From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 58305C55185 for ; Wed, 22 Apr 2020 16:28:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 315BD2082E for ; Wed, 22 Apr 2020 16:28:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726688AbgDVQ2B (ORCPT ); Wed, 22 Apr 2020 12:28:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:42652 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726423AbgDVQ1w (ORCPT ); Wed, 22 Apr 2020 12:27:52 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 84D1E20776; Wed, 22 Apr 2020 16:27:51 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.93) (envelope-from ) id 1jRIE2-000O4K-FH; Wed, 22 Apr 2020 12:27:50 -0400 Message-Id: <20200422162750.350373278@goodmis.org> User-Agent: quilt/0.65 Date: Wed, 22 Apr 2020 12:25:40 -0400 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , tglx@linutronix.de, jpoimboe@redhat.com, x86@kernel.org, mhiramat@kernel.org, mbenes@suse.cz, jthierry@redhat.com, alexandre.chartre@oracle.com Subject: [PATCH 1/3] x86/ftrace: Make non direct case the default in ftrace_regs_caller References: <20200422162539.808362933@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Steven Rostedt (VMware)" If a direct function is hooked along with one of the ftrace registered functions, then the ftrace_regs_caller is attached to the function that shares the direct hook as well as the ftrace hook. The ftrace_regs_caller will call ftrace_ops_list_func() that iterates through all the registered ftrace callbacks, and if there's a direct callback attached to that function, the direct ftrace_ops callback is called to notify that ftrace_regs_caller to return to the direct caller instead of going back to the function that called it. But this is a very uncommon case. Currently, the code has it as the default case. Modify ftrace_regs_caller to make the default case (the non jump) to just return normally, and have the jump to the handling of the direct caller. Signed-off-by: Steven Rostedt (VMware) --- arch/x86/kernel/ftrace_64.S | 31 +++++++++++++++---------------- 1 file changed, 15 insertions(+), 16 deletions(-) diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index 9738ed23964e..c93ee7195af0 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -241,22 +241,9 @@ SYM_INNER_LABEL(ftrace_regs_call, SYM_L_GLOBAL) */ movq ORIG_RAX(%rsp), %rax testq %rax, %rax - jz 1f + jnz 1f - /* Swap the flags with orig_rax */ - movq MCOUNT_REG_SIZE(%rsp), %rdi - movq %rdi, MCOUNT_REG_SIZE-8(%rsp) - movq %rax, MCOUNT_REG_SIZE(%rsp) - - restore_mcount_regs 8 - /* Restore flags */ - popfq - -SYM_INNER_LABEL(ftrace_regs_caller_ret, SYM_L_GLOBAL); - UNWIND_HINT_RET_OFFSET - jmp ftrace_epilogue - -1: restore_mcount_regs + restore_mcount_regs /* Restore flags */ popfq @@ -266,9 +253,21 @@ SYM_INNER_LABEL(ftrace_regs_caller_ret, SYM_L_GLOBAL); * The trampoline will add the code to jump * to the return. */ -SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) +SYM_INNER_LABEL(ftrace_regs_caller_ret, SYM_L_GLOBAL) jmp ftrace_epilogue + /* Swap the flags with orig_rax */ +1: movq MCOUNT_REG_SIZE(%rsp), %rdi + movq %rdi, MCOUNT_REG_SIZE-8(%rsp) + movq %rax, MCOUNT_REG_SIZE(%rsp) + + restore_mcount_regs 8 + /* Restore flags */ + popfq +SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) + UNWIND_HINT_RET_OFFSET + jmp ftrace_epilogue + SYM_FUNC_END(ftrace_regs_caller) -- 2.26.1