From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932460AbdJZIbf (ORCPT ); Thu, 26 Oct 2017 04:31:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:40390 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932267AbdJZI1N (ORCPT ); Thu, 26 Oct 2017 04:27:13 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 664812192D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org From: Andy Lutomirski To: X86 ML Cc: Borislav Petkov , "linux-kernel@vger.kernel.org" , Brian Gerst , Dave Hansen , Linus Torvalds , Andy Lutomirski Subject: [PATCH 04/18] x86/asm/64: Simplify reg restore code in the standard IRET paths Date: Thu, 26 Oct 2017 01:26:36 -0700 Message-Id: <251f55c4996817fbea72a545b4c196a316baec20.1509006199.git.luto@kernel.org> X-Mailer: git-send-email 2.13.6 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/x86/entry/calling.h | 21 +++++++++++++++++++++ arch/x86/entry/entry_64.S | 12 ++++++------ 2 files changed, 27 insertions(+), 6 deletions(-) diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index 640aafebdc00..0b9dd8123701 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -151,6 +151,27 @@ For 32-bit we have the following conventions - kernel is built with 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 diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 1909a4e42b81..4ad40067162a 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -615,9 +615,9 @@ GLOBAL(swapgs_restore_regs_and_return_to_usermode) 1: #endif SWAPGS - RESTORE_EXTRA_REGS - RESTORE_C_REGS - REMOVE_PT_GPREGS_FROM_STACK 8 + POP_EXTRA_REGS + POP_C_REGS + addq $8, %rsp INTERRUPT_RETURN @@ -646,9 +646,9 @@ 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 INTERRUPT_RETURN ENTRY(native_iret) -- 2.13.6