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

[Mark Rutland <mark.rutland@arm.com>]

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.

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@huawei.com/
> > 
> > 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@huawei.com/
> > 
> > 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@huawei.com/
> > 
> > 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@huawei.com/
> > 
> > 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@huawei.com/
> > 
> > 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@huawei.com/
> > 
> > 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@huawei.com/
> > 
> > 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@huawei.com/
> > 
> > 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(-)
> >