Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933555AbdLVI77 (ORCPT ); Fri, 22 Dec 2017 03:59:59 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:36922 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933518AbdLVI7x (ORCPT ); Fri, 22 Dec 2017 03:59:53 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski , Borislav Petkov , Brian Gerst , Dave Hansen , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.14 038/159] x86/entry/64: Simplify reg restore code in the standard IRET paths Date: Fri, 22 Dec 2017 09:45:23 +0100 Message-Id: <20171222084625.803259682@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171222084623.668990192@linuxfoundation.org> References: <20171222084623.668990192@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2257 Lines: 91 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Lutomirski commit e872045bfd9c465a8555bab4b8567d56a4d2d3bb upstream. The old code restored all the registers with movq instead of pop. In theory, this was done because some CPUs have higher movq throughput, but any gain there would be tiny and is almost certainly outweighed by the higher text size. This saves 96 bytes of text. Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/ad82520a207ccd851b04ba613f4f752b33ac05f7.1509609304.git.luto@kernel.org Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/calling.h | 21 +++++++++++++++++++++ arch/x86/entry/entry_64.S | 12 ++++++------ 2 files changed, 27 insertions(+), 6 deletions(-) --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -152,6 +152,27 @@ For 32-bit we have the following convent UNWIND_HINT_REGS offset=\offset extra=0 .endm + .macro POP_EXTRA_REGS + popq %r15 + popq %r14 + popq %r13 + popq %r12 + popq %rbp + popq %rbx + .endm + + .macro POP_C_REGS + popq %r11 + popq %r10 + popq %r9 + popq %r8 + popq %rax + popq %rcx + popq %rdx + popq %rsi + popq %rdi + .endm + .macro RESTORE_C_REGS_HELPER rstor_rax=1, rstor_rcx=1, rstor_r11=1, rstor_r8910=1, rstor_rdx=1 .if \rstor_r11 movq 6*8(%rsp), %r11 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -619,9 +619,9 @@ GLOBAL(swapgs_restore_regs_and_return_to 1: #endif SWAPGS - RESTORE_EXTRA_REGS - RESTORE_C_REGS - REMOVE_PT_GPREGS_FROM_STACK 8 + POP_EXTRA_REGS + POP_C_REGS + addq $8, %rsp /* skip regs->orig_ax */ INTERRUPT_RETURN @@ -651,9 +651,9 @@ GLOBAL(restore_regs_and_return_to_kernel ud2 1: #endif - RESTORE_EXTRA_REGS - RESTORE_C_REGS - REMOVE_PT_GPREGS_FROM_STACK 8 + POP_EXTRA_REGS + POP_C_REGS + addq $8, %rsp /* skip regs->orig_ax */ INTERRUPT_RETURN ENTRY(native_iret)