1 /* SPDX-License-Identifier: GPL-2.0 */ 2 #ifndef _ASM_X86_VGTOD_H 3 #define _ASM_X86_VGTOD_H 4 5 #include <linux/compiler.h> 6 #include <linux/clocksource.h> 7 8 #include <uapi/linux/time.h> 9 10 #ifdef BUILD_VDSO32_64 11 typedef u64 gtod_long_t; 12 #else 13 typedef unsigned long gtod_long_t; 14 #endif 15 16 struct vgtod_ts { 17 u64 sec; 18 u64 nsec; 19 }; 20 21 #define VGTOD_BASES (CLOCK_MONOTONIC_COARSE + 1) 22 #define VGTOD_HRES (BIT(CLOCK_REALTIME) | BIT(CLOCK_MONOTONIC)) 23 #define VGTOD_COARSE (BIT(CLOCK_REALTIME_COARSE) | BIT(CLOCK_MONOTONIC_COARSE)) 24 25 /* 26 * vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time 27 * so be carefull by modifying this structure. 28 */ 29 struct vsyscall_gtod_data { 30 unsigned int seq; 31 32 int vclock_mode; 33 u64 cycle_last; 34 u64 mask; 35 u32 mult; 36 u32 shift; 37 38 struct vgtod_ts basetime[VGTOD_BASES]; 39 40 int tz_minuteswest; 41 int tz_dsttime; 42 }; 43 extern struct vsyscall_gtod_data vsyscall_gtod_data; 44 45 extern int vclocks_used; 46 static inline bool vclock_was_used(int vclock) 47 { 48 return READ_ONCE(vclocks_used) & (1 << vclock); 49 } 50 51 static inline unsigned int gtod_read_begin(const struct vsyscall_gtod_data *s) 52 { 53 unsigned int ret; 54 55 repeat: 56 ret = READ_ONCE(s->seq); 57 if (unlikely(ret & 1)) { 58 cpu_relax(); 59 goto repeat; 60 } 61 smp_rmb(); 62 return ret; 63 } 64 65 static inline int gtod_read_retry(const struct vsyscall_gtod_data *s, 66 unsigned int start) 67 { 68 smp_rmb(); 69 return unlikely(s->seq != start); 70 } 71 72 static inline void gtod_write_begin(struct vsyscall_gtod_data *s) 73 { 74 ++s->seq; 75 smp_wmb(); 76 } 77 78 static inline void gtod_write_end(struct vsyscall_gtod_data *s) 79 { 80 smp_wmb(); 81 ++s->seq; 82 } 83 84 #ifdef CONFIG_X86_64 85 86 #define VGETCPU_CPU_MASK 0xfff 87 88 static inline unsigned int __getcpu(void) 89 { 90 unsigned int p; 91 92 /* 93 * Load per CPU data from GDT. LSL is faster than RDTSCP and 94 * works on all CPUs. This is volatile so that it orders 95 * correctly wrt barrier() and to keep gcc from cleverly 96 * hoisting it out of the calling function. 97 * 98 * If RDPID is available, use it. 99 */ 100 alternative_io ("lsl %[seg],%[p]", 101 ".byte 0xf3,0x0f,0xc7,0xf8", /* RDPID %eax/rax */ 102 X86_FEATURE_RDPID, 103 [p] "=a" (p), [seg] "r" (__PER_CPU_SEG)); 104 105 return p; 106 } 107 108 #endif /* CONFIG_X86_64 */ 109 110 #endif /* _ASM_X86_VGTOD_H */ 111