1 /*
2 * Copyright 2004-2006, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
3 * Copyright 2002/03, Thomas Kurschel. All rights reserved.
4 *
5 * Distributed under the terms of the MIT License.
6 */
7
8 /*
9 VM helper functions.
10
11 Important assumption: get_memory_map must combine adjacent
12 physical pages, so contignous memory always leads to a S/G
13 list of length one.
14 */
15
16 #include "KernelExport_ext.h"
17 #include "wrapper.h"
18
19 #include <string.h>
20
21 #include <algorithm>
22
23
24 /** get sg list of iovec
25 * TBD: this should be moved to somewhere in kernel
26 */
27
28 status_t
get_iovec_memory_map(iovec * vec,size_t vec_count,size_t vec_offset,size_t len,physical_entry * map,uint32 max_entries,uint32 * num_entries,size_t * mapped_len)29 get_iovec_memory_map(iovec *vec, size_t vec_count, size_t vec_offset, size_t len,
30 physical_entry *map, uint32 max_entries, uint32 *num_entries, size_t *mapped_len)
31 {
32 uint32 cur_idx;
33 size_t left_len;
34
35 SHOW_FLOW(3, "vec_count=%" B_PRIuSIZE ", vec_offset=%" B_PRIuSIZE ", len=%"
36 B_PRIuSIZE ", max_entries=%" B_PRIu32, vec_count, vec_offset, len,
37 max_entries);
38
39 // skip iovec blocks if needed
40 while (vec_count > 0 && vec_offset > vec->iov_len) {
41 vec_offset -= vec->iov_len;
42 --vec_count;
43 ++vec;
44 }
45
46 for (left_len = len, cur_idx = 0; left_len > 0 && vec_count > 0
47 && cur_idx < max_entries;) {
48 char *range_start;
49 size_t range_len;
50 status_t res;
51 uint32 cur_num_entries, cur_mapped_len;
52 uint32 tmp_idx;
53
54 SHOW_FLOW( 3, "left_len=%d, vec_count=%d, cur_idx=%" B_PRIu32,
55 (int)left_len, (int)vec_count, cur_idx );
56
57 // map one iovec
58 range_start = (char *)vec->iov_base + vec_offset;
59 range_len = std::min(vec->iov_len - vec_offset, left_len);
60
61 SHOW_FLOW( 3, "range_start=%" B_PRIxADDR ", range_len=%" B_PRIxSIZE,
62 (addr_t)range_start, range_len );
63
64 vec_offset = 0;
65
66 cur_num_entries = max_entries - cur_idx;
67 if ((res = get_memory_map_etc(B_CURRENT_TEAM, range_start, range_len,
68 &map[cur_idx], &cur_num_entries)) != B_OK) {
69 // according to docu, no error is ever reported - argh!
70 SHOW_ERROR(1, "invalid io_vec passed (%s)", strerror(res));
71 return res;
72 }
73
74 cur_mapped_len = 0;
75
76 for (tmp_idx = cur_idx; tmp_idx < cur_idx + cur_num_entries; ++tmp_idx)
77 cur_mapped_len += map[tmp_idx].size;
78
79 if (cur_mapped_len == 0) {
80 panic("get_memory_map() returned empty list; left_len=%d, idx=%"
81 B_PRIu32 "/%" B_PRIu32, (int)left_len, cur_idx, max_entries);
82 SHOW_ERROR(2, "get_memory_map() returned empty list; left_len=%d, "
83 "idx=%" B_PRIu32 "/%" B_PRIu32, (int)left_len, cur_idx,
84 max_entries);
85 return B_ERROR;
86 }
87
88 SHOW_FLOW( 3, "cur_num_entries=%" B_PRIu32 ", cur_mapped_len=%x",
89 cur_num_entries, (int)cur_mapped_len );
90
91 // try to combine with previous sg block
92 if (cur_num_entries > 0 && cur_idx > 0
93 && map[cur_idx].address
94 == map[cur_idx - 1].address + map[cur_idx - 1].size) {
95 SHOW_FLOW0( 3, "combine with previous chunk" );
96 map[cur_idx - 1].size += map[cur_idx].size;
97 memcpy(&map[cur_idx], &map[cur_idx + 1],
98 (cur_num_entries - 1) * sizeof(map[0]));
99 --cur_num_entries;
100 }
101
102 cur_idx += cur_num_entries;
103 left_len -= cur_mapped_len;
104
105 // advance iovec if current one is described completely
106 if (cur_mapped_len == range_len) {
107 ++vec;
108 --vec_count;
109 }
110 }
111
112 *num_entries = cur_idx;
113 *mapped_len = len - left_len;
114
115 SHOW_FLOW( 3, "num_entries=%" B_PRIu32 ", mapped_len=%" B_PRIxSIZE,
116 *num_entries, *mapped_len);
117
118 return B_OK;
119 }
120
121