xref: /netbsd-src/sys/kern/exec_elf32.c (revision 93f9db1b75d415b78f73ed629beeb86235153473)
1 /*	$NetBSD: exec_elf32.c,v 1.39 1998/10/03 20:39:32 christos Exp $	*/
2 
3 /*-
4  * Copyright (c) 1994 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Christos Zoulas.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the NetBSD
21  *	Foundation, Inc. and its contributors.
22  * 4. Neither the name of The NetBSD Foundation nor the names of its
23  *    contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 /*
40  * Copyright (c) 1996 Christopher G. Demetriou
41  * All rights reserved.
42  *
43  * Redistribution and use in source and binary forms, with or without
44  * modification, are permitted provided that the following conditions
45  * are met:
46  * 1. Redistributions of source code must retain the above copyright
47  *    notice, this list of conditions and the following disclaimer.
48  * 2. Redistributions in binary form must reproduce the above copyright
49  *    notice, this list of conditions and the following disclaimer in the
50  *    documentation and/or other materials provided with the distribution.
51  * 3. The name of the author may not be used to endorse or promote products
52  *    derived from this software without specific prior written permission
53  *
54  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
55  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
56  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
57  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
58  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
59  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
60  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
61  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
62  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
63  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
64  */
65 
66 /* If not included by exec_elf64.c, ELFSIZE won't be defined. */
67 #ifndef ELFSIZE
68 #define	ELFSIZE		32
69 #endif
70 
71 #include "opt_compat_linux.h"
72 #include "opt_compat_ibcs2.h"
73 #include "opt_compat_svr4.h"
74 
75 #include <sys/param.h>
76 #include <sys/systm.h>
77 #include <sys/kernel.h>
78 #include <sys/proc.h>
79 #include <sys/malloc.h>
80 #include <sys/namei.h>
81 #include <sys/vnode.h>
82 #include <sys/exec.h>
83 #include <sys/exec_elf.h>
84 #include <sys/fcntl.h>
85 #include <sys/syscall.h>
86 #include <sys/signalvar.h>
87 #include <sys/mount.h>
88 #include <sys/stat.h>
89 
90 #include <sys/mman.h>
91 #include <vm/vm.h>
92 #include <vm/vm_param.h>
93 #include <vm/vm_map.h>
94 
95 #include <machine/cpu.h>
96 #include <machine/reg.h>
97 
98 #ifdef COMPAT_LINUX
99 #include <compat/linux/common/linux_exec.h>
100 #endif
101 
102 #ifdef COMPAT_SVR4
103 #include <compat/svr4/svr4_exec.h>
104 #endif
105 
106 #ifdef COMPAT_IBCS2
107 #include <compat/ibcs2/ibcs2_exec.h>
108 #endif
109 
110 int	ELFNAME(check_header) __P((Elf_Ehdr *, int));
111 int	ELFNAME(load_file) __P((struct proc *, struct exec_package *, char *,
112 	    struct exec_vmcmd_set *, u_long *, struct elf_args *, Elf_Addr *));
113 void	ELFNAME(load_psection) __P((struct exec_vmcmd_set *, struct vnode *,
114 	    Elf_Phdr *, Elf_Addr *, u_long *, int *));
115 
116 extern char sigcode[], esigcode[];
117 #ifdef SYSCALL_DEBUG
118 extern char *syscallnames[];
119 #endif
120 
121 struct emul ELFNAMEEND(emul_netbsd) = {
122 	"netbsd",
123 	NULL,
124 	sendsig,
125 	SYS_syscall,
126 	SYS_MAXSYSCALL,
127 	sysent,
128 #ifdef SYSCALL_DEBUG
129 	syscallnames,
130 #else
131 	NULL,
132 #endif
133 	ELF_AUX_ENTRIES * sizeof(AuxInfo),
134 	ELFNAME(copyargs),
135 	setregs,
136 	sigcode,
137 	esigcode,
138 };
139 
140 int (*ELFNAME(probe_funcs)[]) __P((struct proc *, struct exec_package *,
141     Elf_Ehdr *, char *, Elf_Addr *)) = {
142 #if defined(COMPAT_LINUX)
143 	ELFNAME2(linux,probe),
144 #endif
145 #if defined(COMPAT_SVR4) && (ELFSIZE == 32)
146 	ELFNAME2(svr4,probe),			/* XXX not 64-bit safe */
147 #endif
148 #if defined(COMPAT_IBCS2) && (ELFSIZE == 32)
149 	ELFNAME2(ibcs2,probe),			/* XXX not 64-bit safe */
150 #endif
151 };
152 
153 /* round up and down to page boundaries. */
154 #define	ELF_ROUND(a, b)		(((a) + (b) - 1) & ~((b) - 1))
155 #define	ELF_TRUNC(a, b)		((a) & ~((b) - 1))
156 
157 /*
158  * Copy arguments onto the stack in the normal way, but add some
159  * extra information in case of dynamic binding.
160  */
161 void *
162 ELFNAME(copyargs)(pack, arginfo, stack, argp)
163 	struct exec_package *pack;
164 	struct ps_strings *arginfo;
165 	void *stack;
166 	void *argp;
167 {
168 	size_t len;
169 	AuxInfo ai[ELF_AUX_ENTRIES], *a;
170 	struct elf_args *ap;
171 
172 	stack = copyargs(pack, arginfo, stack, argp);
173 	if (!stack)
174 		return NULL;
175 
176 	a = ai;
177 
178 	/*
179 	 * Push extra arguments on the stack needed by dynamically
180 	 * linked binaries
181 	 */
182 	if ((ap = (struct elf_args *)pack->ep_emul_arg)) {
183 
184 		a->au_id = AUX_phdr;
185 		a->au_v = ap->arg_phaddr;
186 		a++;
187 
188 		a->au_id = AUX_phent;
189 		a->au_v = ap->arg_phentsize;
190 		a++;
191 
192 		a->au_id = AUX_phnum;
193 		a->au_v = ap->arg_phnum;
194 		a++;
195 
196 		a->au_id = AUX_pagesz;
197 		a->au_v = NBPG;
198 		a++;
199 
200 		a->au_id = AUX_base;
201 		a->au_v = ap->arg_interp;
202 		a++;
203 
204 		a->au_id = AUX_flags;
205 		a->au_v = 0;
206 		a++;
207 
208 		a->au_id = AUX_entry;
209 		a->au_v = ap->arg_entry;
210 		a++;
211 
212 		free((char *)ap, M_TEMP);
213 		pack->ep_emul_arg = NULL;
214 	}
215 
216 	a->au_id = AUX_null;
217 	a->au_v = 0;
218 	a++;
219 
220 	len = (a - ai) * sizeof(AuxInfo);
221 	if (copyout(ai, stack, len))
222 		return NULL;
223 	(caddr_t)stack += len;
224 
225 	return stack;
226 }
227 
228 /*
229  * elf_check_header():
230  *
231  * Check header for validity; return 0 of ok ENOEXEC if error
232  */
233 int
234 ELFNAME(check_header)(eh, type)
235 	Elf_Ehdr *eh;
236 	int type;
237 {
238 
239 	if (memcmp(eh->e_ident, Elf_e_ident, Elf_e_siz) != 0)
240 		return ENOEXEC;
241 
242 	switch (eh->e_machine) {
243 
244 	ELFDEFNNAME(MACHDEP_ID_CASES)
245 
246 	default:
247 		return ENOEXEC;
248 	}
249 
250 	if (eh->e_type != type)
251 		return ENOEXEC;
252 
253 	return 0;
254 }
255 
256 /*
257  * elf_load_psection():
258  *
259  * Load a psection at the appropriate address
260  */
261 void
262 ELFNAME(load_psection)(vcset, vp, ph, addr, size, prot)
263 	struct exec_vmcmd_set *vcset;
264 	struct vnode *vp;
265 	Elf_Phdr *ph;
266 	Elf_Addr *addr;
267 	u_long *size;
268 	int *prot;
269 {
270 	u_long uaddr, msize, psize, rm, rf;
271 	long diff, offset;
272 
273 	/*
274 	 * If the user specified an address, then we load there.
275 	 */
276 	if (*addr != ELFDEFNNAME(NO_ADDR)) {
277 		if (ph->p_align > 1) {
278 			*addr = ELF_ROUND(*addr, ph->p_align);
279 			uaddr = ELF_TRUNC(ph->p_vaddr, ph->p_align);
280 		} else
281 			uaddr = ph->p_vaddr;
282 		diff = ph->p_vaddr - uaddr;
283 	} else {
284 		*addr = uaddr = ph->p_vaddr;
285 		if (ph->p_align > 1)
286 			*addr = ELF_TRUNC(uaddr, ph->p_align);
287 		diff = uaddr - *addr;
288 	}
289 
290 	*prot |= (ph->p_flags & Elf_pf_r) ? VM_PROT_READ : 0;
291 	*prot |= (ph->p_flags & Elf_pf_w) ? VM_PROT_WRITE : 0;
292 	*prot |= (ph->p_flags & Elf_pf_x) ? VM_PROT_EXECUTE : 0;
293 
294 	offset = ph->p_offset - diff;
295 	*size = ph->p_filesz + diff;
296 	msize = ph->p_memsz + diff;
297 	psize = round_page(*size);
298 
299 	if ((ph->p_flags & Elf_pf_w) != 0) {
300 		/*
301 		 * Because the pagedvn pager can't handle zero fill of the last
302 		 * data page if it's not page aligned we map the last page
303 		 * readvn.
304 		 */
305 		psize = trunc_page(*size);
306 		NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp,
307 		    offset, *prot);
308 		if(psize != *size)
309 			NEW_VMCMD(vcset, vmcmd_map_readvn, *size - psize,
310 			    *addr + psize, vp, offset + psize, *prot);
311 	} else
312 		NEW_VMCMD(vcset, vmcmd_map_pagedvn, psize, *addr, vp,
313 		    offset, *prot);
314 
315 	/*
316 	 * Check if we need to extend the size of the segment
317 	 */
318 	rm = round_page(*addr + msize);
319 	rf = round_page(*addr + *size);
320 
321 	if (rm != rf) {
322 		NEW_VMCMD(vcset, vmcmd_map_zero, rm - rf, rf, NULLVP,
323 		    0, *prot);
324 		*size = msize;
325 	}
326 }
327 
328 /*
329  * elf_read_from():
330  *
331  *	Read from vnode into buffer at offset.
332  */
333 int
334 ELFNAME(read_from)(p, vp, off, buf, size)
335 	struct vnode *vp;
336 	u_long off;
337 	struct proc *p;
338 	caddr_t buf;
339 	int size;
340 {
341 	int error;
342 	size_t resid;
343 
344 	if ((error = vn_rdwr(UIO_READ, vp, buf, size, off, UIO_SYSSPACE,
345 	    0, p->p_ucred, &resid, p)) != 0)
346 		return error;
347 	/*
348 	 * See if we got all of it
349 	 */
350 	if (resid != 0)
351 		return ENOEXEC;
352 	return 0;
353 }
354 
355 /*
356  * elf_load_file():
357  *
358  * Load a file (interpreter/library) pointed to by path
359  * [stolen from coff_load_shlib()]. Made slightly generic
360  * so it might be used externally.
361  */
362 int
363 ELFNAME(load_file)(p, epp, path, vcset, entry, ap, last)
364 	struct proc *p;
365 	struct exec_package *epp;
366 	char *path;
367 	struct exec_vmcmd_set *vcset;
368 	u_long *entry;
369 	struct elf_args	*ap;
370 	Elf_Addr *last;
371 {
372 	int error, i;
373 	struct nameidata nd;
374 	struct vnode *vp;
375 	struct vattr attr;
376 	Elf_Ehdr eh;
377 	Elf_Phdr *ph = NULL;
378 	u_long phsize;
379 	char *bp = NULL;
380 	Elf_Addr addr = *last;
381 
382 	bp = path;
383 	/*
384 	 * 1. open file
385 	 * 2. read filehdr
386 	 * 3. map text, data, and bss out of it using VM_*
387 	 */
388 	NDINIT(&nd, LOOKUP, FOLLOW | LOCKLEAF, UIO_SYSSPACE, path, p);
389 	if ((error = namei(&nd)) != 0)
390 		return error;
391 	vp = nd.ni_vp;
392 
393 	/*
394 	 * Similarly, if it's not marked as executable, or it's not a regular
395 	 * file, we don't allow it to be used.
396 	 */
397 	if (vp->v_type != VREG) {
398 		error = EACCES;
399 		goto badunlock;
400 	}
401 	if ((error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p)) != 0)
402 		goto badunlock;
403 
404 	/* get attributes */
405 	if ((error = VOP_GETATTR(vp, &attr, p->p_ucred, p)) != 0)
406 		goto badunlock;
407 
408 	/*
409 	 * Check mount point.  Though we're not trying to exec this binary,
410 	 * we will be executing code from it, so if the mount point
411 	 * disallows execution or set-id-ness, we punt or kill the set-id.
412 	 */
413 	if (vp->v_mount->mnt_flag & MNT_NOEXEC) {
414 		error = EACCES;
415 		goto badunlock;
416 	}
417 	if (vp->v_mount->mnt_flag & MNT_NOSUID)
418 		epp->ep_vap->va_mode &= ~(S_ISUID | S_ISGID);
419 
420 #ifdef notyet /* XXX cgd 960926 */
421 	XXX cgd 960926: (maybe) VOP_OPEN it (and VOP_CLOSE in copyargs?)
422 #endif
423 	VOP_UNLOCK(vp, 0);
424 
425 	if ((error = ELFNAME(read_from)(p, vp, 0, (caddr_t) &eh,
426 	    sizeof(eh))) != 0)
427 		goto bad;
428 
429 	if ((error = ELFNAME(check_header)(&eh, Elf_et_dyn)) != 0)
430 		goto bad;
431 
432 	phsize = eh.e_phnum * sizeof(Elf_Phdr);
433 	ph = (Elf_Phdr *)malloc(phsize, M_TEMP, M_WAITOK);
434 
435 	if ((error = ELFNAME(read_from)(p, vp, eh.e_phoff,
436 	    (caddr_t) ph, phsize)) != 0)
437 		goto bad;
438 
439 	/*
440 	 * Load all the necessary sections
441 	 */
442 	for (i = 0; i < eh.e_phnum; i++) {
443 		u_long size = 0;
444 		int prot = 0;
445 
446 		switch (ph[i].p_type) {
447 		case Elf_pt_load:
448 			ELFNAME(load_psection)(vcset, vp, &ph[i], &addr,
449 			    &size, &prot);
450 			/* If entry is within this section it must be text */
451 			if (eh.e_entry >= ph[i].p_vaddr &&
452 			    eh.e_entry < (ph[i].p_vaddr + size)) {
453 				/* XXX */
454 				*entry = addr + eh.e_entry;
455 #ifdef mips
456 				*entry -= ph[i].p_vaddr;
457 #endif
458 				ap->arg_interp = addr;
459 			}
460 			addr += size;
461 			break;
462 
463 		case Elf_pt_dynamic:
464 		case Elf_pt_phdr:
465 		case Elf_pt_note:
466 			break;
467 
468 		default:
469 			break;
470 		}
471 	}
472 
473 	free((char *)ph, M_TEMP);
474 	*last = addr;
475 	vrele(vp);
476 	return 0;
477 
478 badunlock:
479 	VOP_UNLOCK(vp, 0);
480 
481 bad:
482 	if (ph != NULL)
483 		free((char *)ph, M_TEMP);
484 #ifdef notyet /* XXX cgd 960926 */
485 	(maybe) VOP_CLOSE it
486 #endif
487 	vrele(vp);
488 	return error;
489 }
490 
491 /*
492  * exec_elf_makecmds(): Prepare an Elf binary's exec package
493  *
494  * First, set of the various offsets/lengths in the exec package.
495  *
496  * Then, mark the text image busy (so it can be demand paged) or error
497  * out if this is not possible.  Finally, set up vmcmds for the
498  * text, data, bss, and stack segments.
499  */
500 int
501 ELFNAME2(exec,makecmds)(p, epp)
502 	struct proc *p;
503 	struct exec_package *epp;
504 {
505 	Elf_Ehdr *eh = epp->ep_hdr;
506 	Elf_Phdr *ph, *pp;
507 	Elf_Addr phdr = 0, pos = 0;
508 	int error, i, n, nload;
509 	char interp[MAXPATHLEN];
510 	u_long phsize;
511 
512 	if (epp->ep_hdrvalid < sizeof(Elf_Ehdr))
513 		return ENOEXEC;
514 
515 	if (ELFNAME(check_header)(eh, Elf_et_exec))
516 		return ENOEXEC;
517 
518 	/*
519 	 * check if vnode is in open for writing, because we want to
520 	 * demand-page out of it.  if it is, don't do it, for various
521 	 * reasons
522 	 */
523 	if (epp->ep_vp->v_writecount != 0) {
524 #ifdef DIAGNOSTIC
525 		if (epp->ep_vp->v_flag & VTEXT)
526 			panic("exec: a VTEXT vnode has writecount != 0\n");
527 #endif
528 		return ETXTBSY;
529 	}
530 	/*
531 	 * Allocate space to hold all the program headers, and read them
532 	 * from the file
533 	 */
534 	phsize = eh->e_phnum * sizeof(Elf_Phdr);
535 	ph = (Elf_Phdr *)malloc(phsize, M_TEMP, M_WAITOK);
536 
537 	if ((error = ELFNAME(read_from)(p, epp->ep_vp, eh->e_phoff,
538 	    (caddr_t) ph, phsize)) != 0)
539 		goto bad;
540 
541 	epp->ep_taddr = epp->ep_tsize = ELFDEFNNAME(NO_ADDR);
542 	epp->ep_daddr = epp->ep_dsize = ELFDEFNNAME(NO_ADDR);
543 
544 	interp[0] = '\0';
545 
546 	for (i = 0; i < eh->e_phnum; i++) {
547 		pp = &ph[i];
548 		if (pp->p_type == Elf_pt_interp) {
549 			if (pp->p_filesz >= sizeof(interp))
550 				goto bad;
551 			if ((error = ELFNAME(read_from)(p, epp->ep_vp,
552 			    pp->p_offset, (caddr_t) interp,
553 			    pp->p_filesz)) != 0)
554 				goto bad;
555 			break;
556 		}
557 	}
558 
559 	/*
560 	 * Setup things for native emulation.
561 	 */
562 	epp->ep_emul = &ELFNAMEEND(emul_netbsd);
563 	pos = ELFDEFNNAME(NO_ADDR);
564 
565 	/*
566 	 * On the same architecture, we may be emulating different systems.
567 	 * See which one will accept this executable. This currently only
568 	 * applies to SVR4, and IBCS2 on the i386 and Linux on the i386
569 	 * and the Alpha.
570 	 *
571 	 * Probe functions would normally see if the interpreter (if any)
572 	 * exists. Emulation packages may possibly replace the interpreter in
573 	 * interp[] with a changed path (/emul/xxx/<path>), and also
574 	 * set the ep_emul field in the exec package structure.
575 	 */
576 	n = sizeof(ELFNAME(probe_funcs)) / sizeof(ELFNAME(probe_funcs)[0]);
577 	if (n != 0) {
578 		error = ENOEXEC;
579 		for (i = 0; i < n && error; i++)
580 			error = ELFNAME(probe_funcs)[i](p, epp, eh,
581 			    interp, &pos);
582 #ifdef notyet
583 		/*
584 		 * We should really use a signature in our native binaries
585 		 * and have our own probe function for matching binaries,
586 		 * before trying the emulations. For now, if the emulation
587 		 * probes failed we default to native.
588 		 */
589 		if (error)
590 			goto bad;
591 #endif
592 	}
593 
594 	/*
595 	 * Load all the necessary sections
596 	 */
597 	for (i = nload = 0; i < eh->e_phnum; i++) {
598 		Elf_Addr  addr = ELFDEFNNAME(NO_ADDR);
599 		u_long size = 0;
600 		int prot = 0;
601 
602 		pp = &ph[i];
603 
604 		switch (ph[i].p_type) {
605 		case Elf_pt_load:
606 			/*
607 			 * XXX
608 			 * Can handle only 2 sections: text and data
609 			 */
610 			if (nload++ == 2)
611 				goto bad;
612 			ELFNAME(load_psection)(&epp->ep_vmcmds, epp->ep_vp,
613 			    &ph[i], &addr, &size, &prot);
614 
615 			/*
616 			 * Decide whether it's text or data by looking
617 			 * at the entry point.
618 			 */
619 			if (eh->e_entry >= addr &&
620 			    eh->e_entry < (addr + size)) {
621 				epp->ep_taddr = addr;
622 				epp->ep_tsize = size;
623 				if (epp->ep_daddr == ELFDEFNNAME(NO_ADDR)) {
624 					epp->ep_daddr = addr;
625 					epp->ep_dsize = size;
626 				}
627 			} else {
628 				epp->ep_daddr = addr;
629 				epp->ep_dsize = size;
630 			}
631 			break;
632 
633 		case Elf_pt_shlib:
634 #ifndef COMPAT_IBCS2			/* SCO has these sections */
635 			error = ENOEXEC;
636 			goto bad;
637 #endif
638 
639 		case Elf_pt_interp:
640 			/* Already did this one */
641 		case Elf_pt_dynamic:
642 		case Elf_pt_note:
643 			break;
644 
645 		case Elf_pt_phdr:
646 			/* Note address of program headers (in text segment) */
647 			phdr = pp->p_vaddr;
648 			break;
649 
650 		default:
651 			/*
652 			 * Not fatal; we don't need to understand everything.
653 			 */
654 			break;
655 		}
656 	}
657 
658 	/* this breaks on, e.g., OpenBSD-compatible mips shared binaries. */
659 #ifndef ELF_INTERP_NON_RELOCATABLE
660 	/*
661 	 * If no position to load the interpreter was set by a probe
662 	 * function, pick the same address that a non-fixed mmap(0, ..)
663 	 * would (i.e. something safely out of the way).
664 	 */
665 	if (pos == ELFDEFNNAME(NO_ADDR))
666 		pos = round_page(epp->ep_daddr + MAXDSIZ);
667 #endif	/* !ELF_INTERP_NON_RELOCATABLE */
668 
669 	/*
670 	 * Check if we found a dynamically linked binary and arrange to load
671 	 * it's interpreter
672 	 */
673 	if (interp[0]) {
674 		struct elf_args *ap;
675 
676 		ap = (struct elf_args *)malloc(sizeof(struct elf_args),
677 		    M_TEMP, M_WAITOK);
678 		if ((error = ELFNAME(load_file)(p, epp, interp,
679 		    &epp->ep_vmcmds, &epp->ep_entry, ap, &pos)) != 0) {
680 			free((char *)ap, M_TEMP);
681 			goto bad;
682 		}
683 		pos += phsize;
684 		ap->arg_phaddr = phdr;
685 
686 		ap->arg_phentsize = eh->e_phentsize;
687 		ap->arg_phnum = eh->e_phnum;
688 		ap->arg_entry = eh->e_entry;
689 
690 		epp->ep_emul_arg = ap;
691 	} else
692 		epp->ep_entry = eh->e_entry;
693 
694 #ifdef ELF_MAP_PAGE_ZERO
695 	/* Dell SVR4 maps page zero, yeuch! */
696 	NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_readvn, NBPG, 0, epp->ep_vp, 0,
697 	    VM_PROT_READ);
698 #endif
699 	free((char *)ph, M_TEMP);
700 	epp->ep_vp->v_flag |= VTEXT;
701 	return exec_elf_setup_stack(p, epp);
702 
703 bad:
704 	free((char *)ph, M_TEMP);
705 	kill_vmcmds(&epp->ep_vmcmds);
706 	return ENOEXEC;
707 }
708