tools lib traceevent: Added support for __get_bitmask() macro

Coming in v3.16, trace events will be able to save bitmasks in raw
format in the ring buffer and output it with the __get_bitmask() macro.

In order for userspace tools to parse this, it must be able to handle
the __get_bitmask() call and be able to convert the data that's in
the ring buffer into a nice bitmask format. The output is similar to
what the kernel uses to print bitmasks, with a comma separator every
4 bytes (8 characters).

This allows for cpumasks to also be saved efficiently.

The first user is the thermal:thermal_power_limit event which has the
following output:

 thermal_power_limit:  cpus=0000000f freq=1900000 cdev_state=0 power=5252

Link: http://lkml.kernel.org/r/20140506132238.22e136d1@gandalf.local.home

Suggested-by: Javi Merino <javi.merino@arm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Javi Merino <javi.merino@arm.com>
Link: http://lkml.kernel.org/r/20140603032224.229186537@goodmis.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

2 files changed, 120 insertions, 0 deletions

diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c
index b83184f2d484..93825a17dcce 100644
--- a/tools/lib/traceevent/event-parse.c
+++ b/tools/lib/traceevent/event-parse.c
@@ -765,6 +765,9 @@ static void free_arg(struct print_arg *arg)
         case PRINT_BSTRING:
                 free(arg->string.string);
                 break;
+        case PRINT_BITMASK:
+                free(arg->bitmask.bitmask);
+                break;
         case PRINT_DYNAMIC_ARRAY:
                 free(arg->dynarray.index);
                 break;
@@ -2268,6 +2271,7 @@ static int arg_num_eval(struct print_arg *arg, long long *val)
         case PRINT_FIELD ... PRINT_SYMBOL:
         case PRINT_STRING:
         case PRINT_BSTRING:
+        case PRINT_BITMASK:
         default:
                 do_warning("invalid eval type %d", arg->type);
                 ret = 0;
@@ -2296,6 +2300,7 @@ static char *arg_eval (struct print_arg *arg)
         case PRINT_FIELD ... PRINT_SYMBOL:
         case PRINT_STRING:
         case PRINT_BSTRING:
+        case PRINT_BITMASK:
         default:
                 do_warning("invalid eval type %d", arg->type);
                 break;
@@ -2683,6 +2688,35 @@ process_str(struct event_format *event __maybe_unused, struct print_arg *arg,
         return EVENT_ERROR;
 }
 
+static enum event_type
+process_bitmask(struct event_format *event __maybe_unused, struct print_arg *arg,
+            char **tok)
+{
+        enum event_type type;
+        char *token;
+
+        if (read_expect_type(EVENT_ITEM, &token) < 0)
+                goto out_free;
+
+        arg->type = PRINT_BITMASK;
+        arg->bitmask.bitmask = token;
+        arg->bitmask.offset = -1;
+
+        if (read_expected(EVENT_DELIM, ")") < 0)
+                goto out_err;
+
+        type = read_token(&token);
+        *tok = token;
+
+        return type;
+
+ out_free:
+        free_token(token);
+ out_err:
+        *tok = NULL;
+        return EVENT_ERROR;
+}
+
 static struct pevent_function_handler *
 find_func_handler(struct pevent *pevent, char *func_name)
 {
@@ -2797,6 +2831,10 @@ process_function(struct event_format *event, struct print_arg *arg,
                 free_token(token);
                 return process_str(event, arg, tok);
         }
+        if (strcmp(token, "__get_bitmask") == 0) {
+                free_token(token);
+                return process_bitmask(event, arg, tok);
+        }
         if (strcmp(token, "__get_dynamic_array") == 0) {
                 free_token(token);
                 return process_dynamic_array(event, arg, tok);
@@ -3324,6 +3362,7 @@ eval_num_arg(void *data, int size, struct event_format *event, struct print_arg
                 return eval_type(val, arg, 0);
         case PRINT_STRING:
         case PRINT_BSTRING:
+        case PRINT_BITMASK:
                 return 0;
         case PRINT_FUNC: {
                 struct trace_seq s;
@@ -3556,6 +3595,60 @@ static void print_str_to_seq(struct trace_seq *s, const char *format,
                 trace_seq_printf(s, format, str);
 }
 
+static void print_bitmask_to_seq(struct pevent *pevent,
+                                 struct trace_seq *s, const char *format,
+                                 int len_arg, const void *data, int size)
+{
+        int nr_bits = size * 8;
+        int str_size = (nr_bits + 3) / 4;
+        int len = 0;
+        char buf[3];
+        char *str;
+        int index;
+        int i;
+
+        /*
+         * The kernel likes to put in commas every 32 bits, we
+         * can do the same.
+         */
+        str_size += (nr_bits - 1) / 32;
+
+        str = malloc(str_size + 1);
+        if (!str) {
+                do_warning("%s: not enough memory!", __func__);
+                return;
+        }
+        str[str_size] = 0;
+
+        /* Start out with -2 for the two chars per byte */
+        for (i = str_size - 2; i >= 0; i -= 2) {
+                /*
+                 * data points to a bit mask of size bytes.
+                 * In the kernel, this is an array of long words, thus
+                 * endianess is very important.
+                 */
+                if (pevent->file_bigendian)
+                        index = size - (len + 1);
+                else
+                        index = len;
+
+                snprintf(buf, 3, "%02x", *((unsigned char *)data + index));
+                memcpy(str + i, buf, 2);
+                len++;
+                if (!(len & 3) && i > 0) {
+                        i--;
+                        str[i] = ',';
+                }
+        }
+
+        if (len_arg >= 0)
+                trace_seq_printf(s, format, len_arg, str);
+        else
+                trace_seq_printf(s, format, str);
+
+        free(str);
+}
+
 static void print_str_arg(struct trace_seq *s, void *data, int size,
                           struct event_format *event, const char *format,
                           int len_arg, struct print_arg *arg)
@@ -3691,6 +3784,23 @@ static void print_str_arg(struct trace_seq *s, void *data, int size,
         case PRINT_BSTRING:
                 print_str_to_seq(s, format, len_arg, arg->string.string);
                 break;
+        case PRINT_BITMASK: {
+                int bitmask_offset;
+                int bitmask_size;
+
+                if (arg->bitmask.offset == -1) {
+                        struct format_field *f;
+
+                        f = pevent_find_any_field(event, arg->bitmask.bitmask);
+                        arg->bitmask.offset = f->offset;
+                }
+                bitmask_offset = data2host4(pevent, data + arg->bitmask.offset);
+                bitmask_size = bitmask_offset >> 16;
+                bitmask_offset &= 0xffff;
+                print_bitmask_to_seq(pevent, s, format, len_arg,
+                                     data + bitmask_offset, bitmask_size);
+                break;
+        }
         case PRINT_OP:
                 /*
                  * The only op for string should be ? :
@@ -4822,6 +4932,9 @@ static void print_args(struct print_arg *args)
         case PRINT_BSTRING:
                 printf("__get_str(%s)", args->string.string);
                 break;
+        case PRINT_BITMASK:
+                printf("__get_bitmask(%s)", args->bitmask.bitmask);
+                break;
         case PRINT_TYPE:
                 printf("(%s)", args->typecast.type);
                 print_args(args->typecast.item);
diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
index 56e0e6c12411..7a3873ff9a4f 100644
--- a/tools/lib/traceevent/event-parse.h
+++ b/tools/lib/traceevent/event-parse.h
@@ -208,6 +208,11 @@ struct print_arg_string {
         int                     offset;
 };
 
+struct print_arg_bitmask {
+        char                    *bitmask;
+        int                     offset;
+};
+
 struct print_arg_field {
         char                    *name;
         struct format_field     *field;
@@ -274,6 +279,7 @@ enum print_arg_type {
         PRINT_DYNAMIC_ARRAY,
         PRINT_OP,
         PRINT_FUNC,
+        PRINT_BITMASK,
 };
 
 struct print_arg {
@@ -288,6 +294,7 @@ struct print_arg {
                 struct print_arg_hex            hex;
                 struct print_arg_func           func;
                 struct print_arg_string         string;
+                struct print_arg_bitmask        bitmask;
                 struct print_arg_op             op;
                 struct print_arg_dynarray       dynarray;
         };