8828 udapl: value computed is not used

[unleashed.git] / usr / src / lib / libproc / common / Psymtab_machelf32.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2015, Joyent, Inc. All rights reserved.
 */

#include <assert.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <memory.h>
#include <sys/sysmacros.h>
#include <sys/machelf.h>

#include "Pcontrol.h"
#include "Psymtab_machelf.h"


/*
 * This file contains code for use by Psymtab.c that is compiled once
 * for each supported ELFCLASS.
 *
 * When processing ELF files, it is common to encounter a situation where
 * a program with one ELFCLASS (32 or 64-bit) is required to examine a
 * file with a different ELFCLASS. For example, the 32-bit linker (ld) may
 * be used to link a 64-bit program. The simplest solution to this problem
 * is to duplicate each such piece of code, modifying only the data types,
 * and to use if statements to select the code to run. The problem with
 * doing it that way is that the resulting code is difficult to maintain.
 * It is inevitable that the copies will not always get modified identically,
 * and will drift apart. The only robust solution is to generate the
 * multiple instances of code automatically from a single piece of code.
 *
 * The solution used within the Solaris linker is to write the code once,
 * using the data types defined in sys/machelf.h, and then to compile that
 * code twice, once with _ELF64 defined (to generate ELFCLASS64 code) and
 * once without (to generate ELFCLASS32). We use the same approach here.
 *
 * Note that the _ELF64 definition does not refer to the ELFCLASS of
 * the resulting code, but rather, to the ELFCLASS of the data it
 * examines. By repeating the above double-compilation for both 32-bit
 * and 64-bit builds, we end up with 4 instances, which collectively
 * can handle any combination of program and ELF data class:
 *
 *                  \  Compilation class
 *                   \    32    64
 *                    \------------------
 *                     |
 *                  32 |   X     X
 *   ELF Data Class    |
 *                  64 |   X     X
 */



/*
 * Read data from the specified process and construct an in memory
 * image of an ELF file that will let us use libelf for most of the
 * work we need to later (e.g. symbol table lookups). This is used
 * in cases where no usable on-disk image for the process is available.
 * We need sections for the dynsym, dynstr, and plt, and we need
 * the program headers from the text section. The former is used in
 * Pbuild_file_symtab(); the latter is used in several functions in
 * Pcore.c to reconstruct the origin of each mapping from the load
 * object that spawned it.
 *
 * Here are some useful pieces of elf trivia that will help
 * to elucidate this code.
 *
 * All the information we need about the dynstr can be found in these
 * two entries in the dynamic section:
 *
 *      DT_STRTAB       base of dynstr
 *      DT_STRSZ        size of dynstr
 *
 * So deciphering the dynstr is pretty straightforward.
 *
 * The dynsym is a little trickier.
 *
 *      DT_SYMTAB       base of dynsym
 *      DT_SYMENT       size of a dynstr entry (Elf{32,64}_Sym)
 *      DT_HASH         base of hash table for dynamic lookups
 *
 * The DT_SYMTAB entry gives us any easy way of getting to the base
 * of the dynsym, but getting the size involves rooting around in the
 * dynamic lookup hash table. Here's the layout of the hash table:
 *
 *              +-------------------+
 *              |       nbucket     |   All values are 32-bit
 *              +-------------------+   (Elf32_Word or Elf64_Word)
 *              |       nchain      |
 *              +-------------------+
 *              |       bucket[0]   |
 *              |       . . .       |
 *              | bucket[nbucket-1] |
 *              +-------------------+
 *              |       chain[0]    |
 *              |       . . .       |
 *              |  chain[nchain-1]  |
 *              +-------------------+
 *      (figure 5-12 from the SYS V Generic ABI)
 *
 * Symbols names are hashed into a particular bucket which contains
 * an index into the symbol table. Each entry in the symbol table
 * has a corresponding entry in the chain table which tells the
 * consumer where the next entry in the hash chain is. We can use
 * the nchain field to find out the size of the dynsym.
 *
 * If there is a dynsym present, there may also be an optional
 * section called the SUNW_ldynsym that augments the dynsym by
 * providing local function symbols. When the Solaris linker lays
 * out a file that has both of these sections, it makes sure that
 * the data for the two sections is adjacent with the SUNW_ldynsym
 * in front. This allows the runtime linker to treat these two
 * symbol tables as being a single larger table. There are two
 * items in the dynamic section for this:
 *
 *      DT_SUNW_SYMTAB  base of the SUNW_ldynsym
 *      DT_SUNW_SYMSZ   total size of SUNW_ldynsym and dynsym
 *                      added together. We can figure out the
 *                      size of the SUNW_ldynsym section by
 *                      subtracting the size of the dynsym
 *                      (described above) from this value.
 *
 * We can figure out the size of the .plt section, but it takes some
 * doing. We need to use the following information:
 *
 *      DT_PLTGOT       GOT PLT entry offset (on x86) or PLT offset (on sparc)
 *      DT_JMPREL       base of the PLT's relocation section
 *      DT_PLTRELSZ     size of the PLT's relocation section
 *      DT_PLTREL       type of the PLT's relocation section
 *
 * We can use the number of relocation entries to calculate the size of
 * the PLT.  We get the address of the PLT by looking up the
 * _PROCEDURE_LINKAGE_TABLE_ symbol.
 *
 * For more information, check out the System V Generic ABI.
 */


/*
 * The fake_elfXX() function generated by this file uses the following
 * string as the string table for the section names. Since it is critical
 * to count correctly, and to improve readability, the SHSTR_NDX_ macros
 * supply the proper offset for each name within the string.
 */
static char shstr[] =
        ".shstrtab\0.dynsym\0.dynstr\0.dynamic\0.plt\0.SUNW_ldynsym";

/* Offsets within shstr for each name */
#define SHSTR_NDX_shstrtab      0
#define SHSTR_NDX_dynsym        10
#define SHSTR_NDX_dynstr        18
#define SHSTR_NDX_dynamic       26
#define SHSTR_NDX_plt           35
#define SHSTR_NDX_SUNW_ldynsym  40


/*
 * Section header alignment for 32 and 64-bit ELF files differs
 */
#ifdef _ELF64
#define SH_ADDRALIGN    8
#else
#define SH_ADDRALIGN    4
#endif

/*
 * This is the smallest number of PLT relocation entries allowed in a proper
 * .plt section.
 */
#ifdef  __sparc
#define PLTREL_MIN_ENTRIES      4       /* SPARC psABI 3.0 and SCD 2.4 */
#else
#ifdef  __lint
/*
 * On x86, lint would complain about unsigned comparison with
 * PLTREL_MIN_ENTRIES. This define fakes up the value of PLTREL_MIN_ENTRIES
 * and silences lint. On SPARC, there is no such issue.
 */
#define PLTREL_MIN_ENTRIES      1
#else
#define PLTREL_MIN_ENTRIES      0
#endif
#endif

#ifdef _ELF64
Elf *
fake_elf64(struct ps_prochandle *P, file_info_t *fptr, uintptr_t addr,
    Ehdr *ehdr, uint_t phnum, Phdr *phdr)
#else
Elf *
fake_elf32(struct ps_prochandle *P, file_info_t *fptr, uintptr_t addr,
    Ehdr *ehdr, uint_t phnum, Phdr *phdr)
#endif
{
        enum {
                DI_PLTGOT,
                DI_JMPREL,
                DI_PLTRELSZ,
                DI_PLTREL,
                DI_SYMTAB,
                DI_HASH,
                DI_SYMENT,
                DI_STRTAB,
                DI_STRSZ,
                DI_SUNW_SYMTAB,
                DI_SUNW_SYMSZ,
                DI_NENT
        };
        /*
         * Mask of dynamic options that must be present in a well
         * formed dynamic section. We need all of these in order to
         * put together a complete set of elf sections. They are
         * mandatory in both executables and shared objects so if one
         * of them is missing, we're in some trouble and should abort.
         * The PLT items are expected, but we will let them slide if
         * need be. The DI_SUNW_SYM* items are completely optional, so
         * we use them if they are present and ignore them otherwise.
         */
        const int di_req_mask = (1 << DI_SYMTAB) |
                (1 << DI_SYMENT) | (1 << DI_STRTAB) | (1 << DI_STRSZ);
        int di_mask = 0;
        size_t size = 0;
        caddr_t elfdata = NULL;
        Elf *elf;
        size_t dynsym_size = 0, ldynsym_size;
        int dynstr_shndx;
        Ehdr *ep;
        Shdr *sp;
        Dyn *dp = NULL;
        Dyn *d[DI_NENT] = { 0 };
        uint_t i;
        Off off;
        size_t pltsz = 0, pltentries = 0;
        uintptr_t hptr = NULL;
        Word hnchains = 0, hnbuckets = 0;

        if (ehdr->e_type == ET_DYN)
                phdr->p_vaddr += addr;

        if (P->rap != NULL) {
                if (rd_get_dyns(P->rap, addr, (void **)&dp, NULL) != RD_OK)
                        goto bad;
        } else {
                if ((dp = malloc(phdr->p_filesz)) == NULL)
                        goto bad;
                if (Pread(P, dp, phdr->p_filesz, phdr->p_vaddr) !=
                    phdr->p_filesz)
                        goto bad;
        }

        /*
         * Iterate over the items in the dynamic section, grabbing
         * the address of items we want and saving them in dp[].
         */
        for (i = 0; i < phdr->p_filesz / sizeof (Dyn); i++) {
                switch (dp[i].d_tag) {
                /* For the .plt section */
                case DT_PLTGOT:
                        d[DI_PLTGOT] = &dp[i];
                        break;
                case DT_JMPREL:
                        d[DI_JMPREL] = &dp[i];
                        break;
                case DT_PLTRELSZ:
                        d[DI_PLTRELSZ] = &dp[i];
                        break;
                case DT_PLTREL:
                        d[DI_PLTREL] = &dp[i];
                        break;

                /* For the .dynsym section */
                case DT_SYMTAB:
                        d[DI_SYMTAB] = &dp[i];
                        di_mask |= (1 << DI_SYMTAB);
                        break;
                case DT_HASH:
                        d[DI_HASH] = &dp[i];
                        di_mask |= (1 << DI_HASH);
                        break;
                case DT_SYMENT:
                        d[DI_SYMENT] = &dp[i];
                        di_mask |= (1 << DI_SYMENT);
                        break;
                case DT_SUNW_SYMTAB:
                        d[DI_SUNW_SYMTAB] = &dp[i];
                        break;
                case DT_SUNW_SYMSZ:
                        d[DI_SUNW_SYMSZ] = &dp[i];
                        break;

                /* For the .dynstr section */
                case DT_STRTAB:
                        d[DI_STRTAB] = &dp[i];
                        di_mask |= (1 << DI_STRTAB);
                        break;
                case DT_STRSZ:
                        d[DI_STRSZ] = &dp[i];
                        di_mask |= (1 << DI_STRSZ);
                        break;
                }
        }

        /* Ensure all required entries were collected */
        if ((di_mask & di_req_mask) != di_req_mask) {
                dprintf("text section missing required dynamic entries: "
                    "required 0x%x, found 0x%x\n", di_req_mask, di_mask);
                goto bad;
        }

        /* SUNW_ldynsym must be adjacent to dynsym. Ignore if not */
        if ((d[DI_SUNW_SYMTAB] != NULL) && (d[DI_SUNW_SYMSZ] != NULL) &&
            ((d[DI_SYMTAB]->d_un.d_ptr <= d[DI_SUNW_SYMTAB]->d_un.d_ptr) ||
            (d[DI_SYMTAB]->d_un.d_ptr >= (d[DI_SUNW_SYMTAB]->d_un.d_ptr +
            d[DI_SUNW_SYMSZ]->d_un.d_val)))) {
                d[DI_SUNW_SYMTAB] = NULL;
                d[DI_SUNW_SYMSZ] = NULL;
        }

        /* elf header */
        size = sizeof (Ehdr);

        /* program headers from in-core elf fragment */
        size += phnum * ehdr->e_phentsize;

        /* unused shdr, and .shstrtab section */
        size += sizeof (Shdr);
        size += sizeof (Shdr);
        size += roundup(sizeof (shstr), SH_ADDRALIGN);

        if (d[DI_HASH] != NULL) {
                Word hash[2];

                hptr = d[DI_HASH]->d_un.d_ptr;
                if (ehdr->e_type == ET_DYN)
                        hptr += addr;

                if (Pread(P, hash, sizeof (hash), hptr) != sizeof (hash)) {
                        dprintf("Pread of .hash at %lx failed\n",
                            (long)(hptr));
                        goto bad;
                }

                hnbuckets = hash[0];
                hnchains = hash[1];
        }

        /*
         * .dynsym and .SUNW_ldynsym sections.
         *
         * The string table section used for the symbol table and
         * dynamic sections lies immediately after the dynsym, so the
         * presence of SUNW_ldynsym changes the dynstr section index.
         */
        if (d[DI_SUNW_SYMTAB] != NULL) {
                size += sizeof (Shdr);  /* SUNW_ldynsym shdr */
                ldynsym_size = (size_t)d[DI_SUNW_SYMSZ]->d_un.d_val;
                dynsym_size = ldynsym_size - (d[DI_SYMTAB]->d_un.d_ptr
                    - d[DI_SUNW_SYMTAB]->d_un.d_ptr);
                ldynsym_size -= dynsym_size;
                dynstr_shndx = 4;
        } else {
                dynsym_size = sizeof (Sym) * hnchains;
                ldynsym_size = 0;
                dynstr_shndx = 3;
        }
        size += sizeof (Shdr) + ldynsym_size + dynsym_size;

        /* .dynstr section */
        size += sizeof (Shdr);
        size += roundup(d[DI_STRSZ]->d_un.d_val, SH_ADDRALIGN);

        /* .dynamic section */
        size += sizeof (Shdr);
        size += roundup(phdr->p_filesz, SH_ADDRALIGN);

        /* .plt section */
        if (d[DI_PLTGOT] != NULL && d[DI_JMPREL] != NULL &&
            d[DI_PLTRELSZ] != NULL && d[DI_PLTREL] != NULL) {
                size_t pltrelsz = d[DI_PLTRELSZ]->d_un.d_val;

                if (d[DI_PLTREL]->d_un.d_val == DT_RELA) {
                        pltentries = pltrelsz / sizeof (Rela);
                } else if (d[DI_PLTREL]->d_un.d_val == DT_REL) {
                        pltentries = pltrelsz / sizeof (Rel);
                } else {
                        /* fall back to the platform default */
#if ((defined(__i386) || defined(__amd64)) && !defined(_ELF64))
                        pltentries = pltrelsz / sizeof (Rel);
                        dprintf("DI_PLTREL not found, defaulting to Rel");
#else /* (!(__i386 || __amd64)) || _ELF64 */
                        pltentries = pltrelsz / sizeof (Rela);
                        dprintf("DI_PLTREL not found, defaulting to Rela");
#endif /* (!(__i386 || __amd64) || _ELF64 */
                }

                if (pltentries < PLTREL_MIN_ENTRIES) {
                        dprintf("too few PLT relocation entries "
                            "(found %lu, expected at least %d)\n",
                            (long)pltentries, PLTREL_MIN_ENTRIES);
                        goto bad;
                }
                if (pltentries < PLTREL_MIN_ENTRIES + 2)
                        goto done_with_plt;

                /*
                 * Now that we know the number of plt relocation entries
                 * we can calculate the size of the plt.
                 */
                pltsz = (pltentries + M_PLT_XNumber) * M_PLT_ENTSIZE;
#if defined(__sparc)
                /* The sparc PLT always has a (delay slot) nop at the end */
                pltsz += 4;
#endif /* __sparc */

                size += sizeof (Shdr);
                size += roundup(pltsz, SH_ADDRALIGN);
        }
done_with_plt:

        if ((elfdata = calloc(1, size)) == NULL) {
                dprintf("failed to allocate size %ld\n", (long)size);
                goto bad;
        }

        /* LINTED - alignment */
        ep = (Ehdr *)elfdata;
        (void) memcpy(ep, ehdr, offsetof(Ehdr, e_phoff));

        ep->e_ehsize = sizeof (Ehdr);
        ep->e_phoff = sizeof (Ehdr);
        ep->e_phentsize = ehdr->e_phentsize;
        ep->e_phnum = phnum;
        ep->e_shoff = ep->e_phoff + phnum * ep->e_phentsize;
        ep->e_shentsize = sizeof (Shdr);
        /*
         * Plt and SUNW_ldynsym sections are optional. C logical
         * binary operators return a 0 or 1 value, so the following
         * adds 1 for each optional section present.
         */
        ep->e_shnum = 5 + (pltsz != 0) + (d[DI_SUNW_SYMTAB] != NULL);
        ep->e_shstrndx = 1;

        /* LINTED - alignment */
        sp = (Shdr *)(elfdata + ep->e_shoff);
        off = ep->e_shoff + ep->e_shentsize * ep->e_shnum;

        /*
         * Copying the program headers directly from the process's
         * address space is a little suspect, but since we only
         * use them for their address and size values, this is fine.
         */
        if (Pread(P, &elfdata[ep->e_phoff], phnum * ep->e_phentsize,
            addr + ehdr->e_phoff) != phnum * ep->e_phentsize) {
                dprintf("failed to read program headers\n");
                goto bad;
        }

        /*
         * The first elf section is always skipped.
         */
        sp++;

        /*
         * Section Header: .shstrtab
         */
        sp->sh_name = SHSTR_NDX_shstrtab;
        sp->sh_type = SHT_STRTAB;
        sp->sh_flags = SHF_STRINGS;
        sp->sh_addr = 0;
        sp->sh_offset = off;
        sp->sh_size = sizeof (shstr);
        sp->sh_link = 0;
        sp->sh_info = 0;
        sp->sh_addralign = 1;
        sp->sh_entsize = 0;

        (void) memcpy(&elfdata[off], shstr, sizeof (shstr));
        off += roundup(sp->sh_size, SH_ADDRALIGN);
        sp++;

        /*
         * Section Header: .SUNW_ldynsym
         */
        if (d[DI_SUNW_SYMTAB] != NULL) {
                sp->sh_name = SHSTR_NDX_SUNW_ldynsym;
                sp->sh_type = SHT_SUNW_LDYNSYM;
                sp->sh_flags = SHF_ALLOC;
                sp->sh_addr = d[DI_SUNW_SYMTAB]->d_un.d_ptr;
                if (ehdr->e_type == ET_DYN)
                        sp->sh_addr += addr;
                sp->sh_offset = off;
                sp->sh_size = ldynsym_size;
                sp->sh_link = dynstr_shndx;
                /* Index of 1st global in table that has none == # items */
                sp->sh_info = sp->sh_size / sizeof (Sym);
                sp->sh_addralign = SH_ADDRALIGN;
                sp->sh_entsize = sizeof (Sym);

                if (Pread(P, &elfdata[off], sp->sh_size,
                    sp->sh_addr) != sp->sh_size) {
                        dprintf("failed to read .SUNW_ldynsym at %lx\n",
                            (long)sp->sh_addr);
                        goto bad;
                }
                off += sp->sh_size;
                /* No need to round up ldynsym data. Dynsym data is same type */
                sp++;
        }

        /*
         * Section Header: .dynsym
         */
        sp->sh_name = SHSTR_NDX_dynsym;
        sp->sh_type = SHT_DYNSYM;
        sp->sh_flags = SHF_ALLOC;
        sp->sh_addr = d[DI_SYMTAB]->d_un.d_ptr;
        if (ehdr->e_type == ET_DYN)
                sp->sh_addr += addr;
        sp->sh_offset = off;
        sp->sh_size = dynsym_size;
        sp->sh_link = dynstr_shndx;
        sp->sh_info = 1;        /* Index of 1st global in table */
        sp->sh_addralign = SH_ADDRALIGN;
        sp->sh_entsize = sizeof (Sym);

        if (Pread(P, &elfdata[off], sp->sh_size,
            sp->sh_addr) != sp->sh_size) {
                dprintf("failed to read .dynsym at %lx\n",
                    (long)sp->sh_addr);
                goto bad;
        }

        off += roundup(sp->sh_size, SH_ADDRALIGN);
        sp++;

        /*
         * Section Header: .dynstr
         */
        sp->sh_name = SHSTR_NDX_dynstr;
        sp->sh_type = SHT_STRTAB;
        sp->sh_flags = SHF_ALLOC | SHF_STRINGS;
        sp->sh_addr = d[DI_STRTAB]->d_un.d_ptr;
        if (ehdr->e_type == ET_DYN)
                sp->sh_addr += addr;
        sp->sh_offset = off;
        sp->sh_size = d[DI_STRSZ]->d_un.d_val;
        sp->sh_link = 0;
        sp->sh_info = 0;
        sp->sh_addralign = 1;
        sp->sh_entsize = 0;

        if (Pread(P, &elfdata[off], sp->sh_size,
            sp->sh_addr) != sp->sh_size) {
                dprintf("failed to read .dynstr\n");
                goto bad;
        }
        off += roundup(sp->sh_size, SH_ADDRALIGN);
        sp++;

        /*
         * Section Header: .dynamic
         */
        sp->sh_name = SHSTR_NDX_dynamic;
        sp->sh_type = SHT_DYNAMIC;
        sp->sh_flags = SHF_WRITE | SHF_ALLOC;
        sp->sh_addr = phdr->p_vaddr;
        if (ehdr->e_type == ET_DYN)
                sp->sh_addr -= addr;
        sp->sh_offset = off;
        sp->sh_size = phdr->p_filesz;
        sp->sh_link = dynstr_shndx;
        sp->sh_info = 0;
        sp->sh_addralign = SH_ADDRALIGN;
        sp->sh_entsize = sizeof (Dyn);

        (void) memcpy(&elfdata[off], dp, sp->sh_size);
        off += roundup(sp->sh_size, SH_ADDRALIGN);
        sp++;

        /*
         * Section Header: .plt
         */
        if (pltsz != 0) {
                ulong_t         plt_symhash;
                uint_t          htmp, ndx;
                uintptr_t       strtabptr, strtabname;
                Sym             sym, *symtabptr;
                uint_t          *hash;
                char            strbuf[sizeof ("_PROCEDURE_LINKAGE_TABLE_")];

                /*
                 * Now we need to find the address of the plt by looking
                 * up the "_PROCEDURE_LINKAGE_TABLE_" symbol.
                 */

                /* get the address of the symtab and strtab sections */
                strtabptr = d[DI_STRTAB]->d_un.d_ptr;
                symtabptr = (Sym *)(uintptr_t)d[DI_SYMTAB]->d_un.d_ptr;
                if (ehdr->e_type == ET_DYN) {
                        strtabptr += addr;
                        symtabptr = (Sym*)((uintptr_t)symtabptr + addr);
                }

                if ((hptr == NULL) || (hnbuckets == 0) || (hnchains == 0)) {
                        dprintf("empty or missing .hash\n");
                        goto badplt;
                }

                /* find the .hash bucket address for this symbol */
                plt_symhash = elf_hash("_PROCEDURE_LINKAGE_TABLE_");
                htmp = plt_symhash % hnbuckets;
                hash = &((uint_t *)hptr)[2 + htmp];

                /* read the elf hash bucket index */
                if (Pread(P, &ndx, sizeof (ndx), (uintptr_t)hash) !=
                    sizeof (ndx)) {
                        dprintf("Pread of .hash at %lx failed\n", (long)hash);
                        goto badplt;
                }

                while (ndx) {
                        if (Pread(P, &sym, sizeof (sym),
                            (uintptr_t)&symtabptr[ndx]) != sizeof (sym)) {
                                dprintf("Pread of .symtab at %lx failed\n",
                                    (long)&symtabptr[ndx]);
                                goto badplt;
                        }

                        strtabname = strtabptr + sym.st_name;
                        if (Pread_string(P, strbuf, sizeof (strbuf),
                            strtabname) < 0) {
                                dprintf("Pread of .strtab at %lx failed\n",
                                    (long)strtabname);
                                goto badplt;
                        }

                        if (strcmp("_PROCEDURE_LINKAGE_TABLE_", strbuf) == 0)
                                break;

                        hash = &((uint_t *)hptr)[2 + hnbuckets + ndx];
                        if (Pread(P, &ndx, sizeof (ndx), (uintptr_t)hash) !=
                            sizeof (ndx)) {
                                dprintf("Pread of .hash at %lx failed\n",
                                    (long)hash);
                                goto badplt;
                        }
                }

#if defined(__sparc)
                if (sym.st_value != d[DI_PLTGOT]->d_un.d_ptr) {
                        dprintf("warning: DI_PLTGOT (%lx) doesn't match "
                            ".plt symbol pointer (%lx)",
                            (long)d[DI_PLTGOT]->d_un.d_ptr,
                            (long)sym.st_value);
                }
#endif /* __sparc */

                if (ndx == 0) {
                        dprintf(
                            "Failed to find \"_PROCEDURE_LINKAGE_TABLE_\"\n");
                        goto badplt;
                }

                sp->sh_name = SHSTR_NDX_plt;
                sp->sh_type = SHT_PROGBITS;
                sp->sh_flags = SHF_WRITE | SHF_ALLOC | SHF_EXECINSTR;
                sp->sh_addr = sym.st_value;
                if (ehdr->e_type == ET_DYN)
                        sp->sh_addr += addr;
                sp->sh_offset = off;
                sp->sh_size = pltsz;
                sp->sh_link = 0;
                sp->sh_info = 0;
                sp->sh_addralign = SH_ADDRALIGN;
                sp->sh_entsize = M_PLT_ENTSIZE;

                if (Pread(P, &elfdata[off], sp->sh_size, sp->sh_addr) !=
                    sp->sh_size) {
                        dprintf("failed to read .plt at %lx\n",
                            (long)sp->sh_addr);
                        goto badplt;
                }
                off += roundup(sp->sh_size, SH_ADDRALIGN);
                sp++;
        }

badplt:
        /* make sure we didn't write past the end of allocated memory */
        sp++;
        assert(((uintptr_t)(sp) - 1) < ((uintptr_t)elfdata + size));

        free(dp);
        if ((elf = elf_memory(elfdata, size)) == NULL) {
                dprintf("failed to create ELF object "
                    "in memory for size %ld\n", (long)size);
                free(elfdata);
                return (NULL);
        }

        fptr->file_elfmem = elfdata;

        return (elf);

bad:
        if (dp != NULL)
                free(dp);
        if (elfdata != NULL)
                free(elfdata);
        return (NULL);
}