spinlock.c 2.4 KB

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  1. /*
  2. * Copyright (C) 2011-2017 Intel Corporation. All rights reserved.
  3. *
  4. * Redistribution and use in source and binary forms, with or without
  5. * modification, are permitted provided that the following conditions
  6. * are met:
  7. *
  8. * * Redistributions of source code must retain the above copyright
  9. * notice, this list of conditions and the following disclaimer.
  10. * * Redistributions in binary form must reproduce the above copyright
  11. * notice, this list of conditions and the following disclaimer in
  12. * the documentation and/or other materials provided with the
  13. * distribution.
  14. * * Neither the name of Intel Corporation nor the names of its
  15. * contributors may be used to endorse or promote products derived
  16. * from this software without specific prior written permission.
  17. *
  18. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  19. * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  20. * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  21. * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22. * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23. * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  24. * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25. * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26. * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27. * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28. * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29. *
  30. */
  31. #include <sgx_spinlock.h>
  32. static inline void _mm_pause(void) __attribute__((always_inline));
  33. static inline int _InterlockedExchange(int volatile * dst, int val) __attribute__((always_inline));
  34. static inline void _mm_pause(void)
  35. {
  36. __asm __volatile(
  37. "pause"
  38. );
  39. }
  40. static inline int _InterlockedExchange(int volatile * dst, int val)
  41. {
  42. int res;
  43. __asm __volatile(
  44. "lock xchg %2, %1;"
  45. "mov %2, %0"
  46. : "=m" (res)
  47. : "m" (*dst),
  48. "r" (val)
  49. : "memory"
  50. );
  51. return (res);
  52. }
  53. uint32_t sgx_spin_lock(sgx_spinlock_t *lock)
  54. {
  55. while(_InterlockedExchange((volatile int *)lock, 1) != 0) {
  56. while (*lock) {
  57. /* tell cpu we are spinning */
  58. _mm_pause();
  59. }
  60. }
  61. return (0);
  62. }
  63. uint32_t sgx_spin_unlock(sgx_spinlock_t *lock)
  64. {
  65. *lock = 0;
  66. return (0);
  67. }