Messages in this thread Patch in this message | | | Date | Mon, 26 Mar 2012 15:22:07 +0530 | From | Prashanth Nageshappa <> | Subject | Re: [PATCH] perf - probe finder fails to resolve function name to address |
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On 03/23/2012 06:22 PM, Masami Hiramatsu wrote:
> Hi, > > (2012/03/22 19:23), Prashanth Nageshappa wrote: >> probe finder fails to resolve valid function names into addresses for >> functions which have more than one die entries in DWARF info. >> >> It is valid for DWARF info to contain more than 1 entries for a given >> function name, where one entry corresponds to definition which has code >> address/range attributes and remaining entries (which are only >> declarations) does not have code address/range attributes. >> (example: do_fork, sys_write, sys_wait4, sys_sync etc) > > Hmm, I'd like to reproduce and see what happened on debuginfo in those cases. > Could you tell me your environment or actual dwarf dump of those entries as below? >
$ uname -r 3.1.0-7.fc16.x86_64
$ sudo perf probe do_fork Failed to get entry address of do_fork. Error: Failed to add events. (-2)
$ readelf -wi /usr/lib/debug/lib/modules/3.1.0-7.fc16.x86_64/vmlinux | grep do_fork -A 16 <2691f7> DW_AT_name : (indirect string, offset: 0x1b1e0): do_fork <2691fb> DW_AT_decl_file : 3 <2691fc> DW_AT_decl_line : 2269 <2691fe> DW_AT_prototyped : 1 <2691fe> DW_AT_type : <0x2593d1> <269202> DW_AT_declaration : 1 <269202> DW_AT_sibling : <0x269225> <2><269206>: Abbrev Number: 14 (DW_TAG_formal_parameter) <269207> DW_AT_type : <0x259284> <2><26920b>: Abbrev Number: 14 (DW_TAG_formal_parameter) <26920c> DW_AT_type : <0x259284> <2><269210>: Abbrev Number: 14 (DW_TAG_formal_parameter) <269211> DW_AT_type : <0x25b2b1> <2><269215>: Abbrev Number: 14 (DW_TAG_formal_parameter) <269216> DW_AT_type : <0x259284> <2><26921a>: Abbrev Number: 14 (DW_TAG_formal_parameter) <26921b> DW_AT_type : <0x25a1f3> -- <4015fc> DW_AT_name : (indirect string, offset: 0x266d7): do_fork_idle <401600> DW_AT_decl_file : 3 <401601> DW_AT_decl_line : 638 <401603> DW_AT_prototyped : 1 <401603> DW_AT_low_pc : 0xffffffff814a32bb <40160b> DW_AT_high_pc : 0xffffffff814a32dd <401613> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) <401615> DW_AT_GNU_all_call_sites: 1 <401615> DW_AT_sibling : <0x40165b> <2><401619>: Abbrev Number: 91 (DW_TAG_formal_parameter) <40161a> DW_AT_name : (indirect string, offset: 0x10f8da): work <40161e> DW_AT_decl_file : 3 <40161f> DW_AT_decl_line : 638 <401621> DW_AT_type : <0x3f96c9> <401625> DW_AT_location : 0x7fb55 (location list) <2><401629>: Abbrev Number: 110 (DW_TAG_variable) <40162a> DW_AT_name : (indirect string, offset: 0x1109a7): c_idle -- <679053> DW_AT_name : (indirect string, offset: 0x1b1e0): do_fork <679057> DW_AT_decl_file : 25 <679058> DW_AT_decl_line : 2269 <67905a> DW_AT_prototyped : 1 <67905a> DW_AT_type : <0x66a9b5> <67905e> DW_AT_declaration : 1 <67905e> DW_AT_sibling : <0x679081> <2><679062>: Abbrev Number: 12 (DW_TAG_formal_parameter) <679063> DW_AT_type : <0x66a872> <2><679067>: Abbrev Number: 12 (DW_TAG_formal_parameter) <679068> DW_AT_type : <0x66a872> <2><67906c>: Abbrev Number: 12 (DW_TAG_formal_parameter) <67906d> DW_AT_type : <0x66c935> <2><679071>: Abbrev Number: 12 (DW_TAG_formal_parameter) <679072> DW_AT_type : <0x66a872> <2><679076>: Abbrev Number: 12 (DW_TAG_formal_parameter) <679077> DW_AT_type : <0x66b877> -- <723f0b> DW_AT_name : (indirect string, offset: 0x1b1e0): do_fork <723f0f> DW_AT_decl_file : 4 <723f10> DW_AT_decl_line : 1476 <723f12> DW_AT_prototyped : 1 <723f12> DW_AT_type : <0x70caad> <723f16> DW_AT_low_pc : 0xffffffff81056ee1 <723f1e> DW_AT_high_pc : 0xffffffff81057149 <723f26> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa) <723f28> DW_AT_GNU_all_call_sites: 1 <723f28> DW_AT_sibling : <0x7244fd> <2><723f2c>: Abbrev Number: 96 (DW_TAG_formal_parameter) <723f2d> DW_AT_name : (indirect string, offset: 0x146df): clone_flags <723f31> DW_AT_decl_file : 4 <723f32> DW_AT_decl_line : 1476 <723f34> DW_AT_type : <0x70ca0d> <723f38> DW_AT_location : 0x10db3b (location list) <2><723f3c>: Abbrev Number: 96 (DW_TAG_formal_parameter) -- <33629b6> DW_AT_name : (indirect string, offset: 0x124058): run_do_fork_test <33629ba> DW_AT_decl_file : 2 <33629bb> DW_AT_decl_line : 858 <33629bd> DW_AT_prototyped : 1 <33629bd> DW_AT_inline : 1 (inlined) <1><33629be>: Abbrev Number: 71 (DW_TAG_subprogram) <33629bf> DW_AT_name : (indirect string, offset: 0x123c3d): run_sys_open_test <33629c3> DW_AT_decl_file : 2 <33629c4> DW_AT_decl_line : 867 <33629c6> DW_AT_prototyped : 1 <33629c6> DW_AT_inline : 1 (inlined) <1><33629c7>: Abbrev Number: 64 (DW_TAG_subprogram) <33629c8> DW_AT_name : (indirect string, offset: 0x123e9e): kgdbts_option_setup <33629cc> DW_AT_decl_file : 2 <33629cd> DW_AT_decl_line : 985 <33629cf> DW_AT_prototyped : 1 <33629cf> DW_AT_type : <0x335570d> -- <33651ea> DW_AT_name : (indirect string, offset: 0x12405c): do_fork_test <33651ee> DW_AT_decl_file : 2 <33651ef> DW_AT_decl_line : 522 <33651f1> DW_AT_type : <0x33651d9> <33651f5> DW_AT_location : 9 byte block: 3 30 87 a7 81 ff ff ff ff (DW_OP_addr: ffffffff81a78730) <1><33651ff>: Abbrev Number: 122 (DW_TAG_variable) <3365200> DW_AT_name : (indirect string, offset: 0x123c41): sys_open_test <3365204> DW_AT_decl_file : 2 <3365205> DW_AT_decl_line : 540 <3365207> DW_AT_type : <0x33651d9> <336520b> DW_AT_location : 9 byte block: 3 b0 88 a7 81 ff ff ff ff (DW_OP_addr: ffffffff81a788b0) <1><3365215>: Abbrev Number: 122 (DW_TAG_variable) <3365216> DW_AT_name : (indirect string, offset: 0x123b83): hw_breakpoint_test <336521a> DW_AT_decl_file : 2 <336521b> DW_AT_decl_line : 558 <336521d> DW_AT_type : <0x3365167> <3365221> DW_AT_location : 9 byte block: 3 30 8a a7 81 ff ff ff ff (DW_OP_addr: ffffffff81a78a30)
> At least we must consider this lazy_line case. If I understand correctly, > that can also affect find_probe_point_lazy(sp_die, pf); > > If I find the different attribute, I'd like to add a checker function and > filter it out at early step in this function. >
Based on the above comments I have redone the patch:
If die entries corresponding to declarations appear before definition entry, probe finder returns error instead of continuing to look further for a definition entry.
This patch ensures we reach to the die entry corresponding to the definition and get the function address.
V2: A simpler solution based on Masami's suggestion.
Signed-off-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com> ---
tools/perf/util/probe-finder.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index 5d73262..fc59df2 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -963,10 +963,11 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data) struct dwarf_callback_param *param = data; struct probe_finder *pf = param->data; struct perf_probe_point *pp = &pf->pev->point; + Dwarf_Attribute attr;
/* Check tag and diename */ if (dwarf_tag(sp_die) != DW_TAG_subprogram || - !die_compare_name(sp_die, pp->function)) + !die_compare_name(sp_die, pp->function) || dwarf_attr(sp_die, DW_AT_declaration, &attr)) return DWARF_CB_OK;
/* Check declared file */
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