Re: [PATCH -next v7 0/7] arm64: entry: Convert to generic irq entry

[Mark Rutland <mark.rutland@xxxxxxx>]

Hi,

This is looking pretty good now, thanks for continuing to work on this!

I've left a couple of minor comments, and Ada has left a few more. If
you're able to address those and respin atop v6.17-rc1, I think we can
start figuring out how to queue this.

Mark.

On Tue, Jul 29, 2025 at 09:54:49AM +0800, Jinjie Ruan wrote:
> Currently, x86, Riscv, Loongarch use the generic entry. Also convert
> arm64 to use the generic entry infrastructure from kernel/entry/*.
> The generic entry makes maintainers' work easier and codes more elegant,
> which will make PREEMPT_DYNAMIC and PREEMPT_LAZY use the generic entry
> common code and remove a lot of duplicate code.
> 
> Since commit a70e9f647f50 ("entry: Split generic entry into generic
> exception and syscall entry") split the generic entry into generic irq
> entry and generic syscall entry, it is time to convert arm64 to use
> the generic irq entry. And ARM64 will be completely converted to generic
> entry in the upcoming patch series.
> 
> The main convert steps are as follows:
> - Split generic entry into generic irq entry and generic syscall to
>   make the single patch more concentrated in switching to one thing.
> - Make arm64 easier to use irqentry_enter/exit().
> - Make arm64 closer to the PREEMPT_DYNAMIC code of generic entry.
> - Switch to generic irq entry.
> 
> It was tested ok with following test cases on QEMU virt platform:
>  - Perf tests.
>  - Different `dynamic preempt` mode switch.
>  - Pseudo NMI tests.
>  - Stress-ng CPU stress test.
>  - MTE test case in Documentation/arch/arm64/memory-tagging-extension.rst
>    and all test cases in tools/testing/selftests/arm64/mte/*.
> 
> The test QEMU configuration is as follows:
> 
>       qemu-system-aarch64 \
>               -M virt,gic-version=3,virtualization=on,mte=on \
>               -cpu max,pauth-impdef=on \
>               -kernel Image \
>               -smp 8,sockets=1,cores=4,threads=2 \
>               -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" \
>               -drive if=none,file=images/rootfs.ext4,format=raw,id=hd0 \
>               -device virtio-blk-device,drive=hd0 \
> 
> Changes in v7:
> - Rebased on v6.16-rc7 and remove the merged first patch.
> - Update the commit message.
> 
> Changes in v6:
> - Rebased on 6.14 rc2 next.
> - Put the syscall bits aside and split it out.
> - Have the split patch before the arm64 changes.
> - Merge some tightly coupled patches.
> - Adjust the order of some patches to make them more reasonable.
> - Define regs_irqs_disabled() by inline function.
> - Define interrupts_enabled() in terms of regs_irqs_disabled().
> - Delete the fast_interrupts_enabled() macro.
> - irqentry_state_t -> arm64_irqentry_state_t.
> - Remove arch_exit_to_user_mode_prepare() and pull local_daif_mask() later
>   in the arm64 exit sequence
> - Update the commit message.
> 
> Changes in v5:
> - Not change arm32 and keep inerrupts_enabled() macro for gicv3 driver.
> - Move irqentry_state definition into arch/arm64/kernel/entry-common.c.
> - Avoid removing the __enter_from_*() and __exit_to_*() wrappers.
> - Update "irqentry_state_t ret/irq_state" to "state"
>   to keep it consistently.
> - Use generic irq entry header for PREEMPT_DYNAMIC after split
>   the generic entry.
> - Also refactor the ARM64 syscall code.
> - Introduce arch_ptrace_report_syscall_entry/exit(), instead of
>   arch_pre/post_report_syscall_entry/exit() to simplify code.
> - Make the syscall patches clear separation.
> - Update the commit message.
> 
> Changes in v4:
> - Rework/cleanup split into a few patches as Mark suggested.
> - Replace interrupts_enabled() macro with regs_irqs_disabled(), instead
>   of left it here.
> - Remove rcu and lockdep state in pt_regs by using temporary
>   irqentry_state_t as Mark suggested.
> - Remove some unnecessary intermediate functions to make it clear.
> - Rework preempt irq and PREEMPT_DYNAMIC code
>   to make the switch more clear.
> - arch_prepare_*_entry/exit() -> arch_pre_*_entry/exit().
> - Expand the arch functions comment.
> - Make arch functions closer to its caller.
> - Declare saved_reg in for block.
> - Remove arch_exit_to_kernel_mode_prepare(), arch_enter_from_kernel_mode().
> - Adjust "Add few arch functions to use generic entry" patch to be
>   the penultimate.
> - Update the commit message.
> - Add suggested-by.
> 
> Changes in v3:
> - Test the MTE test cases.
> - Handle forget_syscall() in arch_post_report_syscall_entry()
> - Make the arch funcs not use __weak as Thomas suggested, so move
>   the arch funcs to entry-common.h, and make arch_forget_syscall() folded
>   in arch_post_report_syscall_entry() as suggested.
> - Move report_single_step() to thread_info.h for arm64
> - Change __always_inline() to inline, add inline for the other arch funcs.
> - Remove unused signal.h for entry-common.h.
> - Add Suggested-by.
> - Update the commit message.
> 
> Changes in v2:
> - Add tested-by.
> - Fix a bug that not call arch_post_report_syscall_entry() in
>   syscall_trace_enter() if ptrace_report_syscall_entry() return not zero.
> - Refactor report_syscall().
> - Add comment for arch_prepare_report_syscall_exit().
> - Adjust entry-common.h header file inclusion to alphabetical order.
> - Update the commit message.
> 
> Jinjie Ruan (7):
>   arm64: ptrace: Replace interrupts_enabled() with regs_irqs_disabled()
>   arm64: entry: Refactor the entry and exit for exceptions from EL1
>   arm64: entry: Rework arm64_preempt_schedule_irq()
>   arm64: entry: Use preempt_count() and need_resched() helper
>   arm64: entry: Refactor preempt_schedule_irq() check code
>   arm64: entry: Move arm64_preempt_schedule_irq() into
>     __exit_to_kernel_mode()
>   arm64: entry: Switch to generic IRQ entry
> 
>  arch/arm64/Kconfig                    |   1 +
>  arch/arm64/include/asm/daifflags.h    |   2 +-
>  arch/arm64/include/asm/entry-common.h |  56 ++++
>  arch/arm64/include/asm/preempt.h      |   2 -
>  arch/arm64/include/asm/ptrace.h       |  13 +-
>  arch/arm64/include/asm/xen/events.h   |   2 +-
>  arch/arm64/kernel/acpi.c              |   2 +-
>  arch/arm64/kernel/debug-monitors.c    |   2 +-
>  arch/arm64/kernel/entry-common.c      | 411 +++++++++-----------------
>  arch/arm64/kernel/sdei.c              |   2 +-
>  arch/arm64/kernel/signal.c            |   3 +-
>  kernel/entry/common.c                 |  16 +-
>  12 files changed, 217 insertions(+), 295 deletions(-)
>  create mode 100644 arch/arm64/include/asm/entry-common.h
> 
> -- 
> 2.34.1
>