From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Dave Hansen <dave.hansen@intel.com>,
Ashok Raj <ashok.raj@intel.com>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg KH <gregkh@linuxfoundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Andi Kleen <ak@linux.intel.com>,
Arjan Van De Ven <arjan.van.de.ven@intel.com>,
Dan Williams <dan.j.williams@intel.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Jun Nakajima <jun.nakajima@intel.com>,
Asit Mallick <asit.k.mallick@intel.com>
Subject: Re: [PATCH 4/7] x86,nospec: Annotate indirect calls/jumps
Date: Thu, 1 Feb 2018 16:30:05 +0100 [thread overview]
Message-ID: <20180201153005.GY2249@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180201152134.63e553pvoq7mbm4p@treble>
On Thu, Feb 01, 2018 at 09:21:34AM -0600, Josh Poimboeuf wrote:
> On Thu, Feb 01, 2018 at 04:13:48PM +0100, Peter Zijlstra wrote:
> > arch/x86/entry/.tmp_entry_64.o: warning: objtool: .altinstr_replacement+0x19: indirect jump found in RETPOLINE build
>
> Right, objtool was recently made smarter, such that it actually decodes
> the ignored alternatives.
I think it always did, you just ignored the alternatives for the code
flow stuff.
> The check for that warning needs to also check that insn->ignore isn't
> set.
So I tried to keep the two annotations independent, thinking the code
flow ignore would eventually go away when we got smarter about it. It
even has a comment about that:
/*
* FIXME: For now, just ignore any alternatives which add retpolines. This is
* a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline.
* But it at least allows objtool to understand the control flow *around* the
* retpoline.
*/
So I'm not seeing how making retpoline_safe depend on nospec_ignores is
a good thing.
next prev parent reply other threads:[~2018-02-01 15:30 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-01 14:34 [PATCH 0/7] objtool: retpoline validation Peter Zijlstra
2018-02-01 14:34 ` [PATCH 1/7] objtool: Use existing global variables for options Peter Zijlstra
2018-02-01 14:34 ` [PATCH 2/7] objtool: Add retpoline validation Peter Zijlstra
2018-02-01 14:34 ` [PATCH 3/7] objtool: Add module specific retpoline rules Peter Zijlstra
2018-02-01 14:34 ` [PATCH 4/7] x86,nospec: Annotate indirect calls/jumps Peter Zijlstra
2018-02-01 14:55 ` David Woodhouse
2018-02-01 15:11 ` Peter Zijlstra
2018-02-01 15:13 ` Peter Zijlstra
2018-02-01 15:21 ` Josh Poimboeuf
2018-02-01 15:30 ` Peter Zijlstra [this message]
2018-02-01 14:34 ` [PATCH 5/7] x86/paravirt: Annotate indirect calls Peter Zijlstra
2018-02-01 14:34 ` [PATCH 6/7] x86: Annotate indirect jump in head_64.S Peter Zijlstra
2018-02-01 14:34 ` [PATCH 7/7] x86,sme: Annotate indirect call Peter Zijlstra
2018-02-01 15:28 ` [PATCH 0/7] objtool: retpoline validation Josh Poimboeuf
2018-02-01 15:32 ` David Woodhouse
2018-02-01 15:40 ` Peter Zijlstra
2018-02-01 16:51 ` David Woodhouse
2018-02-01 17:14 ` Peter Zijlstra
2018-02-01 17:43 ` Josh Poimboeuf
2018-02-01 18:16 ` Tim Chen
2018-02-06 21:23 ` David Woodhouse
2018-02-01 15:32 ` Peter Zijlstra
2018-02-01 19:36 ` Peter Zijlstra
2018-02-01 15:50 ` Josh Poimboeuf
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