3.16.82-rc1 review patch. If anyone has any objections, please let me know.
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From: Masami Hiramatsu masami.hiramatsu.pt@hitachi.com
commit e1ecbbc3fa834cc6b4b344edb1968e734d57189b upstream.
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 masami.hiramatsu.pt@hitachi.com Tested-by: Arnaldo Carvalho de Melo acme@redhat.com Cc: Namhyung Kim namhyung@kernel.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lkml.kernel.org/r/20150130093744.30575.43290.stgit@localhost.localdom... 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 | 15 +++++++++++++++ tools/perf/util/dwarf-aux.h | 3 +++ tools/perf/util/probe-finder.c | 12 ++++-------- 3 files changed, 22 insertions(+), 8 deletions(-)
--- a/tools/perf/util/dwarf-aux.c +++ b/tools/perf/util/dwarf-aux.c @@ -278,6 +278,21 @@ bool die_is_func_def(Dwarf_Die *dw_die) }
/** + * 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 * @offs: The offset of the member in the data structure --- 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_Di /* 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);
--- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -909,17 +909,13 @@ static int probe_point_search_cb(Dwarf_D 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); @@ -1514,7 +1510,7 @@ static int line_range_search_cb(Dwarf_Di 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