linux-kernel - Re: [PATCHSET RFC v3 0/6] Add support for TIF_NOTIFY

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sat, 10 Oct 2020 10:53:44 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     Miroslav Benes <mbenes@...e.cz>, Oleg Nesterov <oleg@...hat.com>
Cc:     linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
        peterz@...radead.org, tglx@...utronix.de,
        live-patching@...r.kernel.org
Subject: Re: [PATCHSET RFC v3 0/6] Add support for TIF_NOTIFY_SIGNAL

On 10/9/20 9:21 AM, Jens Axboe wrote:
> On 10/9/20 2:01 AM, Miroslav Benes wrote:
>> On Thu, 8 Oct 2020, Oleg Nesterov wrote:
>>
>>> On 10/05, Jens Axboe wrote:
>>>>
>>>> Hi,
>>>>
>>>> The goal is this patch series is to decouple TWA_SIGNAL based task_work
>>>> from real signals and signal delivery.
>>>
>>> I think TIF_NOTIFY_SIGNAL can have more users. Say, we can move
>>> try_to_freeze() from get_signal() to tracehook_notify_signal(), kill
>>> fake_signal_wake_up(), and remove freezing() from recalc_sigpending().
>>>
>>> Probably the same for TIF_PATCH_PENDING, klp_send_signals() can use
>>> set_notify_signal() rather than signal_wake_up().
>>
>> Yes, that was my impression from the patch set too, when I accidentally 
>> noticed it.
>>
>> Jens, could you CC our live patching ML when you submit v4, please? It 
>> would be a nice cleanup.
> 
> Definitely, though it'd be v5 at this point. But we really need to get
> all archs supporting TIF_NOTIFY_SIGNAL first. Once we have that, there's
> a whole slew of cleanups that'll fall out naturally:
> 
> - Removal of JOBCTL_TASK_WORK
> - Removal of special path for TWA_SIGNAL in task_work
> - TIF_PATCH_PENDING can be converted and then removed
> - try_to_freeze() cleanup that Oleg mentioned
> 
> And probably more I'm not thinking of right now :-)

Here's the current series, I took a stab at converting all archs to
support TIF_NOTIFY_SIGNAL so we have a base to build on top of. Most
of them were straight forward, but I need someone to fixup powerpc,
verify arm and s390.

But it's a decent start I think, and means that we can drop various
bits as is done at the end of the series. I could swap things around
a bit and avoid having the intermediate step, but I envision that
getting this in all archs will take a bit longer than just signing off
on the generic/x86 bits. So probably best to keep the series as it is
for now, and work on getting the arch bits verified/fixed/tested.

https://git.kernel.dk/cgit/linux-block/log/?h=tif-task_work

-- 
Jens Axboe