linux.git/arch/s390/include/asm/processor.h, branch v6.12

s390/smp: Add cpu capacities

2024-08-29T20:56:35+00:00

Linux scheduler allows architectures to assign capacity values to
individual CPUs. This hints scheduler the performance difference between
CPUs and allows more efficient task distribution them. Implement
helper methods to set and get CPU capacities for s390. This is
particularly helpful in vertical polarization configurations of LPARs.
On vertical polarization an LPARs CPUs can get different polarization
values depending on the CEC configuration. CPUs with different
polarization values can perform different from each other, using CPU
capacities this can be reflected to linux scheduler.

Acked-by: Vasily Gorbik 
Signed-off-by: Mete Durlu 
Signed-off-by: Vasily Gorbik

s390/entry: Move SIE indicator flag to thread info

2024-07-23T14:02:31+00:00

CIF_SIE indicates if a thread is running in SIE context. This is the
state of a thread and not the CPU. Therefore move this indicator to
thread info.

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

s390/nospec: Push down alternative handling

2024-07-23T14:02:31+00:00

The nospec implementation is deeply integrated into the alternatives
code: only for nospec an alternative facility list is implemented and
used by the alternative code, while it is modified by nospec specific
needs.

Push down the nospec alternative handling into the nospec by
introducing a new alternative type and a specific nospec callback to
decide if alternatives should be applied.

Also introduce a new global nobp variable which together with facility
82 can be used to decide if nobp is enabled or not.

Acked-by: Alexander Gordeev 
Tested-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/alternatives: Rework to allow for callbacks

2024-07-23T14:02:31+00:00

Rework alternatives to allow for callbacks. With this every
alternative entry has additional data encoded:

- When (aka context) an alternative is supposed to be applied

- The type of an alternative, which allows for type specific handling
  and callbacks

- Extra type specific payload (patch information), which can be passed
  to callbacks in order to decide if an alternative should be applied
  or not

With this only the "late" context is implemented, which means there is
no change to the previous behaviour. All code is just converted to the
more generic new infrastructure.

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

s390: Move CIF flags to struct pcpu

2024-07-23T14:02:31+00:00

To allow testing flags for offline CPUs, move the CIF flags
to struct pcpu. To avoid having to calculate the array index
for each access, add a pointer to the pcpu member for the current
cpu to lowcore.

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

s390: Replace S390_lowcore by get_lowcore()

2024-06-18T15:01:33+00:00

Replace all S390_lowcore usages in arch/s390/ by get_lowcore().

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

s390: Mark psw in __load_psw_mask() as __unitialized

2024-05-14T11:37:08+00:00

Without __unitialized, the following code is generated when
INIT_STACK_ALL_ZERO is enabled:

86: d7 0f f0 a0 f0 a0     xc      160(16,%r15), 160(%r15)
8c: e3 40 f0 a0 00 24     stg     %r4, 160(%r15)
92: c0 10 00 00 00 08     larl    %r1, 0xa2
98: e3 10 f0 a8 00 24     stg     %r1, 168(%r15)
9e: b2 b2 f0 a0           lpswe   160(%r15)

The xc is not adding any security because psw is fully initialized
with the following instructions. Add __unitialized to the psw
definitiation to avoid the superfluous clearing of psw.

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

s390/idle: Rewrite psw_idle() in C

2024-05-14T11:37:07+00:00

To ease maintenance and further enhancements, convert
the psw_idle() function to C.

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

s390/stackstrace: Detect vdso stack frames

2024-05-14T11:37:07+00:00

Clear the backchain of the extra stack frame added by the vdso user wrapper
code. This allows the user stack walker to detect and skip the non-standard
stack frame. Without this an incorrect instruction pointer would be added
to stack traces, and stack frame walking would be continued with a more or
less random back chain.

Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support")
Reviewed-by: Jens Remus 
Signed-off-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev

s390/entry: add CIF_SIE flag and remove sie64a() address check

2024-03-17T18:08:49+00:00

When a program check, interrupt or machine check is triggered, the
PSW address is compared to a certain range of the sie64a() function
to figure out whether SIE was interrupted and a cleanup of SIE is
needed.

This doesn't work with kprobes: If kprobes probes an instruction, it
copies the instruction to the kprobes instruction page and overwrites the
original instruction with an undefind instruction (Opcode 00). When this
instruction is hit later, kprobes single-steps the instruction on the
kprobes_instruction page.

However, if this instruction is a relative branch instruction it will now
point to a different location in memory due to being moved to the kprobes
instruction page. If the new branch target points into sie64a() the kernel
assumes it interrupted SIE when processing the breakpoint and will crash
trying to access the SIE control block.

Instead of comparing the address, introduce a new CIF_SIE flag which
indicates whether SIE was interrupted.

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