perf evlist: Add support for mmapping an AUX area buffer

[mirror_ubuntu-artful-kernel.git] / tools / perf / util / auxtrace.h

/*
 * auxtrace.h: AUX area trace support
 * Copyright (c) 2013-2015, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 */

#ifndef __PERF_AUXTRACE_H
#define __PERF_AUXTRACE_H

#include <sys/types.h>
#include <stdbool.h>

#include <linux/perf_event.h>
#include <linux/types.h>

#include "../perf.h"

struct perf_evlist;

/**
 * struct auxtrace_mmap - records an mmap of the auxtrace buffer.
 * @base: address of mapped area
 * @userpg: pointer to buffer's perf_event_mmap_page
 * @mask: %0 if @len is not a power of two, otherwise (@len - %1)
 * @len: size of mapped area
 * @prev: previous aux_head
 * @idx: index of this mmap
 * @tid: tid for a per-thread mmap (also set if there is only 1 tid on a per-cpu
 *       mmap) otherwise %0
 * @cpu: cpu number for a per-cpu mmap otherwise %-1
 */
struct auxtrace_mmap {
	void		*base;
	void		*userpg;
	size_t		mask;
	size_t		len;
	u64		prev;
	int		idx;
	pid_t		tid;
	int		cpu;
};

/**
 * struct auxtrace_mmap_params - parameters to set up struct auxtrace_mmap.
 * @mask: %0 if @len is not a power of two, otherwise (@len - %1)
 * @offset: file offset of mapped area
 * @len: size of mapped area
 * @prot: mmap memory protection
 * @idx: index of this mmap
 * @tid: tid for a per-thread mmap (also set if there is only 1 tid on a per-cpu
 *       mmap) otherwise %0
 * @cpu: cpu number for a per-cpu mmap otherwise %-1
 */
struct auxtrace_mmap_params {
	size_t		mask;
	off_t		offset;
	size_t		len;
	int		prot;
	int		idx;
	pid_t		tid;
	int		cpu;
};

static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm)
{
	struct perf_event_mmap_page *pc = mm->userpg;
#if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
	u64 head = ACCESS_ONCE(pc->aux_head);
#else
	u64 head = __sync_val_compare_and_swap(&pc->aux_head, 0, 0);
#endif

	/* Ensure all reads are done after we read the head */
	rmb();
	return head;
}

static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
{
	struct perf_event_mmap_page *pc = mm->userpg;
#if BITS_PER_LONG != 64 && defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
	u64 old_tail;
#endif

	/* Ensure all reads are done before we write the tail out */
	mb();
#if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
	pc->aux_tail = tail;
#else
	do {
		old_tail = __sync_val_compare_and_swap(&pc->aux_tail, 0, 0);
	} while (!__sync_bool_compare_and_swap(&pc->aux_tail, old_tail, tail));
#endif
}

int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,
			struct auxtrace_mmap_params *mp,
			void *userpg, int fd);
void auxtrace_mmap__munmap(struct auxtrace_mmap *mm);
void auxtrace_mmap_params__init(struct auxtrace_mmap_params *mp,
				off_t auxtrace_offset,
				unsigned int auxtrace_pages,
				bool auxtrace_overwrite);
void auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp,
				   struct perf_evlist *evlist, int idx,
				   bool per_cpu);

#endif