From: Peter Zijlstra <peterz@infradead.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Josh Poimboeuf <jpoimboe@redhat.com>,
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>,
Jason Baron <jbaron@akamai.com>,
Tom Lendacky <thomas.lendacky@amd.com>,
Borislav Petkov <bp@suse.de>
Subject: Re: [PATCH 08/24] x86,sme: Annotate indirect call
Date: Mon, 29 Jan 2018 18:50:34 +0100 [thread overview]
Message-ID: <20180129175034.GF2295@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180129174952.GI2228@hirez.programming.kicks-ass.net>
On Mon, Jan 29, 2018 at 06:49:52PM +0100, Peter Zijlstra wrote:
> On Fri, Jan 26, 2018 at 10:37:30AM +0000, David Woodhouse wrote:
> > On Tue, 2018-01-23 at 16:25 +0100, Peter Zijlstra wrote:
> > > This is boot code, we run this _way_ before userspace comes along to
> > > poison our branch predictor.
> >
> > Hm, objtool knows about sections, doesn't it? Why it is whining about
> > indirect jumps in inittext anyway?
> >
> > In fact, why are we even *doing* retpolines in inittext? Not that we
> > are; since we flipped the ALTERNATIVE logic around, at that point we
> > still have the 'oldinstr' which is a bare jmp anyway. We might as well
> > do this:
> >
> > --- a/include/linux/init.h
> > +++ b/include/linux/init.h
> > @@ -37,10 +37,15 @@
> > * as gcc otherwise puts the data into the bss section and not into the init
> > * section.
> > */
> > +#if defined(RETPOLINE) && !defined(MODULE)
> > +#define __noretpoline __attribute__((indirect_branch("keep")))
> > +#else
> > +#define __noretpoline
> > +#endif
Clearly I cannot read...
> > /* These are for everybody (although not all archs will actually
> > discard it in modules) */
> > -#define __init __section(.init.text) __cold __inittrace __latent_entropy
> > +#define __init __section(.init.text) __cold __inittrace __latent_entropy __noretpoline
>
> We run module __init text concurrently with userspace.
next prev parent reply other threads:[~2018-01-29 17:50 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-23 15:25 [PATCH 00/24] objtool: retpoline and asm-goto validation Peter Zijlstra
2018-01-23 15:25 ` [PATCH 01/24] objtool: Use existing global variables for options Peter Zijlstra
2018-01-23 15:25 ` [PATCH 02/24] objtool: Add retpoline validation Peter Zijlstra
2018-01-23 18:21 ` Borislav Petkov
2018-01-26 9:54 ` David Woodhouse
2018-01-23 15:25 ` [PATCH 03/24] x86/paravirt: Annotate indirect calls Peter Zijlstra
2018-01-25 10:02 ` David Woodhouse
2018-01-25 10:22 ` Peter Zijlstra
2018-01-25 10:26 ` Juergen Gross
2018-01-25 10:52 ` David Woodhouse
2018-01-25 11:35 ` Peter Zijlstra
2018-01-26 9:57 ` David Woodhouse
2018-01-29 17:58 ` Josh Poimboeuf
2018-01-29 18:09 ` David Woodhouse
2018-01-29 18:17 ` Peter Zijlstra
2018-01-29 18:38 ` Josh Poimboeuf
2018-01-29 19:21 ` Peter Zijlstra
2018-01-30 16:02 ` Josh Poimboeuf
2018-01-31 4:13 ` [PATCH] x86/paravirt: Remove 'noreplace-paravirt' cmdline option Josh Poimboeuf
2018-01-31 5:59 ` Juergen Gross
2018-01-31 9:42 ` [tip:x86/pti] " tip-bot for Josh Poimboeuf
2018-01-23 15:25 ` [PATCH 04/24] x86,nospec: Annotate indirect calls/jumps Peter Zijlstra
2018-01-26 10:19 ` David Woodhouse
2018-01-29 17:44 ` Peter Zijlstra
2018-01-23 15:25 ` [PATCH 05/24] x86: Annotate indirect jump in head_64.S Peter Zijlstra
2018-01-26 10:24 ` David Woodhouse
2018-01-23 15:25 ` [PATCH 06/24] x86,kvm: Fix indirect calls in emulator Peter Zijlstra
2018-01-23 20:28 ` Borislav Petkov
2018-01-23 20:48 ` David Woodhouse
2018-01-24 10:35 ` Peter Zijlstra
2018-01-24 10:43 ` Paolo Bonzini
2018-01-25 9:34 ` Peter Zijlstra
2018-01-25 9:49 ` David Woodhouse
2018-01-26 10:57 ` Paolo Bonzini
2018-01-23 15:25 ` [PATCH 07/24] x86,vmx: Fix indirect call Peter Zijlstra
2018-01-25 9:36 ` Peter Zijlstra
2018-01-23 15:25 ` [PATCH 08/24] x86,sme: Annotate " Peter Zijlstra
2018-01-26 10:37 ` David Woodhouse
2018-01-29 17:49 ` Peter Zijlstra
2018-01-29 17:50 ` Peter Zijlstra [this message]
2018-01-31 9:29 ` Peter Zijlstra
2018-01-31 15:04 ` Josh Poimboeuf
2018-01-31 16:00 ` Peter Zijlstra
2018-01-23 15:25 ` [PATCH 09/24] jump_label: Add branch hints to static_branch_{un,}likely() Peter Zijlstra
2018-01-24 18:46 ` Borislav Petkov
2018-01-23 15:25 ` [PATCH 10/24] sched: Optimize ttwu_stat() Peter Zijlstra
2018-01-23 15:25 ` [PATCH 11/24] x86: Reindent _static_cpu_has Peter Zijlstra
2018-01-23 15:25 ` [PATCH 12/24] x86: Update _static_cpu_has to use all named variables Peter Zijlstra
2018-01-25 19:31 ` Borislav Petkov
2018-01-23 15:25 ` [PATCH 13/24] objtool: Implement base jump_assert support Peter Zijlstra
2018-01-26 10:45 ` David Woodhouse
2018-01-23 15:25 ` [PATCH 14/24] x86: Add a type field to alt_instr Peter Zijlstra
2018-01-23 15:25 ` [PATCH 15/24] x86: Annotate static_cpu_has alternative Peter Zijlstra
2018-01-23 15:25 ` [PATCH 16/24] objtool: Implement jump_assert for _static_cpu_has() Peter Zijlstra
2018-01-23 15:25 ` [PATCH 17/24] objtool: Introduce special_type Peter Zijlstra
2018-01-23 15:25 ` [PATCH 18/24] objtool: More complex static jump implementation Peter Zijlstra
2018-01-23 15:25 ` [PATCH 19/24] objtool: Even more complex static block checks Peter Zijlstra
2018-01-23 15:25 ` [PATCH 20/24] objtool: Another static block fail Peter Zijlstra
2018-01-29 22:52 ` Josh Poimboeuf
2018-01-30 9:56 ` Peter Zijlstra
2018-01-31 3:12 ` Josh Poimboeuf
2018-01-31 10:01 ` Peter Zijlstra
2018-01-31 10:07 ` David Woodhouse
2018-01-31 10:27 ` Peter Zijlstra
2018-01-23 15:26 ` [PATCH 21/24] objtool: Skip static assert when KCOV/KASAN Peter Zijlstra
2018-01-23 15:26 ` [PATCH 22/24] x86/jump_label: Implement arch_static_assert() Peter Zijlstra
2018-01-23 15:26 ` [PATCH 23/24] x86: Force asm-goto Peter Zijlstra
2018-01-23 15:26 ` [PATCH 24/24] x86: Remove FAST_FEATURE_TESTS Peter Zijlstra
2018-01-23 15:42 ` [PATCH 00/24] objtool: retpoline and asm-goto validation Peter Zijlstra
2018-01-23 15:57 ` David Woodhouse
2018-01-23 16:03 ` Peter Zijlstra
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