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Commit e1ecbbc3 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Arnaldo Carvalho de Melo
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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: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Tested-by: default avatarArnaldo 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.localdomain


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent a3c0cc2a

tools/perf/util/dwarf-aux.c

+15 −0
Original line number Diff line number Diff line
@@ -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

tools/perf/util/dwarf-aux.h

+3 −0
Original line number Diff line number Diff line
@@ -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);

tools/perf/util/probe-finder.c

+4 −8
Original line number Diff line number Diff line
@@ -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