linux.git/arch/s390/kernel/Makefile, branch v5.19

s390: simplify early program check handler

2022-05-25T09:46:02+00:00

Due to historic reasons the base program check handler calls a
configurable function. Given that there is only the early program
check handler left, simplify the code by directly calling that
function.

The only other user was removed with commit d485235b0054 ("s390:
assume diag308 set always works").

Also rename all functions and the asm file to reflect this.

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

s390/pai: add support for cryptography counters

2022-05-09T09:50:01+00:00

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

s390/kprobes: Avoid additional kprobe in kretprobe handling

2022-03-10T14:58:17+00:00

So far, s390 registered a krobe on __kretprobe_trampoline which is
called everytime a kretprobe fires. This kprobe would then determine
the correct return address and adjust the psw accordingly, such that
the kretprobe would branch to the appropriate address after completion.

Some other archs handle kretprobes without such an additional kprobe.
This approach is adopted to s390 with this patch.
Furthermore, the __kretprobe_trampoline now uses an assembler function
to correctly gather the register and psw content to be passed to the
registered kretprobe handler as struct pt_regs. After completion, the
register content and the psw are set based on the contents of said
pt_regs struct.
Note that a change to the psw address in struct pt_regs will not have
an impact, as the probe will still return to the original return
address of the probed function.
The return address is now recovered by using the appropriate function
arch_kretprobe_fixup_return.

The no longer needed kprobe is removed.

Reviewed-by: Vasily Gorbik 
Signed-off-by: Tobias Huschle 
Signed-off-by: Vasily Gorbik

arch: Make ARCH_STACKWALK independent of STACKTRACE

2021-12-10T14:06:03+00:00

Make arch_stack_walk() available for ARCH_STACKWALK architectures
without it being entangled in STACKTRACE.

Link: https://lore.kernel.org/lkml/20211022152104.356586621@infradead.org/
Signed-off-by: Peter Zijlstra (Intel) 
[Mark: rebase, drop unnecessary arm change]
Signed-off-by: Mark Rutland 
Cc: Albert Ou 
Cc: Borislav Petkov 
Cc: Christian Borntraeger 
Cc: Dave Hansen 
Cc: Heiko Carstens 
Cc: Ingo Molnar 
Cc: Michael Ellerman 
Cc: Palmer Dabbelt 
Cc: Paul Walmsley 
Cc: Thomas Gleixner 
Cc: Vasily Gorbik 
Link: https://lore.kernel.org/r/20211129142849.3056714-2-mark.rutland@arm.com
Signed-off-by: Catalin Marinas

s390: rename dma section to amode31

2021-08-05T12:10:53+00:00

The dma section name is confusing, since the code which resides within
that section has nothing to do with direct memory access.  Instead the
limitation is that the code has to run in 31 bit addressing mode, and
therefore has to reside below 2GB.  So the name was chosen since
ZONE_DMA is the same region.

To reduce confusion rename the section to amode31, which hopefully
describes better what this is about.

Note: this will also change vmcoreinfo strings
- SDMA=... gets renamed to SAMODE31=...
- EDMA=... gets renamed to EAMODE31=...

Acked-by: Vasily Gorbik 
Reviewed-by: Alexander Egorenkov 
Signed-off-by: Heiko Carstens

s390/boot: move dma sections from decompressor to decompressed kernel

2021-07-27T07:39:17+00:00

This change simplifies the task of making the decompressor relocatable.

The decompressor's image contains special DMA sections between _sdma and
_edma. This DMA segment is loaded at boot as part of the decompressor and
then simply handed over to the decompressed kernel. The decompressor itself
never uses it in any way. The primary reason for this is the need to keep
the aforementioned DMA segment below 2GB which is required by architecture,
and because the decompressor is always loaded at a fixed low physical
address, it is guaranteed that the DMA region will not cross the 2GB
memory limit. If the DMA region had been placed in the decompressed kernel,
then KASLR would make this guarantee impossible to fulfill or it would
be restricted to the first 2GB of memory address space.

This commit moves all DMA sections between _sdma and _edma from
the decompressor's image to the decompressed kernel's image. The complete
DMA region is placed in the init section of the decompressed kernel and
immediately relocated below 2GB at start-up before it is needed by other
parts of the decompressed kernel. The relocation of the DMA region happens
even if the decompressed kernel is already located below 2GB in order
to keep the first implementation simple. The relocation should not have
any noticeable impact on boot time because the DMA segment is only a couple
of pages.

After relocating the DMA sections, the kernel has to fix all references
which point into it. In order to automate this, place all variables
pointing into the DMA sections in a special .dma.refs section. All such
variables must be defined using the new __dma_ref macro. Only variables
containing addresses within the DMA sections must be placed in the new
.dma.refs section.

Furthermore, move the initialization of control registers from
the decompressor to the decompressed kernel because some control registers
reference tables that must be placed in the DMA data section to
guarantee that their addresses are below 2G. Because the decompressed
kernel relocates the DMA sections at startup, the content of control
registers CR2, CR5 and CR15 must be updated with new addresses after
the relocation. The decompressed kernel initializes all control registers
early at boot and then updates the content of CR2, CR5 and CR15
as soon as the DMA relocation has occurred. This practically reverts
the commit a80313ff91ab ("s390/kernel: introduce .dma sections").

Signed-off-by: Alexander Egorenkov 
Acked-by: Heiko Carstens 
Signed-off-by: Heiko Carstens

s390/vdso: add minimal compat vdso

2021-07-08T13:37:28+00:00

Add a small vdso for 31 bit compat application that provides
trampolines for calls to sigreturn,rt_sigreturn,syscall_restart.
This is requird for moving these syscalls away from the signal
frame to the vdso. Note that this patch effectively disables
CONFIG_COMPAT when using clang to compile the kernel. clang
doesn't support 31 bit mode.

We want to redirect sigreturn and restart_syscall to the vdso. However,
the kernel cannot parse the ELF vdso file, so we need to generate header
files which contain the offsets of the syscall instructions in the vdso
page.

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

s390/cpumf: Allow concurrent access for CPU Measurement Counter Facility

2021-07-05T10:44:23+00:00

Commit cf6acb8bdb1d ("s390/cpumf: Add support for complete counter set extraction")
allows access to the CPU Measurement Counter Facility via character
device /dev/hwctr. The access was exclusive via this device or
via perf_event_open() system call. Only one path at a time was
permitted. The CPU Measurement Counter Facility device driver blocked
access to other processes.

This patch removes this restriction and allows concurrent access to
the CPU Measurement Counter Facility from multiple processes at the same
time via perf_event_open() SVC and via /dev/hwctr device. The access
via /dev/hwctr device is still exclusive, only one process is allowed to
access this device.

This patch
- moves the /dev/hwctr device access from file perf_cpum_cf_diag.c.
  to file perf_cpum_cf.c.
- use only one trace buffer .../s390dbf/cpum_cf.
- remove cfset_csd structure and includes its members it into the
  structure cpu_cf_events. This results in one data structure and
  simplifies the access.
- rework function familiy ctr_set_enable, ctr_set_disable, ctr_set_start
  and ctr_set_stop which operate on a counter set number.
  Now they operate on a counter set bit mask.
- move CF_DIAG event functionality to file perf_cpum_cf.c. It now
  contains the complete functionality of the CPU Measurement Counter
  Facility:
  - Performance measurement support for counters using perf stat.
  - Support for complete counter set extraction with device /dev/hwctr.
  - Support for counter set extraction event CF_DIAG attached to
    samples using perf record.
- removes file perf_cpum_cf_diag.c

Signed-off-by: Thomas Richter 
Reviewed-by: Sumanth Korikkar 
Signed-off-by: Vasily Gorbik

s390/traps: convert pgm_check.S to C

2021-04-12T10:46:41+00:00

Convert the program check table to C. Which allows to get rid of yet
another assembler file, and also enables proper type checking for the
table.

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

s390: convert to generic entry

2021-01-19T11:29:26+00:00

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 
Signed-off-by: Vasily Gorbik