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[netbsd-mini2440.git] / libexec / ld.elf_so / arch / hppa / hppa_reloc.c

/*      $NetBSD: hppa_reloc.c,v 1.29 2009/08/29 13:46:54 jmmv Exp $     */

/*-
 * Copyright (c) 2002, 2004 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Fredette and Nick Hudson.
 *
 * 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 NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``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 FOUNDATION OR CONTRIBUTORS
 * 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/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: hppa_reloc.c,v 1.29 2009/08/29 13:46:54 jmmv Exp $");
#endif /* not lint */

#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/queue.h>

#include <string.h>

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

#ifdef RTLD_DEBUG_HPPA
#define hdbg(x)         xprintf x
#else
#define hdbg(x)         /* nothing */
#endif

caddr_t _rtld_bind(const Obj_Entry *, const Elf_Addr);
void _rtld_bind_start(void);
void __rtld_setup_hppa_pltgot(const Obj_Entry *, Elf_Addr *);

/*
 * It is possible for the compiler to emit relocations for unaligned data.
 * We handle this situation with these inlines.
 */
#define RELOC_ALIGNED_P(x) \
        (((uintptr_t)(x) & (sizeof(void *) - 1)) == 0)

static inline Elf_Addr
load_ptr(void *where)
{
        if (__predict_true(RELOC_ALIGNED_P(where)))
                return *(Elf_Addr *)where;
        else {
                Elf_Addr res;

                (void)memcpy(&res, where, sizeof(res));
                return res;
        }
}

static inline void
store_ptr(void *where, Elf_Addr val)
{
        if (__predict_true(RELOC_ALIGNED_P(where)))
                *(Elf_Addr *)where = val;
        else
                (void)memcpy(where, &val, sizeof(val));
}

/*
 * In the runtime architecture (ABI), PLABEL function 
 * pointers are distinguished from normal function 
 * pointers by having the next-least-significant bit
 * set.  (This bit is referred to as the L field in
 * HP documentation).  The $$dyncall millicode is
 * aware of this.
 */
#define RTLD_MAKE_PLABEL(plabel)        (((Elf_Addr)(plabel)) | (1 << 1))
#define RTLD_IS_PLABEL(addr)            (((Elf_Addr)(addr)) & (1 << 1))
#define RTLD_GET_PLABEL(addr)   ((hppa_plabel *) (((Elf_Addr)addr) & ~3))

/*
 * This is the PLABEL structure.  The function PC and
 * shared linkage members must come first, as they are
 * the actual PLABEL.
 */
typedef struct _hppa_plabel {
        Elf_Addr        hppa_plabel_pc;
        Elf_Addr        hppa_plabel_sl;
        SLIST_ENTRY(_hppa_plabel)       hppa_plabel_next;
} hppa_plabel;

/*
 * For now allocated PLABEL structures are tracked on a 
 * singly linked list.  This maybe should be revisited.
 */
static SLIST_HEAD(hppa_plabel_head, _hppa_plabel) hppa_plabel_list
    = SLIST_HEAD_INITIALIZER(hppa_plabel_list);

/*
 * Because I'm hesitant to use NEW while relocating self,
 * this is a small pool of preallocated PLABELs.
 */
#define HPPA_PLABEL_PRE (14)
static hppa_plabel hppa_plabel_pre[HPPA_PLABEL_PRE];
static int hppa_plabel_pre_next = 0;

void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
int _rtld_relocate_plt_objects(const Obj_Entry *);
static inline int _rtld_relocate_plt_object(const Obj_Entry *,
    const Elf_Rela *, Elf_Addr *);

/*
 * This bootstraps the dynamic linker by relocating its GOT.
 * On the hppa, unlike on other architectures, static strings
 * are found through the GOT.  Static strings are essential
 * for RTLD_DEBUG, and I suspect they're used early even when 
 * !defined(RTLD_DEBUG), making relocating the GOT essential.
 *
 * It gets worse.  Relocating the GOT doesn't mean just walking
 * it and adding the relocbase to all of the entries.  You must
 * find and use the GOT relocations, since those RELA relocations 
 * have the necessary addends - the GOT comes initialized as 
 * zeroes.
 */
void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
        const Elf_Rela  *relafirst, *rela, *relalim;
        Elf_Addr        relasz;
        void            *where;
        Elf_Addr        *pltgot;
        const Elf_Rela  *plabel_relocs[HPPA_PLABEL_PRE];
        int             nplabel_relocs = 0;
        int             i;
        const Elf_Sym   *symtab, *sym;
        unsigned long   symnum;
        hppa_plabel     *plabel;

        /*
         * Process the DYNAMIC section, looking for the non-PLT relocations.
         */ 
        relafirst = NULL;
        relasz = 0;
        symtab = NULL;
        pltgot = NULL;
        for (; dynp->d_tag != DT_NULL; ++dynp) {
                switch (dynp->d_tag) {

                case DT_RELA:
                        relafirst = (const Elf_Rela *)
                            (relocbase + dynp->d_un.d_ptr);
                        break;

                case DT_RELASZ:
                        relasz = dynp->d_un.d_val;
                        break;

                case DT_SYMTAB:
                        symtab = (const Elf_Sym *)
                            (relocbase + dynp->d_un.d_ptr);
                        break;

                case DT_PLTGOT:
                        pltgot = (Elf_Addr *)
                            (relocbase + dynp->d_un.d_ptr);
                        break;
                }
        }
        relalim = (const Elf_Rela *)((const char *)relafirst + relasz);

        for (rela = relafirst; rela < relalim; rela++) {
                symnum = ELF_R_SYM(rela->r_info);
                where = (void *)(relocbase + rela->r_offset);

                switch (ELF_R_TYPE(rela->r_info)) {
                case R_TYPE(DIR32):
                        if (symnum == 0)
                                store_ptr(where, 
                                    relocbase + rela->r_addend);
                        else {
                                sym = symtab + symnum;
                                store_ptr(where, 
                                    relocbase + rela->r_addend + sym->st_value);
                        }
                        break;

                case R_TYPE(PLABEL32):
                        /*
                         * PLABEL32 relocation processing is done in two phases
                         *
                         *  i) local function relocations (symbol number == 0)
                         *     can be resolved immediately.
                         *
                         * ii) external function relocations are deferred until
                         *     we finish all other relocations so that global
                         *     data isn't accessed until all other non-PLT
                         *     relocations have been done.
                         */
                        if (symnum == 0)
                                *((Elf_Addr *)where) = 
                                    relocbase + rela->r_addend;
                        else
                                plabel_relocs[nplabel_relocs++] = rela;
                        break;

                default:
                        break;
                }
        }

        assert(nplabel_relocs < HPPA_PLABEL_PRE);
        for (i = 0; i < nplabel_relocs; i++) {
                rela = plabel_relocs[i];
                where = (void *)(relocbase + rela->r_offset);
                sym = symtab + ELF_R_SYM(rela->r_info);
                
                plabel = &hppa_plabel_pre[hppa_plabel_pre_next++];

                plabel->hppa_plabel_pc = (Elf_Addr)
                    (relocbase + sym->st_value + rela->r_addend);
                plabel->hppa_plabel_sl = (Elf_Addr)pltgot;

                SLIST_INSERT_HEAD(&hppa_plabel_list, plabel, hppa_plabel_next);
                *((Elf_Addr *)where) = (Elf_Addr)(RTLD_MAKE_PLABEL(plabel));
        }
        
#if defined(RTLD_DEBUG_HPPA)
        for (rela = relafirst; rela < relalim; rela++) {
                where = (void *)(relocbase + rela->r_offset);

                switch (ELF_R_TYPE(rela->r_info)) {
                case R_TYPE(DIR32):
                        hdbg(("DIR32 rela @%p(%p) -> %p(%p)\n",
                            (void *)rela->r_offset,
                            (void *)where,
                            (void *)rela->r_addend,
                            (void *)*((Elf_Addr *)where) ));
                        break;

                case R_TYPE(PLABEL32):
                        symnum = ELF_R_SYM(rela->r_info);
                        if (symnum == 0) {
                                hdbg(("PLABEL rela @%p(%p) -> %p(%p)\n",
                                    (void *)rela->r_offset,
                                    (void *)where,
                                    (void *)rela->r_addend,
                                    (void *)*((Elf_Addr *)where) ));
                        } else {
                                sym = symtab + symnum;

                                hdbg(("PLABEL32 rela @%p(%p), symnum=%ld(%p) -> %p(%p)\n",
                                    (void *)rela->r_offset,
                                    (void *)where,
                                    symnum,
                                    (void *)sym->st_value,
                                    (void *)rela->r_addend,
                                    (void *)*((Elf_Addr *)where) ));
                        }
                        break;
                default:
                        hdbg(("rela XXX reloc\n"));
                        break;
                }
        }
#endif /* RTLD_DEBUG_HPPA */
}

/*
 * This allocates a PLABEL.  If called with a non-NULL def, the 
 * plabel is for the function associated with that definition
 * in the defining object defobj, plus the given addend.  If 
 * called with a NULL def, the plabel is for the function at
 * the (unrelocated) address in addend in the object defobj.
 */
Elf_Addr
_rtld_function_descriptor_alloc(const Obj_Entry *defobj, const Elf_Sym *def,
    Elf_Addr addend)
{
        Elf_Addr        func_pc, func_sl;
        hppa_plabel     *plabel;

        if (def != NULL) {
        
                /*
                 * We assume that symbols of type STT_NOTYPE
                 * are undefined.  Return NULL for these.
                 */
                if (ELF_ST_TYPE(def->st_info) == STT_NOTYPE)
                        return (Elf_Addr)NULL;

                /* Otherwise assert that this symbol must be a function. */
                assert(ELF_ST_TYPE(def->st_info) == STT_FUNC);

                func_pc = (Elf_Addr)(defobj->relocbase + def->st_value + 
                    addend);
        } else
                func_pc = (Elf_Addr)(defobj->relocbase + addend);

        /*
         * Search the existing PLABELs for one matching
         * this function.  If there is one, return it.
         */
        func_sl = (Elf_Addr)(defobj->pltgot);
        SLIST_FOREACH(plabel, &hppa_plabel_list, hppa_plabel_next)
                if (plabel->hppa_plabel_pc == func_pc &&
                    plabel->hppa_plabel_sl == func_sl)
                        return RTLD_MAKE_PLABEL(plabel);

        /*
         * Once we've used up the preallocated set, we start
         * using NEW to allocate plabels.
         */
        if (hppa_plabel_pre_next < HPPA_PLABEL_PRE)
                plabel = &hppa_plabel_pre[hppa_plabel_pre_next++];
        else {
                plabel = NEW(hppa_plabel);
                if (plabel == NULL)
                        return (Elf_Addr)-1;
        }

        /* Fill the new entry and insert it on the list. */
        plabel->hppa_plabel_pc = func_pc;
        plabel->hppa_plabel_sl = func_sl;
        SLIST_INSERT_HEAD(&hppa_plabel_list, plabel, hppa_plabel_next);

        return RTLD_MAKE_PLABEL(plabel);
}

/*
 * If a pointer is a PLABEL, this unwraps it.
 */
const void *
_rtld_function_descriptor_function(const void *addr)
{
        return (RTLD_IS_PLABEL(addr) ? 
            (const void *) RTLD_GET_PLABEL(addr)->hppa_plabel_pc :
            addr);
}

/* This sets up an object's GOT. */
void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
        __rtld_setup_hppa_pltgot(obj, obj->pltgot);
}

int
_rtld_relocate_nonplt_objects(const Obj_Entry *obj)
{
        const Elf_Rela *rela;

        for (rela = obj->rela; rela < obj->relalim; rela++) {
                Elf_Addr        *where;
                const Elf_Sym   *def;
                const Obj_Entry *defobj;
                Elf_Addr         tmp;
                unsigned long    symnum;

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

                switch (ELF_R_TYPE(rela->r_info)) {
                case R_TYPE(NONE):
                        break;

                case R_TYPE(DIR32):
                        if (symnum) {
                                /*
                                 * This is either a DIR32 against a symbol
                                 * (def->st_name != 0), or against a local
                                 * section (def->st_name == 0).
                                 */
                                def = obj->symtab + symnum;
                                defobj = obj;
                                if (def->st_name != 0)
                                        def = _rtld_find_symdef(symnum, obj,
                                            &defobj, false);
                                if (def == NULL)
                                        return -1;

                                tmp = (Elf_Addr)(defobj->relocbase +
                                    def->st_value + rela->r_addend);

                                if (load_ptr(where) != tmp)
                                        store_ptr(where, tmp);
                                rdbg(("DIR32 %s in %s --> %p in %s",
                                    obj->strtab + obj->symtab[symnum].st_name,
                                    obj->path, (void *)load_ptr(where), defobj->path));
                        } else {
                                tmp = (Elf_Addr)(obj->relocbase +
                                    rela->r_addend);

                                if (load_ptr(where) != tmp)
                                        store_ptr(where, tmp);
                                rdbg(("DIR32 in %s --> %p", obj->path,
                                            (void *)load_ptr(where)));
                        }
                        break;

                case R_TYPE(PLABEL32):
                        if (symnum) {
                                def = _rtld_find_symdef(symnum, obj, &defobj,
                                    false);
                                if (def == NULL)
                                        return -1;

                                tmp = _rtld_function_descriptor_alloc(defobj,
                                    def, rela->r_addend);
                                if (tmp == (Elf_Addr)-1)
                                        return -1;

                                if (*where != tmp)
                                        *where = tmp;
                                rdbg(("PLABEL32 %s in %s --> %p in %s",
                                    obj->strtab + obj->symtab[symnum].st_name,
                                    obj->path, (void *)*where, defobj->path));
                        } else {
                                /*
                                 * This is a PLABEL for a static function, and
                                 * the dynamic linker has both allocated a PLT
                                 * entry for this function and told us where it
                                 * is.  We can safely use the PLT entry as the
                                 * PLABEL because there should be no other
                                 * PLABEL reloc referencing this function.
                                 * This object should also have an IPLT
                                 * relocation to initialize the PLT entry.
                                 *
                                 * The dynamic linker should also have ensured
                                 * that the addend has the
                                 * next-least-significant bit set; the
                                 * $$dyncall millicode uses this to distinguish
                                 * a PLABEL pointer from a plain function
                                 * pointer.
                                 */
                                tmp = (Elf_Addr)
                                    (obj->relocbase + rela->r_addend);

                                if (*where != tmp)
                                        *where = tmp;
                                rdbg(("PLABEL32 in %s --> %p", obj->path,
                                    (void *)*where));
                        }
                        break;

                case R_TYPE(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->isdynamic) {
                                _rtld_error(
                        "%s: Unexpected R_COPY relocation in shared library",
                                    obj->path);
                                return -1;
                        }
                        rdbg(("COPY (avoid in main)"));
                        break;

                default:
                        rdbg(("sym = %lu, type = %lu, offset = %p, "
                            "addend = %p, contents = %p, symbol = %s",
                            symnum, (u_long)ELF_R_TYPE(rela->r_info),
                            (void *)rela->r_offset, (void *)rela->r_addend,
                            (void *)load_ptr(where),
                            obj->strtab + obj->symtab[symnum].st_name));
                        _rtld_error("%s: Unsupported relocation type %ld "
                            "in non-PLT relocations",
                            obj->path, (u_long) ELF_R_TYPE(rela->r_info));
                        return -1;
                }
        }
        return 0;
}

int
_rtld_relocate_plt_lazy(const Obj_Entry *obj)
{
        const Elf_Rela *rela;

        for (rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
                Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                Elf_Addr func_pc, func_sl;

                assert(ELF_R_TYPE(rela->r_info) == R_TYPE(IPLT));

                /*
                 * If this is an IPLT reloc for a static function,
                 * fully resolve the PLT entry now.
                 */
                if (ELF_R_SYM(rela->r_info) == 0) {
                        func_pc = (Elf_Addr)(obj->relocbase + rela->r_addend);
                        func_sl = (Elf_Addr)(obj->pltgot);
                }

                /*
                 * Otherwise set up for lazy binding.
                 */
                else {
                        /*
                         * This function pointer points to the PLT
                         * stub added by the linker, and instead of
                         * a shared linkage value, we stash this
                         * relocation's offset.  The PLT stub has
                         * already been set up to transfer to
                         * _rtld_bind_start.
                         */
                        func_pc = ((Elf_Addr)(obj->pltgot)) - 16;
                        func_sl = (Elf_Addr)
                            ((const char *)rela - (const char *)(obj->pltrela));
                }
                rdbg(("lazy bind %s(%p) --> old=(%p,%p) new=(%p,%p)",
                    obj->path,
                    (void *)where,
                    (void *)where[0], (void *)where[1], 
                    (void *)func_pc, (void *)func_sl));

                /*
                 * Fill this PLT entry and return.
                 */
                where[0] = func_pc;
                where[1] = func_sl;
        }
        return 0;
}

static inline int
_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
{
        Elf_Word *where = (Elf_Word *)(obj->relocbase + rela->r_offset);
        const Elf_Sym *def;
        const Obj_Entry *defobj;
        Elf_Addr        func_pc, func_sl;

        assert(ELF_R_TYPE(rela->r_info) == R_TYPE(IPLT));

        if (ELF_R_SYM(rela->r_info) == 0) {
                func_pc = (Elf_Addr)(obj->relocbase + rela->r_addend);
                func_sl = (Elf_Addr)(obj->pltgot);
        } else {
                def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true);
                if (def == NULL)
                        return -1;

                func_pc = (Elf_Addr)(defobj->relocbase + def->st_value + rela->r_addend);
                func_sl = (Elf_Addr)(defobj->pltgot);

                rdbg(("bind now/fixup in %s --> old=(%p,%p) new=(%p,%p)",
                    defobj->strtab + def->st_name,
                    (void *)where[0], (void *)where[1], 
                    (void *)func_pc, (void *)func_sl));
        }
        /*
         * Fill this PLT entry and return.
         */
        if (where[0] != func_pc)
                where[0] = func_pc;
        if (where[1] != func_sl)
                where[1] = func_sl;

        if (tp)
                *tp = (Elf_Addr)where;

        return 0;
}

caddr_t
_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
{
        const Elf_Rela *rela;
        Elf_Addr new_value;
        int err;

        rela = (const Elf_Rela *)((const char *)obj->pltrela + reloff);
        
        assert(ELF_R_SYM(rela->r_info) != 0);

        err = _rtld_relocate_plt_object(obj, rela, &new_value); 
        if (err || new_value == 0)
                _rtld_die();

        return (caddr_t)new_value;
}

int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{
        const Elf_Rela *rela = obj->pltrela;
        
        for (; rela < obj->pltrelalim; rela++) {
                if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
                        return -1;
        }
        return 0;
}