From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:33526 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965131AbeGAQYk (ORCPT ); Sun, 1 Jul 2018 12:24:40 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Matthias Schiffer , Matt Redfearn , Paul Burton Subject: [PATCH 4.9 017/101] mips: ftrace: fix static function graph tracing Date: Sun, 1 Jul 2018 18:21:03 +0200 Message-Id: <20180701160757.823536881@linuxfoundation.org> In-Reply-To: <20180701160757.138608453@linuxfoundation.org> References: <20180701160757.138608453@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Matthias Schiffer commit 6fb8656646f996d1eef42e6d56203c4915cb9e08 upstream. ftrace_graph_caller was never run after calling ftrace_trace_function, breaking the function graph tracer. Fix this, bringing it in line with the x86 implementation. While we're at it, also streamline the control flow of _mcount a bit to reduce the number of branches. This issue was reported before: https://www.linux-mips.org/archives/linux-mips/2014-11/msg00295.html Signed-off-by: Matthias Schiffer Tested-by: Matt Redfearn Patchwork: https://patchwork.linux-mips.org/patch/18929/ Signed-off-by: Paul Burton Cc: stable@vger.kernel.org # v3.17+ Signed-off-by: Greg Kroah-Hartman --- arch/mips/kernel/mcount.S | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) --- a/arch/mips/kernel/mcount.S +++ b/arch/mips/kernel/mcount.S @@ -116,10 +116,20 @@ ftrace_stub: NESTED(_mcount, PT_SIZE, ra) PTR_LA t1, ftrace_stub PTR_L t2, ftrace_trace_function /* Prepare t2 for (1) */ - bne t1, t2, static_trace + beq t1, t2, fgraph_trace nop + MCOUNT_SAVE_REGS + + move a0, ra /* arg1: self return address */ + jalr t2 /* (1) call *ftrace_trace_function */ + move a1, AT /* arg2: parent's return address */ + + MCOUNT_RESTORE_REGS + +fgraph_trace: #ifdef CONFIG_FUNCTION_GRAPH_TRACER + PTR_LA t1, ftrace_stub PTR_L t3, ftrace_graph_return bne t1, t3, ftrace_graph_caller nop @@ -128,24 +138,11 @@ NESTED(_mcount, PT_SIZE, ra) bne t1, t3, ftrace_graph_caller nop #endif - b ftrace_stub -#ifdef CONFIG_32BIT - addiu sp, sp, 8 -#else - nop -#endif - -static_trace: - MCOUNT_SAVE_REGS - - move a0, ra /* arg1: self return address */ - jalr t2 /* (1) call *ftrace_trace_function */ - move a1, AT /* arg2: parent's return address */ - MCOUNT_RESTORE_REGS #ifdef CONFIG_32BIT addiu sp, sp, 8 #endif + .globl ftrace_stub ftrace_stub: RETURN_BACK