s390/nmi: do register validation as early as possible

The validation of the CPU registers in the machine check handler is
currently split into two parts. The first part is done at the st

s390/nmi: do register validation as early as possible

The validation of the CPU registers in the machine check handler is
currently split into two parts. The first part is done at the start
of the low level mcck_int_handler function, this includes the CPU
timer register and the general purpose registers.
The second part is done a bit later in s390_do_machine_check for all
the other registers, including the control registers, floating pointer
control, vector or floating pointer registers, the access registers,
the guarded storage registers, the TOD programmable registers and the
clock comparator.

This is working fine to far but in theory a future extensions could
cause the C code to use registers that are not validated yet. A better
approach is to validate all CPU registers in "safe" assembler code
before any C function is called.

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

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s390/nmi: allocation of the extended save area

The machine check extended save area is needed to store the vector
registers and the guarded storage control block when a CPU is
interr

s390/nmi: allocation of the extended save area

The machine check extended save area is needed to store the vector
registers and the guarded storage control block when a CPU is
interrupted by a machine check.

Move the slab cache allocation of the full save area to nmi.c,
for early boot use a static __initdata block.

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

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s390/ctl_reg: use decoding unions in update_cr_regs

Add a decoding union for the bits in control registers 2 and use
'union ctlreg0' and 'union ctlreg2' in update_cr_regs to improve

s390/ctl_reg: use decoding unions in update_cr_regs

Add a decoding union for the bits in control registers 2 and use
'union ctlreg0' and 'union ctlreg2' in update_cr_regs to improve
readability.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: use smp_emergency_stop instead of smp_send_stop

The smp_send_stop() function can be called from s390_handle_damage
while DAT is off. This happens if a machine check indicates t

s390/nmi: use smp_emergency_stop instead of smp_send_stop

The smp_send_stop() function can be called from s390_handle_damage
while DAT is off. This happens if a machine check indicates that
kernel gprs or control registers can not be restored. The function
smp_send_stop reenables DAT via __load_psw_mask. That should work
for the case of lost kernel gprs and the system will do the expected
stop of all CPUs. But if control registers are lost, in particular
CR13 with the home space ASCE, interesting secondary crashes may
occur.

Make smp_emergency_stop callable from nmi.c and remove the cpumask
argument. Replace the smp_send_stop call with smp_emergency_stop in
the s390_handle_damage function.

In addition add notrace and NOKPROBE_SYMBOL annotations for all
functions required for the emergency shutdown.

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

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KVM: s390: Backup the guest's machine check info

When a machine check happens in the guest, related mcck info (mcic,
external damage code, ...) is stored in the vcpu's lowcore on the hos

KVM: s390: Backup the guest's machine check info

When a machine check happens in the guest, related mcck info (mcic,
external damage code, ...) is stored in the vcpu's lowcore on the host.
Then the machine check handler's low-level part is executed, followed
by the high-level part.

If the high-level part's execution is interrupted by a new machine check
happening on the same vcpu on the host, the mcck info in the lowcore is
overwritten with the new machine check's data.

If the high-level part's execution is scheduled to a different cpu,
the mcck info in the lowcore is uncertain.

Therefore, for both cases, the further reinjection to the guest will use
the wrong data.
Let's backup the mcck info in the lowcore to the sie page
for further reinjection, so that the right data will be used.

Add new member into struct sie_page to store related machine check's
info of mcic, failing storage address and external damage code.

Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

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s390/nmi: s390: New low level handling for machine check happening in guest

Add the logic to check if the machine check happens when the guest is
running. If yes, set the exit reason -EI

s390/nmi: s390: New low level handling for machine check happening in guest

Add the logic to check if the machine check happens when the guest is
running. If yes, set the exit reason -EINTR in the machine check's
interrupt handler. Refactor s390_do_machine_check to avoid panicing
the host for some kinds of machine checks which happen
when guest is running.
Reinject the instruction processing damage's machine checks including
Delayed Access Exception instead of damaging the host if it happens
in the guest because it could be caused by improper update on TLB entry
or other software case and impacts the guest only.

Signed-off-by: QingFeng Hao <haoqf@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

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s390: add a system call for guarded storage

This adds a new system call to enable the use of guarded storage for
user space processes. The system call takes two arguments, a command

s390: add a system call for guarded storage

This adds a new system call to enable the use of guarded storage for
user space processes. The system call takes two arguments, a command
and pointer to a guarded storage control block:

s390_guarded_storage(int command, struct gs_cb *gs_cb);

The second argument is relevant only for the GS_SET_BC_CB command.

The commands in detail:

0 - GS_ENABLE
Enable the guarded storage facility for the current task. The
initial content of the guarded storage control block will be
all zeros. After the enablement the user space code can use
load-guarded-storage-controls instruction (LGSC) to load an
arbitrary control block. While a task is enabled the kernel
will save and restore the current content of the guarded
storage registers on context switch.
1 - GS_DISABLE
Disables the use of the guarded storage facility for the current
task. The kernel will cease to save and restore the content of
the guarded storage registers, the task specific content of
these registers is lost.
2 - GS_SET_BC_CB
Set a broadcast guarded storage control block. This is called
per thread and stores a specific guarded storage control block
in the task struct of the current task. This control block will
be used for the broadcast event GS_BROADCAST.
3 - GS_CLEAR_BC_CB
Clears the broadcast guarded storage control block. The guarded-
storage control block is removed from the task struct that was
established by GS_SET_BC_CB.
4 - GS_BROADCAST
Sends a broadcast to all thread siblings of the current task.
Every sibling that has established a broadcast guarded storage
control block will load this control block and will be enabled
for guarded storage. The broadcast guarded storage control block
is used up, a second broadcast without a refresh of the stored
control block with GS_SET_BC_CB will not have any effect.

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

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sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h>

We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be

sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h>

We are going to split <linux/sched/signal.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.

Create a trivial placeholder <linux/sched/signal.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.

Include the new header in the files that are going to need it.

Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

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s390/nmi: purge tlbs after control register validation

Play safe and purge all tlbs after the control registers that contain
the primary, secondary and home space asces have been validat

s390/nmi: purge tlbs after control register validation

Play safe and purge all tlbs after the control registers that contain
the primary, secondary and home space asces have been validated.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: fix order of register validation

When validating register contents first validate control registers
since these control the availability of features later being
validated.

s390/nmi: fix order of register validation

When validating register contents first validate control registers
since these control the availability of features later being
validated.
For example the control register 0 should be validated first, before
the additional floating point (AFP) registers are validated, since
control register 0 contains the AFP-register control bit.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390: kernel: Audit and remove any unnecessary uses of module.h

Historically a lot of these existed because we did not have
a distinction between what was modular code and what was provi

s390: kernel: Audit and remove any unnecessary uses of module.h

Historically a lot of these existed because we did not have
a distinction between what was modular code and what was providing
support to modules via EXPORT_SYMBOL and friends. That changed
when we forked out support for the latter into the export.h file.

This means we should be able to reduce the usage of module.h
in code that is obj-y Makefile or bool Kconfig. The advantage
in doing so is that module.h itself sources about 15 other headers;
adding significantly to what we feed cpp, and it can obscure what
headers we are effectively using.

Since module.h was the source for init.h (for __init) and for
export.h (for EXPORT_SYMBOL) we consider each change instance
for the presence of either and replace as needed. Build testing
revealed some implicit header usage that was fixed up accordingly.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: fix inline assembly constraints

Add missing memory clobbers / barriers or use the Q constraint where
possible to tell the compiler that the inline assemblies actually
acces

s390/nmi: fix inline assembly constraints

Add missing memory clobbers / barriers or use the Q constraint where
possible to tell the compiler that the inline assemblies actually
access memory and not only pointers to memory.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: improve revalidation of fpu / vector registers

The machine check handler will do one of two things if the floating-point
control, a floating point register or a vector register

s390/nmi: improve revalidation of fpu / vector registers

The machine check handler will do one of two things if the floating-point
control, a floating point register or a vector register can not be
revalidated:
1) if the PSW indicates user mode the process is terminated
2) if the PSW indicates kernel mode the system is stopped

To unconditionally stop the system for 2) is incorrect.

There are three possible outcomes if the floating-point control, a
floating point register or a vector registers can not be revalidated:
1) The kernel is inside a kernel_fpu_begin/kernel_fpu_end block and
needs the register. The system is stopped.
2) No active kernel_fpu_begin/kernel_fpu_end block and the CIF_CPU bit
is not set. The user space process needs the register and is killed.
3) No active kernel_fpu_begin/kernel_fpu_end block and the CIF_FPU bit
is set. Neither the kernel nor the user space process needs the
lost register. Just revalidate it and continue.

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

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s390/time: remove ETR support

The External-Time-Reference (ETR) clock synchronization interface has
been superseded by Server-Time-Protocol (STP). Remove the outdated
ETR interface.

s390/time: remove ETR support

The External-Time-Reference (ETR) clock synchronization interface has
been superseded by Server-Time-Protocol (STP). Remove the outdated
ETR interface.

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

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s390/nmi: reduce size of percpu variable

Change the flag fields within struct mcck_struct to simple bit fields
to reduce the size of the structure which is used as percpu variable.

s390/nmi: reduce size of percpu variable

Change the flag fields within struct mcck_struct to simple bit fields
to reduce the size of the structure which is used as percpu variable.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: fix terminology

According to the architecture registers are validated and not
revalidated. So change comments and functions names to match.

Signed-off-by: Heiko Carste

s390/nmi: fix terminology

According to the architecture registers are validated and not
revalidated. So change comments and functions names to match.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: remove casts

Remove all the casts to and from the machine check interruption code.
This patch changes struct mci to a union, which contains an anonymous
structure with the

s390/nmi: remove casts

Remove all the casts to and from the machine check interruption code.
This patch changes struct mci to a union, which contains an anonymous
structure with the already known bits and in addition an unsigned
long field, which contains the raw machine check interruption code.

This allows to simply assign and decoce the interruption code value
without the need for all those casts we had all the time.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: remove pointless error strings

s390_handle_damage() has character string parameter which was used as
a pointer to verbose error message. The hope was (a lot of years ago)
w

s390/nmi: remove pointless error strings

s390_handle_damage() has character string parameter which was used as
a pointer to verbose error message. The hope was (a lot of years ago)
when analyzing dumps that register R2 would still contain the pointer
and therefore it would be rather easy to tell what went wrong.

However gcc optimizes the strings away since a long time. And even if
it wouldn't it is necessary to have a close look at the machine check
interruption code to tell what's wrong.

So remove the pointless error strings.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/fpu: split fpu-internal.h into fpu internals, api, and type headers

Split the API and FPU type definitions into separate header files
similar to "x86/fpu: Rename fpu-internal.h to f

s390/fpu: split fpu-internal.h into fpu internals, api, and type headers

Split the API and FPU type definitions into separate header files
similar to "x86/fpu: Rename fpu-internal.h to fpu/internal.h" (78f7f1e54b).

The new header files and their meaning are:

asm/fpu/types.h:
FPU related data types, needed for 'struct thread_struct' and
'struct task_struct'.

asm/fpu/api.h:
FPU related 'public' functions for other subsystems and device
drivers.

asm/fpu/internal.h:
FPU internal functions mainly used to convert
FPU register contents in signal handling.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/etr,stp: fix possible deadlock on machine check

The first level machine check handler for etr and stp machine checks may
call queue_work() while in nmi context. This may deadlock e.

s390/etr,stp: fix possible deadlock on machine check

The first level machine check handler for etr and stp machine checks may
call queue_work() while in nmi context. This may deadlock e.g. if the
machine check happened when the interrupted context did hold a lock, that
also will be acquired by queue_work().
Therefore split etr and stp machine check handling into first and second
level handling. The second level handling will then issue the queue_work()
call in process context which avoids the potential deadlock.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: initialize control register 0 earlier

Change machine_check_init() to an early_initcall(). This makes sure it will
be called before all other cpus are online and therfore saves

s390/nmi: initialize control register 0 earlier

Change machine_check_init() to an early_initcall(). This makes sure it will
be called before all other cpus are online and therfore saves us a lot of
pointless smp_call_function() calls.
The control register settings will be forwarded to the other cpus when they
will be brought online.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/kernel: lazy restore fpu registers

Improve the save and restore behavior of FPU register contents to use the
vector extension within the kernel.

The kernel does not use flo

s390/kernel: lazy restore fpu registers

Improve the save and restore behavior of FPU register contents to use the
vector extension within the kernel.

The kernel does not use floating-point or vector registers and, therefore,
saving and restoring the FPU register contents are performed for handling
signals or switching processes only. To prepare for using vector
instructions and vector registers within the kernel, enhance the save
behavior and implement a lazy restore at return to user space from a
system call or interrupt.

To implement the lazy restore, the save_fpu_regs() sets a CPU information
flag, CIF_FPU, to indicate that the FPU registers must be restored.
Saving and setting CIF_FPU is performed in an atomic fashion to be
interrupt-safe. When the kernel wants to use the vector extension or
wants to change the FPU register state for a task during signal handling,
the save_fpu_regs() must be called first. The CIF_FPU flag is also set at
process switch. At return to user space, the FPU state is restored. In
particular, the FPU state includes the floating-point or vector register
contents, as well as, vector-enablement and floating-point control. The
FPU state restore and clearing CIF_FPU is also performed in an atomic
fashion.

For KVM, the restore of the FPU register state is performed when restoring
the general-purpose guest registers before the SIE instructions is started.
Because the path towards the SIE instruction is interruptible, the CIF_FPU
flag must be checked again right before going into SIE. If set, the guest
registers must be reloaded again by re-entering the outer SIE loop. This
is the same behavior as if the SIE critical section is interrupted.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/kernel: introduce fpu-internal.h with fpu helper functions

Introduce a new structure to manage FP and VX registers. Refactor the
save and restore of floating point and vector regist

s390/kernel: introduce fpu-internal.h with fpu helper functions

Introduce a new structure to manage FP and VX registers. Refactor the
save and restore of floating point and vector registers with a set
of helper functions in fpu-internal.h.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390/nmi: fix vector register corruption

If a machine check happens, the machine has the vector facility installed
and the extended save area exists, the cpu will save vector register

s390/nmi: fix vector register corruption

If a machine check happens, the machine has the vector facility installed
and the extended save area exists, the cpu will save vector register
contents into the extended save area. This is regardless of control
register 0 contents, which enables and disables the vector facility during
runtime.

On each machine check we should validate the vector registers. The current
code however tries to validate the registers only if the running task is
using vector registers in user space.

However even the current code is broken and causes vector register
corruption on machine checks, if user space uses them:
the prefix area contains a pointer (absolute address) to the machine check
extended save area. In order to save some space the save area was put into
an unused area of the second prefix page.
When validating vector register contents the code uses the absolute address
of the extended save area, which is wrong. Due to prefixing the vector
instructions will then access contents using absolute addresses instead
of real addresses, where the machine stored the contents.

If the above would work there is still the problem that register validition
would only happen if user space uses vector registers. If kernel space uses
them also, this may also lead to vector register content corruption:
if the kernel makes use of vector instructions, but the current running
user space context does not, the machine check handler will validate
floating point registers instead of vector registers.
Given the fact that writing to a floating point register may change the
upper halve of the corresponding vector register, we also experience vector
register corruption in this case.

Fix all of these issues, and always validate vector registers on each
machine check, if the machine has the vector facility installed and the
extended save area is defined.

Cc: <stable@vger.kernel.org> # 4.1+
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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s390: remove 31 bit support

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

s390: remove 31 bit support

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

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