3.16.82-rc1 review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu mhiramat@kernel.org
commit da6cb952a89efe24bb76c4971370d485737a2d85 upstream.
Filter out instances except for inlined_subroutine and subprogram DIE in die_walk_instances() and die_is_func_instance().
This fixes an issue that perf probe sets some probes on calling address instead of a target function itself.
When perf probe walks on instances of an abstruct origin (a kind of function prototype of inlined function), die_walk_instances() can also pass a GNU_call_site (a GNU extension for call site) to callback. Since it is not an inlined instance of target function, we have to filter out when searching a probe point.
Without this patch, perf probe sets probes on call site address too.This can happen on some function which is marked "inlined", but has actual symbol. (I'm not sure why GCC mark it "inlined"):
# perf probe -D vfs_read p:probe/vfs_read _text+2500017 p:probe/vfs_read_1 _text+2499468 p:probe/vfs_read_2 _text+2499563 p:probe/vfs_read_3 _text+2498876 p:probe/vfs_read_4 _text+2498512 p:probe/vfs_read_5 _text+2498627
With this patch:
Slightly different results, similar tho:
# perf probe -D vfs_read p:probe/vfs_read _text+2498512
Committer testing:
# uname -a Linux quaco 5.3.8-200.fc30.x86_64 #1 SMP Tue Oct 29 14:46:22 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
Before:
# perf probe -D vfs_read p:probe/vfs_read _text+3131557 p:probe/vfs_read_1 _text+3130975 p:probe/vfs_read_2 _text+3131047 p:probe/vfs_read_3 _text+3130380 p:probe/vfs_read_4 _text+3130000 # uname -a Linux quaco 5.3.8-200.fc30.x86_64 #1 SMP Tue Oct 29 14:46:22 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux #
After:
# perf probe -D vfs_read p:probe/vfs_read _text+3130000 #
Fixes: db0d2c6420ee ("perf probe: Search concrete out-of-line instances") Signed-off-by: Masami Hiramatsu mhiramat@kernel.org Tested-by: Arnaldo Carvalho de Melo acme@redhat.com Cc: Jiri Olsa jolsa@redhat.com Cc: Namhyung Kim namhyung@kernel.org Link: http://lore.kernel.org/lkml/157241937063.32002.11024544873990816590.stgit@de... Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- tools/perf/util/dwarf-aux.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)
--- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -304,18 +304,22 @@ int die_entrypc(Dwarf_Die *dw_die, Dwarf * @dw_die: a DIE * * Ensure that this DIE is an instance (which has an entry address). - * This returns true if @dw_die is a function instance. If not, you need to - * call die_walk_instances() to find actual instances. + * This returns true if @dw_die is a function instance. If not, the @dw_die + * must be a prototype. You can use die_walk_instances() to find actual + * instances. **/ bool die_is_func_instance(Dwarf_Die *dw_die) { Dwarf_Addr tmp; Dwarf_Attribute attr_mem; + int tag = dwarf_tag(dw_die);
- /* Actually gcc optimizes non-inline as like as inlined */ - return !dwarf_func_inline(dw_die) && - (dwarf_entrypc(dw_die, &tmp) == 0 || - dwarf_attr(dw_die, DW_AT_ranges, &attr_mem) != NULL); + if (tag != DW_TAG_subprogram && + tag != DW_TAG_inlined_subroutine) + return false; + + return dwarf_entrypc(dw_die, &tmp) == 0 || + dwarf_attr(dw_die, DW_AT_ranges, &attr_mem) != NULL; }
/** @@ -557,6 +561,9 @@ static int __die_walk_instances_cb(Dwarf Dwarf_Die *origin; int tmp;
+ if (!die_is_func_instance(inst)) + return DIE_FIND_CB_CONTINUE; + attr = dwarf_attr(inst, DW_AT_abstract_origin, &attr_mem); if (attr == NULL) return DIE_FIND_CB_CONTINUE;