Messages in this thread | | | From | Song Liu <> | Subject | Re: [PATCH v3 1/6] perf: prepare perf_event.h for new types perf_kprobe and perf_uprobe | Date | Mon, 4 Dec 2017 18:24:59 +0000 |
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> On Dec 3, 2017, at 9:03 AM, Alexei Starovoitov <alexei.starovoitov@gmail.com> 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 <songliubraving@fb.com> >> Reviewed-by: Yonghong Song <yhs@fb.com> >> Reviewed-by: Josef Bacik <jbacik@fb.com> >> Acked-by: Alexei Starovoitov <ast@kernel.org> >> --- >> 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
Thanks, Song
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