From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
linux-kernel@vger.kernel.org, Borislav Petkov <bp@alien8.de>
Subject: Re: [PATCH] objtool: Fix switch-table detection
Date: Thu, 8 Feb 2018 12:32:50 -0600 [thread overview]
Message-ID: <20180208183250.mtzhxani7u6hr2yy@treble> (raw)
In-Reply-To: <20180208130232.GF25235@hirez.programming.kicks-ass.net>
On Thu, Feb 08, 2018 at 02:02:32PM +0100, Peter Zijlstra wrote:
>
> Linus reported that GCC-7.3 generated a switch-table construct that
> confused objtool. It turns out that, in particular due to KASAN, it is
> possible to have unrelated .rodata usage in between the .rodata setup
> for the switch-table and the following indirect jump.
>
> The simple linear reverse search from the indirect jump would hit upon
> the KASAN .rodata usage first and fail to find a switch_table,
> resulting in a spurious 'sibling call with modified stack frame'
> warning.
>
> Fix this by creating a 'jump-stack' which we can 'unwind' during
> reversal, thereby skipping over much of the in-between code.
>
> This is not fool proof by any means, but is sufficient to make the
> known cases work. Future work would be to construct more comprehensive
> flow analysis code.
>
> Also, since Josh keeps asking, add myself to MAINTAINERS.
>
> Cc: Josh Poimboeuf <jpoimboe@redhat.com>
> Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Thanks again for helping out with objtool maintainership!
No complaints from the 0-day bot, so:
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
--
Josh
next prev parent reply other threads:[~2018-02-08 18:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-08 13:02 [PATCH] objtool: Fix switch-table detection Peter Zijlstra
2018-02-08 17:34 ` Linus Torvalds
2018-02-08 18:32 ` Josh Poimboeuf [this message]
2018-02-09 7:25 ` [tip:x86/pti] " tip-bot for Peter Zijlstra
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=20180208183250.mtzhxani7u6hr2yy@treble \
--to=jpoimboe@redhat.com \
--cc=bp@alien8.de \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.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.