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Mon, 15 Apr 2024 15:49:23 GMT Received: from pps.reinject (localhost [127.0.0.1]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 3xgkwdu249-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 15 Apr 2024 15:49:23 +0000 Received: from phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 43FFnMuT028510; Mon, 15 Apr 2024 15:49:23 GMT Received: from jfwang-mac.us.oracle.com (dhcp-10-65-136-194.vpn.oracle.com [10.65.136.194]) by phxpaimrmta03.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTP id 3xgkwdu238-2; Mon, 15 Apr 2024 15:49:23 +0000 From: Jianfeng Wang To: linux-trace-devel@vger.kernel.org Cc: rostedt@goodmis.org, jianfeng.w.wang@oracle.com Subject: [PATCH 1/2] trace-cmd ftrace: print function retval in function_graph Date: Mon, 15 Apr 2024 08:49:20 -0700 Message-ID: <20240415154921.4998-2-jianfeng.w.wang@oracle.com> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20240415154921.4998-1-jianfeng.w.wang@oracle.com> References: <20240415154921.4998-1-jianfeng.w.wang@oracle.com> Precedence: bulk X-Mailing-List: linux-trace-devel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-04-15_12,2024-04-15_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxscore=0 mlxlogscore=999 suspectscore=0 adultscore=0 phishscore=0 bulkscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2404010000 definitions=main-2404150103 X-Proofpoint-GUID: fNVWJAdlalrZd1u3p7-DNkikaCswzu1t X-Proofpoint-ORIG-GUID: fNVWJAdlalrZd1u3p7-DNkikaCswzu1t The upstream Linux kernel has introduced a new feature, i.e. funcgraph-retval for the function_graph tracer. (Commit ID: a1be9ccc57f07d54278be34eed6bd679bc941c97). With this feature, the function_graph tracer can record each function's return value along with its execution time at the function_graph exit handler. This is useful for debugging kernel issues, such as syscall errors. This commit enhances 'trace-cmd report' by supporting the function_graph retval feature if the underlying kernel supports it. Once the feature is supported, 'trace-cmd report' will print each function's return value in this format: '(ret=retval)" at the end of every funcgraph leaf entry and exit event. Signed-off-by: Jianfeng Wang --- lib/trace-cmd/trace-ftrace.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) diff --git a/lib/trace-cmd/trace-ftrace.c b/lib/trace-cmd/trace-ftrace.c index 89e46c3d..cb05d88c 100644 --- a/lib/trace-cmd/trace-ftrace.c +++ b/lib/trace-cmd/trace-ftrace.c @@ -185,6 +185,8 @@ print_graph_entry_leaf(struct trace_seq *s, unsigned long long rettime, calltime; unsigned long long duration, depth; unsigned long long val; + unsigned long long retval; + bool fgraph_retval_supported = true; const char *func; int ret; int i; @@ -195,6 +197,13 @@ print_graph_entry_leaf(struct trace_seq *s, if (tep_get_field_val(s, finfo->fgraph_ret_event, "calltime", ret_rec, &calltime, 1)) return trace_seq_putc(s, '!'); + if (!tep_find_field(finfo->fgraph_ret_event, "retval")) + fgraph_retval_supported = false; + else { + if (tep_get_field_val(s, finfo->fgraph_ret_event, "retval", ret_rec, &retval, 1)) + return trace_seq_putc(s, '!'); + } + duration = rettime - calltime; /* Overhead */ @@ -222,6 +231,10 @@ print_graph_entry_leaf(struct trace_seq *s, if (ret && fgraph_depth->set) ret = trace_seq_printf(s, " (%lld)", depth); + /* Return Value */ + if (ret && fgraph_retval_supported) + ret = trace_seq_printf(s, " (ret=%lld)", retval); + return ret; } @@ -316,6 +329,8 @@ fgraph_ret_handler(struct trace_seq *s, struct tep_record *record, unsigned long long duration, depth; unsigned long long val; const char *func; + unsigned long long retval; + bool fgraph_retval_supported = true; int i; ret_event_check(finfo, event->tep); @@ -326,6 +341,13 @@ fgraph_ret_handler(struct trace_seq *s, struct tep_record *record, if (tep_get_field_val(s, event, "calltime", record, &calltime, 1)) return trace_seq_putc(s, '!'); + if (!tep_find_field(event, "retval")) + fgraph_retval_supported = false; + else { + if (tep_get_field_val(s, event, "retval", record, &retval, 1)) + return trace_seq_putc(s, '!'); + } + duration = rettime - calltime; /* Overhead */ @@ -355,6 +377,10 @@ fgraph_ret_handler(struct trace_seq *s, struct tep_record *record, if (fgraph_depth->set) trace_seq_printf(s, " (%lld)", depth); + /* Return Value */ + if (fgraph_retval_supported) + trace_seq_printf(s, " (ret=%lld)", retval); + return 0; }