linux-kernel - Re: [PATCH v6 01/10] x86/retpoline: Add initial retpoline support

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Date:   Mon, 8 Jan 2018 12:45:44 -0000
From:   "David Woodhouse" <dwmw2@...radead.org>
To:     "Peter Zijlstra" <peterz@...radead.org>
Cc:     "David Woodhouse" <dwmw2@...radead.org>,
        "Andi Kleen" <ak@...ux.intel.com>, "Paul Turner" <pjt@...gle.com>,
        "LKML" <linux-kernel@...r.kernel.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Greg Kroah-Hartman" <gregkh@...ux-foundation.org>,
        "Tim Chen" <tim.c.chen@...ux.intel.com>,
        "Dave Hansen" <dave.hansen@...el.com>, tglx@...utronix.de,
        "Kees Cook" <keescook@...gle.com>,
        "Rik van Riel" <riel@...hat.com>,
        "Andy Lutomirski" <luto@...capital.net>,
        "Jiri Kosina" <jikos@...nel.org>, gnomes@...rguk.ukuu.org.uk
Subject: Re: [PATCH v6 01/10] x86/retpoline: Add initial retpoline support


> On Mon, Jan 08, 2018 at 10:53:02AM +0000, David Woodhouse wrote:
>> On Mon, 2018-01-08 at 11:45 +0100, Peter Zijlstra wrote:
>> >
>> >
>> > Should this not use local name labels instead?
>> >
>> > .macro RETPOLINE_JMP reg:req
>> >         call    .Ldo_rop_\@
>> > .Lspec_trap_\@:
>> >         pause
>> >         jmp .Lspec_trap_\@
>> > .Ldo_rop_\@:
>> >         mov     \reg, (%_ASM_SP)
>> >         ret
>> > .endm
>>
>> Not if you want to be able to use them twice in the same .S file.
>
> Should work fine, the \@ expands to a per-instance magic thing IIRC. All
> the PTI helpers do this too and that works just fine, see
> arch/x86/entry/calling.h
>

Ah, OK. Will do that when home in a few hours then.

-- 
dwmw2