check_readl_infinite_loops.c

   1 /*
   2  * smatch/check_readl_hotplug.c
   3  *
   4  * Copyright (C) 2014 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11 #include "smatch_extra.h"
  12
  13 static int my_id;
  14
  15 STATE(readl);
  16 STATE(readl_ff);
  17 STATE(readl_00);
  18
  19 DECLARE_PTR_LIST(state_stack, struct smatch_state);
  20 struct state_stack *state_at_start;
  21
  22 static int readl_has_been_called;
  23 static int returned;
  24
  25 static int is_readl_call(struct expression *expr)
  26 {
  27         struct symbol *sym;
  28
  29         expr = strip_expr(expr);
  30         if (expr->type != EXPR_CALL)
  31                 return 0;
  32         if (expr->fn->type != EXPR_SYMBOL)
  33                 return 0;
  34         sym = expr->fn->symbol;
  35         if (!sym || !sym->ident)
  36                 return 0;
  37         if (strcmp(sym->ident->name, "readl") != 0)
  38                 return 0;
  39         return 1;
  40 }
  41
  42 static int is_readl(struct expression *expr)
  43 {
  44         if (is_readl_call(expr))
  45                 return 1;
  46         if (get_state_expr(my_id, expr) == &readl)
  47                 return 1;
  48         return 0;
  49 }
  50
  51 static void match_assign(struct expression *expr)
  52 {
  53         if (is_readl(expr->right))
  54                 set_state_expr(my_id, expr->left, &readl);
  55         else if (get_state_expr(my_id, expr->left))
  56                 set_state_expr(my_id, expr->left, &undefined);
  57 }
  58
  59 static int condition_depends_on_readl(struct expression *expr)
  60 {
  61         if (expr->type == EXPR_BINOP) {
  62                 if (condition_depends_on_readl(expr->left))
  63                         return 1;
  64                 if (condition_depends_on_readl(expr->right))
  65                         return 1;
  66                 return 0;
  67         }
  68         if (is_readl(expr))
  69                 return 1;
  70         return 0;
  71 }
  72
  73 static void check_condition(struct expression *expr)
  74 {
  75         if (expr->op != '&')
  76                 return;
  77         if (!condition_depends_on_readl(expr))
  78                 return;
  79         readl_has_been_called = 1;
  80         set_true_false_states(my_id, "depends on", NULL, &readl_ff, &readl_00);
  81 }
  82
  83 static void match_return(struct expression *expr)
  84 {
  85
  86         if (__inline_fn)
  87                 return;
  88         returned = 1;
  89 #if 0
  90         struct smatch_state *tmp;
  91
  92         if (!readl_has_been_called)
  93                 return;
  94
  95         FOR_EACH_PTR(state_at_start, tmp) {
  96                 REPLACE_CURRENT_PTR(tmp, NULL);
  97         }
  98 #endif
  99 }
 100
 101 static void push_state_at_start(struct smatch_state *state)
 102 {
 103         add_ptr_list(&state_at_start, state);
 104 }
 105
 106 static struct smatch_state *pop_state_at_start(void)
 107 {
 108         struct smatch_state *state;
 109
 110         state = last_ptr_list((struct ptr_list *)state_at_start);
 111         delete_ptr_list_last((struct ptr_list **)&state_at_start);
 112         return state;
 113 }
 114
 115 static void before_loop(struct statement *stmt)
 116 {
 117         struct smatch_state *state;
 118
 119         if (!stmt || stmt->type != STMT_ITERATOR)
 120                 return;
 121         if (ptr_list_empty(state_at_start))
 122                 returned = 0;
 123         state = get_state(my_id, "depends on", NULL);
 124         push_state_at_start(state);
 125 }
 126
 127 static void after_loop(struct statement *stmt)
 128 {
 129         struct smatch_state *old_state;
 130
 131         if (!stmt || stmt->type != STMT_ITERATOR)
 132                 return;
 133         old_state = pop_state_at_start();
 134         if (old_state == &readl_00)
 135                 return;
 136         if (returned)
 137                 return;
 138         if (get_state(my_id, "depends on", NULL) != &readl_00)
 139                 return;
 140         sm_msg("warn: this loop depends on readl() succeeding");
 141 }
 142
 143 void check_readl_infinite_loops(int id)
 144 {
 145         if (option_project != PROJ_KERNEL)
 146                 return;
 147
 148         my_id = id;
 149
 150         add_hook(match_assign, ASSIGNMENT_HOOK);
 151         add_hook(check_condition, CONDITION_HOOK);
 152
 153         add_hook(&match_return, RETURN_HOOK);
 154
 155         add_hook(before_loop, STMT_HOOK);
 156         add_hook(after_loop, STMT_HOOK_AFTER);
 157 }