diff options
author | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
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committer | André Fabian Silva Delgado <emulatorman@parabola.nu> | 2015-08-05 17:04:01 -0300 |
commit | 57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch) | |
tree | 5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/x86/include/asm/vgtod.h |
Initial import
Diffstat (limited to 'arch/x86/include/asm/vgtod.h')
-rw-r--r-- | arch/x86/include/asm/vgtod.h | 94 |
1 files changed, 94 insertions, 0 deletions
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h new file mode 100644 index 000000000..f556c4843 --- /dev/null +++ b/arch/x86/include/asm/vgtod.h @@ -0,0 +1,94 @@ +#ifndef _ASM_X86_VGTOD_H +#define _ASM_X86_VGTOD_H + +#include <linux/compiler.h> +#include <linux/clocksource.h> + +#ifdef BUILD_VDSO32_64 +typedef u64 gtod_long_t; +#else +typedef unsigned long gtod_long_t; +#endif +/* + * vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time + * so be carefull by modifying this structure. + */ +struct vsyscall_gtod_data { + unsigned seq; + + int vclock_mode; + cycle_t cycle_last; + cycle_t mask; + u32 mult; + u32 shift; + + /* open coded 'struct timespec' */ + u64 wall_time_snsec; + gtod_long_t wall_time_sec; + gtod_long_t monotonic_time_sec; + u64 monotonic_time_snsec; + gtod_long_t wall_time_coarse_sec; + gtod_long_t wall_time_coarse_nsec; + gtod_long_t monotonic_time_coarse_sec; + gtod_long_t monotonic_time_coarse_nsec; + + int tz_minuteswest; + int tz_dsttime; +}; +extern struct vsyscall_gtod_data vsyscall_gtod_data; + +static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s) +{ + unsigned ret; + +repeat: + ret = ACCESS_ONCE(s->seq); + if (unlikely(ret & 1)) { + cpu_relax(); + goto repeat; + } + smp_rmb(); + return ret; +} + +static inline int gtod_read_retry(const struct vsyscall_gtod_data *s, + unsigned start) +{ + smp_rmb(); + return unlikely(s->seq != start); +} + +static inline void gtod_write_begin(struct vsyscall_gtod_data *s) +{ + ++s->seq; + smp_wmb(); +} + +static inline void gtod_write_end(struct vsyscall_gtod_data *s) +{ + smp_wmb(); + ++s->seq; +} + +#ifdef CONFIG_X86_64 + +#define VGETCPU_CPU_MASK 0xfff + +static inline unsigned int __getcpu(void) +{ + unsigned int p; + + /* + * Load per CPU data from GDT. LSL is faster than RDTSCP and + * works on all CPUs. This is volatile so that it orders + * correctly wrt barrier() and to keep gcc from cleverly + * hoisting it out of the calling function. + */ + asm volatile ("lsl %1,%0" : "=r" (p) : "r" (__PER_CPU_SEG)); + + return p; +} + +#endif /* CONFIG_X86_64 */ + +#endif /* _ASM_X86_VGTOD_H */ |