From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steven Rostedt Subject: [for-next][PATCH 17/18] function_graph: Reverse the order of pushing the ret_stack and the callback Date: Wed, 21 Nov 2018 19:28:18 -0500 Message-ID: <20181122003333.880108256@goodmis.org> References: <20181122002801.501220343@goodmis.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Return-path: Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Linus Torvalds , Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , linux-arch@vger.kernel.org, Joel Fernandes , Masami Hiramatsu , Josh Poimboeuf , Andy Lutomirski , Frederic Weisbecker , stable@kernel.org List-Id: linux-arch.vger.kernel.org From: "Steven Rostedt (VMware)" The function graph profiler uses the ret_stack to store the "subtime" and reuse it by nested functions and also on the return. But the current logic has the profiler callback called before the ret_stack is updated, and it is just modifying the ret_stack that will later be allocated (it's just lucky that the "subtime" is not touched when it is allocated). This could also cause a crash if we are at the end of the ret_stack when this happens. By reversing the order of the allocating the ret_stack and then calling the callbacks attached to a function being traced, the ret_stack entry is no longer used before it is allocated. Cc: stable@kernel.org Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback") Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_functions_graph.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 4f0d72ae6362..2561460d7baf 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -188,15 +188,17 @@ int function_graph_enter(unsigned long ret, unsigned long func, trace.func = func; trace.depth = ++current->curr_ret_depth; - /* Only trace if the calling function expects to */ - if (!ftrace_graph_entry(&trace)) - goto out; - if (ftrace_push_return_trace(ret, func, frame_pointer, retp)) goto out; + /* Only trace if the calling function expects to */ + if (!ftrace_graph_entry(&trace)) + goto out_ret; + return 0; + out_ret: + current->curr_ret_stack--; out: current->curr_ret_depth--; return -EBUSY; -- 2.19.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:48058 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390895AbeKVLKU (ORCPT ); Thu, 22 Nov 2018 06:10:20 -0500 Message-ID: <20181122003333.880108256@goodmis.org> Date: Wed, 21 Nov 2018 19:28:18 -0500 From: Steven Rostedt Subject: [for-next][PATCH 17/18] function_graph: Reverse the order of pushing the ret_stack and the callback References: <20181122002801.501220343@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-arch-owner@vger.kernel.org List-ID: To: linux-kernel@vger.kernel.org Cc: Linus Torvalds , Ingo Molnar , Andrew Morton , Thomas Gleixner , Peter Zijlstra , linux-arch@vger.kernel.org, Joel Fernandes , Masami Hiramatsu , Josh Poimboeuf , Andy Lutomirski , Frederic Weisbecker , stable@kernel.org Message-ID: <20181122002818.jjpSF2BJTO-OFa_eflIij4V5w4efgYuRKvPtURLUXzM@z> From: "Steven Rostedt (VMware)" The function graph profiler uses the ret_stack to store the "subtime" and reuse it by nested functions and also on the return. But the current logic has the profiler callback called before the ret_stack is updated, and it is just modifying the ret_stack that will later be allocated (it's just lucky that the "subtime" is not touched when it is allocated). This could also cause a crash if we are at the end of the ret_stack when this happens. By reversing the order of the allocating the ret_stack and then calling the callbacks attached to a function being traced, the ret_stack entry is no longer used before it is allocated. Cc: stable@kernel.org Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback") Signed-off-by: Steven Rostedt (VMware) --- kernel/trace/trace_functions_graph.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 4f0d72ae6362..2561460d7baf 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -188,15 +188,17 @@ int function_graph_enter(unsigned long ret, unsigned long func, trace.func = func; trace.depth = ++current->curr_ret_depth; - /* Only trace if the calling function expects to */ - if (!ftrace_graph_entry(&trace)) - goto out; - if (ftrace_push_return_trace(ret, func, frame_pointer, retp)) goto out; + /* Only trace if the calling function expects to */ + if (!ftrace_graph_entry(&trace)) + goto out_ret; + return 0; + out_ret: + current->curr_ret_stack--; out: current->curr_ret_depth--; return -EBUSY; -- 2.19.1