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From: Marco Elver <elver@google.com>
To: Sven Schnelle <svens@linux.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] kfence: only handle kernel mode faults
Date: Fri, 14 May 2021 12:52:38 +0200	[thread overview]
Message-ID: <CANpmjNOLSuqeTr8YOnvz-V=eudBwraNvm+9V+YxEBUCm=EFwxw@mail.gmail.com> (raw)
In-Reply-To: <20210514092139.3225509-3-svens@linux.ibm.com>

On Fri, 14 May 2021 at 11:22, Sven Schnelle <svens@linux.ibm.com> wrote:
>
> Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
> ---
>  mm/kfence/core.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/mm/kfence/core.c b/mm/kfence/core.c
> index bc15e3cb71d5..161df492750c 100644
> --- a/mm/kfence/core.c
> +++ b/mm/kfence/core.c
> @@ -813,6 +813,9 @@ bool kfence_handle_page_fault(unsigned long addr, bool is_write, struct pt_regs
>         enum kfence_error_type error_type;
>         unsigned long flags;
>
> +       if (user_mode(regs))
> +               return false;
> +

I don't think it's required on all architectures, correct? If so, I
think this should be part of the arch-specific code, i.e. just do "if
(user_mode(regs) && kfence_handle_page_fault(...))" or similar.
Because otherwise we'll wonder in future why we ever needed this, and
e.g. determine it's useless and remove it again. ;-) Either that, or a
comment. But I'd prefer to just keep it in the arch-specific code if
required, because it seems to be the exception rather than the norm.

Thanks,
-- Marco

  reply	other threads:[~2021-05-14 10:52 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-14  9:21 [RFC] minor kfence patches Sven Schnelle
2021-05-14  9:21 ` [PATCH 1/2] kfence: add function to mask address bits Sven Schnelle
2021-05-14 10:54   ` Marco Elver
2021-05-14 11:03     ` Sven Schnelle
2021-05-14 11:23       ` Marco Elver
2021-05-14  9:21 ` [PATCH 2/2] kfence: only handle kernel mode faults Sven Schnelle
2021-05-14 10:52   ` Marco Elver [this message]
2021-05-14 10:55     ` Sven Schnelle
2021-05-14 10:59       ` Marco Elver
2021-05-14 10:56 ` [RFC] minor kfence patches Marco Elver

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