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
  30 static 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
  72 static 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
 108 void 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
 122 static 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
 156 static 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: */
 168 static 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
 187 struct 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
 203 struct 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 }