1/*	$NetBSD: mdreloc.c,v 1.27 2010/08/06 16:33:19 joerg Exp $	*/
2
3#include <sys/cdefs.h>
4#ifndef lint
5__RCSID("$NetBSD: mdreloc.c,v 1.27 2010/08/06 16:33:19 joerg Exp $");
6#endif /* not lint */
7
8#include <sys/cdefs.h>
9#ifndef lint
10__RCSID("$NetBSD: mdreloc.c,v 1.27 2010/08/06 16:33:19 joerg Exp $");
11#endif /* not lint */
12
13#include <sys/types.h>
14
15#include "debug.h"
16#include "rtld.h"
17
18void _rtld_bind_start(void);
19void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
20caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
21static inline int _rtld_relocate_plt_object(const Obj_Entry *,
22    const Elf_Rela *, Elf_Addr *);
23
24void
25_rtld_setup_pltgot(const Obj_Entry *obj)
26{
27	obj->pltgot[1] = (Elf_Addr) obj;
28	obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
29}
30
31void
32_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
33{
34	const Elf_Rela *rela = 0, *relalim;
35	Elf_Addr relasz = 0;
36	Elf_Addr *where;
37
38	for (; dynp->d_tag != DT_NULL; dynp++) {
39		switch (dynp->d_tag) {
40		case DT_RELA:
41			rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
42			break;
43		case DT_RELASZ:
44			relasz = dynp->d_un.d_val;
45			break;
46		}
47	}
48	relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
49	for (; rela < relalim; rela++) {
50		where = (Elf_Addr *)(relocbase + rela->r_offset);
51		*where = (Elf_Addr)(relocbase + rela->r_addend);
52	}
53}
54
55int
56_rtld_relocate_nonplt_objects(Obj_Entry *obj)
57{
58	const Elf_Rela *rela;
59
60	for (rela = obj->rela; rela < obj->relalim; rela++) {
61		Elf_Addr        *where;
62		const Elf_Sym   *def;
63		const Obj_Entry *defobj;
64		Elf_Addr         tmp;
65		unsigned long	 symnum;
66
67		where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
68		symnum = ELF_R_SYM(rela->r_info);
69
70		switch (ELF_R_TYPE(rela->r_info)) {
71		case R_TYPE(NONE):
72			break;
73
74		case R_TYPE(32):	/* word32 S + A */
75		case R_TYPE(GLOB_DAT):	/* word32 S + A */
76			def = _rtld_find_symdef(symnum, obj, &defobj, false);
77			if (def == NULL)
78				return -1;
79
80			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
81			    rela->r_addend);
82
83			if (*where != tmp)
84				*where = tmp;
85			rdbg(("32/GLOB_DAT %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(RELATIVE):	/* word32 B + A */
91			tmp = (Elf_Addr)(obj->relocbase + rela->r_addend);
92			if (*where != tmp)
93				*where = tmp;
94			rdbg(("RELATIVE in %s --> %p", obj->path,
95			    (void *)*where));
96			break;
97
98		case R_TYPE(COPY):
99			/*
100			 * These are deferred until all other relocations have
101			 * been done.  All we do here is make sure that the
102			 * COPY relocation is not in a shared library.  They
103			 * are allowed only in executable files.
104			 */
105			if (obj->isdynamic) {
106				_rtld_error(
107			"%s: Unexpected R_COPY relocation in shared library",
108				    obj->path);
109				return -1;
110			}
111			rdbg(("COPY (avoid in main)"));
112			break;
113
114		default:
115			rdbg(("sym = %lu, type = %lu, offset = %p, "
116			    "addend = %p, contents = %p, symbol = %s",
117			    symnum, (u_long)ELF_R_TYPE(rela->r_info),
118			    (void *)rela->r_offset, (void *)rela->r_addend,
119			    (void *)*where,
120			    obj->strtab + obj->symtab[symnum].st_name));
121			_rtld_error("%s: Unsupported relocation type %ld "
122			    "in non-PLT relocations",
123			    obj->path, (u_long) ELF_R_TYPE(rela->r_info));
124			return -1;
125		}
126	}
127	return 0;
128}
129
130int
131_rtld_relocate_plt_lazy(const Obj_Entry *obj)
132{
133	const Elf_Rela *rela;
134
135	if (!obj->relocbase)
136		return 0;
137
138	for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
139		Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
140
141		assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
142
143		/* Just relocate the GOT slots pointing into the PLT */
144		*where += (Elf_Addr)obj->relocbase;
145		rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
146	}
147
148	return 0;
149}
150
151static inline int
152_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
153{
154	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
155	Elf_Addr new_value;
156	const Elf_Sym  *def;
157	const Obj_Entry *defobj;
158	unsigned long info = rela->r_info;
159
160	assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT));
161
162	def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
163	if (__predict_false(def == NULL))
164		return -1;
165	if (__predict_false(def == &_rtld_sym_zero))
166		return 0;
167
168	new_value = (Elf_Addr)(defobj->relocbase + def->st_value +
169	    rela->r_addend);
170	rdbg(("bind now/fixup in %s --> old=%p new=%p",
171	    defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
172	if (*where != new_value)
173		*where = new_value;
174
175	if (tp)
176		*tp = new_value - rela->r_addend;
177
178	return 0;
179}
180
181caddr_t
182_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
183{
184	const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
185	Elf_Addr result;
186	int err;
187
188	result = 0;	/* XXX gcc */
189
190	_rtld_shared_enter();
191	err = _rtld_relocate_plt_object(obj, rela, &result);
192	if (err)
193		_rtld_die();
194	_rtld_shared_exit();
195
196	return (caddr_t)result;
197}
198
199int
200_rtld_relocate_plt_objects(const Obj_Entry *obj)
201{
202	const Elf_Rela *rela;
203
204	for (rela = obj->pltrela; rela < obj->pltrelalim; rela++)
205		if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
206			return -1;
207
208	return 0;
209}
210