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 #if BUILDING_GCC_VERSION > 4005 84 leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL); 85 decl_attributes(&sancov_fndecl, leaf_attr, 0); 86 #endif 87 } 88 89 __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version) 90 { 91 int i; 92 const char * const plugin_name = plugin_info->base_name; 93 const int argc = plugin_info->argc; 94 const struct plugin_argument * const argv = plugin_info->argv; 95 bool enable = true; 96 97 static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = { 98 { 99 .base = &sancov_fndecl, 100 .nelt = 1, 101 .stride = sizeof(sancov_fndecl), 102 .cb = >_ggc_mx_tree_node, 103 .pchw = >_pch_nx_tree_node 104 }, 105 LAST_GGC_ROOT_TAB 106 }; 107 108 /* BBs can be split afterwards?? */ 109 #if BUILDING_GCC_VERSION >= 4009 110 PASS_INFO(sancov, "asan", 0, PASS_POS_INSERT_BEFORE); 111 #else 112 PASS_INFO(sancov, "nrv", 1, PASS_POS_INSERT_BEFORE); 113 #endif 114 115 if (!plugin_default_version_check(version, &gcc_version)) { 116 error(G_("incompatible gcc/plugin versions")); 117 return 1; 118 } 119 120 for (i = 0; i < argc; ++i) { 121 if (!strcmp(argv[i].key, "no-sancov")) { 122 enable = false; 123 continue; 124 } 125 error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); 126 } 127 128 register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info); 129 130 if (!enable) 131 return 0; 132 133 #if BUILDING_GCC_VERSION < 6000 134 register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL); 135 register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)>_ggc_r_gt_sancov); 136 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_pass_info); 137 #endif 138 139 return 0; 140 } 141