139 lines
4.5 KiB
Diff
139 lines
4.5 KiB
Diff
From: Tom Zanussi <tom.zanussi@linux.intel.com>
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Date: Wed, 6 Dec 2017 16:38:11 -0600
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Subject: [PATCH 30/37] tracing: Add hist trigger support for variable
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reference aliases
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.14/older/patches-4.14.6-rt7.tar.xz
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Add support for alias=$somevar where alias can be used as
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onmatch.xxx($alias).
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Aliases are a way of creating a new name for an existing variable, for
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flexibly in making naming more clear in certain cases. For example in
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the below the user perhaps feels that using $new_lat in the synthetic
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event invocation is opaque or doesn't fit well stylistically with
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previous triggers, so creates an alias of $new_lat named $latency and
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uses that in the call instead:
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# echo 'hist:keys=next_pid:new_lat=common_timestamp.usecs' >
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/sys/kernel/debug/tracing/events/sched/sched_switch/trigger
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# echo 'hist:keys=pid:latency=$new_lat:
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onmatch(sched.sched_switch).wake2($latency,pid)' >
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/sys/kernel/debug/tracing/events/synthetic/wake1/trigger
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Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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kernel/trace/trace_events_hist.c | 58 ++++++++++++++++++++++++++++++++++++---
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1 file changed, 55 insertions(+), 3 deletions(-)
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--- a/kernel/trace/trace_events_hist.c
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+++ b/kernel/trace/trace_events_hist.c
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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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@@ -1626,7 +1627,8 @@ static const char *hist_field_name(struc
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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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@@ -2095,7 +2097,7 @@ static struct hist_field *create_hist_fi
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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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@@ -2395,6 +2397,28 @@ parse_field(struct hist_trigger_data *hi
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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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+
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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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+
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+ alias->fn = var_ref->fn;
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+ alias->operands[0] = var_ref;
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+
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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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+
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+ return alias;
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+}
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+
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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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@@ -2428,6 +2452,13 @@ struct hist_field *parse_atom(struct his
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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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@@ -2532,6 +2563,26 @@ static int check_expr_operands(struct hi
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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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+
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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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+
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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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+
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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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+
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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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@@ -4661,7 +4712,8 @@ static void hist_field_print(struct seq_
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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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