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Emese Revfy543c37c2016-05-24 00:11:37 +02001/*
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 * http://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
24int 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#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
89int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
90{
91 int i;
92 struct register_pass_info sancov_plugin_pass_info;
93 const char * const plugin_name = plugin_info->base_name;
94 const int argc = plugin_info->argc;
95 const struct plugin_argument * const argv = plugin_info->argv;
96 bool enable = true;
97
98 static const struct ggc_root_tab gt_ggc_r_gt_sancov[] = {
99 {
100 .base = &sancov_fndecl,
101 .nelt = 1,
102 .stride = sizeof(sancov_fndecl),
103 .cb = &gt_ggc_mx_tree_node,
104 .pchw = &gt_pch_nx_tree_node
105 },
106 LAST_GGC_ROOT_TAB
107 };
108
109 /* BBs can be split afterwards?? */
110 sancov_plugin_pass_info.pass = make_sancov_pass();
111#if BUILDING_GCC_VERSION >= 4009
112 sancov_plugin_pass_info.reference_pass_name = "asan";
113#else
114 sancov_plugin_pass_info.reference_pass_name = "nrv";
115#endif
116 sancov_plugin_pass_info.ref_pass_instance_number = 0;
117 sancov_plugin_pass_info.pos_op = PASS_POS_INSERT_BEFORE;
118
119 if (!plugin_default_version_check(version, &gcc_version)) {
120 error(G_("incompatible gcc/plugin versions"));
121 return 1;
122 }
123
124 for (i = 0; i < argc; ++i) {
125 if (!strcmp(argv[i].key, "no-sancov")) {
126 enable = false;
127 continue;
128 }
129 error(G_("unkown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
130 }
131
132 register_callback(plugin_name, PLUGIN_INFO, NULL, &sancov_plugin_info);
133
134 if (!enable)
135 return 0;
136
137#if BUILDING_GCC_VERSION < 6000
138 register_callback(plugin_name, PLUGIN_START_UNIT, &sancov_start_unit, NULL);
139 register_callback(plugin_name, PLUGIN_REGISTER_GGC_ROOTS, NULL, (void *)&gt_ggc_r_gt_sancov);
140 register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL, &sancov_plugin_pass_info);
141#endif
142
143 return 0;
144}