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From: David Woodhouse <dwmw2@infradead.org>
To: Eric Biggers <ebiggers3@gmail.com>
Cc: Andi Kleen <ak@linux.intel.com>, Paul Turner <pjt@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg Kroah-Hartman <gregkh@linux-foundation.org>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Dave Hansen <dave.hansen@intel.com>,
	tglx@linutronix.de, Kees Cook <keescook@google.com>,
	Rik van Riel <riel@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Jiri Kosina <jikos@kernel.org>,
	gnomes@lxorguk.ukuu.org.uk
Subject: Re: [PATCH v5 02/12] x86/retpoline: Add initial retpoline support
Date: Sat, 06 Jan 2018 19:17:53 +0000	[thread overview]
Message-ID: <1515266273.29312.258.camel@infradead.org> (raw)
In-Reply-To: <20180106183541.GA8258@zzz.localdomain>

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On Sat, 2018-01-06 at 10:35 -0800, Eric Biggers wrote:
> On Sat, Jan 06, 2018 at 11:49:24AM +0000, David Woodhouse wrote:
> > 
> > +/*
> > + * NOSPEC_JMP and NOSPEC_CALL macros can be used instead of a simple
> > + * indirect jmp/call which may be susceptible to the Spectre variant 2
> > + * attack.
> > + */
>
> Can be, or must be?

Can be is fine. It isn't necessarily the case that all indirect
branches MUST be changed. Although we *have* been auditing the kernel
binary and looking for them, some of them can stay as they are.


> Would it make any sense to name these INDIRECT_JMP and INDIRECT_CALL instead?
> NOSPEC_ seems to describe how it needs to be implemented on some CPUs, as
> opposed to what the user wants to do (make an indirect jump or call).

While NOSPEC_CALL explains why you're using the macro instead of just
'call'. I think this is fine. I'd rather not do too much bikeshedding
over the names.

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  reply	other threads:[~2018-01-06 19:18 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-06 11:49 [PATCH v5 00/12] Retpoline: Avoid speculative indirect calls in kernel David Woodhouse
2018-01-06 11:49 ` [PATCH v5 01/12] x86/spectre: Add X86_BUG_SPECTRE_V[12] David Woodhouse
2018-01-06 21:05   ` [tip:x86/pti] x86/cpufeatures: " tip-bot for David Woodhouse
2018-01-06 11:49 ` [PATCH v5 02/12] x86/retpoline: Add initial retpoline support David Woodhouse
2018-01-06 17:32   ` David Woodhouse
2018-01-06 18:05   ` [PATCH v5.1 " David Woodhouse
2018-01-06 18:35   ` [PATCH v5 " Eric Biggers
2018-01-06 19:17     ` David Woodhouse [this message]
2018-01-06 21:16   ` Andrew Cooper
2018-01-06 21:21     ` Woodhouse, David
2018-01-07  1:44       ` Tom Lendacky
2018-01-06 21:23     ` Thomas Gleixner
2018-01-06 21:34       ` Andrew Cooper
2018-01-06 21:49         ` Woodhouse, David
2018-01-06 11:49 ` [PATCH v5 03/12] x86/retpoline/crypto: Convert crypto assembler indirect jumps David Woodhouse
2018-01-06 11:49 ` [PATCH v5 04/12] x86/retpoline/entry: Convert entry " David Woodhouse
2018-01-06 11:49 ` [PATCH v5 05/12] x86/retpoline/ftrace: Convert ftrace " David Woodhouse
2018-01-06 18:13   ` Linus Torvalds
2018-01-06 19:53     ` Thomas Gleixner
2018-01-07  1:27       ` Linus Torvalds
2018-01-06 11:49 ` [PATCH v5 06/12] x86/retpoline/hyperv: Convert " David Woodhouse
2018-01-06 11:49 ` [PATCH v5 07/12] x86/retpoline/xen: Convert Xen hypercall " David Woodhouse
2018-01-06 11:49 ` [PATCH v5 08/12] x86/retpoline/checksum32: Convert assembler " David Woodhouse
2018-01-06 11:49 ` [PATCH v5 09/12] x86/retpoline/irq32: " David Woodhouse
2018-01-06 11:49 ` [PATCH v5 10/12] x86/retpoline: Add boot time option to disable retpoline David Woodhouse
2018-01-06 11:49 ` [PATCH v5 11/12] x86/retpoline: Exclude objtool with retpoline David Woodhouse
2018-01-06 11:49 ` [PATCH v5 12/12] retpoline/modpost: Quieten MODVERSION retpoline build David Woodhouse
2018-01-07  0:10 ` [RFC PATCH 13/12] Retpoline vs. CONFIG_TRIM_UNUSED_SYMBOLS David Woodhouse
2018-01-07  8:03   ` David Woodhouse
2018-01-07 15:09     ` Lu, Hongjiu
2018-01-07 17:32       ` David Woodhouse
2018-01-07 17:57         ` Lu, Hongjiu
2018-01-07 18:18           ` Thomas Gleixner
2018-01-07 18:32             ` Lu, Hongjiu
2018-01-07 20:57               ` David Woodhouse
2018-01-07 22:16               ` David Woodhouse

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