s390/ptrace: add missing linux/const.h include

Adrian Reber reported the following CRIU build bug after
commit b8af5999779d ("s390/ptrace: make all psw related
defines also available for asm"):

compel/arch/s390/src/lib/infect.c: In function 'arch_can_dump_task':
compel/arch/s390/src/lib/infect.c:523:25: error: 'UL' undeclared (first use in this function)
523 | if (psw->mask & PSW_MASK_RI) {
| ^~~~~~~~~~~

Add the missing linux/const.h include to fix this.

Reported-by: Adrian Reber <areber@redhat.com>
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2225745
Link: https://github.com/checkpoint-restore/criu/pull/2232
Tested-by: Adrian Reber <areber@redhat.com>
Fixes: b8af5999779d ("s390/ptrace: make all psw related defines also available for asm")
Link: https://lore.kernel.org/r/20230731183926.330932-1-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

s390/ptrace: make all psw related defines also available for asm

Use the _AC() macro to make all psw related defines also available for
assembler files.

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

s390/ptrace: remove PSW_DEFAULT_KEY from uapi

Move PSW_DEFAULT_KEY from uapi/asm/ptrace.h to asm/ptrace.h. This is
possible, since it depends on PAGE_DEFAULT_ACC which is not part of
uapi. Or in other words: this define cannot be used without error.

Therefore remove it from uapi.

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

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/uapi: correct whitespace & coding style in asm/ptrace.h

Correct whitespace and coding style issues in the s390 asm/ptrace.h
uapi header file. This is preparatory work to copy it to the tools/
directory for inclusion by selftests and perf.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

s390/bpf: correct broken uapi for BPF_PROG_TYPE_PERF_EVENT program type

To mitigate and correct the broken uapi for the BPF_PROG_TYPE_PERF_EVENT
program type, introduce a user_pt_regs structure (similar to arm64) that
exports parts from the beginnig of the pt_regs structure.

The export must start with the beginning of the pt_regs structure because
to correctly calculate BPF prologues for perf (regs_query_register_offset()).

For BPF_PROG_TYPE_PERF_EVENT program types, the BPF program is then passed
a user_pt_regs structure.

Note: Depending on future changes to the s390 pt_regs structure, consider
the user_pt_regs structure to be stable for a particular kernel version
only. (Of course, s390 tries to ensure keep it stable as much as possible.)

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Reviewed-and-tested-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

License cleanup: add SPDX license identifier to uapi header files with no license

Many user space API headers are missing licensing information, which
makes it hard for compliance tools to determine the correct license.

By default are files without license information under the default
license of the kernel, which is GPLV2. Marking them GPLV2 would exclude
them from being included in non GPLV2 code, which is obviously not
intended. The user space API headers fall under the syscall exception
which is in the kernels COPYING file:

NOTE! This copyright does *not* cover user programs that use kernel
services by normal system calls - this is merely considered normal use
of the kernel, and does *not* fall under the heading of "derived work".

otherwise syscall usage would not be possible.

Update the files which contain no license information with an SPDX
license identifier. The chosen identifier is 'GPL-2.0 WITH
Linux-syscall-note' which is the officially assigned identifier for the
Linux syscall exception. SPDX license identifiers are 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. See the previous patch in this series for the
methodology of how this patch was researched.

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/ptrace: clarify bits in the per_struct

The bits single_step and instruction_fetch lost their meaning
with git commit 5e9a26928f550157 "[S390] ptrace cleanup".
Clarify the comment for these two bits.

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

s390/ptrace: add support for PTRACE_SINGLEBLOCK

The PTRACE_SINGLEBLOCK option is used to get control whenever
the inferior has executed a successful branch. The PER option to
implement block stepping is successful-branching event, bit 32
in the PER-event mask.

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

s390: fix handling of runtime instrumentation psw bit

Fix the following bugs:
- When returning from a signal the signal handler copies the saved psw mask
from user space and uses parts of it. Especially it restores the RI bit
unconditionally. If however the machine doesn't support RI, or RI is
disabled for the task, the last lpswe instruction which returns to user
space will generate a specification exception.
To fix this check if the RI bit is allowed to be set and kill the task
if not.
- In the compat mode signal handler code the RI bit of the psw mask gets
propagated to the mask of the return psw: if user space enables RI in the
signal handler, RI will also be enabled after the signal handler is
finished.
This is a different behaviour than with 64 bit tasks. So change this to
match the 64 bit semantics, which restores the original RI bit value.
- Fix similar oddities within the ptrace code as well.

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

s390: fix save and restore of the floating-point-control register

The FPC_VALID_MASK has been used to check the validity of the value
to be loaded into the floating-point-control register. With the
introduction of the floating-point extension facility and the
decimal-floating-point additional bits have been defined which need
to be checked in a non straight forward way. So far these bits have
been ignored which can cause an incorrect results for decimal-
floating-point operations, e.g. an incorrect rounding mode to be
set after signal return.

The static check with the FPC_VALID_MASK is replaced with a trial
load of the floating-point-control value, see test_fp_ctl.

In addition an information leak with the padding word between the
floating-point-control word and the floating-point registers in
the s390_fp_regs is fixed.

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

s390/ptrace: PTRACE_TE_ABORT_RAND

The patch implements a s390 specific ptrace request
PTRACE_TE_ABORT_RAND to modify the randomness of spontaneous
aborts of memory transactions of the transaction execution
facility. The data argument of the ptrace request is used to
specify the levels of randomness, 0 for normal operation, 1 to
abort every transaction at a random instruction, and 2 to abort
a random transaction at a random instruction. The default is 0
for normal operation.

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

s390/compat: remove ptrace compat definitions from uapi header file

The compat definitions are not part of the uapi. So move them to
s390's private compat header file.

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

s390/signal: set correct address space control

If user space is running in primary mode it can switch to secondary
or access register mode, this is used e.g. in the clock_gettime code
of the vdso. If a signal is delivered to the user space process while
it has been running in access register mode the signal handler is
executed in access register mode as well which will result in a crash
most of the time.

Set the address space control bits in the PSW to the default for the
execution of the signal handler and make sure that the previous
address space control is restored on signal return. Take care
that user space can not switch to the kernel address space by
modifying the registers in the signal frame.

Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

UAPI: (Scripted) Disintegrate arch/s390/include/asm

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Dave Jones <davej@redhat.com>