Edit File: gpt.h
/* * Copyright 2016 Red Hat Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that 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. * * Authors: Jérôme Glisse <jglisse@redhat.com> */ /* * Generic page table structure with adjustable depth. This is unlike regular * CPU page table use on many architecture. It is more like radix tree but it * uses full pages and offers more bits for flags per entry. * * Note that resizing it (increase its depth) is something relatively easy to * add in case someone cares. * * Note that we use the private field of root struct page to store the number * of levels as well as the pfn_shift values. Moreover we use _mapcount field * to count number of valid entry inside each directory. */ #ifndef _LINUX_GPT_H #define _LINUX_GPT_H #include <linux/mm_types.h> #include <linux/spinlock.h> #include <linux/gfp.h> #ifdef CONFIG_HIGHMEM64G #define gte_t uint64_t #else /* CONFIG_HIGHMEM64G */ #define gte_t unsigned long #endif /* CONFIG_HIGHMEM64G */ /* 6 level on 64 bits arch with PAGE_SHIFT=12 means 66bits of address space */ #define GPT_MAX_LEVEL 6 struct gpt { unsigned long start; unsigned long end; unsigned long *gdp; atomic_t refcount; spinlock_t lock; uint8_t nlevels; uint8_t shift; uint8_t valid_bit; }; struct gpt *gpt_alloc(unsigned long start, unsigned long end, uint8_t shift, uint8_t valid_bit); void gpt_free(struct gpt *gpt); struct gpt_walk { struct gpt *gpt; unsigned long start; unsigned long end; struct page *gtd[GPT_MAX_LEVEL]; gte_t *gte[GPT_MAX_LEVEL]; }; void gpt_walk_init(struct gpt_walk *walk, struct gpt *gpt); void gpt_walk_fini(struct gpt_walk *walk); gte_t *gpt_walk_gtep_from_addr(struct gpt_walk *walk, unsigned long addr); gte_t *gpt_walk_populate(struct gpt_walk *walk, unsigned long addr); void gpt_walk_prune(struct gpt_walk *walk, unsigned long start, unsigned long end); typedef int (*gpt_walk_cb_t)(struct gpt_walk *walk, unsigned long addr, unsigned long end, spinlock_t *gtl, gte_t *gtep, void *private); int gpt_walk_range(struct gpt_walk *walk, unsigned long start, unsigned long end, gpt_walk_cb_t cb, void *private); /* gpt_walk_gtd_refcount - pointer to atomic use to count valid directory entry * @walk: walk structure from which to extract directory level * @level: level for the refcount (0 is the lowest level) * Returns: pointer to refcount atomic or NULL if directory level is empty * * To know when we can prune (free) a directory we count number of valid entry * and this for all directory levels. */ static inline atomic_t *gpt_walk_gtd_refcount(struct gpt_walk *walk, unsigned level) { BUG_ON(level > walk->gpt->nlevels); if (walk->gpt->nlevels && (level < walk->gpt->nlevels)) { if (walk->gtd[level]) return &walk->gtd[level]->_mapcount; return NULL; } return &walk->gpt->refcount; } /* gpt_walk_gtd_lock_ptr - spinlock pointer for given directory level * @walk: walk structure with current directory hierarchy * @level: level to lock (0 is the lowest level and gpt->nlevels the highest) * Returns: spinlock pointer for given level, NULL if directory level is empty * * To provide fine granularity locking to generic page table we use the struct * page spinlock. This helper just provide a pointer to the appropriate lock * for a given directory level. */ static inline spinlock_t *gpt_walk_gtd_lock_ptr(struct gpt_walk *walk, unsigned level) { BUG_ON(level > walk->gpt->nlevels); if (walk->gpt->nlevels && (level < walk->gpt->nlevels)) { if (walk->gtd[level]) return ptlock_ptr(walk->gtd[level]); return NULL; } return &walk->gpt->lock; } #endif /* _LINUX_GPT_H */