cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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pagelist.c (4119B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/module.h>
      3#include <linux/gfp.h>
      4#include <linux/slab.h>
      5#include <linux/pagemap.h>
      6#include <linux/highmem.h>
      7#include <linux/ceph/pagelist.h>
      8
      9struct ceph_pagelist *ceph_pagelist_alloc(gfp_t gfp_flags)
     10{
     11	struct ceph_pagelist *pl;
     12
     13	pl = kmalloc(sizeof(*pl), gfp_flags);
     14	if (!pl)
     15		return NULL;
     16
     17	INIT_LIST_HEAD(&pl->head);
     18	pl->mapped_tail = NULL;
     19	pl->length = 0;
     20	pl->room = 0;
     21	INIT_LIST_HEAD(&pl->free_list);
     22	pl->num_pages_free = 0;
     23	refcount_set(&pl->refcnt, 1);
     24
     25	return pl;
     26}
     27EXPORT_SYMBOL(ceph_pagelist_alloc);
     28
     29static void ceph_pagelist_unmap_tail(struct ceph_pagelist *pl)
     30{
     31	if (pl->mapped_tail) {
     32		struct page *page = list_entry(pl->head.prev, struct page, lru);
     33		kunmap(page);
     34		pl->mapped_tail = NULL;
     35	}
     36}
     37
     38void ceph_pagelist_release(struct ceph_pagelist *pl)
     39{
     40	if (!refcount_dec_and_test(&pl->refcnt))
     41		return;
     42	ceph_pagelist_unmap_tail(pl);
     43	while (!list_empty(&pl->head)) {
     44		struct page *page = list_first_entry(&pl->head, struct page,
     45						     lru);
     46		list_del(&page->lru);
     47		__free_page(page);
     48	}
     49	ceph_pagelist_free_reserve(pl);
     50	kfree(pl);
     51}
     52EXPORT_SYMBOL(ceph_pagelist_release);
     53
     54static int ceph_pagelist_addpage(struct ceph_pagelist *pl)
     55{
     56	struct page *page;
     57
     58	if (!pl->num_pages_free) {
     59		page = __page_cache_alloc(GFP_NOFS);
     60	} else {
     61		page = list_first_entry(&pl->free_list, struct page, lru);
     62		list_del(&page->lru);
     63		--pl->num_pages_free;
     64	}
     65	if (!page)
     66		return -ENOMEM;
     67	pl->room += PAGE_SIZE;
     68	ceph_pagelist_unmap_tail(pl);
     69	list_add_tail(&page->lru, &pl->head);
     70	pl->mapped_tail = kmap(page);
     71	return 0;
     72}
     73
     74int ceph_pagelist_append(struct ceph_pagelist *pl, const void *buf, size_t len)
     75{
     76	while (pl->room < len) {
     77		size_t bit = pl->room;
     78		int ret;
     79
     80		memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK),
     81		       buf, bit);
     82		pl->length += bit;
     83		pl->room -= bit;
     84		buf += bit;
     85		len -= bit;
     86		ret = ceph_pagelist_addpage(pl);
     87		if (ret)
     88			return ret;
     89	}
     90
     91	memcpy(pl->mapped_tail + (pl->length & ~PAGE_MASK), buf, len);
     92	pl->length += len;
     93	pl->room -= len;
     94	return 0;
     95}
     96EXPORT_SYMBOL(ceph_pagelist_append);
     97
     98/* Allocate enough pages for a pagelist to append the given amount
     99 * of data without without allocating.
    100 * Returns: 0 on success, -ENOMEM on error.
    101 */
    102int ceph_pagelist_reserve(struct ceph_pagelist *pl, size_t space)
    103{
    104	if (space <= pl->room)
    105		return 0;
    106	space -= pl->room;
    107	space = (space + PAGE_SIZE - 1) >> PAGE_SHIFT;   /* conv to num pages */
    108
    109	while (space > pl->num_pages_free) {
    110		struct page *page = __page_cache_alloc(GFP_NOFS);
    111		if (!page)
    112			return -ENOMEM;
    113		list_add_tail(&page->lru, &pl->free_list);
    114		++pl->num_pages_free;
    115	}
    116	return 0;
    117}
    118EXPORT_SYMBOL(ceph_pagelist_reserve);
    119
    120/* Free any pages that have been preallocated. */
    121int ceph_pagelist_free_reserve(struct ceph_pagelist *pl)
    122{
    123	while (!list_empty(&pl->free_list)) {
    124		struct page *page = list_first_entry(&pl->free_list,
    125						     struct page, lru);
    126		list_del(&page->lru);
    127		__free_page(page);
    128		--pl->num_pages_free;
    129	}
    130	BUG_ON(pl->num_pages_free);
    131	return 0;
    132}
    133EXPORT_SYMBOL(ceph_pagelist_free_reserve);
    134
    135/* Create a truncation point. */
    136void ceph_pagelist_set_cursor(struct ceph_pagelist *pl,
    137			      struct ceph_pagelist_cursor *c)
    138{
    139	c->pl = pl;
    140	c->page_lru = pl->head.prev;
    141	c->room = pl->room;
    142}
    143EXPORT_SYMBOL(ceph_pagelist_set_cursor);
    144
    145/* Truncate a pagelist to the given point. Move extra pages to reserve.
    146 * This won't sleep.
    147 * Returns: 0 on success,
    148 *          -EINVAL if the pagelist doesn't match the trunc point pagelist
    149 */
    150int ceph_pagelist_truncate(struct ceph_pagelist *pl,
    151			   struct ceph_pagelist_cursor *c)
    152{
    153	struct page *page;
    154
    155	if (pl != c->pl)
    156		return -EINVAL;
    157	ceph_pagelist_unmap_tail(pl);
    158	while (pl->head.prev != c->page_lru) {
    159		page = list_entry(pl->head.prev, struct page, lru);
    160		/* move from pagelist to reserve */
    161		list_move_tail(&page->lru, &pl->free_list);
    162		++pl->num_pages_free;
    163	}
    164	pl->room = c->room;
    165	if (!list_empty(&pl->head)) {
    166		page = list_entry(pl->head.prev, struct page, lru);
    167		pl->mapped_tail = kmap(page);
    168	}
    169	return 0;
    170}
    171EXPORT_SYMBOL(ceph_pagelist_truncate);