perf tools: Add --debug optionto set debug variable

Adding --debug option as a way to setup debug variables.  Starting with
support for verbose, more will come.

It's possible to use it now with report command:
  $ perf --debug verbose   ...
  $ perf --debug verbose=2 ...

I'll need this support to add separated debug variable for ordered
events change in order to separate debug output out of standard verbose
stream.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20140717105500.GG516@krava.redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

4 files changed, 67 insertions, 2 deletions

diff --git a/tools/perf/Documentation/perf.txt b/tools/perf/Documentation/perf.txt
index 0eeb247dc7d2..d240bb2e5b22 100644
--- a/tools/perf/Documentation/perf.txt
+++ b/tools/perf/Documentation/perf.txt
@@ -8,7 +8,15 @@ perf - Performance analysis tools for Linux
 SYNOPSIS
 --------
 [verse]
-'perf' [--version] [--help] COMMAND [ARGS]
+'perf' [--version] [--help] [OPTIONS] COMMAND [ARGS]
+
+OPTIONS
+-------
+--debug::
+        Setup debug variable (just verbose for now) in value
+        range (0, 10). Use like:
+          --debug verbose   # sets verbose = 1
+          --debug verbose=2 # sets verbose = 2
 
 DESCRIPTION
 -----------
diff --git a/tools/perf/perf.c b/tools/perf/perf.c
index 95c58fc15284..eed3fb2a3af0 100644
--- a/tools/perf/perf.c
+++ b/tools/perf/perf.c
@@ -13,11 +13,12 @@
 #include "util/quote.h"
 #include "util/run-command.h"
 #include "util/parse-events.h"
+#include "util/debug.h"
 #include <api/fs/debugfs.h>
 #include <pthread.h>
 
 const char perf_usage_string[] =
-        "perf [--version] [--help] COMMAND [ARGS]";
+        "perf [--version] [--debug variable[=VALUE]] [--help] COMMAND [ARGS]";
 
 const char perf_more_info_string[] =
         "See 'perf help COMMAND' for more information on a specific command.";
@@ -212,6 +213,16 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
                                 printf("%s ", p->cmd);
                         }
                         exit(0);
+                } else if (!strcmp(cmd, "--debug")) {
+                        if (*argc < 2) {
+                                fprintf(stderr, "No variable specified for --debug.\n");
+                                usage(perf_usage_string);
+                        }
+                        if (perf_debug_option((*argv)[1]))
+                                usage(perf_usage_string);
+
+                        (*argv)++;
+                        (*argc)--;
                 } else {
                         fprintf(stderr, "Unknown option: %s\n", cmd);
                         usage(perf_usage_string);
diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
index c208d6f56e63..71d419362634 100644
--- a/tools/perf/util/debug.c
+++ b/tools/perf/util/debug.c
@@ -105,3 +105,47 @@ void trace_event(union perf_event *event)
         }
         printf(".\n");
 }
+
+static struct debug_variable {
+        const char *name;
+        int *ptr;
+} debug_variables[] = {
+        { .name = "verbose", .ptr = &verbose },
+        { .name = NULL, }
+};
+
+int perf_debug_option(const char *str)
+{
+        struct debug_variable *var = &debug_variables[0];
+        char *vstr, *s = strdup(str);
+        int v = 1;
+
+        vstr = strchr(s, '=');
+        if (vstr)
+                *vstr++ = 0;
+
+        while (var->name) {
+                if (!strcmp(s, var->name))
+                        break;
+                var++;
+        }
+
+        if (!var->name) {
+                pr_err("Unknown debug variable name '%s'\n", s);
+                free(s);
+                return -1;
+        }
+
+        if (vstr) {
+                v = atoi(vstr);
+                /*
+                 * Allow only values in range (0, 10),
+                 * otherwise set 0.
+                 */
+                v = (v < 0) || (v > 10) ? 0 : v;
+        }
+
+        *var->ptr = v;
+        free(s);
+        return 0;
+}
diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
index 1cb808123242..89fb6b0f7ab2 100644
--- a/tools/perf/util/debug.h
+++ b/tools/perf/util/debug.h
@@ -39,4 +39,6 @@ void pr_stat(const char *fmt, ...);
 
 int eprintf(int level, int var, const char *fmt, ...) __attribute__((format(printf, 3, 4)));
 
+int perf_debug_option(const char *str);
+
 #endif  /* __PERF_DEBUG_H */