barrier.h 1.8 KB

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  1. #ifndef _ASM_UM_BARRIER_H_
  2. #define _ASM_UM_BARRIER_H_
  3. #include <asm/asm.h>
  4. #include <asm/segment.h>
  5. #include <asm/cpufeature.h>
  6. #include <asm/cmpxchg.h>
  7. #include <asm/nops.h>
  8. #include <linux/kernel.h>
  9. #include <linux/irqflags.h>
  10. /*
  11. * Force strict CPU ordering.
  12. * And yes, this is required on UP too when we're talking
  13. * to devices.
  14. */
  15. #ifdef CONFIG_X86_32
  16. #define mb() alternative("lock; addl $0,0(%%esp)", "mfence", X86_FEATURE_XMM2)
  17. #define rmb() alternative("lock; addl $0,0(%%esp)", "lfence", X86_FEATURE_XMM2)
  18. #define wmb() alternative("lock; addl $0,0(%%esp)", "sfence", X86_FEATURE_XMM)
  19. #else /* CONFIG_X86_32 */
  20. #define mb() asm volatile("mfence" : : : "memory")
  21. #define rmb() asm volatile("lfence" : : : "memory")
  22. #define wmb() asm volatile("sfence" : : : "memory")
  23. #endif /* CONFIG_X86_32 */
  24. #ifdef CONFIG_X86_PPRO_FENCE
  25. #define dma_rmb() rmb()
  26. #else /* CONFIG_X86_PPRO_FENCE */
  27. #define dma_rmb() barrier()
  28. #endif /* CONFIG_X86_PPRO_FENCE */
  29. #define dma_wmb() barrier()
  30. #ifdef CONFIG_SMP
  31. #define smp_mb() mb()
  32. #define smp_rmb() dma_rmb()
  33. #define smp_wmb() barrier()
  34. #define set_mb(var, value) do { (void)xchg(&var, value); } while (0)
  35. #else /* CONFIG_SMP */
  36. #define smp_mb() barrier()
  37. #define smp_rmb() barrier()
  38. #define smp_wmb() barrier()
  39. #define set_mb(var, value) do { var = value; barrier(); } while (0)
  40. #endif /* CONFIG_SMP */
  41. #define read_barrier_depends() do { } while (0)
  42. #define smp_read_barrier_depends() do { } while (0)
  43. /*
  44. * Stop RDTSC speculation. This is needed when you need to use RDTSC
  45. * (or get_cycles or vread that possibly accesses the TSC) in a defined
  46. * code region.
  47. *
  48. * (Could use an alternative three way for this if there was one.)
  49. */
  50. static inline void rdtsc_barrier(void)
  51. {
  52. alternative(ASM_NOP3, "mfence", X86_FEATURE_MFENCE_RDTSC);
  53. alternative(ASM_NOP3, "lfence", X86_FEATURE_LFENCE_RDTSC);
  54. }
  55. #endif