linux-kernel - Re: [RFC PATCH 1/2] arm64: run softirqs on the per-CPU IRQ stack

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: Windows password security audit tool. GUI, reports in PDF.

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

Date:   Thu, 7 Jul 2022 14:58:21 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Qi Zheng <zhengqi.arch@...edance.com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [RFC PATCH 1/2] arm64: run softirqs on the per-CPU IRQ stack

On Thu, Jul 7, 2022 at 1:05 PM Qi Zheng <zhengqi.arch@...edance.com> wrote:
>
> Currently arm64 supports per-CPU IRQ stack, but softirqs
> are still handled in the task context.
>
> Since any call to local_bh_enable() at any level in the task's
> call stack may trigger a softirq processing run, which could
> potentially cause a task stack overflow if the combined stack
> footprints exceed the stack's size, let's run these softirqs
> on the IRQ stack as well.
>
> Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>

I think this is the correct approach, but your patch conflicts with another
patch I have queued up in the asm-generic tree, see
https://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic.git/commit/?h=asm-generic&id=f2c5092190f21

Please adapt accordingly.

Are there any architectures left that use IRQ stacks but don't
set HAVE_SOFTIRQ_ON_OWN_STACK? If not, we could
also consider removing the Kconfig symbol and just requiring
it to be done this way (for non-PREEMPT_RT).

        Arnd