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    Subject[PATCH v14 08/22] tracing: Add hist trigger 'hex' modifier for displaying numeric fields
    Date
    Allow users to have numeric fields displayed as hex values in the
    output by appending '.hex' to field names:

    # echo hist:keys=aaa,bbb.hex:vals=ccc.hex ... \
    [ if filter] > event/trigger

    Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
    Tested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
    Reviewed-by: Namhyung Kim <namhyung@kernel.org>
    ---
    kernel/trace/trace.c | 5 +++-
    kernel/trace/trace_events_hist.c | 62 ++++++++++++++++++++++++++++++++++++----
    2 files changed, 60 insertions(+), 7 deletions(-)

    diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
    index 9f0ab15..d6b4692 100644
    --- a/kernel/trace/trace.c
    +++ b/kernel/trace/trace.c
    @@ -3843,7 +3843,10 @@ static const char readme_msg[] =
    "\t used to specify more or fewer than the default 2048 entries\n"
    "\t for the hashtable size.\n\n"
    "\t Reading the 'hist' file for the event will dump the hash\n"
    - "\t table in its entirety to stdout.\n\n"
    + "\t table in its entirety to stdout. The default format used to\n"
    + "\t display a given field can be modified by appending any of the\n"
    + "\t following modifiers to the field name, as applicable:\n\n"
    + "\t .hex display a number as a hex value\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 69cf3d9..734cdce 100644
    --- a/kernel/trace/trace_events_hist.c
    +++ b/kernel/trace/trace_events_hist.c
    @@ -80,6 +80,7 @@ enum hist_field_flags {
    HIST_FIELD_FL_HITCOUNT = 1,
    HIST_FIELD_FL_KEY = 2,
    HIST_FIELD_FL_STRING = 4,
    + HIST_FIELD_FL_HEX = 8,
    };

    struct hist_trigger_attrs {
    @@ -301,11 +302,23 @@ static int create_val_field(struct hist_trigger_data *hist_data,
    {
    struct ftrace_event_field *field = NULL;
    unsigned long flags = 0;
    + char *field_name;
    int ret = 0;

    if (WARN_ON(val_idx >= TRACING_MAP_VALS_MAX))
    return -EINVAL;
    - field = trace_find_event_field(file->event_call, field_str);
    +
    + field_name = strsep(&field_str, ".");
    + if (field_str) {
    + if (strcmp(field_str, "hex") == 0)
    + flags |= HIST_FIELD_FL_HEX;
    + else {
    + ret = -EINVAL;
    + goto out;
    + }
    + }
    +
    + field = trace_find_event_field(file->event_call, field_name);
    if (!field) {
    ret = -EINVAL;
    goto out;
    @@ -368,6 +381,7 @@ static int create_key_field(struct hist_trigger_data *hist_data,
    struct ftrace_event_field *field = NULL;
    unsigned long flags = 0;
    unsigned int key_size;
    + char *field_name;
    int ret = 0;

    if (WARN_ON(key_idx >= TRACING_MAP_FIELDS_MAX))
    @@ -375,7 +389,17 @@ static int create_key_field(struct hist_trigger_data *hist_data,

    flags |= HIST_FIELD_FL_KEY;

    - field = trace_find_event_field(file->event_call, field_str);
    + field_name = strsep(&field_str, ".");
    + if (field_str) {
    + if (strcmp(field_str, "hex") == 0)
    + flags |= HIST_FIELD_FL_HEX;
    + else {
    + ret = -EINVAL;
    + goto out;
    + }
    + }
    +
    + field = trace_find_event_field(file->event_call, field_name);
    if (!field) {
    ret = -EINVAL;
    goto out;
    @@ -707,7 +731,11 @@ hist_trigger_entry_print(struct seq_file *m,
    if (i > hist_data->n_vals)
    seq_puts(m, ", ");

    - if (key_field->flags & HIST_FIELD_FL_STRING) {
    + if (key_field->flags & HIST_FIELD_FL_HEX) {
    + uval = *(u64 *)(key + key_field->offset);
    + seq_printf(m, "%s: %llx",
    + key_field->field->name, uval);
    + } else if (key_field->flags & HIST_FIELD_FL_STRING) {
    seq_printf(m, "%s: %-50s", key_field->field->name,
    (char *)(key + key_field->offset));
    } else {
    @@ -723,9 +751,15 @@ hist_trigger_entry_print(struct seq_file *m,
    tracing_map_read_sum(elt, HITCOUNT_IDX));

    for (i = 1; i < hist_data->n_vals; i++) {
    - seq_printf(m, " %s: %10llu",
    - hist_data->fields[i]->field->name,
    - tracing_map_read_sum(elt, i));
    + if (hist_data->fields[i]->flags & HIST_FIELD_FL_HEX) {
    + seq_printf(m, " %s: %10llx",
    + hist_data->fields[i]->field->name,
    + tracing_map_read_sum(elt, i));
    + } else {
    + seq_printf(m, " %s: %10llu",
    + hist_data->fields[i]->field->name,
    + tracing_map_read_sum(elt, i));
    + }
    }

    seq_puts(m, "\n");
    @@ -810,9 +844,25 @@ const struct file_operations event_hist_fops = {
    .release = single_release,
    };

    +static const char *get_hist_field_flags(struct hist_field *hist_field)
    +{
    + const char *flags_str = NULL;
    +
    + if (hist_field->flags & HIST_FIELD_FL_HEX)
    + flags_str = "hex";
    +
    + return flags_str;
    +}
    +
    static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
    {
    seq_printf(m, "%s", hist_field->field->name);
    + if (hist_field->flags) {
    + const char *flags_str = get_hist_field_flags(hist_field);
    +
    + if (flags_str)
    + seq_printf(m, ".%s", flags_str);
    + }
    }

    static int event_hist_trigger_print(struct seq_file *m,
    --
    1.9.3
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