Arnaldo Carvalho de Melo 8d06367fa7 perf symbols: Use the buildids if present
With this change 'perf record' will intercept PERF_RECORD_MMAP
calls, creating a linked list of DSOs, then when the session
finishes, it will traverse this list and read the buildids,
stashing them at the end of the file and will set up a new
feature bit in the header bitmask.

'perf report' will then notice this feature and populate the
'dsos' list and set the build ids.

When reading the symtabs it will refuse to load from a file that
doesn't have the same build id. This improves the
reliability of the profiler output, as symbols and profiling
data is more guaranteed to match.

Example:

 [root@doppio ~]# perf report | head
 /home/acme/bin/perf with build id b1ea544ac3746e7538972548a09aadecc5753868 not found, continuing without symbols
  # Samples: 2621434559
  #
  # Overhead          Command                  Shared Object  Symbol
  # ........  ...............  .............................  ......
  #
       7.91%             init  [kernel]        [k] read_hpet
       7.64%             init  [kernel]        [k] mwait_idle_with_hints
       7.60%          swapper  [kernel]        [k] read_hpet
       7.60%          swapper  [kernel]        [k] mwait_idle_with_hints
       3.65%             init  [kernel]        [k] 0xffffffffa02339d9
[root@doppio ~]#

In this case the 'perf' binary was an older one, vanished,
so its symbols probably wouldn't match or would cause subtly
different (and misleading) output.

Next patches will support the kernel as well, reading the build
id notes for it and the modules from /sys.

Another patch should also introduce a new plumbing command:

'perf list-buildids'

that will then be used in porcelain that is distro specific to
fetch -debuginfo packages where such buildids are present. This
will in turn allow for one to run 'perf record' in one machine
and 'perf report' in another.

Future work on having the buildid sent directly from the kernel
in the PERF_RECORD_MMAP event is needed to close races, as the
DSO can be changed during a 'perf record' session, but this
patch at least helps with non-corner cases and current/older
kernels.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: K. Prasad <prasad@linux.vnet.ibm.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1257367843-26224-1-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-11-08 10:44:36 +01:00

127 lines
2.5 KiB
C

#ifndef __PERF_RECORD_H
#define __PERF_RECORD_H
#include "../perf.h"
#include "util.h"
#include <linux/list.h>
#include <linux/rbtree.h>
/*
* PERF_SAMPLE_IP | PERF_SAMPLE_TID | *
*/
struct ip_event {
struct perf_event_header header;
u64 ip;
u32 pid, tid;
unsigned char __more_data[];
};
struct mmap_event {
struct perf_event_header header;
u32 pid, tid;
u64 start;
u64 len;
u64 pgoff;
char filename[PATH_MAX];
};
struct comm_event {
struct perf_event_header header;
u32 pid, tid;
char comm[16];
};
struct fork_event {
struct perf_event_header header;
u32 pid, ppid;
u32 tid, ptid;
u64 time;
};
struct lost_event {
struct perf_event_header header;
u64 id;
u64 lost;
};
/*
* PERF_FORMAT_ENABLED | PERF_FORMAT_RUNNING | PERF_FORMAT_ID
*/
struct read_event {
struct perf_event_header header;
u32 pid, tid;
u64 value;
u64 time_enabled;
u64 time_running;
u64 id;
};
struct sample_event{
struct perf_event_header header;
u64 array[];
};
#define BUILD_ID_SIZE 20
struct build_id_event {
struct perf_event_header header;
u8 build_id[ALIGN(BUILD_ID_SIZE, sizeof(u64))];
char filename[];
};
typedef union event_union {
struct perf_event_header header;
struct ip_event ip;
struct mmap_event mmap;
struct comm_event comm;
struct fork_event fork;
struct lost_event lost;
struct read_event read;
struct sample_event sample;
} event_t;
struct map {
union {
struct rb_node rb_node;
struct list_head node;
};
u64 start;
u64 end;
u64 pgoff;
u64 (*map_ip)(struct map *, u64);
u64 (*unmap_ip)(struct map *, u64);
struct dso *dso;
};
static inline u64 map__map_ip(struct map *map, u64 ip)
{
return ip - map->start + map->pgoff;
}
static inline u64 map__unmap_ip(struct map *map, u64 ip)
{
return ip + map->start - map->pgoff;
}
static inline u64 identity__map_ip(struct map *map __used, u64 ip)
{
return ip;
}
struct symbol;
typedef int (*symbol_filter_t)(struct map *map, struct symbol *sym);
void map__init(struct map *self, u64 start, u64 end, u64 pgoff,
struct dso *dso);
struct map *map__new(struct mmap_event *event, char *cwd, int cwdlen);
struct map *map__clone(struct map *self);
int map__overlap(struct map *l, struct map *r);
size_t map__fprintf(struct map *self, FILE *fp);
struct symbol *map__find_symbol(struct map *self, u64 ip, symbol_filter_t filter);
int event__synthesize_thread(pid_t pid, int (*process)(event_t *event));
void event__synthesize_threads(int (*process)(event_t *event));
#endif /* __PERF_RECORD_H */