LXR linux/drivers/xen/xencomm.c

   1/*
   2 * This program is free software; you can redistribute it and/or modify
   3 * it under the terms of the GNU General Public License as published by
   4 * the Free Software Foundation; either version 2 of the License, or
   5 * (at your option) any later version.
   6 *
   7 * This program is distributed in the hope that it will be useful,
   8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10 * GNU General Public License for more details.
  11 *
  12 * You should have received a copy of the GNU General Public License
  13 * along with this program; if not, write to the Free Software
  14 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  15 *
  16 * Copyright (C) IBM Corp. 2006
  17 *
  18 * Authors: Hollis Blanchard <hollisb@us.ibm.com>
  19 */
  20
  21#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  22
  23#include <linux/mm.h>
  24#include <linux/slab.h>
  25#include <asm/page.h>
  26#include <xen/xencomm.h>
  27#include <xen/interface/xen.h>
  28#include <asm/xen/xencomm.h>    /* for xencomm_is_phys_contiguous() */
  29
  30static int xencomm_init(struct xencomm_desc *desc,
  31                        void *buffer, unsigned long bytes)
  32{
  33        unsigned long recorded = 0;
  34        int i = 0;
  35
  36        while ((recorded < bytes) && (i < desc->nr_addrs)) {
  37                unsigned long vaddr = (unsigned long)buffer + recorded;
  38                unsigned long paddr;
  39                int offset;
  40                int chunksz;
  41
  42                offset = vaddr % PAGE_SIZE; /* handle partial pages */
  43                chunksz = min(PAGE_SIZE - offset, bytes - recorded);
  44
  45                paddr = xencomm_vtop(vaddr);
  46                if (paddr == ~0UL) {
  47                        printk(KERN_DEBUG "%s: couldn't translate vaddr %lx\n",
  48                               __func__, vaddr);
  49                        return -EINVAL;
  50                }
  51
  52                desc->address[i++] = paddr;
  53                recorded += chunksz;
  54        }
  55
  56        if (recorded < bytes) {
  57                printk(KERN_DEBUG
  58                       "%s: could only translate %ld of %ld bytes\n",
  59                       __func__, recorded, bytes);
  60                return -ENOSPC;
  61        }
  62
  63        /* mark remaining addresses invalid (just for safety) */
  64        while (i < desc->nr_addrs)
  65                desc->address[i++] = XENCOMM_INVALID;
  66
  67        desc->magic = XENCOMM_MAGIC;
  68
  69        return 0;
  70}
  71
  72static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
  73                                          void *buffer, unsigned long bytes)
  74{
  75        struct xencomm_desc *desc;
  76        unsigned long buffer_ulong = (unsigned long)buffer;
  77        unsigned long start = buffer_ulong & PAGE_MASK;
  78        unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
  79        unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
  80        unsigned long size = sizeof(*desc) +
  81                sizeof(desc->address[0]) * nr_addrs;
  82
  83        /*
  84         * slab allocator returns at least sizeof(void*) aligned pointer.
  85         * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
  86         * cross page boundary.
  87         */
  88        if (sizeof(*desc) > sizeof(void *)) {
  89                unsigned long order = get_order(size);
  90                desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
  91                                                               order);
  92                if (desc == NULL)
  93                        return NULL;
  94
  95                desc->nr_addrs =
  96                        ((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
  97                        sizeof(*desc->address);
  98        } else {
  99                desc = kmalloc(size, gfp_mask);
 100                if (desc == NULL)
 101                        return NULL;
 102
 103                desc->nr_addrs = nr_addrs;
 104        }
 105        return desc;
 106}
 107
 108void xencomm_free(struct xencomm_handle *desc)
 109{
 110        if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
 111                struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
 112                if (sizeof(*desc__) > sizeof(void *)) {
 113                        unsigned long size = sizeof(*desc__) +
 114                                sizeof(desc__->address[0]) * desc__->nr_addrs;
 115                        unsigned long order = get_order(size);
 116                        free_pages((unsigned long)__va(desc), order);
 117                } else
 118                        kfree(__va(desc));
 119        }
 120}
 121
 122static int xencomm_create(void *buffer, unsigned long bytes,
 123                          struct xencomm_desc **ret, gfp_t gfp_mask)
 124{
 125        struct xencomm_desc *desc;
 126        int rc;
 127
 128        pr_debug("%s: %p[%ld]\n", __func__, buffer, bytes);
 129
 130        if (bytes == 0) {
 131                /* don't create a descriptor; Xen recognizes NULL. */
 132                BUG_ON(buffer != NULL);
 133                *ret = NULL;
 134                return 0;
 135        }
 136
 137        BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
 138
 139        desc = xencomm_alloc(gfp_mask, buffer, bytes);
 140        if (!desc) {
 141                printk(KERN_DEBUG "%s failure\n", "xencomm_alloc");
 142                return -ENOMEM;
 143        }
 144
 145        rc = xencomm_init(desc, buffer, bytes);
 146        if (rc) {
 147                printk(KERN_DEBUG "%s failure: %d\n", "xencomm_init", rc);
 148                xencomm_free((struct xencomm_handle *)__pa(desc));
 149                return rc;
 150        }
 151
 152        *ret = desc;
 153        return 0;
 154}
 155
 156static struct xencomm_handle *xencomm_create_inline(void *ptr)
 157{
 158        unsigned long paddr;
 159
 160        BUG_ON(!xencomm_is_phys_contiguous((unsigned long)ptr));
 161
 162        paddr = (unsigned long)xencomm_pa(ptr);
 163        BUG_ON(paddr & XENCOMM_INLINE_FLAG);
 164        return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
 165}
 166
 167/* "mini" routine, for stack-based communications: */
 168static int xencomm_create_mini(void *buffer,
 169        unsigned long bytes, struct xencomm_mini *xc_desc,
 170        struct xencomm_desc **ret)
 171{
 172        int rc = 0;
 173        struct xencomm_desc *desc;
 174        BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
 175
 176        desc = (void *)xc_desc;
 177
 178        desc->nr_addrs = XENCOMM_MINI_ADDRS;
 179
 180        rc = xencomm_init(desc, buffer, bytes);
 181        if (!rc)
 182                *ret = desc;
 183
 184        return rc;
 185}
 186
 187struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
 188{
 189        int rc;
 190        struct xencomm_desc *desc;
 191
 192        if (xencomm_is_phys_contiguous((unsigned long)ptr))
 193                return xencomm_create_inline(ptr);
 194
 195        rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
 196
 197        if (rc || desc == NULL)
 198                return NULL;
 199
 200        return xencomm_pa(desc);
 201}
 202
 203struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
 204                        struct xencomm_mini *xc_desc)
 205{
 206        int rc;
 207        struct xencomm_desc *desc = NULL;
 208
 209        if (xencomm_is_phys_contiguous((unsigned long)ptr))
 210                return xencomm_create_inline(ptr);
 211
 212        rc = xencomm_create_mini(ptr, bytes, xc_desc,
 213                                &desc);
 214
 215        if (rc)
 216                return NULL;
 217
 218        return xencomm_pa(desc);
 219}
 220