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                 bswap((phdr).p_vaddr);  \
  81         } while (0)
  82
  83 #define bswap_shdr(shdr)                    \
  84         do {                                \
  85                 bswap((shdr).sh_name);      \
  86                 bswap((shdr).sh_type);      \
  87                 bswap((shdr).sh_flags);     \
  88                 bswap((shdr).sh_addr);      \
  89                 bswap((shdr).sh_offset);    \
  90                 bswap((shdr).sh_size);      \
  91                 bswap((shdr).sh_link);      \
  92                 bswap((shdr).sh_info);      \
  93                 bswap((shdr).sh_addralign); \
  94                 bswap((shdr).sh_entsize);   \
  95         } while (0)
  96
  97 #define bswap_ehdr(ehdr)                                \
  98         do {                                            \
  99                 bswap((ehdr).e_type);                   \
 100                 bswap((ehdr).e_machine);                \
 101                 bswap((ehdr).e_version);                \
 102                 bswap((ehdr).e_entry);                  \
 103                 bswap((ehdr).e_phoff);                  \
 104                 bswap((ehdr).e_shoff);                  \
 105                 bswap((ehdr).e_flags);                  \
 106                 bswap((ehdr).e_ehsize);                 \
 107                 bswap((ehdr).e_phentsize);              \
 108                 bswap((ehdr).e_phnum);                  \
 109                 bswap((ehdr).e_shentsize);              \
 110                 bswap((ehdr).e_shnum);                  \
 111                 bswap((ehdr).e_shstrndx);               \
 112         } while (0)
 113
 114 #define copy_phdr(src_phdr, dst_phdr)                           \
 115         do {                                                    \
 116                 (dst_phdr).p_type = (src_phdr).p_type;          \
 117                 (dst_phdr).p_offset = (src_phdr).p_offset;      \
 118                 (dst_phdr).p_filesz = (src_phdr).p_filesz;      \
 119                 (dst_phdr).p_memsz = (src_phdr).p_memsz;        \
 120                 (dst_phdr).p_align = (src_phdr).p_align;        \
 121                 (dst_phdr).p_vaddr = (src_phdr).p_vaddr;        \
 122         } while (0)
 123
 124 #define copy_shdr(src_shdr, dst_shdr)                                   \
 125         do {                                                            \
 126                 (dst_shdr).sh_name = (src_shdr).sh_name;                \
 127                 (dst_shdr).sh_type = (src_shdr).sh_type;                \
 128                 (dst_shdr).sh_flags = (src_shdr).sh_flags;              \
 129                 (dst_shdr).sh_addr = (src_shdr).sh_addr;                \
 130                 (dst_shdr).sh_offset = (src_shdr).sh_offset;            \
 131                 (dst_shdr).sh_size = (src_shdr).sh_size;                \
 132                 (dst_shdr).sh_link = (src_shdr).sh_link;                \
 133                 (dst_shdr).sh_info = (src_shdr).sh_info;                \
 134                 (dst_shdr).sh_addralign = (src_shdr).sh_addralign;      \
 135                 (dst_shdr).sh_entsize = (src_shdr).sh_entsize;          \
 136         } while (0)
 137
 138 #define copy_ehdr(src_ehdr, dst_ehdr)                                   \
 139         do {                                                            \
 140                 (dst_ehdr).e_type = (src_ehdr).e_type;                  \
 141                 (dst_ehdr).e_machine = (src_ehdr).e_machine;            \
 142                 (dst_ehdr).e_version = (src_ehdr).e_version;            \
 143                 (dst_ehdr).e_entry = (src_ehdr).e_entry;                \
 144                 (dst_ehdr).e_phoff = (src_ehdr).e_phoff;                \
 145                 (dst_ehdr).e_shoff = (src_ehdr).e_shoff;                \
 146                 (dst_ehdr).e_flags = (src_ehdr).e_flags;                \
 147                 (dst_ehdr).e_ehsize = (src_ehdr).e_ehsize;              \
 148                 (dst_ehdr).e_phentsize = (src_ehdr).e_phentsize;        \
 149                 (dst_ehdr).e_phnum = (src_ehdr).e_phnum;                \
 150                 (dst_ehdr).e_shentsize = (src_ehdr).e_shentsize;        \
 151                 (dst_ehdr).e_shnum = (src_ehdr).e_shnum;                \
 152                 (dst_ehdr).e_shstrndx = (src_ehdr).e_shstrndx;          \
 153         } while (0)
 154
 155 struct lttng_ust_elf_ehdr {
 156         uint16_t e_type;
 157         uint16_t e_machine;
 158         uint32_t e_version;
 159         uint64_t e_entry;
 160         uint64_t e_phoff;
 161         uint64_t e_shoff;
 162         uint32_t e_flags;
 163         uint16_t e_ehsize;
 164         uint16_t e_phentsize;
 165         uint16_t e_phnum;
 166         uint16_t e_shentsize;
 167         uint16_t e_shnum;
 168         uint16_t e_shstrndx;
 169 };
 170
 171 struct lttng_ust_elf_phdr {
 172         uint32_t p_type;
 173         uint64_t p_offset;
 174         uint64_t p_filesz;
 175         uint64_t p_memsz;
 176         uint64_t p_align;
 177         uint64_t p_vaddr;
 178 };
 179
 180 struct lttng_ust_elf_shdr {
 181         uint32_t sh_name;
 182         uint32_t sh_type;
 183         uint64_t sh_flags;
 184         uint64_t sh_addr;
 185         uint64_t sh_offset;
 186         uint64_t sh_size;
 187         uint32_t sh_link;
 188         uint32_t sh_info;
 189         uint64_t sh_addralign;
 190         uint64_t sh_entsize;
 191 };
 192
 193 struct lttng_ust_elf_nhdr {
 194         uint32_t n_namesz;
 195         uint32_t n_descsz;
 196         uint32_t n_type;
 197 };
 198
 199 struct lttng_ust_elf {
 200         /* Offset in bytes to start of section names string table. */
 201         off_t section_names_offset;
 202         /* Size in bytes of section names string table. */
 203         size_t section_names_size;
 204         char *path;
 205         int fd;
 206         struct lttng_ust_elf_ehdr *ehdr;
 207         uint8_t bitness;
 208         uint8_t endianness;
 209 };
 210
 211 static inline
 212 int is_elf_32_bit(struct lttng_ust_elf *elf)
 213 {
 214         return elf->bitness == ELFCLASS32;
 215 }
 216
 217 static inline
 218 int is_elf_native_endian(struct lttng_ust_elf *elf)
 219 {
 220         return elf->endianness == NATIVE_ELF_ENDIANNESS;
 221 }
 222
 223 struct lttng_ust_elf *lttng_ust_elf_create(const char *path);
 224 void lttng_ust_elf_destroy(struct lttng_ust_elf *elf);
 225 uint8_t lttng_ust_elf_is_pic(struct lttng_ust_elf *elf);
 226 int lttng_ust_elf_get_memsz(struct lttng_ust_elf *elf, uint64_t *memsz);
 227 int lttng_ust_elf_get_build_id(struct lttng_ust_elf *elf, uint8_t **build_id,
 228                         size_t *length, int *found);
 229 int lttng_ust_elf_get_debug_link(struct lttng_ust_elf *elf, char **filename,
 230                         uint32_t *crc, int *found);
 231
 232 #endif  /* _LTTNG_UST_ELF_H */