From 6b4827ad028a1ab2fc4dcf1f5e6e077018d1b770 Mon Sep 17 00:00:00 2001 From: Tom Zanussi Date: Thu, 3 Mar 2016 12:54:50 -0600 Subject: [PATCH] tracing: Add hist trigger 'execname' modifier Allow users to have common_pid field values displayed as program names in the output by appending '.execname' to a common_pid field name: # echo hist:keys=common_pid.execname ... \ [ if filter] > event/trigger Link: http://lkml.kernel.org/r/e172e81f10f5b8d1f08450e3763c850f39fbf698.1457029949.git.tom.zanussi@linux.intel.com Signed-off-by: Tom Zanussi Tested-by: Masami Hiramatsu Reviewed-by: Namhyung Kim Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 3 +- kernel/trace/trace_events_hist.c | 100 ++++++++++++++++++++++++++++++- 2 files changed, 101 insertions(+), 2 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 34459eb0c844..58a8bee50c6e 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -3857,7 +3857,8 @@ static const char readme_msg[] = "\t following modifiers to the field name, as applicable:\n\n" "\t .hex display a number as a hex value\n" "\t .sym display an address as a symbol\n" - "\t .sym-offset display an address as a symbol and offset\n\n" + "\t .sym-offset display an address as a symbol and offset\n" + "\t .execname display a common_pid as a program name\n\n" "\t The 'pause' parameter can be used to pause an existing hist\n" "\t trigger or to start a hist trigger but not log any events\n" "\t until told to do so. 'continue' can be used to start or\n" diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 808cc06cdb61..227e6c21b1eb 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -83,6 +83,7 @@ enum hist_field_flags { HIST_FIELD_FL_HEX = 8, HIST_FIELD_FL_SYM = 16, HIST_FIELD_FL_SYM_OFFSET = 32, + HIST_FIELD_FL_EXECNAME = 64, }; struct hist_trigger_attrs { @@ -232,6 +233,73 @@ static struct hist_trigger_attrs *parse_hist_trigger_attrs(char *trigger_str) return ERR_PTR(ret); } +static inline void save_comm(char *comm, struct task_struct *task) +{ + if (!task->pid) { + strcpy(comm, ""); + return; + } + + if (WARN_ON_ONCE(task->pid < 0)) { + strcpy(comm, ""); + return; + } + + memcpy(comm, task->comm, TASK_COMM_LEN); +} + +static void hist_trigger_elt_comm_free(struct tracing_map_elt *elt) +{ + kfree((char *)elt->private_data); +} + +static int hist_trigger_elt_comm_alloc(struct tracing_map_elt *elt) +{ + struct hist_trigger_data *hist_data = elt->map->private_data; + struct hist_field *key_field; + unsigned int i; + + for_each_hist_key_field(i, hist_data) { + key_field = hist_data->fields[i]; + + if (key_field->flags & HIST_FIELD_FL_EXECNAME) { + unsigned int size = TASK_COMM_LEN + 1; + + elt->private_data = kzalloc(size, GFP_KERNEL); + if (!elt->private_data) + return -ENOMEM; + break; + } + } + + return 0; +} + +static void hist_trigger_elt_comm_copy(struct tracing_map_elt *to, + struct tracing_map_elt *from) +{ + char *comm_from = from->private_data; + char *comm_to = to->private_data; + + if (comm_from) + memcpy(comm_to, comm_from, TASK_COMM_LEN + 1); +} + +static void hist_trigger_elt_comm_init(struct tracing_map_elt *elt) +{ + char *comm = elt->private_data; + + if (comm) + save_comm(comm, current); +} + +static const struct tracing_map_ops hist_trigger_elt_comm_ops = { + .elt_alloc = hist_trigger_elt_comm_alloc, + .elt_copy = hist_trigger_elt_comm_copy, + .elt_free = hist_trigger_elt_comm_free, + .elt_init = hist_trigger_elt_comm_init, +}; + static void destroy_hist_field(struct hist_field *hist_field) { kfree(hist_field); @@ -403,6 +471,9 @@ static int create_key_field(struct hist_trigger_data *hist_data, flags |= HIST_FIELD_FL_SYM; else if (strcmp(field_str, "sym-offset") == 0) flags |= HIST_FIELD_FL_SYM_OFFSET; + else if ((strcmp(field_str, "execname") == 0) && + (strcmp(field_name, "common_pid") == 0)) + flags |= HIST_FIELD_FL_EXECNAME; else { ret = -EINVAL; goto out; @@ -624,11 +695,27 @@ static int create_tracing_map_fields(struct hist_trigger_data *hist_data) return 0; } +static bool need_tracing_map_ops(struct hist_trigger_data *hist_data) +{ + struct hist_field *key_field; + unsigned int i; + + for_each_hist_key_field(i, hist_data) { + key_field = hist_data->fields[i]; + + if (key_field->flags & HIST_FIELD_FL_EXECNAME) + return true; + } + + return false; +} + static struct hist_trigger_data * create_hist_data(unsigned int map_bits, struct hist_trigger_attrs *attrs, struct trace_event_file *file) { + const struct tracing_map_ops *map_ops = NULL; struct hist_trigger_data *hist_data; int ret = 0; @@ -646,8 +733,11 @@ create_hist_data(unsigned int map_bits, if (ret) goto free; + if (need_tracing_map_ops(hist_data)) + map_ops = &hist_trigger_elt_comm_ops; + hist_data->map = tracing_map_create(map_bits, hist_data->key_size, - NULL, hist_data); + map_ops, hist_data); if (IS_ERR(hist_data->map)) { ret = PTR_ERR(hist_data->map); hist_data->map = NULL; @@ -758,6 +848,12 @@ hist_trigger_entry_print(struct seq_file *m, sprint_symbol(str, uval); seq_printf(m, "%s: [%llx] %-55s", key_field->field->name, uval, str); + } else if (key_field->flags & HIST_FIELD_FL_EXECNAME) { + char *comm = elt->private_data; + + uval = *(u64 *)(key + key_field->offset); + seq_printf(m, "%s: %-16s[%10llu]", + key_field->field->name, comm, uval); } else if (key_field->flags & HIST_FIELD_FL_STRING) { seq_printf(m, "%s: %-50s", key_field->field->name, (char *)(key + key_field->offset)); @@ -877,6 +973,8 @@ static const char *get_hist_field_flags(struct hist_field *hist_field) flags_str = "sym"; else if (hist_field->flags & HIST_FIELD_FL_SYM_OFFSET) flags_str = "sym-offset"; + else if (hist_field->flags & HIST_FIELD_FL_EXECNAME) + flags_str = "execname"; return flags_str; }