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/*
* Copyright (C) 2016 Red Hat, Inc.
* Author: Michael S. Tsirkin <mst@redhat.com>
* This work is licensed under the terms of the GNU GPL, version 2.
*
* Common macros and functions for ring benchmarking.
*/
#ifndef MAIN_H
#define MAIN_H
#include <stdbool.h>
extern int param;
extern bool do_exit;
#if defined(__x86_64__) || defined(__i386__)
#include "x86intrin.h"
static inline void wait_cycles(unsigned long long cycles)
{
unsigned long long t;
t = __rdtsc();
while (__rdtsc() - t < cycles) {}
}
#define VMEXIT_CYCLES 500
#define VMENTRY_CYCLES 500
#elif defined(__s390x__)
static inline void wait_cycles(unsigned long long cycles)
{
asm volatile("0: brctg %0,0b" : : "d" (cycles));
}
/* tweak me */
#define VMEXIT_CYCLES 200
#define VMENTRY_CYCLES 200
#else
static inline void wait_cycles(unsigned long long cycles)
{
_Exit(5);
}
#define VMEXIT_CYCLES 0
#define VMENTRY_CYCLES 0
#endif
static inline void vmexit(void)
{
if (!do_exit)
return;
wait_cycles(VMEXIT_CYCLES);
}
static inline void vmentry(void)
{
if (!do_exit)
return;
wait_cycles(VMENTRY_CYCLES);
}
/* implemented by ring */
void alloc_ring(void);
/* guest side */
int add_inbuf(unsigned, void *, void *);
void *get_buf(unsigned *, void **);
void disable_call();
bool used_empty();
bool enable_call();
void kick_available();
/* host side */
void disable_kick();
bool avail_empty();
bool enable_kick();
bool use_buf(unsigned *, void **);
void call_used();
/* implemented by main */
extern bool do_sleep;
void kick(void);
void wait_for_kick(void);
void call(void);
void wait_for_call(void);
extern unsigned ring_size;
/* Compiler barrier - similar to what Linux uses */
#define barrier() asm volatile("" ::: "memory")
/* Is there a portable way to do this? */
#if defined(__x86_64__) || defined(__i386__)
#define cpu_relax() asm ("rep; nop" ::: "memory")
#elif defined(__s390x__)
#define cpu_relax() barrier()
#else
#define cpu_relax() assert(0)
#endif
extern bool do_relax;
static inline void busy_wait(void)
{
if (do_relax)
cpu_relax();
else
/* prevent compiler from removing busy loops */
barrier();
}
#if defined(__x86_64__) || defined(__i386__)
#define smp_mb() asm volatile("lock; addl $0,-132(%%rsp)" ::: "memory", "cc")
#else
/*
* Not using __ATOMIC_SEQ_CST since gcc docs say they are only synchronized
* with other __ATOMIC_SEQ_CST calls.
*/
#define smp_mb() __sync_synchronize()
#endif
/*
* This abuses the atomic builtins for thread fences, and
* adds a compiler barrier.
*/
#define smp_release() do { \
barrier(); \
__atomic_thread_fence(__ATOMIC_RELEASE); \
} while (0)
#define smp_acquire() do { \
__atomic_thread_fence(__ATOMIC_ACQUIRE); \
barrier(); \
} while (0)
#if defined(__i386__) || defined(__x86_64__) || defined(__s390x__)
#define smp_wmb() barrier()
#else
#define smp_wmb() smp_release()
#endif
#ifdef __alpha__
#define smp_read_barrier_depends() smp_acquire()
#else
#define smp_read_barrier_depends() do {} while(0)
#endif
static __always_inline
void __read_once_size(const volatile void *p, void *res, int size)
{
switch (size) { \
case 1: *(unsigned char *)res = *(volatile unsigned char *)p; break; \
case 2: *(unsigned short *)res = *(volatile unsigned short *)p; break; \
case 4: *(unsigned int *)res = *(volatile unsigned int *)p; break; \
case 8: *(unsigned long long *)res = *(volatile unsigned long long *)p; break; \
default: \
barrier(); \
__builtin_memcpy((void *)res, (const void *)p, size); \
barrier(); \
} \
}
static __always_inline void __write_once_size(volatile void *p, void *res, int size)
{
switch (size) {
case 1: *(volatile unsigned char *)p = *(unsigned char *)res; break;
case 2: *(volatile unsigned short *)p = *(unsigned short *)res; break;
case 4: *(volatile unsigned int *)p = *(unsigned int *)res; break;
case 8: *(volatile unsigned long long *)p = *(unsigned long long *)res; break;
default:
barrier();
__builtin_memcpy((void *)p, (const void *)res, size);
barrier();
}
}
#define READ_ONCE(x) \
({ \
union { typeof(x) __val; char __c[1]; } __u; \
__read_once_size(&(x), __u.__c, sizeof(x)); \
smp_read_barrier_depends(); /* Enforce dependency ordering from x */ \
__u.__val; \
})
#define WRITE_ONCE(x, val) \
({ \
union { typeof(x) __val; char __c[1]; } __u = \
{ .__val = (typeof(x)) (val) }; \
__write_once_size(&(x), __u.__c, sizeof(x)); \
__u.__val; \
})
#endif
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