From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932468AbdJ0ULF (ORCPT ); Fri, 27 Oct 2017 16:11:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:56064 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932384AbdJ0ULD (ORCPT ); Fri, 27 Oct 2017 16:11:03 -0400 Date: Fri, 27 Oct 2017 22:11:05 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: X86 ML , "linux-kernel@vger.kernel.org" , Brian Gerst , Dave Hansen , Linus Torvalds Subject: Re: [PATCH 06/18] x86/asm/64: Use pop instead of movq in syscall_return_via_sysret Message-ID: <20171027201105.GC12039@nazgul.tnic> References: <84b7fb69c1d05068b6c13d63b06eb322383636b7.1509006199.git.luto@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <84b7fb69c1d05068b6c13d63b06eb322383636b7.1509006199.git.luto@kernel.org> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Oct 26, 2017 at 01:26:38AM -0700, Andy Lutomirski wrote: > Saves 64 bytes. > > Signed-off-by: Andy Lutomirski > --- > arch/x86/entry/entry_64.S | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S > index d6404a613df4..9dafafa3e0ec 100644 > --- a/arch/x86/entry/entry_64.S > +++ b/arch/x86/entry/entry_64.S > @@ -313,10 +313,18 @@ return_from_SYSCALL_64: > */ > syscall_return_via_sysret: > /* rcx and r11 are already restored (see code above) */ > - RESTORE_EXTRA_REGS > - RESTORE_C_REGS_EXCEPT_RCX_R11 > - movq RSP(%rsp), %rsp > UNWIND_HINT_EMPTY > + POP_EXTRA_REGS > + popq %rsi /* skip r11 */ > + popq %r10 > + popq %r9 > + popq %r8 > + popq %rax > + popq %rsi /* skip rcx */ > + popq %rdx > + popq %rsi > + popq %rdi > + movq RSP-ORIG_RAX(%rsp), %rsp > USERGS_SYSRET64 > END(entry_SYSCALL_64) > > -- Reviewed-by: Borislav Petkov -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --