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//==========================================================================

//

//      loader.cxx

//

//      Loader class implementation

//

//==========================================================================

// ####ECOSGPLCOPYRIGHTBEGIN####                                            

// -------------------------------------------                              

// This file is part of eCos, the Embedded Configurable Operating System.   

// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.

//

// eCos is free software; you can redistribute it and/or modify it under    

// the terms of the GNU General Public License as published by the Free     

// Software Foundation; either version 2 or (at your option) any later      

// version.                                                                 

//

// eCos is distributed in the hope that it will be useful, but WITHOUT      

// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or    

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License    

// for more details.                                                        

//

// You should have received a copy of the GNU General Public License        

// along with eCos; if not, write to the Free Software Foundation, Inc.,    

// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.            

//

// As a special exception, if other files instantiate templates or use      

// macros or inline functions from this file, or you compile this file      

// and link it with other works to produce a work based on this file,       

// this file does not by itself cause the resulting work to be covered by   

// the GNU General Public License. However the source code for this file    

// must still be made available in accordance with section (3) of the GNU   

// General Public License v2.                                               

//

// This exception does not invalidate any other reasons why a work based    

// on this file might be covered by the GNU General Public License.         

// -------------------------------------------                              

// ####ECOSGPLCOPYRIGHTEND####                                              

//==========================================================================

//#####DESCRIPTIONBEGIN####

//

// Author(s):           nickg

// Contributors:        nickg

// Date:                2000-11-03

// Purpose:             Loader class implementation

// Description:         This file contains the implementation of the ELF loader

//                      classes.

//              

//              

//

//####DESCRIPTIONEND####

//

//==========================================================================

#include <pkgconf/hal.h>

#include <pkgconf/kernel.h>

#include <pkgconf/isoinfra.h>

#include <cyg/kernel/ktypes.h>          // base kernel types

#include <cyg/infra/cyg_trac.h>         // tracing macros

#include <cyg/infra/cyg_ass.h>          // assertion macros

#include <string.h>

#include <cyg/loader/loader.hxx>        // our header

#if CYGINT_ISO_MALLOC

#include <stdlib.h>                     // for malloc() etc

#endif

// ----------------------------------------------------------------------------

#ifdef CYGPKG_LIBC_STRING

#define streq( a, b ) (strcmp(a,b) == 0)

#else

static int streq( const char *s1, const char *s2 )

{

    while( *s1 == *s2 && *s1 && *s2 ) s1++,s2++;

    return !(*s2-*s1);

}

#endif

// ----------------------------------------------------------------------------

// new operator to allow us to invoke constructors on previously allocated

// memory.

inline void *operator new(size_t size,  void *ptr) { return ptr; };

// =========================================================================

// Static objects

// Default memory allocator

static Cyg_LoaderMemAlloc memalloc;

// Loader object

static Cyg_Loader loader(&memalloc);

Cyg_Loader *Cyg_Loader::loader = &::loader;

// =========================================================================

// Main loader class members

// -------------------------------------------------------------------------

// Constructor

Cyg_Loader::Cyg_Loader( Cyg_LoaderMemAlloc *memalloc )

{

    CYG_REPORT_FUNCTION();

    error = 0;

    mem_default = memalloc;

    // build an object for the main program

    Cyg_LoaderMemBlock *obj = mem_default->alloc( sizeof(Cyg_LoadObject));

    main = new(obj->address) Cyg_LoadObject( );

    // Add to load list

    loadlist.add_head(main);

    error = main->get_error();

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// Destructor

Cyg_Loader::~Cyg_Loader()

{

    CYG_REPORT_FUNCTION();

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// Load an object and all its dependencies.

cyg_code Cyg_Loader::load( Cyg_LoaderStream& stream,

                           cyg_uint32 mode,

                           Cyg_LoadObject **object)

{

    CYG_REPORT_FUNCTION();

    CYG_REPORT_FUNCARG3XV( &stream, mode, object );

    cyg_code error = 0;

    Cyg_LoaderMemBlock *obj = mem_default->alloc( sizeof(Cyg_LoadObject));

    Cyg_LoadObject *pobj = NULL;

    pobj = new(obj->address) Cyg_LoadObject( stream, mode, mem_default, obj );

    error = pobj->get_error();

    if( error != 0 )

        goto finish;

    // Add this object to list before we do any relocations to make

    // the symbol lookups work.

    loadlist.add_tail(pobj);

    // The object is now loaded. We must now do any relocations.

    pobj->relocate();

    error = pobj->get_error();

    if( error != 0 )

        goto finish;

    // Handle PLT relocations if we are told to do so

// We always do this for now..    

//    if( mode & RTLD_NOW )

        pobj->relocate_plt();

    error = pobj->get_error();

 finish:

    if( error != 0 )

    {

        // remove object from list.

        loadlist.remove( pobj );

        pobj->~Cyg_LoadObject();

        mem_default->free( obj );

    }

    else

    {

        // return it from this function.

        *object = pobj;

    }

    CYG_REPORT_RETVAL(error);

    return error;

}

// -------------------------------------------------------------------------

// Close object and remove it from memory

cyg_code Cyg_Loader::close( Cyg_LoadObject *object )

{

    CYG_REPORT_FUNCTION();

    cyg_code error = 0;

    Cyg_LoaderMemBlock *block = object->get_block();

    object->~Cyg_LoadObject();

    if( block )

        block->free();

    CYG_REPORT_RETVAL(error);

    return error;

}

// -------------------------------------------------------------------------

// Translate current error code into a string.

const char *Cyg_Loader::error_string( )

{

    CYG_REPORT_FUNCTION();

    char *ret = "";

    CYG_REPORT_RETVAL(ret);

    return ret;

}

// -------------------------------------------------------------------------

// Look up a named symbol in loadlist

CYG_ADDRESS Cyg_Loader::hash_lookup_addr( const char *name )

{

    CYG_ADDRESS addr = 0;

    Cyg_LoadObject *object = loadlist.get_head();

    do

    {

        addr = object->hash_lookup_addr( name );

        if( addr != CYG_LOADER_NULLSYMADDR )

            break;

        object = object->get_next();

    } while( object != loadlist.get_head() );

    if( addr == CYG_LOADER_NULLSYMADDR )

        error = CYG_LOADERR_NO_SYMBOL;

    return addr;

}

// =========================================================================

// Loader Object class members

Cyg_LoadObject_Base::Cyg_LoadObject_Base()

{

    e_type = ET_EXEC;

    e_entry = 0;

    base = 0;

    dynamic = _DYNAMIC;

    parse_dynamic( dynamic );

}

// -------------------------------------------------------------------------

// Constructor - reads and allocates the executable.

Cyg_LoadObject_Base::Cyg_LoadObject_Base( Cyg_LoaderStream& stream,

                                cyg_uint32 amode,

                                Cyg_LoaderMemAlloc *mem )

{

    CYG_REPORT_FUNCTION();

    CYG_REPORT_FUNCARG3XV( &stream, mode, mem );

    Cyg_LoaderMemBlock *phblock = NULL;

    Cyg_LoaderMemBlock *block = NULL;

    Elf32_Phdr *phdr;

    Elf32_Phdr *dynhdr = NULL;

    cyg_uint32 memsize = 0;

    cyg_uint32 maxalign = 0;

    CYG_BYTE *memaddr;

    Elf32_Addr vaddr_low = 0x7FFFFFFF;

    Elf32_Addr vaddr_hi = 0;

    mode = amode;

    memalloc = mem;

    error = CYG_LOADERR_NOERROR;

    // OK, let's start by getting the ELF header...

    Elf32_Ehdr elf_hdr;

    error = stream.get_data( (CYG_BYTE *)&elf_hdr, sizeof( elf_hdr ) );

    if( error != 0 )

        goto finish;

    // Check that this is a valid ELF file and that the various header

    // fields match what we expect for our current architecture and

    // platform.

    if( !IS_ELF( elf_hdr ) )

        error = CYG_LOADERR_NOT_ELF;

    else if( elf_hdr.e_ident[EI_CLASS] != ELFCLASS32 )

        error = CYG_LOADERR_INVALID_CLASS;

#if CYG_BYTEORDER == CYG_LSBFIRST 

    else if( elf_hdr.e_ident[EI_DATA] != ELFDATA2LSB )

#else

    else if( elf_hdr.e_ident[EI_DATA] != ELFDATA2MSB )

#endif        

        error = CYG_LOADERR_INVALID_BYTEORDER;

    else if( elf_hdr.e_ident[EI_VERSION] != EV_CURRENT )

        error = CYG_LOADERR_INVALID_VERSION;

    else if( elf_hdr.e_machine != CYG_ELF_MACHINE )

        error = CYG_LOADERR_INVALID_MACHINE;

    else if( elf_hdr.e_version != EV_CURRENT )

        error = CYG_LOADERR_INVALID_VERSION;

    else if( elf_hdr.e_phentsize != sizeof(Elf32_Phdr) )

        error = CYG_LOADERR_INVALID_VERSION;

    if( error != 0 )

        goto finish;

    // OK that all seems in order, save some fields away for later.

    e_type = elf_hdr.e_type;

    e_entry = elf_hdr.e_entry;

    // Now we must read the program header and prepare to read the

    // object file into memory.

    error = stream.seek( elf_hdr.e_phoff );

    if( error != 0 )

        goto finish;

    // Allocate space for the header

    phblock = memalloc->alloc( elf_hdr.e_phentsize * elf_hdr.e_phnum );

    if( phblock == NULL )

    {

        error = CYG_LOADERR_NO_MEMORY;

        goto finish;

    }

    error = stream.get_data( (CYG_BYTE *)phblock->address, sizeof(Elf32_Phdr)*elf_hdr.e_phnum );

    if( error != 0 )

        goto finish;

    phdr = (Elf32_Phdr *)phblock->address;

    // Loop over the program headers, totalling the sizes of the the

    // PT_LOAD entries and saving a pointer to the PT_DYNAMIC entry

    // when we find it.

    // Since the segments must retain the same relationship to

    // eachother in memory that their virtual addresses do in the

    // headers, we determine the amount of memory needed by finding

    // the extent of the virtual addresses covered by the executable.

    for( int i = 0; i < elf_hdr.e_phnum; i++,phdr++ )

    {

        if( phdr->p_type == PT_DYNAMIC )

        {

            dynhdr = phdr;

            continue;

        }

        if( phdr->p_type != PT_LOAD )

            continue;

        if( phdr->p_vaddr < vaddr_low )

            vaddr_low = phdr->p_vaddr;

        if( (phdr->p_vaddr+phdr->p_memsz) > vaddr_hi )

            vaddr_hi = phdr->p_vaddr+phdr->p_memsz;

        if( phdr->p_align > maxalign )

            maxalign = phdr->p_align;

    }

    // Calculate how much memory we need and allocate it

    memsize = vaddr_hi - vaddr_low;

    block = memalloc->alloc( memsize, maxalign );

    if( block == NULL )

    {

        error = CYG_LOADERR_NO_MEMORY;

        goto finish;

    }

    // Attach to segments list

    segs.add_tail( block );

    // Calculate the base address for this executable. This is the

    // difference between the actual address the executable is loaded

    // at and its lowest virtual address. This value must be added to

    // all addresses derived from the executable to relocate them into

    // the real memory space.

    base = (CYG_ADDRESS)block->address - vaddr_low;

    // Loop over the program headers again, this time loading them

    // into the memory segment we have allocated and clearing any

    // unused areas to zero.

    phdr = (Elf32_Phdr *)phblock->address;

    memaddr = (CYG_BYTE *)block->address;

    for( int i = 0; i < elf_hdr.e_phnum; i++,phdr++ )

    {

        if( phdr->p_type != PT_LOAD )

            continue;

        error = stream.seek( phdr->p_offset );

        if( error != 0 ) break;

        // Calculate the actual load address for this segment.

        CYG_BYTE *loadaddr = (CYG_BYTE *)(phdr->p_vaddr + base);

        error = stream.get_data( loadaddr, phdr->p_filesz );

        if( error != 0 ) break;

        // If the memory size is more than we got from the file, zero the remainder.

        if( phdr->p_filesz < phdr->p_memsz )

            memset( loadaddr+phdr->p_filesz,

                    0,

                    phdr->p_memsz-phdr->p_filesz );

    }

    dynamic = (Elf32_Dyn *)(dynhdr->p_vaddr + base);

    parse_dynamic( dynamic );

 finish:

    if( phblock != NULL )

        memalloc->free( phblock );

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// Parse the dynamic segment 

void Cyg_LoadObject_Base::parse_dynamic( Elf32_Dyn *dynamic )

{

    CYG_REPORT_FUNCTION();

    flags = 0;

    for(;; dynamic++)

    {

        switch( dynamic->d_tag )

        {

        case DT_NULL:                   /* marks end of _DYNAMIC array */

            return;

        case DT_NEEDED:                 /* string table offset of needed lib */

            break;                      // ignore for now

        case DT_PLTRELSZ:               /* size of relocation entries in PLT */

            pltrelsz = dynamic->d_un.d_val;

            break;

        case DT_PLTGOT:                 /* address PLT/GOT */

            pltgot = dynamic->d_un.d_ptr + base;

            break;

        case DT_HASH:                   /* address of symbol hash table */

            hash = (Elf_Hash *)(dynamic->d_un.d_ptr + base);

            bucket = (Elf32_Word *)(hash+1);

            chain = bucket+hash->nbucket;

            break;

        case DT_STRTAB:                 /* address of string table */

            strtab = (unsigned char *)(dynamic->d_un.d_ptr + base);

            break;

        case DT_SYMTAB:                 /* address of symbol table */

            symtab = (Elf32_Sym *)(dynamic->d_un.d_ptr + base);

            break;

        case DT_RELA:                   /* address of relocation table */

            rela = (Elf32_Rela *)(dynamic->d_un.d_ptr + base);

            break;

        case DT_RELASZ:                 /* size of relocation table */

            relasize = dynamic->d_un.d_val;

            break;

        case DT_RELAENT:                /* size of relocation entry */

            relaent = dynamic->d_un.d_val;

            break;

        case DT_STRSZ:                  /* size of string table */

            strsize = dynamic->d_un.d_val;

            break;

        case DT_SYMENT:                 /* size of symbol table entry */

            syment = dynamic->d_un.d_val;

            break;

        case DT_INIT:                   /* address of initialization func. */

            init = dynamic->d_un.d_ptr + base;

            break;

        case DT_FINI:                   /* address of termination function */

            fini = dynamic->d_un.d_ptr + base;

            break;

        case DT_SONAME:                 /* string table offset of shared obj */

            soname = dynamic->d_un.d_val;

            break;

        case DT_SYMBOLIC:               /* start sym search in shared obj. */

            flags |= DF_SYMBOLIC;

            break;

        case DT_REL:                    /* address of rel. tbl. w addends */

            rel = (Elf32_Rel *)(dynamic->d_un.d_ptr + base);

            break;

        case DT_RELSZ:                  /* size of DT_REL relocation table */

            relsize = dynamic->d_un.d_val;

            break;

        case DT_RELENT:                 /* size of DT_REL relocation entry */

            relent = dynamic->d_un.d_val;

            break;

        case DT_PLTREL:                 /* PLT referenced relocation entry */

            pltrel = dynamic->d_un.d_val;

            break;

        case DT_DEBUG:                  /* Debug data */

            break;                      /* ignore for now */

        case DT_TEXTREL:                /* Allow rel. mod. to unwritable seg */

            flags |= DF_TEXTREL;

            break;

        case DT_JMPREL:                 /* add. of PLT's relocation entries */

            jmprel = dynamic->d_un.d_ptr + base;

            break;

        case DT_BIND_NOW:               /* Bind now regardless of env setting */

            flags |= DF_BIND_NOW;

            break;

        case DT_INIT_ARRAY:             /* init array address */

            init_array = (Elf32_Addr *)(dynamic->d_un.d_ptr + base);

            break;

        case DT_FINI_ARRAY:             /* fini array address */

            fini_array = (Elf32_Addr *)(dynamic->d_un.d_ptr + base);

            break;

        case DT_INIT_ARRAYSZ:           /* init array size */

            init_array_sz = dynamic->d_un.d_val;

            break;

        case DT_FINI_ARRAYSZ:           /* fini array size */

            fini_array_sz = dynamic->d_un.d_val;

            break;

        case DT_FLAGS:                  /* flags */

            flags |= dynamic->d_un.d_val;

            break;

        case DT_PREINIT_ARRAY:          /* preinit array address */

            pre_init_array = (Elf32_Addr *)(dynamic->d_un.d_ptr + base);

            break;

        case DT_PREINIT_ARRAYSZ:        /* preinit array size */

            pre_init_array_sz = dynamic->d_un.d_val;

            break;

        default:

            // handle format-specific entries

            break;

        }

    }

    CYG_REPORT_RETURN();

}

// -------------------------------------------------------------------------

// Get the symbol name from the current object's symbol table, look it

// up in the hash tables of the loaded objects, and return its address.

CYG_ADDRESS Cyg_LoadObject_Base::get_sym_addr_from_ix( Elf32_Word ix )

{

    Elf32_Sym *sym = get_sym( ix );

    if( sym == NULL ) return 0;

    const char *name = get_name( sym->st_name );

    // If the symbol has local binding, we must look for

    // it in this object only.

    if( ELF32_ST_BIND(sym->st_info) == STB_LOCAL )

         return hash_lookup_addr( name );

    // Otherwise search the loaded objects in load order

    return Cyg_Loader::loader->hash_lookup_addr( name );

}

// -------------------------------------------------------------------------

// Lookup the name in our hash table and return the symbol table entry

Elf32_Sym *Cyg_LoadObject_Base::hash_lookup( const char *name )

{

    Elf32_Sym *ret = NULL;

    if( hash == NULL )

    {

        error = CYG_LOADERR_NO_HASHTABLE;

        return NULL;

    }

    error = CYG_LOADERR_NO_SYMBOL;

    Elf32_Word ix = elf_hash( (const unsigned char *)name );

    ix %= hash->nbucket;

    // get head of chain

    Elf32_Word iy = bucket[ ix ];

    while( iy != STN_UNDEF )

    {

        Elf32_Sym *sym = get_sym( iy );

        const char *sname = get_name( sym->st_name );

        if( streq( name, sname ) )

        {

            ret = sym;

            error = CYG_LOADERR_NOERROR;

            break;

        }

        iy = chain[ iy ];

    }

    return ret;

}

// -------------------------------------------------------------------------

// Lookup the given name in our symbol table and return it's value

// relocated to our load address.

CYG_ADDRESS Cyg_LoadObject_Base::hash_lookup_addr( const char *name )

{

    Elf32_Sym *sym = hash_lookup( name );

    if( sym == NULL )

        return CYG_LOADER_NULLSYMADDR;

    // Check that this symbol is for a defined object, if its type is

    // NOTYPE then it is undefined, here, and we cannot take its address.

    // Hopefully it is defined in some other object.

    if( ELF32_ST_TYPE(sym->st_info) == STT_NOTYPE )

    {

        error = CYG_LOADERR_NO_SYMBOL;

        return CYG_LOADER_NULLSYMADDR;

    }

    return sym->st_value + base;

}

// -------------------------------------------------------------------------

// ELF hash function

// This is the standard hash function used for indexing the bucket

// array in the hash table.

unsigned long Cyg_LoadObject_Base::elf_hash( const unsigned char *name )

{

    unsigned long h = 0, g;

    while( *name )

    {

        h = ( h << 4 ) + *name++;

        if( (g = h & 0xf0000000) != 0 )

            h ^= g >> 24;

        h &= ~g;

    }

    return h;

}

// -------------------------------------------------------------------------

//

Elf32_Sym *Cyg_LoadObject_Base::get_sym( Elf32_Word ix )

{

    if( symtab == NULL )

        return NULL;

    return &symtab[ix];

}

char *Cyg_LoadObject_Base::get_name( Elf32_Word offset )

{

    if( strtab == NULL || offset > strsize )

        return NULL;