Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6
[linux-2.6] / 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/gfp.h>
22 #include <linux/mm.h>
23 #include <asm/page.h>
24 #include <xen/xencomm.h>
25 #include <xen/interface/xen.h>
26 #ifdef __ia64__
27 #include <asm/xen/xencomm.h>    /* for is_kern_addr() */
28 #endif
29
30 #ifdef HAVE_XEN_PLATFORM_COMPAT_H
31 #include <xen/platform-compat.h>
32 #endif
33
34 static int xencomm_init(struct xencomm_desc *desc,
35                         void *buffer, unsigned long bytes)
36 {
37         unsigned long recorded = 0;
38         int i = 0;
39
40         while ((recorded < bytes) && (i < desc->nr_addrs)) {
41                 unsigned long vaddr = (unsigned long)buffer + recorded;
42                 unsigned long paddr;
43                 int offset;
44                 int chunksz;
45
46                 offset = vaddr % PAGE_SIZE; /* handle partial pages */
47                 chunksz = min(PAGE_SIZE - offset, bytes - recorded);
48
49                 paddr = xencomm_vtop(vaddr);
50                 if (paddr == ~0UL) {
51                         printk(KERN_DEBUG "%s: couldn't translate vaddr %lx\n",
52                                __func__, vaddr);
53                         return -EINVAL;
54                 }
55
56                 desc->address[i++] = paddr;
57                 recorded += chunksz;
58         }
59
60         if (recorded < bytes) {
61                 printk(KERN_DEBUG
62                        "%s: could only translate %ld of %ld bytes\n",
63                        __func__, recorded, bytes);
64                 return -ENOSPC;
65         }
66
67         /* mark remaining addresses invalid (just for safety) */
68         while (i < desc->nr_addrs)
69                 desc->address[i++] = XENCOMM_INVALID;
70
71         desc->magic = XENCOMM_MAGIC;
72
73         return 0;
74 }
75
76 static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
77                                           void *buffer, unsigned long bytes)
78 {
79         struct xencomm_desc *desc;
80         unsigned long buffer_ulong = (unsigned long)buffer;
81         unsigned long start = buffer_ulong & PAGE_MASK;
82         unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
83         unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
84         unsigned long size = sizeof(*desc) +
85                 sizeof(desc->address[0]) * nr_addrs;
86
87         /*
88          * slab allocator returns at least sizeof(void*) aligned pointer.
89          * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
90          * cross page boundary.
91          */
92         if (sizeof(*desc) > sizeof(void *)) {
93                 unsigned long order = get_order(size);
94                 desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
95                                                                order);
96                 if (desc == NULL)
97                         return NULL;
98
99                 desc->nr_addrs =
100                         ((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
101                         sizeof(*desc->address);
102         } else {
103                 desc = kmalloc(size, gfp_mask);
104                 if (desc == NULL)
105                         return NULL;
106
107                 desc->nr_addrs = nr_addrs;
108         }
109         return desc;
110 }
111
112 void xencomm_free(struct xencomm_handle *desc)
113 {
114         if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
115                 struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
116                 if (sizeof(*desc__) > sizeof(void *)) {
117                         unsigned long size = sizeof(*desc__) +
118                                 sizeof(desc__->address[0]) * desc__->nr_addrs;
119                         unsigned long order = get_order(size);
120                         free_pages((unsigned long)__va(desc), order);
121                 } else
122                         kfree(__va(desc));
123         }
124 }
125
126 static int xencomm_create(void *buffer, unsigned long bytes,
127                           struct xencomm_desc **ret, gfp_t gfp_mask)
128 {
129         struct xencomm_desc *desc;
130         int rc;
131
132         pr_debug("%s: %p[%ld]\n", __func__, buffer, bytes);
133
134         if (bytes == 0) {
135                 /* don't create a descriptor; Xen recognizes NULL. */
136                 BUG_ON(buffer != NULL);
137                 *ret = NULL;
138                 return 0;
139         }
140
141         BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
142
143         desc = xencomm_alloc(gfp_mask, buffer, bytes);
144         if (!desc) {
145                 printk(KERN_DEBUG "%s failure\n", "xencomm_alloc");
146                 return -ENOMEM;
147         }
148
149         rc = xencomm_init(desc, buffer, bytes);
150         if (rc) {
151                 printk(KERN_DEBUG "%s failure: %d\n", "xencomm_init", rc);
152                 xencomm_free((struct xencomm_handle *)__pa(desc));
153                 return rc;
154         }
155
156         *ret = desc;
157         return 0;
158 }
159
160 /* check if memory address is within VMALLOC region  */
161 static int is_phys_contiguous(unsigned long addr)
162 {
163         if (!is_kernel_addr(addr))
164                 return 0;
165
166         return (addr < VMALLOC_START) || (addr >= VMALLOC_END);
167 }
168
169 static struct xencomm_handle *xencomm_create_inline(void *ptr)
170 {
171         unsigned long paddr;
172
173         BUG_ON(!is_phys_contiguous((unsigned long)ptr));
174
175         paddr = (unsigned long)xencomm_pa(ptr);
176         BUG_ON(paddr & XENCOMM_INLINE_FLAG);
177         return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
178 }
179
180 /* "mini" routine, for stack-based communications: */
181 static int xencomm_create_mini(void *buffer,
182         unsigned long bytes, struct xencomm_mini *xc_desc,
183         struct xencomm_desc **ret)
184 {
185         int rc = 0;
186         struct xencomm_desc *desc;
187         BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
188
189         desc = (void *)xc_desc;
190
191         desc->nr_addrs = XENCOMM_MINI_ADDRS;
192
193         rc = xencomm_init(desc, buffer, bytes);
194         if (!rc)
195                 *ret = desc;
196
197         return rc;
198 }
199
200 struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
201 {
202         int rc;
203         struct xencomm_desc *desc;
204
205         if (is_phys_contiguous((unsigned long)ptr))
206                 return xencomm_create_inline(ptr);
207
208         rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
209
210         if (rc || desc == NULL)
211                 return NULL;
212
213         return xencomm_pa(desc);
214 }
215
216 struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
217                         struct xencomm_mini *xc_desc)
218 {
219         int rc;
220         struct xencomm_desc *desc = NULL;
221
222         if (is_phys_contiguous((unsigned long)ptr))
223                 return xencomm_create_inline(ptr);
224
225         rc = xencomm_create_mini(ptr, bytes, xc_desc,
226                                 &desc);
227
228         if (rc)
229                 return NULL;
230
231         return xencomm_pa(desc);
232 }