/*-
 *   BSD LICENSE
 *
 *   Copyright(c) 2010-2015 Intel Corporation. All rights reserved.
 *   All rights reserved.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following conditions
 *   are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *     * Neither the name of Intel Corporation nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#define _LARGEFILE64_SOURCE
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/user.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <pthread.h>

#include "spdk/vtophys.h"

/* x86-64 userspace virtual addresses use only the low 47 bits [0..46],
 * which is enough to cover 128 TB.
 */
#define SHIFT_128TB	47 /* (1 << 47) == 128 TB */
#define MASK_128TB	((1ULL << SHIFT_128TB) - 1)

#define SHIFT_1GB	30 /* (1 << 30) == 1 GB */
#define MASK_1GB	((1ULL << SHIFT_1GB) - 1)

#define SHIFT_2MB	21 /* (1 << 21) == 2MB */
#define MASK_2MB	((1ULL << SHIFT_2MB) - 1)

#define SHIFT_4KB	12 /* (1 << 12) == 4KB */
#define MASK_4KB	((1ULL << SHIFT_4KB) - 1)

#define FN_2MB_TO_4KB(fn)	(fn << (SHIFT_2MB - SHIFT_4KB))
#define FN_4KB_TO_2MB(fn)	(fn >> (SHIFT_2MB - SHIFT_4KB))

#define MAP_128TB_IDX(vfn_2mb)	((vfn_2mb) >> (SHIFT_1GB - SHIFT_2MB))
#define MAP_1GB_IDX(vfn_2mb)	((vfn_2mb) & ((1ULL << (SHIFT_1GB - SHIFT_2MB + 1)) - 1))

/* Defines related to Linux pagemap. */
#define PAGEMAP_PFN_MASK	0x007FFFFFFFFFFFFFULL /* bits 54:0 */

/* Defines related to Linux kpageflags. */
#define KPAGEFLAGS_HUGE		17

/* Physical page frame number of a single 2MB page. */
struct map_2mb {
	uint64_t pfn_2mb;
};

/* Second-level map table indexed by bits [21..29] of the virtual address.
 * Each entry contains the 2MB physical page frame number or VTOPHYS_ERROR for entries that haven't
 * been retrieved yet.
 */
struct map_1gb {
	struct map_2mb map[1ULL << (SHIFT_1GB - SHIFT_2MB + 1)];
};

/* Top-level map table indexed by bits [30..46] of the virtual address.
 * Each entry points to a second-level map table or NULL.
 */
struct map_128tb {
	struct map_1gb *map[1ULL << (SHIFT_128TB - SHIFT_1GB + 1)];
};

static struct map_128tb vtophys_map_128tb = {};
static pthread_mutex_t vtophys_mutex = PTHREAD_MUTEX_INITIALIZER;

static struct map_2mb *
vtophys_get_map(uint64_t vfn_2mb)
{
	struct map_1gb *map_1gb;
	struct map_2mb *map_2mb;
	uint64_t idx_128tb = MAP_128TB_IDX(vfn_2mb);
	uint64_t idx_1gb = MAP_1GB_IDX(vfn_2mb);

	if (vfn_2mb & ~MASK_128TB) {
		printf("invalid usermode virtual address\n");
		return NULL;
	}

	map_1gb = vtophys_map_128tb.map[idx_128tb];

	if (!map_1gb) {
		pthread_mutex_lock(&vtophys_mutex);

		/* Recheck to make sure nobody else got the mutex first. */
		map_1gb = vtophys_map_128tb.map[idx_128tb];
		if (!map_1gb) {
			map_1gb = malloc(sizeof(struct map_1gb));
			/* initialize all entries to all 0xFF (VTOPHYS_ERROR) */
			memset(map_1gb, 0xFF, sizeof(struct map_1gb));
			vtophys_map_128tb.map[idx_128tb] = map_1gb;
		}

		pthread_mutex_unlock(&vtophys_mutex);

		if (!map_1gb) {
			printf("allocation failed\n");
			return NULL;
		}
	}

	map_2mb = &map_1gb->map[idx_1gb];
	return map_2mb;
}

uint64_t
vtophys_get_pfn_2mb(uint64_t vfn_2mb)
{
	off64_t offset;
	uint64_t pfn_4kb, pfn_2mb, pfn_flag_info;
	static __thread int fd = -1;
	static __thread int kpageflag_fd = -1;

	if (fd == -1) {
		fd = open("/proc/self/pagemap", O_RDONLY);
		if (fd == -1) {
			perror("pagemap open failed");
			return VTOPHYS_ERROR;
		}
	}

	/*
	 * pagemap has a separate 8 byte entry for each 4KB
	 * page.  So even though we are only storing a single
	 * PFN for every 2MB VFN, we have to get the 4KB
	 * VFN equivalent to lseek into the pagemap.
	 *
	 * vfn contains the 2MB virtual frame number, but we
	 * we need the 4KB equivalent to lseek into the pagemap.
	 * So do a left shift to convert the 2MB vfn to the
	 * 4KB vfn equivalent.
	 */
	offset = FN_2MB_TO_4KB(vfn_2mb) * sizeof(uint64_t);

	if (lseek64(fd, offset, SEEK_SET) < 0) {
		perror("pagemap llseek failed");
		return VTOPHYS_ERROR;
	}

	if (read(fd, &pfn_4kb, sizeof(pfn_4kb)) != sizeof(pfn_4kb)) {
		perror("pagemap read failed");
		return VTOPHYS_ERROR;
	}

	pfn_4kb &= PAGEMAP_PFN_MASK;

	if (kpageflag_fd == -1) {
		kpageflag_fd = open("/proc/kpageflags", O_RDONLY);
		if (kpageflag_fd == -1) {
			perror("kpageflags open failed");
			return VTOPHYS_ERROR;
		}
	}

	offset = pfn_4kb * sizeof(uint64_t);
	if (lseek64(kpageflag_fd, offset, SEEK_SET) < 0) {
		perror("kpageflags llseek failed");
		return VTOPHYS_ERROR;
	}

	if (read(kpageflag_fd, &pfn_flag_info, sizeof(pfn_flag_info)) != sizeof(pfn_flag_info)) {
		perror("kpageflags read failed");
		return VTOPHYS_ERROR;
	}

	/* check whether it is a huge page */
	if (!(pfn_flag_info & (1ULL << KPAGEFLAGS_HUGE))) {
		printf("This is not a huge page\n");
		return VTOPHYS_ERROR;
	}

	pfn_2mb = FN_4KB_TO_2MB(pfn_4kb);
	return pfn_2mb;
}

uint64_t
vtophys(void *buf)
{
	struct map_2mb *map_2mb;
	uint64_t vfn_2mb, pfn_2mb;

	vfn_2mb = (uint64_t)buf;
	vfn_2mb >>= SHIFT_2MB;

	map_2mb = vtophys_get_map(vfn_2mb);
	if (!map_2mb) {
		return VTOPHYS_ERROR;
	}

	pfn_2mb = map_2mb->pfn_2mb;
	if (pfn_2mb == VTOPHYS_ERROR) {
		pfn_2mb = vtophys_get_pfn_2mb(vfn_2mb);
		if (pfn_2mb == VTOPHYS_ERROR) {
			return VTOPHYS_ERROR;
		}
		map_2mb->pfn_2mb = pfn_2mb;
	}

	return (pfn_2mb << SHIFT_2MB) | ((uint64_t)buf & MASK_2MB);
}