mirror of https://gitee.com/openkylin/linux.git
tracing: Add hist trigger support for variable reference aliases
Add support for alias=$somevar where alias can be used as onmatch.xxx($alias). Aliases are a way of creating a new name for an existing variable, for flexibly in making naming more clear in certain cases. For example in the below the user perhaps feels that using $new_lat in the synthetic event invocation is opaque or doesn't fit well stylistically with previous triggers, so creates an alias of $new_lat named $latency and uses that in the call instead: # echo 'hist:keys=next_pid:new_lat=common_timestamp.usecs' > /sys/kernel/debug/tracing/events/sched/sched_switch/trigger # echo 'hist:keys=pid:latency=$new_lat: onmatch(sched.sched_switch).wake2($latency,pid)' > /sys/kernel/debug/tracing/events/synthetic/wake1/trigger Link: http://lkml.kernel.org/r/ef20a65d921af3a873a6f1e8c71407c926d5586f.1516069914.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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@ -228,6 +228,7 @@ enum hist_field_flags {
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HIST_FIELD_FL_EXPR = 1 << 13,
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HIST_FIELD_FL_VAR_REF = 1 << 14,
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HIST_FIELD_FL_CPU = 1 << 15,
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HIST_FIELD_FL_ALIAS = 1 << 16,
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};
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struct var_defs {
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@ -1609,7 +1610,8 @@ static const char *hist_field_name(struct hist_field *field,
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if (field->field)
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field_name = field->field->name;
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else if (field->flags & HIST_FIELD_FL_LOG2)
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else if (field->flags & HIST_FIELD_FL_LOG2 ||
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field->flags & HIST_FIELD_FL_ALIAS)
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field_name = hist_field_name(field->operands[0], ++level);
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else if (field->flags & HIST_FIELD_FL_TIMESTAMP)
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field_name = "common_timestamp";
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@ -2080,7 +2082,7 @@ static struct hist_field *create_hist_field(struct hist_trigger_data *hist_data,
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hist_field->hist_data = hist_data;
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if (flags & HIST_FIELD_FL_EXPR)
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if (flags & HIST_FIELD_FL_EXPR || flags & HIST_FIELD_FL_ALIAS)
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goto out; /* caller will populate */
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if (flags & HIST_FIELD_FL_VAR_REF) {
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@ -2217,10 +2219,18 @@ static int init_var_ref(struct hist_field *ref_field,
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}
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}
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ref_field->name = kstrdup(var_field->var.name, GFP_KERNEL);
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if (!ref_field->name) {
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err = -ENOMEM;
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goto free;
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if (var_field->var.name) {
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ref_field->name = kstrdup(var_field->var.name, GFP_KERNEL);
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if (!ref_field->name) {
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err = -ENOMEM;
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goto free;
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}
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} else if (var_field->name) {
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ref_field->name = kstrdup(var_field->name, GFP_KERNEL);
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if (!ref_field->name) {
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err = -ENOMEM;
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goto free;
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}
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}
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ref_field->type = kstrdup(var_field->type, GFP_KERNEL);
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@ -2382,6 +2392,28 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
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return field;
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}
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static struct hist_field *create_alias(struct hist_trigger_data *hist_data,
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struct hist_field *var_ref,
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char *var_name)
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{
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struct hist_field *alias = NULL;
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unsigned long flags = HIST_FIELD_FL_ALIAS | HIST_FIELD_FL_VAR;
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alias = create_hist_field(hist_data, NULL, flags, var_name);
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if (!alias)
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return NULL;
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alias->fn = var_ref->fn;
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alias->operands[0] = var_ref;
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if (init_var_ref(alias, var_ref, var_ref->system, var_ref->event_name)) {
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destroy_hist_field(alias, 0);
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return NULL;
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}
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return alias;
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}
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static struct hist_field *parse_atom(struct hist_trigger_data *hist_data,
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struct trace_event_file *file, char *str,
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unsigned long *flags, char *var_name)
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@ -2415,6 +2447,13 @@ static struct hist_field *parse_atom(struct hist_trigger_data *hist_data,
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if (hist_field) {
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hist_data->var_refs[hist_data->n_var_refs] = hist_field;
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hist_field->var_ref_idx = hist_data->n_var_refs++;
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if (var_name) {
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hist_field = create_alias(hist_data, hist_field, var_name);
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if (!hist_field) {
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ret = -ENOMEM;
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goto out;
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}
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}
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return hist_field;
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}
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} else
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@ -2515,6 +2554,26 @@ static int check_expr_operands(struct hist_field *operand1,
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unsigned long operand1_flags = operand1->flags;
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unsigned long operand2_flags = operand2->flags;
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if ((operand1_flags & HIST_FIELD_FL_VAR_REF) ||
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(operand1_flags & HIST_FIELD_FL_ALIAS)) {
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struct hist_field *var;
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var = find_var_field(operand1->var.hist_data, operand1->name);
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if (!var)
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return -EINVAL;
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operand1_flags = var->flags;
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}
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if ((operand2_flags & HIST_FIELD_FL_VAR_REF) ||
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(operand2_flags & HIST_FIELD_FL_ALIAS)) {
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struct hist_field *var;
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var = find_var_field(operand2->var.hist_data, operand2->name);
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if (!var)
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return -EINVAL;
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operand2_flags = var->flags;
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}
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if ((operand1_flags & HIST_FIELD_FL_TIMESTAMP_USECS) !=
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(operand2_flags & HIST_FIELD_FL_TIMESTAMP_USECS))
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return -EINVAL;
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@ -4646,7 +4705,8 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
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else if (hist_field->flags & HIST_FIELD_FL_CPU)
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seq_puts(m, "cpu");
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else if (field_name) {
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if (hist_field->flags & HIST_FIELD_FL_VAR_REF)
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if (hist_field->flags & HIST_FIELD_FL_VAR_REF ||
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hist_field->flags & HIST_FIELD_FL_ALIAS)
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seq_putc(m, '$');
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seq_printf(m, "%s", field_name);
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}
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