include/lttng/ust-elf.h

   1 #ifndef _LTTNG_UST_ELF_H
   2 #define _LTTNG_UST_ELF_H
   3 /*
   4  * Copyright (C) 2015  Antoine Busque <abusque@efficios.com>
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #include <stdlib.h>
  22 #include <stdint.h>
  23 #include <stdio.h>
  24 #include <byteswap.h>
  25 #include <elf.h>
  26 #include <lttng/ust-endian.h>
  27
  28 /*
  29  * Determine native endianness in order to convert when reading an ELF
  30  * file if there is a mismatch.
  31  */
  32 #if BYTE_ORDER == LITTLE_ENDIAN
  33 #define NATIVE_ELF_ENDIANNESS ELFDATA2LSB
  34 #else
  35 #define NATIVE_ELF_ENDIANNESS ELFDATA2MSB
  36 #endif
  37
  38 /*
  39  * The size in bytes of the debug link CRC as contained in an ELF
  40  * section.
  41  */
  42 #define ELF_CRC_SIZE            4
  43 /*
  44  * ELF notes are aligned on 4 bytes. ref: ELF specification version
  45  * 1.1 p. 2-5.
  46  */
  47 #define ELF_NOTE_ENTRY_ALIGN    4
  48 /*
  49  * Within an ELF note, the `desc` field is also aligned on 4
  50  * bytes. ref: ELF specification version 1.1 p. 2-5.
  51  */
  52 #define ELF_NOTE_DESC_ALIGN     4
  53
  54 #define bswap(x)                                \
  55         do {                                    \
  56                 switch (sizeof(x)) {            \
  57                 case 8:                         \
  58                         x = bswap_64(x);        \
  59                         break;                  \
  60                 case 4:                         \
  61                         x = bswap_32(x);        \
  62                         break;                  \
  63                 case 2:                         \
  64                         x = bswap_16(x);        \
  65                         break;                  \
  66                 case 1:                         \
  67                         break;                  \
  68                 default:                        \
  69                         abort();                \
  70                 }                               \
  71         } while (0)
  72
  73 #define bswap_phdr(phdr)                \
  74         do {                            \
  75                 bswap((phdr).p_type);   \
  76                 bswap((phdr).p_offset); \
  77                 bswap((phdr).p_filesz); \
  78                 bswap((phdr).p_memsz);  \
  79                 bswap((phdr).p_align);  \
  80         } while (0)
  81
  82 #define bswap_shdr(shdr)                    \
  83         do {                                \
  84                 bswap((shdr).sh_name);      \
  85                 bswap((shdr).sh_type);      \
  86                 bswap((shdr).sh_flags);     \
  87                 bswap((shdr).sh_addr);      \
  88                 bswap((shdr).sh_offset);    \
  89                 bswap((shdr).sh_size);      \
  90                 bswap((shdr).sh_link);      \
  91                 bswap((shdr).sh_info);      \
  92                 bswap((shdr).sh_addralign); \
  93                 bswap((shdr).sh_entsize);   \
  94         } while (0)
  95
  96 #define bswap_ehdr(ehdr)                                \
  97         do {                                            \
  98                 bswap((ehdr).e_type);                   \
  99                 bswap((ehdr).e_machine);                \
 100                 bswap((ehdr).e_version);                \
 101                 bswap((ehdr).e_entry);                  \
 102                 bswap((ehdr).e_phoff);                  \
 103                 bswap((ehdr).e_shoff);                  \
 104                 bswap((ehdr).e_flags);                  \
 105                 bswap((ehdr).e_ehsize);                 \
 106                 bswap((ehdr).e_phentsize);              \
 107                 bswap((ehdr).e_phnum);                  \
 108                 bswap((ehdr).e_shentsize);              \
 109                 bswap((ehdr).e_shnum);                  \
 110                 bswap((ehdr).e_shstrndx);               \
 111         } while (0)
 112
 113 #define copy_phdr(src_phdr, dst_phdr)                           \
 114         do {                                                    \
 115                 (dst_phdr).p_type = (src_phdr).p_type;          \
 116                 (dst_phdr).p_offset = (src_phdr).p_offset;      \
 117                 (dst_phdr).p_filesz = (src_phdr).p_filesz;      \
 118                 (dst_phdr).p_memsz = (src_phdr).p_memsz;        \
 119                 (dst_phdr).p_align = (src_phdr).p_align;        \
 120         } while (0)
 121
 122 #define copy_shdr(src_shdr, dst_shdr)                                   \
 123         do {                                                            \
 124                 (dst_shdr).sh_name = (src_shdr).sh_name;                \
 125                 (dst_shdr).sh_type = (src_shdr).sh_type;                \
 126                 (dst_shdr).sh_flags = (src_shdr).sh_flags;              \
 127                 (dst_shdr).sh_addr = (src_shdr).sh_addr;                \
 128                 (dst_shdr).sh_offset = (src_shdr).sh_offset;            \
 129                 (dst_shdr).sh_size = (src_shdr).sh_size;                \
 130                 (dst_shdr).sh_link = (src_shdr).sh_link;                \
 131                 (dst_shdr).sh_info = (src_shdr).sh_info;                \
 132                 (dst_shdr).sh_addralign = (src_shdr).sh_addralign;      \
 133                 (dst_shdr).sh_entsize = (src_shdr).sh_entsize;          \
 134         } while (0)
 135
 136 #define copy_ehdr(src_ehdr, dst_ehdr)                                   \
 137         do {                                                            \
 138                 (dst_ehdr).e_type = (src_ehdr).e_type;                  \
 139                 (dst_ehdr).e_machine = (src_ehdr).e_machine;            \
 140                 (dst_ehdr).e_version = (src_ehdr).e_version;            \
 141                 (dst_ehdr).e_entry = (src_ehdr).e_entry;                \
 142                 (dst_ehdr).e_phoff = (src_ehdr).e_phoff;                \
 143                 (dst_ehdr).e_shoff = (src_ehdr).e_shoff;                \
 144                 (dst_ehdr).e_flags = (src_ehdr).e_flags;                \
 145                 (dst_ehdr).e_ehsize = (src_ehdr).e_ehsize;              \
 146                 (dst_ehdr).e_phentsize = (src_ehdr).e_phentsize;        \
 147                 (dst_ehdr).e_phnum = (src_ehdr).e_phnum;                \
 148                 (dst_ehdr).e_shentsize = (src_ehdr).e_shentsize;        \
 149                 (dst_ehdr).e_shnum = (src_ehdr).e_shnum;                \
 150                 (dst_ehdr).e_shstrndx = (src_ehdr).e_shstrndx;          \
 151         } while (0)
 152
 153 struct lttng_ust_elf_ehdr {
 154         uint16_t e_type;
 155         uint16_t e_machine;
 156         uint32_t e_version;
 157         uint64_t e_entry;
 158         uint64_t e_phoff;
 159         uint64_t e_shoff;
 160         uint32_t e_flags;
 161         uint16_t e_ehsize;
 162         uint16_t e_phentsize;
 163         uint16_t e_phnum;
 164         uint16_t e_shentsize;
 165         uint16_t e_shnum;
 166         uint16_t e_shstrndx;
 167 };
 168
 169 struct lttng_ust_elf_phdr {
 170         uint32_t p_type;
 171         uint64_t p_offset;
 172         uint64_t p_filesz;
 173         uint64_t p_memsz;
 174         uint64_t p_align;
 175 };
 176
 177 struct lttng_ust_elf_shdr {
 178         uint32_t sh_name;
 179         uint32_t sh_type;
 180         uint64_t sh_flags;
 181         uint64_t sh_addr;
 182         uint64_t sh_offset;
 183         uint64_t sh_size;
 184         uint32_t sh_link;
 185         uint32_t sh_info;
 186         uint64_t sh_addralign;
 187         uint64_t sh_entsize;
 188 };
 189
 190 struct lttng_ust_elf_nhdr {
 191         uint32_t n_namesz;
 192         uint32_t n_descsz;
 193         uint32_t n_type;
 194 };
 195
 196 struct lttng_ust_elf {
 197         /* Offset in bytes to start of section names string table. */
 198         uint64_t section_names_offset;
 199         /* Size in bytes of section names string table. */
 200         uint64_t section_names_size;
 201         char *path;
 202         int fd;
 203         struct lttng_ust_elf_ehdr *ehdr;
 204         uint8_t bitness;
 205         uint8_t endianness;
 206 };
 207
 208 static inline
 209 int is_elf_32_bit(struct lttng_ust_elf *elf)
 210 {
 211         return elf->bitness == ELFCLASS32;
 212 }
 213
 214 static inline
 215 int is_elf_native_endian(struct lttng_ust_elf *elf)
 216 {
 217         return elf->endianness == NATIVE_ELF_ENDIANNESS;
 218 }
 219
 220 struct lttng_ust_elf *lttng_ust_elf_create(const char *path);
 221 void lttng_ust_elf_destroy(struct lttng_ust_elf *elf);
 222 int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz);
 223 int lttng_ust_elf_get_build_id(struct lttng_ust_elf *elf, uint8_t **build_id,
 224                         size_t *length, int *found);
 225 int lttng_ust_elf_get_debug_link(struct lttng_ust_elf *elf, char **filename,
 226                         uint32_t *crc, int *found);
 227
 228 #endif  /* _LTTNG_UST_ELF_H */