IABSD.fr/src/libexec/ld.so/boot.c

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• Author : guenther
  Date : 2019-10-20 03:44:49
  Hash : 17fa8871
  Message : For more archs, ld.so itself only needs/uses the arch's "just add load offset" 'relative' relocation. Take advantage of that to simplify ld.so's self-reloc code: * give the exceptional archs (hppa and mips64) copies of the current boot.c as boot_md.c * teach the Makefile to use boot_md.c when present * reduce boot.c down to the minimum necessary to handle just relative reloc * teach the Makefile to fail if the built ld.so has other types of relocs ok visa@ kettenis@

• libexec/ld.so/boot.c

• /*	$OpenBSD: boot.c,v 1.18 2019/10/20 03:44:49 guenther Exp $ */
  
  /*
   * Copyright (c) 1998 Per Fogelstrom, Opsycon AB
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
   * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   *
   */
  
  /*
   * IMPORTANT: any functions below are NOT protected by SSP.  Please
   * do not add anything except what is required to reach GOT with
   * an adjustment.
   */
  
  #define	_DYN_LOADER
  
  #include <sys/exec_elf.h>
  
  #include "syscall.h"
  #include "archdep.h"
  
  #include "../../lib/csu/os-note-elf.h"
  
  #if RELOC_TAG == DT_RELA
  typedef	Elf_RelA	RELOC_TYPE;
  # define RELOCATE_RELATIVE(w, r, b)	*(w) = (r)->r_addend + (b)
  #elif RELOC_TAG == DT_REL
  typedef	Elf_Rel		RELOC_TYPE;
  # define RELOCATE_RELATIVE(w, r, b)	*(w) += (b)
  #else
  # error "unknown RELOC_TAG"
  #endif
  
  /*
   * Local decls.
   */
  void _dl_boot_bind(const long, long *, Elf_Dyn *) __boot;
  
  void
  _dl_boot_bind(const long sp, long *dl_data, Elf_Dyn *dynp)
  {
  	AuxInfo		*auxstack;
  	long		*stack;
  	int		n, argc;
  	char		**argv, **envp;
  	long		loff;
  	RELOC_TYPE	*dt_reloc;	/* DT_RELA   or DT_REL */
  	Elf_Word	dt_relocsz;	/* DT_RELASZ or DT_RELSZ */
  	RELOC_TYPE	*rend;
  
  	/*
  	 * Scan argument and environment vectors. Find dynamic
  	 * data vector put after them.
  	 */
  	stack = (long *)sp;
  	argc = *stack++;
  	argv = (char **)stack;
  	envp = &argv[argc + 1];
  	stack = (long *)envp;
  	while (*stack++ != 0L)
  		;
  
  	/*
  	 * Zero out dl_data.
  	 */
  	for (n = 0; n <= AUX_entry; n++)
  		dl_data[n] = 0;
  
  	/*
  	 * Dig out auxiliary data set up by exec call. Move all known
  	 * tags to an indexed local table for easy access.
  	 */
  	for (auxstack = (AuxInfo *)stack; auxstack->au_id != AUX_null;
  	    auxstack++) {
  		if (auxstack->au_id > AUX_entry)
  			continue;
  		dl_data[auxstack->au_id] = auxstack->au_v;
  	}
  	loff = dl_data[AUX_base];	/* XXX assumes ld.so is linked at 0x0 */
  
  	/*
  	 * Scan the DYNAMIC section for the loader for the two items we need
  	 */
  	dt_reloc = NULL;
  	dt_relocsz = 0;
  	while (dynp->d_tag != DT_NULL) {
  		if (dynp->d_tag == RELOC_TAG)		/* DT_{RELA,REL} */
  			dt_reloc = (void *)(dynp->d_un.d_ptr + loff);
  		else if (dynp->d_tag == RELOC_TAG+1)	/* DT_{RELA,REL}SZ */
  			dt_relocsz = dynp->d_un.d_val;
  		dynp++;
  	}
  
  	rend = (RELOC_TYPE *)((char *)dt_reloc + dt_relocsz);
  	for (; dt_reloc < rend; dt_reloc++) {
  		Elf_Addr *ra;
  
  		ra = (Elf_Addr *)(dt_reloc->r_offset + loff);
  		RELOCATE_RELATIVE(ra, dt_reloc, loff);
  	}
  }