From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758934Ab3IFBt2 (ORCPT ); Thu, 5 Sep 2013 21:49:28 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:24005 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758764Ab3IFBtR (ORCPT ); Thu, 5 Sep 2013 21:49:17 -0400 X-Authority-Analysis: v=2.0 cv=fJG7LOme c=1 sm=0 a=Sro2XwOs0tJUSHxCKfOySw==:17 a=Drc5e87SC40A:10 a=Ciwy3NGCPMMA:10 a=ZtygFLEOK88A:10 a=5SG0PmZfjMsA:10 a=bbbx4UPp9XUA:10 a=meVymXHHAAAA:8 a=KGjhK52YXX0A:10 a=SJBCHd5iOokA:10 a=QyXUC8HyAAAA:8 a=a_U1oVfrAAAA:8 a=zGuplzhgmjNTnmIVghEA:9 a=k4qQewaewV0A:10 a=jeBq3FmKZ4MA:10 a=Sro2XwOs0tJUSHxCKfOySw==:117 X-Cloudmark-Score: 0 X-Authenticated-User: X-Originating-IP: 67.255.60.225 Message-Id: <20130906014915.433485667@goodmis.org> User-Agent: quilt/0.60-1 Date: Thu, 05 Sep 2013 21:48:19 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Frederic Weisbecker , Andrew Morton , Peter Zijlstra , "Paul E. McKenney" , Dave Jones , Jan Kiszka , "H. Peter Anvin" Subject: [for-next][PATCH 3/4] x86-32, ftrace: Fix static ftrace when early microcode is enabled References: <20130906014816.037690469@goodmis.org> Content-Disposition: inline; filename=0003-x86-32-ftrace-Fix-static-ftrace-when-early-microcode.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "H. Peter Anvin" Early microcode loading runs C code before paging is enabled on 32 bits. Since ftrace puts a hook into every function, that hook needs to be safe to execute in the pre-paging environment. This is currently true for dynamic ftrace but not for static ftrace. Static ftrace is obsolescent and assumed to not be performance-critical, so we can simply test that the stack pointer falls within the valid range of kernel addresses. Reported-by: Jan Kiszka Tested-by: Jan Kiszka Signed-off-by: H. Peter Anvin Signed-off-by: Steven Rostedt --- arch/x86/kernel/entry_32.S | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 2cfbc3a..f0dcb0c 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -1176,6 +1176,9 @@ ftrace_restore_flags: #else /* ! CONFIG_DYNAMIC_FTRACE */ ENTRY(mcount) + cmpl $__PAGE_OFFSET, %esp + jb ftrace_stub /* Paging not enabled yet? */ + cmpl $0, function_trace_stop jne ftrace_stub -- 1.7.10.4