scripts/gcc-plugins/sancov_plugin.c

   1 /*
   2  * Copyright 2011-2016 by Emese Revfy <re.emese@gmail.com>
   3  * Licensed under the GPL v2, or (at your option) v3
   4  *
   5  * Homepage:
   6  * https://github.com/ephox-gcc-plugins/sancov
   7  *
   8  * This plugin inserts a __sanitizer_cov_trace_pc() call at the start of basic blocks.
   9  * It supports all gcc versions with plugin support (from gcc-4.5 on).
  10  * It is based on the commit "Add fuzzing coverage support" by Dmitry Vyukov <dvyukov@google.com>.
  11  *
  12  * You can read about it more here:
  13  *  https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296
  14  *  https://lwn.net/Articles/674854/
  15  *  https://github.com/google/syzkaller
  16  *  https://lwn.net/Articles/677764/
  17  *
  18  * Usage:
  19  * make run
  20  */
  21
  22 #include "gcc-common.h"
  23
  24 __visible int plugin_is_GPL_compatible;
  25
  26 tree sancov_fndecl;
  27
  28 static struct plugin_info sancov_plugin_info = {
  29         .version        = "20160402",
  30         .help           = "sancov plugin\n",
  31 };
  32
  33 static unsigned int sancov_execute(void)
  34 {
  35         basic_block bb;
  36
  37         /* Remove this line when this plugin and kcov will be in the kernel.
  38         if (!strcmp(DECL_NAME_POINTER(current_function_decl), DECL_NAME_POINTER(sancov_fndecl)))
  39                 return 0;
  40         */
  41
  42         FOR_EACH_BB_FN(bb, cfun) {
  43                 const_gimple stmt;
  44                 gcall *gcall;
  45                 gimple_stmt_iterator gsi = gsi_after_labels(bb);
  46
  47                 if (gsi_end_p(gsi))
  48                         continue;
  49
  50                 stmt = gsi_stmt(gsi);
  51                 gcall = as_a_gcall(gimple_build_call(sancov_fndecl, 0));
  52                 gimple_set_location(gcall, gimple_location(stmt));
  53                 gsi_insert_before(&gsi, gcall, GSI_SAME_STMT);
  54         }
  55         return 0;
  56 }
  57
  58 #define PASS_NAME sancov
  59
  60 #define NO_GATE
  61 #define TODO_FLAGS_FINISH TODO_dump_func | TODO_verify_stmts | TODO_update_ssa_no_phi | TODO_verify_flow
  62
  63 #include "gcc-generate-gimple-pass.h"
  64
  65 static void sancov_start_unit(void __unused *gcc_data, void __unused *user_data)
  66 {
  67         tree leaf_attr, nothrow_attr;
  68         tree BT_FN_VOID = build_function_type_list(void_type_node, NULL_TREE);
  69
  70         sancov_fndecl = build_fn_decl("__sanitizer_cov_trace_pc", BT_FN_VOID);
  71
  72         DECL_ASSEMBLER_NAME(sancov_fndecl);
  73         TREE_PUBLIC(sancov_fndecl) = 1;
  74         DECL_EXTERNAL(sancov_fndecl) = 1;
  75         DECL_ARTIFICIAL(sancov_fndecl) = 1;
  76         DECL_PRESERVE_P(sancov_fndecl) = 1;
  77         DECL_UNINLINABLE(sancov_fndecl) = 1;
  78         TREE_USED(sancov_fndecl) = 1;
  79
  80         nothrow_attr = tree_cons(get_identifier("nothrow"), NULL, NULL);
  81         decl_attributes(&sancov_fndecl, nothrow_attr, 0);
  82         gcc_assert(TREE_NOTHROW(sancov_fndecl));
  83         leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL);
  84         decl_attributes(&sancov_fndecl, leaf_attr, 0);
  85 }
  86
  87 __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
  88 {
  89         int i;
  90         const char * const plugin_name = plugin_info->base_name;
  91         const int argc = plugin_info->argc;
  92         const struct plugin_argument * const argv = plugin_info->argv;
  93         bool enable = true;
  94
  95         static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = {
  96                 {
  97                         .base = &sancov_fndecl,
  98                         .nelt = 1,
  99                         .stride = sizeof(sancov_fndecl),
 100                         .cb = &gt_ggc_mx_tree_node,
 101                         .pchw = &gt_pch_nx_tree_node
 102                 },
 103                 LAST_GGC_ROOT_TAB
 104         };
 105
 106         /* BBs can be split afterwards?? */
 107         PASS_INFO(sancov, "asan", 0, PASS_POS_INSERT_BEFORE);
 108
 109         if (!plugin_default_version_check(version, &gcc_version)) {
 110                 error(G_("incompatible gcc/plugin versions"));
 111                 return 1;
 112         }
 113
 114         for (i = 0; i < argc; ++i) {
 115                 if (!strcmp(argv[i].key, "no-sancov")) {
 116                         enable = false;
 117                         continue;
 118                 }
 119                 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
 120         }
 121
 122         register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info);
 123
 124         if (!enable)
 125                 return 0;
 126
 127 #if BUILDING_GCC_VERSION < 6000
 128         register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL);
 129         register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)&gt_ggc_r_gt_sancov);
 130         register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_pass_info);
 131 #endif
 132
 133         return 0;
 134 }