entry.c revision 57ef7aa924e4bfdf3118d9b5b4285dfc94b632f3
/*
* 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 (c) 1988 AT&T
* All Rights Reserved
*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
#define ELF_TARGET_AMD64
#include <stdio.h>
#include <memory.h>
#include <debug.h>
#include "msg.h"
#include "_libld.h"
/*
* The loader uses a `segment descriptor' list to describe the output
* segments it can potentially create. This list is initially seeded
* using the templates contained in the sg_desc[] array below. Additional
* segments may be added using a mapfile.
*
* The entries in sg_desc[] must be put in the order defined by the
* Segment_id enum, such that a given LD_XXX value can serve as
* an index into sg_desc[] for the corresponding descriptor.
*
* The entries in sg_desc[] are initialized using the SG_DESC_INIT macro
* for two reasons:
*
* 1) The first field of the Sg_desc struct is a program header
* entry. ELF32_Phdr and ELF64_Phdr have the same fields,
* but their order is different. Use of a macro allows us
* to handle this transparently.
* 2) Most of the fields in the Sg_desc entries are set to 0.
* Use of a macro allows us to hide the clutter.
*/
#ifdef _ELF64
#define SG_DESC_INIT(id, p_type, p_flags, sg_name, sg_flags) \
{ id, { p_type, p_flags, 0, 0, 0, 0, 0, 0}, \
sg_name, 0, 0, NULL, NULL, sg_flags, NULL, 0, NULL}
#else
#define SG_DESC_INIT(id, p_type, p_flags, sg_name, sg_flags) \
{ id, { p_type, 0, 0, 0, 0, 0, p_flags, 0}, \
sg_name, 0, 0, NULL, NULL, sg_flags, NULL, 0, NULL}
#endif
static const Sg_desc sg_desc[LD_NUM] = {
SG_DESC_INIT(LD_PHDR, PT_PHDR, PF_R + PF_X, MSG_ORIG(MSG_ENT_PHDR),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_INTERP, PT_INTERP, PF_R, MSG_ORIG(MSG_ENT_INTERP),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_SUNWCAP, PT_SUNWCAP, PF_R, MSG_ORIG(MSG_ENT_SUNWCAP),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_TEXT, PT_LOAD, PF_R + PF_X, MSG_ORIG(MSG_ENT_TEXT),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_DATA, PT_LOAD, 0, MSG_ORIG(MSG_ENT_DATA),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_BSS, PT_LOAD, 0, MSG_ORIG(MSG_ENT_BSS),
(FLG_SG_TYPE | FLG_SG_FLAGS | FLG_SG_DISABLED)),
#if defined(_ELF64)
/* (amd64-only) */
SG_DESC_INIT(LD_LRODATA, PT_LOAD, PF_R, MSG_ORIG(MSG_ENT_LRODATA),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
/* (amd64-only) */
SG_DESC_INIT(LD_LDATA, PT_LOAD, 0, MSG_ORIG(MSG_ENT_LDATA),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
#endif
SG_DESC_INIT(LD_DYN, PT_DYNAMIC, 0, MSG_ORIG(MSG_ENT_DYNAMIC),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_DTRACE, PT_SUNWDTRACE, 0, MSG_ORIG(MSG_ENT_DTRACE),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_TLS, PT_TLS, PF_R, MSG_ORIG(MSG_ENT_TLS),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_UNWIND, PT_SUNW_UNWIND, PF_R, MSG_ORIG(MSG_ENT_UNWIND),
(FLG_SG_TYPE | FLG_SG_FLAGS)),
SG_DESC_INIT(LD_NOTE, PT_NOTE, 0, MSG_ORIG(MSG_ENT_NOTE), FLG_SG_TYPE),
SG_DESC_INIT(LD_EXTRA, PT_NULL, 0, MSG_ORIG(MSG_STR_EMPTY), FLG_SG_TYPE)
};
/*
* The processing of input files by the link-editor involves matching the
* files sections to an `entrance descriptor definition'. The entrance
* criteria can be modified further using a mapfile. Each entrance criteria
* is associated with a segment descriptor, thus a mapping of input sections
* to output segments is maintained.
*
* Note the trick used for the ec_segment field, which is supposed to be a
* pointer to a segment descriptor. We initialize this with the index of the
* descriptor, and then turn it into an actual pointer at runtime, once memory
* has been allocated and the templates copied.
*/
static const Ent_desc ent_desc[] = {
{NULL, NULL, SHT_NOTE, 0, 0,
(Sg_desc *)LD_NOTE, 0, FALSE},
#if defined(_ELF64) /* (amd64-only) */
{NULL, MSG_ORIG(MSG_SCN_LRODATA), NULL,
SHF_ALLOC + SHF_AMD64_LARGE, SHF_ALLOC + SHF_AMD64_LARGE,
(Sg_desc *)LD_LRODATA, 0, FALSE},
#endif
{NULL, NULL, NULL,
SHF_ALLOC + SHF_WRITE, SHF_ALLOC,
(Sg_desc *)LD_TEXT, 0, FALSE},
{NULL, NULL, SHT_NOBITS,
SHF_ALLOC + SHF_WRITE, SHF_ALLOC + SHF_WRITE,
(Sg_desc *)LD_BSS, 0, FALSE},
#if defined(_ELF64) /* (amd64-only) */
{NULL, NULL, SHT_NOBITS,
SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE,
SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE,
(Sg_desc *)LD_DATA, 0, FALSE},
{NULL, NULL, NULL,
SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE,
SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE,
(Sg_desc *)LD_LDATA, 0, FALSE},
#endif
{NULL, NULL, NULL,
SHF_ALLOC + SHF_WRITE, SHF_ALLOC + SHF_WRITE,
(Sg_desc *)LD_DATA, 0, FALSE},
{NULL, NULL, 0, 0, 0,
(Sg_desc *)LD_EXTRA, 0, FALSE}
};
/*
* Initialize new entrance and segment descriptors and add them as lists to
* the output file descriptor.
*/
uintptr_t
ld_ent_setup(Ofl_desc *ofl, Xword segalign)
{
const Ent_desc *oenp;
Sg_desc *sgp;
size_t idx;
/*
* Initialize the elf library.
*/
if (elf_version(EV_CURRENT) == EV_NONE) {
eprintf(ofl->ofl_lml, ERR_FATAL, MSG_INTL(MSG_ELF_LIBELF),
EV_CURRENT);
return (S_ERROR);
}
/*
* Initialize internal Global Symbol Table AVL tree
*/
avl_create(&ofl->ofl_symavl, &ld_sym_avl_comp, sizeof (Sym_avlnode),
SGSOFFSETOF(Sym_avlnode, sav_node));
/*
* Allocate and initialize writable copies of both the entrance and
* segment descriptors.
*
* Note that on non-amd64 targets, this allocates a few more
* elements than are needed. For now, we are willing to overallocate
* a small amount to simplify the code.
*/
if ((sgp = libld_malloc(sizeof (sg_desc))) == NULL)
return (S_ERROR);
(void) memcpy(sgp, sg_desc, sizeof (sg_desc));
/*
* The data segment permissions can differ:
*
* - Architecural/ABI per-platform differences
* - Whether the object is built statically or dynamically
*
* Those segments so affected have their program header flags
* set here at runtime, rather than in the sg_desc templates above.
*/
sgp[LD_DATA].sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
sgp[LD_BSS].sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
sgp[LD_DYN].sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
sgp[LD_DTRACE].sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
#if defined(_ELF64)
sgp[LD_LDATA].sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
sgp[LD_DTRACE].sg_phdr.p_flags |= PF_X;
#endif
if ((ofl->ofl_flags & FLG_OF_DYNAMIC) == 0)
sgp[LD_DATA].sg_phdr.p_flags |= PF_X;
/*
* Traverse the new entrance descriptor list converting the segment
* pointer entries to the absolute address within the new segment
* descriptor list. Add each entrance descriptor to the output file
* list.
*/
for (idx = 0, oenp = ent_desc;
idx < (sizeof (ent_desc) / sizeof (ent_desc[0])); idx++, oenp++) {
Ent_desc *nenp;
#if defined(_ELF64)
/* Don't use the amd64 entry conditions for non-amd64 targets */
if ((oenp->ec_attrmask & SHF_AMD64_LARGE) &&
(ld_targ.t_m.m_mach != EM_AMD64))
continue;
#endif
if ((nenp = alist_append(&(ofl->ofl_ents), oenp,
sizeof (Ent_desc), AL_CNT_OFL_ENTRANCE)) == NULL)
return (S_ERROR);
nenp->ec_segment = &sgp[(long)oenp->ec_segment];
}
/*
* Traverse the new segment descriptor list adding each entry to the
* segment descriptor list. For each loadable segment initialize
* a default alignment (ld(1) and ld.so.1 initialize this differently).
*/
for (idx = 0; idx < LD_NUM; idx++, sgp++) {
Phdr *phdr = &(sgp->sg_phdr);
#if defined(_ELF64)
/* Ignore amd64 segment templates for non-amd64 targets */
switch (idx) {
case LD_LRODATA:
case LD_LDATA:
if ((ld_targ.t_m.m_mach != EM_AMD64))
continue;
}
#endif
if ((aplist_append(&ofl->ofl_segs, sgp,
AL_CNT_SEGMENTS)) == NULL)
return (S_ERROR);
if (phdr->p_type == PT_LOAD)
phdr->p_align = segalign;
}
return (1);
}