On Sat, Jun 24, 2023 at 12:49 AM Quentin Monnet <quentin@xxxxxxxxxxxxx> wrote:
>
> 2023-06-23 14:15 UTC+0000 ~ Yafang Shao <laoar.shao@xxxxxxxxx>
> > Enhance bpftool to display comprehensive information about exposed
> > perf_event links, covering uprobe, kprobe, tracepoint, and generic perf
> > event. The resulting output will include the following details:
> >
> > $ tools/bpf/bpftool/bpftool link show
> > 4: perf_event prog 23
> > uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
> > bpf_cookie 0
> > pids uprobe(27503)
> > 5: perf_event prog 24
> > uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
> > bpf_cookie 0
> > pids uprobe(27503)
> > 6: perf_event prog 31
> > kprobe ffffffffa90a9660 kernel_clone
> > bpf_cookie 0
> > pids kprobe(27777)
> > 7: perf_event prog 30
> > kretprobe ffffffffa90a9660 kernel_clone
> > bpf_cookie 0
> > pids kprobe(27777)
> > 8: perf_event prog 37
> > tracepoint sched_switch
> > bpf_cookie 0
> > pids tracepoint(28036)
> > 9: perf_event prog 43
> > event software:cpu-clock
> > bpf_cookie 0
> > pids perf_event(28261)
> > 10: perf_event prog 43
> > event hw-cache:LLC-load-misses
> > bpf_cookie 0
> > pids perf_event(28261)
> > 11: perf_event prog 43
> > event hardware:cpu-cycles
> > bpf_cookie 0
> > pids perf_event(28261)
> >
> > $ tools/bpf/bpftool/bpftool link show -j
> > [{"id":4,"type":"perf_event","prog_id":23,"retprobe":false,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":27503,"comm":"uprobe"}]},{"id":5,"type":"perf_event","prog_id":24,"retprobe":true,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":27503,"comm":"uprobe"}]},{"id":6,"type":"perf_event","prog_id":31,"retprobe":false,"addr":18446744072250627680,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":27777,"comm":"kprobe"}]},{"id":7,"type":"perf_event","prog_id":30,"retprobe":true,"addr":18446744072250627680,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":27777,"comm":"kprobe"}]},{"id":8,"type":"perf_event","prog_id":37,"tracepoint":"sched_switch","bpf_cookie":0,"pids":[{"pid":28036,"comm":"tracepoint"}]},{"id":9,"type":"perf_event","prog_id":43,"event_type":"software","event_config":"cpu-clock","bpf_cookie":0,"pids":[{"pid":28261,"comm":"perf_event"}]},{"id":10,"type":"perf_event","prog_id":43,"event_type":"hw-cache","event_config":"LLC-load-misses","bpf_cookie":0,"pids":[{"pid":28261,"comm":"perf_event"}]},{"id":11,"type":"perf_event","prog_id":43,"event_type":"hardware","event_config":"cpu-cycles","bpf_cookie":0,"pids":[{"pid":28261,"comm":"perf_event"}]}]
> >
> > For generic perf events, the displayed information in bpftool is limited to
> > the type and configuration, while other attributes such as sample_period,
> > sample_freq, etc., are not included.
> >
> > The kernel function address won't be exposed if it is not permitted by
> > kptr_restrict. The result as follows when kptr_restrict is 2.
> >
> > $ tools/bpf/bpftool/bpftool link show
> > 4: perf_event prog 23
> > uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
> > 5: perf_event prog 24
> > uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
> > 6: perf_event prog 31
> > kprobe kernel_clone
> > 7: perf_event prog 30
> > kretprobe kernel_clone
> > 8: perf_event prog 37
> > tracepoint sched_switch
> > 9: perf_event prog 43
> > event software:cpu-clock
> > 10: perf_event prog 43
> > event hw-cache:LLC-load-misses
> > 11: perf_event prog 43
> > event hardware:cpu-cycles
> >
> > Signed-off-by: Yafang Shao <laoar.shao@xxxxxxxxx>
> > ---
> > tools/bpf/bpftool/link.c | 237 ++++++++++++++++++++++++++++++++++++++++++++++-
> > 1 file changed, 236 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/bpf/bpftool/link.c b/tools/bpf/bpftool/link.c
> > index e5aeee3..31bee95 100644
> > --- a/tools/bpf/bpftool/link.c
> > +++ b/tools/bpf/bpftool/link.c
> > @@ -17,6 +17,8 @@
> > #include "main.h"
> > #include "xlated_dumper.h"
> >
> > +#define PERF_HW_CACHE_LEN 128
> > +
> > static struct hashmap *link_table;
> > static struct dump_data dd = {};
> >
> > @@ -274,6 +276,110 @@ static int cmp_u64(const void *A, const void *B)
> > jsonw_end_array(json_wtr);
> > }
> >
> > +static void
> > +show_perf_event_kprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
> > +{
> > + jsonw_bool_field(wtr, "retprobe", info->perf_event.kprobe.flags & 0x1);
> > + jsonw_uint_field(wtr, "addr", info->perf_event.kprobe.addr);
> > + jsonw_string_field(wtr, "func",
> > + u64_to_ptr(info->perf_event.kprobe.func_name));
> > + jsonw_uint_field(wtr, "offset", info->perf_event.kprobe.offset);
> > +}
> > +
> > +static void
> > +show_perf_event_uprobe_json(struct bpf_link_info *info, json_writer_t *wtr)
> > +{
> > + jsonw_bool_field(wtr, "retprobe", info->perf_event.uprobe.flags & 0x1);
> > + jsonw_string_field(wtr, "file",
> > + u64_to_ptr(info->perf_event.uprobe.file_name));
> > + jsonw_uint_field(wtr, "offset", info->perf_event.uprobe.offset);
> > +}
> > +
> > +static void
> > +show_perf_event_tracepoint_json(struct bpf_link_info *info, json_writer_t *wtr)
> > +{
> > + jsonw_string_field(wtr, "tracepoint",
> > + u64_to_ptr(info->perf_event.tracepoint.tp_name));
> > +}
> > +
> > +static char *perf_config_hw_cache_str(__u64 config)
> > +{
> > + const char *hw_cache, *result, *op;
> > + char *str = malloc(PERF_HW_CACHE_LEN);
> > +
> > + if (!str) {
> > + p_err("mem alloc failed");
> > + return NULL;
> > + }
> > +
> > + hw_cache = perf_event_name(evsel__hw_cache, config & 0xff);
> > + if (hw_cache)
> > + snprintf(str, PERF_HW_CACHE_LEN, "%s-", hw_cache);
> > + else
> > + snprintf(str, PERF_HW_CACHE_LEN, "%lld-", config & 0xff);
> > +
> > + op = perf_event_name(evsel__hw_cache_op, (config >> 8) & 0xff);
> > + if (op)
> > + snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
> > + "%s-", op);
> > + else
> > + snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
> > + "%lld-", (config >> 8) & 0xff);
> > +
> > + result = perf_event_name(evsel__hw_cache_result, config >> 16);
> > + if (result)
> > + snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
> > + "%s", result);
> > + else
> > + snprintf(str + strlen(str), PERF_HW_CACHE_LEN - strlen(str),
> > + "%lld", config >> 16);
> > + return str;
> > +}
> > +
> > +static const char *perf_config_str(__u32 type, __u64 config)
> > +{
> > + const char *perf_config;
> > +
> > + switch (type) {
> > + case PERF_TYPE_HARDWARE:
> > + perf_config = perf_event_name(event_symbols_hw, config);
> > + break;
> > + case PERF_TYPE_SOFTWARE:
> > + perf_config = perf_event_name(event_symbols_sw, config);
> > + break;
> > + case PERF_TYPE_HW_CACHE:
> > + perf_config = perf_config_hw_cache_str(config);
> > + break;
> > + default:
> > + perf_config = NULL;
> > + break;
> > + }
> > + return perf_config;
> > +}
> > +
> > +static void
> > +show_perf_event_event_json(struct bpf_link_info *info, json_writer_t *wtr)
> > +{
> > + __u64 config = info->perf_event.event.config;
> > + __u32 type = info->perf_event.event.type;
> > + const char *perf_type, *perf_config;
> > +
> > + perf_type = perf_event_name(perf_type_name, type);
> > + if (perf_type)
> > + jsonw_string_field(wtr, "event_type", perf_type);
> > + else
> > + jsonw_uint_field(wtr, "event_type", type);
> > +
> > + perf_config = perf_config_str(type, config);
> > + if (perf_config)
> > + jsonw_string_field(wtr, "event_config", perf_config);
> > + else
> > + jsonw_uint_field(wtr, "event_config", config);
> > +
> > + if (type == PERF_TYPE_HW_CACHE && perf_config)
> > + free((void *)perf_config);
> > +}
> > +
> > static int show_link_close_json(int fd, struct bpf_link_info *info)
> > {
> > struct bpf_prog_info prog_info;
> > @@ -329,6 +435,24 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
> > case BPF_LINK_TYPE_KPROBE_MULTI:
> > show_kprobe_multi_json(info, json_wtr);
> > break;
> > + case BPF_LINK_TYPE_PERF_EVENT:
> > + switch (info->perf_event.type) {
> > + case BPF_PERF_EVENT_EVENT:
> > + show_perf_event_event_json(info, json_wtr);
> > + break;
> > + case BPF_PERF_EVENT_TRACEPOINT:
> > + show_perf_event_tracepoint_json(info, json_wtr);
> > + break;
> > + case BPF_PERF_EVENT_KPROBE:
> > + show_perf_event_kprobe_json(info, json_wtr);
> > + break;
> > + case BPF_PERF_EVENT_UPROBE:
> > + show_perf_event_uprobe_json(info, json_wtr);
> > + break;
> > + default:
> > + break;
> > + }
> > + break;
> > default:
> > break;
> > }
> > @@ -500,6 +624,75 @@ static void show_kprobe_multi_plain(struct bpf_link_info *info)
> > }
> > }
> >
> > +static void show_perf_event_kprobe_plain(struct bpf_link_info *info)
> > +{
> > + const char *buf;
> > +
> > + buf = (const char *)u64_to_ptr(info->perf_event.kprobe.func_name);
> > + if (buf[0] == '\0' && !info->perf_event.kprobe.addr)
> > + return;
> > +
> > + if (info->perf_event.kprobe.flags & 0x1)
> > + printf("\n\tkretprobe ");
> > + else
> > + printf("\n\tkprobe ");
> > + if (info->perf_event.kprobe.addr)
> > + printf("%llx ", info->perf_event.kprobe.addr);
> > + printf("%s", buf);
> > + if (info->perf_event.kprobe.offset)
> > + printf("+%#x", info->perf_event.kprobe.offset);
> > + printf(" ");
> > +}
> > +
> > +static void show_perf_event_uprobe_plain(struct bpf_link_info *info)
> > +{
> > + const char *buf;
> > +
> > + buf = (const char *)u64_to_ptr(info->perf_event.uprobe.file_name);
> > + if (buf[0] == '\0')
> > + return;
> > +
> > + if (info->perf_event.uprobe.flags & 0x1)
> > + printf("\n\turetprobe ");
> > + else
> > + printf("\n\tuprobe ");
> > + printf("%s+%#x ", buf, info->perf_event.uprobe.offset);
> > +}
> > +
> > +static void show_perf_event_tracepoint_plain(struct bpf_link_info *info)
> > +{
> > + const char *buf;
> > +
> > + buf = (const char *)u64_to_ptr(info->perf_event.tracepoint.tp_name);
> > + if (buf[0] == '\0')
> > + return;
> > +
> > + printf("\n\ttracepoint %s ", buf);
> > +}
> > +
> > +static void show_perf_event_event_plain(struct bpf_link_info *info)
> > +{
> > + __u64 config = info->perf_event.event.config;
> > + __u32 type = info->perf_event.event.type;
> > + const char *perf_type, *perf_config;
> > +
> > + printf("\n\tevent ");
> > + perf_type = perf_event_name(perf_type_name, type);
> > + if (perf_type)
> > + printf("%s:", perf_type);
> > + else
> > + printf("%u :", type);
> > +
> > + perf_config = perf_config_str(type, config);
> > + if (perf_config)
> > + printf("%s ", perf_config);
> > + else
> > + printf("%llu ", config);
> > +
> > + if (type == PERF_TYPE_HW_CACHE && perf_config)
> > + free((void *)perf_config);
> > +}
> > +
> > static int show_link_close_plain(int fd, struct bpf_link_info *info)
> > {
> > struct bpf_prog_info prog_info;
> > @@ -548,6 +741,24 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
> > case BPF_LINK_TYPE_KPROBE_MULTI:
> > show_kprobe_multi_plain(info);
> > break;
> > + case BPF_LINK_TYPE_PERF_EVENT:
> > + switch (info->perf_event.type) {
> > + case BPF_PERF_EVENT_EVENT:
> > + show_perf_event_event_plain(info);
> > + break;
> > + case BPF_PERF_EVENT_TRACEPOINT:
> > + show_perf_event_tracepoint_plain(info);
> > + break;
> > + case BPF_PERF_EVENT_KPROBE:
> > + show_perf_event_kprobe_plain(info);
> > + break;
> > + case BPF_PERF_EVENT_UPROBE:
> > + show_perf_event_uprobe_plain(info);
> > + break;
> > + default:
> > + break;
> > + }
> > + break;
> > default:
> > break;
> > }
> > @@ -570,11 +781,12 @@ static int do_show_link(int fd)
> > struct bpf_link_info info;
> > __u32 len = sizeof(info);
> > __u64 *addrs = NULL;
> > - char buf[256];
> > + char buf[PATH_MAX];
> > int count;
> > int err;
> >
> > memset(&info, 0, sizeof(info));
> > + buf[0] = '\0';
> > again:
> > err = bpf_link_get_info_by_fd(fd, &info, &len);
> > if (err) {
> > @@ -609,7 +821,30 @@ static int do_show_link(int fd)
> > goto again;
> > }
> > }
> > + if (info.type == BPF_LINK_TYPE_PERF_EVENT) {
> > + if (info.perf_event.type == BPF_PERF_EVENT_EVENT)
> > + goto out;
>
> This "if (...) goto out;" seems unnecessary? If info.perf_event.type is
> BPF_PERF_EVENT_EVENT we won't match any of the conditions below and
> should reach the "out:" label anyway (and that label seems also
> unnecessary)?
Makes sense. Will change it.
--
Regards
Yafang
