From e1ecbbc3fa834cc6b4b344edb1968e734d57189b Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Fri, 30 Jan 2015 18:37:44 +0900 Subject: [PATCH] perf probe: Fix to handle optimized not-inlined functions Fix to handle optimized no-inline functions which have only function definition but no actual instance at that point. To fix this problem, we need to find actual instance of the function. Without this patch: ---- # perf probe -a __up Failed to get entry address of __up. Error: Failed to add events. # perf probe -L __up Specified source line is not found. Error: Failed to show lines. ---- With this patch: ---- # perf probe -a __up Added new event: probe:__up (on __up) You can now use it in all perf tools, such as: perf record -e probe:__up -aR sleep 1 # perf probe -L __up <__up@/home/fedora/ksrc/linux-3/kernel/locking/semaphore.c:0> 0 static noinline void __sched __up(struct semaphore *sem) { struct semaphore_waiter *waiter = list_first_entry(&sem->wait_ struct semaphore_waite 4 list_del(&waiter->list); 5 waiter->up = true; 6 wake_up_process(waiter->task); 7 } ---- Signed-off-by: Masami Hiramatsu Tested-by: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20150130093744.30575.43290.stgit@localhost.localdomain Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/dwarf-aux.c | 15 +++++++++++++++ tools/perf/util/dwarf-aux.h | 3 +++ tools/perf/util/probe-finder.c | 12 ++++-------- 3 files changed, 22 insertions(+), 8 deletions(-) diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c index cc66c4049e09..780b2bc11128 100644 --- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -277,6 +277,21 @@ bool die_is_func_def(Dwarf_Die *dw_die) dwarf_attr(dw_die, DW_AT_declaration, &attr) == NULL); } +/** + * die_is_func_instance - Ensure that this DIE is an instance of a subprogram + * @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. + **/ +bool die_is_func_instance(Dwarf_Die *dw_die) +{ + Dwarf_Addr tmp; + + /* Actually gcc optimizes non-inline as like as inlined */ + return !dwarf_func_inline(dw_die) && dwarf_entrypc(dw_die, &tmp) == 0; +} /** * die_get_data_member_location - Get the data-member offset * @mb_die: a DIE of a member of a data structure diff --git a/tools/perf/util/dwarf-aux.h b/tools/perf/util/dwarf-aux.h index b4fe90c6cb2d..af7dbcd5f929 100644 --- a/tools/perf/util/dwarf-aux.h +++ b/tools/perf/util/dwarf-aux.h @@ -41,6 +41,9 @@ extern int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr, /* Ensure that this DIE is a subprogram and definition (not declaration) */ extern bool die_is_func_def(Dwarf_Die *dw_die); +/* Ensure that this DIE is an instance of a subprogram */ +extern bool die_is_func_instance(Dwarf_Die *dw_die); + /* Compare diename and tname */ extern bool die_compare_name(Dwarf_Die *dw_die, const char *tname); diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index b5247d777f0e..d14193518e4d 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -915,17 +915,13 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data) dwarf_decl_line(sp_die, &pf->lno); pf->lno += pp->line; param->retval = find_probe_point_by_line(pf); - } else if (!dwarf_func_inline(sp_die)) { + } else if (die_is_func_instance(sp_die)) { + /* Instances always have the entry address */ + dwarf_entrypc(sp_die, &pf->addr); /* Real function */ if (pp->lazy_line) param->retval = find_probe_point_lazy(sp_die, pf); else { - if (dwarf_entrypc(sp_die, &pf->addr) != 0) { - pr_warning("Failed to get entry address of " - "%s.\n", dwarf_diename(sp_die)); - param->retval = -ENOENT; - return DWARF_CB_ABORT; - } pf->addr += pp->offset; /* TODO: Check the address in this function */ param->retval = call_probe_finder(sp_die, pf); @@ -1536,7 +1532,7 @@ static int line_range_search_cb(Dwarf_Die *sp_die, void *data) pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e); lr->start = lf->lno_s; lr->end = lf->lno_e; - if (dwarf_func_inline(sp_die)) + if (!die_is_func_instance(sp_die)) param->retval = die_walk_instances(sp_die, line_range_inline_cb, lf); else -- 2.20.1