7c03156f34
This patch add the VDSO time support for the IA32 Emulation Layer. Due the nature of the kernel headers and the LP64 compiler where the size of a long and a pointer differs against a 32 bit compiler, there is some type hacking necessary for optimal performance. The vsyscall_gtod_data struture must be a rearranged to serve 32- and 64-bit code access at the same time: - The seqcount_t was replaced by an unsigned, this makes the vsyscall_gtod_data intedepend of kernel configuration and internal functions. - All kernel internal structures are replaced by fix size elements which works for 32- and 64-bit access - The inner struct clock was removed to pack the whole struct. The "unsigned seq" would be handled by functions derivated from seqcount_t. Signed-off-by: Stefani Seibold <stefani@seibold.net> Link: http://lkml.kernel.org/r/1395094933-14252-11-git-send-email-stefani@seibold.net Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
73 lines
1.4 KiB
C
73 lines
1.4 KiB
C
#ifndef _ASM_X86_VGTOD_H
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#define _ASM_X86_VGTOD_H
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#include <linux/compiler.h>
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#include <linux/clocksource.h>
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#ifdef BUILD_VDSO32_64
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typedef u64 gtod_long_t;
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#else
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typedef unsigned long gtod_long_t;
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#endif
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/*
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* vsyscall_gtod_data will be accessed by 32 and 64 bit code at the same time
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* so be carefull by modifying this structure.
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*/
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struct vsyscall_gtod_data {
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unsigned seq;
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int vclock_mode;
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cycle_t cycle_last;
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cycle_t mask;
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u32 mult;
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u32 shift;
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/* open coded 'struct timespec' */
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u64 wall_time_snsec;
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gtod_long_t wall_time_sec;
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gtod_long_t monotonic_time_sec;
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u64 monotonic_time_snsec;
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gtod_long_t wall_time_coarse_sec;
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gtod_long_t wall_time_coarse_nsec;
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gtod_long_t monotonic_time_coarse_sec;
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gtod_long_t monotonic_time_coarse_nsec;
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int tz_minuteswest;
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int tz_dsttime;
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};
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extern struct vsyscall_gtod_data vsyscall_gtod_data;
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static inline unsigned gtod_read_begin(const struct vsyscall_gtod_data *s)
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{
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unsigned ret;
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repeat:
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ret = ACCESS_ONCE(s->seq);
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if (unlikely(ret & 1)) {
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cpu_relax();
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goto repeat;
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}
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smp_rmb();
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return ret;
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}
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static inline int gtod_read_retry(const struct vsyscall_gtod_data *s,
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unsigned start)
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{
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smp_rmb();
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return unlikely(s->seq != start);
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}
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static inline void gtod_write_begin(struct vsyscall_gtod_data *s)
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{
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++s->seq;
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smp_wmb();
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}
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static inline void gtod_write_end(struct vsyscall_gtod_data *s)
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{
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smp_wmb();
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++s->seq;
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}
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#endif /* _ASM_X86_VGTOD_H */
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