Add 'verbose' plugin parameter for stackleak gcc plugin.
It can be used for printing additional info about the kernel code
instrumentation.

For using it add the following to scripts/Makefile.gcc-plugins:
  gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \
    += -fplugin-arg-stackleak_plugin-verbose

Signed-off-by: Alexander Popov <alex.po...@linux.com>
---
 scripts/gcc-plugins/stackleak_plugin.c | 31 +++++++++++++++++++++-----
 1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/scripts/gcc-plugins/stackleak_plugin.c 
b/scripts/gcc-plugins/stackleak_plugin.c
index 0769c5b9156d..19358712d4ed 100644
--- a/scripts/gcc-plugins/stackleak_plugin.c
+++ b/scripts/gcc-plugins/stackleak_plugin.c
@@ -33,6 +33,8 @@ __visible int plugin_is_GPL_compatible;
 static int track_frame_size = -1;
 static bool build_for_x86 = false;
 static const char track_function[] = "stackleak_track_stack";
+static bool disable = false;
+static bool verbose = false;
 
 /*
  * Mark these global variables (roots) for gcc garbage collector since
@@ -45,6 +47,7 @@ static struct plugin_info stackleak_plugin_info = {
        .help = "track-min-size=nn\ttrack stack for functions with a stack 
frame size >= nn bytes\n"
                "arch=target_arch\tspecify target build arch\n"
                "disable\t\tdo not activate the plugin\n"
+               "verbose\t\tprint info about the instrumentation\n"
 };
 
 static void add_stack_tracking_gcall(gimple_stmt_iterator *gsi)
@@ -98,6 +101,10 @@ static tree get_current_stack_pointer_decl(void)
                return var;
        }
 
+       if (verbose) {
+               fprintf(stderr, "stackleak: missing current_stack_pointer in 
%s()\n",
+                       DECL_NAME_POINTER(current_function_decl));
+       }
        return NULL_TREE;
 }
 
@@ -366,6 +373,7 @@ static bool remove_stack_tracking_gasm(void)
  */
 static unsigned int stackleak_cleanup_execute(void)
 {
+       const char *fn = DECL_NAME_POINTER(current_function_decl);
        bool removed = false;
 
        /*
@@ -376,11 +384,17 @@ static unsigned int stackleak_cleanup_execute(void)
         * For more info see gcc commit 7072df0aae0c59ae437e.
         * Let's leave such functions instrumented.
         */
-       if (cfun->calls_alloca)
+       if (cfun->calls_alloca) {
+               if (verbose)
+                       fprintf(stderr, "stackleak: instrument %s() old\n", fn);
                return 0;
+       }
 
-       if (large_stack_frame())
+       if (large_stack_frame()) {
+               if (verbose)
+                       fprintf(stderr, "stackleak: instrument %s()\n", fn);
                return 0;
+       }
 
        if (lookup_attribute_spec(get_identifier("no_caller_saved_registers")))
                removed = remove_stack_tracking_gasm();
@@ -506,9 +520,6 @@ __visible int plugin_init(struct plugin_name_args 
*plugin_info,
 
        /* Parse the plugin arguments */
        for (i = 0; i < argc; i++) {
-               if (!strcmp(argv[i].key, "disable"))
-                       return 0;
-
                if (!strcmp(argv[i].key, "track-min-size")) {
                        if (!argv[i].value) {
                                error(G_("no value supplied for option 
'-fplugin-arg-%s-%s'"),
@@ -531,6 +542,10 @@ __visible int plugin_init(struct plugin_name_args 
*plugin_info,
 
                        if (!strcmp(argv[i].value, "x86"))
                                build_for_x86 = true;
+               } else if (!strcmp(argv[i].key, "disable")) {
+                       disable = true;
+               } else if (!strcmp(argv[i].key, "verbose")) {
+                       verbose = true;
                } else {
                        error(G_("unknown option '-fplugin-arg-%s-%s'"),
                                        plugin_name, argv[i].key);
@@ -538,6 +553,12 @@ __visible int plugin_init(struct plugin_name_args 
*plugin_info,
                }
        }
 
+       if (disable) {
+               if (verbose)
+                       fprintf(stderr, "stackleak: disabled for this 
translation unit\n");
+               return 0;
+       }
+
        /* Give the information about the plugin */
        register_callback(plugin_name, PLUGIN_INFO, NULL,
                                                &stackleak_plugin_info);
-- 
2.25.2

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