xref: /titanic_41/usr/src/lib/libproc/common/Psymtab_machelf32.c (revision 8d4e547db823a866b8f73efc0acdc423e2963caf)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 
22 /*
23  * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #pragma ident	"%Z%%M%	%I%	%E% SMI"
28 
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <stddef.h>
32 #include <memory.h>
33 #include <sys/sysmacros.h>
34 #include <sys/machelf.h>
35 
36 #include "Pcontrol.h"
37 #include "Psymtab_machelf.h"
38 
39 
40 /*
41  * This file contains code for use by Psymtab.c that is compiled once
42  * for each supported ELFCLASS.
43  *
44  * When processing ELF files, it is common to encounter a situation where
45  * a program with one ELFCLASS (32 or 64-bit) is required to examine a
46  * file with a different ELFCLASS. For example, the 32-bit linker (ld) may
47  * be used to link a 64-bit program. The simplest solution to this problem
48  * is to duplicate each such piece of code, modifying only the data types,
49  * and to use if statements to select the code to run. The problem with
50  * doing it that way is that the resulting code is difficult to maintain.
51  * It is inevitable that the copies will not always get modified identically,
52  * and will drift apart. The only robust solution is to generate the
53  * multiple instances of code automatically from a single piece of code.
54  *
55  * The solution used within the Solaris linker is to write the code once,
56  * using the data types defined in sys/machelf.h, and then to compile that
57  * code twice, once with _ELF64 defined (to generate ELFCLASS64 code) and
58  * once without (to generate ELFCLASS32). We use the same approach here.
59  *
60  * Note that the _ELF64 definition does not refer to the ELFCLASS of
61  * the resulting code, but rather, to the ELFCLASS of the data it
62  * examines. By repeating the above double-compilation for both 32-bit
63  * and 64-bit builds, we end up with 4 instances, which collectively
64  * can handle any combination of program and ELF data class:
65  *
66  *		    \  Compilation class
67  *		     \	  32	64
68  *		      \------------------
69  *		       |
70  *		    32 |   X	 X
71  *   ELF Data Class    |
72  *		    64 |   X	 X
73  */
74 
75 
76 
77 /*
78  * Read data from the specified process and construct an in memory
79  * image of an ELF file that will let us use libelf for most of the
80  * work we need to later (e.g. symbol table lookups). This is used
81  * in cases where no usable on-disk image for the process is available.
82  * We need sections for the dynsym, dynstr, and plt, and we need
83  * the program headers from the text section. The former is used in
84  * Pbuild_file_symtab(); the latter is used in several functions in
85  * Pcore.c to reconstruct the origin of each mapping from the load
86  * object that spawned it.
87  *
88  * Here are some useful pieces of elf trivia that will help
89  * to elucidate this code.
90  *
91  * All the information we need about the dynstr can be found in these
92  * two entries in the dynamic section:
93  *
94  *	DT_STRTAB	base of dynstr
95  *	DT_STRSZ	size of dynstr
96  *
97  * So deciphering the dynstr is pretty straightforward.
98  *
99  * The dynsym is a little trickier.
100  *
101  *	DT_SYMTAB	base of dynsym
102  *	DT_SYMENT	size of a dynstr entry (Elf{32,64}_Sym)
103  *	DT_HASH		base of hash table for dynamic lookups
104  *
105  * The DT_SYMTAB entry gives us any easy way of getting to the base
106  * of the dynsym, but getting the size involves rooting around in the
107  * dynamic lookup hash table. Here's the layout of the hash table:
108  *
109  *		+-------------------+
110  *		|	nbucket	    |	All values are 32-bit
111  *		+-------------------+	(Elf32_Word or Elf64_Word)
112  *		|	nchain	    |
113  *		+-------------------+
114  *		|	bucket[0]   |
115  *		|	. . .	    |
116  *		| bucket[nbucket-1] |
117  *		+-------------------+
118  *		|	chain[0]    |
119  *		|	. . .	    |
120  *		|  chain[nchain-1]  |
121  *		+-------------------+
122  *	(figure 5-12 from the SYS V Generic ABI)
123  *
124  * Symbols names are hashed into a particular bucket which contains
125  * an index into the symbol table. Each entry in the symbol table
126  * has a corresponding entry in the chain table which tells the
127  * consumer where the next entry in the hash chain is. We can use
128  * the nchain field to find out the size of the dynsym.
129  *
130  * If there is a dynsym present, there may also be an optional
131  * section called the SUNW_ldynsym that augments the dynsym by
132  * providing local function symbols. When the Solaris linker lays
133  * out a file that has both of these sections, it makes sure that
134  * the data for the two sections is adjacent with the SUNW_ldynsym
135  * in front. This allows the runtime linker to treat these two
136  * symbol tables as being a single larger table. There are two
137  * items in the dynamic section for this:
138  *
139  *	DT_SUNW_SYMTAB	base of the SUNW_ldynsym
140  *	DT_SUNW_SYMSZ	total size of SUNW_ldynsym and dynsym
141  *			added together. We can figure out the
142  *			size of the SUNW_ldynsym section by
143  *			subtracting the size of the dynsym
144  *			(described above) from this value.
145  *
146  * We can figure out the size of the .plt section, but it takes some
147  * doing. We need to use the following information:
148  *
149  *	DT_PLTGOT	base of the PLT
150  *	DT_JMPREL	base of the PLT's relocation section
151  *	DT_PLTRELSZ	size of the PLT's relocation section
152  *	DT_PLTREL	type of the PLT's relocation section
153  *
154  * We can use the relocation section to figure out the address of the
155  * last entry and subtract off the value of DT_PLTGOT to calculate
156  * the size of the PLT.
157  *
158  * For more information, check out the System V Generic ABI.
159  */
160 
161 
162 /*
163  * The fake_elfXX() function generated by this file uses the following
164  * string as the string table for the section names. Since it is critical
165  * to count correctly, and to improve readability, the SHSTR_NDX_ macros
166  * supply the proper offset for each name within the string.
167  */
168 static char shstr[] =
169 	".shstrtab\0.dynsym\0.dynstr\0.dynamic\0.plt\0.SUNW_ldynsym";
170 
171 /* Offsets within shstr for each name */
172 #define	SHSTR_NDX_shstrtab	0
173 #define	SHSTR_NDX_dynsym	10
174 #define	SHSTR_NDX_dynstr	18
175 #define	SHSTR_NDX_dynamic	26
176 #define	SHSTR_NDX_plt		35
177 #define	SHSTR_NDX_SUNW_ldynsym	40
178 
179 
180 /*
181  * Section header alignment for 32 and 64-bit ELF files differs
182  */
183 #ifdef _ELF64
184 #define	SH_ADDRALIGN	8
185 #else
186 #define	SH_ADDRALIGN	4
187 #endif
188 
189 /*
190  * This is the smallest number of PLT relocation entries allowed in a proper
191  * .plt section.
192  */
193 #ifdef	__sparc
194 #define	PLTREL_MIN_ENTRIES	4	/* SPARC psABI 3.0 and SCD 2.4 */
195 #else
196 #ifdef	__lint
197 /*
198  * On x86, lint would complain about unsigned comparison with
199  * PLTREL_MIN_ENTRIES. This define fakes up the value of PLTREL_MIN_ENTRIES
200  * and silences lint. On SPARC, there is no such issue.
201  */
202 #define	PLTREL_MIN_ENTRIES	1
203 #else
204 #define	PLTREL_MIN_ENTRIES	0
205 #endif
206 #endif
207 
208 #ifdef _ELF64
209 Elf *
210 fake_elf64(struct ps_prochandle *P, file_info_t *fptr, uintptr_t addr,
211     Ehdr *ehdr, uint_t phnum, Phdr *phdr)
212 #else
213 Elf *
214 fake_elf32(struct ps_prochandle *P, file_info_t *fptr, uintptr_t addr,
215     Ehdr *ehdr, uint_t phnum, Phdr *phdr)
216 #endif
217 {
218 	enum {
219 		DI_PLTGOT,
220 		DI_JMPREL,
221 		DI_PLTRELSZ,
222 		DI_PLTREL,
223 		DI_SYMTAB,
224 		DI_HASH,
225 		DI_SYMENT,
226 		DI_STRTAB,
227 		DI_STRSZ,
228 		DI_SUNW_SYMTAB,
229 		DI_SUNW_SYMSZ,
230 		DI_NENT
231 	};
232 	/*
233 	 * Mask of dynamic options that must be present in a well
234 	 * formed dynamic section. We need all of these in order to
235 	 * put together a complete set of elf sections. They are
236 	 * mandatory in both executables and shared objects so if one
237 	 * of them is missing, we're in some trouble and should abort.
238 	 * The PLT items are expected, but we will let them slide if
239 	 * need be. The DI_SUNW_SYM* items are completely optional, so
240 	 * we use them if they are present and ignore them otherwise.
241 	 */
242 	const int di_req_mask = (1 << DI_SYMTAB) | (1 << DI_HASH) |
243 		(1 << DI_SYMENT) | (1 << DI_STRTAB) | (1 << DI_STRSZ);
244 	int di_mask = 0;
245 	size_t size = 0;
246 	caddr_t elfdata = NULL;
247 	Elf *elf;
248 	size_t dynsym_size, ldynsym_size;
249 	int dynstr_shndx;
250 	Ehdr *ep;
251 	Shdr *sp;
252 	Dyn *dp;
253 	Dyn *d[DI_NENT] = { 0 };
254 	uint_t i;
255 	Off off;
256 	size_t pltsz = 0, pltentsz;
257 
258 
259 	if (ehdr->e_type == ET_DYN)
260 		phdr->p_vaddr += addr;
261 
262 	if ((dp = malloc(phdr->p_filesz)) == NULL)
263 		goto bad;
264 
265 	if (Pread(P, dp, phdr->p_filesz, phdr->p_vaddr) != phdr->p_filesz)
266 		goto bad;
267 
268 #ifndef _ELF64
269 	/*
270 	 * Allow librtld_db the opportunity to "fix" the program
271 	 * headers, if it needs to, before we process them.
272 	 */
273 	if (P->rap != NULL && ehdr->e_type == ET_DYN) {
274 		rd_fix_phdrs(P->rap, dp, phdr->p_filesz, addr);
275 	}
276 #endif
277 
278 	/*
279 	 * Iterate over the items in the dynamic section, grabbing
280 	 * the address of items we want and saving them in dp[].
281 	 */
282 	for (i = 0; i < phdr->p_filesz / sizeof (Dyn); i++) {
283 		switch (dp[i].d_tag) {
284 		/* For the .plt section */
285 		case DT_PLTGOT:
286 			d[DI_PLTGOT] = &dp[i];
287 			break;
288 		case DT_JMPREL:
289 			d[DI_JMPREL] = &dp[i];
290 			break;
291 		case DT_PLTRELSZ:
292 			d[DI_PLTRELSZ] = &dp[i];
293 			break;
294 		case DT_PLTREL:
295 			d[DI_PLTREL] = &dp[i];
296 			break;
297 
298 		/* For the .dynsym section */
299 		case DT_SYMTAB:
300 			d[DI_SYMTAB] = &dp[i];
301 			di_mask |= (1 << DI_SYMTAB);
302 			break;
303 		case DT_HASH:
304 			d[DI_HASH] = &dp[i];
305 			di_mask |= (1 << DI_HASH);
306 			break;
307 		case DT_SYMENT:
308 			d[DI_SYMENT] = &dp[i];
309 			di_mask |= (1 << DI_SYMENT);
310 			break;
311 		case DT_SUNW_SYMTAB:
312 			d[DI_SUNW_SYMTAB] = &dp[i];
313 			break;
314 		case DT_SUNW_SYMSZ:
315 			d[DI_SUNW_SYMSZ] = &dp[i];
316 			break;
317 
318 		/* For the .dynstr section */
319 		case DT_STRTAB:
320 			d[DI_STRTAB] = &dp[i];
321 			di_mask |= (1 << DI_STRTAB);
322 			break;
323 		case DT_STRSZ:
324 			d[DI_STRSZ] = &dp[i];
325 			di_mask |= (1 << DI_STRSZ);
326 			break;
327 		}
328 	}
329 
330 	/* Ensure all required entries were collected */
331 	if ((di_mask & di_req_mask) != di_req_mask) {
332 		dprintf("text section missing required dynamic entries\n");
333 		goto bad;
334 	}
335 
336 	if (ehdr->e_type == ET_DYN) {
337 		if (d[DI_PLTGOT] != NULL)
338 			d[DI_PLTGOT]->d_un.d_ptr += addr;
339 		if (d[DI_JMPREL] != NULL)
340 			d[DI_JMPREL]->d_un.d_ptr += addr;
341 		d[DI_SYMTAB]->d_un.d_ptr += addr;
342 		d[DI_HASH]->d_un.d_ptr += addr;
343 		d[DI_STRTAB]->d_un.d_ptr += addr;
344 		if (d[DI_SUNW_SYMTAB] != NULL)
345 			d[DI_SUNW_SYMTAB]->d_un.d_ptr += addr;
346 	}
347 
348 	/* SUNW_ldynsym must be adjacent to dynsym. Ignore if not */
349 	if ((d[DI_SUNW_SYMTAB] != NULL) && (d[DI_SUNW_SYMSZ] != NULL) &&
350 	    ((d[DI_SYMTAB]->d_un.d_ptr <= d[DI_SUNW_SYMTAB]->d_un.d_ptr) ||
351 	    (d[DI_SYMTAB]->d_un.d_ptr >= (d[DI_SUNW_SYMTAB]->d_un.d_ptr +
352 	    d[DI_SUNW_SYMSZ]->d_un.d_val)))) {
353 		d[DI_SUNW_SYMTAB] = NULL;
354 		d[DI_SUNW_SYMSZ] = NULL;
355 	}
356 
357 	/* elf header */
358 	size = sizeof (Ehdr);
359 
360 	/* program headers from in-core elf fragment */
361 	size += phnum * ehdr->e_phentsize;
362 
363 	/* unused shdr, and .shstrtab section */
364 	size += sizeof (Shdr);
365 	size += sizeof (Shdr);
366 	size += roundup(sizeof (shstr), SH_ADDRALIGN);
367 
368 	/*
369 	 * .dynsym and .SUNW_ldynsym sections.
370 	 *
371 	 * The string table section used for the symbol table and
372 	 * dynamic sections lies immediately after the dynsym, so the
373 	 * presence of SUNW_ldynsym changes the dynstr section index.
374 	 */
375 	if (d[DI_SUNW_SYMTAB] != NULL) {
376 		size += sizeof (Shdr);	/* SUNW_ldynsym shdr */
377 		ldynsym_size = (size_t)d[DI_SUNW_SYMSZ]->d_un.d_val;
378 		dynsym_size = ldynsym_size - (d[DI_SYMTAB]->d_un.d_ptr
379 		    - d[DI_SUNW_SYMTAB]->d_un.d_ptr);
380 		ldynsym_size -= dynsym_size;
381 		dynstr_shndx = 4;
382 	} else {
383 		Word nchain;
384 
385 		if (Pread(P, &nchain, sizeof (nchain),
386 		    d[DI_HASH]->d_un.d_ptr + sizeof (nchain)) !=
387 		    sizeof (nchain)) {
388 			dprintf("Pread of .dynsym at %lx failed\n",
389 			    (long)(d[DI_HASH]->d_un.d_val + sizeof (nchain)));
390 			goto bad;
391 		}
392 		dynsym_size = sizeof (Sym) * nchain;
393 		ldynsym_size = 0;
394 		dynstr_shndx = 3;
395 	}
396 	size += sizeof (Shdr) + ldynsym_size + dynsym_size;
397 
398 	/* .dynstr section */
399 	size += sizeof (Shdr);
400 	size += roundup(d[DI_STRSZ]->d_un.d_val, SH_ADDRALIGN);
401 
402 	/* .dynamic section */
403 	size += sizeof (Shdr);
404 	size += roundup(phdr->p_filesz, SH_ADDRALIGN);
405 
406 	/* .plt section */
407 	if (d[DI_PLTGOT] != NULL && d[DI_JMPREL] != NULL &&
408 	    d[DI_PLTRELSZ] != NULL && d[DI_PLTREL] != NULL) {
409 		uintptr_t penult, ult;
410 		uintptr_t jmprel = d[DI_JMPREL]->d_un.d_ptr;
411 		size_t pltrelsz = d[DI_PLTRELSZ]->d_un.d_val;
412 
413 		if (d[DI_PLTREL]->d_un.d_val == DT_RELA) {
414 			uint_t entries = pltrelsz / sizeof (Rela);
415 			Rela r[2];
416 
417 			if (entries < PLTREL_MIN_ENTRIES) {
418 				dprintf("too few PLT relocation entries "
419 				    "(found %d, expected at least %d)\n",
420 				    entries, PLTREL_MIN_ENTRIES);
421 				goto bad;
422 			}
423 			if (entries < PLTREL_MIN_ENTRIES + 2)
424 				goto done_with_plt;
425 
426 			if (Pread(P, r, sizeof (r), jmprel + sizeof (r[0]) *
427 			    entries - sizeof (r)) != sizeof (r)) {
428 				dprintf("Pread of DT_RELA failed\n");
429 				goto bad;
430 			}
431 
432 			penult = r[0].r_offset;
433 			ult = r[1].r_offset;
434 
435 		} else if (d[DI_PLTREL]->d_un.d_val == DT_REL) {
436 			uint_t entries = pltrelsz / sizeof (Rel);
437 			Rel r[2];
438 
439 			if (entries < PLTREL_MIN_ENTRIES) {
440 				dprintf("too few PLT relocation entries "
441 				    "(found %d, expected at least %d)\n",
442 				    entries, PLTREL_MIN_ENTRIES);
443 				goto bad;
444 			}
445 			if (entries < PLTREL_MIN_ENTRIES + 2)
446 				goto done_with_plt;
447 
448 			if (Pread(P, r, sizeof (r), jmprel + sizeof (r[0]) *
449 			    entries - sizeof (r)) != sizeof (r)) {
450 				dprintf("Pread of DT_REL failed\n");
451 				goto bad;
452 			}
453 
454 			penult = r[0].r_offset;
455 			ult = r[1].r_offset;
456 		} else {
457 			dprintf(".plt: unknown jmprel value\n");
458 			goto bad;
459 		}
460 
461 		pltentsz = ult - penult;
462 
463 		if (ehdr->e_type == ET_DYN)
464 			ult += addr;
465 
466 		pltsz = ult - d[DI_PLTGOT]->d_un.d_ptr + pltentsz;
467 
468 		size += sizeof (Shdr);
469 		size += roundup(pltsz, SH_ADDRALIGN);
470 	}
471 done_with_plt:
472 
473 	if ((elfdata = calloc(1, size)) == NULL)
474 		goto bad;
475 
476 	/* LINTED - alignment */
477 	ep = (Ehdr *)elfdata;
478 	(void) memcpy(ep, ehdr, offsetof(Ehdr, e_phoff));
479 
480 	ep->e_ehsize = sizeof (Ehdr);
481 	ep->e_phoff = sizeof (Ehdr);
482 	ep->e_phentsize = ehdr->e_phentsize;
483 	ep->e_phnum = phnum;
484 	ep->e_shoff = ep->e_phoff + phnum * ep->e_phentsize;
485 	ep->e_shentsize = sizeof (Shdr);
486 	/*
487 	 * Plt and SUNW_ldynsym sections are optional. C logical
488 	 * binary operators return a 0 or 1 value, so the following
489 	 * adds 1 for each optional section present.
490 	 */
491 	ep->e_shnum = 5 + (pltsz != 0) + (d[DI_SUNW_SYMTAB] != NULL);
492 	ep->e_shstrndx = 1;
493 
494 	/* LINTED - alignment */
495 	sp = (Shdr *)(elfdata + ep->e_shoff);
496 	off = ep->e_shoff + ep->e_shentsize * ep->e_shnum;
497 
498 	/*
499 	 * Copying the program headers directly from the process's
500 	 * address space is a little suspect, but since we only
501 	 * use them for their address and size values, this is fine.
502 	 */
503 	if (Pread(P, &elfdata[ep->e_phoff], phnum * ep->e_phentsize,
504 	    addr + ehdr->e_phoff) != phnum * ep->e_phentsize) {
505 		dprintf("failed to read program headers\n");
506 		goto bad;
507 	}
508 
509 	/*
510 	 * The first elf section is always skipped.
511 	 */
512 	sp++;
513 
514 	/*
515 	 * Section Header: .shstrtab
516 	 */
517 	sp->sh_name = SHSTR_NDX_shstrtab;
518 	sp->sh_type = SHT_STRTAB;
519 	sp->sh_flags = SHF_STRINGS;
520 	sp->sh_addr = 0;
521 	sp->sh_offset = off;
522 	sp->sh_size = sizeof (shstr);
523 	sp->sh_link = 0;
524 	sp->sh_info = 0;
525 	sp->sh_addralign = 1;
526 	sp->sh_entsize = 0;
527 
528 	(void) memcpy(&elfdata[off], shstr, sizeof (shstr));
529 	off += roundup(sp->sh_size, SH_ADDRALIGN);
530 	sp++;
531 
532 	/*
533 	 * Section Header: .SUNW_ldynsym
534 	 */
535 	if (d[DI_SUNW_SYMTAB] != NULL) {
536 		sp->sh_name = SHSTR_NDX_SUNW_ldynsym;
537 		sp->sh_type = SHT_SUNW_LDYNSYM;
538 		sp->sh_flags = SHF_ALLOC;
539 		sp->sh_addr = d[DI_SUNW_SYMTAB]->d_un.d_ptr;
540 		if (ehdr->e_type == ET_DYN)
541 			sp->sh_addr -= addr;
542 		sp->sh_offset = off;
543 		sp->sh_size = ldynsym_size;
544 		sp->sh_link = dynstr_shndx;
545 		/* Index of 1st global in table that has none == # items */
546 		sp->sh_info = sp->sh_size / sizeof (Sym);
547 		sp->sh_addralign = SH_ADDRALIGN;
548 		sp->sh_entsize = sizeof (Sym);
549 
550 		if (Pread(P, &elfdata[off], sp->sh_size,
551 		    d[DI_SUNW_SYMTAB]->d_un.d_ptr) != sp->sh_size) {
552 			dprintf("failed to read .SUNW_ldynsym at %lx\n",
553 			    (long)d[DI_SUNW_SYMTAB]->d_un.d_ptr);
554 			goto bad;
555 		}
556 		off += sp->sh_size;
557 		/* No need to round up ldynsym data. Dynsym data is same type */
558 		sp++;
559 	}
560 
561 	/*
562 	 * Section Header: .dynsym
563 	 */
564 	sp->sh_name = SHSTR_NDX_dynsym;
565 	sp->sh_type = SHT_DYNSYM;
566 	sp->sh_flags = SHF_ALLOC;
567 	sp->sh_addr = d[DI_SYMTAB]->d_un.d_ptr;
568 	if (ehdr->e_type == ET_DYN)
569 		sp->sh_addr -= addr;
570 	sp->sh_offset = off;
571 	sp->sh_size = dynsym_size;
572 	sp->sh_link = dynstr_shndx;
573 	sp->sh_info = 1;	/* Index of 1st global in table */
574 	sp->sh_addralign = SH_ADDRALIGN;
575 	sp->sh_entsize = sizeof (Sym);
576 
577 	if (Pread(P, &elfdata[off], sp->sh_size,
578 	    d[DI_SYMTAB]->d_un.d_ptr) != sp->sh_size) {
579 		dprintf("failed to read .dynsym at %lx\n",
580 		    (long)d[DI_SYMTAB]->d_un.d_ptr);
581 		goto bad;
582 	}
583 
584 	off += roundup(sp->sh_size, SH_ADDRALIGN);
585 	sp++;
586 
587 	/*
588 	 * Section Header: .dynstr
589 	 */
590 	sp->sh_name = SHSTR_NDX_dynstr;
591 	sp->sh_type = SHT_STRTAB;
592 	sp->sh_flags = SHF_ALLOC | SHF_STRINGS;
593 	sp->sh_addr = d[DI_STRTAB]->d_un.d_ptr;
594 	if (ehdr->e_type == ET_DYN)
595 		sp->sh_addr -= addr;
596 	sp->sh_offset = off;
597 	sp->sh_size = d[DI_STRSZ]->d_un.d_val;
598 	sp->sh_link = 0;
599 	sp->sh_info = 0;
600 	sp->sh_addralign = 1;
601 	sp->sh_entsize = 0;
602 
603 	if (Pread(P, &elfdata[off], sp->sh_size,
604 	    d[DI_STRTAB]->d_un.d_ptr) != sp->sh_size) {
605 		dprintf("failed to read .dynstr\n");
606 		goto bad;
607 	}
608 	off += roundup(sp->sh_size, SH_ADDRALIGN);
609 	sp++;
610 
611 	/*
612 	 * Section Header: .dynamic
613 	 */
614 	sp->sh_name = SHSTR_NDX_dynamic;
615 	sp->sh_type = SHT_DYNAMIC;
616 	sp->sh_flags = SHF_WRITE | SHF_ALLOC;
617 	sp->sh_addr = phdr->p_vaddr;
618 	if (ehdr->e_type == ET_DYN)
619 		sp->sh_addr -= addr;
620 	sp->sh_offset = off;
621 	sp->sh_size = phdr->p_filesz;
622 	sp->sh_link = dynstr_shndx;
623 	sp->sh_info = 0;
624 	sp->sh_addralign = SH_ADDRALIGN;
625 	sp->sh_entsize = sizeof (Dyn);
626 
627 	(void) memcpy(&elfdata[off], dp, sp->sh_size);
628 	off += roundup(sp->sh_size, SH_ADDRALIGN);
629 	sp++;
630 
631 	/*
632 	 * Section Header: .plt
633 	 */
634 	if (pltsz != 0) {
635 		sp->sh_name = SHSTR_NDX_plt;
636 		sp->sh_type = SHT_PROGBITS;
637 		sp->sh_flags = SHF_WRITE | SHF_ALLOC | SHF_EXECINSTR;
638 		sp->sh_addr = d[DI_PLTGOT]->d_un.d_ptr;
639 		if (ehdr->e_type == ET_DYN)
640 			sp->sh_addr -= addr;
641 		sp->sh_offset = off;
642 		sp->sh_size = pltsz;
643 		sp->sh_link = 0;
644 		sp->sh_info = 0;
645 		sp->sh_addralign = SH_ADDRALIGN;
646 		sp->sh_entsize = pltentsz;
647 
648 		if (Pread(P, &elfdata[off], sp->sh_size,
649 		    d[DI_PLTGOT]->d_un.d_ptr) != sp->sh_size) {
650 			dprintf("failed to read .plt\n");
651 			goto bad;
652 		}
653 		off += roundup(sp->sh_size, SH_ADDRALIGN);
654 		sp++;
655 	}
656 
657 	free(dp);
658 	if ((elf = elf_memory(elfdata, size)) == NULL) {
659 		free(elfdata);
660 		return (NULL);
661 	}
662 
663 	fptr->file_elfmem = elfdata;
664 
665 	return (elf);
666 
667 bad:
668 	if (dp != NULL)
669 		free(dp);
670 	if (elfdata != NULL)
671 		free(elfdata);
672 	return (NULL);
673 
674 
675 }
676