1/*	$NetBSD: mdreloc.c,v 1.36 2011/04/12 16:40:04 matt Exp $	*/
2
3#include <sys/cdefs.h>
4#ifndef lint
5__RCSID("$NetBSD: mdreloc.c,v 1.36 2011/04/12 16:40:04 matt Exp $");
6#endif /* not lint */
7
8#include <sys/types.h>
9#include <string.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	rellim = (const Elf_Rel *)((const uint8_t *)rel + relsz);
43	for (; rel < rellim; rel++) {
44		where = (Elf_Addr *)(relocbase + rel->r_offset);
45		*where += (Elf_Addr)relocbase;
46	}
47}
48
49/*
50 * It is possible for the compiler to emit relocations for unaligned data.
51 * We handle this situation with these inlines.
52 */
53#define	RELOC_ALIGNED_P(x) \
54	(((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)
55
56static inline Elf_Addr
57load_ptr(void *where)
58{
59	Elf_Addr res;
60
61	memcpy(&res, where, sizeof(res));
62
63	return (res);
64}
65
66static inline void
67store_ptr(void *where, Elf_Addr val)
68{
69
70	memcpy(where, &val, sizeof(val));
71}
72
73int
74_rtld_relocate_nonplt_objects(Obj_Entry *obj)
75{
76	const Elf_Rel *rel;
77
78	for (rel = obj->rel; rel < obj->rellim; rel++) {
79		Elf_Addr        *where;
80		const Elf_Sym   *def;
81		const Obj_Entry *defobj;
82		Elf_Addr         tmp;
83		unsigned long	 symnum;
84
85		where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
86		symnum = ELF_R_SYM(rel->r_info);
87
88		switch (ELF_R_TYPE(rel->r_info)) {
89		case R_TYPE(NONE):
90			break;
91
92#if 1 /* XXX should not occur */
93		case R_TYPE(PC24): {	/* word32 S - P + A */
94			Elf32_Sword addend;
95
96			/*
97			 * Extract addend and sign-extend if needed.
98			 */
99			addend = *where;
100			if (addend & 0x00800000)
101				addend |= 0xff000000;
102
103			def = _rtld_find_symdef(symnum, obj, &defobj, false);
104			if (def == NULL)
105				return -1;
106			tmp = (Elf_Addr)obj->relocbase + def->st_value
107			    - (Elf_Addr)where + (addend << 2);
108			if ((tmp & 0xfe000000) != 0xfe000000 &&
109			    (tmp & 0xfe000000) != 0) {
110				_rtld_error(
111				"%s: R_ARM_PC24 relocation @ %p to %s failed "
112				"(displacement %ld (%#lx) out of range)",
113				    obj->path, where,
114				    obj->strtab + obj->symtab[symnum].st_name,
115				    (long) tmp, (long) tmp);
116				return -1;
117			}
118			tmp >>= 2;
119			*where = (*where & 0xff000000) | (tmp & 0x00ffffff);
120			rdbg(("PC24 %s in %s --> %p @ %p in %s",
121			    obj->strtab + obj->symtab[symnum].st_name,
122			    obj->path, (void *)*where, where, defobj->path));
123			break;
124		}
125#endif
126
127		case R_TYPE(ABS32):	/* word32 B + S + A */
128		case R_TYPE(GLOB_DAT):	/* word32 B + S */
129			def = _rtld_find_symdef(symnum, obj, &defobj, false);
130			if (def == NULL)
131				return -1;
132			if (__predict_true(RELOC_ALIGNED_P(where))) {
133				tmp = *where + (Elf_Addr)defobj->relocbase +
134				    def->st_value;
135				/* Set the Thumb bit, if needed.  */
136				if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC)
137				    tmp |= 1;
138				*where = tmp;
139			} else {
140				tmp = load_ptr(where) +
141				    (Elf_Addr)defobj->relocbase +
142				    def->st_value;
143				/* Set the Thumb bit, if needed.  */
144				if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC)
145				    tmp |= 1;
146				store_ptr(where, tmp);
147			}
148			rdbg(("ABS32/GLOB_DAT %s in %s --> %p @ %p in %s",
149			    obj->strtab + obj->symtab[symnum].st_name,
150			    obj->path, (void *)tmp, where, defobj->path));
151			break;
152
153		case R_TYPE(RELATIVE):	/* word32 B + A */
154			if (__predict_true(RELOC_ALIGNED_P(where))) {
155				tmp = *where + (Elf_Addr)obj->relocbase;
156				*where = tmp;
157			} else {
158				tmp = load_ptr(where) +
159				    (Elf_Addr)obj->relocbase;
160				store_ptr(where, tmp);
161			}
162			rdbg(("RELATIVE in %s --> %p", obj->path,
163			    (void *)tmp));
164			break;
165
166		case R_TYPE(COPY):
167			/*
168			 * These are deferred until all other relocations have
169			 * been done.  All we do here is make sure that the
170			 * COPY relocation is not in a shared library.  They
171			 * are allowed only in executable files.
172			 */
173			if (obj->isdynamic) {
174				_rtld_error(
175			"%s: Unexpected R_COPY relocation in shared library",
176				    obj->path);
177				return -1;
178			}
179			rdbg(("COPY (avoid in main)"));
180			break;
181
182		case R_TYPE(TLS_DTPOFF32):
183			def = _rtld_find_symdef(symnum, obj, &defobj, false);
184			if (def == NULL)
185				return -1;
186
187			tmp = (Elf_Addr)(def->st_value);
188			if (__predict_true(RELOC_ALIGNED_P(where)))
189				*where = tmp;
190			else
191				store_ptr(where, tmp);
192
193			rdbg(("TLS_DTPOFF32 %s in %s --> %p",
194			    obj->strtab + obj->symtab[symnum].st_name,
195			    obj->path, (void *)tmp));
196
197			break;
198		case R_TYPE(TLS_DTPMOD32):
199			def = _rtld_find_symdef(symnum, obj, &defobj, false);
200			if (def == NULL)
201				return -1;
202
203			tmp = (Elf_Addr)(defobj->tlsindex);
204			if (__predict_true(RELOC_ALIGNED_P(where)))
205				*where = tmp;
206			else
207				store_ptr(where, tmp);
208
209			rdbg(("TLS_DTPMOD32 %s in %s --> %p",
210			    obj->strtab + obj->symtab[symnum].st_name,
211			    obj->path, (void *)tmp));
212
213			break;
214
215		case R_TYPE(TLS_TPOFF32):
216			def = _rtld_find_symdef(symnum, obj, &defobj, false);
217			if (def == NULL)
218				return -1;
219
220			if (!defobj->tls_done &&
221			    _rtld_tls_offset_allocate(obj))
222				return -1;
223
224			tmp = (Elf_Addr)def->st_value + defobj->tlsoffset +
225			    sizeof(struct tls_tcb);
226			if (__predict_true(RELOC_ALIGNED_P(where)))
227				*where = tmp;
228			else
229				store_ptr(where, tmp);
230			rdbg(("TLS_TPOFF32 %s in %s --> %p",
231			    obj->strtab + obj->symtab[symnum].st_name,
232			    obj->path, (void *)tmp));
233			break;
234
235		default:
236			rdbg(("sym = %lu, type = %lu, offset = %p, "
237			    "contents = %p, symbol = %s",
238			    symnum, (u_long)ELF_R_TYPE(rel->r_info),
239			    (void *)rel->r_offset, (void *)load_ptr(where),
240			    obj->strtab + obj->symtab[symnum].st_name));
241			_rtld_error("%s: Unsupported relocation type %ld "
242			    "in non-PLT relocations",
243			    obj->path, (u_long) ELF_R_TYPE(rel->r_info));
244			return -1;
245		}
246	}
247	return 0;
248}
249
250int
251_rtld_relocate_plt_lazy(const Obj_Entry *obj)
252{
253	const Elf_Rel *rel;
254
255	if (!obj->relocbase)
256		return 0;
257
258	for (rel = obj->pltrel; rel < obj->pltrellim; rel++) {
259		Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
260
261		assert(ELF_R_TYPE(rel->r_info) == R_TYPE(JUMP_SLOT));
262
263		/* Just relocate the GOT slots pointing into the PLT */
264		*where += (Elf_Addr)obj->relocbase;
265		rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
266	}
267
268	return 0;
269}
270
271static int
272_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rel *rel,
273	Elf_Addr *tp)
274{
275	Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rel->r_offset);
276	Elf_Addr new_value;
277	const Elf_Sym  *def;
278	const Obj_Entry *defobj;
279	unsigned long info = rel->r_info;
280
281	assert(ELF_R_TYPE(info) == R_TYPE(JUMP_SLOT));
282
283	def = _rtld_find_plt_symdef(ELF_R_SYM(info), obj, &defobj, tp != NULL);
284	if (__predict_false(def == NULL))
285		return -1;
286	if (__predict_false(def == &_rtld_sym_zero))
287		return 0;
288
289	new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
290	/* Set the Thumb bit, if needed.  */
291	if (ELF_ST_TYPE(def->st_info) == STT_ARM_TFUNC)
292		new_value |= 1;
293	rdbg(("bind now/fixup in %s --> old=%p new=%p",
294	    defobj->strtab + def->st_name, (void *)*where, (void *)new_value));
295	if (*where != new_value)
296		*where = new_value;
297	if (tp)
298		*tp = new_value;
299
300	return 0;
301}
302
303caddr_t
304_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
305{
306	const Elf_Rel *rel = (const Elf_Rel *)((const uint8_t *)obj->pltrel + reloff);
307	Elf_Addr new_value = 0;	/* XXX gcc */
308	int err;
309
310	_rtld_shared_enter();
311	err = _rtld_relocate_plt_object(obj, rel, &new_value);
312	if (err)
313		_rtld_die();
314	_rtld_shared_exit();
315
316	return (caddr_t)new_value;
317}
318int
319_rtld_relocate_plt_objects(const Obj_Entry *obj)
320{
321	const Elf_Rel *rel;
322	int err = 0;
323
324	for (rel = obj->pltrel; rel < obj->pltrellim; rel++) {
325		err = _rtld_relocate_plt_object(obj, rel, NULL);
326		if (err)
327			break;
328	}
329
330	return err;
331}
332