Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752078AbbF2TfB (ORCPT ); Mon, 29 Jun 2015 15:35:01 -0400 Received: from mail.kernel.org ([198.145.29.136]:41565 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753197AbbF2TeJ (ORCPT ); Mon, 29 Jun 2015 15:34:09 -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 , paulmck@linux.vnet.ibm.com, Andy Lutomirski Subject: [PATCH v4 10/17] x86/entry/64: Really create an error-entry-from-usermode code path Date: Mon, 29 Jun 2015 12:33:42 -0700 Message-Id: <88b8446ce3af6822db02b5f983b8740f8365e9b4.1435602481.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 Content-Length: 1728 Lines: 60 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 | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 141a5d49dddc..cd9cbc62159c 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -1145,9 +1145,14 @@ ENTRY(error_entry) testb $3, CS+8(%rsp) jz error_kernelspace - /* We entered from user mode */ +error_entry_from_usermode_swapgs: + /* + * We entered from user mode or we're pretending to have entered + * from user mode due to an IRET fault. + */ SWAPGS +error_entry_from_usermode_after_swapgs: error_entry_done: TRACE_IRQS_OFF ret @@ -1174,8 +1179,7 @@ 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_swapgs bstep_iret: /* Fix truncated RIP */ @@ -1198,7 +1202,7 @@ error_bad_iret: call fixup_bad_iret mov %rax, %rsp decl %ebx - jmp error_entry_done + jmp error_entry_from_usermode_after_swapgs END(error_entry) -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/