sys/sys/link_elf.h

   1 /*
   2  * Copyright (c) 1993 Paul Kranenburg
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by Paul Kranenburg.
  16  * 4. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  22  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  23  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  24  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  28  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  * $FreeBSD: src/sys/sys/link_elf.h,v 1.20.2.2 2003/02/20 20:42:46 kan Exp $
  31  * $DragonFly: src/sys/sys/link_elf.h,v 1.3 2003/08/20 07:31:21 rob Exp $
  32  */
  33
  34 /*
  35  * RRS section definitions.
  36  *
  37  * The layout of some data structures defined in this header file is
  38  * such that we can provide compatibility with the SunOS 4.x shared
  39  * library scheme.
  40  */
  41
  42 #ifndef _LINK_H_
  43 #define _LINK_H_
  44
  45 #if (defined(FREEBSD_ELF) || defined(__ELF__)) && !defined(FREEBSD_AOUT)
  46
  47 #include <sys/types.h>
  48
  49 /*
  50  * Flags that describe the origin of the entries in Dl_serinfo.
  51  * SunOS has these in <sys/link.h>, we follow the suit.
  52  */
  53 #define LA_SER_ORIG     0x01    /* original (needed) name */
  54 #define LA_SER_LIBPATH  0x02    /* LD_LIBRARY_PATH entry prepended */
  55 #define LA_SER_RUNPATH  0x04    /* runpath entry prepended */
  56 #define LA_SER_CONFIG   0x08    /* configuration entry prepended */
  57 #define LA_SER_DEFAULT  0x40    /* default path prepended */
  58 #define LA_SER_SECURE   0x80    /* default (secure) path prepended */
  59
  60 typedef struct link_map {
  61         caddr_t         l_addr;                 /* Base Address of library */
  62 #ifdef __mips__
  63         caddr_t         l_offs;                 /* Load Offset of library */
  64 #endif
  65         const char      *l_name;                /* Absolute Path to Library */
  66         const void      *l_ld;                  /* Pointer to .dynamic in memory */
  67         struct link_map *l_next, *l_prev;       /* linked list of of mapped libs */
  68 } Link_map;
  69
  70 struct r_debug {
  71         int             r_version;              /* not used */
  72         struct link_map *r_map;                 /* list of loaded images */
  73         void            (*r_brk)(struct r_debug *, struct link_map *);
  74                                                 /* pointer to break point */
  75         enum {
  76             RT_CONSISTENT,                      /* things are stable */
  77             RT_ADD,                             /* adding a shared library */
  78             RT_DELETE                           /* removing a shared library */
  79         }               r_state;
  80 };
  81
  82 #else /* !__ELF__ */
  83
  84 struct dl_info;
  85
  86 /*
  87  * A `Shared Object Descriptor' describes a shared object that is needed
  88  * to complete the link edit process of the object containing it.
  89  * A list of such objects (chained through `sod_next') is pointed at
  90  * by `sdt_sods' in the section_dispatch_table structure.
  91  */
  92
  93 struct sod {    /* Shared Object Descriptor */
  94         long    sod_name;               /* name (relative to load address) */
  95         u_int   sod_library  : 1,       /* Searched for by library rules */
  96                 sod_reserved : 31;
  97         short   sod_major;              /* major version number */
  98         short   sod_minor;              /* minor version number */
  99         long    sod_next;               /* next sod */
 100 };
 101
 102 /*
 103  * `Shared Object Map's are used by the run-time link editor (ld.so) to
 104  * keep track of all shared objects loaded into a process' address space.
 105  * These structures are only used at run-time and do not occur within
 106  * the text or data segment of an executable or shared library.
 107  */
 108 struct so_map {         /* Shared Object Map */
 109         caddr_t         som_addr;       /* Address at which object mapped */
 110         char            *som_path;      /* Path to mmap'ed file */
 111         struct so_map   *som_next;      /* Next map in chain */
 112         struct sod      *som_sod;       /* Sod responsible for this map */
 113         caddr_t         som_sodbase;    /* Base address of this sod */
 114         u_int           som_write : 1;  /* Text is currently writable */
 115         struct _dynamic *som_dynamic;   /* _dynamic structure */
 116         caddr_t         som_spd;        /* Private data */
 117 };
 118
 119 /*
 120  * Symbol description with size. This is simply an `nlist' with
 121  * one field (nz_size) added.
 122  * Used to convey size information on items in the data segment
 123  * of shared objects. An array of these live in the shared object's
 124  * text segment and is addressed by the `sdt_nzlist' field.
 125  */
 126 struct nzlist {
 127         struct nlist    nlist;
 128         u_long          nz_size;
 129 };
 130
 131 #define nz_un           nlist.n_un
 132 #define nz_strx         nlist.n_un.n_strx
 133 #define nz_name         nlist.n_un.n_name
 134 #define nz_type         nlist.n_type
 135 #define nz_value        nlist.n_value
 136 #define nz_desc         nlist.n_desc
 137 #define nz_other        nlist.n_other
 138
 139 /*
 140  * The `section_dispatch_table' structure contains offsets to various data
 141  * structures needed to do run-time relocation.
 142  */
 143 struct section_dispatch_table {
 144         struct so_map *sdt_loaded;      /* List of loaded objects */
 145         long    sdt_sods;               /* List of shared objects descriptors */
 146         long    sdt_paths;              /* Library search paths */
 147         long    sdt_got;                /* Global offset table */
 148         long    sdt_plt;                /* Procedure linkage table */
 149         long    sdt_rel;                /* Relocation table */
 150         long    sdt_hash;               /* Symbol hash table */
 151         long    sdt_nzlist;             /* Symbol table itself */
 152         long    sdt_filler2;            /* Unused (was: stab_hash) */
 153         long    sdt_buckets;            /* Number of hash buckets */
 154         long    sdt_strings;            /* Symbol strings */
 155         long    sdt_str_sz;             /* Size of symbol strings */
 156         long    sdt_text_sz;            /* Size of text area */
 157         long    sdt_plt_sz;             /* Size of procedure linkage table */
 158 };
 159
 160 /*
 161  * RRS symbol hash table, addressed by `sdt_hash' in section_dispatch_table.
 162  * Used to quickly lookup symbols of the shared object by hashing
 163  * on the symbol's name. `rh_symbolnum' is the index of the symbol
 164  * in the shared object's symbol list (`sdt_nzlist'), `rh_next' is
 165  * the next symbol in the hash bucket (in case of collisions).
 166  */
 167 struct rrs_hash {
 168         int     rh_symbolnum;           /* Symbol number */
 169         int     rh_next;                /* Next hash entry */
 170 };
 171
 172 /*
 173  * `rt_symbols' is used to keep track of run-time allocated commons
 174  * and data items copied from shared objects.
 175  */
 176 struct rt_symbol {
 177         struct nzlist           *rt_sp;         /* The symbol */
 178         struct rt_symbol        *rt_next;       /* Next in linear list */
 179         struct rt_symbol        *rt_link;       /* Next in bucket */
 180         caddr_t                 rt_srcaddr;     /* Address of "master" copy */
 181         struct so_map           *rt_smp;        /* Originating map */
 182 };
 183
 184 /*
 185  * Debugger interface structure.
 186  */
 187 struct so_debug {
 188         int     dd_version;             /* Version # of interface */
 189         int     dd_in_debugger;         /* Set when run by debugger */
 190         int     dd_sym_loaded;          /* Run-time linking brought more
 191                                            symbols into scope */
 192         char     *dd_bpt_addr;          /* Address of rtld-generated bpt */
 193         int     dd_bpt_shadow;          /* Original contents of bpt */
 194         struct rt_symbol *dd_cc;        /* Allocated commons/copied data */
 195 };
 196
 197 /*
 198  * Version returned to crt0 from ld.so
 199  */
 200 #define LDSO_VERSION_NONE       0       /* FreeBSD2.0, 2.0.5 */
 201 #define LDSO_VERSION_HAS_DLEXIT 1       /* includes dlexit in ld_entry */
 202 #define LDSO_VERSION_HAS_DLSYM3 2       /* includes 3-argument dlsym */
 203 #define LDSO_VERSION_HAS_DLADDR 3       /* includes dladdr in ld_entry */
 204
 205 /*
 206  * Entry points into ld.so - user interface to the run-time linker.
 207  * Entries are valid for the given version numbers returned by ld.so
 208  * to crt0.
 209  */
 210 struct ld_entry {
 211         void    *(*dlopen) (const char *, int); /* NONE */
 212         int     (*dlclose) (void *);            /* NONE */
 213         void    *(*dlsym) (void *, const char *);       /* NONE */
 214         const char *(*dlerror) (void);          /* NONE */
 215         void    (*dlexit) (void);                       /* HAS_DLEXIT */
 216         void    *(*dlsym3) (void *, const char *, void *); /* HAS_DLSYM3 */
 217         int      (*dladdr) (const void *,
 218                                 struct dl_info *);      /* HAS_DLADDR */
 219 };
 220
 221 /*
 222  * This is the structure pointed at by the __DYNAMIC symbol if an
 223  * executable requires the attention of the run-time link editor.
 224  * __DYNAMIC is given the value zero if no run-time linking needs to
 225  * be done (it is always present in shared objects).
 226  * The union `d_un' provides for different versions of the dynamic
 227  * linking mechanism (switched on by `d_version'). The last version
 228  * used by Sun is 3. We leave some room here and go to version number
 229  * 8 for NetBSD, the main difference lying in the support for the
 230  * `nz_list' type of symbols.
 231  */
 232
 233 struct  _dynamic {
 234         int             d_version;      /* version # of this interface */
 235         struct so_debug *d_debug;
 236         union {
 237                 struct section_dispatch_table *d_sdt;
 238         } d_un;
 239         struct ld_entry *d_entry;       /* XXX */
 240 };
 241
 242 #define LD_VERSION_SUN          (3)
 243 #define LD_VERSION_BSD          (8)
 244 #define LD_VERSION_NZLIST_P(v)  ((v) >= 8)
 245
 246 #define LD_GOT(x)       ((x)->d_un.d_sdt->sdt_got)
 247 #define LD_PLT(x)       ((x)->d_un.d_sdt->sdt_plt)
 248 #define LD_REL(x)       ((x)->d_un.d_sdt->sdt_rel)
 249 #define LD_SYMBOL(x)    ((x)->d_un.d_sdt->sdt_nzlist)
 250 #define LD_HASH(x)      ((x)->d_un.d_sdt->sdt_hash)
 251 #define LD_STRINGS(x)   ((x)->d_un.d_sdt->sdt_strings)
 252 #define LD_NEED(x)      ((x)->d_un.d_sdt->sdt_sods)
 253 #define LD_BUCKETS(x)   ((x)->d_un.d_sdt->sdt_buckets)
 254 #define LD_PATHS(x)     ((x)->d_un.d_sdt->sdt_paths)
 255
 256 #define LD_GOTSZ(x)     ((x)->d_un.d_sdt->sdt_plt - (x)->d_un.d_sdt->sdt_got)
 257 #define LD_RELSZ(x)     ((x)->d_un.d_sdt->sdt_hash - (x)->d_un.d_sdt->sdt_rel)
 258 #define LD_HASHSZ(x)    ((x)->d_un.d_sdt->sdt_nzlist - (x)->d_un.d_sdt->sdt_hash)
 259 #define LD_STABSZ(x)    ((x)->d_un.d_sdt->sdt_strings - (x)->d_un.d_sdt->sdt_nzlist)
 260 #define LD_PLTSZ(x)     ((x)->d_un.d_sdt->sdt_plt_sz)
 261 #define LD_STRSZ(x)     ((x)->d_un.d_sdt->sdt_str_sz)
 262 #define LD_TEXTSZ(x)    ((x)->d_un.d_sdt->sdt_text_sz)
 263
 264 /*
 265  * Interface to ld.so
 266  */
 267 struct crt_ldso {
 268         int             crt_ba;         /* Base address of ld.so */
 269         int             crt_dzfd;       /* "/dev/zero" file descriptor (SunOS) */
 270         int             crt_ldfd;       /* ld.so file descriptor */
 271         struct _dynamic *crt_dp;        /* Main's __DYNAMIC */
 272         char            **crt_ep;       /* environment strings */
 273         caddr_t         crt_bp;         /* Breakpoint if run from debugger */
 274         char            *crt_prog;      /* Program name (v3) */
 275         char            *crt_ldso;      /* Link editor name (v4) */
 276         struct ld_entry *crt_ldentry;   /* dl*() access (v4) */
 277         char            **crt_argv;     /* argument strings (v5) */
 278 };
 279
 280 /*
 281  * Version passed from crt0 to ld.so (1st argument to _rtld()).
 282  */
 283 #define CRT_VERSION_SUN         1
 284 #define CRT_VERSION_BSD_2       2
 285 #define CRT_VERSION_BSD_3       3
 286 #define CRT_VERSION_BSD_4       4
 287 #define CRT_VERSION_BSD_5       5
 288
 289 /*
 290  * Maximum number of recognized shared object version numbers.
 291  */
 292 #define MAXDEWEY        8
 293
 294 /*
 295  * Header of the hints file.
 296  */
 297 struct hints_header {
 298         long            hh_magic;
 299 #define HH_MAGIC        011421044151
 300         long            hh_version;     /* Interface version number */
 301 #define LD_HINTS_VERSION_1      1
 302 #define LD_HINTS_VERSION_2      2
 303         long            hh_hashtab;     /* Location of hash table */
 304         long            hh_nbucket;     /* Number of buckets in hashtab */
 305         long            hh_strtab;      /* Location of strings */
 306         long            hh_strtab_sz;   /* Size of strings */
 307         long            hh_ehints;      /* End of hints (max offset in file) */
 308         long            hh_dirlist;     /* Colon-separated list of srch dirs */
 309 };
 310
 311 #define HH_BADMAG(hdr)  ((hdr).hh_magic != HH_MAGIC)
 312
 313 /*
 314  * Hash table element in hints file.
 315  */
 316 struct hints_bucket {
 317         /* namex and pathx are indices into the string table */
 318         int             hi_namex;               /* Library name */
 319         int             hi_pathx;               /* Full path */
 320         int             hi_dewey[MAXDEWEY];     /* The versions */
 321         int             hi_ndewey;              /* Number of version numbers */
 322 #define hi_major hi_dewey[0]
 323 #define hi_minor hi_dewey[1]
 324         int             hi_next;                /* Next in this bucket */
 325 };
 326
 327 #define _PATH_LD_HINTS          "/var/run/ld.so.hints"
 328
 329 #endif /* !__ELF__ */
 330
 331 #endif /* _LINK_H_ */