From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: Re: [PATCH v3 1/6] perf: prepare perf_event.h for new types perf_kprobe and perf_uprobe Date: Mon, 4 Dec 2017 10:26:53 -0800 Message-ID: References: <20171130235023.1414663-1-songliubraving@fb.com> <20171130235023.1414663-4-songliubraving@fb.com> <20171203170312.rvjo6ifl2pgpjkcs@ast-mbp> Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Cc: Peter Zijlstra , Steven Rostedt , "mingo@redhat.com" , David Miller , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "daniel@iogearbox.net" , Kernel Team To: Song Liu , Alexei Starovoitov Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:58018 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752412AbdLDS1w (ORCPT ); Mon, 4 Dec 2017 13:27:52 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On 12/4/17 10:24 AM, Song Liu wrote: > >> On Dec 3, 2017, at 9:03 AM, Alexei Starovoitov wrote: >> >> On Thu, Nov 30, 2017 at 03:50:18PM -0800, Song Liu wrote: >>> Two new perf types, perf_kprobe and perf_uprobe, will be added to allow >>> creating [k,u]probe with perf_event_open. These [k,u]probe are associated >>> with the file decriptor created by perf_event_open, thus are easy to >>> clean when the file descriptor is destroyed. >>> >>> kprobe_func and uprobe_path are added to union config1 for pointers to >>> function name for kprobe or binary path for uprobe. >>> >>> kprobe_addr and probe_offset are added to union config2 for kernel >>> address (when kprobe_func is NULL), or [k,u]probe offset. >>> >>> Signed-off-by: Song Liu >>> Reviewed-by: Yonghong Song >>> Reviewed-by: Josef Bacik >>> Acked-by: Alexei Starovoitov >>> --- >>> include/uapi/linux/perf_event.h | 6 ++++++ >>> 1 file changed, 6 insertions(+) >>> >>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h >>> index 362493a..247c6cb 100644 >>> --- a/include/uapi/linux/perf_event.h >>> +++ b/include/uapi/linux/perf_event.h >>> @@ -299,6 +299,8 @@ enum perf_event_read_format { >>> #define PERF_ATTR_SIZE_VER4 104 /* add: sample_regs_intr */ >>> #define PERF_ATTR_SIZE_VER5 112 /* add: aux_watermark */ >>> >>> +#define MAX_PROBE_FUNC_NAME_LEN 64 >> >> I think we have to remove this restriction. >> There are already functions with names longer than 64 characters >> in the current vmlinux: >> trace_event_define_fields_ext4_ext_convert_to_initialized_fastpath >> trace_event_define_fields_mm_vmscan_direct_reclaim_begin_template >> >> How about we drop this restriction and use NAME_MAX internally >> without adding new uapi defines ? > > Yeah, I agree that we should drop this uapi define. How about we use > > #define KSYM_NAME_LEN 128 > > If a function name is longer than KSYM_NAME_LEN, we get warning like: > > Symbol long_long_name_abcdefghijklmnopqrstuvwxyz_abcdefghijklmnopqrstuvwxyz_abcdefghijklmnopqrstuvwxyz_abcdefghijklmnopqrstuvwxyz_abcdefghijklmnopqrstuvwxyz_abcdefghijklmnopqrstuvwxyz_abcdefghijklmnopqrstuvwxyz_ too long for kallsyms (204 vs 128). > Please increase KSYM_NAME_LEN both in kernel and kallsyms.c right. that's better. Thanks