8322 nl: misleading-indentation

[unleashed/tickless.git] / usr / src / cmd / sgs / libld / common / entry.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 (c) 1988 AT&T
 *        All Rights Reserved
 *
 * Copyright (c) 1991, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#define ELF_TARGET_AMD64

#include        <stdio.h>
#include        <memory.h>
#include        <debug.h>
#include        "msg.h"
#include        "_libld.h"

/*
 * The link-editor uses a segment descriptor list to describe the program
 * headers, and related 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.
 *
 * 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.
 *
 * If a given program header can be referenced via an entrance criteria
 * (i.e. can serve as a segment), then it must be given a unique sg_name.
 * Program headers that cannot be a segment (PHDR, INTERP, DYNAMIC, etc)
 * must have a NULL sg_name --- their program header type identifies them.
 */
#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, 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, NULL, sg_flags, NULL, 0, NULL}
#endif

/*
 * Predefined segment descriptors:
 *
 * The C language guarantees that a structure containing only fields of
 * identical type is indistinguishable from a simple array containing
 * the same number of items of the same type. They will have the same
 * size, alignment, and internal layout:
 *
 * -    A pointer to one is equivalent to a pointer to the other, and you
 *      can cast safely between them.
 *
 * -    You can put both into a union, and access the elements within
 *      either way (by index, or by name).
 *
 * We use this fact here to create an "array" of predefined segment
 * descriptors, assigning each one a mnemonic name that can be used to point
 * at it from a predefined entrance criteria descriptor (below). These
 * segments are positioned in the default order that will result in the
 * output object, unless a mapfile alters things.
 */
typedef struct {
        Sg_desc psg_phdr;
        Sg_desc psg_interp;
        Sg_desc psg_sunwcap;
        Sg_desc psg_text;
        Sg_desc psg_data;
        Sg_desc psg_bss;
#if     defined(_ELF64)
        Sg_desc psg_lrodata;    /* (amd64-only) */
        Sg_desc psg_ldata;      /* (amd64-only) */
#endif
        Sg_desc psg_dynamic;
        Sg_desc psg_sunwdtrace;
        Sg_desc psg_tls;
        Sg_desc psg_unwind;
        Sg_desc psg_sunwstack;
        Sg_desc psg_note;
        Sg_desc psg_extra;
} predef_seg_t;

static const size_t predef_seg_nelts =
        (sizeof (predef_seg_t) / sizeof (Sg_desc));

static predef_seg_t sg_desc = {
        /* psg_phdr */
        SG_DESC_INIT(SGID_PHDR, PT_PHDR, PF_R + PF_X, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_interp */
        SG_DESC_INIT(SGID_INTERP, PT_INTERP, PF_R, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_sunwcap */
        SG_DESC_INIT(SGID_SUNWCAP, PT_SUNWCAP, PF_R, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_text */
        SG_DESC_INIT(SGID_TEXT, PT_LOAD, PF_R + PF_X, MSG_ORIG(MSG_ENT_TEXT),
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_data */
        SG_DESC_INIT(SGID_DATA, PT_LOAD, 0, MSG_ORIG(MSG_ENT_DATA),
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_bss */
        SG_DESC_INIT(SGID_BSS, PT_LOAD, 0, MSG_ORIG(MSG_ENT_BSS),
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS | FLG_SG_DISABLED)),

#if     defined(_ELF64)
        /* psg_lrodata (amd64-only ) */
        SG_DESC_INIT(SGID_LRODATA, PT_LOAD, PF_R, MSG_ORIG(MSG_ENT_LRODATA),
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_ldata (amd64-only ) */
        SG_DESC_INIT(SGID_LDATA, PT_LOAD, 0, MSG_ORIG(MSG_ENT_LDATA),
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),
#endif
        /* psg_dynamic */
        SG_DESC_INIT(SGID_DYN, PT_DYNAMIC, 0, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_sunwdtrace */
        SG_DESC_INIT(SGID_DTRACE, PT_SUNWDTRACE, 0, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_tls */
        SG_DESC_INIT(SGID_TLS, PT_TLS, PF_R, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_unwind */
        SG_DESC_INIT(SGID_UNWIND, PT_SUNW_UNWIND, PF_R, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS)),

        /* psg_sunwstack */
        SG_DESC_INIT(SGID_SUNWSTACK, PT_SUNWSTACK, 0, NULL,
            (FLG_SG_P_TYPE | FLG_SG_P_FLAGS | FLG_SG_DISABLED)),

        /* psg_note */
        SG_DESC_INIT(SGID_NOTE, PT_NOTE, 0, MSG_ORIG(MSG_ENT_NOTE),
            FLG_SG_P_TYPE),

        /*
         * psg_extra
         *
         * This segment is referenced by the final entrance criteria descriptor
         * to catch any segment not otherwise placed. It cannot be disabled
         * via a mapfile.
         */
        SG_DESC_INIT(SGID_EXTRA, PT_NULL, 0, MSG_ORIG(MSG_ENT_EXTRA),
            (FLG_SG_P_TYPE | FLG_SG_NODISABLE))
};
#undef SG_DESC_INIT

/*
 * The processing of input files by the link-editor involves matching the
 * input file sections against an ordered list of entrance criteria
 * descriptors. The following template defines the built in entrance criteria
 * list. This list can be augmented using a mapfile. Each entrance criteria
 * is associated with a segment descriptor, providing the means for mapping
 * input sections to output segments.
 *
 * As with the segment descriptors, the EC_DESC_INIT macro is used
 * to reduce boilerplate clutter.
 */
#define EC_DESC_INIT(ec_is_name, ec_type, ec_attrmask, ec_attrbits, \
    _seg_field, ec_flags) \
        { NULL, NULL, ec_is_name, ec_type, ec_attrmask, ec_attrbits, \
            &sg_desc.psg_ ## _seg_field, 0, FLG_EC_BUILTIN | ec_flags }

static const Ent_desc   ent_desc[] = {
        EC_DESC_INIT(NULL, SHT_NOTE, 0, 0, note, 0),

#if     defined(_ELF64)         /* (amd64-only) */
        EC_DESC_INIT(NULL, 0, SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE,
            SHF_ALLOC + SHF_AMD64_LARGE, lrodata, 0),
#endif
        EC_DESC_INIT(NULL, 0, SHF_ALLOC + SHF_WRITE, SHF_ALLOC, text, 0),

        /*
         * Explicitly assign the .tdata section to bss.  The design of TLS
         * provides for initialized data being assigned to a .tdata section,
         * and uninitialized data being assigned to a .tbss section.  These
         * sections should be laid out adjacent to each other, with little or
         * no gap between them.  A PT_TLS program header is created that
         * defines the address range of the two sections.  This header is
         * passed to libc to instantiate the appropriate thread allocation.
         *
         * By default a separate bss segment is disabled, however users can
         * trigger the creation of a bss segment with a mapfile.  By default,
         * all bss sections are assigned to the data segment, and the section
         * identifiers of .tdata and .tbss ensure that these two sections are
         * adjacent to each other.
         *
         * However, if a bss segment is enabled, the adjacency of the .tdata
         * and .tbss sections can only be retained by having an explicit .tdata
         * entrance criteria.
         */
        EC_DESC_INIT(MSG_ORIG(MSG_SCN_TDATA), 0, SHF_ALLOC + SHF_WRITE,
            SHF_ALLOC + SHF_WRITE, bss, 0),

        EC_DESC_INIT(NULL, SHT_NOBITS, SHF_ALLOC + SHF_WRITE,
            SHF_ALLOC + SHF_WRITE, bss, 0),

#if     defined(_ELF64)         /* (amd64-only) */
        EC_DESC_INIT(NULL, SHT_NOBITS, SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE,
            SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE, data, 0),

        EC_DESC_INIT(NULL, 0, SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE,
            SHF_ALLOC + SHF_WRITE + SHF_AMD64_LARGE, ldata, 0),
#endif
        EC_DESC_INIT(NULL, 0, SHF_ALLOC + SHF_WRITE, SHF_ALLOC + SHF_WRITE,
            data, 0),

        /*
         * Final catchall rule sends remaining sections to "extra"
         * NULL segment, which has been tagged as FLG_SG_NODISABLE,
         * and which will therefore always accept them.
         */
        EC_DESC_INIT(NULL, 0, 0, 0, extra, FLG_EC_CATCHALL)
};
#undef EC_DESC_INIT

/*
 * AVL comparison function for Sg_desc items in ofl_segs_avl.
 *
 * entry:
 *      n1, n2 - pointers to nodes to be compared
 *
 * exit:
 *      Returns -1 if (n1 < n2), 0 if they are equal, and 1 if (n1 > n2)
 */
static int
ofl_segs_avl_cmp(const void *n1, const void *n2)
{
        int             rc;

        rc = strcmp(((Sg_desc *)n1)->sg_name, ((Sg_desc *)n2)->sg_name);

        if (rc > 0)
                return (1);
        if (rc < 0)
                return (-1);
        return (0);
}

/*
 * AVL comparison function for Ent_desc items in ofl_ents_avl.
 *
 * entry:
 *      n1, n2 - pointers to nodes to be compared
 *
 * exit:
 *      Returns -1 if (n1 < n2), 0 if they are equal, and 1 if (n1 > n2)
 */
static int
ofl_ents_avl_cmp(const void *n1, const void *n2)
{
        int             rc;

        /*
         * There are entrance criteria nodes with NULL pointer names,
         * but they are never entered into the AVL tree. Hence, we can
         * assume that both nodes have names.
         */
        rc = strcmp(((Ent_desc *)n1)->ec_name, ((Ent_desc *)n2)->ec_name);

        if (rc > 0)
                return (1);
        if (rc < 0)
                return (-1);
        return (0);
}

/*
 * Lookup a segment descriptor by name.
 *
 * entry:
 *      ofl - Output descriptor
 *      name - Name of desired segment
 *
 * exit:
 *      On success, returns pointer to descriptor. On failure, returns NULL.
 */
Sg_desc *
ld_seg_lookup(Ofl_desc *ofl, const char *name, avl_index_t *where)
{
        Sg_desc         sg;

        sg.sg_name = name;
        return (avl_find(&ofl->ofl_segs_avl, &sg, where));
}


/*
 * Look up an entrance criteria record by name
 *
 * entry:
 *      mf - Mapfile descriptor
 *      name - Name of entrance criteria to locate
 *
 * exit:
 *      On success, a pointer to the entrace criteria record is
 *      returned. On failure, NULL is returned.
 *
 * note:
 *      Entrance criteria are not required to have names. Only
 *      named entrance criteria can be looked up via this method.
 */
Ent_desc *
ld_ent_lookup(Ofl_desc *ofl, const char *name, avl_index_t *where)
{
        Ent_desc        en;

        en.ec_name = name;
        return (avl_find(&ofl->ofl_ents_avl, &en, where));
}

/*
 * 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)
{
        Ent_desc        *enp;
        predef_seg_t    *psegs;
        Sg_desc         *sgp;
        size_t          idx;

        /*
         * Initialize the elf library.
         */
        if (elf_version(EV_CURRENT) == EV_NONE) {
                ld_eprintf(ofl, 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));

        /* Initialize segment AVL tree */
        avl_create(&ofl->ofl_segs_avl, ofl_segs_avl_cmp,
            sizeof (Sg_desc), SGSOFFSETOF(Sg_desc, sg_avlnode));

        /* Initialize entrance criteria AVL tree */
        avl_create(&ofl->ofl_ents_avl, ofl_ents_avl_cmp, sizeof (Ent_desc),
            SGSOFFSETOF(Ent_desc, ec_avlnode));


        /*
         * 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 ((psegs = libld_malloc(sizeof (sg_desc))) == NULL)
                return (S_ERROR);
        (void) memcpy(psegs, &sg_desc, sizeof (sg_desc));
        sgp = (Sg_desc *) psegs;

        /*
         * The data segment and stack permissions can differ:
         *
         *      - Architectural/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.
         */
        psegs->psg_data.sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
        psegs->psg_bss.sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
        psegs->psg_dynamic.sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
        psegs->psg_sunwdtrace.sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
#if     defined(_ELF64)
        psegs->psg_ldata.sg_phdr.p_flags = ld_targ.t_m.m_dataseg_perm;
        psegs->psg_sunwdtrace.sg_phdr.p_flags |= PF_X;
#endif
        psegs->psg_sunwstack.sg_phdr.p_flags = ld_targ.t_m.m_stack_perm;
        if ((ofl->ofl_flags & FLG_OF_DYNAMIC) == 0)
                psegs->psg_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.
         */
        if ((enp = libld_malloc(sizeof (ent_desc))) == NULL)
                return (S_ERROR);
        (void) memcpy(enp, ent_desc, sizeof (ent_desc));
        for (idx = 0; idx < (sizeof (ent_desc) / sizeof (ent_desc[0])); idx++,
            enp++) {

#if     defined(_ELF64)
                /* Don't use the amd64 entry conditions for non-amd64 targets */
                if ((enp->ec_attrmask & SHF_AMD64_LARGE) &&
                    (ld_targ.t_m.m_mach != EM_AMD64))
                        continue;
#endif
                if (aplist_append(&ofl->ofl_ents, enp,
                    AL_CNT_OFL_ENTRANCE) == NULL)
                        return (S_ERROR);

                /*
                 * The segment pointer is currently pointing at a template
                 * segment descriptor in sg_desc. Compute its array index,
                 * and then use that index to compute the address of the
                 * corresponding descriptor in the writable copy.
                 */
                enp->ec_segment =
                    &sgp[(enp->ec_segment - (Sg_desc *) &sg_desc)];
        }

        /*
         * Add each segment descriptor to the segment descriptor list. The
         * ones with non-NULL sg_name are also entered into the AVL tree.
         * For each loadable segment initialize a default alignment. Note
         * that ld(1) and ld.so.1 initialize this differently.
         */
        for (idx = 0; idx < predef_seg_nelts; idx++, sgp++) {
                Phdr    *phdr = &(sgp->sg_phdr);

#if     defined(_ELF64)
                /* Ignore amd64 segment templates for non-amd64 targets */
                switch (sgp->sg_id) {
                case SGID_LRODATA:
                case SGID_LDATA:
                        if ((ld_targ.t_m.m_mach != EM_AMD64))
                                continue;
                }
#endif
                if (phdr->p_type == PT_LOAD)
                        phdr->p_align = segalign;

                if ((aplist_append(&ofl->ofl_segs, sgp,
                    AL_CNT_SEGMENTS)) == NULL)
                        return (S_ERROR);

#ifdef NDEBUG                   /* assert() is enabled */
                /*
                 * Enforce the segment name rule: Any segment that can
                 * be referenced by an entrance descriptor must have
                 * a name. Any segment that cannot, must have a NULL
                 * name pointer.
                 */
                switch (phdr->p_type) {
                case PT_LOAD:
                case PT_NOTE:
                case PT_NULL:
                        assert(sgp->sg_name != NULL);
                        break;
                default:
                        assert(sgp->sg_name == NULL);
                        break;
                }
#endif

                /*
                 * Add named segment descriptors to the AVL tree to
                 * provide O(logN) lookups.
                 */
                if (sgp->sg_name != NULL)
                        avl_add(&ofl->ofl_segs_avl, sgp);
        }

        return (1);
}