/*      $NetBSD: ppc_reloc.c,v 1.10 2001/09/10 06:09:41 mycroft Exp $   */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (C) 1998   Tsubai Masanari
 * All rights reserved.
 *
 * 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.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * 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.
 */

#include <sys/param.h>
#include <sys/mman.h>
#include <sys/sysctl.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <machine/cpu.h>
#include <machine/md_var.h>

#include "debug.h"
#include "rtld.h"

#if !defined(_CALL_ELF) || _CALL_ELF == 1
struct funcdesc {
        Elf_Addr addr;
        Elf_Addr toc;
        Elf_Addr env;
};
#endif

bool
arch_digest_dynamic(struct Struct_Obj_Entry *obj, const Elf_Dyn *dynp)
{
        if (dynp->d_tag == DT_PPC64_GLINK) {
                obj->glink = (Elf_Addr)(obj->relocbase + dynp->d_un.d_ptr);
                return (true);
        }

        return (false);
}

/*
 * Process the R_PPC_COPY relocations
 */
int
do_copy_relocations(Obj_Entry *dstobj)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        /*
         * COPY relocs are invalid outside of the main program
         */
        assert(dstobj->mainprog);

        relalim = (const Elf_Rela *)((const char *) dstobj->rela +
            dstobj->relasize);
        for (rela = dstobj->rela;  rela < relalim;  rela++) {
                void *dstaddr;
                const Elf_Sym *dstsym;
                const char *name;
                size_t size;
                const void *srcaddr;
                const Elf_Sym *srcsym = NULL;
                const Obj_Entry *srcobj, *defobj;
                SymLook req;
                int res;

                if (ELF_R_TYPE(rela->r_info) != R_PPC_COPY) {
                        continue;
                }

                dstaddr = (void *)(dstobj->relocbase + rela->r_offset);
                dstsym = dstobj->symtab + ELF_R_SYM(rela->r_info);
                name = dstobj->strtab + dstsym->st_name;
                size = dstsym->st_size;
                symlook_init(&req, name);
                req.ventry = fetch_ventry(dstobj, ELF_R_SYM(rela->r_info));
                req.flags = SYMLOOK_EARLY;

                for (srcobj = globallist_next(dstobj); srcobj != NULL;
                     srcobj = globallist_next(srcobj)) {
                        res = symlook_obj(&req, srcobj);
                        if (res == 0) {
                                srcsym = req.sym_out;
                                defobj = req.defobj_out;
                                break;
                        }
                }

                if (srcobj == NULL) {
                        _rtld_error("Undefined symbol \"%s\" "
                                    " referenced from COPY"
                                    " relocation in %s", name, dstobj->path);
                        return (-1);
                }

                srcaddr = (const void *)(defobj->relocbase+srcsym->st_value);
                memcpy(dstaddr, srcaddr, size);
                dbg("copy_reloc: src=%p,dst=%p,size=%zd\n",srcaddr,dstaddr,size);
        }

        return (0);
}


/*
 * Perform early relocation of the run-time linker image
 */
void
reloc_non_plt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
        const Elf_Rela *rela = NULL, *relalim;
        Elf_Addr relasz = 0;
        Elf_Addr *where;

        /*
         * Extract the rela/relasz values from the dynamic section
         */
        for (; dynp->d_tag != DT_NULL; dynp++) {
                switch (dynp->d_tag) {
                case DT_RELA:
                        rela = (const Elf_Rela *)(relocbase+dynp->d_un.d_ptr);
                        break;
                case DT_RELASZ:
                        relasz = dynp->d_un.d_val;
                        break;
                }
        }

        /*
         * Relocate these values
         */
        relalim = (const Elf_Rela *)((const char *)rela + relasz);
        for (; rela < relalim; rela++) {
                where = (Elf_Addr *)(relocbase + rela->r_offset);
                *where = (Elf_Addr)(relocbase + rela->r_addend);
        }
}


/*
 * Relocate a non-PLT object with addend.
 */
static int
reloc_nonplt_object(Obj_Entry *obj_rtld __unused, Obj_Entry *obj,
    const Elf_Rela *rela, SymCache *cache, int flags, RtldLockState *lockstate)
{
        const Elf_Sym   *def = NULL;
        const Obj_Entry *defobj;
        Elf_Addr        *where, symval = 0;

        /*
         * First, resolve symbol for relocations which
         * reference symbols.
         */
        switch (ELF_R_TYPE(rela->r_info)) {

        case R_PPC64_UADDR64:    /* doubleword64 S + A */
        case R_PPC64_ADDR64:
        case R_PPC_GLOB_DAT:
        case R_PPC64_DTPMOD64:
        case R_PPC64_TPREL64:
        case R_PPC64_DTPREL64:
                def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
                    flags, cache, lockstate);
                if (def == NULL) {
                        return (-1);
                }
                /*
                 * If symbol is IFUNC, only perform relocation
                 * when caller allowed it by passing
                 * SYMLOOK_IFUNC flag.  Skip the relocations
                 * otherwise.
                 *
                 * Also error out in case IFUNC relocations
                 * are specified for TLS, which cannot be
                 * usefully interpreted.
                 */
                if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
                        switch (ELF_R_TYPE(rela->r_info)) {
                        case R_PPC64_UADDR64:
                        case R_PPC64_ADDR64:
                        case R_PPC_GLOB_DAT:
                                if ((flags & SYMLOOK_IFUNC) == 0) {
                                        dbg("Non-PLT reference to IFUNC found!");
                                        obj->non_plt_gnu_ifunc = true;
                                        return (0);
                                }
                                symval = (Elf_Addr)rtld_resolve_ifunc(
                                        defobj, def);
                                break;
                        default:
                                _rtld_error("%s: IFUNC for TLS reloc",
                                         obj->path);
                                return (-1);
                        }
                } else {
                        if ((flags & SYMLOOK_IFUNC) != 0)
                                return (0);
                        symval = (Elf_Addr)defobj->relocbase +
                                def->st_value;
                }
                break;
        default:
                if ((flags & SYMLOOK_IFUNC) != 0)
                        return (0);
        }

        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);

        switch (ELF_R_TYPE(rela->r_info)) {
        case R_PPC_NONE:
                break;
        case R_PPC64_UADDR64:
        case R_PPC64_ADDR64:
        case R_PPC_GLOB_DAT:
                /* Don't issue write if unnecessary; avoid COW page fault */
                if (*where != symval + rela->r_addend) {
                        *where = symval + rela->r_addend;
                }
                break;
        case R_PPC64_DTPMOD64:
                *where = (Elf_Addr) defobj->tlsindex;
                break;
        case R_PPC64_TPREL64:
                /*
                 * We lazily allocate offsets for static TLS as we
                 * see the first relocation that references the
                 * TLS block. This allows us to support (small
                 * amounts of) static TLS in dynamically loaded
                 * modules. If we run out of space, we generate an
                 * error.
                 */
                if (!defobj->tls_static) {
                        if (!allocate_tls_offset(
                                    __DECONST(Obj_Entry *, defobj))) {
                                _rtld_error("%s: No space available for static "
                                    "Thread Local Storage", obj->path);
                                return (-1);
                        }
                }

                *(Elf_Addr **)where = *where * sizeof(Elf_Addr)
                    + (Elf_Addr *)(def->st_value + rela->r_addend
                    + defobj->tlsoffset - TLS_TP_OFFSET - TLS_TCB_SIZE);
                break;
        case R_PPC64_DTPREL64:
                *where += (Elf_Addr)(def->st_value + rela->r_addend
                    - TLS_DTV_OFFSET);
                break;
        case R_PPC_RELATIVE:  /* doubleword64 B + A */
                symval = (Elf_Addr)(obj->relocbase + rela->r_addend);

                /* As above, don't issue write unnecessarily */
                if (*where != symval) {
                        *where = symval;
                }
                break;
        case R_PPC_COPY:
                /*
                 * These are deferred until all other relocations
                 * have been done.  All we do here is make sure
                 * that the COPY relocation is not in a shared
                 * library.  They are allowed only in executable
                 * files.
                 */
                if (!obj->mainprog) {
                        _rtld_error("%s: Unexpected R_COPY "
                                    " relocation in shared library",
                                    obj->path);
                        return (-1);
                }
                break;
        case R_PPC_IRELATIVE:
                /*
                 * These will be handled by reloc_iresolve().
                 */
                obj->irelative = true;
                break;
        case R_PPC_JMP_SLOT:
                /*
                 * These will be handled by the plt/jmpslot routines
                 */
                break;

        default:
                _rtld_error("%s: Unsupported relocation type %ld"
                            " in non-PLT relocations\n", obj->path,
                            ELF_R_TYPE(rela->r_info));
                return (-1);
        }
        return (0);
}


/*
 * Process non-PLT relocations
 */
int
reloc_non_plt(Obj_Entry *obj, Obj_Entry *obj_rtld, int flags,
    RtldLockState *lockstate)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;
        SymCache *cache;
        int bytes = obj->dynsymcount * sizeof(SymCache);
        int r = -1;

        /*
         * The dynamic loader may be called from a thread, we have
         * limited amounts of stack available so we cannot use alloca().
         */
        if (obj != obj_rtld) {
                cache = mmap(NULL, bytes, PROT_READ|PROT_WRITE, MAP_ANON,
                    -1, 0);
                if (cache == MAP_FAILED)
                        cache = NULL;
        } else
                cache = NULL;

        /*
         * From the SVR4 PPC ABI:
         * "The PowerPC family uses only the Elf32_Rela relocation
         *  entries with explicit addends."
         */
        relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize);
        for (rela = obj->rela; rela < relalim; rela++) {
                if (reloc_nonplt_object(obj_rtld, obj, rela, cache, flags,
                    lockstate) < 0)
                        goto done;
        }
        r = 0;
done:
        if (cache)
                munmap(cache, bytes);
        return (r);
}


/*
 * Initialise a PLT slot to the resolving trampoline
 */
static int
reloc_plt_object(Obj_Entry *obj, const Elf_Rela *rela)
{
        Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
        long reloff;

        reloff = rela - obj->pltrela;

        dbg(" reloc_plt_object: where=%p,reloff=%lx,glink=%#lx", (void *)where,
            reloff, obj->glink);

#if !defined(_CALL_ELF) || _CALL_ELF == 1
        /* Glink code is 3 instructions after the first 32k, 2 before */
        *where = (Elf_Addr)obj->glink + 32 + 
            8*((reloff < 0x8000) ? reloff : 0x8000) + 
            12*((reloff < 0x8000) ? 0 : (reloff - 0x8000));
#else
        /* 64-Bit ELF V2 ABI Specification, sec. 4.2.5.3. */
        *where = (Elf_Addr)obj->glink + 4*reloff + 32;
#endif

        return (0);
}

/*
 * Process the PLT relocations.
 */
int
reloc_plt(Obj_Entry *obj, int flags __unused, RtldLockState *lockstate __unused)
{
        const Elf_Rela *relalim;
        const Elf_Rela *rela;

        if (obj->pltrelasize != 0) {
                relalim = (const Elf_Rela *)((const char *)obj->pltrela +
                    obj->pltrelasize);
                for (rela = obj->pltrela;  rela < relalim;  rela++) {

#if defined(_CALL_ELF) && _CALL_ELF == 2
                        if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) {
                                dbg("ABI violation - found IRELATIVE in the PLT.");
                                obj->irelative = true;
                                continue;
                        }
#endif
                        /*
                         * PowerPC(64) .rela.plt is composed of an array of
                         * R_PPC_JMP_SLOT relocations. Unlike other platforms,
                         * this is the ONLY relocation type that is valid here.
                         */
                        assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);

                        if (reloc_plt_object(obj, rela) < 0) {
                                return (-1);
                        }
                }
        }

        return (0);
}

/*
 * LD_BIND_NOW was set - force relocation for all jump slots
 */
int
reloc_jmpslots(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{
        const Obj_Entry *defobj;
        const Elf_Rela *relalim;
        const Elf_Rela *rela;
        const Elf_Sym *def;
        Elf_Addr *where;
        Elf_Addr target;

        relalim = (const Elf_Rela *)((const char *)obj->pltrela +
            obj->pltrelasize);
        for (rela = obj->pltrela; rela < relalim; rela++) {
                /* This isn't actually a jump slot, ignore it. */
                if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE)
                        continue;
                assert(ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT);
                where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
                    SYMLOOK_IN_PLT | flags, NULL, lockstate);
                if (def == NULL) {
                        dbg("reloc_jmpslots: sym not found");
                        return (-1);
                }

                target = (Elf_Addr)(defobj->relocbase + def->st_value);

                if (def == &sym_zero) {
                        /* Zero undefined weak symbols */
#if !defined(_CALL_ELF) || _CALL_ELF == 1
                        bzero(where, sizeof(struct funcdesc));
#else
                        *where = 0;
#endif
                } else {
                        if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
                                /* LD_BIND_NOW, ifunc in shared lib.*/
                                obj->gnu_ifunc = true;
                                continue;
                        }
                        reloc_jmpslot(where, target, defobj, obj,
                            (const Elf_Rel *) rela);
                }
        }

        obj->jmpslots_done = true;

        return (0);
}


/*
 * Update the value of a PLT jump slot.
 */
Elf_Addr
reloc_jmpslot(Elf_Addr *wherep, Elf_Addr target, const Obj_Entry *defobj __unused,
    const Obj_Entry *obj __unused, const Elf_Rel *rel __unused)
{

        /*
         * At the PLT entry pointed at by `wherep', construct
         * a direct transfer to the now fully resolved function
         * address.
         */

#if !defined(_CALL_ELF) || _CALL_ELF == 1
        dbg(" reloc_jmpslot: where=%p, target=%p (%#lx + %#lx)",
            (void *)wherep, (void *)target, *(Elf_Addr *)target,
            (Elf_Addr)defobj->relocbase);

        if (ld_bind_not)
                goto out;

        /*
         * For the trampoline, the second two elements of the function
         * descriptor are unused, so we are fine replacing those at any time
         * with the real ones with no thread safety implications. However, we
         * need to make sure the main entry point pointer ([0]) is seen to be
         * modified *after* the second two elements. This can't be done in
         * general, since there are no barriers in the reading code, but put in
         * some isyncs to at least make it a little better.
         */
        memcpy(wherep, (void *)target, sizeof(struct funcdesc));
        wherep[2] = ((Elf_Addr *)target)[2];
        wherep[1] = ((Elf_Addr *)target)[1];
        __asm __volatile ("isync" : : : "memory");
        wherep[0] = ((Elf_Addr *)target)[0];
        __asm __volatile ("isync" : : : "memory");

        if (((struct funcdesc *)(wherep))->addr < (Elf_Addr)defobj->relocbase) {
                /*
                 * It is possible (LD_BIND_NOW) that the function
                 * descriptor we are copying has not yet been relocated.
                 * If this happens, fix it. Don't worry about threading in
                 * this case since LD_BIND_NOW makes it irrelevant.
                 */

                ((struct funcdesc *)(wherep))->addr +=
                    (Elf_Addr)defobj->relocbase;
                ((struct funcdesc *)(wherep))->toc +=
                    (Elf_Addr)defobj->relocbase;
        }
#else
        dbg(" reloc_jmpslot: where=%p, target=%p", (void *)wherep,
            (void *)target);

        assert(target >= (Elf_Addr)defobj->relocbase);

        if (ld_bind_not)
                goto out;

        if (*wherep != target)
                *wherep = target;

#endif
out:

        return (target);
}

int
reloc_iresolve(Obj_Entry *obj,
    struct Struct_RtldLockState *lockstate)
{
        /*
         * Since PLT slots on PowerPC64 are always R_PPC_JMP_SLOT,
         * R_PPC_IRELATIVE is in RELA.
         */
#if !defined(_CALL_ELF) || _CALL_ELF == 1
        (void)(obj);
        (void)(lockstate);
        /* XXX not implemented */
        return (0);
#else
        const Elf_Rela *relalim;
        const Elf_Rela *rela;
        Elf_Addr *where, target, *ptr;

        if (!obj->irelative)
                return (0);

        relalim = (const Elf_Rela *)((const char *)obj->rela + obj->relasize);
        for (rela = obj->rela;  rela < relalim;  rela++) {
                if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) {
                        ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend);
                        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);

                        lock_release(rtld_bind_lock, lockstate);
                        target = call_ifunc_resolver(ptr);
                        wlock_acquire(rtld_bind_lock, lockstate);

                        *where = target;
                }
        }
        /*
         * XXX Remove me when lld is fixed!
         * LLD currently makes illegal relocations in the PLT.
         */
        relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize);
        for (rela = obj->pltrela;  rela < relalim;  rela++) {
                if (ELF_R_TYPE(rela->r_info) == R_PPC_IRELATIVE) {
                        ptr = (Elf_Addr *)(obj->relocbase + rela->r_addend);
                        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);

                        lock_release(rtld_bind_lock, lockstate);
                        target = call_ifunc_resolver(ptr);
                        wlock_acquire(rtld_bind_lock, lockstate);

                        *where = target;
                }
        }

        obj->irelative = false;
        return (0);
#endif
}

int
reloc_gnu_ifunc(Obj_Entry *obj __unused, int flags __unused,
    struct Struct_RtldLockState *lockstate __unused)
{
#if !defined(_CALL_ELF) || _CALL_ELF == 1
        _rtld_error("reloc_gnu_ifunc(): Not implemented!");
        /* XXX not implemented */
        return (-1);
#else

        const Elf_Rela *relalim;
        const Elf_Rela *rela;
        Elf_Addr *where, target;
        const Elf_Sym *def;
        const Obj_Entry *defobj;

        if (!obj->gnu_ifunc)
                return (0);
        relalim = (const Elf_Rela *)((const char *)obj->pltrela + obj->pltrelasize);
        for (rela = obj->pltrela;  rela < relalim;  rela++) {
                if (ELF_R_TYPE(rela->r_info) == R_PPC_JMP_SLOT) {
                        where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                        def = find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj,
                            SYMLOOK_IN_PLT | flags, NULL, lockstate);
                        if (def == NULL)
                                return (-1);
                        if (ELF_ST_TYPE(def->st_info) != STT_GNU_IFUNC)
                                continue;
                        lock_release(rtld_bind_lock, lockstate);
                        target = (Elf_Addr)rtld_resolve_ifunc(defobj, def);
                        wlock_acquire(rtld_bind_lock, lockstate);
                        reloc_jmpslot(where, target, defobj, obj,
                            (const Elf_Rel *)rela);
                }
        }
        obj->gnu_ifunc = false;
        return (0);
#endif
}

int
reloc_iresolve_nonplt(Obj_Entry *obj __unused,
    struct Struct_RtldLockState *lockstate __unused)
{
        return (0);
}

void
init_pltgot(Obj_Entry *obj)
{
        Elf_Addr *pltcall;

        pltcall = obj->pltgot;

        if (pltcall == NULL) {
                return;
        }

#if defined(_CALL_ELF) && _CALL_ELF == 2
        pltcall[0] = (Elf_Addr)&_rtld_bind_start; 
        pltcall[1] = (Elf_Addr)obj;
#else
        memcpy(pltcall, _rtld_bind_start, sizeof(struct funcdesc));
        pltcall[2] = (Elf_Addr)obj;
#endif
}

/*
 * Actual values are 32 bit.
 */
u_long cpu_features;
u_long cpu_features2;

void
powerpc64_abi_variant_hook(Elf_Auxinfo** aux_info)
{
        /*
         * Since aux_info[] is easier to work with than aux, go ahead and
         * initialize cpu_features / cpu_features2.
         */
        cpu_features = -1UL;
        cpu_features2 = -1UL;
        if (aux_info[AT_HWCAP] != NULL)
                cpu_features = (uint32_t)aux_info[AT_HWCAP]->a_un.a_val;
        if (aux_info[AT_HWCAP2] != NULL)
                cpu_features2 = (uint32_t)aux_info[AT_HWCAP2]->a_un.a_val;
}

void
ifunc_init(Elf_Auxinfo *aux_info[__min_size(AT_COUNT)] __unused)
{

}

void
allocate_initial_tls(Obj_Entry *list)
{

        /*
        * Fix the size of the static TLS block by using the maximum
        * offset allocated so far and adding a bit for dynamic modules to
        * use.
        */

        tls_static_space = tls_last_offset + tls_last_size +
            ld_static_tls_extra;

        _tcb_set(allocate_tls(list, NULL, TLS_TCB_SIZE, TLS_TCB_ALIGN));
}

void*
__tls_get_addr(tls_index* ti)
{
        return (tls_get_addr_common(_tcb_get(), ti->ti_module, ti->ti_offset +
            TLS_DTV_OFFSET));
}

void
arch_fix_auxv(Elf_Auxinfo *aux, Elf_Auxinfo *aux_info[])
{
        Elf_Auxinfo *auxp;

        for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
                if (auxp->a_type == 23) /* AT_STACKPROT */
                        return;
        }

        /* Remap from old-style auxv numbers. */
        aux_info[23] = aux_info[21]; /* AT_STACKPROT */
        aux_info[21] = aux_info[19]; /* AT_PAGESIZESLEN */
        aux_info[19] = aux_info[17]; /* AT_NCPUS */
        aux_info[17] = aux_info[15]; /* AT_CANARYLEN */
        aux_info[15] = aux_info[13]; /* AT_EXECPATH */
        aux_info[13] = NULL;         /* AT_GID */

        aux_info[20] = aux_info[18]; /* AT_PAGESIZES */
        aux_info[18] = aux_info[16]; /* AT_OSRELDATE */
        aux_info[16] = aux_info[14]; /* AT_CANARY */
        aux_info[14] = NULL;         /* AT_EGID */
}