check_readl_infinite_loops.c

   1 /*
   2  * Copyright (C) 2014 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 #include "smatch.h"
  19 #include "smatch_extra.h"
  20
  21 static int my_id;
  22
  23 STATE(readl);
  24 STATE(readl_ff);
  25 STATE(readl_00);
  26
  27 DECLARE_PTR_LIST(state_stack, struct smatch_state);
  28 struct state_stack *state_at_start;
  29
  30 static int readl_has_been_called;
  31 static int returned;
  32
  33 static int is_readl_call(struct expression *expr)
  34 {
  35         struct symbol *sym;
  36
  37         expr = strip_expr(expr);
  38         if (expr->type != EXPR_CALL)
  39                 return 0;
  40         if (expr->fn->type != EXPR_SYMBOL)
  41                 return 0;
  42         sym = expr->fn->symbol;
  43         if (!sym || !sym->ident)
  44                 return 0;
  45         if (strcmp(sym->ident->name, "readl") != 0)
  46                 return 0;
  47         return 1;
  48 }
  49
  50 static int is_readl(struct expression *expr)
  51 {
  52         if (is_readl_call(expr))
  53                 return 1;
  54         if (get_state_expr(my_id, expr) == &readl)
  55                 return 1;
  56         return 0;
  57 }
  58
  59 static void match_assign(struct expression *expr)
  60 {
  61         if (is_readl(expr->right))
  62                 set_state_expr(my_id, expr->left, &readl);
  63         else if (get_state_expr(my_id, expr->left))
  64                 set_state_expr(my_id, expr->left, &undefined);
  65 }
  66
  67 static int condition_depends_on_readl(struct expression *expr)
  68 {
  69         if (expr->type == EXPR_BINOP) {
  70                 if (condition_depends_on_readl(expr->left))
  71                         return 1;
  72                 if (condition_depends_on_readl(expr->right))
  73                         return 1;
  74                 return 0;
  75         }
  76         if (is_readl(expr))
  77                 return 1;
  78         return 0;
  79 }
  80
  81 static void check_condition(struct expression *expr)
  82 {
  83         if (expr->op != '&')
  84                 return;
  85         if (!condition_depends_on_readl(expr))
  86                 return;
  87         readl_has_been_called = 1;
  88         set_true_false_states(my_id, "depends on", NULL, &readl_ff, &readl_00);
  89 }
  90
  91 static void match_return(struct expression *expr)
  92 {
  93
  94         if (__inline_fn)
  95                 return;
  96         returned = 1;
  97 #if 0
  98         struct smatch_state *tmp;
  99
 100         if (!readl_has_been_called)
 101                 return;
 102
 103         FOR_EACH_PTR(state_at_start, tmp) {
 104                 REPLACE_CURRENT_PTR(tmp, NULL);
 105         }
 106 #endif
 107 }
 108
 109 static void push_state_at_start(struct smatch_state *state)
 110 {
 111         add_ptr_list(&state_at_start, state);
 112 }
 113
 114 static struct smatch_state *pop_state_at_start(void)
 115 {
 116         struct smatch_state *state;
 117
 118         state = last_ptr_list((struct ptr_list *)state_at_start);
 119         delete_ptr_list_last((struct ptr_list **)&state_at_start);
 120         return state;
 121 }
 122
 123 static void before_loop(struct statement *stmt)
 124 {
 125         struct smatch_state *state;
 126
 127         if (!stmt || stmt->type != STMT_ITERATOR)
 128                 return;
 129         if (ptr_list_empty(state_at_start))
 130                 returned = 0;
 131         state = get_state(my_id, "depends on", NULL);
 132         push_state_at_start(state);
 133 }
 134
 135 static void after_loop(struct statement *stmt)
 136 {
 137         struct smatch_state *old_state;
 138
 139         if (!stmt || stmt->type != STMT_ITERATOR)
 140                 return;
 141         old_state = pop_state_at_start();
 142         if (old_state == &readl_00)
 143                 return;
 144         if (returned)
 145                 return;
 146         if (get_state(my_id, "depends on", NULL) != &readl_00)
 147                 return;
 148         sm_msg("warn: this loop depends on readl() succeeding");
 149 }
 150
 151 void check_readl_infinite_loops(int id)
 152 {
 153         if (option_project != PROJ_KERNEL)
 154                 return;
 155
 156         my_id = id;
 157
 158         add_hook(match_assign, ASSIGNMENT_HOOK);
 159         add_hook(check_condition, CONDITION_HOOK);
 160
 161         add_hook(&match_return, RETURN_HOOK);
 162
 163         add_hook(before_loop, STMT_HOOK);
 164         add_hook(after_loop, STMT_HOOK_AFTER);
 165 }