Re: [PATCH v17 15/15] arm64: vdso: Expose sigreturn address on vdso to the kernel

在 2026/7/23 2:18, Mark Rutland 写道:

On Tue, Jul 21, 2026 at 10:55:03AM +0200, Linus Walleij wrote:

quoted

On Tue, Jul 21, 2026 at 10:19 AM Jinjie Ruan [off-list ref] wrote:

quoted

Syscall User Dispatch (SUD) must not intercept the signal trampoline
code, otherwise returning from a signal with a locked selector may
cause infinite recursion into the signal handler.

Provide an arm64 implementation of arch_syscall_is_vdso_sigreturn()
to exclude these sigreturn syscalls from dispatch.

For native 64-bit tasks, check whether the current PC matches the 'svc #0'
instruction inside the vDSO sigreturn trampoline (defined in
arch/arm64/kernel/vdso/sigreturn.S as below).

        SYM_CODE_START(__kernel_rt_sigreturn)
                mov     x8, #__NR_rt_sigreturn
                svc     #0
        SYM_CODE_END(__kernel_rt_sigreturn)

For COMPAT tasks, verify that the instruction falls within the dedicated
'sigpage' range, since compat signal handlers use this architecture-
specific page (not the vDSO) for their return trampoline. This prevents
SUD from incorrectly dispatching syscalls issued during signal return.

Suggested-by: Thomas Weißschuh <redacted>
Suggested-by: Kevin Brodsky <redacted>
Suggested-by: kemal <redacted>
Signed-off-by: Jinjie Ruan <redacted>

I'm a bit scared about SUD.

Certainly we can merge patches 1-14 first and iron out
any trouble related to that and split this off so a separate
series to be applied lated?

I had already asked Jinie to drop SUD back in v14, and he had agreed:

  https://lore.kernel.org/lkml/akegeU59jSK9t7FX@J2N7QTR9R3/ (local)
  https://lore.kernel.org/lkml/3ac6d4be-7c57-44c2-80a0-408e2c6f8136@huawei.com/ (local)

Jinjie, please drop this for now, as we had _already_ agreed.

Ah, sorry about that.I will drop this SUD patch in the next revision.

I will look over the rest of the series soon.

Thank you! I look forward to your review and feedback on the rest of the
patches.

Thanks,
Jinjie

Mark.