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 #include <linux/mm.h>
  22 #include <linux/slab.h>
  23 #include <asm/page.h>
  24 #include <xen/xencomm.h>
  25 #include <xen/interface/xen.h>
  26 #include <asm/xen/xencomm.h>    /* for xencomm_is_phys_contiguous() */
  27
  28 static int xencomm_init(struct xencomm_desc *desc,
  29                         void *buffer, unsigned long bytes)
  30 {
  31         unsigned long recorded = 0;
  32         int i = 0;
  33
  34         while ((recorded < bytes) && (i < desc->nr_addrs)) {
  35                 unsigned long vaddr = (unsigned long)buffer + recorded;
  36                 unsigned long paddr;
  37                 int offset;
  38                 int chunksz;
  39
  40                 offset = vaddr % PAGE_SIZE; /* handle partial pages */
  41                 chunksz = min(PAGE_SIZE - offset, bytes - recorded);
  42
  43                 paddr = xencomm_vtop(vaddr);
  44                 if (paddr == ~0UL) {
  45                         printk(KERN_DEBUG "%s: couldn't translate vaddr %lx\n",
  46                                __func__, vaddr);
  47                         return -EINVAL;
  48                 }
  49
  50                 desc->address[i++] = paddr;
  51                 recorded += chunksz;
  52         }
  53
  54         if (recorded < bytes) {
  55                 printk(KERN_DEBUG
  56                        "%s: could only translate %ld of %ld bytes\n",
  57                        __func__, recorded, bytes);
  58                 return -ENOSPC;
  59         }
  60
  61         /* mark remaining addresses invalid (just for safety) */
  62         while (i < desc->nr_addrs)
  63                 desc->address[i++] = XENCOMM_INVALID;
  64
  65         desc->magic = XENCOMM_MAGIC;
  66
  67         return 0;
  68 }
  69
  70 static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
  71                                           void *buffer, unsigned long bytes)
  72 {
  73         struct xencomm_desc *desc;
  74         unsigned long buffer_ulong = (unsigned long)buffer;
  75         unsigned long start = buffer_ulong & PAGE_MASK;
  76         unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
  77         unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
  78         unsigned long size = sizeof(*desc) +
  79                 sizeof(desc->address[0]) * nr_addrs;
  80
  81         /*
  82          * slab allocator returns at least sizeof(void*) aligned pointer.
  83          * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
  84          * cross page boundary.
  85          */
  86         if (sizeof(*desc) > sizeof(void *)) {
  87                 unsigned long order = get_order(size);
  88                 desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
  89                                                                order);
  90                 if (desc == NULL)
  91                         return NULL;
  92
  93                 desc->nr_addrs =
  94                         ((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
  95                         sizeof(*desc->address);
  96         } else {
  97                 desc = kmalloc(size, gfp_mask);
  98                 if (desc == NULL)
  99                         return NULL;
 100
 101                 desc->nr_addrs = nr_addrs;
 102         }
 103         return desc;
 104 }
 105
 106 void xencomm_free(struct xencomm_handle *desc)
 107 {
 108         if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
 109                 struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
 110                 if (sizeof(*desc__) > sizeof(void *)) {
 111                         unsigned long size = sizeof(*desc__) +
 112                                 sizeof(desc__->address[0]) * desc__->nr_addrs;
 113                         unsigned long order = get_order(size);
 114                         free_pages((unsigned long)__va(desc), order);
 115                 } else
 116                         kfree(__va(desc));
 117         }
 118 }
 119
 120 static int xencomm_create(void *buffer, unsigned long bytes,
 121                           struct xencomm_desc **ret, gfp_t gfp_mask)
 122 {
 123         struct xencomm_desc *desc;
 124         int rc;
 125
 126         pr_debug("%s: %p[%ld]\n", __func__, buffer, bytes);
 127
 128         if (bytes == 0) {
 129                 /* don't create a descriptor; Xen recognizes NULL. */
 130                 BUG_ON(buffer != NULL);
 131                 *ret = NULL;
 132                 return 0;
 133         }
 134
 135         BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
 136
 137         desc = xencomm_alloc(gfp_mask, buffer, bytes);
 138         if (!desc) {
 139                 printk(KERN_DEBUG "%s failure\n", "xencomm_alloc");
 140                 return -ENOMEM;
 141         }
 142
 143         rc = xencomm_init(desc, buffer, bytes);
 144         if (rc) {
 145                 printk(KERN_DEBUG "%s failure: %d\n", "xencomm_init", rc);
 146                 xencomm_free((struct xencomm_handle *)__pa(desc));
 147                 return rc;
 148         }
 149
 150         *ret = desc;
 151         return 0;
 152 }
 153
 154 static struct xencomm_handle *xencomm_create_inline(void *ptr)
 155 {
 156         unsigned long paddr;
 157
 158         BUG_ON(!xencomm_is_phys_contiguous((unsigned long)ptr));
 159
 160         paddr = (unsigned long)xencomm_pa(ptr);
 161         BUG_ON(paddr & XENCOMM_INLINE_FLAG);
 162         return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
 163 }
 164
 165 /* "mini" routine, for stack-based communications: */
 166 static int xencomm_create_mini(void *buffer,
 167         unsigned long bytes, struct xencomm_mini *xc_desc,
 168         struct xencomm_desc **ret)
 169 {
 170         int rc = 0;
 171         struct xencomm_desc *desc;
 172         BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
 173
 174         desc = (void *)xc_desc;
 175
 176         desc->nr_addrs = XENCOMM_MINI_ADDRS;
 177
 178         rc = xencomm_init(desc, buffer, bytes);
 179         if (!rc)
 180                 *ret = desc;
 181
 182         return rc;
 183 }
 184
 185 struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
 186 {
 187         int rc;
 188         struct xencomm_desc *desc;
 189
 190         if (xencomm_is_phys_contiguous((unsigned long)ptr))
 191                 return xencomm_create_inline(ptr);
 192
 193         rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
 194
 195         if (rc || desc == NULL)
 196                 return NULL;
 197
 198         return xencomm_pa(desc);
 199 }
 200
 201 struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
 202                         struct xencomm_mini *xc_desc)
 203 {
 204         int rc;
 205         struct xencomm_desc *desc = NULL;
 206
 207         if (xencomm_is_phys_contiguous((unsigned long)ptr))
 208                 return xencomm_create_inline(ptr);
 209
 210         rc = xencomm_create_mini(ptr, bytes, xc_desc,
 211                                 &desc);
 212
 213         if (rc)
 214                 return NULL;
 215
 216         return xencomm_pa(desc);
 217 }