From: Kees Cook <keescook@chromium.org>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Florian Weimer <fweimer@redhat.com>,
linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
linux-api@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH v2] ELF: supply userspace with available page shifts (AT_PAGE_SHIFT_MASK)
Date: Fri, 8 Dec 2023 10:29:25 -0800 [thread overview]
Message-ID: <202312081027.BA44B7B3@keescook> (raw)
In-Reply-To: <4f5f29d4-9c50-453c-8ad3-03a92fed192e@p183>
On Thu, Dec 07, 2023 at 05:57:05PM +0300, Alexey Dobriyan wrote:
> On Wed, Dec 06, 2023 at 12:47:27PM -0800, Kees Cook wrote:
> > Can't we have a generic ARCH_AT_PAGE_SHIFT_MASK too? Something like:
> >
> > #ifndef ARCH_AT_PAGE_SHIFT_MASK
> > #define ARCH_AT_PAGE_SHIFT_MASK
> > NEW_AUX_ENT(AT_PAGE_SHIFT_MASK, 1 << PAGE_SHIFT)
> > #endif
> >
> > Or am I misunderstanding something here?
>
> 1) Arch maintainers can opt into this new way to report information at
> their own pace.
>
> 2) AT_PAGE_SHIFT_MASK is about _all_ pagesizes supported by CPU.
> Reporting just one is missing the point.
>
> I'll clarify comment: mmap() support require many things including
> tests for hugetlbfs being mounted, this is about CPU support.
I significantly prefer APIs not being arch-specific, so I'd prefer we
always include AT_PAGE_SHIFT_MASK. For an architecture that doesn't
define its own ARCH_AT_PAGE_SHIFT_MASK, it's not _inaccurate_ to report
1 << PAGE_SHIFT, but it might be incomplete.
--
Kees Cook
next prev parent reply other threads:[~2023-12-08 18:29 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-04 17:18 [PATCH] ELF: supply userspace with available page shifts (AT_PAGE_SHIFT_LIST) Alexey Dobriyan
2023-12-05 9:51 ` Florian Weimer
2023-12-05 14:26 ` Alexey Dobriyan
2023-12-05 16:01 ` [PATCH v2] ELF: supply userspace with available page shifts (AT_PAGE_SHIFT_MASK) Alexey Dobriyan
2023-12-06 20:47 ` Kees Cook
2023-12-06 21:05 ` Florian Weimer
2023-12-06 21:09 ` Kees Cook
2023-12-07 15:04 ` Alexey Dobriyan
2023-12-07 14:57 ` Alexey Dobriyan
2023-12-07 15:32 ` Florian Weimer
2023-12-08 18:29 ` Kees Cook [this message]
2023-12-08 18:35 ` Florian Weimer
2023-12-08 18:38 ` Kees Cook
2023-12-09 9:44 ` Alexey Dobriyan
2023-12-07 18:44 ` [PATCH v3] ELF: AT_PAGE_SHIFT_MASK -- supply userspace with available page shifts Alexey Dobriyan
2023-12-12 21:09 ` Kees Cook
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202312081027.BA44B7B3@keescook \
--to=keescook@chromium.org \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=fweimer@redhat.com \
--cc=linux-api@vger.kernel.org \
--cc=linux-arch@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.