[PATCH v5 0/8] Generic IRQ entry/exit support for powerpc

Mukesh Kumar Chaurasiya (IBM)
2026-04-27T12:28:02Z

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:
V4 -> V5:
- Rebased on latest mainline
V4: https://lore.kernel.org/all/20260123073916.956498-1-mkchauras@linux.ibm.com/

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

--
2.53.0