xref: /freebsd/sys/sys/linker.h (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 1997-2000 Doug Rabson
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #ifndef _SYS_LINKER_H_
30 #define _SYS_LINKER_H_
31 
32 #include <sys/param.h>
33 
34 #ifdef _KERNEL
35 
36 #include <machine/elf.h>
37 #include <sys/kobj.h>
38 
39 #ifdef MALLOC_DECLARE
40 MALLOC_DECLARE(M_LINKER);
41 #endif
42 
43 struct mod_depend;
44 
45 /*
46  * Object representing a file which has been loaded by the linker.
47  */
48 typedef struct linker_file* linker_file_t;
49 typedef TAILQ_HEAD(, linker_file) linker_file_list_t;
50 
51 typedef caddr_t linker_sym_t;		/* opaque symbol */
52 typedef c_caddr_t c_linker_sym_t;	/* const opaque symbol */
53 typedef int (*linker_function_name_callback_t)(const char *, void *);
54 
55 /*
56  * expanded out linker_sym_t
57  */
58 typedef struct linker_symval {
59     const char*		name;
60     caddr_t		value;
61     size_t		size;
62 } linker_symval_t;
63 
64 typedef int (*linker_function_nameval_callback_t)(linker_file_t, int, linker_symval_t *, void *);
65 
66 struct common_symbol {
67     STAILQ_ENTRY(common_symbol) link;
68     char*		name;
69     caddr_t		address;
70 };
71 
72 struct linker_file {
73     KOBJ_FIELDS;
74     int			refs;		/* reference count */
75     int			userrefs;	/* kldload(2) count */
76     int			flags;
77 #define LINKER_FILE_LINKED	0x1	/* file has been fully linked */
78 #define LINKER_FILE_MODULES	0x2	/* file has >0 modules at preload */
79     TAILQ_ENTRY(linker_file) link;	/* list of all loaded files */
80     char*		filename;	/* file which was loaded */
81     char*		pathname;	/* file name with full path */
82     int			id;		/* unique id */
83     caddr_t		address;	/* load address */
84     size_t		size;		/* size of file */
85     caddr_t		ctors_addr;	/* address of .ctors/.init_array */
86     size_t		ctors_size;	/* size of .ctors/.init_array */
87     enum {
88 	    LF_NONE = 0,
89 	    LF_CTORS,
90 	    LF_DTORS,
91     } ctors_invoked;			/* have we run ctors yet? */
92     caddr_t		dtors_addr;	/* address of .dtors/.fini_array */
93     size_t		dtors_size;	/* size of .dtors/.fini_array */
94     int			ndeps;		/* number of dependencies */
95     linker_file_t*	deps;		/* list of dependencies */
96     STAILQ_HEAD(, common_symbol) common; /* list of common symbols */
97     TAILQ_HEAD(, module) modules;	/* modules in this file */
98     TAILQ_ENTRY(linker_file) loaded;	/* preload dependency support */
99     int			loadcnt;	/* load counter value */
100 
101     /*
102      * Function Boundary Tracing (FBT) or Statically Defined Tracing (SDT)
103      * fields.
104      */
105     int			nenabled;	/* number of enabled probes. */
106     int			fbt_nentries;	/* number of fbt entries created. */
107 
108 #ifdef __arm__
109     caddr_t		exidx_addr;	/* Unwind data index table start */
110     size_t		exidx_size;	/* Unwind data index table size */
111 #endif
112 };
113 
114 /*
115  * Object implementing a class of file (a.out, elf, etc.)
116  */
117 typedef struct linker_class *linker_class_t;
118 typedef TAILQ_HEAD(, linker_class) linker_class_list_t;
119 
120 struct linker_class {
121     KOBJ_CLASS_FIELDS;
122     TAILQ_ENTRY(linker_class) link;	/* list of all file classes */
123 };
124 
125 /*
126  * Function type used when iterating over the list of linker files.
127  */
128 typedef int linker_predicate_t(linker_file_t, void *);
129 
130 /*
131  * The "file" for the kernel.
132  */
133 extern linker_file_t	linker_kernel_file;
134 
135 /*
136  * Special symbol which will be replaced by a reference to the linker_file_t
137  * of the module it is used in.
138  */
139 extern linker_file_t __this_linker_file;
140 
141 /*
142  * Obtain a reference to a module, loading it if required.
143  */
144 int linker_reference_module(const char* _modname, struct mod_depend *_verinfo,
145 			    linker_file_t* _result);
146 
147 /*
148  * Release a reference to a module, unloading it if there are no more
149  * references.  Note that one should either provide a module name and
150  * optional version info or a linker file, but not both.
151  */
152 int linker_release_module(const char *_modname, struct mod_depend *_verinfo,
153 			  linker_file_t _file);
154 
155 /*
156  * Iterate over all of the currently loaded linker files calling the
157  * predicate function while the function returns 0.  Returns the value
158  * returned by the last predicate function.
159  */
160 int linker_file_foreach(linker_predicate_t *_predicate, void *_context);
161 
162 /*
163  * Lookup a symbol in a file.  If deps is TRUE, look in dependencies
164  * if not found in file.
165  */
166 caddr_t linker_file_lookup_symbol(linker_file_t _file, const char* _name,
167 				  int _deps);
168 
169 /*
170  * Lookup a linker set in a file.  Return pointers to the first entry,
171  * last + 1, and count of entries.  Use: for (p = start; p < stop; p++) {}
172  * void *start is really: "struct yoursetmember ***start;"
173  */
174 int linker_file_lookup_set(linker_file_t _file, const char *_name,
175 			   void *_start, void *_stop, int *_count);
176 
177 /*
178  * List all functions in a file.
179  */
180 int linker_file_function_listall(linker_file_t,
181 				 linker_function_nameval_callback_t, void *);
182 
183 /*
184  * Functions solely for use by the linker class handlers.
185  */
186 int linker_add_class(linker_class_t _cls);
187 int linker_file_unload(linker_file_t _file, int flags);
188 int linker_load_dependencies(linker_file_t _lf);
189 linker_file_t linker_make_file(const char* _filename, linker_class_t _cls);
190 
191 /*
192  * DDB Helpers, tuned specifically for ddb/db_kld.c
193  */
194 int linker_ddb_lookup(const char *_symstr, c_linker_sym_t *_sym);
195 int linker_ddb_search_symbol(caddr_t _value, c_linker_sym_t *_sym,
196 			     long *_diffp);
197 int linker_ddb_symbol_values(c_linker_sym_t _sym, linker_symval_t *_symval);
198 int linker_ddb_search_symbol_name(caddr_t value, char *buf, u_int buflen,
199 				  long *offset);
200 
201 /*
202  * stack(9) helper for situations where kernel locking is required.
203  */
204 int linker_search_symbol_name_flags(caddr_t value, char *buf, u_int buflen,
205     long *offset, int flags);
206 int linker_search_symbol_name(caddr_t value, char *buf, u_int buflen,
207     long *offset);
208 
209 /* HWPMC helper */
210 void *linker_hwpmc_list_objects(void);
211 
212 /* kldload/kldunload syscalls blocking */
213 #define	LINKER_UB_UNLOCK	0x0001	/* busy: unlock kld_sx locked on
214 					   return */
215 #define	LINKER_UB_LOCKED	0x0002	/* busy/unbusy: kld_sx locked on
216 					   entry */
217 #define	LINKER_UB_PCATCH	0x0004	/* busy: sleep interruptible */
218 int linker_kldload_busy(int flags);
219 void linker_kldload_unbusy(int flags);
220 
221 #endif	/* _KERNEL */
222 
223 /*
224  * Module information subtypes
225  */
226 #define MODINFO_END		0x0000		/* End of list */
227 #define MODINFO_NAME		0x0001		/* Name of module (string) */
228 #define MODINFO_TYPE		0x0002		/* Type of module (string) */
229 #define MODINFO_ADDR		0x0003		/* Loaded address */
230 #define MODINFO_SIZE		0x0004		/* Size of module */
231 #define MODINFO_EMPTY		0x0005		/* Has been deleted */
232 #define MODINFO_ARGS		0x0006		/* Parameters string */
233 #define MODINFO_METADATA	0x8000		/* Module-specfic */
234 
235 #define MODINFOMD_AOUTEXEC	0x0001		/* a.out exec header */
236 #define MODINFOMD_ELFHDR	0x0002		/* ELF header */
237 #define MODINFOMD_SSYM		0x0003		/* start of symbols */
238 #define MODINFOMD_ESYM		0x0004		/* end of symbols */
239 #define MODINFOMD_DYNAMIC	0x0005		/* _DYNAMIC pointer */
240 #define MODINFOMD_MB2HDR	0x0006		/* MB2 header info */
241 /* These values are MD on PowerPC */
242 #if !defined(__powerpc__)
243 #define MODINFOMD_ENVP		0x0006		/* envp[] */
244 #define MODINFOMD_HOWTO		0x0007		/* boothowto */
245 #define MODINFOMD_KERNEND	0x0008		/* kernend */
246 #endif
247 #define MODINFOMD_SHDR		0x0009		/* section header table */
248 #define MODINFOMD_CTORS_ADDR	0x000a		/* address of .ctors */
249 #define MODINFOMD_CTORS_SIZE	0x000b		/* size of .ctors */
250 #define MODINFOMD_FW_HANDLE	0x000c		/* Firmware dependent handle */
251 #define MODINFOMD_KEYBUF	0x000d		/* Crypto key intake buffer */
252 #define MODINFOMD_FONT		0x000e		/* Console font */
253 #define MODINFOMD_SPLASH	0x000f		/* Console splash screen */
254 #define MODINFOMD_NOCOPY	0x8000		/* don't copy this metadata to the kernel */
255 
256 #define MODINFOMD_DEPLIST	(0x4001 | MODINFOMD_NOCOPY)	/* depends on */
257 
258 #ifdef _KERNEL
259 #define MD_FETCH(mdp, info, type) ({ \
260 	type *__p; \
261 	__p = (type *)preload_search_info((mdp), MODINFO_METADATA | (info)); \
262 	__p ? *__p : 0; \
263 })
264 #endif
265 
266 #define	LINKER_HINTS_VERSION	1		/* linker.hints file version */
267 #define	LINKER_HINTS_MAX	(1 << 20)	/* Allow at most 1MB for linker.hints */
268 
269 #ifdef _KERNEL
270 
271 /*
272  * Module lookup
273  */
274 extern vm_offset_t	preload_addr_relocate;
275 extern caddr_t		preload_metadata;
276 
277 extern void *		preload_fetch_addr(caddr_t _mod);
278 extern size_t		preload_fetch_size(caddr_t _mod);
279 extern caddr_t		preload_search_by_name(const char *_name);
280 extern caddr_t		preload_search_by_type(const char *_type);
281 extern caddr_t		preload_search_next_name(caddr_t _base);
282 extern caddr_t		preload_search_info(caddr_t _mod, int _inf);
283 extern void		preload_delete_name(const char *_name);
284 extern void		preload_bootstrap_relocate(vm_offset_t _offset);
285 extern void		preload_dump(void);
286 
287 #ifdef KLD_DEBUG
288 
289 extern int kld_debug;
290 #define KLD_DEBUG_FILE	1	/* file load/unload */
291 #define KLD_DEBUG_SYM	2	/* symbol lookup */
292 
293 #define KLD_DPF(cat, args)					\
294 	do {							\
295 		if (kld_debug & KLD_DEBUG_##cat) printf args;	\
296 	} while (0)
297 
298 #else
299 
300 #define KLD_DPF(cat, args)
301 
302 #endif
303 
304 typedef int elf_lookup_fn(linker_file_t, Elf_Size, int, Elf_Addr *);
305 
306 /* Support functions */
307 bool	elf_is_ifunc_reloc(Elf_Size r_info);
308 int	elf_reloc(linker_file_t _lf, Elf_Addr base, const void *_rel,
309 	    int _type, elf_lookup_fn _lu);
310 int	elf_reloc_local(linker_file_t _lf, Elf_Addr base, const void *_rel,
311 	    int _type, elf_lookup_fn _lu);
312 Elf_Addr elf_relocaddr(linker_file_t _lf, Elf_Addr addr);
313 const Elf_Sym *elf_get_sym(linker_file_t _lf, Elf_Size _symidx);
314 const char *elf_get_symname(linker_file_t _lf, Elf_Size _symidx);
315 void	link_elf_ireloc(caddr_t kmdp);
316 
317 #if defined(__aarch64__) || defined(__amd64__)
318 int	elf_reloc_late(linker_file_t _lf, Elf_Addr base, const void *_rel,
319 	    int _type, elf_lookup_fn _lu);
320 void	link_elf_late_ireloc(void);
321 #endif
322 
323 typedef struct linker_ctf {
324 	const uint8_t 	*ctftab;	/* Decompressed CTF data. */
325 	int 		ctfcnt;		/* Number of CTF data bytes. */
326 	const Elf_Sym	*symtab;	/* Ptr to the symbol table. */
327 	int		nsym;		/* Number of symbols. */
328 	const char	*strtab;	/* Ptr to the string table. */
329 	int 		strcnt;		/* Number of string bytes. */
330 	uint32_t	**ctfoffp;	/* Ptr to array of obj/fnc offsets. */
331 	uint32_t	**typoffp;	/* Ptr to array of type offsets. */
332 	long		*typlenp;	/* Ptr to number of type data entries. */
333 } linker_ctf_t;
334 
335 int	linker_ctf_get(linker_file_t, linker_ctf_t *);
336 int linker_ctf_lookup_sym_ddb(const char *symname, c_linker_sym_t *sym,
337     linker_ctf_t *lc);
338 int linker_ctf_lookup_typename_ddb(linker_ctf_t *lc, const char *typename);
339 
340 int elf_cpu_load_file(linker_file_t);
341 int elf_cpu_unload_file(linker_file_t);
342 int elf_cpu_parse_dynamic(caddr_t, Elf_Dyn *);
343 
344 /* values for type */
345 #define ELF_RELOC_REL	1
346 #define ELF_RELOC_RELA	2
347 
348 /*
349  * This is version 1 of the KLD file status structure. It is identified
350  * by its _size_ in the version field.
351  */
352 struct kld_file_stat_1 {
353     int		version;	/* set to sizeof(struct kld_file_stat_1) */
354     char        name[MAXPATHLEN];
355     int		refs;
356     int		id;
357     caddr_t	address;	/* load address */
358     size_t	size;		/* size in bytes */
359 };
360 #endif /* _KERNEL */
361 
362 struct kld_file_stat {
363     int		version;	/* set to sizeof(struct kld_file_stat) */
364     char        name[MAXPATHLEN];
365     int		refs;
366     int		id;
367     caddr_t	address;	/* load address */
368     size_t	size;		/* size in bytes */
369     char        pathname[MAXPATHLEN];
370 };
371 
372 struct kld_sym_lookup {
373     int		version;	/* set to sizeof(struct kld_sym_lookup) */
374     char	*symname;	/* Symbol name we are looking up */
375     u_long	symvalue;
376     size_t	symsize;
377 };
378 #define KLDSYM_LOOKUP	1
379 
380 /*
381  * Flags for kldunloadf() and linker_file_unload()
382  */
383 #define LINKER_UNLOAD_NORMAL	0
384 #define LINKER_UNLOAD_FORCE	1
385 
386 #ifndef _KERNEL
387 
388 #include <sys/cdefs.h>
389 
390 __BEGIN_DECLS
391 int	kldload(const char* _file);
392 int	kldunload(int _fileid);
393 int	kldunloadf(int _fileid, int flags);
394 int	kldfind(const char* _file);
395 int	kldnext(int _fileid);
396 int	kldstat(int _fileid, struct kld_file_stat* _stat);
397 int	kldfirstmod(int _fileid);
398 int	kldsym(int _fileid, int _cmd, void *_data);
399 __END_DECLS
400 
401 #endif
402 
403 #endif /* !_SYS_LINKER_H_ */
404