tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#ifndef _ASM_X86_PVCLOCK_H
2#define _ASM_X86_PVCLOCK_H
3
4#include <linux/clocksource.h>
5#include <asm/pvclock-abi.h>
6
7#ifdef CONFIG_KVM_GUEST
8extern struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void);
9#else
10static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
11{
12 return NULL;
13}
14#endif
15
16/* some helper functions for xen and kvm pv clock sources */
17cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
18u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
19void pvclock_set_flags(u8 flags);
20unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
21void pvclock_read_wallclock(struct pvclock_wall_clock *wall,
22 struct pvclock_vcpu_time_info *vcpu,
23 struct timespec *ts);
24void pvclock_resume(void);
25
26void pvclock_touch_watchdogs(void);
27
28static __always_inline
29unsigned pvclock_read_begin(const struct pvclock_vcpu_time_info *src)
30{
31 unsigned version = src->version & ~1;
32 /* Make sure that the version is read before the data. */
33 virt_rmb();
34 return version;
35}
36
37static __always_inline
38bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src,
39 unsigned version)
40{
41 /* Make sure that the version is re-read after the data. */
42 virt_rmb();
43 return unlikely(version != src->version);
44}
45
46/*
47 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
48 * yielding a 64-bit result.
49 */
50static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift)
51{
52 u64 product;
53#ifdef __i386__
54 u32 tmp1, tmp2;
55#else
56 ulong tmp;
57#endif
58
59 if (shift < 0)
60 delta >>= -shift;
61 else
62 delta <<= shift;
63
64#ifdef __i386__
65 __asm__ (
66 "mul %5 ; "
67 "mov %4,%%eax ; "
68 "mov %%edx,%4 ; "
69 "mul %5 ; "
70 "xor %5,%5 ; "
71 "add %4,%%eax ; "
72 "adc %5,%%edx ; "
73 : "=A" (product), "=r" (tmp1), "=r" (tmp2)
74 : "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );
75#elif defined(__x86_64__)
76 __asm__ (
77 "mulq %[mul_frac] ; shrd $32, %[hi], %[lo]"
78 : [lo]"=a"(product),
79 [hi]"=d"(tmp)
80 : "0"(delta),
81 [mul_frac]"rm"((u64)mul_frac));
82#else
83#error implement me!
84#endif
85
86 return product;
87}
88
89static __always_inline
90cycle_t __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src)
91{
92 u64 delta = rdtsc_ordered() - src->tsc_timestamp;
93 cycle_t offset = pvclock_scale_delta(delta, src->tsc_to_system_mul,
94 src->tsc_shift);
95 return src->system_time + offset;
96}
97
98struct pvclock_vsyscall_time_info {
99 struct pvclock_vcpu_time_info pvti;
100} __attribute__((__aligned__(SMP_CACHE_BYTES)));
101
102#define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
103
104#endif /* _ASM_X86_PVCLOCK_H */