qpaci assembly instruction to query supported memory mapped crypto
counters. It returns the number of counters (no holes allowed in that
range).

The PAI crypto counter events are system wide and can not be executed
in parallel. Therefore some restrictions documented in function
paicrypt_busy apply.
In particular event CRYPTO_ALL for sampling must run exclusive.
Only counting events can run in parallel.

PAI crypto counter events can not be created when a CPU hot plug
add is processed. This means a CPU hot plug add does not get
the necessary PAI event to record PAI cryptography counter increments
on the newly added CPU. CPU hot plug remove removes the event and
terminates the counting of PAI counters immediately.

Co-developed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Link: https://lore.kernel.org/r/20220504062351.2954280-3-tmricht@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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s390: remove invalid email address of Heiko Carstens

Remove my old invalid email address which can be found in a couple of
files. Instead of updating it, just remove my contact data completely
from

s390: remove invalid email address of Heiko Carstens

Remove my old invalid email address which can be found in a couple of
files. Instead of updating it, just remove my contact data completely
from source files.
We have git and other tools which allow to figure out who is responsible
for what with recent contact data.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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s390/nmi: handle vector validity failures for KVM guests

The machine check validity bit tells about the context. If a KVM guest
was running the bit tells about the guest validity and the host state

s390/nmi: handle vector validity failures for KVM guests

The machine check validity bit tells about the context. If a KVM guest
was running the bit tells about the guest validity and the host state is
not affected. As a guest can disable the guest validity this might
result in unwanted host errors on machine checks.

Cc: stable@vger.kernel.org
Fixes: c929500d7a5a ("s390/nmi: s390: New low level handling for machine check happening in guest")
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/nmi: handle guarded storage validity failures for KVM guests

machine check validity bits reflect the state of the machine check. If a
guest does not make use of guarded storage, the validity bi

s390/nmi: handle guarded storage validity failures for KVM guests

machine check validity bits reflect the state of the machine check. If a
guest does not make use of guarded storage, the validity bit might be
off. We can not use the host CR bit to decide if the validity bit must
be on. So ignore "invalid" guarded storage controls for KVM guests in
the host and rely on the machine check being forwarded to the guest. If
no other errors happen from a host perspective everything is fine and no
process must be killed and the host can continue to run.

Cc: stable@vger.kernel.org
Fixes: c929500d7a5a ("s390/nmi: s390: New low level handling for machine check happening in guest")
Reported-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Tested-by: Carsten Otte <cotte@de.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

show more ...

s390/nmi: disable interrupts on extended save area update

Updating of the pointer to machine check extended save area
on the IPL CPU needs the lowcore protection to be disabled.
Disable interrupts w

s390/nmi: disable interrupts on extended save area update

Updating of the pointer to machine check extended save area
on the IPL CPU needs the lowcore protection to be disabled.
Disable interrupts while the protection is off to avoid
unnoticed writes to the lowcore.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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exit: Add and use make_task_dead.

There are two big uses of do_exit. The first is it's design use to be
the guts of the exit(2) system call. The second use is to terminate
a task after something c

exit: Add and use make_task_dead.

There are two big uses of do_exit. The first is it's design use to be
the guts of the exit(2) system call. The second use is to terminate
a task after something catastrophic has happened like a NULL pointer
in kernel code.

Add a function make_task_dead that is initialy exactly the same as
do_exit to cover the cases where do_exit is called to handle
catastrophic failure. In time this can probably be reduced to just a
light wrapper around do_task_dead. For now keep it exactly the same so
that there will be no behavioral differences introducing this new
concept.

Replace all of the uses of do_exit that use it for catastraphic
task cleanup with make_task_dead to make it clear what the code
is doing.

As part of this rename rewind_stack_do_exit
rewind_stack_and_make_dead.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

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s390/nmi: add missing __pa/__va address conversion of extended save area

Add missing __pa/__va address conversion of machine check extended
save area designation, which is an absolute address.

Note

s390/nmi: add missing __pa/__va address conversion of extended save area

Add missing __pa/__va address conversion of machine check extended
save area designation, which is an absolute address.

Note: this currently doesn't fix a real bug, since virtual addresses
are indentical to physical ones.

Reported-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Tested-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

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s390/boot: fix absolute zero lowcore corruption on boot

[ Upstream commit 12dd19c159659ec9050f45dc8a2ff3c3917f4be3 ]

Crash dump always starts on CPU0. In case CPU0 is offline the
prefix page is not

s390/boot: fix absolute zero lowcore corruption on boot

[ Upstream commit 12dd19c159659ec9050f45dc8a2ff3c3917f4be3 ]

Crash dump always starts on CPU0. In case CPU0 is offline the
prefix page is not installed and the absolute zero lowcore is
used. However, struct lowcore::mcesad is never assigned and
stays zero. That leads to __machine_kdump() -> save_vx_regs()
call silently stores vector registers to the absolute lowcore
at 0x11b0 offset.

Fixes: a62bc0739253 ("s390/kdump: add support for vector extension")
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

show more ...

s390/nmi: handle vector validity failures for KVM guests

commit f094a39c6ba168f2df1edfd1731cca377af5f442 upstream.

The machine check validity bit tells about the context. If a KVM guest
was running

s390/nmi: handle vector validity failures for KVM guests

commit f094a39c6ba168f2df1edfd1731cca377af5f442 upstream.

The machine check validity bit tells about the context. If a KVM guest
was running the bit tells about the guest validity and the host state is
not affected. As a guest can disable the guest validity this might
result in unwanted host errors on machine checks.

Cc: stable@vger.kernel.org
Fixes: c929500d7a5a ("s390/nmi: s390: New low level handling for machine check happening in guest")
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

show more ...

s390/nmi: handle guarded storage validity failures for KVM guests

commit 1ea1d6a847d2b1d17fefd9196664b95f052a0775 upstream.

machine check validity bits reflect the state of the machine check. If a

s390/nmi: handle guarded storage validity failures for KVM guests

commit 1ea1d6a847d2b1d17fefd9196664b95f052a0775 upstream.

machine check validity bits reflect the state of the machine check. If a
guest does not make use of guarded storage, the validity bit might be
off. We can not use the host CR bit to decide if the validity bit must
be on. So ignore "invalid" guarded storage controls for KVM guests in
the host and rely on the machine check being forwarded to the guest. If
no other errors happen from a host perspective everything is fine and no
process must be killed and the host can continue to run.

Cc: stable@vger.kernel.org
Fixes: c929500d7a5a ("s390/nmi: s390: New low level handling for machine check happening in guest")
Reported-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Tested-by: Carsten Otte <cotte@de.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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s390/mcck: move register validation to C code

This update partially reverts commit 3037a52f9846 ("s390/nmi:
do register validation as early as possible").

Storage error checks and control registers

s390/mcck: move register validation to C code

This update partially reverts commit 3037a52f9846 ("s390/nmi:
do register validation as early as possible").

Storage error checks and control registers validation are left
in the assembler code, since correct ASCEs and page tables are
required to enable DAT - which is done before the C handler is
entered.

System damage, kernel instruction address and PSW MWP checks
are left in the assembler code as well, since there is no way
to proceed if one of these checks is failed.

The getcpu vdso syscall reads CPU number from the programmable
field of the TOD clock. Disregard the TOD programmable register
validity bit and load the CPU number into the TOD programmable
field unconditionally.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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s390/mcck: move storage error checks to assembler

The current storage errors tackling is wrong - the DAT is
enabled in assembler code before the actual storage checks
in C half are executed. In case

s390/mcck: move storage error checks to assembler

The current storage errors tackling is wrong - the DAT is
enabled in assembler code before the actual storage checks
in C half are executed. In case the page tables themselves
are damaged such approach is not going to work.

With this update unrecoverable storage errors are not
passed to C code for handling, but rather the machine
is stopped right away. The only exception to this flow
is when a machine check occurred in KVM guest - in this
case the errors are reinjected by the handler.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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s390/mcck: always enter C handler with DAT enabled

The machine check handler must be entered with DAT disabled
in case control registers are corrupted or a storage error
happened and we can not tell

s390/mcck: always enter C handler with DAT enabled

The machine check handler must be entered with DAT disabled
in case control registers are corrupted or a storage error
happened and we can not tell if such error corresponds to a
page table.

Both of described conditions end up in stopping all CPUs and
entering the disabled wait in C half of the handler. However,
the storage errors are still checked after the DAT is enabled
and C code is entered. In case a page table is damaged such
flow is not expected to work.

This update paves the way for moving the storage error checks
from C to assembler half. All fatal errors that can only be
handled with DAT disabled are handled in assembler half also.
As result, the C half is only entered if the DAT is secured.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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s390: convert to generic entry

This patch converts s390 to use the generic entry infrastructure from
kernel/entry/*.

There are a few special things on s390:

- PIF_PER_TRAP is moved to TIF_PER_TRAP

s390: convert to generic entry

This patch converts s390 to use the generic entry infrastructure from
kernel/entry/*.

There are a few special things on s390:

- PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't
know about our PIF flags in exit_to_user_mode_loop().

- The old code had several ways to restart syscalls:

a) PIF_SYSCALL_RESTART, which was only set during execve to force a
restart after upgrading a process (usually qemu-kvm) to pgste page
table extensions.

b) PIF_SYSCALL, which is set by do_signal() to indicate that the
current syscall should be restarted. This is changed so that
do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use
PIF_SYSCALL doesn't work with the generic code, and changing it
to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART
more unique.

- On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by
executing a svc instruction on the process stack which causes a fault.
While handling that fault the fault code sets PIF_SYSCALL to hand over
processing to the syscall code on exit to usermode.

The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets
a return value for a syscall. The s390x ptrace ABI uses r2 both for the
syscall number and return value, so ptrace cannot set the syscall number +
return value at the same time. The flag makes handling that a bit easier.
do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET
is set.

CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY.
CR1/7/13 will be checked both on kernel entry and exit to contain the
correct asces.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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s390: remove critical section cleanup from entry.S

The current code is rather complex and caused a lot of subtle
and hard to debug bugs in the past. Simplify the code by calling
the system_call hand

s390: remove critical section cleanup from entry.S

The current code is rather complex and caused a lot of subtle
and hard to debug bugs in the past. Simplify the code by calling
the system_call handler with interrupts disabled, save
machine state, and re-enable them later.

This requires significant changes to the machine check handling code
as well. When the machine check interrupt arrived while being in kernel
mode the new code will signal pending machine checks with a SIGP external
call. When userspace was interrupted, the handler will switch to the
kernel stack and directly execute s390_handle_mcck().

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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s390: simplify disabled_wait

The disabled_wait() function uses its argument as the PSW address when
it stops the CPU with a wait PSW that is disabled for interrupts.
The different callers sometimes

s390: simplify disabled_wait

The disabled_wait() function uses its argument as the PSW address when
it stops the CPU with a wait PSW that is disabled for interrupts.
The different callers sometimes use a specific number like 0xdeadbeef
to indicate a specific failure, the early boot code uses 0 and some
other calls sites use __builtin_return_address(0).

At the time a dump is created the current PSW and the registers of a
CPU are written to lowcore to make them avaiable to the dump analysis
tool. For a CPU stopped with disabled_wait the PSW and the registers
do not really make sense together, the PSW address does not point to
the function the registers belong to.

Simplify disabled_wait() by using _THIS_IP_ for the PSW address and
drop the argument to the function.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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