Commit 082f96a93eb5ba9bf771518a0dda590624568e8e
Committed by
Jiri Olsa
Jiri Olsa
1 parent
0c188a07b6
Exists in
ti-lsk-linux-4.1.y
and in
12 other branches
perf probe: Fix perf probe to find correct variable DIE
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 <masami.hiramatsu.pt@hitachi.com>
Tested-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Acked-by: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20140529121930.30879.87092.stgit@ltc230.yrl.intra.hitachi.co.jp
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Showing 1 changed file with 5 additions and 2 deletions Side-by-side Diff
tools/perf/util/dwarf-aux.c
| ... | ... | @@ -747,14 +747,17 @@ |
| 747 | 747 | static int __die_find_variable_cb(Dwarf_Die *die_mem, void *data) |
| 748 | 748 | { |
| 749 | 749 | struct __find_variable_param *fvp = data; |
| 750 | + Dwarf_Attribute attr; | |
| 750 | 751 | int tag; |
| 751 | 752 | |
| 752 | 753 | tag = dwarf_tag(die_mem); |
| 753 | 754 | if ((tag == DW_TAG_formal_parameter || |
| 754 | 755 | tag == DW_TAG_variable) && |
| 755 | - die_compare_name(die_mem, fvp->name)) | |
| 756 | + die_compare_name(die_mem, fvp->name) && | |
| 757 | + /* Does the DIE have location information or external instance? */ | |
| 758 | + (dwarf_attr(die_mem, DW_AT_external, &attr) || | |
| 759 | + dwarf_attr(die_mem, DW_AT_location, &attr))) | |
| 756 | 760 | return DIE_FIND_CB_END; |
| 757 | - | |
| 758 | 761 | if (dwarf_haspc(die_mem, fvp->addr)) |
| 759 | 762 | return DIE_FIND_CB_CONTINUE; |
| 760 | 763 | else |