• He Kuang's avatar
    perf tools: Find right DSO taking into account if binary is 32 or 64-bit · 76c588f1
    He Kuang authored
    There's a problem in machine__findnew_vdso(), vdso buildid generated by a
    32-bit machine stores it with the name 'vdso', but when processing buildid on a
    64-bit machine with the same 'perf.data', perf will search for vdso named as
    'vdso32' and get failed.
    
    This patch tries to find the existing dsos in machine->dsos by thread dso_type.
    64-bit thread tries to find vdso with name 'vdso', because all 64-bit vdso is
    named as that. 32-bit thread first tries to find vdso with name 'vdso32' if
    this thread was run on 64-bit machine, if failed, then it tries 'vdso' which
    indicates that the thread was run on 32-bit machine when recording.
    
    Committer note:
    
    Additional explanation by Adrian Hunter:
    
    We match maps to builds ids using the file name - consider
    machine__findnew_[v]dso() called in map__new().  So in the context of a perf
    data file, we consider the file name to be unique.
    
    A vdso map does not have a file name - all we know is that it is vdso.  We look
    at the thread to tell if it is 32-bit, 64-bit or x32.  Then we need to get the
    build id which has been recorded using short name "[vdso]" or "[vdso32]" or
    "[vdsox32]".
    
    The problem is that on a 32-bit machine, we use the name "[vdso]".  If you take
    a 32-bit perf data file to a 64-bit machine, it gets hard to figure out if
    "[vdso]" is 32-bit or 64-bit.
    
    This patch solves that problem.
    
     ----
    
    This also merges a followup patch fixing a problem introduced by the
    original submission of this patch, that would crash 'perf record' when
    recording samples for a 32-bit app on a 64-bit system.
    Signed-off-by: default avatarHe Kuang <hekuang@huawei.com>
    Acked-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
    Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: David Ahern <dsahern@gmail.com>
    Cc: Ekaterina Tumanova <tumanova@linux.vnet.ibm.com>
    Cc: Jiri Olsa <jolsa@redhat.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Kan Liang <kan.liang@intel.com>
    Cc: Masami Hiramatsu <mhiramat@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Pekka Enberg <penberg@kernel.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephane Eranian <eranian@google.com>
    Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
    Cc: Wang Nan <wangnan0@huawei.com>
    Link: http://lkml.kernel.org/r/1463475894-163531-1-git-send-email-hekuang@huawei.com
    Link: http://lkml.kernel.org/r/1466578626-92406-6-git-send-email-hekuang@huawei.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    76c588f1
vdso.c 7.08 KB