s390/fpu: make kernel fpu context preemptible

Make the kernel fpu context preemptible. Add another fpu structure to the
thread_struct, and use it to save and restore the kernel fpu context if its
task uses fpu registers when it is preempted.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

s390: delete the unused store_prefix() function

Its last usage was deleted in commit 4df29d2b9024 ("s390/smp: rework
absolute lowcore access").

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

s390/ctlreg: add struct ctlreg

Add struct ctlreg to enforce strict type checking / usage for control
register functions.

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

s390/ctlreg: use local_ctl_load() and local_ctl_store() where possible

Convert all single control register usages of __local_ctl_load() and
__local_ctl_store() to local_ctl_load() and local_ctl_store().

This also requires to change the type of some struct lowcore members
from __u64 to unsigned long.

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

s390/entry: remove mcck clock

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

s390/pai: Add support for PAI Extension 1 NNPA counters

PMU device driver perf_paiext supports Processor Activity
Instrumentation Extension (PAIE1), available with IBM z16:
- maps a 512 byte block to lowcore address 0x1508 called PAIE1 control
block.
- maps a 1024 byte block at PAIE1 control block entry with index 2.
- uses control register bit 14 to enable PAIE1 control block lookup.
- turn PAIE1 nnpa counting on and off by setting bit 63 in
PAIE1 control block entry with index 2.
- 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_ext/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_ext/events directory.
- one special counters can be specified using
perf stat -e pai_ext/NNPA_ALL/
which returns the sum of all incremented nnpa counters.
- multiple counting events can run in parallel.

Support for Sampling:
- one event pai_ext/NNPA_ALL/ is reserved for sampling.
The event collects data at context switch out and saves them in
the ring buffer.
- no multiple invocations are possible.

The PAIE1 nnpa counter events are system wide. No task context is
supported. Therefore some restrictions documented in function
paiext_busy() apply.

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

PAIE1 nnpa 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 PAIE1 event to record PAIE1 nnpa counter increments
on the newly added CPU. CPU hot plug remove removes the event and
terminates the counting of PAIE1 counters immediately.

Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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>

s390: raise minimum supported machine generation to z10

Machine generations up to z9 (released in May 2006) have been officially
out of service for several years now (z9 end of service - January 31, 2019).
No distributions build kernels supporting those old machine generations
anymore, except Debian, which seems to pick the oldest supported
generation. The team supporting Debian on s390 has been notified about
the change.

Raising minimum supported machine generation to z10 helps to reduce
maintenance cost and effectively remove code, which is not getting
enough testing coverage due to lack of older hardware and distributions
support. Besides that this unblocks some optimization opportunities and
allows to use wider instruction set in asm files for future features
implementation. Due to this change spectre mitigation and usercopy
implementations could be drastically simplified and many newer instructions
could be converted from ".insn" encoding to instruction names.

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

s390/traps: get rid of magic cast for per code

Add a proper union in lowcore to reflect architecture and get rid of a
"magic" cast in order to read the full per code.

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

s390/traps: get rid of magic cast for program interruption code

Add a proper union in lowcore to reflect architecture and get rid of a
"magic" cast in order to read the full program interruption code.

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

s390: add support for BEAR enhancement facility

The Breaking-Event-Address-Register (BEAR) stores the address of the
last breaking event instruction. Breaking events are usually instructions
that change the program flow - for example branches, and instructions
that modify the address in the PSW like lpswe. This is useful for debugging
wild branches, because one could easily figure out where the wild branch
was originating from.

What is problematic is that lpswe is considered a breaking event, and
therefore overwrites BEAR on kernel exit. The BEAR enhancement facility
adds new instructions that allow to save/restore BEAR and also an lpswey
instruction that doesn't cause a breaking event. So we can save BEAR on
kernel entry and restore it on exit to user space.

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

s390: rename last_break to pgm_last_break

With the upcoming BEAR enhancements last_break isn't really
unique, so rename it to pgm_last_break. This way it should
be more obvious that this is the last_break value that is
written by the hardware when a program check occurs.

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

s390/smp: enable DAT before CPU restart callback is called

The restart interrupt is triggered whenever a secondary CPU is
brought online, a remote function call dispatched from another
CPU or a manual PSW restart is initiated and causes the system
to kdump. The handling routine is always called with DAT turned
off. It then initializes the stack frame and invokes a callback.

The existing callbacks handle DAT as follows:

* __do_restart() and __machine_kexec() turn in on upon entry;
* __ipl_run(), __reipl_run() and __dump_run() do not turn it
right away, but all of them call diag308() - which turns DAT
on, but only if kasan is enabled;

In addition to the described complexity all callbacks (and the
functions they call) should avoid kasan instrumentation while
DAT is off.

This update enables DAT in the assembler restart handler and
relieves any callbacks (which are mostly C functions) from
dealing with DAT altogether.

There are four types of CPU restart that initialize control
registers in different ways:

1. Start of secondary CPU on boot - control registers are
inherited from the IPL CPU;
2. Restart of online CPU - control registers of the CPU being
restarted are kept;
3. Hotplug of offline CPU - control registers are inherited
from the starting CPU;
4. Start of offline CPU triggered by manual PSW restart -
the control registers are read from the absolute lowcore
and contain the boot time IPL CPU values updated with all
follow-up calls of smp_ctl_set_bit() and smp_ctl_clear_bit()
routines;

In first three cases contents of the control registers is the
most recent. In the latter case control registers are good
enough to facilitate successful completion of kdump operation.

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>

s390/lowcore: remove superfluous __packed annotations

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

s390: use struct tpi_info in lowcore.h

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

s390/traps: add struct to access transactional diagnostic block

gcc-11 warns:

arch/s390/kernel/traps.c: In function __do_pgm_check:
arch/s390/kernel/traps.c:319:17: warning: memcpy reading 256 bytes from a region of size 0 [-Wstringop-overread]
319 | memcpy(&current->thread.trap_tdb, &S390_lowcore.pgm_tdb, 256);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by adding a struct pgm_tdb to struct lowcore and copy that.

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

s390/irq: add union/struct to access external interrupt parameters

gcc-11 warns:

arch/s390/kernel/irq.c: In function do_ext_irq:
arch/s390/kernel/irq.c:175:9: warning: memcpy reading 4 bytes from a region of size 0 [-Wstringop-overread]
175 | memcpy(&regs->int_code, &S390_lowcore.ext_cpu_addr, 4);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by adding a struct for int_code to struct lowcore.

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

s390/facilities: move stfl information from lowcore to global data

With gcc-11, there are a lot of warnings because the facility functions
are accessing lowcore through a null pointer. Fix this by moving the
facility arrays away from lowcore.

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

s390/entry: use assignment to read intcode / asm to copy gprs

arch/s390/kernel/syscall.c: In function __do_syscall:
arch/s390/kernel/syscall.c:147:9: warning: memcpy reading 64 bytes from a region of size 0 [-Wstringop-overread]
147 | memcpy(&regs->gprs[8], S390_lowcore.save_area_sync, 8 * sizeof(unsigned long));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
arch/s390/kernel/syscall.c:148:9: warning: memcpy reading 4 bytes from a region of size 0 [-Wstringop-overread]
148 | memcpy(&regs->int_code, &S390_lowcore.svc_ilc, sizeof(regs->int_code));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix this by moving the gprs restore from C to assembly, and use a assignment
for int_code instead of memcpy.

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

s390: add stack for machine check handler

The previous code used the normal kernel stack for machine checks.
This is problematic when a machine check interrupts a system call
or interrupt handler right at the beginning where registers are set up.

Assume system_call is interrupted at the first instruction and a machine
check is triggered. The machine check handler is called, checks the PSW
to see whether it is coming from user space, notices that it is already
in kernel mode but %r15 still contains the user space stack. This would
lead to a kernel crash.

There are basically two ways of fixing that: Either using the 'critical
cleanup' approach which compares the address in the PSW to see whether
it is already at a point where the stack has been set up, or use an extra
stack for the machine check handler.

For simplicity, we will go with the second approach and allocate an extra
stack. This adds some memory overhead for large systems, but usually large
system have plenty of memory so this isn't really a concern. But it keeps
the mchk stack setup simple and less error prone.

Fixes: 0b0ed657fe00 ("s390: remove critical section cleanup from entry.S")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Cc: <stable@kernel.org> # v5.8+
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

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>

s390/mm: remove set_fs / rework address space handling

Remove set_fs support from s390. With doing this rework address space
handling and simplify it. As a result address spaces are now setup
like this:

CPU running in | %cr1 ASCE | %cr7 ASCE | %cr13 ASCE
----------------------------|-----------|-----------|-----------
user space | user | user | kernel
kernel, normal execution | kernel | user | kernel
kernel, kvm guest execution | gmap | user | kernel

To achieve this the getcpu vdso syscall is removed in order to avoid
secondary address mode and a separate vdso address space in for user
space. The getcpu vdso syscall will be implemented differently with a
subsequent patch.

The kernel accesses user space always via secondary address space.
This happens in different ways:
- with mvcos in home space mode and directly read/write to secondary
address space
- with mvcs/mvcp in primary space mode and copy from primary space to
secondary space or vice versa
- with e.g. cs in secondary space mode and access secondary space

Switching translation modes happens with sacf before and after
instructions which access user space, like before.

Lazy handling of control register reloading is removed in the hope to
make everything simpler, but at the cost of making kernel entry and
exit a bit slower. That is: on kernel entry the primary asce is always
changed to contain the kernel asce, and on kernel exit the primary
asce is changed again so it contains the user asce.

In kernel mode there is only one exception to the primary asce: when
kvm guests are executed the primary asce contains the gmap asce (which
describes the guest address space). The primary asce is reset to
kernel asce whenever kvm guest execution is interrupted, so that this
doesn't has to be taken into account for any user space accesses.

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

s390: prevent leaking kernel address in BEAR

When userspace executes a syscall or gets interrupted,
BEAR contains a kernel address when returning to userspace.
This make it pretty easy to figure out where the kernel is
mapped even with KASLR enabled. To fix this, add lpswe to
lowcore and always execute it there, so userspace sees only
the lowcore address of lpswe. For this we have to extend
both critical_cleanup and the SWITCH_ASYNC macro to also check
for lpswe addresses in lowcore.

Fixes: b2d24b97b2a9 ("s390/kernel: add support for kernel address space layout randomization (KASLR)")
Cc: <stable@vger.kernel.org> # v5.2+
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

s390: fix clang -Wpointer-sign warnigns in boot code

The arch/s390/boot directory is built with its own set of compiler
options that does not include -Wno-pointer-sign like the rest of
the kernel does, this causes a lot of harmless but correct warnings
when building with clang.

For the atomics, we can add type casts to avoid the warnings, for
everything else the easiest way is to slightly adapt the types
to be more consistent.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/vtime: steal time exponential moving average

To be able to judge the current overcommitment ratio for a CPU add
a lowcore field with the exponential moving average of the steal time.
The average is updated every tick.

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

s390: add support for virtually mapped kernel stacks

With virtually mapped kernel stacks the kernel stack overflow detection
is now fault based, every stack has a guard page in the vmalloc space.
The panic_stack is renamed to nodat_stack and is used for all function
that need to run without DAT, e.g. memcpy_real or do_start_kdump.

The main effect is a reduction in the kernel image size as with vmap
stacks the old style overflow checking that adds two instructions per
function is not needed anymore. Result from bloat-o-meter:

add/remove: 20/1 grow/shrink: 13/26854 up/down: 2198/-216240 (-214042)

In regard to performance the micro-benchmark for fork has a hit of a
few microseconds, allocating 4 pages in vmalloc space is more expensive
compare to an order-2 page allocation. But with real workload I could
not find a noticeable difference.

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

s390: align struct lowcore to double page size

Aligning struct lowcore to double page size allows to get rid of this
gcc warning:

In file included from ./arch/s390/include/asm/setup.h:56,
from ./arch/s390/include/asm/page.h:36,
from ./arch/s390/include/asm/user.h:11,
from ./include/linux/user.h:1,
from ./include/linux/elfcore.h:5,
from ./include/linux/crash_core.h:6,
from ./include/linux/kexec.h:18,
from arch/s390/purgatory/purgatory.c:10:
./arch/s390/include/asm/lowcore.h:189:1: warning: alignment 1 of 'struct
lowcore' is less than 8 [-Wpacked-not-aligned]
} __packed;

Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390: introduce execute-trampolines for branches

Add CONFIG_EXPOLINE to enable the use of the new -mindirect-branch= and
-mfunction_return= compiler options to create a kernel fortified against
the specte v2 attack.

With CONFIG_EXPOLINE=y all indirect branches will be issued with an
execute type instruction. For z10 or newer the EXRL instruction will
be used, for older machines the EX instruction. The typical indirect
call

basr %r14,%r1

is replaced with a PC relative call to a new thunk

brasl %r14,__s390x_indirect_jump_r1

The thunk contains the EXRL/EX instruction to the indirect branch

__s390x_indirect_jump_r1:
exrl 0,0f
j .
0: br %r1

The detour via the execute type instruction has a performance impact.
To get rid of the detour the new kernel parameter "nospectre_v2" and
"spectre_v2=[on,off,auto]" can be used. If the parameter is specified
the kernel and module code will be patched at runtime.

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

s390/alternative: use a copy of the facility bit mask

To be able to switch off specific CPU alternatives with kernel parameters
make a copy of the facility bit mask provided by STFLE and use the copy
for the decision to apply an alternative.

Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390: correct some inline assembly constraints

Inline assembly code changed in this patch should really use "Q"
constraint "Memory reference without index register and with short
displacement". The kernel does not compile with kasan support enabled
otherwise (due to stack instrumentation).

Signed-off-by: Vasily Gorbik <gor@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

s390: remove all code using the access register mode

The vdso code for the getcpu() and the clock_gettime() call use the access
register mode to access the per-CPU vdso data page with the current code.

An alternative to the complicated AR mode is to use the secondary space
mode. This makes the vdso faster and quite a bit simpler. The downside is
that the uaccess code has to be changed quite a bit.

Which instructions are used depends on the machine and what kind of uaccess
operation is requested. The instruction dictates which ASCE value needs
to be loaded into %cr1 and %cr7.

The different cases:

* User copy with MVCOS for z10 and newer machines
The MVCOS instruction can copy between the primary space (aka user) and
the home space (aka kernel) directly. For set_fs(KERNEL_DS) the kernel
ASCE is loaded into %cr1. For set_fs(USER_DS) the user space is already
loaded in %cr1.

* User copy with MVCP/MVCS for older machines
To be able to execute the MVCP/MVCS instructions the kernel needs to
switch to primary mode. The control register %cr1 has to be set to the
kernel ASCE and %cr7 to either the kernel ASCE or the user ASCE dependent
on set_fs(KERNEL_DS) vs set_fs(USER_DS).

* Data access in the user address space for strnlen / futex
To use "normal" instruction with data from the user address space the
secondary space mode is used. The kernel needs to switch to primary mode,
%cr1 has to contain the kernel ASCE and %cr7 either the user ASCE or the
kernel ASCE, dependent on set_fs.

To load a new value into %cr1 or %cr7 is an expensive operation, the kernel
tries to be lazy about it. E.g. for multiple user copies in a row with
MVCP/MVCS the replacement of the vdso ASCE in %cr7 with the user ASCE is
done only once. On return to user space a CPU bit is checked that loads the
vdso ASCE again.

To enable and disable the data access via the secondary space two new
functions are added, enable_sacf_uaccess and disable_sacf_uaccess. The fact
that a context is in secondary space uaccess mode is stored in the
mm_segment_t value for the task. The code of an interrupt may use set_fs
as long as it returns to the previous state it got with get_fs with another
call to set_fs. The code in finish_arch_post_lock_switch simply has to do a
set_fs with the current mm_segment_t value for the task.

For CPUs with MVCOS:

CPU running in | %cr1 ASCE | %cr7 ASCE |
--------------------------------------|-----------|-----------|
user space | user | vdso |
kernel, USER_DS, normal-mode | user | vdso |
kernel, USER_DS, normal-mode, lazy | user | user |
kernel, USER_DS, sacf-mode | kernel | user |
kernel, KERNEL_DS, normal-mode | kernel | vdso |
kernel, KERNEL_DS, normal-mode, lazy | kernel | kernel |
kernel, KERNEL_DS, sacf-mode | kernel | kernel |

For CPUs without MVCOS:

CPU running in | %cr1 ASCE | %cr7 ASCE |
--------------------------------------|-----------|-----------|
user space | user | vdso |
kernel, USER_DS, normal-mode | user | vdso |
kernel, USER_DS, normal-mode lazy | kernel | user |
kernel, USER_DS, sacf-mode | kernel | user |
kernel, KERNEL_DS, normal-mode | kernel | vdso |
kernel, KERNEL_DS, normal-mode, lazy | kernel | kernel |
kernel, KERNEL_DS, sacf-mode | kernel | kernel |

The lines with "lazy" refer to the state after a copy via the secondary
space with a delayed reload of %cr1 and %cr7.

There are three hardware address spaces that can cause a DAT exception,
primary, secondary and home space. The exception can be related to
four different fault types: user space fault, vdso fault, kernel fault,
and the gmap faults.

Dependent on the set_fs state and normal vs. sacf mode there are a number
of fault combinations:

1) user address space fault via the primary ASCE
2) gmap address space fault via the primary ASCE
3) kernel address space fault via the primary ASCE for machines with
MVCOS and set_fs(KERNEL_DS)
4) vdso address space faults via the secondary ASCE with an invalid
address while running in secondary space in problem state
5) user address space fault via the secondary ASCE for user-copy
based on the secondary space mode, e.g. futex_ops or strnlen_user
6) kernel address space fault via the secondary ASCE for user-copy
with secondary space mode with set_fs(KERNEL_DS)
7) kernel address space fault via the primary ASCE for user-copy
with secondary space mode with set_fs(USER_DS) on machines without
MVCOS.
8) kernel address space fault via the home space ASCE

Replace user_space_fault() with a new function get_fault_type() that
can distinguish all four different fault types.

With these changes the futex atomic ops from the kernel and the
strnlen_user will get a little bit slower, as well as the old style
uaccess with MVCP/MVCS. All user accesses based on MVCOS will be as
fast as before. On the positive side, the user space vdso code is a
lot faster and Linux ceases to use the complicated AR mode.

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

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

s390/spinlock: introduce spinlock wait queueing

The queued spinlock code for s390 follows the principles of the common
code qspinlock implementation but with a few notable differences.

The format of the spinlock_t locking word differs, s390 needs to store
the logical CPU number of the lock holder in the spinlock_t to be able
to use the diagnose 9c directed yield hypervisor call.

The inline code sequences for spin_lock and spin_unlock are nice and
short. The inline portion of a spin_lock now typically looks like this:

lhi %r0,0 # 0 indicates an empty lock
l %r1,0x3a0 # CPU number + 1 from lowcore
cs %r0,%r1,<some_lock> # lock operation
jnz call_wait # on failure call wait function
locked:
...
call_wait:
la %r2,<some_lock>
brasl %r14,arch_spin_lock_wait
j locked

A spin_unlock is as simple as before:

lhi %r0,0
sth %r0,2(%r2) # unlock operation

After a CPU has queued itself it may not enable interrupts again for the
arch_spin_lock_flags() variant. The arch_spin_lock_wait_flags wait function
is removed.

To improve performance the code implements opportunistic lock stealing.
If the wait function finds a spinlock_t that indicates that the lock is
free but there are queued waiters, the CPU may steal the lock up to three
times without queueing itself. The lock stealing update the steal counter
in the lock word to prevent more than 3 steals. The counter is reset at
the time the CPU next in the queue successfully takes the lock.

While the queued spinlocks improve performance in a system with dedicated
CPUs, in a virtualized environment with continuously overcommitted CPUs
the queued spinlocks can have a negative effect on performance. This
is due to the fact that a queued CPU that is preempted by the hypervisor
will block the queue at some point even without holding the lock. With
the classic spinlock it does not matter if a CPU is preempted that waits
for the lock. Therefore use the queued spinlock code only if the system
runs with dedicated CPUs and fall back to classic spinlocks when running
with shared CPUs.

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

s390/time: add support for the TOD clock epoch extension

The TOD epoch extension adds 8 epoch bits to the TOD clock to provide
a continuous clock after 2042/09/17. The store-clock-extended (STCKE)
instruction will store the epoch index in the first byte of the
16 bytes stored by the instruction. The read_boot_clock64 and the
read_presistent_clock64 functions need to take the additional bits
into account to give the correct result after 2042/09/17.

The clock-comparator register will stay 64 bit wide. The comparison
of the clock-comparator with the TOD clock is limited to bytes
1 to 8 of the extended TOD format. To deal with the overflow problem
due to an epoch change the clock-comparator sign control in CR0 can
be used to switch the comparison of the 64-bit TOD clock with the
clock-comparator to a signed comparison.

The decision between the signed vs. unsigned clock-comparator
comparisons is done at boot time. Only if the TOD clock is in the
second half of a 142 year epoch the signed comparison is used.
This solves the epoch overflow issue as long as the machine is
booted at least once in an epoch.

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

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>

sched/cputime, s390: Implement delayed accounting of system time

The account_system_time() function is called with a cputime that
occurred while running in the kernel. The function detects which
context the CPU is currently running in and accounts the time to
the correct bucket. This forces the arch code to account the
cputime for hardirq and softirq immediately.

Such accounting function can be costly and perform unwelcome divisions
and multiplications, among others.

The arch code can delay the accounting for system time. For s390
the accounting is done once per timer tick and for each task switch.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
[ Rebase against latest linus tree and move account_system_index_scaled(). ]
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Wanpeng Li <wanpeng.li@hotmail.com>
Link: http://lkml.kernel.org/r/1483636310-6557-10-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

s390: move thread_info into task_struct

This is the s390 variant of commit 15f4eae70d36 ("x86: Move
thread_info into task_struct").

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

s390/preempt: move preempt_count to the lowcore

Convert s390 to use a field in the struct lowcore for the CPU
preemption count. It is a bit cheaper to access a lowcore field
compared to a thread_info variable and it removes the depencency
on a task related structure.

bloat-o-meter on the vmlinux image for the default configuration
(CONFIG_PREEMPT_NONE=y) reports a small reduction in text size:

add/remove: 0/0 grow/shrink: 18/578 up/down: 228/-5448 (-5220)

A larger improvement is achieved with the default configuration
but with CONFIG_PREEMPT=y and CONFIG_DEBUG_PREEMPT=n:

add/remove: 2/6 grow/shrink: 59/4477 up/down: 1618/-228762 (-227144)

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

s390/fpu: improve kernel_fpu_[begin|end]

In case of nested user of the FPU or vector registers in the kernel
the current code uses the mask of the FPU/vector registers of the
previous contexts to decide which registers to save and restore.
E.g. if the previous context used KERNEL_VXR_V0V7 and the next
context wants to use KERNEL_VXR_V24V31 the first 8 vector registers
are stored to the FPU state structure. But this is not necessary
as the next context does not use these registers.

Rework the FPU/vector register save and restore code. The new code
does a few things differently:
1) A lowcore field is used instead of a per-cpu variable.
2) The kernel_fpu_end function now has two parameters just like
kernel_fpu_begin. The register flags are required by both
functions to save / restore the minimal register set.
3) The inline functions kernel_fpu_begin/kernel_fpu_end now do the
update of the register masks. If the user space FPU registers
have already been stored neither save_fpu_regs nor the
__kernel_fpu_begin/__kernel_fpu_end functions have to be called
for the first context. In this case kernel_fpu_begin adds 7
instructions and kernel_fpu_end adds 4 instructions.
3) The inline assemblies in __kernel_fpu_begin / __kernel_fpu_end
to save / restore the vector registers are simplified a bit.

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

s390: rename struct _lowcore to struct lowcore

Finally get rid of the leading underscore. I tried this already two or
three years ago, however Michael Holzheu objected since this would
break the crash utility (again).

However Michael integrated support for the new name into the crash
utility back then, so it doesn't break if the name will be changed
now. So finally get rid of the ever confusing leading underscore.

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

s390/dump: cleanup CPU save area handling

Introduce save_area_alloc(), save_area_boot_cpu(), save_area_add_regs()
and save_area_add_vxrs to deal with storing the CPU state in case of a
system dump. Remove struct save_area and save_area_ext, and create a new
struct save_area as a local definition to arch/s390/kernel/crash_dump.c.
Copy each individual field from the hardware status area to the save area,
storing the minimum of required data.

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

s390/zcore: remove /sys/kernel/debug/zcore/mem

New versions of the SCSI dumper use the /dev/vmcore interface instead
of zcore mem. Remove the outdated interface.

Acked-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/zcore: copy vector registers into the image data

The /sys/kernel/debug/zcore/mem interface delivers the memory of the
old system with the CPU registers stored to the assigned locations in
each prefix page.

For the vector registers the prefix page of each CPU has an address of
a 1024 byte save area at 0x11b0. But the /sys/kernel/debug/zcore/mem
interface fails copy the vector registers saved at boot of the zfcpdump
kernel into the dump image.

Copy the saved vector registers of a CPU to the outout buffer if the
memory area that is read via /sys/kernel/debug/zcore/mem intersects
with the vector register save area of this CPU.

Acked-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/nmi: change type of mcck_interruption_code lowcore field

For some unknown reason the mcck_interruption_code field is defined
as array of two 32 bit values. Given that this actually is a 64 bit
field according to the architecture, change the type to u64.

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

s390/cpumf: rework program parameter setting to detect guest samples

The program parameter can be used to mark hardware samples with
some token. Previously, it was used to mark guest samples only.

Improve the program parameter doubleword by combining two parts,
the leftmost LPP part and the rightmost PID part. Set the PID
part for processes by using the task PID.
To distinguish host and guest samples for the kernel (PID part
is zero), the guest must always set the program paramater to a
non-zero value. Use the leftmost bit in the LPP part of the
program parameter to be able to detect guest kernel samples.

[brueckner@linux.vnet.ibm.com]: Split __LC_CURRENT and introduced
__LC_LPP. Corrected __LC_CURRENT users and adjusted assembler parts.
And updated the commit message accordingly.

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

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>

s390/ftrace,kprobes: allow to patch first instruction

If the function tracer is enabled, allow to set kprobes on the first
instruction of a function (which is the function trace caller):

If no kprobe is set handling of enabling and disabling function tracing
of a function simply patches the first instruction. Either it is a nop
(right now it's an unconditional branch, which skips the mcount block),
or it's a branch to the ftrace_caller() function.

If a kprobe is being placed on a function tracer calling instruction
we encode if we actually have a nop or branch in the remaining bytes
after the breakpoint instruction (illegal opcode).
This is possible, since the size of the instruction used for the nop
and branch is six bytes, while the size of the breakpoint is only
two bytes.
Therefore the first two bytes contain the illegal opcode and the last
four bytes contain either "0" for nop or "1" for branch. The kprobes
code will then execute/simulate the correct instruction.

Instruction patching for kprobes and function tracer is always done
with stop_machine(). Therefore we don't have any races where an
instruction is patched concurrently on a different cpu.
Besides that also the program check handler which executes the function
trace caller instruction won't be executed concurrently to any
stop_machine() execution.

This allows to keep full fault based kprobes handling which generates
correct pt_regs contents automatically.

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

s390/kdump: add support for vector extension

With this patch for kdump the s390 vector registers are stored into the
prepared save areas in the old kernel and into the REGSET_VX_LOW and
REGSET_VX_HIGH ELF notes for /proc/vmcore in the new kernel.

The NT_S390_VXRS_LOW note contains the lower halves of the first 16 vector
registers 0-15. The higher halves are stored in the floating point register
ELF note. The NT_S390_VXRS_HIGH contains the full vector registers 16-31.

The kernel provides a save area for storing vector register in case of
machine checks. A pointer to this save are is stored in the CPU lowcore
at offset 0x11b0. This save area is also used to save the registers for
kdump. In case of a dumped crashed kdump those areas are used to extract
the registers of the production system.

The vector registers for remote CPUs are stored using the "store additional
status at address" SIGP. For the dump CPU the vector registers are stored
with the VSTM instruction.

With this patch also zfcpdump stores the vector registers.

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

s390: add support for vector extension

The vector extension introduces 32 128-bit vector registers and a set of
instruction to operate on the vector registers.

The kernel can control the use of vector registers for the problem state
program with a bit in control register 0. Once enabled for a process the
kernel needs to retain the content of the vector registers on context
switch. The signal frame is extended to include the vector registers.
Two new register sets NT_S390_VXRS_LOW and NT_S390_VXRS_HIGH are added
to the regset interface for the debugger and core dumps.

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

s390/lowcore: replace lowcore irb array with a per-cpu variable

Remove the 96-byte irb array from the lowcore and create a per-cpu
variable instead. That way we will pick up any change in the definition
of the struct irb automatically.

Acked-By: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390/lowcore: reserve 96 bytes for IRB in lowcore

The IRB might be 96 bytes if the extended-I/O-measurement facility is
used. This feature is currently not used by Linux, but struct irb
already has the emw defined. So let's make the irb in lowcore match the
size of the internal data structure to be future proof.
We also have to add a pad, to correctly align the paste.

The bigger irb field also circumvents a bug in some QEMU versions that
always write the emw field on test subchannel and therefore destroy the
paste definitions of this CPU. Running under these QEMU version broke
some timing functions in the VDSO and all users of these functions,
e.g. some JREs.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Sebastian Ott <sebott@linux.vnet.ibm.com>
Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
Cc: stable@vger.kernel.org

s390: split TIF bits into CIF, PIF and TIF bits

The oi and ni instructions used in entry[64].S to set and clear bits
in the thread-flags are not guaranteed to be atomic in regard to other
CPUs. Split the TIF bits into CPU, pt_regs and thread-info specific
bits. Updates on the TIF bits are done with atomic instructions,
updates on CPU and pt_regs bits are done with non-atomic instructions.

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

s390/spinlock: optimize spinlock code sequence

Use lowcore constant to improve the code generated for spinlocks.

[ Martin Schwidefsky: patch breakdown and code beautification ]

Signed-off-by: Philipp Hachtmann <phacht@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

s390: rename and split lowcore field per_perc_atmid

per_perc_atmid is currently a two-byte field that combines two
fields, the PER code and the PER Addressing-and-Translation-Mode
Identification (ATMID)

Let's make them accessible indepently and also rename per_cause to
per_code.

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

s390: fix name of lowcore field at offset 0xa3

According to the Principles of Operation, at offset 0xA3
in the lowcore we have the "Architectural-Mode identification",
not an "access identification".

Signed-off-by: Jens Freimann <jfrei@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

s390: add support for transactional memory

Allow user-space processes to use transactional execution (TX).
If the TX facility is available user space programs can use
transactions for fine-grained serialization based on the data
objects that are referenced during a transaction. This is
useful for lockless data structures and speculative compiler
optimizations.

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

s390/comments: unify copyright messages and remove file names

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 <heiko.carstens@de.ibm.com>

s390/smp: make absolute lowcore / cpu restart parameter accesses more robust

Setting the cpu restart parameters is done in three different fashions:
- directly setting the four parameters individually
- copying the four parameters with memcpy (using 4 * sizeof(long))
- copying the four parameters using a private structure

In addition code in entry*.S relies on a certain order of the restart
members of struct _lowcore.

Make all of this more robust to future changes by adding a
mem_absolute_assign(dest, val) define, which assigns val to dest
using absolute addressing mode. Also the load multiple instructions
in entry*.S have been split into separate load instruction so the
order of the struct _lowcore members doesn't matter anymore.

In addition move the prototypes of memcpy_real/absolute from uaccess.h
to processor.h. These memcpy* variants are not related to uaccess at all.
string.h doesn't seem to match as well, so lets use processor.h.

Also replace the eight byte array in struct _lowcore which represents a
misaliged u64 with a u64. The compiler will always create code that
handles the misaligned u64 correctly.

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

[S390] Ensure that vmcore_info pointer is never accessed directly

Because the vmcore_info pointer is not 8 byte aligned it never should
not be accessed directly. The reason is that the compiler assumes that
64 bit pointer are always double word aligned. To ensure save access,
the vmcore_info type in struct lowcore is changed from u64 to an u8[8]
array and a comment is added.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] kernel: Add OS info memory interface

In order to allow kdump based stand-alone dump, some information
has to be passed from the old kernel to the new dump kernel. This
is done via a the struct "os_info" that contains the following fields:
* crashkernel base and size
* reipl block
* vmcoreinfo
* init function
A pointer to os_info is stored at a well known storage location
and the whole structure as well as all fields are secured with
checksums.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] rework smp code

Define struct pcpu and merge some of the NR_CPUS arrays into it, including
__cpu_logical_map, current_set and smp_cpu_state. Split smp related
functions to those operating on physical cpus and the functions operating
on a logical cpu number. Make the functions for physical cpus use a
pointer to a struct pcpu. This hides the knowledge about cpu addresses in
smp.c, entry[64].S and swsusp_asm64.S, thus remove the sigp.h header.

The PSW restart mechanism is used to start secondary cpus, calling a
function on an online cpu, calling a function on the ipl cpu, and for
the nmi signal. Replace the different assembler functions with a
single function restart_int_handler. The new entry point calls a function
whose pointer is stored in the lowcore of the target cpu and it can wait
for the source cpu to stop. This covers all existing use cases.

Overall the code is now simpler and there are ~380 lines less code.

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

[S390] rename lowcore field

The 16 bit value at the lowcore location with offset 0x84 is the
cpu address that is associated with an external interrupt. Rename
the field from cpu_addr to ext_cpu_addr to make that clear.

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

[S390] entry[64].S improvements

Another round of cleanup for entry[64].S, in particular the program check
handler looks more reasonable now. The code size for the 31 bit kernel
has been reduced by 616 byte and by 528 byte for the 64 bit version.
Even better the code is a bit faster as well.

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

[S390] kvm: move cmf host id constant out of lowcore

There is no reason for the cpu-measurement-facility host id constant to
reside in the lowcore where space is precious. Use an entry in the literal
pool in HANDLE_SIE_INTERCEPT and a stack slot in sie64a.
While we are at it replace the id -1 with 0 to indicate host execution.

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

[S390] lowcore cleanup

Remove the save_area_64 field from the 0xe00 - 0xf00 area in the lowcore.
Use a free slot in the save_area array instead.

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

[S390] Export vmcoreinfo note

This patch defines for s390 an ABI defined pointer to the vmcoreinfo note at
a well known address. With this patch tools are able to find this information
in dumps created by stand-alone or hypervisor dump tools.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] Add PSW restart shutdown trigger

With this patch a new S390 shutdown trigger "restart" is added. If under
z/VM "systerm restart" is entered or under the HMC the "PSW restart" button
is pressed, the PSW located at 0 (31 bit) or 0x1a0 (64 bit) bit is loaded.
Now we execute do_restart() that processes the restart action that is
defined under /sys/firmware/shutdown_actions/on_restart. Currently the
following actions are possible: reipl (default), stop, vmcmd, dump, and
dump_reipl.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

[S390] kvm guest address space mapping

Add code that allows KVM to control the virtual memory layout that
is seen by a guest. The guest address space uses a second page table
that shares the last level pte-tables with the process page table.
If a page is unmapped from the process page table it is automatically
unmapped from the guest page table as well.

The guest address space mapping starts out empty, KVM can map any
individual 1MB segments from the process virtual memory to any 1MB
aligned location in the guest virtual memory. If a target segment in
the process virtual memory does not exist or is unmapped while a
guest mapping exists the desired target address is stored as an
invalid segment table entry in the guest page table.
The population of the guest page table is fault driven.

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

[S390] pfault: cpu hotplug vs missing completion interrupts

On cpu hot remove a PFAULT CANCEL command is sent to the hypervisor
which in turn will cancel all outstanding pfault requests that have
been issued on that cpu (the same happens with a SIGP cpu reset).

The result is that we end up with uninterruptible processes where
the interrupt that would wake up these processes never arrives.

In order to solve this all processes which wait for a pfault
completion interrupt get woken up after a cpu hot remove. The worst
case that could happen is that they fault again and in turn need to
wait again.

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

[S390] Remove data execution protection

The noexec support on s390 does not rely on a bit in the page table
entry but utilizes the secondary space mode to distinguish between
memory accesses for instructions vs. data. The noexec code relies
on the assumption that the cpu will always use the secondary space
page table for data accesses while it is running in the secondary
space mode. Up to the z9-109 class machines this has been the case.
Unfortunately this is not true anymore with z10 and later machines.
The load-relative-long instructions lrl, lgrl and lgfrl access the
memory operand using the same addressing-space mode that has been
used to fetch the instruction.
This breaks the noexec mode for all user space binaries compiled
with march=z10 or later. The only option is to remove the current
noexec support.

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

[S390] cleanup facility list handling

Store the facility list once at system startup with stfl/stfle and
reuse the result for all facility tests.

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

[S390] virtualization aware cpu measurement

Use the SPP instruction to set a tag on entry to / exit of the virtual
machine context. This allows the cpu measurement facility to distinguish
the samples from the host and the different guests.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>

[S390] idle time accounting vs. machine checks

A machine check can interrupt the i/o and external interrupt handler
anytime. If the machine check occurs while the interrupt handler is
waking up from idle vtime_start_cpu can get executed a second time
and the int_clock / async_enter_timer values in the lowcore get
clobbered. This can confuse the cpu time accounting.
To fix this problem two changes are needed. First the machine check
handler has to use its own copies of int_clock and async_enter_timer,
named mcck_clock and mcck_enter_timer. Second the nested execution
of vtime_start_cpu has to be prevented. This is done in s390_idle_check
by checking the wait bit in the program status word.

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

[S390] More cleanup for struct _lowcore

Remove cpu_id from lowcore and replace addr_t with __u64.

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

[S390] Cleanup struct _lowcore usage and defines.

Use asm offsets to make sure the offset defines to struct _lowcore and
its layout don't get out of sync.
Also add a BUILD_BUG_ON() which checks that the size of the structure
is sane.
And while being at it change those sites which use odd casts to access
the current lowcore. These should use S390_lowcore instead.

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

[S390] smp: rename and add lowcore defines

Rename __LC_RESTART_PSW to __LC_RST_NEW_PSW, add a define for the
missing 32 bit variant and the missing old PSWs.

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

[S390] zfcpdump: remove cross arch dump support

Remove support to be able to dump 31 bit systems with a 64 bit dumper.
This is mostly useless since no distro ships 31 bit kernels together
with a 64 bit dumper.
We also get rid of a bit of hacky code.

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

[S390] Fix struct _lowcore layout.

Offsets and sizes are wrong for 32 bit.
Got broken with 866ba284 "[S390] cleanup lowcore.h".

Reported-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] hibernate: Do real CPU swap at resume time

Currently, when the physical resume CPU is not equal to the physical suspend
CPU, we swap the CPUs logically, by modifying the logical/physical CPU mapping.
This has two major drawbacks: First the change is visible from user space (e.g.
CPU sysfs files) and second it is hard to ensure that nowhere in the kernel
the physical CPU ID is stored before suspend.
To fix this, we now really swap the physical CPUs, if the resume CPU is not
the pysical suspend CPU. We restart the suspend CPU and stop the resume CPU
using SIGP restart and SIGP stop. If the suspend CPU is no longer available,
we write a message and load a disabled wait PSW.

Signed-off-by: Michael Holzheu <michael.holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] hibernate: make sure pfn_is_nosave handles lowcore pages

pfn_is_nosave doesn't return the correct value for the second lowcore
page if lowcore protection is enabled. Make sure it always returns
the correct value.

While at it simplify the whole thing.
NSS special handling is done by the tprot check like it already works
for DCSS as well. So remove the extra code for NSS.

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

[S390] smp: introduce LC_ORDER and simplify lowcore handling

Removes a couple of simple code duplications. But before I have to do
this again, just simplify it.

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

[S390] Get rid of cpuid.h header file.

Merge cpuid.h header file into cpu.h.
While at it convert from typedef to struct declaration and also
convert cio code to use proper lowcore structure instead of casts.

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

[S390] ftrace: add dynamic ftrace support

Dynamic ftrace support for s390.

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

[S390] use facility list for cpu type safety check

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

[S390] s390: move machine flags to lowcore

Currently the storage of the machine flags is a globally exported unsigned
long long variable. By moving the storage location into the lowcore struct we
allow assembler code to check machine_flags directly even without needing a
register. Addtionally the lowcore and therefore the machine flags too will be
in cache most of the time.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[S390] cleanup lowcore.h

The lowcore.h header has quite a lot of whitespace damage and a rather
wild collection of entries. Remove all that whitespace and tidy up the
order of the lowcore fields.

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

[S390] eliminate ipl_device from lowcore

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

[S390] eliminate cpuinfo_S390 structure

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

[S390] Fix comments in lowcore structure

This patch fixes two addresses in the comments for the
lowcore structure. Looks like an copy-paste bug.

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

[S390] Automatic IPL after dump

Provide new shutdown action "dump_reipl" for automatic ipl after dump.

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

[S390] vdso: fix per cpu vdso pointer in lowcore

The vdso_per_cpu_data entry in the lowcore structure uses __u32
instead of __u64. If the data page is above 4GB the pointer is
truncated and the kernel crashes.

Reported-by: Mijo Safradin <mijo@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

[PATCH] fast vdso implementation for CLOCK_THREAD_CPUTIME_ID

The extract cpu time instruction (ectg) instruction allows the user
process to get the current thread cputime without calling into the
kernel. The code that uses the instruction needs to switch to the
access registers mode to get access to the per-cpu info page that
contains the two base values that are needed to calculate the current
cputime from the CPU timer with the ectg instruction.

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

[PATCH] improve precision of process accounting.

The unit of the cputime accouting values that are stored per process is
currently a microsecond. The CPU timer has a maximum granularity of
2**-12 microseconds. There is no benefit in storing the per process values
in the lesser precision and there is the disadvantage that the backend
has to do the rounding to microseconds. The better solution is to use
the maximum granularity of the CPU timer as cputime unit.

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

[S390] move include/asm-s390 to arch/s390/include/asm

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