mdreloc.c revision 1.18 
1/*	$NetBSD: mdreloc.c,v 1.18 2005/07/26 15:43:34 skrll Exp $	*/
2
3#include <sys/types.h>
4#include <sys/stat.h>
5
6#include "debug.h"
7#include "rtld.h"
8
9void _rtld_bind_start(void);
10void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
11caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
12static inline int _rtld_relocate_plt_object(const Obj_Entry *,
13    const Elf_Rela *, Elf_Addr *);
14
15
16void
17_rtld_setup_pltgot(const Obj_Entry *obj)
18{
19	obj->pltgot[1] = (Elf_Addr) obj;
20	obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
21}
22
23void
24_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
25{
26	const Elf_Rela *rela = 0, *relalim;
27	Elf_Addr relasz = 0;
28	Elf_Addr *where;
29
30	for (; dynp->d_tag != DT_NULL; dynp++) {
31		switch (dynp->d_tag) {
32		case DT_RELA:
33			rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
34			break;
35		case DT_RELASZ:
36			relasz = dynp->d_un.d_val;
37			break;
38		}
39	}
40	relalim = (const Elf_Rela *)((caddr_t)rela + relasz);
41	for (; rela < relalim; rela++) {
42		where = (Elf_Addr *)(relocbase + rela->r_offset);
43		*where += (Elf_Addr)relocbase;
44	}
45}
46
47int
48_rtld_relocate_nonplt_objects(const Obj_Entry *obj)
49{
50	const Elf_Rela *rela;
51
52	for (rela = obj->rela; rela < obj->relalim; rela++) {
53		Elf_Addr        *where;
54		const Elf_Sym   *def;
55		const Obj_Entry *defobj;
56		Elf_Addr         tmp;
57		unsigned long	 symnum;
58
59		where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
60		symnum = ELF_R_SYM(rela->r_info);
61
62		switch (ELF_R_TYPE(rela->r_info)) {
63		case R_TYPE(NONE):
64			break;
65
66#if 1 /* XXX should not occur */
67		case R_TYPE(PC32):
68			def = _rtld_find_symdef(symnum, obj, &defobj, false);
69			if (def == NULL)
70				return -1;
71
72			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
73			    rela->r_addend) - (Elf_Addr)where;
74			if (*where != tmp)
75				*where = tmp;
76			rdbg(("PC32 %s in %s --> %p in %s",
77			    obj->strtab + obj->symtab[symnum].st_name,
78			    obj->path, (void *)*where, defobj->path));
79			break;
80
81		case R_TYPE(GOT32):
82#endif
83		case R_TYPE(32):
84		case R_TYPE(GLOB_DAT):
85			def = _rtld_find_symdef(symnum, obj, &defobj, false);
86			if (def == NULL)
87				return -1;
88
89			tmp = (Elf_Addr)(defobj->relocbase + def->st_value +
90			    rela->r_addend);
91			if (*where != tmp)
92				*where = tmp;
93			rdbg(("32/GLOB_DAT %s in %s --> %p in %s",
94			    obj->strtab + obj->symtab[symnum].st_name,
95			    obj->path, (void *)*where, defobj->path));
96			break;
97
98		case R_TYPE(RELATIVE):
99			*where += (Elf_Addr)obj->relocbase;
100			rdbg(("RELATIVE in %s --> %p", obj->path,
101			    (void *)*where));
102			break;
103
104		case R_TYPE(COPY):
105			/*
106			 * These are deferred until all other relocations have
107			 * been done.  All we do here is make sure that the
108			 * COPY relocation is not in a shared library.  They
109			 * are allowed only in executable files.
110			 */
111			if (obj->isdynamic) {
112				_rtld_error(
113			"%s: Unexpected R_COPY relocation in shared library",
114				    obj->path);
115				return -1;
116			}
117			rdbg(("COPY (avoid in main)"));
118			break;
119
120		default:
121			rdbg(("sym = %lu, type = %lu, offset = %p, "
122			    "addend = %p, contents = %p, symbol = %s",
123			    symnum, (u_long)ELF_R_TYPE(rela->r_info),
124			    (void *)rela->r_offset, (void *)rela->r_addend,
125			    (void *)*where,
126			    obj->strtab + obj->symtab[symnum].st_name));
127			_rtld_error("%s: Unsupported relocation type %ld "
128			    "in non-PLT relocations\n",
129			    obj->path, (u_long) ELF_R_TYPE(rela->r_info));
130			return -1;
131		}
132	}
133	return 0;
134}
135
136int
137_rtld_relocate_plt_lazy(const Obj_Entry *obj)
138{
139	const Elf_Rela *rela;
140
141	if (!obj->relocbase)
142		return 0;
143
144	for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
145		Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
146
147		assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
148
149		/* Just relocate the GOT slots pointing into the PLT */
150		*where += (Elf_Addr)obj->relocbase;
151		rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
152	}
153
154	return 0;
155}
156
157static inline int
158_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
159{
160	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
161	Elf_Addr new_value;
162	const Elf_Sym  *def;
163	const Obj_Entry *defobj;
164
165	assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));
166
167	def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true);
168	if (def == NULL)
169		return -1;
170
171	assert(rela->r_addend == 0);
172	new_value = (Elf_Addr)(defobj->relocbase + def->st_value +
173	    rela->r_addend);
174	rdbg(("bind now/fixup in %s --> old=%p new=%p",
175	    defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
176	if (*where != new_value)
177		*where = new_value;
178
179	if (tp)
180		*tp = new_value - rela->r_addend;
181
182	return 0;
183}
184
185caddr_t
186_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
187{
188	const Elf_Rela *rela = (const Elf_Rela *)((caddr_t)obj->pltrela + reloff);
189	Elf_Addr result;
190	int err;
191
192	err = _rtld_relocate_plt_object(obj, rela, &result);
193	if (err)
194		_rtld_die();
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