LXR linux/scripts/gcc-plugins/sancov

   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
  26tree sancov_fndecl;
  27
  28static struct plugin_info sancov_plugin_info = {
  29        .version        = "20160402",
  30        .help           = "sancov plugin\n",
  31};
  32
  33static 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
  65static 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}
 135