kernel/linux.git/arch/s390/include/asm/spinlock.h, branch linux-7.0.y

s390: Remove superfluous newlines from inline assemblies

2025-09-29T11:52:08+00:00

Remove superfluous newlines from inline assemblies. Compilers use the number of lines of inline assemblies as heuristic for the complexity and inline decisions. Therefore inline assemblies should only contain as many lines as required. A lot of inline assemblies contain a superfluous newline for the last line. Remove such newlines to improve compiler inlining decisions. Suggested-by: Juergen Christ Signed-off-by: Heiko Carstens Reviewed-by: Alexander Gordeev Reviewed-by: Juergen Christ Signed-off-by: Alexander Gordeev

s390/spinlock: Implement SPINLOCK_LOCKVAL with inline assembly

2025-03-18T16:13:04+00:00

Implement SPINLOCK_LOCKVAL with an inline assembly, which makes use of the ALTERNATIVE macro, to read spinlock_lockval from lowcore. Provide an alternative instruction with a different offset in case lowcore is relocated. This replaces sequences of two instructions with one instruction. Before: 10602a: a7 78 00 00 lhi %r7,0 10602e: a5 8e 00 00 llilh %r8,0 106032: 58 d0 83 ac l %r13,940(%r8) 106036: ba 7d b5 80 cs %r7,%r13,1408(%r11) After: 10602a: a7 88 00 00 lhi %r8,0 10602e: e3 70 03 ac 00 58 ly %r7,940 106034: ba 87 b5 80 cs %r8,%r7,1408(%r11) Kernel image size change: add/remove: 756/750 grow/shrink: 646/3435 up/down: 30778/-46326 (-15548) Acked-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390/spinlock: Generate shorter code for arch_spin_unlock()

2024-11-28T13:12:04+00:00

Use mvhhi instead of sth to write a zero to spinlocks. Compared to the sth variant this avoids the load of zero to a register, and reduces register pressure. Signed-off-by: Heiko Carstens

s390/spinlock: Remove condition code clobber from arch_spin_unlock()

2024-11-28T13:12:04+00:00

Both instructions in arch_spin_unlock() do not clobber the condition code. Therefore remove the condition code clobber from the inline assembly. Signed-off-by: Heiko Carstens

s390/spinlock: Use symbolic names in inline assemblies

2024-11-28T13:12:04+00:00

Improve readability and use symbolic names. Signed-off-by: Heiko Carstens

s390/locking: Use arch_try_cmpxchg() instead of __atomic_cmpxchg_bool()

2024-11-12T13:01:29+00:00

Use arch_try_cmpxchg() instead of __atomic_cmpxchg_bool() everywhere. This generates the same code like before, but uses the standard cmpxchg() implementation instead of a custom __atomic_cmpxchg_bool(). Reviewed-by: Juergen Christ Signed-off-by: Heiko Carstens

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: 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/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: add KCSAN instrumentation to barriers and spinlocks

2022-04-25T11:54:16+00:00

test_barrier fails on s390 because of the missing KCSAN instrumentation for several synchronization primitives. Add it to barriers by defining __mb(), __rmb(), __wmb(), __dma_rmb() and __dma_wmb(), and letting the common code in asm-generic/barrier.h do the rest. Spinlocks require instrumentation only on the unlock path; notify KCSAN that the CPU cannot move memory accesses outside of the spin lock. In reality it also cannot move stores inside of it, but this is not important and can be omitted. Reported-by: Tobias Huschle Signed-off-by: Ilya Leoshkevich Signed-off-by: Heiko Carstens