1 /*- 2 * Copyright (c) 2013 David Chisnall 3 * All rights reserved. 4 * 5 * This software was developed by SRI International and the University of 6 * Cambridge Computer Laboratory under DARPA/AFRL contract (FA8750-10-C-0237) 7 * ("CTSRD"), as part of the DARPA CRASH research programme. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 28 * SUCH DAMAGE. 29 * 30 * $FreeBSD$ 31 */ 32 33 #ifndef _DTB_HH_ 34 #define _DTB_HH_ 35 #include <map> 36 #include <string> 37 38 #include <assert.h> 39 40 #include "input_buffer.hh" 41 #include "util.hh" 42 43 namespace dtc 44 { 45 /** 46 * The dtb namespace contains code related to the generation of device tree 47 * blobs, the binary representation of flattened device trees. The abstract 48 * tree representation calls into this code to generate the output. 49 */ 50 namespace dtb 51 { 52 /** The token types in the DTB, as defined by §7.4.1 of the ePAPR 53 * specification. All of these values are written in big-endian format in the 54 * output. 55 */ 56 enum token_type 57 { 58 /** 59 * Marker indicating the start of a node in the tree. This is followed 60 * by the nul-terminated name. If a unit address is specified, then 61 * the name also contains the address, with an @ symbol between the end 62 * of the name and the start of the address. 63 * 64 * The name is then padded such that the next token begins on a 4-byte 65 * boundary. The node may contain properties, other nodes, both, or be 66 * empty. 67 */ 68 FDT_BEGIN_NODE = 0x00000001, 69 /** 70 * Marker indicating the end of a node. 71 */ 72 FDT_END_NODE = 0x00000002, 73 /** 74 * The start of a property. This is followed by two 32-bit big-endian 75 * values. The first indicates the length of the property value, the 76 * second its index in the strings table. It is then followed by the 77 * property value, if the value is of non-zero length. 78 */ 79 FDT_PROP = 0x00000003, 80 /** 81 * Ignored token. May be used for padding inside DTB nodes. 82 */ 83 FDT_NOP = 0x00000004, 84 /** 85 * Marker indicating the end of the tree. 86 */ 87 FDT_END = 0x00000009 88 }; 89 90 /** 91 * Returns the token as a string. This is used for debugging and for printing 92 * human-friendly error messages about malformed DTB input. 93 */ 94 inline const char *token_type_name(token_type t) 95 { 96 switch(t) 97 { 98 case FDT_BEGIN_NODE: 99 return "FDT_BEGIN_NODE"; 100 case FDT_END_NODE: 101 return "FDT_END_NODE"; 102 case FDT_PROP: 103 return "FDT_PROP"; 104 case FDT_NOP: 105 return "FDT_NOP"; 106 case FDT_END: 107 return "FDT_END"; 108 } 109 assert(0); 110 } 111 112 /** 113 * Abstract class for writing a section of the output. We create one 114 * of these for each section that needs to be written. It is intended to build 115 * a temporary buffer of the output in memory and then write it to a file 116 * stream. The size can be returned after all of the data has been written 117 * into the internal buffer, so the sizes of the three tables can be calculated 118 * before storing them in the buffer. 119 */ 120 struct output_writer 121 { 122 /** 123 * Writes a label into the output stream. This is only applicable for 124 * assembly output, where the labels become symbols that can be 125 * resolved at link time. 126 */ 127 virtual void write_label(const std::string &name) = 0; 128 /** 129 * Writes a comment into the output stream. Useful only when debugging 130 * the output. 131 */ 132 virtual void write_comment(const std::string &name) = 0; 133 /** 134 * Writes a string. A nul terminator is implicitly added. 135 */ 136 virtual void write_string(const std::string &name) = 0; 137 /** 138 * Writes a single 8-bit value. 139 */ 140 virtual void write_data(uint8_t) = 0; 141 /** 142 * Writes a single 32-bit value. The value is written in big-endian 143 * format, but should be passed in the host's native endian. 144 */ 145 virtual void write_data(uint32_t) = 0; 146 /** 147 * Writes a single 64-bit value. The value is written in big-endian 148 * format, but should be passed in the host's native endian. 149 */ 150 virtual void write_data(uint64_t) = 0; 151 /** 152 * Writes the collected output to the specified file descriptor. 153 */ 154 virtual void write_to_file(int fd) = 0; 155 /** 156 * Returns the number of bytes. 157 */ 158 virtual uint32_t size() = 0; 159 /** 160 * Helper for writing tokens to the output stream. This writes a 161 * comment above the token describing its value, for easier debugging 162 * of the output. 163 */ 164 inline void write_token(token_type t) 165 { 166 write_comment(token_type_name(t)); 167 write_data((uint32_t)t); 168 } 169 /** 170 * Helper function that writes a byte buffer to the output, one byte at 171 * a time. 172 */ 173 void write_data(byte_buffer b); 174 }; 175 176 /** 177 * Binary file writer. This class is responsible for writing the DTB output 178 * directly in blob format. 179 */ 180 class binary_writer : public output_writer 181 { 182 /** 183 * The internal buffer used to store the blob while it is being 184 * constructed. 185 */ 186 byte_buffer buffer; 187 public: 188 /** 189 * The binary format does not support labels, so this method 190 * does nothing. 191 */ 192 void write_label(const std::string &) override {} 193 /** 194 * Comments are ignored by the binary writer. 195 */ 196 void write_comment(const std::string&) override {} 197 void write_string(const std::string &name) override; 198 void write_data(uint8_t v) override; 199 void write_data(uint32_t v) override; 200 void write_data(uint64_t v) override; 201 void write_to_file(int fd) override; 202 uint32_t size() override; 203 }; 204 /** 205 * Assembly writer. This class is responsible for writing the output in an 206 * assembly format that is suitable for linking into a kernel, loader, and so 207 * on. 208 */ 209 class asm_writer : public output_writer 210 { 211 /** 212 * The internal buffer for temporary values. Note that this actually 213 * contains ASCII text, but it is a byte buffer so that we can just 214 * copy strings across as-is. 215 */ 216 byte_buffer buffer; 217 /** 218 * The number of bytes written to the current line. This is used to 219 * allow line wrapping, where we aim to write four .byte directives to 220 * make the alignment clearer. 221 */ 222 int byte_count; 223 /** 224 * The current number of bytes written. This is the number in binary 225 * format, not the number of bytes in the buffer. 226 */ 227 uint32_t bytes_written; 228 229 /** 230 * Writes a string directly to the output as-is. This is the function that 231 * performs the real output. 232 */ 233 void write_string(const char *c); 234 /** 235 * Write a string to the output. 236 */ 237 void write_string(const std::string &c) override; 238 /** 239 * Writes the string, starting on a new line. 240 */ 241 void write_line(const char *c); 242 /** 243 * Writes a byte in binary format. This will emit a single .byte 244 * directive, with up to four per line. 245 */ 246 void write_byte(uint8_t b); 247 public: 248 asm_writer() : byte_count(0), bytes_written(0) {} 249 void write_label(const std::string &name) override; 250 void write_comment(const std::string &name) override; 251 void write_data(uint8_t v) override; 252 void write_data(uint32_t v) override; 253 void write_data(uint64_t v) override; 254 void write_to_file(int fd) override; 255 uint32_t size() override; 256 }; 257 258 /** 259 * Class encapsulating the device tree blob header. This class stores all of 260 * the values found in the header and is responsible for writing them to the 261 * output. 262 */ 263 struct header 264 { 265 /** 266 * Magic value, used to validate that this really is a device tree 267 * blob. Should always be set to 0xd00dfeed. 268 */ 269 uint32_t magic; 270 /** 271 * The total size of the blob, including header, reservations, strings 272 * table, and padding. 273 */ 274 uint32_t totalsize; 275 /** 276 * The offset from the start of the blob of the struct table (i.e. the 277 * part of the blob containing the entire device tree). 278 */ 279 uint32_t off_dt_struct; 280 /** 281 * The offset from the start of the blob of the strings table. 282 */ 283 uint32_t off_dt_strings; 284 /** 285 * The offset of the reservation map from the start of the blob. 286 */ 287 uint32_t off_mem_rsvmap; 288 /** 289 * The version of the blob. This should always be 17. 290 */ 291 uint32_t version; 292 /** 293 * The earliest version of the DTB specification with which this blob 294 * is backwards compatible. This should always be 16. 295 */ 296 uint32_t last_comp_version; 297 /** 298 * The ID of the CPU where this boots. 299 */ 300 uint32_t boot_cpuid_phys; 301 /** 302 * The size of the strings table. 303 */ 304 uint32_t size_dt_strings; 305 /** 306 * The size of the struct table. 307 */ 308 uint32_t size_dt_struct; 309 /** 310 * Writes the entire header to the specified output buffer. 311 */ 312 void write(output_writer &out); 313 /** 314 * Reads the header from bits binary representation in a blob. 315 */ 316 bool read_dtb(input_buffer &input); 317 /** 318 * Default constructor. Initialises the values that have sensible 319 * defaults, leaves the others blank. 320 */ 321 header() : magic(0xd00dfeed), version(17), last_comp_version(16), 322 boot_cpuid_phys(0) {} 323 }; 324 325 /** 326 * Class encapsulating the string table. FDT strings are stored in a string 327 * section. This maintains a map from strings to their offsets in the strings 328 * section. 329 * 330 * Note: We don't currently do suffix matching, which may save a small amount 331 * of space. 332 */ 333 class string_table { 334 /** 335 * Map from strings to their offset. 336 */ 337 std::map<std::string, uint32_t> string_offsets; 338 /** 339 * The strings, in the order in which they should be written to the 340 * output. The order must be stable - adding another string must not 341 * change the offset of any that we have already referenced - and so we 342 * simply write the strings in the order that they are passed. 343 */ 344 std::vector<std::string> strings; 345 /** 346 * The current size of the strings section. 347 */ 348 uint32_t size; 349 public: 350 /** 351 * Default constructor, creates an empty strings table. 352 */ 353 string_table() : size(0) {} 354 /** 355 * Adds a string to the table, returning the offset from the start 356 * where it will be written. If the string is already present, this 357 * will return its existing offset, otherwise it will return a new 358 * offset. 359 */ 360 uint32_t add_string(const std::string &str); 361 /** 362 * Writes the strings table to the specified output. 363 */ 364 void write(dtb::output_writer &writer); 365 }; 366 367 } // namespace dtb 368 369 } // namespace dtc 370 371 #endif // !_DTB_HH_ 372