From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Jann Horn <jannh@google.com>
Cc: Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
the arch/x86 maintainers <x86@kernel.org>,
kernel list <linux-kernel@vger.kernel.org>
Subject: Re: x86 entry perf unwinding failure (missing IRET_REGS annotation on stack switch?)
Date: Mon, 2 Mar 2020 09:52:40 -0600 [thread overview]
Message-ID: <20200302155239.7ww7jfeu4yeevpkb@treble> (raw)
In-Reply-To: <20200302151829.brlkedossh7qs47s@treble>
On Mon, Mar 02, 2020 at 09:18:29AM -0600, Josh Poimboeuf wrote:
> > So I think on machines without X86_FEATURE_SMAP, trying to unwind from
> > the two NOPs at f41 and f42 will cause the unwinder to report an
> > error? Looking at unwind_next_frame(), "sp:(und)" without the "end:1"
> > marker seems to be reserved for errors.
I think we can blame this one on Peter ;-)
764eef4b109a ("objtool: Rewrite alt->skip_orig")
With X86_FEATURE_SMAP, alt->skip_orig gets set, which tells objtool to
skip validation of the NOPs. That has the side effect of not
propagating the ORC state to the NOPs as well.
--
Josh
next prev parent reply other threads:[~2020-03-02 15:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-01 6:02 x86 entry perf unwinding failure (missing IRET_REGS annotation on stack switch?) Jann Horn
2020-03-02 14:58 ` Peter Zijlstra
2020-03-02 15:18 ` Josh Poimboeuf
2020-03-02 15:52 ` Josh Poimboeuf [this message]
2020-04-28 7:04 ` Josh Poimboeuf
2020-04-28 12:46 ` Peter Zijlstra
2020-04-28 14:14 ` Josh Poimboeuf
2020-04-28 14:35 ` Peter Zijlstra
2020-04-28 14:16 ` Peter Zijlstra
2020-04-28 14:31 ` Josh Poimboeuf
2020-04-28 15:25 ` Peter Zijlstra
2020-04-28 15:49 ` Josh Poimboeuf
2020-04-28 15:54 ` Josh Poimboeuf
2020-04-28 16:25 ` Sean Christopherson
2020-04-28 16:33 ` Josh Poimboeuf
2020-04-28 18:28 ` Peter Zijlstra
2020-04-28 16:44 ` Peter Zijlstra
2020-04-28 17:01 ` Josh Poimboeuf
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