linux-kernel - Re: [PATCH v2 03/12] x86/retpoline/entry: Convert entry assembler indirect jumps

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Message-ID: <1515055371.12987.83.camel@infradead.org>
Date:   Thu, 04 Jan 2018 08:42:51 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Andi Kleen <andi@...stfloor.org>, tglx@...utronix.de
Cc:     torvalds@...ux-foundation.org, gregkh@...ux-foundation.org,
        linux-kernel@...r.kernel.org, tim.c.chen@...ux.intel.com,
        Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH v2 03/12] x86/retpoline/entry: Convert entry assembler
 indirect jumps

On Wed, 2018-01-03 at 18:00 -0800, Andi Kleen wrote:
> @@ -269,8 +270,9 @@ entry_SYSCALL_64_fastpath:
>          * This call instruction is handled specially in stub_ptregs_64.
>          * It might end up jumping to the slow path.  If it jumps, RAX
>          * and all argument registers are clobbered.
> -        */
> -       call    *sys_call_table(, %rax, 8)
> +       */
> +       movq    sys_call_table(, %rax, 8), %rax
> +       NOSPEC_CALL     %rax
>  .Lentry_SYSCALL_64_after_fastpath_call:
>  
>         movq    %rax, RAX(%rsp)

Now I *know* you're working from an older version of my patches and
haven't just deliberately reverted the CET support (and alternatives?).

I fixed that mis-indentation of the closing */ and Intel were even
shipping that version in the latest pre-embargo patch tarball.

Should I post a new series and call it 'v3'? Was there anything
specific you changed other than the cosmetics like
s/CALL_THUNK/NOSPEC_CALL/ ? And obviously the fact that it stands alone
instead of being based on the IBRS microcode support?
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