tracing: Add hist_debug trace event files for histogram debugging
Add a new "hist_debug" file for each trace event, which when read will dump out a bunch of internal details about the hist triggers defined on that event. This is normally off but can be enabled by saying 'y' to the new CONFIG_HIST_TRIGGERS_DEBUG config option. This is in support of the new Documentation file describing histogram internals, Documentation/trace/histogram-design.rst, which was requested by developers trying to understand the internals when extending or making use of the hist triggers for higher-level tools. The histogram-design.rst documentation refers to the hist_debug files and demonstrates their use with output in the test examples. Link: http://lkml.kernel.org/r/77914c22b0ba493d9783c53bbfbc6087d6a7e1b1.1585941485.git.zanussi@kernel.org Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Tom Zanussi
committed by
Steven Rostedt (VMware)
Steven Rostedt (VMware)
parent
16b585fe71
commit
2d19bd79ae
@@ -6478,6 +6478,279 @@ const struct file_operations event_hist_fops = {
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.release = single_release,
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};
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#ifdef CONFIG_HIST_TRIGGERS_DEBUG
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static void hist_field_debug_show_flags(struct seq_file *m,
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unsigned long flags)
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{
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seq_puts(m, " flags:\n");
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if (flags & HIST_FIELD_FL_KEY)
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seq_puts(m, " HIST_FIELD_FL_KEY\n");
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else if (flags & HIST_FIELD_FL_HITCOUNT)
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seq_puts(m, " VAL: HIST_FIELD_FL_HITCOUNT\n");
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else if (flags & HIST_FIELD_FL_VAR)
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seq_puts(m, " HIST_FIELD_FL_VAR\n");
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else if (flags & HIST_FIELD_FL_VAR_REF)
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seq_puts(m, " HIST_FIELD_FL_VAR_REF\n");
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else
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seq_puts(m, " VAL: normal u64 value\n");
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if (flags & HIST_FIELD_FL_ALIAS)
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seq_puts(m, " HIST_FIELD_FL_ALIAS\n");
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}
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static int hist_field_debug_show(struct seq_file *m,
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struct hist_field *field, unsigned long flags)
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{
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if ((field->flags & flags) != flags) {
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seq_printf(m, "ERROR: bad flags - %lx\n", flags);
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return -EINVAL;
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}
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hist_field_debug_show_flags(m, field->flags);
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if (field->field)
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seq_printf(m, " ftrace_event_field name: %s\n",
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field->field->name);
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if (field->flags & HIST_FIELD_FL_VAR) {
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seq_printf(m, " var.name: %s\n", field->var.name);
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seq_printf(m, " var.idx (into tracing_map_elt.vars[]): %u\n",
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field->var.idx);
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}
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if (field->flags & HIST_FIELD_FL_ALIAS)
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seq_printf(m, " var_ref_idx (into hist_data->var_refs[]): %u\n",
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field->var_ref_idx);
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if (field->flags & HIST_FIELD_FL_VAR_REF) {
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seq_printf(m, " name: %s\n", field->name);
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seq_printf(m, " var.idx (into tracing_map_elt.vars[]): %u\n",
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field->var.idx);
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seq_printf(m, " var.hist_data: %p\n", field->var.hist_data);
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seq_printf(m, " var_ref_idx (into hist_data->var_refs[]): %u\n",
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field->var_ref_idx);
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if (field->system)
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seq_printf(m, " system: %s\n", field->system);
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if (field->event_name)
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seq_printf(m, " event_name: %s\n", field->event_name);
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}
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seq_printf(m, " type: %s\n", field->type);
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seq_printf(m, " size: %u\n", field->size);
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seq_printf(m, " is_signed: %u\n", field->is_signed);
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return 0;
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}
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static int field_var_debug_show(struct seq_file *m,
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struct field_var *field_var, unsigned int i,
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bool save_vars)
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{
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const char *vars_name = save_vars ? "save_vars" : "field_vars";
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struct hist_field *field;
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int ret = 0;
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seq_printf(m, "\n hist_data->%s[%d]:\n", vars_name, i);
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field = field_var->var;
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seq_printf(m, "\n %s[%d].var:\n", vars_name, i);
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hist_field_debug_show_flags(m, field->flags);
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seq_printf(m, " var.name: %s\n", field->var.name);
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seq_printf(m, " var.idx (into tracing_map_elt.vars[]): %u\n",
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field->var.idx);
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field = field_var->val;
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seq_printf(m, "\n %s[%d].val:\n", vars_name, i);
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if (field->field)
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seq_printf(m, " ftrace_event_field name: %s\n",
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field->field->name);
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else {
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ret = -EINVAL;
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goto out;
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}
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seq_printf(m, " type: %s\n", field->type);
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seq_printf(m, " size: %u\n", field->size);
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seq_printf(m, " is_signed: %u\n", field->is_signed);
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out:
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return ret;
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}
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static int hist_action_debug_show(struct seq_file *m,
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struct action_data *data, int i)
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{
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int ret = 0;
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if (data->handler == HANDLER_ONMAX ||
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data->handler == HANDLER_ONCHANGE) {
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seq_printf(m, "\n hist_data->actions[%d].track_data.var_ref:\n", i);
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ret = hist_field_debug_show(m, data->track_data.var_ref,
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HIST_FIELD_FL_VAR_REF);
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if (ret)
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goto out;
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seq_printf(m, "\n hist_data->actions[%d].track_data.track_var:\n", i);
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ret = hist_field_debug_show(m, data->track_data.track_var,
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HIST_FIELD_FL_VAR);
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if (ret)
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goto out;
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}
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if (data->handler == HANDLER_ONMATCH) {
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seq_printf(m, "\n hist_data->actions[%d].match_data.event_system: %s\n",
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i, data->match_data.event_system);
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seq_printf(m, " hist_data->actions[%d].match_data.event: %s\n",
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i, data->match_data.event);
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}
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out:
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return ret;
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}
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static int hist_actions_debug_show(struct seq_file *m,
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struct hist_trigger_data *hist_data)
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{
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int i, ret = 0;
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if (hist_data->n_actions)
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seq_puts(m, "\n action tracking variables (for onmax()/onchange()/onmatch()):\n");
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for (i = 0; i < hist_data->n_actions; i++) {
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struct action_data *action = hist_data->actions[i];
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ret = hist_action_debug_show(m, action, i);
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if (ret)
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goto out;
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}
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if (hist_data->n_save_vars)
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seq_puts(m, "\n save action variables (save() params):\n");
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for (i = 0; i < hist_data->n_save_vars; i++) {
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ret = field_var_debug_show(m, hist_data->save_vars[i], i, true);
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if (ret)
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goto out;
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}
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out:
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return ret;
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}
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static void hist_trigger_debug_show(struct seq_file *m,
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struct event_trigger_data *data, int n)
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{
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struct hist_trigger_data *hist_data;
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int i, ret;
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if (n > 0)
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seq_puts(m, "\n\n");
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seq_puts(m, "# event histogram\n#\n# trigger info: ");
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data->ops->print(m, data->ops, data);
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seq_puts(m, "#\n\n");
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hist_data = data->private_data;
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seq_printf(m, "hist_data: %p\n\n", hist_data);
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seq_printf(m, " n_vals: %u\n", hist_data->n_vals);
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seq_printf(m, " n_keys: %u\n", hist_data->n_keys);
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seq_printf(m, " n_fields: %u\n", hist_data->n_fields);
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seq_puts(m, "\n val fields:\n\n");
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seq_puts(m, " hist_data->fields[0]:\n");
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ret = hist_field_debug_show(m, hist_data->fields[0],
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HIST_FIELD_FL_HITCOUNT);
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if (ret)
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return;
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for (i = 1; i < hist_data->n_vals; i++) {
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seq_printf(m, "\n hist_data->fields[%d]:\n", i);
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ret = hist_field_debug_show(m, hist_data->fields[i], 0);
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if (ret)
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return;
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}
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seq_puts(m, "\n key fields:\n");
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for (i = hist_data->n_vals; i < hist_data->n_fields; i++) {
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seq_printf(m, "\n hist_data->fields[%d]:\n", i);
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ret = hist_field_debug_show(m, hist_data->fields[i],
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HIST_FIELD_FL_KEY);
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if (ret)
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return;
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}
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if (hist_data->n_var_refs)
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seq_puts(m, "\n variable reference fields:\n");
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for (i = 0; i < hist_data->n_var_refs; i++) {
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seq_printf(m, "\n hist_data->var_refs[%d]:\n", i);
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ret = hist_field_debug_show(m, hist_data->var_refs[i],
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HIST_FIELD_FL_VAR_REF);
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if (ret)
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return;
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}
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if (hist_data->n_field_vars)
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seq_puts(m, "\n field variables:\n");
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for (i = 0; i < hist_data->n_field_vars; i++) {
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ret = field_var_debug_show(m, hist_data->field_vars[i], i, false);
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if (ret)
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return;
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}
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ret = hist_actions_debug_show(m, hist_data);
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if (ret)
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return;
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}
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static int hist_debug_show(struct seq_file *m, void *v)
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{
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struct event_trigger_data *data;
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struct trace_event_file *event_file;
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int n = 0, ret = 0;
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mutex_lock(&event_mutex);
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event_file = event_file_data(m->private);
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if (unlikely(!event_file)) {
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ret = -ENODEV;
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goto out_unlock;
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}
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list_for_each_entry(data, &event_file->triggers, list) {
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if (data->cmd_ops->trigger_type == ETT_EVENT_HIST)
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hist_trigger_debug_show(m, data, n++);
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}
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out_unlock:
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mutex_unlock(&event_mutex);
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return ret;
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}
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static int event_hist_debug_open(struct inode *inode, struct file *file)
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{
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int ret;
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ret = security_locked_down(LOCKDOWN_TRACEFS);
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if (ret)
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return ret;
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return single_open(file, hist_debug_show, file);
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}
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const struct file_operations event_hist_debug_fops = {
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.open = event_hist_debug_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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#endif
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static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
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{
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const char *field_name = hist_field_name(hist_field, 0);
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