check_spectre_second_half.c

   1 /*
   2  * Copyright (C) 2018 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 #include "smatch_slist.h"
  21
  22 /* New chips will probably be able to speculate further ahead */
  23 #define MAX_SPEC_STMT 200
  24
  25 static int my_id;
  26
  27 struct stree *first_halfs;
  28
  29 struct expression *recently_set;
  30
  31 void set_spectre_first_half(struct expression *expr)
  32 {
  33         char buf[64];
  34         char *name;
  35
  36         name = expr_to_str(expr);
  37         snprintf(buf, sizeof(buf), "%p %s", expr, name);
  38         free_string(name);
  39
  40         set_state_stree(&first_halfs, my_id, buf, NULL, alloc_state_num(get_stmt_cnt()));
  41 }
  42
  43 void clear_spectre_second_halfs(void)
  44 {
  45         struct sm_state *sm;
  46
  47         FOR_EACH_MY_SM(my_id, __get_cur_stree(), sm) {
  48                 set_state(my_id, sm->name, sm->sym, alloc_state_num(-MAX_SPEC_STMT));
  49         } END_FOR_EACH_SM(sm);
  50 }
  51
  52 static struct smatch_state *get_spectre_first_half(struct expression *expr)
  53 {
  54         char buf[64];
  55         char *name;
  56
  57         name = expr_to_str(expr);
  58         snprintf(buf, sizeof(buf), "%p %s", expr, name);
  59         free_string(name);
  60
  61         return get_state_stree(first_halfs, my_id, buf, NULL);
  62 }
  63
  64 static void match_assign(struct expression *expr)
  65 {
  66         struct smatch_state *state;
  67
  68         if (expr->op == SPECIAL_AND_ASSIGN)
  69                 return;
  70
  71         state = get_spectre_first_half(expr->right);
  72         if (state) {
  73                 set_state_expr(my_id, expr->left, state);
  74                 recently_set = expr->left;
  75                 return;
  76         }
  77         state = get_state_expr(my_id, expr->right);
  78         if (!state)
  79                 return;
  80         set_state_expr(my_id, expr->left, state);
  81         recently_set = expr->left;
  82 }
  83
  84 static void match_done(struct expression *expr)
  85 {
  86         struct smatch_state *state;
  87         char *name;
  88
  89         if (expr == recently_set)
  90                 return;
  91
  92         state = get_state_expr(my_id, expr);
  93         if (!state)
  94                 return;
  95
  96         if (get_stmt_cnt() - (long)state->data > MAX_SPEC_STMT)
  97                 return;
  98
  99         name = expr_to_str(expr);
 100         sm_msg("warn: possible spectre second half.  '%s'", name);
 101         free_string(name);
 102
 103         set_state_expr(my_id, expr, alloc_state_num(-MAX_SPEC_STMT));
 104 }
 105
 106 static void match_end_func(struct symbol *sym)
 107 {
 108         if (__inline_fn)
 109                 return;
 110         free_stree(&first_halfs);
 111 }
 112
 113 void check_spectre_second_half(int id)
 114 {
 115         my_id = id;
 116
 117         if (option_project != PROJ_KERNEL)
 118                 return;
 119         set_dynamic_states(my_id);
 120         add_hook(&match_assign, ASSIGNMENT_HOOK);
 121         add_hook(&match_done, SYM_HOOK);
 122         add_hook(&match_done, DEREF_HOOK);
 123
 124         add_hook(&match_end_func, END_FUNC_HOOK);
 125 }