From: Ard Biesheuvel <ardb@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>,
kernel-hardening@lists.openwall.com,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [RFC PATCH] arm64: remove CONFIG_DEBUG_ALIGN_RODATA feature
Date: Thu, 2 Apr 2020 13:24:09 +0200 [thread overview]
Message-ID: <CAMj1kXFTnqZHWZX5yhkG4+pd04JzGriFW6gjBrAnQ-LQQmEi3Q@mail.gmail.com> (raw)
In-Reply-To: <20200402111502.GC21087@mbp>
On Thu, 2 Apr 2020 at 13:15, Catalin Marinas <catalin.marinas@arm.com> wrote:
>
> On Sun, Mar 29, 2020 at 04:12:58PM +0200, Ard Biesheuvel wrote:
> > When CONFIG_DEBUG_ALIGN_RODATA is enabled, kernel segments mapped with
> > different permissions (r-x for .text, r-- for .rodata, rw- for .data,
> > etc) are rounded up to 2 MiB so they can be mapped more efficiently.
> > In particular, it permits the segments to be mapped using level 2
> > block entries when using 4k pages, which is expected to result in less
> > TLB pressure.
> >
> > However, the mappings for the bulk of the kernel will use level 2
> > entries anyway, and the misaligned fringes are organized such that they
> > can take advantage of the contiguous bit, and use far fewer level 3
> > entries than would be needed otherwise.
> >
> > This makes the value of this feature dubious at best, and since it is not
> > enabled in defconfig or in the distro configs, it does not appear to be
> > in wide use either. So let's just remove it.
> >
> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
>
> Happy to take this patch via the arm64 tree for 5.7 (no new
> functionality), unless you want it to go with your other relocation
> login in the EFI stub patches.
>
If you don't mind taking it for v5.7, please go ahead.
prev parent reply other threads:[~2020-04-02 13:04 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-29 14:12 [RFC PATCH] arm64: remove CONFIG_DEBUG_ALIGN_RODATA feature Ard Biesheuvel
2020-03-30 11:29 ` Mark Rutland
2020-03-30 12:36 ` Ard Biesheuvel
2020-03-30 13:51 ` Will Deacon
2020-03-30 13:53 ` Ard Biesheuvel
2020-03-30 13:59 ` Robin Murphy
2020-03-30 14:04 ` Will Deacon
2020-03-30 14:22 ` Ard Biesheuvel
2020-03-30 14:28 ` Will Deacon
2020-03-30 14:32 ` Ard Biesheuvel
2020-04-02 11:30 ` Catalin Marinas
2020-04-02 12:17 ` Mark Rutland
2020-04-03 7:07 ` Will Deacon
2020-04-03 8:58 ` Ard Biesheuvel
2020-05-05 10:44 ` Will Deacon
2020-05-07 13:43 ` Catalin Marinas
2020-03-30 13:57 ` Laura Abbott
2020-04-02 11:15 ` Catalin Marinas
2020-04-02 11:24 ` Ard Biesheuvel [this message]
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=CAMj1kXFTnqZHWZX5yhkG4+pd04JzGriFW6gjBrAnQ-LQQmEi3Q@mail.gmail.com \
--to=ardb@kernel.org \
--cc=catalin.marinas@arm.com \
--cc=kernel-hardening@lists.openwall.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=will@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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).