From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757377AbbFPUSq (ORCPT ); Tue, 16 Jun 2015 16:18:46 -0400 Received: from mail.kernel.org ([198.145.29.136]:42603 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753814AbbFPURR (ORCPT ); Tue, 16 Jun 2015 16:17:17 -0400 From: Andy Lutomirski To: x86@kernel.org, linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Weisbecker?= , Rik van Riel , Oleg Nesterov , Denys Vlasenko , Borislav Petkov , Kees Cook , Brian Gerst , Andy Lutomirski Subject: [RFC/INCOMPLETE 07/13] x86/entry/64: Really create an error-entry-from-usermode code path Date: Tue, 16 Jun 2015 13:16:53 -0700 Message-Id: <9789d956587eb3d1746467d56ba1dce11b49fa30.1434485184.git.luto@kernel.org> X-Mailer: git-send-email 2.4.3 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 In 539f51136500 ("x86/asm/entry/64: Disentangle error_entry/exit gsbase/ebx/usermode code"), I arranged the code slightly wrong -- IRET faults would skip the code path that was intended to execute on all error entries from user mode. Fix it up. This does not fix a bug, but we'll need it, and it slightly shrinks the code. Signed-off-by: Andy Lutomirski --- arch/x86/entry/entry_64.S | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 3bb2c4302df1..33acc3dcc281 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1145,7 +1145,11 @@ ENTRY(error_entry) testb $3, CS+8(%rsp) jz error_kernelspace - /* We entered from user mode */ +error_entry_from_usermode: + /* + * We entered from user mode or we're pretending to have entered + * from user mode due to an IRET fault. + */ SWAPGS error_entry_done: @@ -1174,8 +1178,7 @@ error_kernelspace: * gsbase and proceed. We'll fix up the exception and land in * gs_change's error handler with kernel gsbase. */ - SWAPGS - jmp error_entry_done + jmp error_entry_from_usermode bstep_iret: /* Fix truncated RIP */ -- 2.4.3