linux.git/arch/s390/kernel/entry.S, branch v5.19

s390/mcck: isolate SIE instruction when setting CIF_MCCK_GUEST flag

2022-06-01T10:03:16+00:00

Commit d768bd892fc8 ("s390: add options to change branch prediction
behaviour for the kernel") introduced .Lsie_exit label - supposedly
to fence off SIE instruction. However, the corresponding address
range length .Lsie_crit_mcck_length was not updated, which led to
BPON code potentionally marked with CIF_MCCK_GUEST flag.

Both .Lsie_exit and .Lsie_crit_mcck_length were removed with commit
0b0ed657fe00 ("s390: remove critical section cleanup from entry.S"),
but the issue persisted - currently BPOFF and BPENTER macros might
get wrongly considered by the machine check handler as a guest.

Fixes: d768bd892fc8 ("s390: add options to change branch prediction behaviour for the kernel")
Reviewed-by: Sven Schnelle 
Reviewed-by: Christian Borntraeger 
Signed-off-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens

s390: generate register offsets into pt_regs automatically

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

Use asm offsets method to generate register offsets into pt_regs,
instead of open-coding at several places.

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

s390/entry: workaround llvm's IAS limitations

2022-05-17T13:16:28+00:00

llvm's integrated assembler cannot handle immediate values which are
calculated with two local labels:

:3:13: error: invalid operand for instruction
 clgfi %r14,.Lsie_done - .Lsie_gmap

Workaround this by adding clang specific code which reads the specific
value from memory. Since this code is within the hot paths of the kernel
and adds an additional memory reference, keep the original code, and add
ifdef'ed code.

Acked-by: Alexander Gordeev 
Link: https://lore.kernel.org/r/20220511120532.2228616-5-hca@linux.ibm.com
Signed-off-by: Heiko Carstens

s390/alternatives: provide identical sized orginal/alternative sequences

2022-05-17T13:16:28+00:00

Explicitly provide identical sized original/alternative instruction
sequences. This way there is no need for the s390 specific alternatives
infrastructure to generate padding sequences.
The code which generates such sequences will be removed with a follow on
patch.

Acked-by: Vasily Gorbik 
Tested-by: Nathan Chancellor 
Tested-by: Nick Desaulniers 
Link: https://lore.kernel.org/r/20220511120532.2228616-2-hca@linux.ibm.com
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/entry: remove broken and not needed code

2022-05-06T18:45:15+00:00

LLVM's integrated assembler reports the following error when compiling
entry.S:

:38:5: error: unknown token in expression
 tm %r8,0x0001 # coming from user space?

The correct instruction would have been tmhh instead of tm.
The current code is doing nothing, since (with gas) it get's
translated to a tm instruction which reads from real address 8, which
again contains always zero, and therefore the conditional code is
never executed.
Note that due to the missing displacement gas translates "%r8" into
"8(%r0)".

Also code inspection reveals that this conditional code is not needed.
Therefore remove it.

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

s390/alternatives: use insn format for new instructions

2022-03-27T20:18:39+00:00

Use insn format with instruction format specifier instead of plain
longs. This way it is also more obvious that code instead of data is
generated.

The generated code is identical.

Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: convert ".insn" encoding to instruction names

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

With z10 as minimum supported machine generation many ".insn" encodings
could be now converted to instruction names. There are couple of exceptions
- stfle is used from the als code built for z900 and cannot be converted
- few ".insn" directives encode unsupported instruction formats

The generated code is identical before/after this change.

Acked-by: Ilya Leoshkevich 
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: assume stckf is always present

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

With z10 as minimum supported machine generation the store-clock-fast
facility (25) is always present and checked in als code.
Drop alternatives and always use stckf.

Acked-by: Ilya Leoshkevich 
Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/extable: move EX_TABLE define to asm-extable.h

2022-03-07T23:33:00+00:00

Follow arm64 and riscv and move the EX_TABLE define to asm-extable.h
which is a lot less generic than the current linkage.h.

Also make sure that all files which contain EX_TABLE usages actually
include the new header file. This should make sure that the files
always compile and there won't be any random compile breakage due to
other header file dependencies.

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