Re: [PATCH v14 00/10] arm64: entry: Convert to Generic Entry

[Jinjie Ruan]

On 2026/4/9 15:36, Mark Rutland wrote:
> Hi Jinjie,
> 
> On Thu, Apr 09, 2026 at 02:29:04PM +0800, Jinjie Ruan wrote:
>> On 2026/3/20 18:26, Jinjie Ruan wrote:
>>> Currently, x86, Riscv, Loongarch use the Generic Entry which makes
>>> maintainers' work easier and codes more elegant. arm64 has already
>>> successfully switched to the Generic IRQ Entry in commit
>>> b3cf07851b6c ("arm64: entry: Switch to generic IRQ entry"), it is
>>> time to completely convert arm64 to Generic Entry.
>>>
>>> The goal is to bring arm64 in line with other architectures that already
>>> use the generic entry infrastructure, reducing duplicated code and
>>> making it easier to share future changes in entry/exit paths, such as
>>> "Syscall User Dispatch" and RSEQ optimizations.
>>
>> Hi,
>>
>> Just a quick ping to see if this series is good to go. Do I need to
>> provide a new version rebased on the latest arm64 for-next/generic-entry
>> branches, or is the current version acceptable?
> 
> Sorry, this is on my list to review, but I've been busy fixing other
> issues (e.g. the preemption issues from moving to generic irqentry), and
> haven't yet had the time to go over this in detail.
> 
> This series might be fine as-is, but given that it's incredibly easy to
> introduce subtle and hard-to-fix regressions to user ABI, I don't think
> we can assume that it's safe until we've gone over it thoroughly.
> 
> For the moment, no need to resend. If you haven't received comments by
> v7.1-rc1, please rebase and resend then.

Hi Mark,

Thank you for the update. I completely understand the sensitivity of the
entry code and the need for a thorough review to avoid any ABI regressions.

I will wait for your feedback and will only rebase/resend if I haven't
heard back by v7.1-rc1, as suggested.

Best regards,
Jinjie

> 
> Thanks,
> Mark.
> 
>>> This patch set is rebased on arm64 for-next/core. This series contains
>>> foundational updates for arm64. As suggested by Linus Walleij, these 10
>>> patches are being submitted separately for inclusion in the arm64 tree.
>>>
>>> And the performance benchmarks results on qemu-kvm are below:
>>>
>>> perf bench syscall usec/op (-ve is improvement)
>>>
>>> | Syscall | Base        | Generic Entry | change % |
>>> | ------- | ----------- | ------------- | -------- |
>>> | basic   | 0.123997    | 0.120872      | -2.57    |
>>> | execve  | 512.1173    | 504.9966      | -1.52    |
>>> | fork    | 114.1144    | 113.2301      | -1.06    |
>>> | getpgid | 0.120182    | 0.121245      | +0.9     |
>>>
>>> perf bench syscall ops/sec (+ve is improvement)
>>>
>>> | Syscall | Base     | Generic Entry| change % |
>>> | ------- | -------- | ------------ | -------- |
>>> | basic   | 8064712  | 8273212      | +2.48    |
>>> | execve  | 1952     | 1980         | +1.52    |
>>> | fork    | 8763     | 8832         | +1.06    |
>>> | getpgid | 8320704  | 8247810      | -0.9     |
>>>
>>> Therefore, the syscall performance variation ranges from a 1% regression
>>> to a 2.5% improvement.
>>>
>>> It was tested ok with following test cases on QEMU virt platform:
>>>  - Stress-ng CPU stress test.
>>>  - Hackbench stress test.
>>>  - "sud" selftest testcase.
>>>  - get_set_sud, get_syscall_info, set_syscall_info, peeksiginfo
>>>    in tools/testing/selftests/ptrace.
>>>  - breakpoint_test_arm64 in selftests/breakpoints.
>>>  - syscall-abi and ptrace in tools/testing/selftests/arm64/abi
>>>  - fp-ptrace, sve-ptrace, za-ptrace in selftests/arm64/fp.
>>>  - vdso_test_getrandom in tools/testing/selftests/vDSO
>>>  - Strace tests.
>>>  - slice_test for rseq optimizations.
>>>
>>> The test QEMU configuration is as follows:
>>>
>>> 	qemu-system-aarch64 \
>>> 		-M virt \
>>> 		-enable-kvm \
>>> 		-cpu host \
>>> 		-kernel Image \
>>> 		-smp 8 \
>>> 		-m 512m \
>>> 		-nographic \
>>> 		-no-reboot \
>>> 		-device virtio-rng-pci \
>>> 		-append "root=/dev/vda rw console=ttyAMA0 kgdboc=ttyAMA0,115200 \
>>> 			earlycon preempt=voluntary irqchip.gicv3_pseudo_nmi=1 audit=1" \
>>> 		-drive if=none,file=images/rootfs.ext4,format=raw,id=hd0 \
>>> 		-device virtio-blk-device,drive=hd0 \
>>>
>>> Changes in v14:
>>> - Initialize ret = 0 in syscall_trace_enter().
>>> - Split into two patch sets as Linus Walleij suggested, so this patch set
>>>   can be applied separately to the arm64 tree.
>>> - Rebased on arm64 for-next/core branch.
>>> - Collect Reviewed-by and Acked-by.
>>> - Link to v13 resend: https://lore.kernel.org/all/20260317082020.737779-15-ruanjinjie@xxxxxxxxxx/
>>>
>>> Changes in v13 resend:
>>> - Fix exit_to_user_mode_prepare_legacy() issues.
>>> - Also move TIF_SINGLESTEP to generic TIF infrastructure for loongarch.
>>> - Use generic TIF bits for arm64 and moving TIF_SINGLESTEP to
>>>   generic TIF for related architectures separately.
>>> - Refactor syscall_trace_enter/exit() to accept flags and Use
>>>   syscall_get_nr() helper separately.
>>> - Tested with slice_test for rseq optimizations.
>>> - Add acked-by.
>>> - Link to v13: https://lore.kernel.org/all/20260313094738.3985794-1-ruanjinjie@xxxxxxxxxx/
>>>
>>> Changes in v13:
>>> - Rebased on v7.0-rc3, so drop the firt applied arm64 patch.
>>> - Use generic TIF bits to enables RSEQ optimization.
>>> - Update most of the commit message to make it more clear.
>>> - Link to v12: https://lore.kernel.org/all/20260203133728.848283-1-ruanjinjie@xxxxxxxxxx/
>>>
>>> Changes in v12:
>>> - Rebased on "sched/core", so remove the four generic entry patches.
>>> - Move "Expand secure_computing() in place" and
>>>   "Use syscall_get_arguments() helper" patch forward, which will group all
>>>   non-functional cleanups at the front.
>>> - Adjust the explanation for moving rseq_syscall() before
>>>   audit_syscall_exit().
>>> - Link to v11: https://lore.kernel.org/all/20260128031934.3906955-1-ruanjinjie@xxxxxxxxxx/
>>>
>>> Changes in v11:
>>> - Remove unused syscall in syscall_trace_enter().
>>> - Update and provide a detailed explanation of the differences after
>>>   moving rseq_syscall() before audit_syscall_exit().
>>> - Rebased on arm64 (for-next/entry), and remove the first applied 3 patchs.
>>> - syscall_exit_to_user_mode_work() for arch reuse instead of adding
>>>   new syscall_exit_to_user_mode_work_prepare() helper.
>>> - Link to v10: https://lore.kernel.org/all/20251222114737.1334364-1-ruanjinjie@xxxxxxxxxx/
>>>
>>> Changes in v10:
>>> - Rebased on v6.19-rc1, rename syscall_exit_to_user_mode_prepare() to
>>>   syscall_exit_to_user_mode_work_prepare() to avoid conflict.
>>> - Also inline syscall_trace_enter().
>>> - Support aarch64 for sud_benchmark.
>>> - Update and correct the commit message.
>>> - Add Reviewed-by.
>>> - Link to v9: https://lore.kernel.org/all/20251204082123.2792067-1-ruanjinjie@xxxxxxxxxx/
>>>
>>> Changes in v9:
>>> - Move "Return early for ptrace_report_syscall_entry() error" patch ahead
>>>   to make it not introduce a regression.
>>> - Not check _TIF_SECCOMP/SYSCALL_EMU for syscall_exit_work() in
>>>   a separate patch.
>>> - Do not report_syscall_exit() for PTRACE_SYSEMU_SINGLESTEP in a separate
>>>   patch.
>>> - Add two performance patch to improve the arm64 performance.
>>> - Add Reviewed-by.
>>> - Link to v8: https://lore.kernel.org/all/20251126071446.3234218-1-ruanjinjie@xxxxxxxxxx/
>>>
>>> Changes in v8:
>>> - Rename "report_syscall_enter()" to "report_syscall_entry()".
>>> - Add ptrace_save_reg() to avoid duplication.
>>> - Remove unused _TIF_WORK_MASK in a standalone patch.
>>> - Align syscall_trace_enter() return value with the generic version.
>>> - Use "scno" instead of regs->syscallno in el0_svc_common().
>>> - Move rseq_syscall() ahead in a standalone patch to clarify it clearly.
>>> - Rename "syscall_trace_exit()" to "syscall_exit_work()".
>>> - Keep the goto in el0_svc_common().
>>> - No argument was passed to __secure_computing() and check -1 not -1L.
>>> - Remove "Add has_syscall_work() helper" patch.
>>> - Move "Add syscall_exit_to_user_mode_prepare() helper" patch later.
>>> - Add miss header for asm/entry-common.h.
>>> - Update the implementation of arch_syscall_is_vdso_sigreturn().
>>> - Add "ARCH_SYSCALL_WORK_EXIT" to be defined as "SECCOMP | SYSCALL_EMU"
>>>   to keep the behaviour unchanged.
>>> - Add more testcases test.
>>> - Add Reviewed-by.
>>> - Update the commit message.
>>> - Link to v7: https://lore.kernel.org/all/20251117133048.53182-1-ruanjinjie@xxxxxxxxxx/
>>>
>>> Jinjie Ruan (10):
>>>   arm64/ptrace: Refactor syscall_trace_enter/exit() to accept flags
>>>     parameter
>>>   arm64/ptrace: Use syscall_get_nr() helper for syscall_trace_enter()
>>>   arm64/ptrace: Expand secure_computing() in place
>>>   arm64/ptrace: Use syscall_get_arguments() helper for audit
>>>   arm64: ptrace: Move rseq_syscall() before audit_syscall_exit()
>>>   arm64: syscall: Introduce syscall_exit_to_user_mode_work()
>>>   arm64/ptrace: Define and use _TIF_SYSCALL_EXIT_WORK
>>>   arm64/ptrace: Skip syscall exit reporting for PTRACE_SYSEMU_SINGLESTEP
>>>   arm64: entry: Convert to generic entry
>>>   arm64: Inline el0_svc_common()
>>>
>>>  arch/arm64/Kconfig                    |   2 +-
>>>  arch/arm64/include/asm/entry-common.h |  76 +++++++++++++++++
>>>  arch/arm64/include/asm/syscall.h      |  19 ++++-
>>>  arch/arm64/include/asm/thread_info.h  |  16 +---
>>>  arch/arm64/kernel/debug-monitors.c    |   7 ++
>>>  arch/arm64/kernel/entry-common.c      |  25 ++++--
>>>  arch/arm64/kernel/ptrace.c            | 115 --------------------------
>>>  arch/arm64/kernel/signal.c            |   2 +-
>>>  arch/arm64/kernel/syscall.c           |  29 ++-----
>>>  include/linux/irq-entry-common.h      |   8 --
>>>  include/linux/rseq_entry.h            |  18 ----
>>>  11 files changed, 130 insertions(+), 187 deletions(-)
>>>
>