Messages in this thread Patch in this message | | | From | Song Liu <> | Subject | [PATCH 1/2] perf util: move bperf definitions to a libperf header | Date | Fri, 2 Apr 2021 17:29:37 -0700 |
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By following the same protocol, other tools can share hardware PMCs with perf. Move perf_event_attr_map_entry and BPERF_DEFAULT_ATTR_MAP_PATH to bperf.h for other tools to use.
Also add bperf_attr_map_compatible() to check whether existing attr_map is compatible with current perf binary.
Signed-off-by: Song Liu <song@kernel.org> --- tools/lib/perf/include/perf/bperf.h | 29 +++++++++++++++++++ tools/perf/util/bpf_counter.c | 44 ++++++++++++++--------------- 2 files changed, 50 insertions(+), 23 deletions(-) create mode 100644 tools/lib/perf/include/perf/bperf.h
diff --git a/tools/lib/perf/include/perf/bperf.h b/tools/lib/perf/include/perf/bperf.h new file mode 100644 index 0000000000000..02b2fd5e50c75 --- /dev/null +++ b/tools/lib/perf/include/perf/bperf.h @@ -0,0 +1,29 @@ +/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ +#ifndef __LIBPERF_BPERF_H +#define __LIBPERF_BPERF_H + +/* + * bperf uses a hashmap, the attr_map, to track all the leader programs. + * The hashmap is pinned in bpffs. flock() on this file is used to ensure + * no concurrent access to the attr_map. The key of attr_map is struct + * perf_event_attr, and the value is struct perf_event_attr_map_entry. + * + * struct perf_event_attr_map_entry contains two __u32 IDs, bpf_link of the + * leader prog, and the diff_map. Each perf-stat session holds a reference + * to the bpf_link to make sure the leader prog is attached to sched_switch + * tracepoint. + * + * Since the hashmap only contains IDs of the bpf_link and diff_map, it + * does not hold any references to the leader program. Once all perf-stat + * sessions of these events exit, the leader prog, its maps, and the + * perf_events will be freed. + */ +struct perf_event_attr_map_entry { + __u32 link_id; + __u32 diff_map_id; +}; + +/* pin the map at sysfs__mountpoint()/BPERF_DEFAULT_ATTR_MAP_PATH */ +#define BPERF_DEFAULT_ATTR_MAP_PATH "fs/bpf/perf_attr_map" + +#endif /* __LIBPERF_BPERF_H */ diff --git a/tools/perf/util/bpf_counter.c b/tools/perf/util/bpf_counter.c index 81d1df3c4ec0e..df70c8dcf7850 100644 --- a/tools/perf/util/bpf_counter.c +++ b/tools/perf/util/bpf_counter.c @@ -14,6 +14,7 @@ #include <bpf/btf.h> #include <bpf/libbpf.h> #include <api/fs/fs.h> +#include <perf/bperf.h> #include "bpf_counter.h" #include "counts.h" @@ -29,28 +30,6 @@ #include "bpf_skel/bperf_leader.skel.h" #include "bpf_skel/bperf_follower.skel.h" -/* - * bperf uses a hashmap, the attr_map, to track all the leader programs. - * The hashmap is pinned in bpffs. flock() on this file is used to ensure - * no concurrent access to the attr_map. The key of attr_map is struct - * perf_event_attr, and the value is struct perf_event_attr_map_entry. - * - * struct perf_event_attr_map_entry contains two __u32 IDs, bpf_link of the - * leader prog, and the diff_map. Each perf-stat session holds a reference - * to the bpf_link to make sure the leader prog is attached to sched_switch - * tracepoint. - * - * Since the hashmap only contains IDs of the bpf_link and diff_map, it - * does not hold any references to the leader program. Once all perf-stat - * sessions of these events exit, the leader prog, its maps, and the - * perf_events will be freed. - */ -struct perf_event_attr_map_entry { - __u32 link_id; - __u32 diff_map_id; -}; - -#define DEFAULT_ATTR_MAP_PATH "fs/bpf/perf_attr_map" #define ATTR_MAP_SIZE 16 static inline void *u64_to_ptr(__u64 ptr) @@ -333,6 +312,20 @@ static __u32 bpf_map_get_id(int fd) return map_info.id; } +static bool bperf_attr_map_compatible(int attr_map_fd) +{ + struct bpf_map_info map_info = {0}; + __u32 map_info_len = sizeof(map_info); + int err; + + err = bpf_obj_get_info_by_fd(attr_map_fd, &map_info, &map_info_len); + + if (err) + return false; + return (map_info.key_size == sizeof(struct perf_event_attr)) && + (map_info.value_size == sizeof(struct perf_event_attr_map_entry)); +} + static int bperf_lock_attr_map(struct target *target) { char path[PATH_MAX]; @@ -342,7 +335,7 @@ static int bperf_lock_attr_map(struct target *target) scnprintf(path, PATH_MAX, "%s", target->attr_map); } else { scnprintf(path, PATH_MAX, "%s/%s", sysfs__mountpoint(), - DEFAULT_ATTR_MAP_PATH); + BPERF_DEFAULT_ATTR_MAP_PATH); } if (access(path, F_OK)) { @@ -367,6 +360,11 @@ static int bperf_lock_attr_map(struct target *target) return -1; } + if (!bperf_attr_map_compatible(map_fd)) { + close(map_fd); + return -1; + + } err = flock(map_fd, LOCK_EX); if (err) { close(map_fd); -- 2.30.2
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