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

[Jinjie Ruan <ruanjinjie@huawei.com>]

在 2026/7/23 2:18, Mark Rutland 写道:
> On Tue, Jul 21, 2026 at 10:55:03AM +0200, Linus Walleij wrote:
>> On Tue, Jul 21, 2026 at 10:19 AM Jinjie Ruan <ruanjinjie@huawei.com> wrote:
>>
>>> 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 <thomas.weissschuh@linutronix.de>
>>> Suggested-by: Kevin Brodsky <kevin.brodsky@arm.com>
>>> Suggested-by: kemal <kmal@cock.li>
>>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>>
>> 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/
>   https://lore.kernel.org/lkml/3ac6d4be-7c57-44c2-80a0-408e2c6f8136@huawei.com/
> 
> 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.
>