Re: [PATCH v4 0/8] Generic IRQ entry/exit support for powerpc

[Shrikanth Hegde <sshegde@linux.ibm.com>]

Hi Mukesh.

On 1/23/26 1:09 PM, Mukesh Kumar Chaurasiya wrote:
> Adding support for the generic irq entry/exit handling for PowerPC. The
> goal is to bring PowerPC in line with other architectures that already
> use the common irq entry infrastructure, reducing duplicated code and
> making it easier to share future changes in entry/exit paths.
> 
> This is slightly tested of ppc64le and ppc32.
> 
> The performance benchmarks are below:
> 
> perf bench syscall usec/op (-ve is improvement)
> 
> | Syscall | Base        | test        | change % |
> | ------- | ----------- | ----------- | -------- |
> | basic   | 0.093543    | 0.093023    | -0.56    |
> | execve  | 446.557781  | 450.107172  | +0.79    |
> | fork    | 1142.204391 | 1156.377214 | +1.24    |
> | getpgid | 0.097666    | 0.092677    | -5.11    |
> 
> perf bench syscall ops/sec (+ve is improvement)
> 
> | Syscall | Base     | New      | change % |
> | ------- | -------- | -------- | -------- |
> | basic   | 10690548 | 10750140 | +0.56    |
> | execve  | 2239     | 2221     | -0.80    |
> | fork    | 875      | 864      | -1.26    |
> | getpgid | 10239026 | 10790324 | +5.38    |
> 
> 
> IPI latency benchmark (-ve is improvement)
> 
> | Metric         | Base (ns)     | New (ns)      | % Change |
> | -------------- | ------------- | ------------- | -------- |
> | Dry run        | 583136.56     | 584136.35     | 0.17%    |
> | Self IPI       | 4167393.42    | 4149093.90    | -0.44%   |
> | Normal IPI     | 61769347.82   | 61753728.39   | -0.03%   |
> | Broadcast IPI  | 2235584825.02 | 2227521401.45 | -0.36%   |
> | Broadcast lock | 2164964433.31 | 2125658641.76 | -1.82%   |
> 
> 
> Thats very close to performance earlier with arch specific handling.
> 
> Tests done:
>   - Build and boot on ppc64le pseries.
>   - Build and boot on ppc64le powernv8 powernv9 powernv10.
>   - Build and boot on ppc32.
>   - Performance benchmark done with perf syscall basic on pseries.
> 
> Changelog:
> V3 -> V4
>   - Fixed the issue in older gcc version where linker couldn't find
>     mem functions
>   - Merged IRQ enable and syscall enable into a single patch
>   - Cleanup for unused functions done in separate patch.
>   - Some other cosmetic changes
> V3: https://lore.kernel.org/all/20251229045416.3193779-1-mkchauras@linux.ibm.com/
> 
> V2 -> V3
>   - #ifdef CONFIG_GENERIC_IRQ_ENTRY removed from unnecessary places
>   - Some functions made __always_inline
>   - pt_regs padding changed to match 16byte interrupt stack alignment
>   - And some cosmetic changes from reviews from earlier patch
> V2: https://lore.kernel.org/all/20251214130245.43664-1-mkchauras@linux.ibm.com/
> 
> V1 -> V2
>   - Fix an issue where context tracking was showing warnings for
>     incorrect context
> V1: https://lore.kernel.org/all/20251102115358.1744304-1-mkchauras@linux.ibm.com/
> 
> RFC -> PATCH V1
>   - Fix for ppc32 spitting out kuap lock warnings.
>   - ppc64le powernv8 crash fix.
>   - Review comments incorporated from previous RFC.
> RFC https://lore.kernel.org/all/20250908210235.137300-2-mchauras@linux.ibm.com/
> 
> Mukesh Kumar Chaurasiya (8):
>    powerpc: rename arch_irq_disabled_regs
>    powerpc: Prepare to build with generic entry/exit framework
>    powerpc: introduce arch_enter_from_user_mode
>    powerpc: Introduce syscall exit arch functions
>    powerpc: add exit_flags field in pt_regs
>    powerpc: Prepare for IRQ entry exit
>    powerpc: Enable GENERIC_ENTRY feature
>    powerpc: Remove unused functions
> 
>   arch/powerpc/Kconfig                    |   1 +
>   arch/powerpc/include/asm/entry-common.h | 533 ++++++++++++++++++++++++
>   arch/powerpc/include/asm/hw_irq.h       |   4 +-
>   arch/powerpc/include/asm/interrupt.h    | 386 +++--------------
>   arch/powerpc/include/asm/kasan.h        |  15 +-
>   arch/powerpc/include/asm/ptrace.h       |   6 +-
>   arch/powerpc/include/asm/signal.h       |   1 -
>   arch/powerpc/include/asm/stacktrace.h   |   6 +
>   arch/powerpc/include/asm/syscall.h      |   5 +
>   arch/powerpc/include/asm/thread_info.h  |   1 +
>   arch/powerpc/include/uapi/asm/ptrace.h  |  14 +-
>   arch/powerpc/kernel/interrupt.c         | 254 ++---------
>   arch/powerpc/kernel/ptrace/ptrace.c     | 142 +------
>   arch/powerpc/kernel/signal.c            |  25 +-
>   arch/powerpc/kernel/syscall.c           | 119 +-----
>   arch/powerpc/kernel/traps.c             |   2 +-
>   arch/powerpc/kernel/watchdog.c          |   2 +-
>   arch/powerpc/perf/core-book3s.c         |   2 +-
>   18 files changed, 690 insertions(+), 828 deletions(-)
>   create mode 100644 arch/powerpc/include/asm/entry-common.h
> 

Ran it a bit on powernv (power9) too. Not warnings and similar
micro benchmark numbers.

I think this is in better shape now. With that,

for the series.
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>