Messages in this thread | | | Date | Mon, 26 Mar 2012 19:51:10 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RESEND]Re: [PATCH] perf - probe finder fails to resolve function name to address |
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(2012/03/26 19:06), Prashanth Nageshappa wrote: > Fixing a coding style issue.. > > 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
OK, compared with mine, this attribute is actually new one for this kind of (declaration) entries.
[...] >> >> 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>
Well, OK. This looks good for me too :)
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
> --- > > tools/perf/util/probe-finder.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c > index 5d73262..d5914ee 100644 > --- a/tools/perf/util/probe-finder.c > +++ b/tools/perf/util/probe-finder.c > @@ -963,10 +963,12 @@ 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 */ > >
-- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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