1/* $NetBSD: mdreloc.c,v 1.41 2018/04/03 21:10:27 joerg Exp $ */
2
3#include <sys/cdefs.h>
4#ifndef lint
5__RCSID("$NetBSD: mdreloc.c,v 1.41 2018/04/03 21:10:27 joerg Exp $");
6#endif /* not lint */
7
8#include <sys/types.h>
9#include <sys/ucontext.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);
17
18void
19_rtld_setup_pltgot(const Obj_Entry *obj)
20{
21 obj->pltgot[1] = (Elf_Addr) obj;
22 obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
23}
24
25void
26_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
27{
28 const Elf_Rel *rel = 0, *rellim;
29 Elf_Addr relsz = 0;
30 Elf_Addr *where;
31
32 for (; dynp->d_tag != DT_NULL; dynp++) {
33 switch (dynp->d_tag) {
34 case DT_REL:
35 rel = (const Elf_Rel *)(relocbase + dynp->d_un.d_ptr);
36 break;
37 case DT_RELSZ:
38 relsz = dynp->d_un.d_val;
39 break;
40 }
41 }
42 if (rel == 0 || relsz == 0)
43 return;
44 rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz);
45 for (; rel < rellim; rel++) {
46 where = (Elf_Addr *)(relocbase + rel->r_offset);
47 *where += (Elf_Addr)relocbase;
48 }
49}
50
51int
52_rtld_relocate_nonplt_objects(Obj_Entry *obj)
53{
54 const Elf_Rel *rel;
55 Elf_Addr target = 0;
56 const Elf_Sym *def = NULL;
57 const Obj_Entry *defobj = NULL;
58 unsigned long last_symnum = ULONG_MAX;
59
60 for (rel = obj->rel; rel < obj->rellim; rel++) {
61 Elf_Addr *where;
62 Elf_Addr tmp;
63 unsigned long symnum;
64
65 where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
66
67 switch (ELF_R_TYPE(rel->r_info)) {
68 case R_TYPE(PC32):
69 case R_TYPE(GOT32):
70 case R_TYPE(32):
71 case R_TYPE(GLOB_DAT):
72 case R_TYPE(TLS_TPOFF):
73 case R_TYPE(TLS_TPOFF32):
74 case R_TYPE(TLS_DTPMOD32):
75 case R_TYPE(TLS_DTPOFF32):
76 symnum = ELF_R_SYM(rel->r_info);
77 if (symnum != last_symnum) {
78 last_symnum = symnum;
79 def = _rtld_find_symdef(symnum, obj, &defobj,
80 false);
81 if (def == NULL)
82 return -1;
83 }
84 break;
85 default:
86 break;
87 }
88
89
90 switch (ELF_R_TYPE(rel->r_info)) {
91 case R_TYPE(NONE):
92 break;
93
94#if 1 /* XXX should not occur */
95 case R_TYPE(PC32):
96 target = (Elf_Addr)(defobj->relocbase + def->st_value);
97
98 *where += target - (Elf_Addr)where;
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
104 case R_TYPE(GOT32):
105#endif
106 case R_TYPE(32):
107 case R_TYPE(GLOB_DAT):
108 target = (Elf_Addr)(defobj->relocbase + def->st_value);
109
110 tmp = target + *where;
111 if (*where != tmp)
112 *where = tmp;
113 rdbg(("32/GLOB_DAT %s in %s --> %p in %s",
114 obj->strtab + obj->symtab[symnum].st_name,
115 obj->path, (void *)*where, defobj->path));
116 break;
117
118
119 case R_TYPE(IRELATIVE):
120 /* IFUNC relocations are handled in _rtld_call_ifunc */
121 if (obj->ifunc_remaining_nonplt == 0) {
122 obj->ifunc_remaining_nonplt =
123 obj->rellim - rel;
124 }
125 /* FALL-THROUGH */
126
127 case R_TYPE(RELATIVE):
128 *where += (Elf_Addr)obj->relocbase;
129 rdbg(("RELATIVE in %s --> %p", obj->path,
130 (void *)*where));
131 break;
132
133 case R_TYPE(COPY):
134 /*
135 * These are deferred until all other relocations have
136 * been done. All we do here is make sure that the
137 * COPY relocation is not in a shared library. They
138 * are allowed only in executable files.
139 */
140 if (obj->isdynamic) {
141 _rtld_error(
142 "%s: Unexpected R_COPY relocation in shared library",
143 obj->path);
144 return -1;
145 }
146 rdbg(("COPY (avoid in main)"));
147 break;
148
149 case R_TYPE(TLS_TPOFF):
150 if (!defobj->tls_done &&
151 _rtld_tls_offset_allocate(obj))
152 return -1;
153
154 *where += (Elf_Addr)(def->st_value - defobj->tlsoffset);
155
156 rdbg(("TLS_TPOFF %s in %s --> %p",
157 obj->strtab + obj->symtab[symnum].st_name,
158 obj->path, (void *)*where));
159 break;
160
161 case R_TYPE(TLS_TPOFF32):
162 if (!defobj->tls_done &&
163 _rtld_tls_offset_allocate(obj))
164 return -1;
165
166 *where += (Elf_Addr)(defobj->tlsoffset - def->st_value);
167 rdbg(("TLS_TPOFF32 %s in %s --> %p",
168 obj->strtab + obj->symtab[symnum].st_name,
169 obj->path, (void *)*where));
170 break;
171
172 case R_TYPE(TLS_DTPMOD32):
173 *where = (Elf_Addr)(defobj->tlsindex);
174
175 rdbg(("TLS_DTPMOD32 %s in %s --> %p",
176 obj->strtab + obj->symtab[symnum].st_name,
177 obj->path, (void *)*where));
178 break;
179
180 case R_TYPE(TLS_DTPOFF32):
181 *where = (Elf_Addr)(def->st_value);
182
183 rdbg(("TLS_DTPOFF32 %s in %s --> %p",
184 obj->strtab + obj->symtab[symnum].st_name,
185 obj->path, (void *)*where));
186
187 break;
188
189 default:
190 rdbg(("sym = %lu, type = %lu, offset = %p, "
191 "contents = %p, symbol = %s",
192 (u_long)ELF_R_SYM(rel->r_info),
193 (u_long)ELF_R_TYPE(rel->r_info),
194 (void *)rel->r_offset, (void *)*where,
195 obj->strtab + obj->symtab[symnum].st_name));
196 _rtld_error("%s: Unsupported relocation type %ld "
197 "in non-PLT relocations",
198 obj->path, (u_long) ELF_R_TYPE(rel->r_info));
199 return -1;
200 }
201 }
202 return 0;
203}
204
205int
206_rtld_relocate_plt_lazy(Obj_Entry *obj)
207{
208 const Elf_Rel *rel;
209
210 for (rel = obj->pltrellim; rel-- > obj->pltrel; ) {
211 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
212
213 assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JMP_SLOT) ||
214 ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE));
215
216 if (ELF_R_TYPE(rel->r_info) == R_TYPE(IRELATIVE))
217 obj->ifunc_remaining = obj->pltrellim - rel;
218
219 /* Just relocate the GOT slots pointing into the PLT */
220 *where += (Elf_Addr)obj->relocbase;
221 rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
222 }
223
224 return 0;
225}
226
227static inline int
228_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel,
229 Elf_Addr *tp)
230{
231 Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
232 Elf_Addr target;
233 const Elf_Sym *def;
234 const Obj_Entry *defobj;
235 unsigned long info = rel->r_info;
236
237 if (ELF_R_TYPE(info) == R_TYPE(IRELATIVE))
238 return 0;
239
240 assert(ELF_R_TYPE(info) == R_TYPE(JMP_SLOT));
241
242 def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
243 if (__predict_false(def == NULL))
244 return -1;
245 if (__predict_false(def == &_rtld_sym_zero))
246 return 0;
247
248 if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
249 if (tp == NULL)
250 return 0;
251 target = _rtld_resolve_ifunc(defobj, def);
252 } else {
253 target = (Elf_Addr)(defobj->relocbase + def->st_value);
254 }
255
256 rdbg(("bind now/fixup in %s --> old=%p new=%p",
257 defobj->strtab + def->st_name, (void *)*where,
258 (void *)target));
259 if (*where != target)
260 *where = target;
261 if (tp)
262 *tp = target;
263 return 0;
264}
265
266caddr_t
267_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
268{
269 const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel
270 + reloff);
271 Elf_Addr new_value;
272 int err;
273
274 new_value = 0; /* XXX gcc */
275
276 _rtld_shared_enter();
277 err = _rtld_relocate_plt_object(obj, rel, &new_value);
278 if (err)
279 _rtld_die();
280 _rtld_shared_exit();
281
282 return (caddr_t)new_value;
283}
284
285int
286_rtld_relocate_plt_objects(const Obj_Entry *obj)
287{
288 const Elf_Rel *rel;
289 int err = 0;
290
291 for (rel = obj->pltrel; rel < obj->pltrellim; rel++) {
292 err = _rtld_relocate_plt_object(obj, rel, NULL);
293 if (err)
294 break;
295 }
296 return err;
297}
298
299/*
300 * i386 specific GNU variant of __tls_get_addr using register based
301 * argument passing.
302 */
303#define DTV_MAX_INDEX(dtv) ((size_t)((dtv)[-1]))
304
305__dso_public __attribute__((__regparm__(1))) void *
306___tls_get_addr(void *arg_)
307{
308 size_t *arg = (size_t *)arg_;
309 void **dtv;
310 struct tls_tcb *tcb = __lwp_getprivate_fast();
311 size_t idx = arg[0], offset = arg[1];
312
313 dtv = tcb->tcb_dtv;
314
315 if (__predict_true(idx < DTV_MAX_INDEX(dtv) && dtv[idx] != NULL))
316 return (uint8_t *)dtv[idx] + offset;
317
318 return _rtld_tls_get_addr(tcb, idx, offset);
319}
320