iPXE
initrd.c
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1 /*
2  * Copyright (C) 2012 Michael Brown <mbrown@fensystems.co.uk>.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation; either version 2 of the
7  * License, or (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17  * 02110-1301, USA.
18  *
19  * You can also choose to distribute this program under the terms of
20  * the Unmodified Binary Distribution Licence (as given in the file
21  * COPYING.UBDL), provided that you have satisfied its requirements.
22  */
23 
24 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
25 
26 #include <errno.h>
27 #include <initrd.h>
28 #include <ipxe/image.h>
29 #include <ipxe/uaccess.h>
30 #include <ipxe/init.h>
31 #include <ipxe/memblock.h>
32 
33 /** @file
34  *
35  * Initial ramdisk (initrd) reshuffling
36  *
37  */
38 
39 /** Maximum address available for initrd */
41 
42 /** Minimum address available for initrd */
44 
45 /**
46  * Squash initrds as high as possible in memory
47  *
48  * @v top Highest possible address
49  * @ret used Lowest address used by initrds
50  */
52  userptr_t current = top;
53  struct image *initrd;
54  struct image *highest;
55  size_t len;
56 
57  /* Squash up any initrds already within or below the region */
58  while ( 1 ) {
59 
60  /* Find the highest image not yet in its final position */
61  highest = NULL;
62  for_each_image ( initrd ) {
63  if ( ( userptr_sub ( initrd->data, current ) < 0 ) &&
64  ( ( highest == NULL ) ||
65  ( userptr_sub ( initrd->data,
66  highest->data ) > 0 ) ) ) {
67  highest = initrd;
68  }
69  }
70  if ( ! highest )
71  break;
72 
73  /* Move this image to its final position */
74  len = ( ( highest->len + INITRD_ALIGN - 1 ) &
75  ~( INITRD_ALIGN - 1 ) );
76  current = userptr_sub ( current, len );
77  DBGC ( &images, "INITRD squashing %s [%#08lx,%#08lx)->"
78  "[%#08lx,%#08lx)\n", highest->name,
79  user_to_phys ( highest->data, 0 ),
80  user_to_phys ( highest->data, highest->len ),
81  user_to_phys ( current, 0 ),
82  user_to_phys ( current, highest->len ) );
83  memmove_user ( current, 0, highest->data, 0, highest->len );
84  highest->data = current;
85  }
86 
87  /* Copy any remaining initrds (e.g. embedded images) to the region */
88  for_each_image ( initrd ) {
89  if ( userptr_sub ( initrd->data, top ) >= 0 ) {
90  len = ( ( initrd->len + INITRD_ALIGN - 1 ) &
91  ~( INITRD_ALIGN - 1 ) );
92  current = userptr_sub ( current, len );
93  DBGC ( &images, "INITRD copying %s [%#08lx,%#08lx)->"
94  "[%#08lx,%#08lx)\n", initrd->name,
95  user_to_phys ( initrd->data, 0 ),
96  user_to_phys ( initrd->data, initrd->len ),
97  user_to_phys ( current, 0 ),
98  user_to_phys ( current, initrd->len ) );
99  memcpy_user ( current, 0, initrd->data, 0,
100  initrd->len );
101  initrd->data = current;
102  }
103  }
104 
105  return current;
106 }
107 
108 /**
109  * Swap position of two adjacent initrds
110  *
111  * @v low Lower initrd
112  * @v high Higher initrd
113  * @v free Free space
114  * @v free_len Length of free space
115  */
116 static void initrd_swap ( struct image *low, struct image *high,
117  userptr_t free, size_t free_len ) {
118  size_t len = 0;
119  size_t frag_len;
120  size_t new_len;
121 
122  DBGC ( &images, "INITRD swapping %s [%#08lx,%#08lx)<->[%#08lx,%#08lx) "
123  "%s\n", low->name, user_to_phys ( low->data, 0 ),
124  user_to_phys ( low->data, low->len ),
125  user_to_phys ( high->data, 0 ),
126  user_to_phys ( high->data, high->len ), high->name );
127 
128  /* Round down length of free space */
129  free_len &= ~( INITRD_ALIGN - 1 );
130  assert ( free_len > 0 );
131 
132  /* Swap image data */
133  while ( len < high->len ) {
134 
135  /* Calculate maximum fragment length */
136  frag_len = ( high->len - len );
137  if ( frag_len > free_len )
138  frag_len = free_len;
139  new_len = ( ( len + frag_len + INITRD_ALIGN - 1 ) &
140  ~( INITRD_ALIGN - 1 ) );
141 
142  /* Swap fragments */
143  memcpy_user ( free, 0, high->data, len, frag_len );
144  memmove_user ( low->data, new_len, low->data, len, low->len );
145  memcpy_user ( low->data, len, free, 0, frag_len );
146  len = new_len;
147  }
148 
149  /* Adjust data pointers */
150  high->data = low->data;
151  low->data = userptr_add ( low->data, len );
152 }
153 
154 /**
155  * Swap position of any two adjacent initrds not currently in the correct order
156  *
157  * @v free Free space
158  * @v free_len Length of free space
159  * @ret swapped A pair of initrds was swapped
160  */
161 static int initrd_swap_any ( userptr_t free, size_t free_len ) {
162  struct image *low;
163  struct image *high;
164  size_t padded_len;
165  userptr_t adjacent;
166 
167  /* Find any pair of initrds that can be swapped */
168  for_each_image ( low ) {
169 
170  /* Calculate location of adjacent image (if any) */
171  padded_len = ( ( low->len + INITRD_ALIGN - 1 ) &
172  ~( INITRD_ALIGN - 1 ) );
173  adjacent = userptr_add ( low->data, padded_len );
174 
175  /* Search for adjacent image */
176  for_each_image ( high ) {
177 
178  /* If we have found the adjacent image, swap and exit */
179  if ( high->data == adjacent ) {
180  initrd_swap ( low, high, free, free_len );
181  return 1;
182  }
183 
184  /* Stop search if all remaining potential
185  * adjacent images are already in the correct
186  * order.
187  */
188  if ( high == low )
189  break;
190  }
191  }
192 
193  /* Nothing swapped */
194  return 0;
195 }
196 
197 /**
198  * Dump initrd locations (for debug)
199  *
200  */
201 static void initrd_dump ( void ) {
202  struct image *initrd;
203 
204  /* Do nothing unless debugging is enabled */
205  if ( ! DBG_LOG )
206  return;
207 
208  /* Dump initrd locations */
209  for_each_image ( initrd ) {
210  DBGC ( &images, "INITRD %s at [%#08lx,%#08lx)\n",
211  initrd->name, user_to_phys ( initrd->data, 0 ),
212  user_to_phys ( initrd->data, initrd->len ) );
213  DBGC2_MD5A ( &images, user_to_phys ( initrd->data, 0 ),
214  user_to_virt ( initrd->data, 0 ), initrd->len );
215  }
216 }
217 
218 /**
219  * Reshuffle initrds into desired order at top of memory
220  *
221  * @v bottom Lowest address available for initrds
222  *
223  * After this function returns, the initrds have been rearranged in
224  * memory and the external heap structures will have been corrupted.
225  * Reshuffling must therefore take place immediately prior to jumping
226  * to the loaded OS kernel; no further execution within iPXE is
227  * permitted.
228  */
230  userptr_t top;
231  userptr_t used;
232  userptr_t free;
233  size_t free_len;
234 
235  /* Calculate limits of available space for initrds */
236  top = initrd_top;
237  if ( userptr_sub ( initrd_bottom, bottom ) > 0 )
239 
240  /* Debug */
241  DBGC ( &images, "INITRD region [%#08lx,%#08lx)\n",
242  user_to_phys ( bottom, 0 ), user_to_phys ( top, 0 ) );
243  initrd_dump();
244 
245  /* Squash initrds as high as possible in memory */
246  used = initrd_squash_high ( top );
247 
248  /* Calculate available free space */
249  free = bottom;
250  free_len = userptr_sub ( used, free );
251 
252  /* Bubble-sort initrds into desired order */
253  while ( initrd_swap_any ( free, free_len ) ) {}
254 
255  /* Debug */
256  initrd_dump();
257 }
258 
259 /**
260  * Check that there is enough space to reshuffle initrds
261  *
262  * @v len Total length of initrds (including padding)
263  * @v bottom Lowest address available for initrds
264  * @ret rc Return status code
265  */
267  userptr_t top;
268  size_t available;
269 
270  /* Calculate limits of available space for initrds */
271  top = initrd_top;
272  if ( userptr_sub ( initrd_bottom, bottom ) > 0 )
274  available = userptr_sub ( top, bottom );
275 
276  /* Allow for a sensible minimum amount of free space */
278 
279  /* Check for available space */
280  return ( ( len < available ) ? 0 : -ENOBUFS );
281 }
282 
283 /**
284  * initrd startup function
285  *
286  */
287 static void initrd_startup ( void ) {
288  size_t len;
289 
290  /* Record largest memory block available. Do this after any
291  * allocations made during driver startup (e.g. large host
292  * memory blocks for Infiniband devices, which may still be in
293  * use at the time of rearranging if a SAN device is hooked)
294  * but before any allocations for downloaded images (which we
295  * can safely reuse when rearranging).
296  */
299 }
300 
301 /** initrd startup function */
302 struct startup_fn startup_initrd __startup_fn ( STARTUP_LATE ) = {
303  .name = "initrd",
304  .startup = initrd_startup,
305 };
static void initrd_swap(struct image *low, struct image *high, userptr_t free, size_t free_len)
Swap position of two adjacent initrds.
Definition: initrd.c:116
static int initrd_swap_any(userptr_t free, size_t free_len)
Swap position of any two adjacent initrds not currently in the correct order.
Definition: initrd.c:161
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)
userptr_t data
Raw file image.
Definition: image.h:41
userptr_t initrd_bottom
Minimum address available for initrd.
Definition: initrd.c:43
Error codes.
unsigned long user_to_phys(userptr_t userptr, off_t offset)
Convert user pointer to physical address.
#define INITRD_MIN_FREE_LEN
Minimum free space required to reshuffle initrds.
Definition: initrd.h:25
#define DBGC(...)
Definition: compiler.h:505
void initrd_reshuffle(userptr_t bottom)
Reshuffle initrds into desired order at top of memory.
Definition: initrd.c:229
static userptr_t bottom
Bottom of heap (current lowest allocated block)
An executable image.
Definition: image.h:24
#define DBGC2_MD5A(...)
Definition: compiler.h:525
const char * name
Definition: init.h:42
struct startup_fn startup_initrd __startup_fn(STARTUP_LATE)
initrd startup function
Access to external ("user") memory.
Largest memory block.
#define STARTUP_LATE
Late startup.
Definition: init.h:64
#define INITRD_ALIGN
Minimum alignment for initrds.
Definition: initrd.h:19
off_t userptr_sub(userptr_t userptr, userptr_t subtrahend)
Subtract user pointers.
A startup/shutdown function.
Definition: init.h:41
userptr_t userptr_add(userptr_t userptr, off_t offset)
Add offset to user pointer.
userptr_t initrd_top
Maximum address available for initrd.
Definition: initrd.c:40
assert((readw(&hdr->flags) &(GTF_reading|GTF_writing))==0)
Executable images.
static void initrd_dump(void)
Dump initrd locations (for debug)
Definition: initrd.c:201
uint32_t low
Low 16 bits of address.
Definition: intel.h:21
#define for_each_image(image)
Iterate over all registered images.
Definition: image.h:149
static void(* free)(struct refcnt *refcnt))
Definition: refcnt.h:54
size_t len
Length of raw file image.
Definition: image.h:43
static userptr_t top
Top of heap.
struct list_head images
List of registered images.
Definition: image.c:56
static void initrd_startup(void)
initrd startup function
Definition: initrd.c:287
Initial ramdisk (initrd) reshuffling.
static userptr_t initrd_squash_high(userptr_t top)
Squash initrds as high as possible in memory.
Definition: initrd.c:51
uint32_t len
Length.
Definition: ena.h:14
#define ENOBUFS
No buffer space available.
Definition: errno.h:498
int initrd_reshuffle_check(size_t len, userptr_t bottom)
Check that there is enough space to reshuffle initrds.
Definition: initrd.c:266
void * user_to_virt(userptr_t userptr, off_t offset)
Convert user pointer to virtual address.
size_t largest_memblock(userptr_t *start)
Find largest usable memory region.
void memmove_user(userptr_t dest, off_t dest_off, userptr_t src, off_t src_off, size_t len)
Copy data between user buffers, allowing for overlap.
uint32_t high
High 32 bits of address.
Definition: intel.h:22
#define DBG_LOG
Definition: compiler.h:317
char * name
Name.
Definition: image.h:34
#define NULL
NULL pointer (VOID *)
Definition: Base.h:362
void memcpy_user(userptr_t dest, off_t dest_off, userptr_t src, off_t src_off, size_t len)
Copy data between user buffers.
unsigned long userptr_t
A pointer to a user buffer.
Definition: uaccess.h:33