lkml.org 
[lkml]   [2010]   [Jan]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5/6] perf top: fix annotate for userspace
    Date
    First, for programs and prelinked libraries, annotate code was fooled by
    objdump output IPs (src->eip in the code) being wrongly converted to
    absolute IPs. In such case there were no conversion needed, but in

    src->eip = strtoull(src->line, NULL, 16);
    src->eip = map->unmap_ip(map, src->eip); // = eip + map->start - map->pgoff

    we were reading absolute address from objdump (e.g. 8048604) and then
    almost doubling it, because eip & map->start are approximately close for
    small programs.

    Needless to say, that later, in record_precise_ip() there was no
    matching with real runtime IPs.

    And second, like with `perf annotate` the problem with non-prelinked
    *.so was that we were doing rip -> objdump address conversion wrong.

    Also, because unlike `perf annotate`, `perf top` code does annotation based on
    absolute IPs for performance reasons(*), new helper for mapping objdump
    addresse to IP is introduced.

    (*) we get samples info in absolute IPs, and since we do lots of
    hit-testing on absolute IPs at runtime in record_precise_ip(), it's
    better to convert objdump addresses to IPs once and do no conversion
    at runtime.

    I also had to fix how objdump output is parsed (with hardcoded 8/16
    characters format, which was inappropriate for ET_DYN dsos with small
    addresses like '4ac')

    Also note, that not all objdump output lines has associtated IPs, e.g.
    look at source lines here:

    000004ac <my_strlen>:
    extern "C"
    int my_strlen(const char *s)
    4ac: 55 push %ebp
    4ad: 89 e5 mov %esp,%ebp
    4af: 83 ec 10 sub $0x10,%esp
    {
    int len = 0;
    4b2: c7 45 fc 00 00 00 00 movl $0x0,-0x4(%ebp)
    4b9: eb 08 jmp 4c3 <my_strlen+0x17>

    while (*s) {
    ++len;
    4bb: 83 45 fc 01 addl $0x1,-0x4(%ebp)
    ++s;
    4bf: 83 45 08 01 addl $0x1,0x8(%ebp)

    So we mark them with eip=0, and ignore such lines in annotate lookup
    code.

    Signed-off-by: Kirill Smelkov <kirr@landau.phys.spbu.ru>
    Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Mike Galbraith <efault@gmx.de>
    ---
    tools/perf/builtin-top.c | 24 ++++++++++++++----------
    tools/perf/util/map.c | 8 ++++++++
    tools/perf/util/map.h | 3 ++-
    3 files changed, 24 insertions(+), 11 deletions(-)

    diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
    index 4067e4d..6aa9b02 100644
    --- a/tools/perf/builtin-top.c
    +++ b/tools/perf/builtin-top.c
    @@ -176,6 +176,7 @@ static void parse_source(struct sym_entry *syme)
    FILE *file;
    char command[PATH_MAX*2];
    const char *path;
    + char *tmp;
    u64 len;

    if (!syme)
    @@ -204,8 +205,8 @@ static void parse_source(struct sym_entry *syme)
    sprintf(command,
    "objdump --start-address=0x%016Lx "
    "--stop-address=0x%016Lx -dS %s",
    - map->unmap_ip(map, sym->start),
    - map->unmap_ip(map, sym->end), path);
    + map__rip_2objdump(map, sym->start),
    + map__rip_2objdump(map, sym->end), path);

    file = popen(command, "r");
    if (!file)
    @@ -235,14 +236,13 @@ static void parse_source(struct sym_entry *syme)
    *source->lines_tail = src;
    source->lines_tail = &src->next;

    - if (strlen(src->line)>8 && src->line[8] == ':') {
    - src->eip = strtoull(src->line, NULL, 16);
    - src->eip = map->unmap_ip(map, src->eip);
    - }
    - if (strlen(src->line)>8 && src->line[16] == ':') {
    - src->eip = strtoull(src->line, NULL, 16);
    - src->eip = map->unmap_ip(map, src->eip);
    - }
    +
    + src->eip = strtoull(src->line, &tmp, 16);
    + if (*tmp == ':')
    + src->eip = map__objdump_2ip(map, src->eip);
    + else
    + /* this line has no ip info (e.g. source line) */
    + src->eip = 0;
    }
    pclose(file);
    out_assign:
    @@ -277,6 +277,10 @@ static void record_precise_ip(struct sym_entry *syme, int counter, u64 ip)
    goto out_unlock;

    for (line = syme->src->lines; line; line = line->next) {
    + /* skip lines without IP info */
    + if (line->eip == 0)
    + continue;
    +
    if (line->eip == ip) {
    line->count[counter]++;
    break;
    diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
    index d6da969..37bfcc5 100644
    --- a/tools/perf/util/map.c
    +++ b/tools/perf/util/map.c
    @@ -215,3 +215,11 @@ u64 map__rip_2objdump(struct map *map, u64 rip)
    rip;
    return addr;
    }
    +
    +u64 map__objdump_2ip(struct map *map, u64 addr)
    +{
    + u64 ip = map->dso->adjust_symbols ?
    + addr :
    + map->unmap_ip(map, addr); /* RIP -> IP */
    + return ip;
    +}
    diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
    index 39fa478..2bcd9d4 100644
    --- a/tools/perf/util/map.h
    +++ b/tools/perf/util/map.h
    @@ -49,8 +49,9 @@ static inline u64 identity__map_ip(struct map *map __used, u64 ip)
    }


    -/* rip -> addr suitable for passing to `objdump --start-address=` */
    +/* rip/ip <-> addr suitable for passing to `objdump --start-address=` */
    u64 map__rip_2objdump(struct map *map, u64 rip);
    +u64 map__objdump_2ip(struct map *map, u64 addr);


    struct symbol;
    --
    1.6.6.79.gd514e.dirty

    \
     
     \ /
      Last update: 2010-01-08 13:53    [W:0.034 / U:61.868 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site