| 1 | /* subr_rmap.c 4.4 81/03/09 */ |
| 2 | |
| 3 | #include "../h/param.h" |
| 4 | #include "../h/systm.h" |
| 5 | #include "../h/map.h" |
| 6 | #include "../h/dir.h" |
| 7 | #include "../h/user.h" |
| 8 | #include "../h/proc.h" |
| 9 | #include "../h/mtpr.h" |
| 10 | #include "../h/text.h" |
| 11 | |
| 12 | /* |
| 13 | * Resource map handling routines. |
| 14 | * |
| 15 | * A resource map is an array of structures each |
| 16 | * of which describes a segment of the address space of an available |
| 17 | * resource. The segments are described by their base address and |
| 18 | * length, and sorted in address order. Each resource map has a fixed |
| 19 | * maximum number of segments allowed. Resources are allocated |
| 20 | * by taking part or all of one of the segments of the map. |
| 21 | * |
| 22 | * Returning of resources will require another segment if |
| 23 | * the returned resources are not adjacent in the address |
| 24 | * space to an existing segment. If the return of a segment |
| 25 | * would require a slot which is not available, then one of |
| 26 | * the resource map segments is discarded after a warning is printed. |
| 27 | * Returning of resources may also cause the map to collapse |
| 28 | * by coalescing two existing segments and the returned space |
| 29 | * into a single segment. In this case the resource map is |
| 30 | * made smaller by copying together to fill the resultant gap. |
| 31 | * |
| 32 | * N.B.: the current implementation uses a dense array and does |
| 33 | * not admit the value ``0'' as a legal address, since that is used |
| 34 | * as a delimiter. |
| 35 | */ |
| 36 | |
| 37 | /* |
| 38 | * Initialize map mp to have (mapsize-2) segments |
| 39 | * and to be called ``name'', which we print if |
| 40 | * the slots become so fragmented that we lose space. |
| 41 | * The map itself is initialized with size elements free |
| 42 | * starting at addr. |
| 43 | */ |
| 44 | rminit(mp, size, addr, name, mapsize) |
| 45 | register struct map *mp; |
| 46 | int size, addr; |
| 47 | char *name; |
| 48 | int mapsize; |
| 49 | { |
| 50 | register struct mapent *ep = (struct mapent *)(mp+1); |
| 51 | |
| 52 | mp->m_name = name; |
| 53 | /* N.B.: WE ASSUME HERE THAT sizeof (struct map) == sizeof (struct mapent) */ |
| 54 | /* |
| 55 | * One of the mapsize slots is taken by the map structure, |
| 56 | * segments has size 0 and addr 0, and acts as a delimiter. |
| 57 | * We insure that we never use segments past the end of |
| 58 | * the array which is given by mp->m_limit. |
| 59 | * Instead, when excess segments occur we discard some resources. |
| 60 | */ |
| 61 | mp->m_limit = (struct mapent *)&mp[mapsize]; |
| 62 | /* |
| 63 | * Simulate a rmfree(), but with the option to |
| 64 | * call with size 0 and addr 0 when we just want |
| 65 | * to initialize without freeing. |
| 66 | */ |
| 67 | ep->m_size = size; |
| 68 | ep->m_addr = addr; |
| 69 | } |
| 70 | |
| 71 | /* |
| 72 | * Allocate 'size' units from the given |
| 73 | * map. Return the base of the allocated space. |
| 74 | * In a map, the addresses are increasing and the |
| 75 | * list is terminated by a 0 size. |
| 76 | * |
| 77 | * Algorithm is first-fit. |
| 78 | * |
| 79 | * This routine knows about the interleaving of the swapmap |
| 80 | * and handles that. |
| 81 | */ |
| 82 | rmalloc(mp, size) |
| 83 | register struct map *mp; |
| 84 | { |
| 85 | register struct mapent *ep = (struct mapent *)(mp+1); |
| 86 | register int addr; |
| 87 | register struct mapent *bp; |
| 88 | swblk_t first, rest; |
| 89 | |
| 90 | if (size <= 0 || mp == swapmap && size > DMMAX) |
| 91 | panic("rmalloc"); |
| 92 | /* |
| 93 | * Search for a piece of the resource map which has enough |
| 94 | * free space to accomodate the request. |
| 95 | */ |
| 96 | for (bp = ep; bp->m_size; bp++) { |
| 97 | if (bp->m_size >= size) { |
| 98 | /* |
| 99 | * If allocating from swapmap, |
| 100 | * then have to respect interleaving |
| 101 | * boundaries. |
| 102 | */ |
| 103 | if (mp == swapmap && |
| 104 | (first = DMMAX - bp->m_addr%DMMAX) < bp->m_size) { |
| 105 | if (bp->m_size - first < size) |
| 106 | continue; |
| 107 | addr = bp->m_addr + first; |
| 108 | rest = bp->m_size - first - size; |
| 109 | bp->m_size = first; |
| 110 | if (rest) |
| 111 | rmfree(swapmap, rest, addr+size); |
| 112 | return (addr); |
| 113 | } |
| 114 | /* |
| 115 | * Allocate from the map. |
| 116 | * If there is no space left of the piece |
| 117 | * we allocated from, move the rest of |
| 118 | * the pieces to the left. |
| 119 | */ |
| 120 | addr = bp->m_addr; |
| 121 | bp->m_addr += size; |
| 122 | if ((bp->m_size -= size) == 0) { |
| 123 | do { |
| 124 | bp++; |
| 125 | (bp-1)->m_addr = bp->m_addr; |
| 126 | } while ((bp-1)->m_size = bp->m_size); |
| 127 | } |
| 128 | if (mp == swapmap && addr % CLSIZE) |
| 129 | panic("rmalloc swapmap"); |
| 130 | return (addr); |
| 131 | } |
| 132 | } |
| 133 | return (0); |
| 134 | } |
| 135 | |
| 136 | /* |
| 137 | * Free the previously allocated space at addr |
| 138 | * of size units into the specified map. |
| 139 | * Sort addr into map and combine on |
| 140 | * one or both ends if possible. |
| 141 | */ |
| 142 | rmfree(mp, size, addr) |
| 143 | struct map *mp; |
| 144 | register int size, addr; |
| 145 | { |
| 146 | struct mapent *firstbp; |
| 147 | register struct mapent *bp; |
| 148 | register int t; |
| 149 | |
| 150 | /* |
| 151 | * Both address and size must be |
| 152 | * positive, or the protocol has broken down. |
| 153 | */ |
| 154 | if (addr <= 0 || size <= 0) |
| 155 | goto badrmfree; |
| 156 | /* |
| 157 | * Locate the piece of the map which starts after the |
| 158 | * returned space (or the end of the map). |
| 159 | */ |
| 160 | firstbp = bp = (struct mapent *)(mp + 1); |
| 161 | for (; bp->m_addr <= addr && bp->m_size != 0; bp++) |
| 162 | continue; |
| 163 | /* |
| 164 | * If the piece on the left abuts us, |
| 165 | * then we should combine with it. |
| 166 | */ |
| 167 | if (bp > firstbp && (bp-1)->m_addr+(bp-1)->m_size >= addr) { |
| 168 | /* |
| 169 | * Check no overlap (internal error). |
| 170 | */ |
| 171 | if ((bp-1)->m_addr+(bp-1)->m_size > addr) |
| 172 | goto badrmfree; |
| 173 | /* |
| 174 | * Add into piece on the left by increasing its size. |
| 175 | */ |
| 176 | (bp-1)->m_size += size; |
| 177 | /* |
| 178 | * If the combined piece abuts the piece on |
| 179 | * the right now, compress it in also, |
| 180 | * by shifting the remaining pieces of the map over. |
| 181 | */ |
| 182 | if (bp->m_addr && addr+size >= bp->m_addr) { |
| 183 | if (addr+size > bp->m_addr) |
| 184 | goto badrmfree; |
| 185 | (bp-1)->m_size += bp->m_size; |
| 186 | while (bp->m_size) { |
| 187 | bp++; |
| 188 | (bp-1)->m_addr = bp->m_addr; |
| 189 | (bp-1)->m_size = bp->m_size; |
| 190 | } |
| 191 | } |
| 192 | goto done; |
| 193 | } |
| 194 | /* |
| 195 | * Don't abut on the left, check for abutting on |
| 196 | * the right. |
| 197 | */ |
| 198 | if (addr+size >= bp->m_addr && bp->m_size) { |
| 199 | if (addr+size > bp->m_addr) |
| 200 | goto badrmfree; |
| 201 | bp->m_addr -= size; |
| 202 | bp->m_size += size; |
| 203 | goto done; |
| 204 | } |
| 205 | /* |
| 206 | * Don't abut at all. Make a new entry |
| 207 | * and check for map overflow. |
| 208 | */ |
| 209 | do { |
| 210 | t = bp->m_addr; |
| 211 | bp->m_addr = addr; |
| 212 | addr = t; |
| 213 | t = bp->m_size; |
| 214 | bp->m_size = size; |
| 215 | bp++; |
| 216 | } while (size = t); |
| 217 | /* |
| 218 | * Segment at bp is to be the delimiter; |
| 219 | * If there is not room for it |
| 220 | * then the table is too full |
| 221 | * and we must discard something. |
| 222 | */ |
| 223 | if (bp+1 > mp->m_limit) { |
| 224 | /* |
| 225 | * Back bp up to last available segment. |
| 226 | * which contains a segment already and must |
| 227 | * be made into the delimiter. |
| 228 | * Discard second to last entry, |
| 229 | * since it is presumably smaller than the last |
| 230 | * and move the last entry back one. |
| 231 | */ |
| 232 | bp--; |
| 233 | printf("%s: rmap ovflo, lost [%d,%d)\n", mp->m_name, |
| 234 | (bp-1)->m_addr, (bp-1)->m_addr+(bp-1)->m_size); |
| 235 | bp[-1] = bp[0]; |
| 236 | bp[0].m_size = bp[0].m_addr = 0; |
| 237 | } |
| 238 | done: |
| 239 | /* |
| 240 | * THIS IS RIDICULOUS... IT DOESN'T BELONG HERE! |
| 241 | */ |
| 242 | if ((mp == kernelmap) && kmapwnt) { |
| 243 | kmapwnt = 0; |
| 244 | wakeup((caddr_t)kernelmap); |
| 245 | } |
| 246 | return; |
| 247 | badrmfree: |
| 248 | panic("bad rmfree"); |
| 249 | } |