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 29 get_iovec_memory_map(iovec *vec, size_t vec_count, size_t vec_offset, size_t len, 30 physical_entry *map, size_t max_entries, size_t *num_entries, size_t *mapped_len) 31 { 32 size_t cur_idx; 33 size_t left_len; 34 35 SHOW_FLOW(3, "vec_count=%lu, vec_offset=%lu, len=%lu, max_entries=%lu", 36 vec_count, vec_offset, len, max_entries); 37 38 // skip iovec blocks if needed 39 while (vec_count > 0 && vec_offset > vec->iov_len) { 40 vec_offset -= vec->iov_len; 41 --vec_count; 42 ++vec; 43 } 44 45 for (left_len = len, cur_idx = 0; left_len > 0 && vec_count > 0 && cur_idx < max_entries;) { 46 char *range_start; 47 size_t range_len; 48 status_t res; 49 size_t cur_num_entries, cur_mapped_len; 50 uint32 tmp_idx; 51 52 SHOW_FLOW( 3, "left_len=%d, vec_count=%d, cur_idx=%d", 53 (int)left_len, (int)vec_count, (int)cur_idx ); 54 55 // map one iovec 56 range_start = (char *)vec->iov_base + vec_offset; 57 range_len = std::min(vec->iov_len - vec_offset, left_len); 58 59 SHOW_FLOW( 3, "range_start=%x, range_len=%x", 60 (int)range_start, (int)range_len ); 61 62 vec_offset = 0; 63 64 if ((res = get_memory_map(range_start, range_len, &map[cur_idx], 65 max_entries - cur_idx)) != B_OK) { 66 // according to docu, no error is ever reported - argh! 67 SHOW_ERROR(1, "invalid io_vec passed (%s)", strerror(res)); 68 return res; 69 } 70 71 // stupid: get_memory_map does neither tell how many sg blocks 72 // are used nor whether there were enough sg blocks at all; 73 // -> determine that manually 74 // TODO: Use get_memory_map_etc()! 75 cur_mapped_len = 0; 76 cur_num_entries = 0; 77 78 for (tmp_idx = cur_idx; tmp_idx < max_entries; ++tmp_idx) { 79 if (map[tmp_idx].size == 0) 80 break; 81 82 cur_mapped_len += map[tmp_idx].size; 83 ++cur_num_entries; 84 } 85 86 if (cur_mapped_len == 0) { 87 panic("get_memory_map() returned empty list; left_len=%d, idx=%d/%d", 88 (int)left_len, (int)cur_idx, (int)max_entries); 89 SHOW_ERROR(2, "get_memory_map() returned empty list; left_len=%d, idx=%d/%d", 90 (int)left_len, (int)cur_idx, (int)max_entries); 91 return B_ERROR; 92 } 93 94 SHOW_FLOW( 3, "cur_num_entries=%d, cur_mapped_len=%x", 95 (int)cur_num_entries, (int)cur_mapped_len ); 96 97 // try to combine with previous sg block 98 if (cur_num_entries > 0 && cur_idx > 0 99 && map[cur_idx].address 100 == map[cur_idx - 1].address + map[cur_idx - 1].size) { 101 SHOW_FLOW0( 3, "combine with previous chunk" ); 102 map[cur_idx - 1].size += map[cur_idx].size; 103 memcpy(&map[cur_idx], &map[cur_idx + 1], (cur_num_entries - 1) * sizeof(map[0])); 104 --cur_num_entries; 105 } 106 107 cur_idx += cur_num_entries; 108 left_len -= cur_mapped_len; 109 110 // advance iovec if current one is described completely 111 if (cur_mapped_len == range_len) { 112 ++vec; 113 --vec_count; 114 } 115 } 116 117 *num_entries = cur_idx; 118 *mapped_len = len - left_len; 119 120 SHOW_FLOW( 3, "num_entries=%d, mapped_len=%x", 121 (int)*num_entries, (int)*mapped_len ); 122 123 return B_OK; 124 } 125 126