mdreloc.c revision 1.19 
1/*	$NetBSD: mdreloc.c,v 1.19 2005/08/20 19:01:17 skrll Exp $	*/
2
3#include <sys/cdefs.h>
4#ifndef lint
5__RCSID("$NetBSD: mdreloc.c,v 1.19 2005/08/20 19:01:17 skrll Exp $");
6#endif /* not lint */
7
8#include <sys/types.h>
9#include <sys/stat.h>
10
11#include "debug.h"
12#include "rtld.h"
13
14void _rtld_bind_start(void);
15void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
16caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
17static inline int _rtld_relocate_plt_object(const Obj_Entry *,
18    const Elf_Rela *, Elf_Addr *);
19
20
21void
22_rtld_setup_pltgot(const Obj_Entry *obj)
23{
24	obj->pltgot[1] = (Elf_Addr) obj;
25	obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
26}
27
28void
29_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
30{
31	const Elf_Rela *rela = 0, *relalim;
32	Elf_Addr relasz = 0;
33	Elf_Addr *where;
34
35	for (; dynp->d_tag != DT_NULL; dynp++) {
36		switch (dynp->d_tag) {
37		case DT_RELA:
38			rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
39			break;
40		case DT_RELASZ:
41			relasz = dynp->d_un.d_val;
42			break;
43		}
44	}
45	relalim = (const Elf_Rela *)((caddr_t)rela + relasz);
46	for (; rela < relalim; rela++) {
47		where = (Elf_Addr *)(relocbase + rela->r_offset);
48		*where += (Elf_Addr)relocbase;
49	}
50}
51
52int
53_rtld_relocate_nonplt_objects(const Obj_Entry *obj)
54{
55	const Elf_Rela *rela;
56
57	for (rela = obj->rela; rela < obj->relalim; rela++) {
58		Elf_Addr        *where;
59		const Elf_Sym   *def;
60		const Obj_Entry *defobj;
61		Elf_Addr         tmp;
62		unsigned long	 symnum;
63
64		where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
65		symnum = ELF_R_SYM(rela->r_info);
66
67		switch (ELF_R_TYPE(rela->r_info)) {
68		case R_TYPE(NONE):
69			break;
70
71#if 1 /* XXX should not occur */
72		case R_TYPE(PC32):
73			def = _rtld_find_symdef(symnum, obj, &defobj, false);
74			if (def == NULL)
75				return -1;
76
77			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
78			    rela->r_addend) - (Elf_Addr)where;
79			if (*where != tmp)
80				*where = tmp;
81			rdbg(("PC32 %s in %s --> %p in %s",
82			    obj->strtab + obj->symtab[symnum].st_name,
83			    obj->path, (void *)*where, defobj->path));
84			break;
85
86		case R_TYPE(GOT32):
87#endif
88		case R_TYPE(32):
89		case R_TYPE(GLOB_DAT):
90			def = _rtld_find_symdef(symnum, obj, &defobj, false);
91			if (def == NULL)
92				return -1;
93
94			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
95			    rela->r_addend);
96			if (*where != tmp)
97				*where = tmp;
98			rdbg(("32/GLOB_DAT %s in %s --> %p in %s",
99			    obj->strtab + obj->symtab[symnum].st_name,
100			    obj->path, (void *)*where, defobj->path));
101			break;
102
103		case R_TYPE(RELATIVE):
104			*where += (Elf_Addr)obj->relocbase;
105			rdbg(("RELATIVE in %s --> %p", obj->path,
106			    (void *)*where));
107			break;
108
109		case R_TYPE(COPY):
110			/*
111			 * These are deferred until all other relocations have
112			 * been done.  All we do here is make sure that the
113			 * COPY relocation is not in a shared library.  They
114			 * are allowed only in executable files.
115			 */
116			if (obj->isdynamic) {
117				_rtld_error(
118			"%s: Unexpected R_COPY relocation in shared library",
119				    obj->path);
120				return -1;
121			}
122			rdbg(("COPY (avoid in main)"));
123			break;
124
125		default:
126			rdbg(("sym = %lu, type = %lu, offset = %p, "
127			    "addend = %p, contents = %p, symbol = %s",
128			    symnum, (u_long)ELF_R_TYPE(rela->r_info),
129			    (void *)rela->r_offset, (void *)rela->r_addend,
130			    (void *)*where,
131			    obj->strtab + obj->symtab[symnum].st_name));
132			_rtld_error("%s: Unsupported relocation type %ld "
133			    "in non-PLT relocations\n",
134			    obj->path, (u_long) ELF_R_TYPE(rela->r_info));
135			return -1;
136		}
137	}
138	return 0;
139}
140
141int
142_rtld_relocate_plt_lazy(const Obj_Entry *obj)
143{
144	const Elf_Rela *rela;
145
146	if (!obj->relocbase)
147		return 0;
148
149	for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
150		Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
151
152		assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
153
154		/* Just relocate the GOT slots pointing into the PLT */
155		*where += (Elf_Addr)obj->relocbase;
156		rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
157	}
158
159	return 0;
160}
161
162static inline int
163_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
164{
165	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
166	Elf_Addr new_value;
167	const Elf_Sym  *def;
168	const Obj_Entry *defobj;
169
170	assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
171
172	def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true);
173	if (def == NULL)
174		return -1;
175
176	assert(rela->r_addend == 0);
177	new_value = (Elf_Addr)(defobj->relocbase + def->st_value +
178	    rela->r_addend);
179	rdbg(("bind now/fixup in %s --> old=%p new=%p",
180	    defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
181	if (*where != new_value)
182		*where = new_value;
183
184	if (tp)
185		*tp = new_value - rela->r_addend;
186
187	return 0;
188}
189
190caddr_t
191_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
192{
193	const Elf_Rela *rela = (const Elf_Rela *)((caddr_t)obj->pltrela + reloff);
194	Elf_Addr result;
195	int err;
196
197	err = _rtld_relocate_plt_object(obj, rela, &result);
198	if (err)
199		_rtld_die();
200
201	return (caddr_t)result;
202}
203
204int
205_rtld_relocate_plt_objects(const Obj_Entry *obj)
206{
207	const Elf_Rela *rela;
208
209	for (rela = obj->pltrela; rela < obj->pltrelalim; rela++)
210		if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
211			return -1;
212
213	return 0;
214}
215