1/*	$NetBSD: mdreloc.c,v 1.29 2011/03/12 22:54:36 joerg Exp $	*/
2
3#include <sys/cdefs.h>
4#ifndef lint
5__RCSID("$NetBSD: mdreloc.c,v 1.29 2011/03/12 22:54:36 joerg Exp $");
6#endif /* not lint */
7
8#include <sys/cdefs.h>
9#ifndef lint
10__RCSID("$NetBSD: mdreloc.c,v 1.29 2011/03/12 22:54:36 joerg Exp $");
11#endif /* not lint */
12
13#include <sys/types.h>
14#include <sys/tls.h>
15
16#include "debug.h"
17#include "rtld.h"
18
19void _rtld_bind_start(void);
20void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
21caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
22static inline int _rtld_relocate_plt_object(const Obj_Entry *,
23    const Elf_Rela *, Elf_Addr *);
24
25void
26_rtld_setup_pltgot(const Obj_Entry *obj)
27{
28	obj->pltgot[1] = (Elf_Addr) obj;
29	obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
30}
31
32void
33_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
34{
35	const Elf_Rela *rela = 0, *relalim;
36	Elf_Addr relasz = 0;
37	Elf_Addr *where;
38
39	for (; dynp->d_tag != DT_NULL; dynp++) {
40		switch (dynp->d_tag) {
41		case DT_RELA:
42			rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
43			break;
44		case DT_RELASZ:
45			relasz = dynp->d_un.d_val;
46			break;
47		}
48	}
49	relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
50	for (; rela < relalim; rela++) {
51		where = (Elf_Addr *)(relocbase + rela->r_offset);
52		*where = (Elf_Addr)(relocbase + rela->r_addend);
53	}
54}
55
56int
57_rtld_relocate_nonplt_objects(Obj_Entry *obj)
58{
59	const Elf_Rela *rela;
60
61	for (rela = obj->rela; rela < obj->relalim; rela++) {
62		Elf_Addr        *where;
63		const Elf_Sym   *def;
64		const Obj_Entry *defobj;
65		Elf_Addr         tmp;
66		unsigned long	 symnum;
67
68		where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
69		symnum = ELF_R_SYM(rela->r_info);
70
71		switch (ELF_R_TYPE(rela->r_info)) {
72		case R_TYPE(NONE):
73			break;
74
75#if 1 /* XXX should not occur */
76		case R_TYPE(GOT32):
77			def = _rtld_find_symdef(symnum, obj, &defobj, false);
78			if (def == NULL)
79				return -1;
80
81			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
82			    rela->r_addend);
83			if (*where != tmp)
84				*where = tmp;
85			rdbg(("GOT32 %s in %s --> %p in %s",
86			    obj->strtab + obj->symtab[symnum].st_name,
87			    obj->path, (void *)*where, defobj->path));
88			break;
89
90		case R_TYPE(REL32):
91			def = _rtld_find_symdef(symnum, obj, &defobj, false);
92			if (def == NULL)
93				return -1;
94
95			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
96			    rela->r_addend) - (Elf_Addr)where;
97			if (*where != tmp)
98				*where = tmp;
99			rdbg(("PC32 %s in %s --> %p in %s",
100			    obj->strtab + obj->symtab[symnum].st_name,
101			    obj->path, (void *)*where, defobj->path));
102			break;
103#endif
104
105		case R_TYPE(DIR32):
106			def = _rtld_find_symdef(symnum, obj, &defobj, false);
107			if (def == NULL)
108				return -1;
109
110			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
111			    rela->r_addend);
112			if (*where != tmp)
113				*where = tmp;
114			rdbg(("32 %s in %s --> %p in %s",
115			    obj->strtab + obj->symtab[symnum].st_name,
116			    obj->path, (void *)*where, defobj->path));
117			break;
118
119		case R_TYPE(GLOB_DAT):
120			def = _rtld_find_symdef(symnum, obj, &defobj, false);
121			if (def == NULL)
122				return -1;
123
124			tmp = (Elf_Addr)(defobj->relocbase + def->st_value) +
125			    rela->r_addend;
126			if (*where != tmp)
127				*where = tmp;
128			rdbg(("GLOB_DAT %s in %s --> %p in %s",
129			    obj->strtab + obj->symtab[symnum].st_name,
130			    obj->path, (void *)*where, defobj->path));
131			break;
132
133		case R_TYPE(RELATIVE):
134			if (rela->r_addend)
135				*where = (Elf_Addr)obj->relocbase + rela->r_addend;
136			else
137				*where += (Elf_Addr)obj->relocbase;
138			rdbg(("RELATIVE in %s --> %p", obj->path,
139			    (void *)*where));
140			break;
141
142		case R_TYPE(COPY):
143			/*
144			 * These are deferred until all other relocations have
145			 * been done.  All we do here is make sure that the
146			 * COPY relocation is not in a shared library.  They
147			 * are allowed only in executable files.
148			 */
149			if (obj->isdynamic) {
150				_rtld_error(
151			"%s: Unexpected R_COPY relocation in shared library",
152				    obj->path);
153				return -1;
154			}
155			rdbg(("COPY (avoid in main)"));
156			break;
157
158		case R_TYPE(TLS_DTPOFF32):
159			def = _rtld_find_symdef(symnum, obj, &defobj, false);
160			if (def == NULL)
161				return -1;
162
163			*where = (Elf_Addr)(def->st_value);
164
165			rdbg(("TLS_DTPOFF32 %s in %s --> %p",
166			    obj->strtab + obj->symtab[symnum].st_name,
167			    obj->path, (void *)*where));
168
169			break;
170		case R_TYPE(TLS_DTPMOD32):
171			def = _rtld_find_symdef(symnum, obj, &defobj, false);
172			if (def == NULL)
173				return -1;
174
175			*where = (Elf_Addr)(defobj->tlsindex);
176
177			rdbg(("TLS_DTPMOD32 %s in %s --> %p",
178			    obj->strtab + obj->symtab[symnum].st_name,
179			    obj->path, (void *)*where));
180
181			break;
182
183		case R_TYPE(TLS_TPOFF32):
184			def = _rtld_find_symdef(symnum, obj, &defobj, false);
185			if (def == NULL)
186				return -1;
187
188			if (!defobj->tls_done &&
189			    _rtld_tls_offset_allocate(obj))
190				return -1;
191
192			*where = (Elf_Addr)def->st_value +
193			    rela->r_addend + defobj->tlsoffset +
194			    sizeof(struct tls_tcb);
195
196			rdbg(("TLS_TPOFF32 %s in %s --> %p",
197			    obj->strtab + obj->symtab[symnum].st_name,
198			    obj->path, (void *)*where));
199			break;
200
201		default:
202			rdbg(("sym = %lu, type = %lu, offset = %p, "
203			    "addend = %p, contents = %p, symbol = %s",
204			    symnum, (u_long)ELF_R_TYPE(rela->r_info),
205			    (void *)rela->r_offset, (void *)rela->r_addend,
206			    (void *)*where,
207			    obj->strtab + obj->symtab[symnum].st_name));
208			_rtld_error("%s: Unsupported relocation type %ld "
209			    "in non-PLT relocations",
210			    obj->path, (u_long) ELF_R_TYPE(rela->r_info));
211			return -1;
212		}
213	}
214	return 0;
215}
216
217int
218_rtld_relocate_plt_lazy(const Obj_Entry *obj)
219{
220	const Elf_Rela *rela;
221
222	if (!obj->relocbase)
223		return 0;
224
225	for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
226		Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
227
228		assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
229
230		/* Just relocate the GOT slots pointing into the PLT */
231		*where += (Elf_Addr)obj->relocbase;
232		rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
233	}
234
235	return 0;
236}
237
238caddr_t
239_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
240{
241	const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
242	Elf_Addr new_value;
243	int err;
244
245	new_value = 0;	/* XXX gcc */
246
247	_rtld_shared_enter();
248	err = _rtld_relocate_plt_object(obj, rela, &new_value);
249	if (err)
250		_rtld_die();
251	_rtld_shared_exit();
252
253	return (caddr_t)new_value;
254}
255
256int
257_rtld_relocate_plt_objects(const Obj_Entry *obj)
258{
259	const Elf_Rela *rela = obj->pltrela;
260
261	for (; rela < obj->pltrelalim; rela++)
262		if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
263			return -1;
264
265	return 0;
266}
267
268static inline int
269_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
270{
271	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
272	Elf_Addr new_value;
273	const Elf_Sym  *def;
274	const Obj_Entry *defobj;
275	unsigned long info = rela->r_info;
276
277	assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT));
278
279	def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
280	if (__predict_false(def == NULL))
281		return -1;
282	if (__predict_false(def == &_rtld_sym_zero))
283		return 0;
284
285	new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
286	rdbg(("bind now/fixup in %s --> old=%p new=%p",
287	    defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
288	if (*where != new_value)
289		*where = new_value;
290
291	if (tp)
292		*tp = new_value;
293
294	return 0;
295}
296