[PATCH v2 00/12] s390: More this_cpu_*() changes

[Heiko Carstens]

v2:
- Yet another brown paper bug: Re-add CPU migration check to last
  patch. Unconditionally recalculating and updating the percpu variable
  address and percpu offset register can corrupt previous context
  register state in several cases (not only the single case reported by
  Sashiko).

v1:
Most of this is only about cleaning up the percpu code after preemptible
this_cpu_*() operations have been implemented. The first ten patches are
all more or less trivial cleanup patches trying to make the code shorter
and more readable.

The only non-trivial patch is the last one, which converts s390's
this_cpu_*() operations to use a similar scheme like Mark Rutland
provided it for arm64 [1]. This allows to simplify the irq entry and exit
path, however at the cost of slightly worse code for this_cpu_*()
operations.

The simplified irq entry and exit code seems to be worth it. Usable
performance numbers are not available yet, however I don't expect big
difference to before.

[1] https://lore.kernel.org/all/20260904161758.376504-1-mark.rutland@xxxxxxx/

Thanks,
Heiko

Heiko Carstens (12):
  s390/percpu: Fix comment typo
  s390/percpu: Add sanity check to GEN_MVIY macro
  s390/lowcore: Remove _AC() from LOWCORE_ALT_ADDRESS
  s390/percpu: Let MVIY_PERCPU() calculate alternative displacement
  s390/percpu/lowcore: Add and use LC_PERCPU lowcore offset defines
  s390/percpu: Rename inline assembly symbolic names
  s390/percpu: Use __PCPU_BEGIN() and __PCPU_END() for inline assemblies
  s390/percpu: Use percpu code section for this_cpu_cmpxchg128()
  s390/percpu: Use percpu code section for this_cpu_xchg()
  s390/percpu: Use percpu code section for this_cpu_cmpxchg()
  s390: Add CC_HAS_ASM_M_FORMAT_FLAG config option
  s390/percpu: Rework to simplify percpu_entry() and percpu_exit()

 arch/s390/Kconfig                    |   6 +
 arch/s390/include/asm/entry-percpu.h |  71 ++---
 arch/s390/include/asm/lowcore.h      |   5 +-
 arch/s390/include/asm/percpu.h       | 381 +++++++++++++++++----------
 arch/s390/include/asm/ptrace.h       |   2 +-
 arch/s390/kernel/irq.c               |  10 +-
 arch/s390/kernel/nmi.c               |   4 +-
 arch/s390/kernel/traps.c             |   4 +-
 8 files changed, 280 insertions(+), 203 deletions(-)

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2.53.0