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 = PLUGIN_VERSION,
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 = >_ggc_mx_tree_node,
101 .pchw = >_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 *)>_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
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