scripts/gcc-plugins/sancov_plugin.c

0001 /*
0002  * Copyright 2011-2016 by Emese Revfy <re.emese@gmail.com>
0003  * Licensed under the GPL v2, or (at your option) v3
0004  *
0005  * Homepage:
0006  * https://github.com/ephox-gcc-plugins/sancov
0007  *
0008  * This plugin inserts a __sanitizer_cov_trace_pc() call at the start of basic blocks.
0009  * It supports all gcc versions with plugin support (from gcc-4.5 on).
0010  * It is based on the commit "Add fuzzing coverage support" by Dmitry Vyukov <dvyukov@google.com>.
0011  *
0012  * You can read about it more here:
0013  *  https://gcc.gnu.org/viewcvs/gcc?limit_changes=0&view=revision&revision=231296
0014  *  https://lwn.net/Articles/674854/
0015  *  https://github.com/google/syzkaller
0016  *  https://lwn.net/Articles/677764/
0017  *
0018  * Usage:
0019  * make run
0020  */
0021
0022 #include "gcc-common.h"
0023
0024 __visible int plugin_is_GPL_compatible;
0025
0026 tree sancov_fndecl;
0027
0028 static struct plugin_info sancov_plugin_info = {
0029     .version    = PLUGIN_VERSION,
0030     .help       = "sancov plugin\n",
0031 };
0032
0033 static unsigned int sancov_execute(void)
0034 {
0035     basic_block bb;
0036
0037     /* Remove this line when this plugin and kcov will be in the kernel.
0038     if (!strcmp(DECL_NAME_POINTER(current_function_decl), DECL_NAME_POINTER(sancov_fndecl)))
0039         return 0;
0040     */
0041
0042     FOR_EACH_BB_FN(bb, cfun) {
0043         const_gimple stmt;
0044         gcall *gcall;
0045         gimple_stmt_iterator gsi = gsi_after_labels(bb);
0046
0047         if (gsi_end_p(gsi))
0048             continue;
0049
0050         stmt = gsi_stmt(gsi);
0051         gcall = as_a_gcall(gimple_build_call(sancov_fndecl, 0));
0052         gimple_set_location(gcall, gimple_location(stmt));
0053         gsi_insert_before(&gsi, gcall, GSI_SAME_STMT);
0054     }
0055     return 0;
0056 }
0057
0058 #define PASS_NAME sancov
0059
0060 #define NO_GATE
0061 #define TODO_FLAGS_FINISH TODO_dump_func | TODO_verify_stmts | TODO_update_ssa_no_phi | TODO_verify_flow
0062
0063 #include "gcc-generate-gimple-pass.h"
0064
0065 static void sancov_start_unit(void __unused *gcc_data, void __unused *user_data)
0066 {
0067     tree leaf_attr, nothrow_attr;
0068     tree BT_FN_VOID = build_function_type_list(void_type_node, NULL_TREE);
0069
0070     sancov_fndecl = build_fn_decl("__sanitizer_cov_trace_pc", BT_FN_VOID);
0071
0072     DECL_ASSEMBLER_NAME(sancov_fndecl);
0073     TREE_PUBLIC(sancov_fndecl) = 1;
0074     DECL_EXTERNAL(sancov_fndecl) = 1;
0075     DECL_ARTIFICIAL(sancov_fndecl) = 1;
0076     DECL_PRESERVE_P(sancov_fndecl) = 1;
0077     DECL_UNINLINABLE(sancov_fndecl) = 1;
0078     TREE_USED(sancov_fndecl) = 1;
0079
0080     nothrow_attr = tree_cons(get_identifier("nothrow"), NULL, NULL);
0081     decl_attributes(&sancov_fndecl, nothrow_attr, 0);
0082     gcc_assert(TREE_NOTHROW(sancov_fndecl));
0083     leaf_attr = tree_cons(get_identifier("leaf"), NULL, NULL);
0084     decl_attributes(&sancov_fndecl, leaf_attr, 0);
0085 }
0086
0087 __visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
0088 {
0089     int i;
0090     const char * const plugin_name = plugin_info->base_name;
0091     const int argc = plugin_info->argc;
0092     const struct plugin_argument * const argv = plugin_info->argv;
0093     bool enable = true;
0094
0095     static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = {
0096         {
0097             .base = &sancov_fndecl,
0098             .nelt = 1,
0099             .stride = sizeof(sancov_fndecl),
0100             .cb = &gt_ggc_mx_tree_node,
0101             .pchw = &gt_pch_nx_tree_node
0102         },
0103         LAST_GGC_ROOT_TAB
0104     };
0105
0106     /* BBs can be split afterwards?? */
0107     PASS_INFO(sancov, "asan", 0, PASS_POS_INSERT_BEFORE);
0108
0109     if (!plugin_default_version_check(version, &gcc_version)) {
0110         error(G_("incompatible gcc/plugin versions"));
0111         return 1;
0112     }
0113
0114     for (i = 0; i < argc; ++i) {
0115         if (!strcmp(argv[i].key, "no-sancov")) {
0116             enable = false;
0117             continue;
0118         }
0119         error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
0120     }
0121
0122     register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info);
0123
0124     if (!enable)
0125         return 0;
0126
0127 #if BUILDING_GCC_VERSION < 6000
0128     register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL);
0129     register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)&gt_ggc_r_gt_sancov);
0130     register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_pass_info);
0131 #endif
0132
0133     return 0;
0134 }