rtld.h revision 142645
1/*-
2 * Copyright 1996, 1997, 1998, 1999, 2000 John D. Polstra.
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 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 *
25 * $FreeBSD: head/libexec/rtld-elf/rtld.h 142645 2005-02-27 12:55:40Z dfr $
26 */
27
28#ifndef RTLD_H /* { */
29#define RTLD_H 1
30
31#include <machine/elf.h>
32#include <sys/types.h>
33#include <sys/queue.h>
34
35#include <elf-hints.h>
36#include <link.h>
37#include <stddef.h>
38
39#include "rtld_lock.h"
40#include "rtld_machdep.h"
41
42#ifdef COMPAT_32BIT
43#undef STANDARD_LIBRARY_PATH
44#undef _PATH_ELF_HINTS
45#define	_PATH_ELF_HINTS		"/var/run/ld-elf32.so.hints"
46/* For running 32 bit binaries  */
47#define	STANDARD_LIBRARY_PATH	"/lib32:/usr/lib32"
48#define LD_ "LD_32_"
49#endif
50
51#ifndef STANDARD_LIBRARY_PATH
52#define STANDARD_LIBRARY_PATH	"/lib:/usr/lib"
53#endif
54#ifndef LD_
55#define LD_ "LD_"
56#endif
57
58#define NEW(type)	((type *) xmalloc(sizeof(type)))
59#define CNEW(type)	((type *) xcalloc(sizeof(type)))
60
61/* We might as well do booleans like C++. */
62typedef unsigned char bool;
63#define false	0
64#define true	1
65
66extern size_t tls_last_offset;
67extern size_t tls_last_size;
68extern size_t tls_static_space;
69extern int tls_dtv_generation;
70extern int tls_max_index;
71
72struct stat;
73struct Struct_Obj_Entry;
74
75/* Lists of shared objects */
76typedef struct Struct_Objlist_Entry {
77    STAILQ_ENTRY(Struct_Objlist_Entry) link;
78    struct Struct_Obj_Entry *obj;
79} Objlist_Entry;
80
81typedef STAILQ_HEAD(Struct_Objlist, Struct_Objlist_Entry) Objlist;
82
83/* Types of init and fini functions */
84typedef void (*InitFunc)(void);
85
86/* Lists of shared object dependencies */
87typedef struct Struct_Needed_Entry {
88    struct Struct_Needed_Entry *next;
89    struct Struct_Obj_Entry *obj;
90    unsigned long name;		/* Offset of name in string table */
91} Needed_Entry;
92
93/* Lock object */
94typedef struct Struct_LockInfo {
95    void *context;		/* Client context for creating locks */
96    void *thelock;		/* The one big lock */
97    /* Debugging aids. */
98    volatile int rcount;	/* Number of readers holding lock */
99    volatile int wcount;	/* Number of writers holding lock */
100    /* Methods */
101    void *(*lock_create)(void *context);
102    void (*rlock_acquire)(void *lock);
103    void (*wlock_acquire)(void *lock);
104    void (*rlock_release)(void *lock);
105    void (*wlock_release)(void *lock);
106    void (*lock_destroy)(void *lock);
107    void (*context_destroy)(void *context);
108} LockInfo;
109
110/*
111 * Shared object descriptor.
112 *
113 * Items marked with "(%)" are dynamically allocated, and must be freed
114 * when the structure is destroyed.
115 *
116 * CAUTION: It appears that the JDK port peeks into these structures.
117 * It looks at "next" and "mapbase" at least.  Don't add new members
118 * near the front, until this can be straightened out.
119 */
120typedef struct Struct_Obj_Entry {
121    /*
122     * These two items have to be set right for compatibility with the
123     * original ElfKit crt1.o.
124     */
125    Elf_Word magic;		/* Magic number (sanity check) */
126    Elf_Word version;		/* Version number of struct format */
127
128    struct Struct_Obj_Entry *next;
129    char *path;			/* Pathname of underlying file (%) */
130    char *origin_path;		/* Directory path of origin file */
131    int refcount;
132    int dl_refcount;		/* Number of times loaded by dlopen */
133
134    /* These items are computed by map_object() or by digest_phdr(). */
135    caddr_t mapbase;		/* Base address of mapped region */
136    size_t mapsize;		/* Size of mapped region in bytes */
137    size_t textsize;		/* Size of text segment in bytes */
138    Elf_Addr vaddrbase;		/* Base address in shared object file */
139    caddr_t relocbase;		/* Relocation constant = mapbase - vaddrbase */
140    const Elf_Dyn *dynamic;	/* Dynamic section */
141    caddr_t entry;		/* Entry point */
142    const Elf_Phdr *phdr;	/* Program header if it is mapped, else NULL */
143    size_t phsize;		/* Size of program header in bytes */
144    const char *interp;		/* Pathname of the interpreter, if any */
145
146    /* TLS information */
147    int tlsindex;		/* Index in DTV for this module */
148    void *tlsinit;		/* Base address of TLS init block */
149    size_t tlsinitsize;		/* Size of TLS init block for this module */
150    size_t tlssize;		/* Size of TLS block for this module */
151    size_t tlsoffset;		/* Offset of static TLS block for this module */
152    size_t tlsalign;		/* Alignment of static TLS block */
153
154    /* Items from the dynamic section. */
155    Elf_Addr *pltgot;		/* PLT or GOT, depending on architecture */
156    const Elf_Rel *rel;		/* Relocation entries */
157    unsigned long relsize;	/* Size in bytes of relocation info */
158    const Elf_Rela *rela;	/* Relocation entries with addend */
159    unsigned long relasize;	/* Size in bytes of addend relocation info */
160    const Elf_Rel *pltrel;	/* PLT relocation entries */
161    unsigned long pltrelsize;	/* Size in bytes of PLT relocation info */
162    const Elf_Rela *pltrela;	/* PLT relocation entries with addend */
163    unsigned long pltrelasize;	/* Size in bytes of PLT addend reloc info */
164    const Elf_Sym *symtab;	/* Symbol table */
165    const char *strtab;		/* String table */
166    unsigned long strsize;	/* Size in bytes of string table */
167
168    const Elf_Hashelt *buckets;	/* Hash table buckets array */
169    unsigned long nbuckets;	/* Number of buckets */
170    const Elf_Hashelt *chains;	/* Hash table chain array */
171    unsigned long nchains;	/* Number of chains */
172
173    const char *rpath;		/* Search path specified in object */
174    Needed_Entry *needed;	/* Shared objects needed by this one (%) */
175
176    Elf_Addr init;		/* Initialization function to call */
177    Elf_Addr fini;		/* Termination function to call */
178
179    bool mainprog;		/* True if this is the main program */
180    bool rtld;			/* True if this is the dynamic linker */
181    bool textrel;		/* True if there are relocations to text seg */
182    bool symbolic;		/* True if generated with "-Bsymbolic" */
183    bool bind_now;		/* True if all relocations should be made first */
184    bool traced;		/* Already printed in ldd trace output */
185    bool jmpslots_done;		/* Already have relocated the jump slots */
186    bool init_done;		/* Already have added object to init list */
187    bool tls_done;		/* Already allocated offset for static TLS */
188
189    struct link_map linkmap;	/* for GDB and dlinfo() */
190    Objlist dldags;		/* Object belongs to these dlopened DAGs (%) */
191    Objlist dagmembers;		/* DAG has these members (%) */
192    dev_t dev;			/* Object's filesystem's device */
193    ino_t ino;			/* Object's inode number */
194    void *priv;			/* Platform-dependant */
195} Obj_Entry;
196
197#define RTLD_MAGIC	0xd550b87a
198#define RTLD_VERSION	1
199
200#define RTLD_STATIC_TLS_EXTRA	64
201
202/*
203 * Symbol cache entry used during relocation to avoid multiple lookups
204 * of the same symbol.
205 */
206typedef struct Struct_SymCache {
207    const Elf_Sym *sym;		/* Symbol table entry */
208    const Obj_Entry *obj;	/* Shared object which defines it */
209} SymCache;
210
211extern void _rtld_error(const char *, ...) __printflike(1, 2);
212extern Obj_Entry *map_object(int, const char *, const struct stat *);
213extern void *xcalloc(size_t);
214extern void *xmalloc(size_t);
215extern char *xstrdup(const char *);
216extern Elf_Addr _GLOBAL_OFFSET_TABLE_[];
217
218extern void dump_relocations (Obj_Entry *);
219extern void dump_obj_relocations (Obj_Entry *);
220extern void dump_Elf_Rel (Obj_Entry *, const Elf_Rel *, u_long);
221extern void dump_Elf_Rela (Obj_Entry *, const Elf_Rela *, u_long);
222
223/*
224 * Function declarations.
225 */
226unsigned long elf_hash(const char *);
227const Elf_Sym *find_symdef(unsigned long, const Obj_Entry *,
228  const Obj_Entry **, bool, SymCache *);
229void init_pltgot(Obj_Entry *);
230void lockdflt_init(void);
231void obj_free(Obj_Entry *);
232Obj_Entry *obj_new(void);
233void _rtld_bind_start(void);
234const Elf_Sym *symlook_obj(const char *, unsigned long,
235  const Obj_Entry *, bool);
236void *tls_get_addr_common(Elf_Addr** dtvp, int index, size_t offset);
237void *allocate_tls(Obj_Entry *, void *, size_t, size_t);
238void free_tls(void *, size_t, size_t);
239void *allocate_module_tls(int index);
240bool allocate_tls_offset(Obj_Entry *obj);
241void free_tls_offset(Obj_Entry *obj);
242
243/*
244 * MD function declarations.
245 */
246int do_copy_relocations(Obj_Entry *);
247int reloc_non_plt(Obj_Entry *, Obj_Entry *);
248int reloc_plt(Obj_Entry *);
249int reloc_jmpslots(Obj_Entry *);
250void allocate_initial_tls(Obj_Entry *);
251
252#endif /* } */
253