| Message ID | 20171130235023.1414663-4-songliubraving@fb.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [v3,1/6] perf: prepare perf_event.h for new types perf_kprobe and perf_uprobe | expand |
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 ?
> 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
On 12/4/17 10:24 AM, Song Liu wrote: > >> 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 right. that's better. Thanks
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 + /* * Hardware event_id to monitor via a performance monitoring event: * @@ -380,10 +382,14 @@ struct perf_event_attr { __u32 bp_type; union { __u64 bp_addr; + __u64 kprobe_func; /* for perf_kprobe */ + __u64 uprobe_path; /* for perf_uprobe */ __u64 config1; /* extension of config */ }; union { __u64 bp_len; + __u64 kprobe_addr; /* when kprobe_func == NULL */ + __u64 probe_offset; /* for perf_[k,u]probe */ __u64 config2; /* extension of config1 */ }; __u64 branch_sample_type; /* enum perf_branch_sample_type */