From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755331AbeDCWjb (ORCPT ); Tue, 3 Apr 2018 18:39:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:50768 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753801AbeDCWj3 (ORCPT ); Tue, 3 Apr 2018 18:39:29 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3DFCD2133F 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@kernel.org, LKML Cc: Borislav Petkov , Dominik Brodowski , Andy Lutomirski Subject: [PATCH] x86/entry/64: Drop idtentry's manual stack switch for user entries Date: Tue, 3 Apr 2018 15:39:26 -0700 Message-Id: <90aab80c1f906e70742eaa4512e3c9b5e62d59d4.1522794757.git.luto@kernel.org> X-Mailer: git-send-email 2.14.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org For non-paranoid entries, idtentry knows how to switch from the kernel stack to the user stack, as does error_entry. This results in pointless duplication and code bloat. Make idtentry stop thinking about stacks for non-paranoid entries. This reduces text size by 5377 bytes. This goes back to commit 7f2590a110b8 ("x86/entry/64: Use a per-CPU trampoline stack for IDT entries"). Signed-off-by: Andy Lutomirski --- Hi all- I have more cleanups in the works, but this is enough of I win by itself that I wanted to get it out there. arch/x86/entry/entry_64.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 9b114675fbc0..e237913a056b 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -908,7 +908,7 @@ ENTRY(\sym) pushq $-1 /* ORIG_RAX: no syscall to restart */ .endif - .if \paranoid < 2 + .if \paranoid == 1 testb $3, CS-ORIG_RAX(%rsp) /* If coming from userspace, switch stacks */ jnz .Lfrom_usermode_switch_stack_\@ .endif @@ -955,7 +955,7 @@ ENTRY(\sym) jmp error_exit .endif - .if \paranoid < 2 + .if \paranoid == 1 /* * Entry from userspace. Switch stacks and treat it * as a normal entry. This means that paranoid handlers -- 2.14.3