From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: alexandre.chartre@oracle.com, linux-kernel@vger.kernel.org,
jthierry@redhat.com, tglx@linutronix.de, x86@kernel.org
Subject: Re: [RFC][PATCH 5/7] x86/speculation: Change __FILL_RETURN_BUFFER to work with objtool
Date: Sun, 19 Apr 2020 20:58:38 +0200 [thread overview]
Message-ID: <20200419185838.GX20696@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200419165519.wstqpqmvyom4yh3r@treble>
On Sun, Apr 19, 2020 at 11:55:19AM -0500, Josh Poimboeuf wrote:
> On Sun, Apr 19, 2020 at 11:52:00AM -0500, Josh Poimboeuf wrote:
> > Are we still planning to warn about stack changes inside an alternative?
> > If so then this would still fail...
> >
> > In this case I think it should be safe, but I'm not sure how we can
> > ensure that will always be the case for other alternatives.
> >
> > And do the ORC entries actually work for this? As far as I can tell,
> > they would be associated with the .altinstructions section and not
> > .text, so it wouldn't work.
>
> My preference would be to move RSB stuffing out-of-line too, like you
> did the retpolines. Or use static branches. Then we could add an
> objtool warning to prevent stack changes in alternatives.
I effectively did the static_branch thing, but with an alternative, it's
in the last patch, due to me being a moron and not refreshing the stack
before sending it out.
next prev parent reply other threads:[~2020-04-19 18:58 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 15:07 [RFC][PATCH 0/7] objtool vs retpoline Peter Zijlstra
2020-04-16 15:07 ` [RFC][PATCH 1/7] objtool: is_fentry_call() crashes if call has no destination Peter Zijlstra
2020-04-16 15:07 ` [RFC][PATCH 2/7] objtool: UNWIND_HINT_RET_OFFSET should not check registers Peter Zijlstra
2020-04-16 15:07 ` [RFC][PATCH 3/7] objtool: Allow branches within the same alternative Peter Zijlstra
2020-04-19 16:32 ` Josh Poimboeuf
2020-04-19 19:27 ` Peter Zijlstra
2020-04-16 15:07 ` [RFC][PATCH 4/7] objtool: Add support for intra-function calls Peter Zijlstra
2020-04-19 16:41 ` Josh Poimboeuf
2020-04-23 11:40 ` Peter Zijlstra
2020-04-16 15:07 ` [RFC][PATCH 5/7] x86/speculation: Change __FILL_RETURN_BUFFER to work with objtool Peter Zijlstra
2020-04-19 16:51 ` Josh Poimboeuf
2020-04-19 16:55 ` Josh Poimboeuf
2020-04-19 18:58 ` Peter Zijlstra [this message]
2020-04-16 15:07 ` [RFC][PATCH 6/7] x86/retpoline: Out-of-line retpoline Peter Zijlstra
2020-04-16 15:22 ` Peter Zijlstra
2020-04-16 15:07 ` [RFC][PATCH 7/7] x86/nospec: Remove ANNOTATE_NOSPEC_ALTERNATIVE Peter Zijlstra
2020-04-16 15:32 ` [RFC][PATCH 0/7] objtool vs retpoline Peter Zijlstra
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