dt_link.c   [plain text]

/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident	"@(#)dt_link.c	1.20	08/05/05 SMI"

#if defined(__APPLE__)

#include <dt_impl.h>
#include <dt_provider.h>
#include <dt_program.h>
#include <dt_string.h>

int
dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
		    const char *file, int objc, char *const objv[])
{
        return 0;
}

#else

#define ELF_TARGET_ALL
#include <elf.h>

#include <sys/types.h>
#include <sys/sysmacros.h>

#include <unistd.h>
#include <strings.h>
#include <alloca.h>
#include <limits.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <wait.h>
#include <assert.h>
#include <sys/ipc.h>

#include <dt_impl.h>
#include <dt_provider.h>
#include <dt_program.h>
#include <dt_string.h>

#define ESHDR_NULL      0
#define ESHDR_SHSTRTAB  1
#define ESHDR_DOF       2
#define ESHDR_STRTAB    3
#define ESHDR_SYMTAB    4
#define ESHDR_REL       5
#define ESHDR_NUM       6

#define PWRITE_SCN(index, data) \
(lseek64(fd, (off64_t)elf_file.shdr[(index)].sh_offset, SEEK_SET) != \
(off64_t)elf_file.shdr[(index)].sh_offset || \
dt_write(dtp, fd, (data), elf_file.shdr[(index)].sh_size) != \
elf_file.shdr[(index)].sh_size)

static const char DTRACE_SHSTRTAB32[] = "\0"
".shstrtab\0"           /* 1 */
".SUNW_dof\0"           /* 11 */
".strtab\0"             /* 21 */
".symtab\0"             /* 29 */
#ifdef __sparc
".rela.SUNW_dof";       /* 37 */
#else
".rel.SUNW_dof";        /* 37 */
#endif

static const char DTRACE_SHSTRTAB64[] = "\0"
".shstrtab\0"           /* 1 */
".SUNW_dof\0"           /* 11 */
".strtab\0"             /* 21 */
".symtab\0"             /* 29 */
".rela.SUNW_dof";       /* 37 */

static const char DOFSTR[] = "__SUNW_dof";
static const char DOFLAZYSTR[] = "___SUNW_dof";

typedef struct dt_link_pair {
        struct dt_link_pair *dlp_next;  /* next pair in linked list */
        void *dlp_str;                  /* buffer for string table */
        void *dlp_sym;                  /* buffer for symbol table */
} dt_link_pair_t;

typedef struct dof_elf32 {
        uint32_t de_nrel;               /* relocation count */
#ifdef __sparc
        Elf32_Rela *de_rel;             /* array of relocations for sparc */
#else
        Elf32_Rel *de_rel;              /* array of relocations for x86 */
#endif
        uint32_t de_nsym;               /* symbol count */
        Elf32_Sym *de_sym;              /* array of symbols */
        uint32_t de_strlen;             /* size of of string table */
        char *de_strtab;                /* string table */
        uint32_t de_global;             /* index of the first global symbol */
} dof_elf32_t;

static int
prepare_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf32_t *dep)
{
        dof_sec_t *dofs, *s;
        dof_relohdr_t *dofrh;
        dof_relodesc_t *dofr;
        char *strtab;
        int i, j, nrel;
        size_t strtabsz = 1;
        uint32_t count = 0;
        size_t base;
        Elf32_Sym *sym;
#ifdef __sparc
        Elf32_Rela *rel;
#else
        Elf32_Rel *rel;
#endif
	
        /*LINTED*/
        dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff);
	
        /*
         * First compute the size of the string table and the number of
         * relocations present in the DOF.
         */
        for (i = 0; i < dof->dofh_secnum; i++) {
                if (dofs[i].dofs_type != DOF_SECT_URELHDR)
                        continue;
		
                /*LINTED*/
                dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
		
                s = &dofs[dofrh->dofr_strtab];
                strtab = (char *)dof + s->dofs_offset;
                assert(strtab[0] == '\0');
                strtabsz += s->dofs_size - 1;
		
                s = &dofs[dofrh->dofr_relsec];
                /*LINTED*/
                dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
                count += s->dofs_size / s->dofs_entsize;
        }
	
        dep->de_strlen = strtabsz;
        dep->de_nrel = count;
        dep->de_nsym = count + 1; /* the first symbol is always null */
	
        if (dtp->dt_lazyload) {
                dep->de_strlen += sizeof (DOFLAZYSTR);
                dep->de_nsym++;
        } else {
                dep->de_strlen += sizeof (DOFSTR);
                dep->de_nsym++;
        }
	
        if ((dep->de_rel = calloc(dep->de_nrel,
				  sizeof (dep->de_rel[0]))) == NULL) {
                return (dt_set_errno(dtp, EDT_NOMEM));
        }
	
        if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf32_Sym))) == NULL) {
                free(dep->de_rel);
                return (dt_set_errno(dtp, EDT_NOMEM));
        }
	
        if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) {
                free(dep->de_rel);
                free(dep->de_sym);
                return (dt_set_errno(dtp, EDT_NOMEM));
        }
	
        count = 0;
        strtabsz = 1;
        dep->de_strtab[0] = '\0';
        rel = dep->de_rel;
        sym = dep->de_sym;
        dep->de_global = 1;
	
        /*
         * The first symbol table entry must be zeroed and is always ignored.
         */
        bzero(sym, sizeof (Elf32_Sym));
        sym++;
	
        /*
         * Take a second pass through the DOF sections filling in the
         * memory we allocated.
         */
        for (i = 0; i < dof->dofh_secnum; i++) {
                if (dofs[i].dofs_type != DOF_SECT_URELHDR)
                        continue;
		
                /*LINTED*/
                dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
		
                s = &dofs[dofrh->dofr_strtab];
                strtab = (char *)dof + s->dofs_offset;
                bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size);
                base = strtabsz;
                strtabsz += s->dofs_size - 1;
		
                s = &dofs[dofrh->dofr_relsec];
                /*LINTED*/
                dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
                nrel = s->dofs_size / s->dofs_entsize;
		
                s = &dofs[dofrh->dofr_tgtsec];
		
                for (j = 0; j < nrel; j++) {
#if defined(__i386) || defined(__amd64)
                        rel->r_offset = s->dofs_offset +
			dofr[j].dofr_offset;
                        rel->r_info = ELF32_R_INFO(count + dep->de_global,
						   R_386_32);
#elif defined(__sparc)
                        /*
                         * Add 4 bytes to hit the low half of this 64-bit
                         * big-endian address.
                         */
                        rel->r_offset = s->dofs_offset +
			dofr[j].dofr_offset + 4;
                        rel->r_info = ELF32_R_INFO(count + dep->de_global,
						   R_SPARC_32);
#else
#error unknown ISA
#endif
			
                        sym->st_name = base + dofr[j].dofr_name - 1;
                        sym->st_value = 0;
                        sym->st_size = 0;
                        sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC);
                        sym->st_other = 0;
                        sym->st_shndx = SHN_UNDEF;
			
                        rel++;
                        sym++;
                        count++;
                }
        }
	
        /*
         * Add a symbol for the DOF itself. We use a different symbol for
         * lazily and actively loaded DOF to make them easy to distinguish.
         */
        sym->st_name = strtabsz;
        sym->st_value = 0;
        sym->st_size = dof->dofh_filesz;
        sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_OBJECT);
        sym->st_other = 0;
        sym->st_shndx = ESHDR_DOF;
        sym++;
	
        if (dtp->dt_lazyload) {
                bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz,
		      sizeof (DOFLAZYSTR));
                strtabsz += sizeof (DOFLAZYSTR);
        } else {
                bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR));
                strtabsz += sizeof (DOFSTR);
        }
	
        assert(count == dep->de_nrel);
        assert(strtabsz == dep->de_strlen);
	
        return (0);
}


typedef struct dof_elf64 {
        uint32_t de_nrel;
        Elf64_Rela *de_rel;
        uint32_t de_nsym;
        Elf64_Sym *de_sym;
	
        uint32_t de_strlen;
        char *de_strtab;
	
        uint32_t de_global;
} dof_elf64_t;

static int
prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep)
{
        dof_sec_t *dofs, *s;
        dof_relohdr_t *dofrh;
        dof_relodesc_t *dofr;
        char *strtab;
        int i, j, nrel;
        size_t strtabsz = 1;
        uint32_t count = 0;
        size_t base;
        Elf64_Sym *sym;
        Elf64_Rela *rel;
	
        /*LINTED*/
        dofs = (dof_sec_t *)((char *)dof + dof->dofh_secoff);
	
        /*
         * First compute the size of the string table and the number of
         * relocations present in the DOF.
         */
        for (i = 0; i < dof->dofh_secnum; i++) {
                if (dofs[i].dofs_type != DOF_SECT_URELHDR)
                        continue;
		
                /*LINTED*/
                dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
		
                s = &dofs[dofrh->dofr_strtab];
                strtab = (char *)dof + s->dofs_offset;
                assert(strtab[0] == '\0');
                strtabsz += s->dofs_size - 1;
		
                s = &dofs[dofrh->dofr_relsec];
                /*LINTED*/
                dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
                count += s->dofs_size / s->dofs_entsize;
        }
	
        dep->de_strlen = strtabsz;
        dep->de_nrel = count;
        dep->de_nsym = count + 1; /* the first symbol is always null */
	
        if (dtp->dt_lazyload) {
                dep->de_strlen += sizeof (DOFLAZYSTR);
                dep->de_nsym++;
        } else {
                dep->de_strlen += sizeof (DOFSTR);
                dep->de_nsym++;
        }
	
        if ((dep->de_rel = calloc(dep->de_nrel,
				  sizeof (dep->de_rel[0]))) == NULL) {
                return (dt_set_errno(dtp, EDT_NOMEM));
        }
	
        if ((dep->de_sym = calloc(dep->de_nsym, sizeof (Elf64_Sym))) == NULL) {
                free(dep->de_rel);
                return (dt_set_errno(dtp, EDT_NOMEM));
        }
	
        if ((dep->de_strtab = calloc(dep->de_strlen, 1)) == NULL) {
                free(dep->de_rel);
                free(dep->de_sym);
                return (dt_set_errno(dtp, EDT_NOMEM));
        }
	
        count = 0;
        strtabsz = 1;
        dep->de_strtab[0] = '\0';
        rel = dep->de_rel;
        sym = dep->de_sym;
        dep->de_global = 1;
	
        /*
         * The first symbol table entry must be zeroed and is always ignored.
         */
        bzero(sym, sizeof (Elf64_Sym));
        sym++;
	
        /*
         * Take a second pass through the DOF sections filling in the
         * memory we allocated.
         */
        for (i = 0; i < dof->dofh_secnum; i++) {
                if (dofs[i].dofs_type != DOF_SECT_URELHDR)
                        continue;
		
                /*LINTED*/
                dofrh = (dof_relohdr_t *)((char *)dof + dofs[i].dofs_offset);
		
                s = &dofs[dofrh->dofr_strtab];
                strtab = (char *)dof + s->dofs_offset;
                bcopy(strtab + 1, dep->de_strtab + strtabsz, s->dofs_size);
                base = strtabsz;
                strtabsz += s->dofs_size - 1;
		
                s = &dofs[dofrh->dofr_relsec];
                /*LINTED*/
                dofr = (dof_relodesc_t *)((char *)dof + s->dofs_offset);
                nrel = s->dofs_size / s->dofs_entsize;
		
                s = &dofs[dofrh->dofr_tgtsec];
		
                for (j = 0; j < nrel; j++) {
#if defined(__i386) || defined(__amd64)
                        rel->r_offset = s->dofs_offset +
			dofr[j].dofr_offset;
                        rel->r_info = ELF64_R_INFO(count + dep->de_global,
						   R_AMD64_64);
#elif defined(__sparc)
                        rel->r_offset = s->dofs_offset +
			dofr[j].dofr_offset;
                        rel->r_info = ELF64_R_INFO(count + dep->de_global,
						   R_SPARC_64);
#else
#error unknown ISA
#endif
			
                        sym->st_name = base + dofr[j].dofr_name - 1;
                        sym->st_value = 0;
                        sym->st_size = 0;
                        sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC);
                        sym->st_other = 0;
                        sym->st_shndx = SHN_UNDEF;
			
                        rel++;
                        sym++;
                        count++;
                }
        }
	
        /*
         * Add a symbol for the DOF itself. We use a different symbol for
         * lazily and actively loaded DOF to make them easy to distinguish.
         */
        sym->st_name = strtabsz;
        sym->st_value = 0;
        sym->st_size = dof->dofh_filesz;
        sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_OBJECT);
        sym->st_other = 0;
        sym->st_shndx = ESHDR_DOF;
        sym++;
	
        if (dtp->dt_lazyload) {
                bcopy(DOFLAZYSTR, dep->de_strtab + strtabsz,
		      sizeof (DOFLAZYSTR));
                strtabsz += sizeof (DOFLAZYSTR);
        } else {
                bcopy(DOFSTR, dep->de_strtab + strtabsz, sizeof (DOFSTR));
                strtabsz += sizeof (DOFSTR);
        }
	
        assert(count == dep->de_nrel);
        assert(strtabsz == dep->de_strlen);
	
        return (0);
}

/*
 * Write out an ELF32 file prologue consisting of a header, section headers,
 * and a section header string table.  The DOF data will follow this prologue
 * and complete the contents of the given ELF file.
 */
static int
dump_elf32(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
{
        struct {
                Elf32_Ehdr ehdr;
                Elf32_Shdr shdr[ESHDR_NUM];
        } elf_file;
	
        Elf32_Shdr *shp;
        Elf32_Off off;
        dof_elf32_t de;
        int ret = 0;
        uint_t nshdr;
	
        if (prepare_elf32(dtp, dof, &de) != 0)
                return (-1); /* errno is set for us */
	
        /*
         * If there are no relocations, we only need enough sections for
         * the shstrtab and the DOF.
         */
        nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM;
	
        bzero(&elf_file, sizeof (elf_file));
	
        elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0;
        elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1;
        elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2;
        elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3;
        elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT;
        elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS32;
#if defined(_BIG_ENDIAN)
        elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
#elif defined(_LITTLE_ENDIAN)
        elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
#endif
        elf_file.ehdr.e_type = ET_REL;
#if defined(__sparc)
        elf_file.ehdr.e_machine = EM_SPARC;
#elif defined(__i386) || defined(__amd64)
        elf_file.ehdr.e_machine = EM_386;
#endif
        elf_file.ehdr.e_version = EV_CURRENT;
        elf_file.ehdr.e_shoff = sizeof (Elf32_Ehdr);
        elf_file.ehdr.e_ehsize = sizeof (Elf32_Ehdr);
        elf_file.ehdr.e_phentsize = sizeof (Elf32_Phdr);
        elf_file.ehdr.e_shentsize = sizeof (Elf32_Shdr);
        elf_file.ehdr.e_shnum = nshdr;
        elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB;
        off = sizeof (elf_file) + nshdr * sizeof (Elf32_Shdr);
	
        shp = &elf_file.shdr[ESHDR_SHSTRTAB];
        shp->sh_name = 1; /* DTRACE_SHSTRTAB32[1] = ".shstrtab" */
        shp->sh_type = SHT_STRTAB;
        shp->sh_offset = off;
        shp->sh_size = sizeof (DTRACE_SHSTRTAB32);
        shp->sh_addralign = sizeof (char);
        off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
	
        shp = &elf_file.shdr[ESHDR_DOF];
        shp->sh_name = 11; /* DTRACE_SHSTRTAB32[11] = ".SUNW_dof" */
        shp->sh_flags = SHF_ALLOC;
        shp->sh_type = SHT_SUNW_dof;
        shp->sh_offset = off;
        shp->sh_size = dof->dofh_filesz;
        shp->sh_addralign = 8;
        off = shp->sh_offset + shp->sh_size;
	
        shp = &elf_file.shdr[ESHDR_STRTAB];
        shp->sh_name = 21; /* DTRACE_SHSTRTAB32[21] = ".strtab" */
        shp->sh_flags = SHF_ALLOC;
        shp->sh_type = SHT_STRTAB;
        shp->sh_offset = off;
        shp->sh_size = de.de_strlen;
        shp->sh_addralign = sizeof (char);
        off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4);
	
        shp = &elf_file.shdr[ESHDR_SYMTAB];
        shp->sh_name = 29; /* DTRACE_SHSTRTAB32[29] = ".symtab" */
        shp->sh_flags = SHF_ALLOC;
        shp->sh_type = SHT_SYMTAB;
        shp->sh_entsize = sizeof (Elf32_Sym);
        shp->sh_link = ESHDR_STRTAB;
        shp->sh_offset = off;
        shp->sh_info = de.de_global;
        shp->sh_size = de.de_nsym * sizeof (Elf32_Sym);
        shp->sh_addralign = 4;
        off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 4);
	
        if (de.de_nrel == 0) {
                if (dt_write(dtp, fd, &elf_file,
			     sizeof (elf_file)) != sizeof (elf_file) ||
                    PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) ||
                    PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
                    PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
                    PWRITE_SCN(ESHDR_DOF, dof)) {
                        ret = dt_set_errno(dtp, errno);
                }
        } else {
                shp = &elf_file.shdr[ESHDR_REL];
                shp->sh_name = 37; /* DTRACE_SHSTRTAB32[37] = ".rel.SUNW_dof" */
                shp->sh_flags = SHF_ALLOC;
#ifdef __sparc
                shp->sh_type = SHT_RELA;
#else
                shp->sh_type = SHT_REL;
#endif
                shp->sh_entsize = sizeof (de.de_rel[0]);
                shp->sh_link = ESHDR_SYMTAB;
                shp->sh_info = ESHDR_DOF;
                shp->sh_offset = off;
                shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]);
                shp->sh_addralign = 4;
		
                if (dt_write(dtp, fd, &elf_file,
			     sizeof (elf_file)) != sizeof (elf_file) ||
                    PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB32) ||
                    PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
                    PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
                    PWRITE_SCN(ESHDR_REL, de.de_rel) ||
                    PWRITE_SCN(ESHDR_DOF, dof)) {
                        ret = dt_set_errno(dtp, errno);
                }
        }
	
        free(de.de_strtab);
        free(de.de_sym);
        free(de.de_rel);
	
        return (ret);
}

/*
 * Write out an ELF64 file prologue consisting of a header, section headers,
 * and a section header string table.  The DOF data will follow this prologue
 * and complete the contents of the given ELF file.
 */
static int
dump_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, int fd)
{
        struct {
                Elf64_Ehdr ehdr;
                Elf64_Shdr shdr[ESHDR_NUM];
        } elf_file;
	
        Elf64_Shdr *shp;
        Elf64_Off off;
        dof_elf64_t de;
        int ret = 0;
        uint_t nshdr;
	
        if (prepare_elf64(dtp, dof, &de) != 0)
                return (-1); /* errno is set for us */
	
        /*
         * If there are no relocations, we only need enough sections for
         * the shstrtab and the DOF.
         */
        nshdr = de.de_nrel == 0 ? ESHDR_SYMTAB + 1 : ESHDR_NUM;
	
        bzero(&elf_file, sizeof (elf_file));
	
        elf_file.ehdr.e_ident[EI_MAG0] = ELFMAG0;
        elf_file.ehdr.e_ident[EI_MAG1] = ELFMAG1;
        elf_file.ehdr.e_ident[EI_MAG2] = ELFMAG2;
        elf_file.ehdr.e_ident[EI_MAG3] = ELFMAG3;
        elf_file.ehdr.e_ident[EI_VERSION] = EV_CURRENT;
        elf_file.ehdr.e_ident[EI_CLASS] = ELFCLASS64;
#if defined(_BIG_ENDIAN)
        elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2MSB;
#elif defined(_LITTLE_ENDIAN)
        elf_file.ehdr.e_ident[EI_DATA] = ELFDATA2LSB;
#endif
        elf_file.ehdr.e_type = ET_REL;
#if defined(__sparc)
        elf_file.ehdr.e_machine = EM_SPARCV9;
#elif defined(__i386) || defined(__amd64)
        elf_file.ehdr.e_machine = EM_AMD64;
#endif
        elf_file.ehdr.e_version = EV_CURRENT;
        elf_file.ehdr.e_shoff = sizeof (Elf64_Ehdr);
        elf_file.ehdr.e_ehsize = sizeof (Elf64_Ehdr);
        elf_file.ehdr.e_phentsize = sizeof (Elf64_Phdr);
        elf_file.ehdr.e_shentsize = sizeof (Elf64_Shdr);
        elf_file.ehdr.e_shnum = nshdr;
        elf_file.ehdr.e_shstrndx = ESHDR_SHSTRTAB;
        off = sizeof (elf_file) + nshdr * sizeof (Elf64_Shdr);
	
        shp = &elf_file.shdr[ESHDR_SHSTRTAB];
        shp->sh_name = 1; /* DTRACE_SHSTRTAB64[1] = ".shstrtab" */
        shp->sh_type = SHT_STRTAB;
        shp->sh_offset = off;
        shp->sh_size = sizeof (DTRACE_SHSTRTAB64);
        shp->sh_addralign = sizeof (char);
        off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
	
        shp = &elf_file.shdr[ESHDR_DOF];
        shp->sh_name = 11; /* DTRACE_SHSTRTAB64[11] = ".SUNW_dof" */
        shp->sh_flags = SHF_ALLOC;
        shp->sh_type = SHT_SUNW_dof;
        shp->sh_offset = off;
        shp->sh_size = dof->dofh_filesz;
        shp->sh_addralign = 8;
        off = shp->sh_offset + shp->sh_size;
	
        shp = &elf_file.shdr[ESHDR_STRTAB];
        shp->sh_name = 21; /* DTRACE_SHSTRTAB64[21] = ".strtab" */
        shp->sh_flags = SHF_ALLOC;
        shp->sh_type = SHT_STRTAB;
        shp->sh_offset = off;
        shp->sh_size = de.de_strlen;
        shp->sh_addralign = sizeof (char);
        off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
	
        shp = &elf_file.shdr[ESHDR_SYMTAB];
        shp->sh_name = 29; /* DTRACE_SHSTRTAB64[29] = ".symtab" */
        shp->sh_flags = SHF_ALLOC;
        shp->sh_type = SHT_SYMTAB;
        shp->sh_entsize = sizeof (Elf64_Sym);
        shp->sh_link = ESHDR_STRTAB;
        shp->sh_offset = off;
        shp->sh_info = de.de_global;
        shp->sh_size = de.de_nsym * sizeof (Elf64_Sym);
        shp->sh_addralign = 8;
        off = P2ROUNDUP(shp->sh_offset + shp->sh_size, 8);
	
        if (de.de_nrel == 0) {
                if (dt_write(dtp, fd, &elf_file,
			     sizeof (elf_file)) != sizeof (elf_file) ||
                    PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) ||
                    PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
                    PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
                    PWRITE_SCN(ESHDR_DOF, dof)) {
                        ret = dt_set_errno(dtp, errno);
                }
        } else {
                shp = &elf_file.shdr[ESHDR_REL];
                shp->sh_name = 37; /* DTRACE_SHSTRTAB64[37] = ".rel.SUNW_dof" */
                shp->sh_flags = SHF_ALLOC;
                shp->sh_type = SHT_RELA;
                shp->sh_entsize = sizeof (de.de_rel[0]);
                shp->sh_link = ESHDR_SYMTAB;
                shp->sh_info = ESHDR_DOF;
                shp->sh_offset = off;
                shp->sh_size = de.de_nrel * sizeof (de.de_rel[0]);
                shp->sh_addralign = 8;
		
                if (dt_write(dtp, fd, &elf_file,
			     sizeof (elf_file)) != sizeof (elf_file) ||
                    PWRITE_SCN(ESHDR_SHSTRTAB, DTRACE_SHSTRTAB64) ||
                    PWRITE_SCN(ESHDR_STRTAB, de.de_strtab) ||
                    PWRITE_SCN(ESHDR_SYMTAB, de.de_sym) ||
                    PWRITE_SCN(ESHDR_REL, de.de_rel) ||
                    PWRITE_SCN(ESHDR_DOF, dof)) {
                        ret = dt_set_errno(dtp, errno);
                }
        }
	
        free(de.de_strtab);
        free(de.de_sym);
        free(de.de_rel);
	
        return (ret);
}

static int
dt_symtab_lookup(Elf_Data *data_sym, int nsym, uintptr_t addr, uint_t shn,
    GElf_Sym *sym)
{
        int i, ret = -1;
        GElf_Sym s;
	
	for (i = 0; i < nsym && gelf_getsym(data_sym, i, sym) != NULL; i++) {
                if (GELF_ST_TYPE(sym->st_info) == STT_FUNC &&
                    shn == sym->st_shndx &&
                    sym->st_value <= addr &&
                    addr < sym->st_value + sym->st_size) {
                        if (GELF_ST_BIND(sym->st_info) == STB_GLOBAL)
                                return (0);
			
                        ret = 0;
                        s = *sym;
                }
        }
	
        if (ret == 0)
	*sym = s;
        return (ret);
}

#if defined(__sparc)

#define DT_OP_RET               0x81c7e008
#define DT_OP_NOP               0x01000000
#define DT_OP_CALL              0x40000000
#define DT_OP_CLR_O0            0x90102000

#define DT_IS_MOV_O7(inst)      (((inst) & 0xffffe000) == 0x9e100000)
#define DT_IS_RESTORE(inst)     (((inst) & 0xc1f80000) == 0x81e80000)
#define DT_IS_RETL(inst)        (((inst) & 0xfff83fff) == 0x81c02008)

#define DT_RS2(inst)            ((inst) & 0x1f)
#define DT_MAKE_RETL(reg)       (0x81c02008 | ((reg) << 14))

/*ARGSUSED*/
static int
dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela,
	   uint32_t *off)
{
        uint32_t *ip;
	
        if ((rela->r_offset & (sizeof (uint32_t) - 1)) != 0)
                return (-1);
	
        /*LINTED*/
        ip = (uint32_t *)(p + rela->r_offset);
	
        /*
         * We only know about some specific relocation types.
         */
        if (GELF_R_TYPE(rela->r_info) != R_SPARC_WDISP30 &&
            GELF_R_TYPE(rela->r_info) != R_SPARC_WPLT30)
	return (-1);
	
        /*
         * We may have already processed this object file in an earlier linker
         * invocation. Check to see if the present instruction sequence matches
	 * the one we would install below.
         */
        if (isenabled) {
		if (ip[0] == DT_OP_NOP) {
			(*off) += sizeof (ip[0]);
                        return (0);
		}
        } else {
                if (DT_IS_RESTORE(ip[1])) {
			if (ip[0] == DT_OP_RET) {
				(*off) += sizeof (ip[0]);
                                return (0);
			}
                } else if (DT_IS_MOV_O7(ip[1])) {
                        if (DT_IS_RETL(ip[0]))
                                return (0);
                } else {
                        if (ip[0] == DT_OP_NOP) {
                                (*off) += sizeof (ip[0]);
                                return (0);
                        }
                }
        }
	
        /*
         * We only expect call instructions with a displacement of 0.
         */
        if (ip[0] != DT_OP_CALL) {
                dt_dprintf("found %x instead of a call instruction at %llx\n",
			   ip[0], (u_longlong_t)rela->r_offset);
                return (-1);
        }
	
        if (isenabled) {
                /*
                 * It would necessarily indicate incorrect usage if an is-
                 * enabled probe were tail-called so flag that as an error.
                 * It's also potentially (very) tricky to handle gracefully,
                 * but could be done if this were a desired use scenario.
                 */
                if (DT_IS_RESTORE(ip[1]) || DT_IS_MOV_O7(ip[1])) {
                        dt_dprintf("tail call to is-enabled probe at %llx\n",
				   (u_longlong_t)rela->r_offset);
                        return (-1);
                }
		

		/*
		 * On SPARC, we take advantage of the fact that the first
		 * argument shares the same register as for the return value.
		 * The macro handles the work of zeroing that register so we
		 * don't need to do anything special here. We instrument the
		 * instruction in the delay slot as we'll need to modify the
		 * return register after that instruction has been emulated.
		 */
		ip[0] = DT_OP_NOP;
		(*off) += sizeof (ip[0]);
        } else {
                /*
                 * If the call is followed by a restore, it's a tail call so
                 * change the call to a ret. If the call if followed by a mov
                 * of a register into %o7, it's a tail call in leaf context
                 * so change the call to a retl-like instruction that returns
                 * to that register value + 8 (rather than the typical %o7 +
		 * 8); the delay slot instruction is left, but should have no
		 * effect. Otherwise we change the call to be a nop. We
		 * identify the subsequent instruction as the probe point in
		 * all but the leaf tail-call case to ensure that arguments to
		 * the probe are complete and consistent. An astute, though
		 * largely hypothetical, observer would note that there is the
		 * possibility of a false-positive probe firing if the function
		 * contained a branch to the instruction in the delay slot of
		 * the call. Fixing this would require significant in-kernel
		 * modifications, and isn't worth doing until we see it in the
		 * wild.
                 */
                if (DT_IS_RESTORE(ip[1])) {
                        ip[0] = DT_OP_RET;
			(*off) += sizeof (ip[0]);
                } else if (DT_IS_MOV_O7(ip[1])) {
                        ip[0] = DT_MAKE_RETL(DT_RS2(ip[1]));
                } else {
                        ip[0] = DT_OP_NOP;
                        (*off) += sizeof (ip[0]);
                }
        }
	
        return (0);
}

#elif defined(__i386) || defined(__amd64)

#define DT_OP_NOP               0x90
#define	DT_OP_RET		0xc3
#define DT_OP_CALL              0xe8
#define	DT_OP_JMP32		0xe9
#define DT_OP_REX_RAX           0x48
#define DT_OP_XOR_EAX_0         0x33
#define DT_OP_XOR_EAX_1         0xc0

static int
dt_modtext(dtrace_hdl_t *dtp, char *p, int isenabled, GElf_Rela *rela,
	   uint32_t *off)
{
        uint8_t *ip = (uint8_t *)(p + rela->r_offset - 1);
	uint8_t ret;
	
        /*
         * On x86, the first byte of the instruction is the call opcode and
         * the next four bytes are the 32-bit address; the relocation is for
         * the address operand. We back up the offset to the first byte of
         * the instruction. For is-enabled probes, we later advance the offset
         * so that it hits the first nop in the instruction sequence.
         */
        (*off) -= 1;
	
        /*
         * We only know about some specific relocation types. Luckily
         * these types have the same values on both 32-bit and 64-bit
         * x86 architectures.
         */
        if (GELF_R_TYPE(rela->r_info) != R_386_PC32 &&
            GELF_R_TYPE(rela->r_info) != R_386_PLT32)
	return (-1);
	
        /*
         * We may have already processed this object file in an earlier linker
         * invocation. Check to see if the present instruction sequence matches
         * the one we would install. For is-enabled probes, we advance the
	 * offset to the first nop instruction in the sequence to match the
	 * text modification code below.
         */
        if (!isenabled) {
		if ((ip[0] == DT_OP_NOP || ip[0] == DT_OP_RET) &&
		    ip[1] == DT_OP_NOP && ip[2] == DT_OP_NOP &&
		    ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP)
		return (0);
        } else if (dtp->dt_oflags & DTRACE_O_LP64) {
                if (ip[0] == DT_OP_REX_RAX &&
                    ip[1] == DT_OP_XOR_EAX_0 && ip[2] == DT_OP_XOR_EAX_1 &&
		    (ip[3] == DT_OP_NOP || ip[3] == DT_OP_RET) &&
		    ip[4] == DT_OP_NOP) {
                        (*off) += 3;
                        return (0);
                }
        } else {
                if (ip[0] == DT_OP_XOR_EAX_0 && ip[1] == DT_OP_XOR_EAX_1 &&
		    (ip[2] == DT_OP_NOP || ip[2] == DT_OP_RET) &&
		    ip[3] == DT_OP_NOP && ip[4] == DT_OP_NOP) {
                        (*off) += 2;
                        return (0);
                }
        }
	
        /*
	 * We expect either a call instrution with a 32-bit displacement or a
	 * jmp instruction with a 32-bit displacement acting as a tail-call.
         */
	if (ip[0] != DT_OP_CALL && ip[0] != DT_OP_JMP32) {
		dt_dprintf("found %x instead of a call or jmp instruction at "
		    "%llx\n", ip[0], (u_longlong_t)rela->r_offset);
                return (-1);
        }
	
	ret = (ip[0] == DT_OP_JMP32) ? DT_OP_RET : DT_OP_NOP;

        /*
         * Establish the instruction sequence -- all nops for probes, and an
         * instruction to clear the return value register (%eax/%rax) followed
         * by nops for is-enabled probes. For is-enabled probes, we advance
         * the offset to the first nop. This isn't stricly necessary but makes
         * for more readable disassembly when the probe is enabled.
         */
        if (!isenabled) {
		ip[0] = ret;
                ip[1] = DT_OP_NOP;
                ip[2] = DT_OP_NOP;
                ip[3] = DT_OP_NOP;
                ip[4] = DT_OP_NOP;
        } else if (dtp->dt_oflags & DTRACE_O_LP64) {
                ip[0] = DT_OP_REX_RAX;
                ip[1] = DT_OP_XOR_EAX_0;
                ip[2] = DT_OP_XOR_EAX_1;
		ip[3] = ret;
                ip[4] = DT_OP_NOP;
                (*off) += 3;
        } else {
                ip[0] = DT_OP_XOR_EAX_0;
                ip[1] = DT_OP_XOR_EAX_1;
		ip[2] = ret;
                ip[3] = DT_OP_NOP;
                ip[4] = DT_OP_NOP;
                (*off) += 2;
        }
	
        return (0);
}

#else
#error unknown ISA
#endif

/*PRINTFLIKE5*/
static int
dt_link_error(dtrace_hdl_t *dtp, Elf *elf, int fd, dt_link_pair_t *bufs,
	      const char *format, ...)
{
        va_list ap;
        dt_link_pair_t *pair;
	
        va_start(ap, format);
        dt_set_errmsg(dtp, NULL, NULL, NULL, 0, format, ap);
        va_end(ap);
	
        if (elf != NULL)
                (void) elf_end(elf);
	
        if (fd >= 0)
                (void) close(fd);
	
        while ((pair = bufs) != NULL) {
                bufs = pair->dlp_next;
                dt_free(dtp, pair->dlp_str);
                dt_free(dtp, pair->dlp_sym);
                dt_free(dtp, pair);
        }
	
        return (dt_set_errno(dtp, EDT_COMPILER));
}

static int
process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp)
{
        static const char dt_prefix[] = "__dtrace";
        static const char dt_enabled[] = "enabled";
        static const char dt_symprefix[] = "$dtrace";
        static const char dt_symfmt[] = "%s%d.%s";
        int fd, i, ndx, eprobe, mod = 0;
        Elf *elf = NULL;
        GElf_Ehdr ehdr;
        Elf_Scn *scn_rel, *scn_sym, *scn_str, *scn_tgt;
        Elf_Data *data_rel, *data_sym, *data_str, *data_tgt;
        GElf_Shdr shdr_rel, shdr_sym, shdr_str, shdr_tgt;
        GElf_Sym rsym, fsym, dsym;
        GElf_Rela rela;
        char *s, *p, *r;
        char pname[DTRACE_PROVNAMELEN];
        dt_provider_t *pvp;
        dt_probe_t *prp;
        uint32_t off, eclass, emachine1, emachine2;
        size_t symsize, nsym, isym, istr, len;
        key_t objkey;
        dt_link_pair_t *pair, *bufs = NULL;
        dt_strtab_t *strtab;
	
        if ((fd = open64(obj, O_RDWR)) == -1) {
                return (dt_link_error(dtp, elf, fd, bufs,
				      "failed to open %s: %s", obj, strerror(errno)));
        }
	
        if ((elf = elf_begin(fd, ELF_C_RDWR, NULL)) == NULL) {
                return (dt_link_error(dtp, elf, fd, bufs,
				      "failed to process %s: %s", obj, elf_errmsg(elf_errno())));
        }
	
        switch (elf_kind(elf)) {
        case ELF_K_ELF:
                break;
        case ELF_K_AR:
                return (dt_link_error(dtp, elf, fd, bufs, "archives are not "
				      "permitted; use the contents of the archive instead: %s",
				      obj));
        default:
                return (dt_link_error(dtp, elf, fd, bufs,
				      "invalid file type: %s", obj));
        }
	
        if (gelf_getehdr(elf, &ehdr) == NULL) {
                return (dt_link_error(dtp, elf, fd, bufs, "corrupt file: %s",
				      obj));
        }
	
        if (dtp->dt_oflags & DTRACE_O_LP64) {
                eclass = ELFCLASS64;
#if defined(__sparc)
                emachine1 = emachine2 = EM_SPARCV9;
#elif defined(__i386) || defined(__amd64)
                emachine1 = emachine2 = EM_AMD64;
#endif
                symsize = sizeof (Elf64_Sym);
        } else {
                eclass = ELFCLASS32;
#if defined(__sparc)
                emachine1 = EM_SPARC;
                emachine2 = EM_SPARC32PLUS;
#elif defined(__i386) || defined(__amd64)
                emachine1 = emachine2 = EM_386;
#endif
                symsize = sizeof (Elf32_Sym);
        }
	
        if (ehdr.e_ident[EI_CLASS] != eclass) {
                return (dt_link_error(dtp, elf, fd, bufs,
				      "incorrect ELF class for object file: %s", obj));
        }
	
        if (ehdr.e_machine != emachine1 && ehdr.e_machine != emachine2) {
                return (dt_link_error(dtp, elf, fd, bufs,
				      "incorrect ELF machine type for object file: %s", obj));
        }
	
        /*
         * We use this token as a relatively unique handle for this file on the
         * system in order to disambiguate potential conflicts between files of
         * the same name which contain identially named local symbols.
         */
        if ((objkey = ftok(obj, 0)) == (key_t)-1) {
                return (dt_link_error(dtp, elf, fd, bufs,
				      "failed to generate unique key for object file: %s", obj));
        }
	
        scn_rel = NULL;
        while ((scn_rel = elf_nextscn(elf, scn_rel)) != NULL) {
                if (gelf_getshdr(scn_rel, &shdr_rel) == NULL)
                        goto err;
		
                /*
                 * Skip any non-relocation sections.
                 */
                if (shdr_rel.sh_type != SHT_RELA && shdr_rel.sh_type != SHT_REL)
                        continue;
		
                if ((data_rel = elf_getdata(scn_rel, NULL)) == NULL)
                        goto err;
		
                /*
                 * Grab the section, section header and section data for the
                 * symbol table that this relocation section references.
                 */
                if ((scn_sym = elf_getscn(elf, shdr_rel.sh_link)) == NULL ||
                    gelf_getshdr(scn_sym, &shdr_sym) == NULL ||
                    (data_sym = elf_getdata(scn_sym, NULL)) == NULL)
		goto err;
		
                /*
                 * Ditto for that symbol table's string table.
                 */
                if ((scn_str = elf_getscn(elf, shdr_sym.sh_link)) == NULL ||
                    gelf_getshdr(scn_str, &shdr_str) == NULL ||
                    (data_str = elf_getdata(scn_str, NULL)) == NULL)
		goto err;
		
                /*
                 * Grab the section, section header and section data for the
                 * target section for the relocations. For the relocations
                 * we're looking for -- this will typically be the text of the
                 * object file.
                 */
                if ((scn_tgt = elf_getscn(elf, shdr_rel.sh_info)) == NULL ||
                    gelf_getshdr(scn_tgt, &shdr_tgt) == NULL ||
                    (data_tgt = elf_getdata(scn_tgt, NULL)) == NULL)
		goto err;
		
                /*
                 * We're looking for relocations to symbols matching this form:
                 *
                 *   __dtrace[enabled]_<prov>___<probe>
                 *
                 * For the generated object, we need to record the location
                 * identified by the relocation, and create a new relocation
                 * in the generated object that will be resolved at link time
                 * to the location of the function in which the probe is
                 * embedded. In the target object, we change the matched symbol
                 * so that it will be ignored at link time, and we modify the
                 * target (text) section to replace the call instruction with
                 * one or more nops.
                 *
                 * If the function containing the probe is locally scoped
                 * (static), we create an alias used by the relocation in the
                 * generated object. The alias, a new symbol, will be global
                 * (so that the relocation from the generated object can be
                 * resolved), and hidden (so that it is converted to a local
                 * symbol at link time). Such aliases have this form:
                 *
                 *   $dtrace<key>.<function>
                 *
                 * We take a first pass through all the relocations to
                 * populate our string table and count the number of extra
                 * symbols we'll require.
                 */
                strtab = dt_strtab_create(1);
                nsym = 0;
		isym = data_sym->d_size / symsize;
		istr = data_str->d_size;
		
                for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) {
			
                        if (shdr_rel.sh_type == SHT_RELA) {
                                if (gelf_getrela(data_rel, i, &rela) == NULL)
                                        continue;
                        } else {
                                GElf_Rel rel;
                                if (gelf_getrel(data_rel, i, &rel) == NULL)
                                        continue;
                                rela.r_offset = rel.r_offset;
                                rela.r_info = rel.r_info;
                                rela.r_addend = 0;
                        }
			
                        if (gelf_getsym(data_sym, GELF_R_SYM(rela.r_info),
					&rsym) == NULL) {
                                dt_strtab_destroy(strtab);
                                goto err;
                        }
			
                        s = (char *)data_str->d_buf + rsym.st_name;
			
                        if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0)
                                continue;
			
			if (dt_symtab_lookup(data_sym, isym, rela.r_offset,
					     shdr_rel.sh_info, &fsym) != 0) {
                                dt_strtab_destroy(strtab);
                                goto err;
                        }
			
                        if (GELF_ST_BIND(fsym.st_info) != STB_LOCAL)
                                continue;
			
                        if (fsym.st_name > data_str->d_size) {
                                dt_strtab_destroy(strtab);
                                goto err;
                        }
			
                        s = (char *)data_str->d_buf + fsym.st_name;
			
                        /*
                         * If this symbol isn't of type function, we've really
                         * driven off the rails or the object file is corrupt.
                         */
                        if (GELF_ST_TYPE(fsym.st_info) != STT_FUNC) {
                                dt_strtab_destroy(strtab);
                                return (dt_link_error(dtp, elf, fd, bufs,
						      "expected %s to be of type function", s));
                        }
			
                        len = snprintf(NULL, 0, dt_symfmt, dt_symprefix,
				       objkey, s) + 1;
                        if ((p = dt_alloc(dtp, len)) == NULL) {
                                dt_strtab_destroy(strtab);
                                goto err;
                        }
                        (void) snprintf(p, len, dt_symfmt, dt_symprefix,
					objkey, s);
			
                        if (dt_strtab_index(strtab, p) == -1) {
                                nsym++;
                                (void) dt_strtab_insert(strtab, p);
                        }
			
                        dt_free(dtp, p);
                }
		
                /*
                 * If needed, allocate the additional space for the symbol
                 * table and string table copying the old data into the new
                 * buffers, and marking the buffers as dirty. We inject those
                 * newly allocated buffers into the libelf data structures, but
                 * are still responsible for freeing them once we're done with
                 * the elf handle.
                 */
                if (nsym > 0) {
                        /*
                         * The first byte of the string table is reserved for
                         * the \0 entry.
                         */
                        len = dt_strtab_size(strtab) - 1;
			
                        assert(len > 0);
                        assert(dt_strtab_index(strtab, "") == 0);
			
                        dt_strtab_destroy(strtab);
			
                        if ((pair = dt_alloc(dtp, sizeof (*pair))) == NULL)
                                goto err;
			
                        if ((pair->dlp_str = dt_alloc(dtp, data_str->d_size +
						      len)) == NULL) {
                                dt_free(dtp, pair);
                                goto err;
                        }
			
                        if ((pair->dlp_sym = dt_alloc(dtp, data_sym->d_size +
						      nsym * symsize)) == NULL) {
                                dt_free(dtp, pair->dlp_str);
                                dt_free(dtp, pair);
                                goto err;
                        }
			
                        pair->dlp_next = bufs;
                        bufs = pair;
			
                        bcopy(data_str->d_buf, pair->dlp_str, data_str->d_size);
                        data_str->d_buf = pair->dlp_str;
                        data_str->d_size += len;
                        (void) elf_flagdata(data_str, ELF_C_SET, ELF_F_DIRTY);
			
                        shdr_str.sh_size += len;
                        (void) gelf_update_shdr(scn_str, &shdr_str);
			
                        bcopy(data_sym->d_buf, pair->dlp_sym, data_sym->d_size);
                        data_sym->d_buf = pair->dlp_sym;
                        data_sym->d_size += nsym * symsize;
                        (void) elf_flagdata(data_sym, ELF_C_SET, ELF_F_DIRTY);
			
                        shdr_sym.sh_size += nsym * symsize;
                        (void) gelf_update_shdr(scn_sym, &shdr_sym);
			
                        nsym += isym;
                } else {
                        dt_strtab_destroy(strtab);
                }
		
                /*
                 * Now that the tables have been allocated, perform the
                 * modifications described above.
                 */
                for (i = 0; i < shdr_rel.sh_size / shdr_rel.sh_entsize; i++) {
			
                        if (shdr_rel.sh_type == SHT_RELA) {
                                if (gelf_getrela(data_rel, i, &rela) == NULL)
                                        continue;
                        } else {
                                GElf_Rel rel;
                                if (gelf_getrel(data_rel, i, &rel) == NULL)
                                        continue;
                                rela.r_offset = rel.r_offset;
                                rela.r_info = rel.r_info;
                                rela.r_addend = 0;
                        }
			
                        ndx = GELF_R_SYM(rela.r_info);
			
                        if (gelf_getsym(data_sym, ndx, &rsym) == NULL ||
                            rsym.st_name > data_str->d_size)
			goto err;
			
                        s = (char *)data_str->d_buf + rsym.st_name;
			
                        if (strncmp(s, dt_prefix, sizeof (dt_prefix) - 1) != 0)
                                continue;
			
                        s += sizeof (dt_prefix) - 1;
			
                        /*
                         * Check to see if this is an 'is-enabled' check as
                         * opposed to a normal probe.
                         */
                        if (strncmp(s, dt_enabled,
				    sizeof (dt_enabled) - 1) == 0) {
                                s += sizeof (dt_enabled) - 1;
                                eprobe = 1;
                                *eprobesp = 1;
                                dt_dprintf("is-enabled probe\n");
                        } else {
                                eprobe = 0;
                                dt_dprintf("normal probe\n");
                        }
			
                        if (*s++ != '_')
                                goto err;
			
                        if ((p = strstr(s, "___")) == NULL ||
                            p - s >= sizeof (pname))
			goto err;
			
                        bcopy(s, pname, p - s);
                        pname[p - s] = '\0';
			
                        p = strhyphenate(p + 3); /* strlen("___") */
			
			if (dt_symtab_lookup(data_sym, isym, rela.r_offset,
					     shdr_rel.sh_info, &fsym) != 0)
			goto err;
			
                        if (fsym.st_name > data_str->d_size)
                                goto err;
			
                        assert(GELF_ST_TYPE(fsym.st_info) == STT_FUNC);
			
                        /*
                         * If a NULL relocation name is passed to
                         * dt_probe_define(), the function name is used for the
                         * relocation. The relocation needs to use a mangled
                         * name if the symbol is locally scoped; the function
                         * name may need to change if we've found the global
                         * alias for the locally scoped symbol (we prefer
                         * global symbols to locals in dt_symtab_lookup()).
                         */
                        s = (char *)data_str->d_buf + fsym.st_name;
                        r = NULL;
			
                        if (GELF_ST_BIND(fsym.st_info) == STB_LOCAL) {
                                dsym = fsym;
                                dsym.st_name = istr;
                                dsym.st_info = GELF_ST_INFO(STB_GLOBAL,
							    STT_FUNC);
				dsym.st_other =
				    ELF64_ST_VISIBILITY(STV_ELIMINATE);
                                (void) gelf_update_sym(data_sym, isym, &dsym);
				
                                r = (char *)data_str->d_buf + istr;
                                istr += 1 + sprintf(r, dt_symfmt,
						    dt_symprefix, objkey, s);
                                isym++;
                                assert(isym <= nsym);
				
                        } else if (strncmp(s, dt_symprefix,
					   strlen(dt_symprefix)) == 0) {
                                r = s;
                                if ((s = strchr(s, '.')) == NULL)
                                        goto err;
                                s++;
                        }
			
                        if ((pvp = dt_provider_lookup(dtp, pname)) == NULL) {
                                return (dt_link_error(dtp, elf, fd, bufs,
						      "no such provider %s", pname));
                        }
			
                        if ((prp = dt_probe_lookup(pvp, p)) == NULL) {
                                return (dt_link_error(dtp, elf, fd, bufs,
						      "no such probe %s", p));
                        }
			
                        assert(fsym.st_value <= rela.r_offset);
			
                        off = rela.r_offset - fsym.st_value;
                        if (dt_modtext(dtp, data_tgt->d_buf, eprobe,
				       &rela, &off) != 0) {
                                goto err;
                        }
			
                        if (dt_probe_define(pvp, prp, s, r, off, eprobe) != 0) {
                                return (dt_link_error(dtp, elf, fd, bufs,
						      "failed to allocate space for probe"));
                        }
			
                        mod = 1;
                        (void) elf_flagdata(data_tgt, ELF_C_SET, ELF_F_DIRTY);
			
                        /*
                         * This symbol may already have been marked to
                         * be ignored by another relocation referencing
                         * the same symbol or if this object file has
                         * already been processed by an earlier link
                         * invocation.
                         */
                        if (rsym.st_shndx != SHN_SUNW_IGNORE) {
                                rsym.st_shndx = SHN_SUNW_IGNORE;
                                (void) gelf_update_sym(data_sym, ndx, &rsym);
                        }
                }
        }
	
        if (mod && elf_update(elf, ELF_C_WRITE) == -1)
                goto err;
	
        (void) elf_end(elf);
        (void) close(fd);
	
        while ((pair = bufs) != NULL) {
                bufs = pair->dlp_next;
                dt_free(dtp, pair->dlp_str);
                dt_free(dtp, pair->dlp_sym);
                dt_free(dtp, pair);
        }
	
        return (0);
	
	err:
        return (dt_link_error(dtp, elf, fd, bufs,
			      "an error was encountered while processing %s", obj));
}

int
dtrace_program_link(dtrace_hdl_t *dtp, dtrace_prog_t *pgp, uint_t dflags,
		    const char *file, int objc, char *const objv[])
{
        char drti[PATH_MAX];
        dof_hdr_t *dof;
        int fd, status, i, cur;
        char *cmd, tmp;
        size_t len;
        int eprobes = 0, ret = 0;
	
        /*
         * A NULL program indicates a special use in which we just link
         * together a bunch of object files specified in objv and then
         * unlink(2) those object files.
         */
        if (pgp == NULL) {
                const char *fmt = "%s -o %s -r";
		
                len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file) + 1;
		
                for (i = 0; i < objc; i++)
                        len += strlen(objv[i]) + 1;
		
                cmd = alloca(len);
		
                cur = snprintf(cmd, len, fmt, dtp->dt_ld_path, file);
		
                for (i = 0; i < objc; i++)
                        cur += snprintf(cmd + cur, len - cur, " %s", objv[i]);
		
                if ((status = system(cmd)) == -1) {
                        return (dt_link_error(dtp, NULL, -1, NULL,
					      "failed to run %s: %s", dtp->dt_ld_path,
					      strerror(errno)));
                }
		
                if (WIFSIGNALED(status)) {
                        return (dt_link_error(dtp, NULL, -1, NULL,
					      "failed to link %s: %s failed due to signal %d",
					      file, dtp->dt_ld_path, WTERMSIG(status)));
                }
		
                if (WEXITSTATUS(status) != 0) {
                        return (dt_link_error(dtp, NULL, -1, NULL,
					      "failed to link %s: %s exited with status %d\n",
					      file, dtp->dt_ld_path, WEXITSTATUS(status)));
                }
		
                for (i = 0; i < objc; i++) {
                        if (strcmp(objv[i], file) != 0)
                                (void) unlink(objv[i]);
                }
		
                return (0);
        }
	
        for (i = 0; i < objc; i++) {
                if (process_obj(dtp, objv[i], &eprobes) != 0)
                        return (-1); /* errno is set for us */
        }
	
        /*
         * If there are is-enabled probes then we need to force use of DOF
         * version 2.
         */
        if (eprobes && pgp->dp_dofversion < DOF_VERSION_2)
                pgp->dp_dofversion = DOF_VERSION_2;
	
        if ((dof = dtrace_dof_create(dtp, pgp, dflags)) == NULL)
                return (-1); /* errno is set for us */
	
        /*
         * Create a temporary file and then unlink it if we're going to
         * combine it with drti.o later.  We can still refer to it in child
         * processes as /dev/fd/<fd>.
         */
        if ((fd = open64(file, O_RDWR | O_CREAT | O_TRUNC, 0666)) == -1) {
                return (dt_link_error(dtp, NULL, -1, NULL,
				      "failed to open %s: %s", file, strerror(errno)));
        }
	
        /*
         * If -xlinktype=DOF has been selected, just write out the DOF.
         * Otherwise proceed to the default of generating and linking ELF.
         */
        switch (dtp->dt_linktype) {
        case DT_LTYP_DOF:
                if (dt_write(dtp, fd, dof, dof->dofh_filesz) < dof->dofh_filesz)
                        ret = errno;
		
                if (close(fd) != 0 && ret == 0)
                        ret = errno;
		
                if (ret != 0) {
                        return (dt_link_error(dtp, NULL, -1, NULL,
					      "failed to write %s: %s", file, strerror(ret)));
                }
		
                return (0);
		
        case DT_LTYP_ELF:
                break; /* fall through to the rest of dtrace_program_link() */
		
        default:
                return (dt_link_error(dtp, NULL, -1, NULL,
				      "invalid link type %u\n", dtp->dt_linktype));
        }
	
	
        if (!dtp->dt_lazyload)
                (void) unlink(file);
	
        if (dtp->dt_oflags & DTRACE_O_LP64)
                status = dump_elf64(dtp, dof, fd);
        else
                status = dump_elf32(dtp, dof, fd);
	
        if (status != 0 || lseek(fd, 0, SEEK_SET) != 0) {
                return (dt_link_error(dtp, NULL, -1, NULL,
				      "failed to write %s: %s", file, strerror(errno)));
        }
	
        if (!dtp->dt_lazyload) {
                const char *fmt = "%s -o %s -r -Blocal -Breduce /dev/fd/%d %s";
		
                if (dtp->dt_oflags & DTRACE_O_LP64) {
                        (void) snprintf(drti, sizeof (drti),
					"%s/64/drti.o", _dtrace_libdir);
                } else {
                        (void) snprintf(drti, sizeof (drti),
					"%s/drti.o", _dtrace_libdir);
                }
		
                len = snprintf(&tmp, 1, fmt, dtp->dt_ld_path, file, fd,
			       drti) + 1;
		
                cmd = alloca(len);
		
                (void) snprintf(cmd, len, fmt, dtp->dt_ld_path, file, fd, drti);
		
                if ((status = system(cmd)) == -1) {
                        ret = dt_link_error(dtp, NULL, -1, NULL,
					    "failed to run %s: %s", dtp->dt_ld_path,
					    strerror(errno));
                        goto done;
                }
		
                (void) close(fd); /* release temporary file */
		
                if (WIFSIGNALED(status)) {
                        ret = dt_link_error(dtp, NULL, -1, NULL,
					    "failed to link %s: %s failed due to signal %d",
					    file, dtp->dt_ld_path, WTERMSIG(status));
                        goto done;
                }
		
                if (WEXITSTATUS(status) != 0) {
                        ret = dt_link_error(dtp, NULL, -1, NULL,
					    "failed to link %s: %s exited with status %d\n",
					    file, dtp->dt_ld_path, WEXITSTATUS(status));
                        goto done;
                }
        } else {
                (void) close(fd);
        }
	
	done:
        dtrace_dof_destroy(dtp, dof);
        return (ret);
}

#endif /* __APPLE__ */