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From: Andy Lutomirski <luto@amacapital.net>
Date: Wed, 18 Feb 2015 15:26:28 -0800
Message-ID: <CALCETrWT-PVn5Yp9qTPDO77Eb0AsR4DV7_Ph597U=ZB7+LR6aw@mail.gmail.com>
Subject: Re: [PATCH 02/11] x86: code shrink in paranoid_exit
To: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
        Oleg Nesterov <oleg@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, X86 ML <x86@kernel.org>,
        Alexei Starovoitov <ast@plumgrid.com>, Will Drewry <wad@chromium.org>,
        Kees Cook <keescook@chromium.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Wed, Jan 14, 2015 at 1:48 PM, Denys Vlasenko <dvlasenk@redhat.com> wrote:
> RESTORE_EXTRA_REGS + RESTORE_C_REGS looks small, but it's
> a lot of instructions (fourteen). Let's reuse them.
>
> Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
> CC: Linus Torvalds <torvalds@linux-foundation.org>
> CC: Oleg Nesterov <oleg@redhat.com>
> CC: Borislav Petkov <bp@alien8.de>
> CC: "H. Peter Anvin" <hpa@zytor.com>
> CC: Andy Lutomirski <luto@amacapital.net>
> CC: Frederic Weisbecker <fweisbec@gmail.com>
> CC: X86 ML <x86@kernel.org>
> CC: Alexei Starovoitov <ast@plumgrid.com>
> CC: Will Drewry <wad@chromium.org>
> CC: Kees Cook <keescook@chromium.org>
> CC: linux-kernel@vger.kernel.org
> ---
>  arch/x86/kernel/entry_64.S | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
> index a21b5b3..f5e815e 100644
> --- a/arch/x86/kernel/entry_64.S
> +++ b/arch/x86/kernel/entry_64.S
> @@ -1270,12 +1270,10 @@ ENTRY(paranoid_exit)
>         jnz paranoid_restore
>         TRACE_IRQS_IRETQ 0
>         SWAPGS_UNSAFE_STACK
> -       RESTORE_EXTRA_REGS
> -       RESTORE_C_REGS
> -       REMOVE_PT_GPREGS_FROM_STACK 8
> -       INTERRUPT_RETURN
> +       jmp paranoid_restore1
>  paranoid_restore:
>         TRACE_IRQS_IRETQ_DEBUG 0
> +paranoid_restore1:
>         RESTORE_EXTRA_REGS
>         RESTORE_C_REGS
>         REMOVE_PT_GPREGS_FROM_STACK 8
> --
> 1.8.1.4
>

Applied, but I changed the label names.

-- 
Andy Lutomirski
AMA Capital Management, LLC