[RFC PATCH 0/9] powerpc/64s: fast interrupt exit

[Nicholas Piggin]

This series attempts to improve the speed of interrupts and system calls
in two major ways.

Firstly, the SRR/HSRR registers do not need to be reloaded if they were
not used or clobbered fur the duration of the interrupt.

Secondly, an alternate return location facility is added for soft-masked
asynchronous interrupts and then that's used to set everything up for
return without having to disable MSR RI or EE.

After this series, the entire system call / interrupt handler fast path
executes no mtsprs and one mtmsrd to enable interrupts initially, and
the system call vectored path doesn't even need to do that.

Thanks,
Nick

Nicholas Piggin (9):
  powerpc/64s: syscall real mode entry use mtmsrd rather than rfid
  powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE]
  powerpc/64s: introduce different functions to return from SRR vs HSRR
    interrupts
  powerpc/64s: avoid reloading (H)SRR registers if they are still valid
  powerpc/64: move interrupt return asm to interrupt_64.S
  powerpc/64s: save one more register in the masked interrupt handler
  powerpc/64s: allow alternate return locations for soft-masked
    interrupts
  powerpc/64s: interrupt soft-enable race fix
  powerpc/64s: use interrupt restart table to speed up return from
    interrupt

 arch/powerpc/Kconfig.debug                 |   5 +
 arch/powerpc/include/asm/asm-prototypes.h  |   4 +-
 arch/powerpc/include/asm/head-64.h         |   2 +-
 arch/powerpc/include/asm/interrupt.h       |  18 +
 arch/powerpc/include/asm/paca.h            |   3 +
 arch/powerpc/include/asm/ppc_asm.h         |   8 +
 arch/powerpc/include/asm/ptrace.h          |  28 +-
 arch/powerpc/kernel/asm-offsets.c          |   5 +
 arch/powerpc/kernel/entry_64.S             | 508 ---------------
 arch/powerpc/kernel/exceptions-64s.S       | 180 ++++--
 arch/powerpc/kernel/fpu.S                  |   2 +
 arch/powerpc/kernel/head_64.S              |   5 +-
 arch/powerpc/kernel/interrupt_64.S         | 720 +++++++++++++++++++++
 arch/powerpc/kernel/irq.c                  |  79 ++-
 arch/powerpc/kernel/kgdb.c                 |   2 +-
 arch/powerpc/kernel/kprobes-ftrace.c       |   2 +-
 arch/powerpc/kernel/kprobes.c              |  10 +-
 arch/powerpc/kernel/process.c              |  21 +-
 arch/powerpc/kernel/rtas.c                 |  13 +-
 arch/powerpc/kernel/signal.c               |   2 +-
 arch/powerpc/kernel/signal_64.c            |  14 +
 arch/powerpc/kernel/syscall_64.c           | 242 ++++---
 arch/powerpc/kernel/syscalls.c             |   2 +
 arch/powerpc/kernel/traps.c                |  18 +-
 arch/powerpc/kernel/vector.S               |   6 +-
 arch/powerpc/kernel/vmlinux.lds.S          |  10 +
 arch/powerpc/lib/Makefile                  |   2 +-
 arch/powerpc/lib/restart_table.c           |  26 +
 arch/powerpc/lib/sstep.c                   |   5 +-
 arch/powerpc/math-emu/math.c               |   2 +-
 arch/powerpc/mm/fault.c                    |   2 +-
 arch/powerpc/perf/core-book3s.c            |  19 +-
 arch/powerpc/platforms/powernv/opal-call.c |   3 +
 arch/powerpc/sysdev/fsl_pci.c              |   2 +-
 34 files changed, 1244 insertions(+), 726 deletions(-)
 create mode 100644 arch/powerpc/kernel/interrupt_64.S
 create mode 100644 arch/powerpc/lib/restart_table.c

-- 
2.23.0