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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: 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.localdomain Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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3 changed files with 22 additions and 8 deletions
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@ -277,6 +277,21 @@ bool die_is_func_def(Dwarf_Die *dw_die)
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dwarf_attr(dw_die, DW_AT_declaration, &attr) == NULL);
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}
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/**
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* die_is_func_instance - Ensure that this DIE is an instance of a subprogram
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* @dw_die: a DIE
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*
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* Ensure that this DIE is an instance (which has an entry address).
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* This returns true if @dw_die is a function instance. If not, you need to
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* call die_walk_instances() to find actual instances.
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**/
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bool die_is_func_instance(Dwarf_Die *dw_die)
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{
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Dwarf_Addr tmp;
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/* Actually gcc optimizes non-inline as like as inlined */
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return !dwarf_func_inline(dw_die) && dwarf_entrypc(dw_die, &tmp) == 0;
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}
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/**
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* die_get_data_member_location - Get the data-member offset
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* @mb_die: a DIE of a member of a data structure
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@ -41,6 +41,9 @@ extern int cu_walk_functions_at(Dwarf_Die *cu_die, Dwarf_Addr addr,
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/* Ensure that this DIE is a subprogram and definition (not declaration) */
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extern bool die_is_func_def(Dwarf_Die *dw_die);
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/* Ensure that this DIE is an instance of a subprogram */
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extern bool die_is_func_instance(Dwarf_Die *dw_die);
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/* Compare diename and tname */
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extern bool die_compare_name(Dwarf_Die *dw_die, const char *tname);
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@ -915,17 +915,13 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
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dwarf_decl_line(sp_die, &pf->lno);
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pf->lno += pp->line;
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param->retval = find_probe_point_by_line(pf);
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} else if (!dwarf_func_inline(sp_die)) {
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} else if (die_is_func_instance(sp_die)) {
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/* Instances always have the entry address */
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dwarf_entrypc(sp_die, &pf->addr);
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/* Real function */
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if (pp->lazy_line)
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param->retval = find_probe_point_lazy(sp_die, pf);
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else {
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if (dwarf_entrypc(sp_die, &pf->addr) != 0) {
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pr_warning("Failed to get entry address of "
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"%s.\n", dwarf_diename(sp_die));
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param->retval = -ENOENT;
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return DWARF_CB_ABORT;
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}
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pf->addr += pp->offset;
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/* TODO: Check the address in this function */
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param->retval = call_probe_finder(sp_die, pf);
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@ -1536,7 +1532,7 @@ static int line_range_search_cb(Dwarf_Die *sp_die, void *data)
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pr_debug("New line range: %d to %d\n", lf->lno_s, lf->lno_e);
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lr->start = lf->lno_s;
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lr->end = lf->lno_e;
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if (dwarf_func_inline(sp_die))
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if (!die_is_func_instance(sp_die))
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param->retval = die_walk_instances(sp_die,
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line_range_inline_cb, lf);
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else
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