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bpf: add ring_buffer.h drop in replacement header

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Add fast variant for x86-64 for now, and we can later extend for
others upon demand.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Daniel Borkmann 2018-10-19 23:09:07 +02:00
parent 62706e5557
commit a0e4e323bb
1 changed files with 51 additions and 0 deletions
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51
include/linux/ring_buffer.h Normal file
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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
#ifndef _TOOLS_LINUX_RING_BUFFER_H_
#define _TOOLS_LINUX_RING_BUFFER_H_
#define READ_ONCE(x) (*(volatile typeof(x) *)&x)
#define WRITE_ONCE(x, v) (*(volatile typeof(x) *)&x) = (v)
#define barrier() asm volatile("" ::: "memory")
#if defined(__x86_64__)
# define smp_store_release(p, v) \
do { \
barrier(); \
WRITE_ONCE(*p, v); \
} while (0)
# define smp_load_acquire(p) \
({ \
typeof(*p) ___p = READ_ONCE(*p); \
barrier(); \
___p; \
})
#else
# define smp_mb() __sync_synchronize()
# define smp_store_release(p, v) \
do { \
smp_mb(); \
WRITE_ONCE(*p, v); \
} while (0)
# define smp_load_acquire(p) \
({ \
typeof(*p) ___p = READ_ONCE(*p); \
smp_mb(); \
___p; \
})
#endif /* defined(__x86_64__) */
static inline __u64 ring_buffer_read_head(struct perf_event_mmap_page *base)
{
return smp_load_acquire(&base->data_head);
}
static inline void ring_buffer_write_tail(struct perf_event_mmap_page *base,
__u64 tail)
{
smp_store_release(&base->data_tail, tail);
}
#endif /* _TOOLS_LINUX_RING_BUFFER_H_ */