With this patch set, build fails.

Failure logs:

ld: warning: discarding dynamic section .glink
ld: warning: discarding dynamic section .plt
ld: linkage table error against `memset'
ld: stubs don't match calculated size
ld: can not build stubs: bad value
ld: init/main.o: in function `do_one_initcall':
/root/linux/init/main.c:1384: undefined reference to `memcpy'
ld: arch/powerpc/kernel/process.o: in function `arch_dup_task_struct':
/root/linux/arch/powerpc/kernel/process.c:1724: undefined reference to `memcpy'
ld: arch/powerpc/kernel/process.o: in function `copy_thread':
/root/linux/arch/powerpc/kernel/process.c:1812: undefined reference to `memcpy'
ld: arch/powerpc/kernel/signal.o: in function `do_signal':
/root/linux/arch/powerpc/kernel/signal.c:247: undefined reference to `memset'
ld: arch/powerpc/kernel/sysfs.o: in function `show_smt_snooze_delay':
/root/linux/arch/powerpc/kernel/sysfs.c:66: undefined reference to `memcpy'
ld: /root/linux/arch/powerpc/kernel/sysfs.c:66: undefined reference to `memcpy'
ld: arch/powerpc/kernel/time.o: in function `register_decrementer_clockevent':
/root/linux/arch/powerpc/kernel/time.c:834: undefined reference to `memcpy'
ld: arch/powerpc/kernel/time.o: in function `platform_device_register_resndata':
/root/linux/./include/linux/platform_device.h:160: undefined reference to `memset'
ld: arch/powerpc/kernel/ptrace/ptrace-noadv.o: in function `ptrace_set_debugreg':
/root/linux/arch/powerpc/kernel/ptrace/ptrace-noadv.c:130: undefined reference to `memcpy'
ld: arch/powerpc/kernel/paca.o: in function `init_lppaca':
/root/linux/arch/powerpc/kernel/paca.c:112: undefined reference to `memset'
ld: arch/powerpc/kernel/hw_breakpoint.o: in function `ptrace_triggered':
/root/linux/arch/powerpc/kernel/hw_breakpoint.c:607: undefined reference to `memcpy'
ld: arch/powerpc/kernel/mce.o: in function `get_mce_event':
/root/linux/arch/powerpc/kernel/mce.c:206: undefined reference to `memcpy'
ld: /root/linux/arch/powerpc/kernel/mce.c:206: undefined reference to `memcpy'
ld: arch/powerpc/kernel/mce_power.o: in function `mce_find_instr_ea_and_phys':
/root/linux/arch/powerpc/kernel/mce_power.c:461: undefined reference to `memcpy'
ld: arch/powerpc/kernel/security.o: in function `cpu_show_meltdown':
/root/linux/arch/powerpc/kernel/security.c:172: undefined reference to `memcpy'
ld: arch/powerpc/kernel/security.o:/root/linux/arch/powerpc/kernel/security.c:166: more undefined references to `memcpy' follow
ld: arch/powerpc/mm/mem.o: in function `execmem_arch_setup':
/root/linux/arch/powerpc/mm/mem.c:423: undefined reference to `memset'
ld: arch/powerpc/mm/book3s64/subpage_prot.o: in function `subpage_mark_vma_nohuge':
/root/linux/arch/powerpc/mm/book3s64/subpage_prot.c:155: undefined reference to `memset'
ld: arch/powerpc/mm/numa.o: in function `vphn_get_nid':
/root/linux/arch/powerpc/mm/numa.c:676: undefined reference to `memset'
ld: arch/powerpc/mm/numa.o: in function `find_and_update_cpu_nid':
/root/linux/arch/powerpc/mm/numa.c:1416: undefined reference to `memset'
ld: arch/powerpc/mm/numa.o: in function `cpu_to_coregroup_id':
/root/linux/arch/powerpc/mm/numa.c:1438: undefined reference to `memset'
ld: arch/powerpc/mm/ptdump/ptdump.o:/root/linux/arch/powerpc/mm/ptdump/ptdump.c:370: more undefined references to `memset' follow
ld: arch/powerpc/lib/mem_64.o: in function `__memmove':
/root/linux/arch/powerpc/lib/mem_64.S:103: undefined reference to `memcpy'
/root/linux/arch/powerpc/lib/mem_64.S:103:(.text+0x10c): call to `memcpy' lacks nop, can't restore toc; (plt call stub)
ld: final link failed: bad value
make[2]: *** [scripts/Makefile.vmlinux:72: vmlinux.unstripped] Error 1
make[1]: *** [/root/linux/Makefile:1276: vmlinux] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [Makefile:248: __sub-make] Error 2

Regards,
Venkat.

On 29 Dec 2025, at 10:24 AM, Mukesh Kumar Chaurasiya [off-list ref] 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

| Syscall | Base       | New        | change % |
| ------- | ---------- | ---------- | -------- |
| basic   | 0.173212   | 0.133294   | -23.05   |
| execve  | 363.176190 | 357.148150 | -1.66    |
| fork    | 853.657880 | 840.268800 | -1.57    |
| getpgid | 0.174832   | 0.135372   | -22.57   |

perf bench syscall ops/sec

| Syscall | Base    | New     | change % |
| ------- | ------- | ------- | -------- |
| basic   | 6006021 | 7502236 | +24.91   |
| execve  | 2753    | 2800    | +1.71    |
| fork    | 1171    | 1190    | +1.62    |
| getpgid | 5942117 | 7387040 | +24.32   |

IPI latency benchmark

| Metric         | Base (ns)     | Test (ns)     | change % |
| -------------- | ------------- | ------------- | -------- |
| Dry-run        | 206652.45     | 209317.37     | +1.29    |
| Self-IPI       | 3567895.23    | 3590444.77    | +0.63    |
| Normal IPI     | 148570416.17  | 148564173.40  | -0.00    |
| Broadcast IPI  | 4033489673.38 | 4007319512.62 | -0.65    |
| Broadcast lock | 4011023005.48 | 4010267885.93 | -0.02    |


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:

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/ (local)

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/ (local)

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/ (local)

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 IRQ generic entry/exit path.
 powerpc: Enable Generic Entry/Exit for syscalls.

arch/powerpc/Kconfig                    |   2 +
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/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         | 255 ++----------
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 +-
17 files changed, 681 insertions(+), 824 deletions(-)
create mode 100644 arch/powerpc/include/asm/entry-common.h

-- 
2.52.0