Hi Arnaldo, Here is the patch which fixes perf probe to find variable location correctly, on the recent dwarf format. This is not related to the SEGV issue which I fixed in previous mail.
Thank you, (2014/05/29 21:19), Masami Hiramatsu wrote: > Fix perf probe to find correct variable DIE which has location or > external instance by tracking down the lexical blocks. > > Current die_find_variable() expects that the all variable DIEs > which has DW_TAG_variable have a location. However, since recent > dwarf information may have declaration variable DIEs at the > entry of function (subprogram), die_find_variable() returns it. > > To solve this problem, it must track down the DIE tree to find > a DIE which has an actual location or a reference for external > instance. > > e.g. finding a DIE which origin is <0xdc73>; > > <1><11496>: Abbrev Number: 95 (DW_TAG_subprogram) > <11497> DW_AT_abstract_origin: <0xdc42> > <1149b> DW_AT_low_pc : 0x1850 > [...] > <2><114cc>: Abbrev Number: 119 (DW_TAG_variable) <- this is a declaration > <114cd> DW_AT_abstract_origin: <0xdc73> > <2><114d1>: Abbrev Number: 119 (DW_TAG_variable) > [...] > <3><115a7>: Abbrev Number: 105 (DW_TAG_lexical_block) > <115a8> DW_AT_ranges : 0xaa0 > <4><115ac>: Abbrev Number: 96 (DW_TAG_variable) <- this has a location > <115ad> DW_AT_abstract_origin: <0xdc73> > <115b1> DW_AT_location : 0x486c (location list) > > Signed-off-by: Masami Hiramatsu <[email protected]> > Cc: Arnaldo Carvalho de Melo <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Paul Mackerras <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Namhyung Kim <[email protected]> > Cc: Jiri Olsa <[email protected]> > --- > tools/perf/util/dwarf-aux.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c > index 7defd77..cc66c40 100644 > --- a/tools/perf/util/dwarf-aux.c > +++ b/tools/perf/util/dwarf-aux.c > @@ -747,14 +747,17 @@ struct __find_variable_param { > static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data) > { > struct __find_variable_param *fvp = data; > + Dwarf_Attribute attr; > int tag; > > tag = dwarf_tag(die_mem); > if ((tag == DW_TAG_formal_parameter || > tag == DW_TAG_variable) && > - die_compare_name(die_mem, fvp->name)) > + die_compare_name(die_mem, fvp->name) && > + /* Does the DIE have location information or external instance? */ > + (dwarf_attr(die_mem, DW_AT_external, &attr) || > + dwarf_attr(die_mem, DW_AT_location, &attr))) > return DIE_FIND_CB_END; > - > if (dwarf_haspc(die_mem, fvp->addr)) > return DIE_FIND_CB_CONTINUE; > else > > > > -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: [email protected] -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
