1 /*
2 * Copyright (C) 2012 Oracle.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, see http://www.gnu.org/copyleft/gpl.txt
16 */
17
18 /*
19 * This test is used to warn about mixups between bit shifters and bit flags.
20 *
21 */
22
23 #include "smatch.h"
24 #include "smatch_function_hashtable.h"
25
26 static int my_id;
27
28 static DEFINE_HASHTABLE_INSERT(insert_struct, char, int);
29 static DEFINE_HASHTABLE_SEARCH(search_struct, char, int);
30 static struct hashtable *shifters;
31
get_shifter(struct expression * expr)32 static const char *get_shifter(struct expression *expr)
33 {
34 const char *name;
35 sval_t expr_value;
36 const int *shifter_value;
37
38 expr = strip_expr(expr);
39 if (expr->type != EXPR_VALUE)
40 return NULL;
41 if (!get_value(expr, &expr_value))
42 return NULL;
43 name = pos_ident(expr->pos);
44 if (!name)
45 return NULL;
46 shifter_value = search_struct(shifters, (char *)name);
47 if (!shifter_value)
48 return NULL;
49 if (sval_cmp_val(expr_value, *shifter_value) != 0)
50 return NULL;
51 return name;
52 }
53
match_assign(struct expression * expr)54 static void match_assign(struct expression *expr)
55 {
56 const char *name;
57
58 if (expr->op != SPECIAL_OR_ASSIGN)
59 return;
60 if (positions_eq(expr->pos, expr->right->pos))
61 return;
62 name = get_shifter(expr->right);
63 if (!name)
64 return;
65
66 sm_warning("'%s' is a shifter (not for '%s').",
67 name, show_special(expr->op));
68 }
69
match_binop(struct expression * expr)70 static void match_binop(struct expression *expr)
71 {
72 const char *name;
73
74 if (positions_eq(expr->pos, expr->right->pos))
75 return;
76 if (expr->op != '&')
77 return;
78 name = get_shifter(expr->right);
79 if (!name)
80 return;
81
82 sm_warning("bit shifter '%s' used for logical '%s'",
83 name, show_special(expr->op));
84 }
85
register_shifters(void)86 static void register_shifters(void)
87 {
88 char filename[256];
89 struct token *token;
90 char *name;
91 int *val;
92
93 snprintf(filename, sizeof(filename), "%s.bit_shifters", option_project_str);
94 token = get_tokens_file(filename);
95 if (!token)
96 return;
97 if (token_type(token) != TOKEN_STREAMBEGIN)
98 return;
99 token = token->next;
100 while (token_type(token) != TOKEN_STREAMEND) {
101 if (token_type(token) != TOKEN_IDENT)
102 return;
103 name = alloc_string(show_ident(token->ident));
104 token = token->next;
105 if (token_type(token) != TOKEN_NUMBER)
106 return;
107 val = malloc(sizeof(int));
108 *val = atoi(token->number);
109 insert_struct(shifters, name, val);
110 token = token->next;
111 }
112 clear_token_alloc();
113 }
114
match_binop_info(struct expression * expr)115 static void match_binop_info(struct expression *expr)
116 {
117 char *name;
118 sval_t sval;
119
120 if (positions_eq(expr->pos, expr->right->pos))
121 return;
122 if (expr->op != SPECIAL_LEFTSHIFT)
123 return;
124 if (expr->right->type != EXPR_VALUE)
125 return;
126 name = pos_ident(expr->right->pos);
127 if (!name)
128 return;
129 if (!get_value(expr->right, &sval))
130 return;
131 sm_msg("info: bit shifter '%s' '%s'", name, sval_to_str(sval));
132 }
133
match_call(const char * fn,struct expression * expr,void * _arg_no)134 static void match_call(const char *fn, struct expression *expr, void *_arg_no)
135 {
136 struct expression *arg_expr;
137 int arg_no = PTR_INT(_arg_no);
138 sval_t sval;
139 char *name;
140
141 arg_expr = get_argument_from_call_expr(expr->args, arg_no);
142 if (positions_eq(expr->pos, arg_expr->pos))
143 return;
144 name = pos_ident(arg_expr->pos);
145 if (!name)
146 return;
147 if (!get_value(arg_expr, &sval))
148 return;
149 sm_msg("info: bit shifter '%s' '%s'", name, sval_to_str(sval));
150 }
151
check_bit_shift(int id)152 void check_bit_shift(int id)
153 {
154 my_id = id;
155
156 shifters = create_function_hashtable(5000);
157 register_shifters();
158
159 add_hook(&match_assign, ASSIGNMENT_HOOK);
160 add_hook(&match_binop, BINOP_HOOK);
161
162 if (option_info) {
163 add_hook(&match_binop_info, BINOP_HOOK);
164 if (option_project == PROJ_KERNEL) {
165 add_function_hook("set_bit", &match_call, INT_PTR(0));
166 add_function_hook("test_bit", &match_call, INT_PTR(0));
167 }
168 }
169 }
170