hphp/runtime/vm/jit/vm-protect.h

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-present Facebook, Inc. (http://www.facebook.com)  |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16
  17 #pragma once
  18
  19 #include "hphp/runtime/vm/vm-regs.h"
  20
  21 namespace HPHP { namespace jit {
  22
  23 /*
  24  * RAII assertion guard that ensures VM state (specifically, all of RDS,
  25  * including vmfp, vmsp, and vmpc) is not modified while it is in
  26  * scope. VMProtect::Pause may be used if the protection should be temporarily
  27  * disabled within a scope.
  28  *
  29  * The only rule for nesting is that no VMProtect structs may be constructed
  30  * inside a scope containing a VMProtect::Pause struct. The scope containing
  31  * the VMProtect::Pause struct may contain 0 or more VMProtect structs,
  32  * although only the outermost VMProtect struct will do any real work.
  33  */
  34 struct VMProtect {
  35   struct Pause {
  36 #ifndef NDEBUG
  37     Pause();
  38     ~Pause();
  39 #else
  40     Pause() {}
  41 #endif
  42   };
  43
  44   static __thread bool is_protected;
  45
  46 #ifndef NDEBUG
  47   VMProtect();
  48   ~VMProtect();
  49
  50 private:
  51   void* m_oldBase;
  52   VMRegState m_oldState;
  53 #else
  54   VMProtect() {}
  55 #endif
  56 };
  57
  58 }}