From: rabin@rab.in (Rabin Vincent)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] arm: use fixmap for text patching when text is RO
Date: Thu, 10 Apr 2014 21:34:46 +0200 [thread overview]
Message-ID: <20140410193433.GA22746@debian> (raw)
In-Reply-To: <1396879071.3654.43.camel@linaro1.home>
On Mon, Apr 07, 2014 at 02:57:51PM +0100, Jon Medhurst (Tixy) wrote:
> How does fixmap cope with cache colouring? Looking at the implementation
> it looks like it doesn't and so fixmap use on ARM is possibly buggy.
>
> For the text patching case where we know there are no writeable mappings
> [1] this should be OK if we used set_fixmap_nocache here, so long as we
> also invalidated the dcache later for the proper virtual address.
OK. The dcache invalidation for the proper virtual address is btw
already there via the call to flush_icache_range().
> [1] Can we know there are no writeable mappings though, the ftrace code
> modifying patches from Kees Cook have there own way of modifying text
> code permissions.
The ftrace patches does the modifications and the cache cleaning in
stop_machine(), so there should not be any dirty cache lines from those
writable mappings when we set up and write to these fixmaps. Do you
still see a problem?
next prev parent reply other threads:[~2014-04-10 19:34 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-04 21:27 [PATCH 1/2] arm: fixmap: implement __set_fixmap() Rabin Vincent
2014-04-04 21:27 ` [PATCH 2/2] arm: use fixmap for text patching when text is RO Rabin Vincent
2014-04-07 13:57 ` Jon Medhurst (Tixy)
2014-04-07 18:04 ` Kees Cook
2014-04-08 9:31 ` Jon Medhurst (Tixy)
2014-04-10 19:34 ` Rabin Vincent [this message]
2014-04-23 21:09 ` Kees Cook
2014-04-23 22:51 ` Doug Anderson
2014-04-24 21:28 ` [PATCHv2 " Rabin Vincent
2014-04-25 0:52 ` [PATCH 1/2] arm: fixmap: implement __set_fixmap() Doug Anderson
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=20140410193433.GA22746@debian \
--to=rabin@rab.in \
--cc=linux-arm-kernel@lists.infradead.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).