1 #ifndef _ASM_X86_VGTOD_H 2 #define _ASM_X86_VGTOD_H 3 4 #include <linux/compiler.h> 5 #include <linux/clocksource.h> 6 7 #ifdef BUILD_VDSO32_64 8 typedef u64 gtod_long_t; 9 #else 10 typedef unsigned long gtod_long_t; 11 #endif 12 /* 13 * vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time 14 * so be carefull by modifying this structure. 15 */ 16 struct vsyscall_gtod_data { 17 unsigned seq; 18 19 int vclock_mode; 20 cycle_t cycle_last; 21 cycle_t mask; 22 u32 mult; 23 u32 shift; 24 25 /* open coded 'struct timespec' */ 26 u64 wall_time_snsec; 27 gtod_long_t wall_time_sec; 28 gtod_long_t monotonic_time_sec; 29 u64 monotonic_time_snsec; 30 gtod_long_t wall_time_coarse_sec; 31 gtod_long_t wall_time_coarse_nsec; 32 gtod_long_t monotonic_time_coarse_sec; 33 gtod_long_t monotonic_time_coarse_nsec; 34 35 int tz_minuteswest; 36 int tz_dsttime; 37 }; 38 extern struct vsyscall_gtod_data vsyscall_gtod_data; 39 40 static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s) 41 { 42 unsigned ret; 43 44 repeat: 45 ret = ACCESS_ONCE(s->seq); 46 if (unlikely(ret & 1)) { 47 cpu_relax(); 48 goto repeat; 49 } 50 smp_rmb(); 51 return ret; 52 } 53 54 static inline int gtod_read_retry(const struct vsyscall_gtod_data *s, 55 unsigned start) 56 { 57 smp_rmb(); 58 return unlikely(s->seq != start); 59 } 60 61 static inline void gtod_write_begin(struct vsyscall_gtod_data *s) 62 { 63 ++s->seq; 64 smp_wmb(); 65 } 66 67 static inline void gtod_write_end(struct vsyscall_gtod_data *s) 68 { 69 smp_wmb(); 70 ++s->seq; 71 } 72 73 #ifdef CONFIG_X86_64 74 75 #define VGETCPU_CPU_MASK 0xfff 76 77 static inline unsigned int __getcpu(void) 78 { 79 unsigned int p; 80 81 /* 82 * Load per CPU data from GDT. LSL is faster than RDTSCP and 83 * works on all CPUs. This is volatile so that it orders 84 * correctly wrt barrier() and to keep gcc from cleverly 85 * hoisting it out of the calling function. 86 */ 87 asm volatile ("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG)); 88 89 return p; 90 } 91 92 #endif /* CONFIG_X86_64 */ 93 94 #endif /* _ASM_X86_VGTOD_H */ 95