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Linux kernel mirror (for testing)
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linux
1/*
2 * Copyright (C) 2016 Red Hat, Inc.
3 * Author: Michael S. Tsirkin <mst@redhat.com>
4 * This work is licensed under the terms of the GNU GPL, version 2.
5 *
6 * Common macros and functions for ring benchmarking.
7 */
8#ifndef MAIN_H
9#define MAIN_H
10
11#include <stdbool.h>
12
13extern int param;
14
15extern bool do_exit;
16
17#if defined(__x86_64__) || defined(__i386__)
18#include "x86intrin.h"
19
20static inline void wait_cycles(unsigned long long cycles)
21{
22 unsigned long long t;
23
24 t = __rdtsc();
25 while (__rdtsc() - t < cycles) {}
26}
27
28#define VMEXIT_CYCLES 500
29#define VMENTRY_CYCLES 500
30
31#elif defined(__s390x__)
32static inline void wait_cycles(unsigned long long cycles)
33{
34 asm volatile("0: brctg %0,0b" : : "d" (cycles));
35}
36
37/* tweak me */
38#define VMEXIT_CYCLES 200
39#define VMENTRY_CYCLES 200
40
41#else
42static inline void wait_cycles(unsigned long long cycles)
43{
44 _Exit(5);
45}
46#define VMEXIT_CYCLES 0
47#define VMENTRY_CYCLES 0
48#endif
49
50static inline void vmexit(void)
51{
52 if (!do_exit)
53 return;
54
55 wait_cycles(VMEXIT_CYCLES);
56}
57static inline void vmentry(void)
58{
59 if (!do_exit)
60 return;
61
62 wait_cycles(VMENTRY_CYCLES);
63}
64
65/* implemented by ring */
66void alloc_ring(void);
67/* guest side */
68int add_inbuf(unsigned, void *, void *);
69void *get_buf(unsigned *, void **);
70void disable_call();
71bool used_empty();
72bool enable_call();
73void kick_available();
74/* host side */
75void disable_kick();
76bool avail_empty();
77bool enable_kick();
78bool use_buf(unsigned *, void **);
79void call_used();
80
81/* implemented by main */
82extern bool do_sleep;
83void kick(void);
84void wait_for_kick(void);
85void call(void);
86void wait_for_call(void);
87
88extern unsigned ring_size;
89
90/* Compiler barrier - similar to what Linux uses */
91#define barrier() asm volatile("" ::: "memory")
92
93/* Is there a portable way to do this? */
94#if defined(__x86_64__) || defined(__i386__)
95#define cpu_relax() asm ("rep; nop" ::: "memory")
96#elif defined(__s390x__)
97#define cpu_relax() barrier()
98#else
99#define cpu_relax() assert(0)
100#endif
101
102extern bool do_relax;
103
104static inline void busy_wait(void)
105{
106 if (do_relax)
107 cpu_relax();
108 else
109 /* prevent compiler from removing busy loops */
110 barrier();
111}
112
113/*
114 * Not using __ATOMIC_SEQ_CST since gcc docs say they are only synchronized
115 * with other __ATOMIC_SEQ_CST calls.
116 */
117#define smp_mb() __sync_synchronize()
118
119/*
120 * This abuses the atomic builtins for thread fences, and
121 * adds a compiler barrier.
122 */
123#define smp_release() do { \
124 barrier(); \
125 __atomic_thread_fence(__ATOMIC_RELEASE); \
126} while (0)
127
128#define smp_acquire() do { \
129 __atomic_thread_fence(__ATOMIC_ACQUIRE); \
130 barrier(); \
131} while (0)
132
133#endif