source: rtems/bsps/powerpc/shared/start/sbrk.c @ 9964895

5
Last change on this file since 9964895 was 9964895, checked in by Sebastian Huber <sebastian.huber@…>, on Apr 20, 2018 at 8:35:35 AM

bsps: Move startup files to bsps

Adjust build support files to new directory layout.

This patch is a part of the BSP source reorganization.

Update #3285.

  • Property mode set to 100644
File size: 4.6 KB
Line 
1/*
2 *  sbrk.c
3 *
4 * Authorship
5 * ----------
6 * This software was created by
7 *     Till Straumann <strauman@slac.stanford.edu>, 2002,
8 *        Stanford Linear Accelerator Center, Stanford University.
9 *
10 * Acknowledgement of sponsorship
11 * ------------------------------
12 * This software was produced by
13 *     the Stanford Linear Accelerator Center, Stanford University,
14 *        under Contract DE-AC03-76SFO0515 with the Department of Energy.
15 *
16 * Government disclaimer of liability
17 * ----------------------------------
18 * Neither the United States nor the United States Department of Energy,
19 * nor any of their employees, makes any warranty, express or implied, or
20 * assumes any legal liability or responsibility for the accuracy,
21 * completeness, or usefulness of any data, apparatus, product, or process
22 * disclosed, or represents that its use would not infringe privately owned
23 * rights.
24 *
25 * Stanford disclaimer of liability
26 * --------------------------------
27 * Stanford University makes no representations or warranties, express or
28 * implied, nor assumes any liability for the use of this software.
29 *
30 * Stanford disclaimer of copyright
31 * --------------------------------
32 * Stanford University, owner of the copyright, hereby disclaims its
33 * copyright and all other rights in this software.  Hence, anyone may
34 * freely use it for any purpose without restriction.
35 *
36 * Maintenance of notices
37 * ----------------------
38 * In the interest of clarity regarding the origin and status of this
39 * SLAC software, this and all the preceding Stanford University notices
40 * are to remain affixed to any copy or derivative of this software made
41 * or distributed by the recipient and are to be affixed to any copy of
42 * software made or distributed by the recipient that contains a copy or
43 * derivative of this software.
44 *
45 * ------------------ SLAC Software Notices, Set 4 OTT.002a, 2004 FEB 03
46 */
47
48/*
49 *  Hack around the 32bit powerpc 32M problem:
50 *
51 *  GCC by default uses relative branches which can not jump
52 *  farther than 32M. Hence all program text is confined to
53 *  a single 32M segment.
54 *  This hack gives the RTEMS malloc region all memory below
55 *  32M at startup. Only when this region is exhausted will sbrk
56 *  add more memory. Loading modules may fail at that point, hence
57 *  the user is expected to load all modules at startup _prior_
58 *  to malloc()ing lots of memory...
59 *
60 *  NOTE: it would probably be better to have a separate region
61 *        for module code.
62 */
63
64#include <errno.h>
65#include <unistd.h>
66
67#include <bsp/bootcard.h>
68
69#define INVALID_REMAINING_START ((uintptr_t) -1)
70
71static uintptr_t remaining_start = INVALID_REMAINING_START;
72static uintptr_t remaining_size = 0;
73
74/* App. may provide a value by defining the BSP_sbrk_policy
75 * variable.
76 *
77 *  (-1) -> give all memory to the heap at initialization time
78 *  > 0  -> value used as sbrk amount; initially give 32M
79 *    0  -> limit memory effectively to 32M.
80 *
81 */
82extern uintptr_t        BSP_sbrk_policy[] __attribute__((weak));
83
84#define LIMIT_32M  0x02000000
85
86ptrdiff_t bsp_sbrk_init(Heap_Area *area, uintptr_t min_size)
87{
88  uintptr_t         rval = 0;
89  uintptr_t         policy;
90  uintptr_t         remaining_end;
91
92  remaining_start = (uintptr_t) area->begin;
93  remaining_size  = area->size;
94  remaining_end   = remaining_start + remaining_size;
95
96  if (remaining_start < LIMIT_32M &&
97      remaining_end > LIMIT_32M &&
98      min_size <= LIMIT_32M - remaining_start) {
99    /* clip at LIMIT_32M */
100    rval = remaining_end - LIMIT_32M;
101    area->size = LIMIT_32M - remaining_start;
102    remaining_start = LIMIT_32M;
103    remaining_size  = rval;
104  }
105
106  policy = (0 == BSP_sbrk_policy[0] ? (uintptr_t)(-1) : BSP_sbrk_policy[0]);
107  switch ( policy ) {
108      case (uintptr_t)(-1):
109        area->size      += rval;
110        remaining_start  = (uintptr_t) area->begin + area->size;
111        remaining_size   = 0;
112      break;
113
114      case 0:
115        remaining_size = 0;
116      break;
117
118      default:
119        if ( rval > policy )
120          rval = policy;
121      break;
122  }
123
124  return (ptrdiff_t) (rval <= PTRDIFF_MAX ? rval : rval / 2);
125}
126
127/*
128 * This is just so the sbrk test can force its magic. All normal applications
129 * should just use the default implementation in this file.
130 */
131void *sbrk(ptrdiff_t incr) __attribute__ (( weak, alias("bsp_sbrk") ));
132static void *bsp_sbrk(ptrdiff_t incr)
133{
134  void *rval=(void*)-1;
135
136  if ( remaining_start != INVALID_REMAINING_START && incr <= remaining_size) {
137    remaining_size-=incr;
138    rval = (void *) remaining_start;
139    remaining_start += incr;
140  } else {
141    errno = ENOMEM;
142  }
143  #ifdef DEBUG
144    printk("************* SBRK 0x%08x (ret 0x%08x) **********\n", incr, rval);
145  #endif
146  return rval;
147}
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