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{
Copyright (c) 1998-2006 by Peter Vreman
Contains the binary elf writer
This program 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 of the License, or
(at your option) any later version.
This program 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 this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
****************************************************************************
}
unit ogelf;
{$i fpcdefs.inc}
interface
uses
{ common }
cclasses,globtype,
{ target }
systems,
{ assembler }
aasmbase,assemble,
{ ELF definitions }
elfbase,
{ output }
ogbase,
owbase;
type
{$ifdef cpu64bitaddr}
TElfsechdr = TElf64sechdr;
{$else cpu64bitaddr}
TElfsechdr = TElf32sechdr;
{$endif cpu64bitaddr}
TElfObjSection = class(TObjSection)
public
shstridx,
shtype,
shflags,
shlink,
shinfo,
shentsize : longint;
constructor create(AList:TFPHashObjectList;const Aname:string;Aalign:longint;Aoptions:TObjSectionOptions);override;
constructor create_ext(aobjdata:TObjData;const Aname:string;Ashtype,Ashflags:longint;Aalign:longint;Aentsize:longint);
constructor create_reloc(aobjdata:TObjData;const Aname:string;allocflag:boolean);
procedure writeReloc_internal(aTarget:TObjSection;offset:aword;len:byte;reltype:TObjRelocationType);override;
end;
TElfSymtabKind = (esk_obj,esk_exe,esk_dyn);
TElfSymtab = class(TElfObjSection)
public
kind: TElfSymtabKind;
fstrsec: TObjSection;
symidx: longint;
tlsbase: aword;
constructor create(aObjData:TObjData;aKind:TElfSymtabKind);reintroduce;
procedure writeSymbol(objsym:TObjSymbol;nameidx:longword=0);
procedure writeInternalSymbol(avalue:aword;astridx:longword;ainfo:byte;ashndx:word);
end;
TElfObjData = class(TObjData)
public
ident: TElfIdent;
flags: longword;
{$ifdef mips}
gp_value: longword;
{$endif mips}
constructor create(const n:string);override;
function sectionname(atype:TAsmSectiontype;const aname:string;aorder:TAsmSectionOrder):string;override;
procedure CreateDebugSections;override;
procedure writereloc(data:aint;len:aword;p:TObjSymbol;reltype:TObjRelocationType);override;
end;
TElfObjectOutput = class(tObjOutput)
private
symtabsect: TElfSymtab;
shstrtabsect: TElfObjSection;
procedure createrelocsection(s:TElfObjSection;data:TObjData);
procedure createshstrtab(data:TObjData);
procedure createsymtab(data: TObjData);
procedure writesectionheader(s:TElfObjSection);
procedure section_write_symbol(p:TObject;arg:pointer);
procedure section_count_sections(p:TObject;arg:pointer);
procedure section_create_relocsec(p:TObject;arg:pointer);
procedure section_write_sechdr(p:TObject;arg:pointer);
protected
function writedata(data:TObjData):boolean;override;
public
constructor Create(AWriter:TObjectWriter);override;
end;
TElfAssembler = class(tinternalassembler)
constructor create(info: pasminfo; smart:boolean);override;
end;
PSectionRec=^TSectionRec;
TSectionRec=record
sec: TObjSection;
relocpos: aword;
relocs: longint;
relentsize: longint;
end;
TElfsecheaderarray=array of TElfsechdr;
TObjSymbolClass=class of TObjSymbol;
TElfObjInput=class(TObjInput)
private
FSecTbl: PSectionRec;
FSymTbl: PPointer;
FLoaded: PBoolean;
shdrs: TElfsecheaderarray;
nsects: longword;
shoffset: aword;
shstrndx: longword;
symtabndx: longword;
shstrtab: PChar;
strtab: PChar;
shstrtablen: longword;
strtablen: longword;
symtaboffset: aword;
syms: longword;
localsyms: longword;
symversions: PWord;
dynobj: boolean;
CObjSymbol: TObjSymbolClass;
verdefs: TFPHashObjectList;
function LoadHeader(out objdata:TObjData):boolean;
procedure LoadSection(const shdr:TElfsechdr;index:longint;objdata:TObjData);
procedure LoadRelocations(const secrec:TSectionRec);
procedure LoadSymbols(objdata:TObjData;count,locals:longword);
procedure LoadDynamic(const shdr:TElfsechdr;objdata:TObjData);
public
constructor Create;override;
destructor Destroy;override;
function ReadObjData(AReader:TObjectreader;out objdata:TObjData):boolean;override;
class function CanReadObjData(AReader:TObjectreader):boolean;override;
function CreateSection(const shdr:TElfsechdr;index:longint;objdata:TObjData;
out secname:string):TElfObjSection;
function ReadBytes(offs:longint;out buf;len:longint):boolean;
end;
TElfVersionDef = class(TFPHashObject)
public
index: longword;
end;
TElfDynamicObjData = class(TElfObjData)
private
FVersionDefs: TFPHashObjectList;
public
soname_strofs: longword;
vernaux_count: longword;
constructor create(const n:string);override;
destructor destroy;override;
property versiondefs:TFPHashObjectList read FVersionDefs;
end;
TVersionedObjSymbol = class(TObjSymbol)
private
FVersion: TElfVersionDef;
public
property version: TElfVersionDef read FVersion write FVersion;
end;
TRelocNameProc=function(reltyp:byte):string;
TEncodeRelocProc=function(objrel:TObjRelocation):byte;
TLoadRelocProc=procedure(objrel:TObjRelocation);
TLoadSectionProc=function(objinput:TElfObjInput;objdata:TObjData;const shdr:TElfsechdr;shindex:longint):boolean;
TEncodeFlagsProc=function:longword;
TDynamicReloc=(
dr_relative,
dr_glob_dat,
dr_jump_slot,
dr_copy,
dr_irelative
);
TElfTarget=record
max_page_size: longword;
exe_image_base: longword;
machine_code: word;
relocs_use_addend: boolean;
dyn_reloc_codes: array[TDynamicReloc] of byte;
relocname: TRelocNameProc;
encodereloc: TEncodeRelocProc;
loadreloc: TLoadRelocProc;
loadsection: TLoadSectionProc;
encodeflags: TEncodeFlagsProc;
end;
TElfExeSection=class(TExeSection)
public
secshidx : longword; { index of the section header }
shstridx,
shtype,
shflags,
shlink,
shinfo,
shentsize : longword;
procedure AddObjSection(objsec:TObjSection;ignoreprops:boolean=false);override;
end;
TElfSegment=class
public
ptype: longword;
pflags: longword;
DataPos: aword;
DataSize: aword;
MemPos: aword;
MemSize: aword;
align: longword;
//physaddr: aword;
FSectionList: TFPObjectList;
constructor Create(atype,aflags,aalign:longword);
destructor Destroy; override;
procedure Add(exesec:TExeSection);
end;
TElfExeOutput=class(TExeOutput)
private
segmentlist: TFPObjectList;
textseg,
dataseg,
noteseg,
phdrseg: TElfSegment;
shstrtabsect: TElfObjSection;
symtab: TElfSymtab;
shoffset: aword;
gotwritten: boolean;
{ dynamic linking }
dynsymnames: Plongword;
dynsymtable: TElfSymtab;
interpobjsec: TObjSection;
FInterpreter: pshortstring;
verneedcount,
verdefcount: longword;
symversec,
verdefsec,
verneedsec,
hashobjsec: TElfObjSection;
neededlist: TFPHashList;
dyncopysyms: TFPObjectList;
preinitarraysec,
initarraysec,
finiarraysec: TObjSection;
function AttachSection(objsec:TObjSection):TElfExeSection;
function CreateSegment(atype,aflags,aalign:longword):TElfSegment;
procedure WriteHeader;
procedure WriteDynamicSymbolsHash;
procedure WriteVersionSections;
procedure WriteDynamicTags;
procedure FinishDynamicTags;
procedure exesection_write_header(p:TObject;arg:Pointer);
procedure segment_write_header(p:TObject;arg:Pointer);
procedure mempos_segment(seg:TElfSegment);
procedure datapos_segment(seg:TElfSegment);
procedure MapSectionsToSegments;
procedure WriteStaticSymtable;
procedure WriteShstrtab;
procedure FixupSectionLinks;
procedure InitDynlink;
procedure OrderOrphanSections;
protected
dynamiclink: boolean;
hastextrelocs: boolean;
gotsymbol: TObjSymbol;
dynsymlist: TFPObjectList;
dynamicsec,
gotobjsec: TObjSection;
dynbssobjsec,
pltobjsec,
gotpltobjsec,
pltrelocsec,
ipltrelocsec,
dynrelocsec: TElfObjSection;
dynreloclist: TFPObjectList;
tlsseg: TElfSegment;
relative_reloc_count: longint;
gotsize: aword;
dynrelsize: aword;
procedure PrepareGOT;virtual;
function AllocGOTSlot(objsym: TObjSymbol):boolean;virtual;
procedure CreateGOTSection;virtual;
procedure make_dynamic_if_undefweak(exesym:TExeSymbol);
procedure WriteDynRelocEntry(dataofs:aword;typ:byte;symidx:aword;addend:aword);
procedure CreatePLT;virtual;
procedure WriteFirstPLTEntry;virtual;abstract;
procedure WritePLTEntry(exesym:TExeSymbol);virtual;
procedure WriteIndirectPLTEntry(exesym:TExeSymbol);virtual;
procedure WriteTargetDynamicTags;virtual;
procedure GOTRelocPass1(objsec:TObjSection;var idx:longint);virtual;abstract;
procedure ReportNonDSOReloc(reltyp:byte;objsec:TObjSection;ObjReloc:TObjRelocation);
procedure ReportRelocOverflow(reltyp:byte;objsec:TObjSection;ObjReloc:TObjRelocation);
procedure WriteDynTag(aTag:longword;aValue:longword);
procedure WriteDynTag(aTag:longword;aSection:TObjSection;aOffs:aword=0);
procedure Do_Mempos;virtual;
public
constructor Create;override;
destructor Destroy;override;
procedure Load_Start;override;
procedure Load_DynamicObject(ObjData:TObjData;asneeded:boolean);override;
procedure Order_Start;override;
procedure Order_end;override;
procedure AfterUnusedSectionRemoval;override;
procedure MemPos_Start;override;
procedure MemPos_ExeSection(const aname:string);override;
procedure DataPos_Start;override;
procedure DataPos_ExeSection(const aname:string);override;
function writeData:boolean;override;
procedure GenerateLibraryImports(ImportLibraryList:TFPHashObjectList);override;
property interpreter:pshortstring read FInterpreter write FInterpreter;
end;
var
ElfExeOutputClass: TExeOutputClass;
ElfTarget: TElfTarget;
const
{ Bits of TObjSymbol.refs field }
symref_plt = 1;
symref_from_text = 2;
implementation
uses
SysUtils,
verbose,
export,expunix,
cutils,globals,fmodule,owar;
const
symbolresize = 200*18;
{$ifdef cpu64bitaddr}
const
ELFCLASS = ELFCLASS64;
type
telfheader = telf64header;
telfreloc = telf64reloc;
telfsymbol = telf64symbol;
telfproghdr = telf64proghdr;
telfdyn = telf64dyn;
function ELF_R_INFO(sym:longword;typ:byte):qword;inline;
begin
result:=(qword(sym) shl 32) or typ;
end;
{$else cpu64bitaddr}
const
ELFCLASS = ELFCLASS32;
type
telfheader = telf32header;
telfreloc = telf32reloc;
telfsymbol = telf32symbol;
telfproghdr = telf32proghdr;
telfdyn = telf32dyn;
function ELF_R_INFO(sym:longword;typ:byte):longword;inline;
begin
result:=(sym shl 8) or typ;
end;
{$endif cpu64bitaddr}
{****************************************************************************
Helpers
****************************************************************************}
procedure encodesechdrflags(aoptions:TObjSectionOptions;out AshType:longint;out Ashflags:longint);
begin
{ Section Type }
AshType:=SHT_PROGBITS;
if oso_strings in aoptions then
AshType:=SHT_STRTAB
else if not(oso_data in aoptions) then
AshType:=SHT_NOBITS;
{ Section Flags }
Ashflags:=0;
if oso_load in aoptions then
Ashflags:=Ashflags or SHF_ALLOC;
if oso_executable in aoptions then
Ashflags:=Ashflags or SHF_EXECINSTR;
if oso_write in aoptions then
Ashflags:=Ashflags or SHF_WRITE;
end;
procedure decodesechdrflags(AshType:longint;Ashflags:longint;out aoptions:TObjSectionOptions);
begin
aoptions:=[];
{ Section Type }
if AshType<>SHT_NOBITS then
include(aoptions,oso_data);
if AshType=SHT_STRTAB then
include(aoptions,oso_strings);
{ Section Flags }
if Ashflags and SHF_ALLOC<>0 then
include(aoptions,oso_load);
if Ashflags and SHF_WRITE<>0 then
include(aoptions,oso_write);
if Ashflags and SHF_EXECINSTR<>0 then
include(aoptions,oso_executable);
end;
{****************************************************************************
TElfObjSection
****************************************************************************}
constructor TElfObjSection.create(AList:TFPHashObjectList;const Aname:string;Aalign:longint;Aoptions:TObjSectionOptions);
begin
inherited create(AList,Aname,Aalign,aoptions);
index:=0;
shstridx:=0;
encodesechdrflags(aoptions,shtype,shflags);
shlink:=0;
shinfo:=0;
if name='.stab' then
shentsize:=sizeof(TObjStabEntry);
end;
constructor TElfObjSection.create_ext(aobjdata:TObjData;const Aname:string;Ashtype,Ashflags:longint;Aalign:longint;Aentsize:longint);
var
aoptions : TObjSectionOptions;
begin
decodesechdrflags(Ashtype,Ashflags,aoptions);
inherited create(aobjdata.ObjSectionList,Aname,Aalign,aoptions);
objdata:=aobjdata;
index:=0;
shstridx:=0;
shtype:=AshType;
shflags:=AshFlags;
shentsize:=Aentsize;
end;
const
relsec_prefix:array[boolean] of string[5] = ('.rel','.rela');
relsec_shtype:array[boolean] of longword = (SHT_REL,SHT_RELA);
constructor TElfObjSection.create_reloc(aobjdata:TObjData;const Aname:string;allocflag:boolean);
begin
create_ext(aobjdata,
relsec_prefix[ElfTarget.relocs_use_addend]+aname,
relsec_shtype[ElfTarget.relocs_use_addend],
SHF_ALLOC*ord(allocflag),
sizeof(pint),
(2+ord(ElfTarget.relocs_use_addend))*sizeof(pint));
end;
procedure TElfObjSection.writeReloc_internal(aTarget:TObjSection;offset:aword;len:byte;reltype:TObjRelocationType);
var
reloc: TObjRelocation;
begin
reloc:=TObjRelocation.CreateSection(Size,aTarget,reltype);
reloc.size:=len;
ObjRelocations.Add(reloc);
if reltype=RELOC_RELATIVE then
{ ARM does not require this adjustment, other CPUs must be checked }
{$if defined(i386) or defined(x86_64)}
dec(offset,len)
{$endif i386 or x86_64}
else if reltype<>RELOC_ABSOLUTE then
InternalError(2012062401);
if ElfTarget.relocs_use_addend then
begin
reloc.orgsize:=offset;
offset:=0;
end;
write(offset,len);
end;
{****************************************************************************
TElfObjData
****************************************************************************}
constructor TElfObjData.create(const n:string);
begin
inherited create(n);
CObjSection:=TElfObjSection;
end;
function TElfObjData.sectionname(atype:TAsmSectiontype;const aname:string;aorder:TAsmSectionOrder):string;
const
secnames : array[TAsmSectiontype] of string[length('__DATA, __datacoal_nt,coalesced')] = ('','',
{ TODO: sec_rodata is still writable }
'.text','.data','.data','.rodata','.bss','.threadvar',
'.pdata',
'.text', { darwin stubs }
'__DATA,__nl_symbol_ptr',
'__DATA,__la_symbol_ptr',
'__DATA,__mod_init_func',
'__DATA,__mod_term_func',
'.stab','.stabstr',
'.idata$2','.idata$4','.idata$5','.idata$6','.idata$7','.edata',
'.eh_frame',
'.debug_frame','.debug_info','.debug_line','.debug_abbrev','.debug_aranges','.debug_ranges',
'.fpc',
'.toc',
'.init',
'.fini',
'.objc_class',
'.objc_meta_class',
'.objc_cat_cls_meth',
'.objc_cat_inst_meth',
'.objc_protocol',
'.objc_string_object',
'.objc_cls_meth',
'.objc_inst_meth',
'.objc_cls_refs',
'.objc_message_refs',
'.objc_symbols',
'.objc_category',
'.objc_class_vars',
'.objc_instance_vars',
'.objc_module_info',
'.objc_class_names',
'.objc_meth_var_types',
'.objc_meth_var_names',
'.objc_selector_strs',
'.objc_protocol_ext',
'.objc_class_ext',
'.objc_property',
'.objc_image_info',
'.objc_cstring_object',
'.objc_sel_fixup',
'__DATA,__objc_data',
'__DATA,__objc_const',
'.objc_superrefs',
'__DATA, __datacoal_nt,coalesced',
'.objc_classlist',
'.objc_nlclasslist',
'.objc_catlist',
'.obcj_nlcatlist',
'.objc_protolist',
'.stack',
'.heap'
);
var
sep : string[3];
secname : string;
begin
{ section type user gives the user full controll on the section name }
if atype=sec_user then
result:=aname
else
begin
secname:=secnames[atype];
if (atype=sec_fpc) and (Copy(aname,1,3)='res') then
begin
result:=secname+'.'+aname;
exit;
end;
if create_smartlink_sections and (aname<>'') then
begin
case aorder of
secorder_begin :
sep:='.b_';
secorder_end :
sep:='.z_';
else
sep:='.n_';
end;
result:=secname+sep+aname
end
else
result:=secname;
end;
end;
procedure TElfObjData.CreateDebugSections;
begin
if target_dbg.id=dbg_stabs then
begin
stabssec:=createsection(sec_stab);
stabstrsec:=createsection(sec_stabstr);
end;
end;
procedure TElfObjData.writereloc(data:aint;len:aword;p:TObjSymbol;reltype:TObjRelocationType);
var
symaddr : aint;
objreloc: TObjRelocation;
begin
if CurrObjSec=nil then
internalerror(200403292);
objreloc:=nil;
if assigned(p) then
begin
{ real address of the symbol }
symaddr:=p.address;
{ Local ObjSymbols can be resolved already or need a section reloc }
if (p.bind=AB_LOCAL) and
(reltype in [RELOC_RELATIVE,RELOC_ABSOLUTE{$ifdef x86_64},RELOC_ABSOLUTE32{$endif x86_64}{$ifdef arm},RELOC_RELATIVE_24,RELOC_RELATIVE_CALL{$endif arm}]) then
begin
{$ifdef ARM}
if (reltype in [RELOC_RELATIVE_24,RELOC_RELATIVE_CALL]) and
(p.objsection=CurrObjSec) then
begin
data:=aint((data and $ff000000) or (((((data and $ffffff) shl 2)+(symaddr-CurrObjSec.Size)) shr 2) and $FFFFFF)); // TODO: Check overflow
end
else
{$endif ARM}
{ For a reltype relocation in the same section the
value can be calculated }
if (p.objsection=CurrObjSec) and
(reltype=RELOC_RELATIVE) then
inc(data,symaddr-len-CurrObjSec.Size)
else
begin
objreloc:=TObjRelocation.CreateSection(CurrObjSec.Size,p.objsection,reltype);
CurrObjSec.ObjRelocations.Add(objreloc);
inc(data,symaddr);
end;
end
else
begin
objreloc:=TObjRelocation.CreateSymbol(CurrObjSec.Size,p,reltype);
CurrObjSec.ObjRelocations.Add(objreloc);
{ If target is a local label and it isn't handled above,
patch its type in order to get it written to symtable.
This may happen e.g. when taking address of Pascal label in PIC mode. }
if (p.bind=AB_LOCAL) and (p.typ=AT_LABEL) then
p.typ:=AT_ADDR;
end;
end;
if assigned(objreloc) then
begin
objreloc.size:=len;
if reltype in [RELOC_RELATIVE{$ifdef x86},RELOC_PLT32{$endif}{$ifdef x86_64},RELOC_GOTPCREL{$endif}] then
dec(data,len);
if ElfTarget.relocs_use_addend then
begin
objreloc.orgsize:=aword(data);
data:=0;
end;
end;
CurrObjSec.write(data,len);
end;
{****************************************************************************
TElfDynamicObjData
****************************************************************************}
constructor TElfDynamicObjData.create(const n:string);
begin
inherited Create(n);
FVersionDefs:=TFPHashObjectList.create(true);
{ Default symversions with indices 0 and 1 }
TElfVersionDef.create(FVersionDefs,'*local*');
TElfVersionDef.create(FVersionDefs,'*global*');
end;
destructor TElfDynamicObjData.destroy;
begin
FVersionDefs.free;
inherited Destroy;
end;
{****************************************************************************
TElfSymtab
****************************************************************************}
const
symsecnames: array[boolean] of string[8] = ('.symtab','.dynsym');
strsecnames: array[boolean] of string[8] = ('.strtab','.dynstr');
symsectypes: array[boolean] of longword = (SHT_SYMTAB,SHT_DYNSYM);
symsecattrs: array[boolean] of longword = (0,SHF_ALLOC);
constructor TElfSymtab.create(aObjData:TObjData;aKind:TElfSymtabKind);
var
dyn:boolean;
begin
dyn:=(aKind=esk_dyn);
create_ext(aObjData,symsecnames[dyn],symsectypes[dyn],symsecattrs[dyn],sizeof(pint),sizeof(TElfSymbol));
fstrsec:=TElfObjSection.create_ext(aObjData,strsecnames[dyn],SHT_STRTAB,symsecattrs[dyn],1,0);
fstrsec.writezeros(1);
writezeros(sizeof(TElfSymbol));
symidx:=1;
shinfo:=1;
kind:=aKind;
end;
procedure TElfSymtab.writeInternalSymbol(avalue:aword;astridx:longword;ainfo:byte;ashndx:word);
var
elfsym:TElfSymbol;
begin
fillchar(elfsym,sizeof(elfsym),0);
elfsym.st_value:=avalue;
elfsym.st_name:=astridx;
elfsym.st_info:=ainfo;
elfsym.st_shndx:=ashndx;
inc(symidx);
inc(shinfo);
MaybeSwapElfSymbol(elfsym);
write(elfsym,sizeof(elfsym));
end;
procedure TElfSymtab.writeSymbol(objsym:TObjSymbol;nameidx:longword);
var
elfsym:TElfSymbol;
begin
fillchar(elfsym,sizeof(elfsym),0);
if nameidx=0 then
elfsym.st_name:=fstrsec.writestr(objsym.name)
else
elfsym.st_name:=nameidx;
elfsym.st_size:=objsym.size;
elfsym.st_value:=objsym.address;
{$ifdef ARM}
if objsym.ThumbFunc then
inc(elfsym.st_value);
{$endif ARM}
case objsym.bind of
AB_LOCAL :
begin
elfsym.st_info:=STB_LOCAL shl 4;
inc(shinfo);
end;
AB_COMMON :
begin
elfsym.st_value:=size_2_align(objsym.size);
elfsym.st_info:=STB_GLOBAL shl 4;
elfsym.st_shndx:=SHN_COMMON;
end;
AB_EXTERNAL :
elfsym.st_info:=STB_GLOBAL shl 4;
AB_WEAK_EXTERNAL :
elfsym.st_info:=STB_WEAK shl 4;
AB_GLOBAL :
elfsym.st_info:=STB_GLOBAL shl 4;
else
InternalError(2012111801);
end;
{ External symbols must be NOTYPE in relocatable files }
if (objsym.bind<>AB_EXTERNAL) or (kind<>esk_obj) then
begin
case objsym.typ of
AT_FUNCTION :
elfsym.st_info:=elfsym.st_info or STT_FUNC;
AT_DATA,
AT_METADATA:
elfsym.st_info:=elfsym.st_info or STT_OBJECT;
AT_TLS:
elfsym.st_info:=elfsym.st_info or STT_TLS;
AT_GNU_IFUNC:
elfsym.st_info:=elfsym.st_info or STT_GNU_IFUNC;
{ other types are implicitly mapped to STT_NOTYPE }
end;
end;
if objsym.bind<>AB_COMMON then
begin
if kind<>esk_obj then
begin
if assigned(objsym.objsection) and assigned(objsym.objsection.ExeSection) then
begin
if (objsym.typ=AT_TLS) then
elfsym.st_value:=elfsym.st_value-tlsbase
else if (oso_plt in objsym.objsection.SecOptions) then
elfsym.st_value:=0
else
elfsym.st_shndx:=TElfExeSection(objsym.objsection.ExeSection).secshidx;
end;
end
else
begin
if assigned(objsym.objsection) then
elfsym.st_shndx:=objsym.objsection.index
else
elfsym.st_shndx:=SHN_UNDEF;
objsym.symidx:=symidx;
end;
end;
inc(symidx);
MaybeSwapElfSymbol(elfsym);
write(elfsym,sizeof(TElfSymbol));
end;
{****************************************************************************
TElfObjectOutput
****************************************************************************}
constructor TElfObjectOutput.create(AWriter:TObjectWriter);
begin
inherited Create(AWriter);
CObjData:=TElfObjData;
end;
procedure TElfObjectOutput.createrelocsection(s:TElfObjSection;data:TObjData);
var
i : longint;
rel : telfreloc;
objreloc : TObjRelocation;
relsym : longint;
relocsect : TElfObjSection;
begin
{ create the reloc section }
relocsect:=TElfObjSection.create_reloc(data,s.name,false);
relocsect.shlink:=symtabsect.index;
relocsect.shinfo:=s.index;
{ add the relocations }
for i:=0 to s.Objrelocations.count-1 do
begin
objreloc:=TObjRelocation(s.Objrelocations[i]);
{ Symbol }
if assigned(objreloc.symbol) then
begin
if objreloc.symbol.symidx=-1 then
begin
writeln(objreloc.symbol.Name);
internalerror(200603012);
end;
relsym:=objreloc.symbol.symidx;
end
else
begin
if objreloc.objsection<>nil then
relsym:=objreloc.objsection.secsymidx
else
relsym:=SHN_UNDEF;
end;
rel.address:=objreloc.dataoffset;
rel.info:=ELF_R_INFO(relsym,ElfTarget.encodereloc(objreloc));
{$push}{$r-}
rel.addend:=objreloc.orgsize;
{$pop}
{ write reloc }
{ ElfXX_Rel is essentially ElfXX_Rela without the addend field. }
MaybeSwapElfReloc(rel);
relocsect.write(rel,relocsect.shentsize);
end;
end;
procedure TElfObjectOutput.section_write_symbol(p:TObject;arg:pointer);
begin
{ Must not write symbols for internal sections like .symtab }
{ TODO: maybe use inclusive list of section types instead }
if (TElfObjSection(p).shtype in [SHT_SYMTAB,SHT_STRTAB,SHT_REL,SHT_RELA]) then
exit;
TObjSection(p).secsymidx:=symtabsect.symidx;
symtabsect.writeInternalSymbol(0,0,STT_SECTION,TObjSection(p).index);
end;
procedure TElfObjectOutput.createsymtab(data: TObjData);
var
i : longint;
objsym : TObjSymbol;
begin
with data do
begin
{ section symbols }
ObjSectionList.ForEachCall(@section_write_symbol,nil);
{ First the Local Symbols, this is required by ELF. The localsyms
count stored in shinfo is used to skip the local symbols
when traversing the symtab }
for i:=0 to ObjSymbolList.Count-1 do
begin
objsym:=TObjSymbol(ObjSymbolList[i]);
if (objsym.bind=AB_LOCAL) and (objsym.typ<>AT_LABEL) then
symtabsect.WriteSymbol(objsym);
end;
{ Global Symbols }
for i:=0 to ObjSymbolList.Count-1 do
begin
objsym:=TObjSymbol(ObjSymbolList[i]);
if (objsym.bind<>AB_LOCAL) then
symtabsect.WriteSymbol(objsym);
end;
{ update the .symtab section header }
symtabsect.shlink:=symtabsect.fstrsec.index;
end;
end;
procedure TElfObjectOutput.createshstrtab(data: TObjData);
var
i,prefixlen:longint;
objsec,target:TElfObjSection;
begin
shstrtabsect.writezeros(1);
prefixlen:=length('.rel')+ord(ElfTarget.relocs_use_addend);
for i:=0 to data.ObjSectionList.Count-1 do
begin
objsec:=TElfObjSection(data.ObjSectionList[i]);
{ Alias section names into names of corresponding reloc sections,
this is allowed by ELF specs and saves good half of .shstrtab space. }
if objsec.shtype=relsec_shtype[ElfTarget.relocs_use_addend] then
begin
target:=TElfObjSection(data.ObjSectionList[objsec.shinfo-1]);
if (target.ObjRelocations.Count=0) or
(target.shstridx<prefixlen) then
InternalError(2012101204);
objsec.shstridx:=target.shstridx-prefixlen;
end
else
begin
if objsec.ObjRelocations.Count<>0 then
shstrtabsect.write(relsec_prefix[true][1],prefixlen);
objsec.shstridx:=shstrtabsect.writestr(objsec.name);
end;
end;
end;
procedure TElfObjectOutput.writesectionheader(s:TElfObjSection);
var
sechdr : telfsechdr;
begin
fillchar(sechdr,sizeof(sechdr),0);
sechdr.sh_name:=s.shstridx;
sechdr.sh_type:=s.shtype;
sechdr.sh_flags:=s.shflags;
sechdr.sh_offset:=s.datapos;
sechdr.sh_size:=s.Size;
sechdr.sh_link:=s.shlink;
sechdr.sh_info:=s.shinfo;
sechdr.sh_addralign:=s.secalign;
sechdr.sh_entsize:=s.shentsize;
MaybeSwapSecHeader(sechdr);
writer.write(sechdr,sizeof(sechdr));
end;
procedure TElfObjectOutput.section_count_sections(p:TObject;arg:pointer);
begin
TElfObjSection(p).index:=pword(arg)^;
inc(pword(arg)^);
end;
procedure TElfObjectOutput.section_create_relocsec(p:TObject;arg:pointer);
begin
if (TElfObjSection(p).ObjRelocations.count>0) then
createrelocsection(TElfObjSection(p),TObjData(arg));
end;
procedure TElfObjectOutput.section_write_sechdr(p:TObject;arg:pointer);
begin
writesectionheader(TElfObjSection(p));
end;
function TElfObjectOutput.writedata(data:TObjData):boolean;
var
header : telfheader;
shoffset,
datapos : aword;
nsections : word;
begin
result:=false;
with data do
begin
{ default sections }
symtabsect:=TElfSymtab.create(data,esk_obj);
shstrtabsect:=TElfObjSection.create_ext(data,'.shstrtab',SHT_STRTAB,0,1,0);
{ "no executable stack" marker }
{ TODO: used by OpenBSD/NetBSD as well? }
if (target_info.system in (systems_linux + systems_android + systems_freebsd + systems_dragonfly)) and
not(cs_executable_stack in current_settings.moduleswitches) then
TElfObjSection.create_ext(data,'.note.GNU-stack',SHT_PROGBITS,0,1,0);
{ symbol for filename }
symtabsect.fstrsec.writestr(ExtractFileName(current_module.mainsource));
symtabsect.writeInternalSymbol(0,1,STT_FILE,SHN_ABS);
{ calc amount of sections we have }
nsections:=1;
{ also create the index in the section header table }
ObjSectionList.ForEachCall(@section_count_sections,@nsections);
{ create .symtab and .strtab }
createsymtab(data);
{ Create the relocation sections, this needs valid secidx and symidx }
ObjSectionList.ForEachCall(@section_create_relocsec,data);
{ recalc nsections to incude the reloc sections }
nsections:=1;
ObjSectionList.ForEachCall(@section_count_sections,@nsections);
{ create .shstrtab }
createshstrtab(data);
{ Calculate the filepositions }
datapos:=$40; { elfheader + alignment }
{ section data }
layoutsections(datapos);
{ section headers }
shoffset:=align(datapos,dword(Sizeof(AInt)));
inc(datapos,(nsections+1)*sizeof(telfsechdr));
{ Write ELF Header }
fillchar(header,sizeof(header),0);
header.e_ident[EI_MAG0]:=ELFMAG0; { = #127'ELF' }
header.e_ident[EI_MAG1]:=ELFMAG1;
header.e_ident[EI_MAG2]:=ELFMAG2;
header.e_ident[EI_MAG3]:=ELFMAG3;
header.e_ident[EI_CLASS]:=ELFCLASS;
if target_info.endian=endian_big then
header.e_ident[EI_DATA]:=ELFDATA2MSB
else
header.e_ident[EI_DATA]:=ELFDATA2LSB;
header.e_ident[EI_VERSION]:=1;
if target_info.system in systems_openbsd then
header.e_ident[EI_OSABI]:=ELFOSABI_OPENBSD
else if target_info.system in systems_freebsd then
header.e_ident[EI_OSABI]:=ELFOSABI_FREEBSD
else if target_info.system in systems_dragonfly then
header.e_ident[EI_OSABI]:=ELFOSABI_NONE;
header.e_type:=ET_REL;
header.e_machine:=ElfTarget.machine_code;
header.e_version:=1;
header.e_shoff:=shoffset;
header.e_shstrndx:=shstrtabsect.index;
header.e_shnum:=nsections;
header.e_ehsize:=sizeof(telfheader);
header.e_shentsize:=sizeof(telfsechdr);
if assigned(ElfTarget.encodeflags) then
header.e_flags:=ElfTarget.encodeflags();
MaybeSwapHeader(header);
writer.write(header,sizeof(header));
writer.writezeros($40-sizeof(header)); { align }
{ Sections }
WriteSectionContent(data);
{ Align header }
Writer.Writezeros(Align(Writer.Size,Sizeof(AInt))-Writer.Size);
{ section headers, start with an empty header for sh_undef }
writer.writezeros(sizeof(telfsechdr));
ObjSectionList.ForEachCall(@section_write_sechdr,nil);
end;
result:=true;
end;
{****************************************************************************
TELFAssembler
****************************************************************************}
constructor TElfAssembler.Create(info: pasminfo; smart:boolean);
begin
inherited;
CObjOutput:=TElfObjectOutput;
CInternalAr:=tarobjectwriter;
end;
{****************************************************************************
TELFObjectInput
****************************************************************************}
constructor TElfObjInput.Create;
begin
inherited Create;
CObjData:=TElfObjData;
CObjSymbol:=TObjSymbol;
end;
destructor TElfObjInput.Destroy;
begin
if Assigned(FSymTbl) then
FreeMem(FSymTbl);
if Assigned(FSecTbl) then
FreeMem(FSecTbl);
if Assigned(strtab) then
FreeMem(strtab);
if Assigned(shstrtab) then
FreeMem(shstrtab);
if Assigned(symversions) then
FreeMem(symversions);
inherited Destroy;
end;
procedure TElfObjInput.LoadRelocations(const secrec:TSectionRec);
var
i: longint;
rel: TElfReloc;
reltyp: byte;
relsym: longint;
objrel: TObjRelocation;
p: TObjSymbol;
begin
FReader.Seek(secrec.relocpos);
if secrec.sec=nil then
InternalError(2012060203);
if (secrec.relentsize=3*sizeof(pint)) then
with secrec.sec do SecOptions:=SecOptions+[oso_rela_relocs];
for i:=0 to secrec.relocs-1 do
begin
FReader.Read(rel,secrec.relentsize);
MaybeSwapElfReloc(rel);
reltyp:=rel.info and $FF;
{$ifdef cpu64bitaddr}
relsym:=rel.info shr 32;
{$else cpu64bitaddr}
relsym:=(rel.info shr 8) and $FFFFFF;
{$endif cpu64bitaddr}
if relsym>=syms then
InternalError(2012060204);
p:=TObjSymbol(FSymTbl[relsym]);
{ Some relocations (e.g. R_ARM_V4BX) don't use a symbol at all }
if assigned(p) or (relsym=0) then
begin
objrel:=TObjRelocation.CreateRaw(rel.address-secrec.sec.mempos,p,reltyp);
if (secrec.relentsize=3*sizeof(pint)) then
objrel.orgsize:=rel.addend;
{ perform target-specific actions }
if Assigned(ElfTarget.loadreloc) then
ElfTarget.loadreloc(objrel);
secrec.sec.ObjRelocations.add(objrel);
end
else
begin
InputError('Unable to resolve symbol of relocation');
exit;
end;
end;
end;
procedure TElfObjInput.LoadSymbols(objdata:TObjData;count,locals:longword);
var
i: longint;
sym: TElfSymbol;
bind: TAsmSymBind;
typ: TAsmSymType;
objsym: TObjSymbol;
ver: word;
begin
FSymTbl:=AllocMem(count*sizeof(Pointer));
for i:=1 to count-1 do
begin
FReader.Read(sym,sizeof(TElfSymbol));
MaybeSwapElfSymbol(sym);
if sym.st_name>=strtablen then
InternalError(2012060205);
if sym.st_shndx=SHN_ABS then { ignore absolute symbols (should we really do it???) }
Continue
else if sym.st_shndx=SHN_COMMON then
bind:=AB_COMMON
else if (sym.st_shndx>=nsects) then
InternalError(2012060206)
else
case (sym.st_info shr 4) of
STB_LOCAL:
bind:=AB_LOCAL;
STB_GLOBAL:
if sym.st_shndx=SHN_UNDEF then
bind:=AB_EXTERNAL
else
bind:=AB_GLOBAL;
STB_WEAK:
bind:=AB_WEAK_EXTERNAL;
else
InternalError(2012060207);
end;
{ Ignore section symbol if we didn't create the corresponding objsection
(examples are SHT_GROUP or .note.GNU-stack sections). }
if (sym.st_shndx>0) and (sym.st_shndx<SHN_LORESERVE) and
(FSecTbl[sym.st_shndx].sec=nil) and
(not dynobj) then
if ((sym.st_info and $0F)=STT_SECTION) then
Continue
else
begin
writeln(objdata.name,' ',i);
InternalError(2012110701)
end;
case (sym.st_info and $0F) of
STT_NOTYPE:
typ:=AT_NONE;
STT_OBJECT:
typ:=AT_DATA;
STT_FUNC:
typ:=AT_FUNCTION;
STT_SECTION:
typ:=AT_SECTION;
STT_FILE:
continue;
STT_TLS:
typ:=AT_TLS;
STT_GNU_IFUNC:
typ:=AT_GNU_IFUNC;
else
writeln(objdata.name,' ',sym.st_info and $0F);
InternalError(2012060208);
end;
{ If reading DSO, we're interested only in global symbols defined there.
Symbols with non-current version should also be ignored. }
ver:=0;
if dynobj then
begin
if assigned(symversions) then
begin
ver:=symversions[i];
if (ver=VER_NDX_LOCAL) or (ver>VERSYM_VERSION) then
continue;
end;
if (bind=AB_LOCAL) or (sym.st_shndx=SHN_UNDEF) then
continue;
if ver>=verdefs.count then
InternalError(2012120505);
end;
{ validity of name and objsection has been checked above }
{ !! all AT_SECTION symbols have duplicate (null) name,
therefore TObjSection.CreateSymbol cannot be used here }
objsym:=CObjSymbol.Create(objdata.ObjSymbolList,string(PChar(@strtab[sym.st_name])));
objsym.bind:=bind;
objsym.typ:=typ;
if bind<>AB_COMMON then
objsym.objsection:=FSecTbl[sym.st_shndx].sec;
objsym.offset:=sym.st_value;
objsym.size:=sym.st_size;
FSymTbl[i]:=objsym;
if (ver>VER_NDX_GLOBAL) then
TVersionedObjSymbol(objsym).version:=TElfVersionDef(verdefs[ver]);
end;
end;
function TElfObjInput.CreateSection(const shdr:TElfsechdr;index:longint;objdata:tobjdata;
out secname:string):TElfObjSection;
begin
secname:=string(PChar(@shstrtab[shdr.sh_name]));
result:=TElfObjSection.create_ext(objdata,secname,
shdr.sh_type,shdr.sh_flags,shdr.sh_addralign,shdr.sh_entsize);
result.index:=index;
result.DataPos:=shdr.sh_offset;
result.MemPos:=shdr.sh_addr;
result.Size:=shdr.sh_size;
FSecTbl[index].sec:=result;
end;
function TElfObjInput.ReadBytes(offs:longint;out buf;len:longint):boolean;
begin
FReader.Seek(offs);
result:=FReader.Read(buf,len);
end;
procedure TElfObjInput.LoadSection(const shdr:TElfsechdr;index:longint;objdata:tobjdata);
var
sec: TElfObjSection;
sym: TElfSymbol;
secname: string;
begin
if shdr.sh_name>=shstrtablen then
InternalError(2012060210);
case shdr.sh_type of
SHT_NULL:
{ignore};
{ SHT_STRTAB may appear for .stabstr and other debug sections.
.shstrtab and .strtab are processed separately and don't appear here. }
SHT_PROGBITS,SHT_NOBITS,SHT_NOTE,SHT_STRTAB,
SHT_INIT_ARRAY,SHT_FINI_ARRAY,SHT_PREINIT_ARRAY:
begin
sec:=CreateSection(shdr,index,objdata,secname);
if (Length(secname)>3) and (secname[2] in ['d','f','n','s']) then
begin
if (Pos('.stub',secname)=1) or
(Pos('.fpc',secname)=1) then
sec.SecOptions:=[oso_keep]
{ ELF does not have any flags specific to debug sections,
but reserves names starting with '.debug' for this purpose }
else if (Pos('.debug',secname)=1) or
(secname='.stab') or
(secname='.stabstr') then
sec.SecOptions:=[oso_debug]
else if (secname='.note.GNU-stack') and (shdr.sh_type=SHT_PROGBITS) then
begin
if (shdr.sh_flags and SHF_EXECINSTR)=0 then
objdata.ExecStack:=False;
end;
end;
if (shdr.sh_type=SHT_NOTE) and (shdr.sh_size<>0) then
sec.SecOptions:=[oso_keep];
end;
SHT_REL,SHT_RELA:
begin
if shdr.sh_info>=nsects then
InternalError(2012060211);
if shdr.sh_entsize<>longword((2+ord(shdr.sh_type=SHT_RELA))*sizeof(pint)) then
InternalError(2012060212);
with FSecTbl[shdr.sh_info] do
begin
relocpos:=shdr.sh_offset;
relocs:=shdr.sh_size div shdr.sh_entsize;
relentsize:=shdr.sh_entsize;
end;
end;
SHT_GROUP:
if (shdr.sh_size>=2*sizeof(longword)) and
(shdr.sh_entsize=sizeof(longword)) and
((shdr.sh_size mod shdr.sh_entsize)=0) then
begin
{ Groups are identified by name of symbol pointed to by
sh_link and sh_info, not by sh_name. This symbol
may as well be STT_SECTION symbol of this section,
in which case we end up using sh_name. }
if dynobj then
InternalError(2012110801);
if (shdr.sh_link<>symtabndx) then
InternalError(2012110703);
if (shdr.sh_info>=syms) then
InternalError(2012110704);
FReader.Seek(symtaboffset+shdr.sh_info*sizeof(TElfSymbol));
FReader.Read(sym,sizeof(TElfSymbol));
MaybeSwapElfSymbol(sym);
if sym.st_name>=strtablen then
InternalError(2012110705);
if (sym.st_shndx=index) and (sym.st_info=((STB_LOCAL shl 4) or STT_SECTION)) then
secname:=string(PChar(@shstrtab[shdr.sh_name]))
else
secname:=string(PChar(@strtab[sym.st_name]));
{ Postpone further processing until all sections are loaded,
we'll need to access correct section header.
Since ABI requires SHT_GROUP sections to come first in the file,
we assume that group number x has header index x+1.
If we ever encounter files where this is not true, we'll have
to maintain a separate index. }
objdata.CreateSectionGroup(secname);
if (index<>objdata.GroupsList.Count) then
InternalError(2012110802);
end
else
InternalError(2012110706);
SHT_GNU_ATTRIBUTES:
{ TODO: must not be ignored };
else
if not (assigned(ElfTarget.loadsection) and
ElfTarget.loadsection(self,objdata,shdr,index)) then
InternalError(2012072603);
end;
FLoaded[index]:=True;
end;
function TElfObjInput.LoadHeader(out objdata:TObjData):boolean;
var
header:TElfHeader;
begin
result:=false;
if not FReader.read(header,sizeof(header)) then
begin
InputError('Can''t read ELF header');
exit;
end;
if (header.e_ident[EI_MAG0]<>ELFMAG0) or (header.e_ident[EI_MAG1]<>ELFMAG1) or
(header.e_ident[EI_MAG2]<>ELFMAG2) or (header.e_ident[EI_MAG3]<>ELFMAG3) then
begin
InputError('Illegal ELF magic');
exit;
end;
if (header.e_ident[EI_VERSION]<>1) then
begin
InputError('Unknown ELF file version');
exit;
end;
if (header.e_ident[EI_CLASS]<>ELFCLASS) then
begin
InputError('Wrong ELF file class (32/64 bit mismatch)');
exit;
end;
if (header.e_ident[EI_DATA]<>1+ord(target_info.endian=endian_big)) then
begin
InputError('ELF endianness does not match target');
exit;
end;
MaybeSwapHeader(header);
if (header.e_version<>1) then
begin
InputError('Unknown ELF data version');
exit;
end;
if (header.e_machine<>ElfTarget.machine_code) then
begin
InputError('ELF file is for different CPU');
exit;
end;
if (header.e_type<>ET_REL) and (header.e_type<>ET_DYN) then
begin
InputError('Not a relocatable or dynamic ELF file');
exit;
end;
if header.e_shentsize<>sizeof(TElfsechdr) then
InternalError(2012062701);
nsects:=header.e_shnum;
dynobj:=(header.e_type=ET_DYN);
shoffset:=header.e_shoff;
shstrndx:=header.e_shstrndx;
if dynobj then
begin
objdata:=TElfDynamicObjData.Create(InputFilename);
verdefs:=TElfDynamicObjData(objdata).versiondefs;
CObjSymbol:=TVersionedObjSymbol;
end
else
objdata:=CObjData.Create(InputFilename);
TElfObjData(objdata).ident:=header.e_ident;
TElfObjData(objdata).flags:=header.e_flags;
result:=true;
end;
procedure TElfObjInput.LoadDynamic(const shdr:TElfsechdr;objdata:TObjData);
var
dt: TElfDyn;
i: longint;
begin
if (shdr.sh_entsize<>sizeof(TElfDyn)) then
InternalError(2012071403);
FReader.Seek(shdr.sh_offset);
for i:=0 to (shdr.sh_size div shdr.sh_entsize)-1 do
begin
FReader.Read(dt,sizeof(TElfDyn));
MaybeSwapElfDyn(dt);
case dt.d_tag of
DT_NULL:
break;
DT_SONAME:
TElfObjData(objdata).FName:=string(PChar(@strtab[dt.d_ptr]));
DT_NEEDED:
;
end;
end;
end;
function TElfObjInput.ReadObjData(AReader:TObjectreader;out objdata:TObjData):boolean;
var
i,j,strndx,dynndx,
versymndx,verdefndx,verneedndx: longint;
objsec: TObjSection;
grp: TObjSectionGroup;
tmp: longword;
count: longint;
vd: TElfverdef;
vda: TElfverdaux;
vdoffset: aword;
begin
FReader:=AReader;
InputFileName:=AReader.FileName;
result:=false;
strndx:=0;
if not LoadHeader(objData) then
exit;
FSecTbl:=AllocMem(nsects*sizeof(TSectionRec));
FLoaded:=AllocMem(nsects*sizeof(boolean));
SetLength(shdrs,nsects);
FReader.Seek(shoffset);
if not FReader.Read(shdrs[0],nsects*sizeof(TElfsechdr)) then
begin
InputError('Can''t read ELF section headers');
exit;
end;
if source_info.endian<>target_info.endian then
for i:=0 to nsects-1 do
MaybeSwapSecHeader(shdrs[i]);
{ First, load the .shstrtab section }
if shstrndx>=nsects then
InternalError(2012060201);
if shdrs[shstrndx].sh_type<>SHT_STRTAB then
InternalError(2012060202);
shstrtablen:=shdrs[shstrndx].sh_size;
GetMem(shstrtab,shstrtablen);
FReader.seek(shdrs[shstrndx].sh_offset);
FReader.read(shstrtab^,shstrtablen);
FLoaded[shstrndx]:=True;
{ Locate the symtable, it is typically at the end so loop backwards.
Load the strings, postpone symtable itself until done with sections.
Note that is is legal to have no symtable.
For DSO, locate .dynsym instead, this one is near the beginning, but
overall number of sections won't be big. }
symtabndx:=0;
for i:=nsects-1 downto 1 do
begin
if (shdrs[i].sh_type<>symsectypes[dynobj]) then
continue;
if (shdrs[i].sh_entsize<>sizeof(TElfSymbol)) then
InternalError(2012060213);
if shdrs[i].sh_link>=nsects then
InternalError(2012062702);
strndx:=shdrs[i].sh_link;
if shdrs[strndx].sh_type<>SHT_STRTAB then
InternalError(2012062703);
strtablen:=shdrs[strndx].sh_size;
GetMem(strtab,strtablen);
FReader.seek(shdrs[strndx].sh_offset);
FReader.read(strtab^,strtablen);
symtaboffset:=shdrs[i].sh_offset;
syms:=shdrs[i].sh_size div sizeof(TElfSymbol);
localsyms:=shdrs[i].sh_info;
FLoaded[i]:=True;
FLoaded[strndx]:=True;
symtabndx:=i;
break;
end;
if dynobj then
begin
if symtabndx=0 then
InternalError(2012110707);
{ Locate .dynamic and version sections. Expect a single one of a kind. }
dynndx:=0;
versymndx:=0;
verdefndx:=0;
verneedndx:=0;
for i:=nsects-1 downto 0 do
begin
case shdrs[i].sh_type of
SHT_DYNAMIC:
begin
if dynndx<>0 then
InternalError(2012102001);
dynndx:=i;
if (shdrs[dynndx].sh_link<>strndx) then
InternalError(2012071402);
LoadDynamic(shdrs[dynndx],objdata);
end;
SHT_GNU_versym:
begin
if versymndx<>0 then
InternalError(2012102002);
versymndx:=i;
if shdrs[i].sh_entsize<>sizeof(word) then
InternalError(2012102003);
if shdrs[i].sh_link<>symtabndx then
InternalError(2012102004);
if shdrs[i].sh_size<>syms*sizeof(word) then
InternalError(2012102005);
GetMem(symversions,shdrs[i].sh_size);
FReader.seek(shdrs[i].sh_offset);
FReader.read(symversions^,shdrs[i].sh_size);
if source_info.endian<>target_info.endian then
for j:=0 to syms-1 do
symversions[j]:=SwapEndian(symversions[j]);
end;
SHT_GNU_verdef:
begin
if verdefndx<>0 then
InternalError(2012102006);
verdefndx:=i;
if shdrs[i].sh_link<>strndx then
InternalError(2012120501);
vdoffset:=shdrs[i].sh_offset;
{ TODO: can we rely on sh_info, or must read until vd_next=0? }
for j:=1 to shdrs[i].sh_info do
begin
FReader.seek(vdoffset);
FReader.Read(vd,sizeof(TElfverdef));
MaybeSwapElfverdef(vd);
if vd.vd_version<>VER_DEF_CURRENT then
InternalError(2012120502);
FReader.seek(vdoffset+vd.vd_aux);
vdoffset:=vdoffset+vd.vd_next;
{ First verdaux entry holds name of version (unless VER_FLG_BASE flag is set),
subsequent one(s) point to parent(s). For our purposes, version hierarchy
looks irrelevant. }
FReader.Read(vda,sizeof(TElfverdaux));
MaybeSwapElfverdaux(vda);
if vda.vda_name>=strtablen then
InternalError(2012120503);
if (vd.vd_flags and VER_FLG_BASE)<>0 then
continue;
{ Assuming verdef indices assigned continuously starting from 2,
at least BFD produces files that way. }
if verdefs.count<>vd.vd_ndx then
InternalError(2012120504);
TElfVersionDef.Create(verdefs,string(PChar(@strtab[vda.vda_name])));
end;
end;
SHT_GNU_verneed:
begin
if verneedndx<>0 then
InternalError(2012102007);
verneedndx:=i;
//sh_link->.dynstr
//sh_info->number of entries
end;
end;
end;
if dynndx=0 then
InternalError(2012071401);
{ load the symtable }
FReader.Seek(symtaboffset+sizeof(TElfSymbol));
LoadSymbols(objdata,syms,localsyms);
result:=True;
exit;
end;
{ assume stack is executable until proven otherwise }
objdata.ExecStack:=True;
{ Process section headers }
for i:=1 to nsects-1 do
if not FLoaded[i] then
LoadSection(shdrs[i],i,objdata);
{ load the content }
ReadSectionContent(objdata);
{ load the symtable }
FReader.Seek(symtaboffset+sizeof(TElfSymbol));
LoadSymbols(objdata,syms,localsyms);
{ finish relocations }
for i:=0 to objdata.ObjSectionList.Count-1 do
begin
objsec:=TObjSection(objdata.ObjsectionList[i]);
{ skip debug sections }
if (oso_debug in objsec.SecOptions) and
(cs_link_strip in current_settings.globalswitches) and
not(cs_link_separate_dbg_file in current_settings.globalswitches) then
continue;
if FSecTbl[objsec.index].relocpos>0 then
LoadRelocations(FSecTbl[objsec.index]);
end;
{ finish processing section groups, if any }
if Assigned(objdata.GroupsList) then
begin
for i:=0 to objdata.GroupsList.Count-1 do
begin
grp:=TObjSectionGroup(objData.GroupsList[i]);
FReader.Seek(shdrs[i+1].sh_offset);
{ first dword is flags }
FReader.Read(tmp,sizeof(longword));
if source_info.endian<>target_info.endian then
tmp:=SwapEndian(tmp);
if (tmp and GRP_COMDAT)<>0 then
grp.IsComdat:=true;
count:=(shdrs[i+1].sh_size div sizeof(longword))-1;
SetLength(grp.members,count);
for j:=0 to count-1 do
begin
FReader.Read(tmp,sizeof(longword));
if source_info.endian<>target_info.endian then
tmp:=SwapEndian(tmp);
if (tmp>=nsects) then
InternalError(2012110805);
objsec:=FSecTbl[tmp].sec;
if (objsec=nil) then
InternalError(2012110806);
if (TElfObjSection(objsec).shflags and SHF_GROUP)=0 then
InternalError(2012110807);
grp.members[j]:=objsec;
objsec.Group:=grp;
end;
end;
end;
result:=True;
end;
class function TElfObjInput.CanReadObjData(AReader:TObjectreader):boolean;
var
header: TElfHeader;
begin
result:=false;
if AReader.Read(header,sizeof(header)) then
begin;
if (header.e_ident[EI_MAG0]=ELFMAG0) and (header.e_ident[EI_MAG1]=ELFMAG1) and
(header.e_ident[EI_MAG2]=ELFMAG2) and (header.e_ident[EI_MAG3]=ELFMAG3) then
{ TODO: check additional fields }
result:=true;
end;
AReader.Seek(0);
end;
{*****************************************************************************
TElfExeOutput
*****************************************************************************}
constructor TElfExeOutput.Create;
begin
inherited Create;
CObjData:=TElfObjData;
CExeSection:=TElfExeSection;
{$ifdef cpu64}
MaxMemPos:=Qword($FFFFFFFFFFFFFFFF);
//MaxMemPos:=$7EFFFFFF; { As specified by SysV AMD64 ABI for small memory model }
{$else cpu64}
MaxMemPos:=$7FFFFFFF;
{$endif cpu64}
SectionMemAlign:=$20;
SectionDataAlign:=$20;
segmentlist:=TFPObjectList.Create(True);
neededlist:=TFPHashList.Create;
end;
destructor TElfExeOutput.Destroy;
begin
dyncopysyms.Free;
neededlist.Free;
segmentlist.Free;
dynsymlist.Free;
dynreloclist.Free;
if assigned(dynsymnames) then
FreeMem(dynsymnames);
stringdispose(FInterpreter);
inherited Destroy;
end;
function TElfExeOutput.AttachSection(objsec:TObjSection):TElfExeSection;
begin
objsec.SecOptions:=[oso_keep];
result:=TElfExeSection(FindExeSection(objsec.name));
if result=nil then
result:=TElfExeSection.Create(ExeSectionList,objsec.name);
result.AddObjSection(objsec);
end;
function TElfExeOutput.CreateSegment(atype,aflags,aalign:longword):TElfSegment;
begin
result:=TElfSegment.Create(atype,aflags,aalign);
segmentlist.add(result);
end;
procedure TElfExeOutput.WriteHeader;
var
header: TElfHeader;
begin
FillChar(header,sizeof(header),0);
header.e_ident[EI_MAG0]:=ELFMAG0; { = #127'ELF' }
header.e_ident[EI_MAG1]:=ELFMAG1;
header.e_ident[EI_MAG2]:=ELFMAG2;
header.e_ident[EI_MAG3]:=ELFMAG3;
header.e_ident[EI_CLASS]:=ELFCLASS;
if target_info.endian=endian_big then
header.e_ident[EI_DATA]:=ELFDATA2MSB
else
header.e_ident[EI_DATA]:=ELFDATA2LSB;
header.e_ident[EI_VERSION]:=1;
if target_info.system in systems_openbsd then
header.e_ident[EI_OSABI]:=ELFOSABI_OPENBSD
else if target_info.system in systems_freebsd then
header.e_ident[EI_OSABI]:=ELFOSABI_FREEBSD
else if target_info.system in systems_dragonfly then
header.e_ident[EI_OSABI]:=ELFOSABI_NONE;
if IsSharedLibrary then
header.e_type:=ET_DYN
else
header.e_type:=ET_EXEC;
header.e_machine:=ElfTarget.machine_code;
header.e_version:=1;
header.e_phoff:=sizeof(TElfHeader);
header.e_shoff:=shoffset;
header.e_shstrndx:=ExeSectionList.IndexOf(shstrtabsect.ExeSection)+1;
header.e_shnum:=ExeSectionList.Count+1;
header.e_phnum:=segmentlist.count;
header.e_ehsize:=sizeof(telfheader);
if assigned(ElfTarget.encodeflags) then
header.e_flags:=ElfTarget.encodeflags();
if assigned(EntrySym) then
header.e_entry:=EntrySym.Address;
header.e_shentsize:=sizeof(telfsechdr);
header.e_phentsize:=sizeof(telfproghdr);
MaybeSwapHeader(header);
FWriter.Write(header,sizeof(header));
end;
procedure TElfExeOutput.exesection_write_header(p:TObject;arg:Pointer);
var
shdr: TElfsechdr;
exesec: TElfExeSection absolute p;
begin
FillChar(shdr,sizeof(shdr),0);
shdr.sh_name:=exesec.shstridx;
if (ExeWriteMode=ewm_dbgonly) and
(exesec.SecOptions*[oso_debug,oso_debug_copy]=[]) then
shdr.sh_type:=SHT_NOBITS
else
shdr.sh_type:=exesec.shtype;
shdr.sh_flags:=exesec.shflags;
if (oso_load in exesec.SecOptions) then
shdr.sh_addr:=exesec.MemPos;
shdr.sh_offset:=exesec.DataPos;
shdr.sh_size:=exesec.Size;
shdr.sh_link:=exesec.shlink;
shdr.sh_info:=exesec.shinfo;
shdr.sh_addralign:=exesec.SecAlign;
shdr.sh_entsize:=exesec.shentsize;
MaybeSwapSecHeader(shdr);
FWriter.Write(shdr,sizeof(shdr));
end;
procedure TElfExeOutput.segment_write_header(p:TObject;arg:Pointer);
var
phdr: TElfproghdr;
seg: TElfSegment absolute p;
begin
FillChar(phdr,sizeof(phdr),0);
phdr.p_type:=seg.ptype;
phdr.p_flags:=seg.pflags;
phdr.p_align:=seg.align;
phdr.p_offset:=seg.DataPos;
phdr.p_filesz:=seg.DataSize;
phdr.p_memsz:=seg.MemSize;
phdr.p_vaddr:=seg.MemPos;
phdr.p_paddr:=seg.MemPos;
MaybeSwapHeader(phdr);
FWriter.Write(phdr,sizeof(phdr));
end;
procedure TElfExeOutput.WriteStaticSymtable;
var
i: longint;
sec: TElfExeSection;
exesym: TExeSymbol;
begin
if assigned(tlsseg) then
symtab.tlsbase:=tlsseg.MemPos;
for i:=0 to ExeSectionList.Count-1 do
begin
sec:=TElfExeSection(ExeSectionList[i]);
{ Must not write symbols for internal sections like .symtab }
if (sec.shtype in [SHT_SYMTAB,SHT_STRTAB,SHT_REL,SHT_RELA]) then
continue;
sec.secsymidx:=symtab.symidx;
symtab.writeInternalSymbol(sec.mempos,0,STT_SECTION,sec.secshidx);
end;
{ local symbols first }
for i:=0 to ExeSymbolList.Count-1 do
begin
exesym:=TExeSymbol(ExeSymbolList[i]);
if (exesym.objsymbol.bind=AB_LOCAL) and (exesym.objsymbol.typ<>AT_LABEL) then
symtab.WriteSymbol(exesym.objsymbol);
end;
{ Global Symbols }
for i:=0 to ExeSymbolList.Count-1 do
begin
exesym:=TExeSymbol(ExeSymbolList[i]);
if (exesym.objsymbol.bind<>AB_LOCAL) then
symtab.WriteSymbol(exesym.objsymbol);
end;
{ update exe section properties }
symtab.ExeSection.size:=symtab.size;
TElfExeSection(symtab.ExeSection).shinfo:=symtab.shinfo;
TElfExeSection(symtab.ExeSection).shlink:=ExeSectionList.IndexOf(symtab.fstrsec.ExeSection)+1;
symtab.fstrsec.ExeSection.Size:=symtab.fstrsec.size;
end;
procedure TElfExeOutput.MapSectionsToSegments;
var
seg: TElfSegment;
exesec: TExeSection;
i: longint;
begin
if (not IsSharedLibrary) and assigned(interpobjsec) then
begin
phdrseg:=CreateSegment(PT_PHDR,PF_R or PF_X,sizeof(pint));
seg:=CreateSegment(PT_INTERP,PF_R,1);
seg.Add(interpobjsec.ExeSection);
end;
textseg:=CreateSegment(PT_LOAD,PF_X or PF_R,ElfTarget.max_page_size);
dataseg:=CreateSegment(PT_LOAD,PF_R or PF_W,ElfTarget.max_page_size);
for i:=0 to ExeSectionList.Count-1 do
begin
exesec:=TExeSection(ExeSectionList[i]);
if (oso_load in exesec.SecOptions) then
begin
if (TElfExeSection(exesec).shflags and SHF_TLS)<>0 then
begin
if tlsseg=nil then
tlsseg:=CreateSegment(PT_TLS,PF_R,sizeof(pint));
tlsseg.add(exesec);
end;
{ TODO: at least on Linux, ld seems to drop .note.ABI-tag for static executables.
(Logic is as follows: there is no .note.ABI-tag section in ld script, so it
is processed as orphan section. As such, it is placed after .interp.
For static executables .interp is dropped, and it looks like there's nowhere to
place .note.ABI-tag in this case)
Always including it doesn't harm though (except increasing file size). }
if TElfExeSection(exesec).shtype=SHT_NOTE then
begin
if noteseg=nil then
noteseg:=CreateSegment(PT_NOTE,PF_R,4);
noteseg.Add(exesec);
Include(exesec.SecOptions,oso_debug_copy);
end;
if (oso_executable in exesec.SecOptions) or
not (oso_write in exesec.SecOptions) then
textseg.add(exesec)
else
dataseg.add(exesec);
end;
end;
if dynamiclink then
begin
seg:=CreateSegment(PT_DYNAMIC,PF_R or PF_W,sizeof(pint));
seg.add(dynamicsec.ExeSection);
end;
{ stack flags }
CreateSegment(PT_GNU_STACK,PF_R or PF_W or (PF_X*ord(ExecStack)),sizeof(pint));
end;
procedure TElfExeOutput.make_dynamic_if_undefweak(exesym:TExeSymbol);
begin
if (exesym.dynindex=0) and (exesym.state=symstate_undefweak) and
not (cs_link_staticflag in current_settings.globalswitches) then
exesym.dynindex:=dynsymlist.add(exesym)+1;
end;
function TElfExeOutput.AllocGOTSlot(objsym:TObjSymbol):boolean;
var
exesym: TExeSymbol;
begin
result:=false;
exesym:=objsym.exesymbol;
{ Although local symbols should not be accessed through GOT,
this isn't strictly forbidden. In this case we need to fake up
the exesym to store the GOT offset in it.
TODO: name collision; maybe use a different symbol list object? }
if exesym=nil then
begin
exesym:=TExeSymbol.Create(ExeSymbolList,objsym.name+'*local*');
exesym.objsymbol:=objsym;
objsym.exesymbol:=exesym;
end;
if exesym.GotOffset>0 then
exit;
gotobjsec.alloc(sizeof(pint));
exesym.GotOffset:=gotobjsec.size;
make_dynamic_if_undefweak(exesym);
{ In shared library, every GOT entry needs a RELATIVE dynamic reloc,
imported/exported symbols need GLOB_DAT instead. For executables,
only the latter applies. }
if IsSharedLibrary or (exesym.dynindex>0) then
dynrelocsec.alloc(dynrelocsec.shentsize);
result:=true;
end;
procedure TElfExeOutput.PrepareGOT;
var
i,j,k: longint;
objsec: TElfObjSection;
exesec: TExeSection;
begin
for i:=0 to ExeSectionList.Count-1 do
begin
exesec:=TExeSection(ExeSectionList[i]);
for j:=0 to exesec.ObjSectionlist.count-1 do
begin
objsec:=TElfObjSection(exesec.ObjSectionlist[j]);
{ ignore linker-generated and debug sections }
if (objsec.objdata=internalobjdata) or (oso_debug in objsec.SecOptions) then
continue;
if not objsec.Used then
internalerror(2012060901);
k:=0;
while k<objsec.ObjRelocations.Count do
begin
GOTRelocPass1(objsec,k);
inc(k);
end;
end;
end;
{ remember sizes for sanity checking }
gotsize:=gotobjsec.size;
if assigned(dynrelocsec) then
dynrelsize:=dynrelocsec.size
else
dynrelsize:=0;
end;
procedure TElfExeOutput.CreateGOTSection;
begin
gotpltobjsec:=TElfObjSection.create_ext(internalObjData,'.got.plt',
SHT_PROGBITS,SHF_ALLOC or SHF_WRITE,sizeof(pint),sizeof(pint));
gotobjsec:=TElfObjSection.create_ext(internalObjData,'.got',
SHT_PROGBITS,SHF_ALLOC or SHF_WRITE,sizeof(pint),sizeof(pint));
gotobjsec.SecOptions:=[oso_keep];
{ GOT symbol and reserved .got.plt entries }
internalObjData.SetSection(gotpltobjsec);
gotsymbol:=internalObjData.SymbolDefine('_GLOBAL_OFFSET_TABLE_',AB_GLOBAL,AT_DATA);
gotpltobjsec.writeZeros(3*sizeof(pint));
end;
procedure TElfExeOutput.Load_Start;
begin
inherited Load_Start;
dynsymlist:=TFPObjectList.Create(False);
CreateGOTSection;
end;
procedure TElfExeOutput.Load_DynamicObject(objdata:TObjData;asneeded:boolean);
var
i: longint;
exesym: TExeSymbol;
objsym: TObjSymbol;
needed: boolean;
begin
Comment(v_debug,'Dynamic object: '+objdata.name);
needed:=false;
for i:=0 to UnresolvedExeSymbols.Count-1 do
begin
exesym:=TExeSymbol(UnresolvedExeSymbols[i]);
if not (exesym.State in [symstate_undefined,symstate_undefweak]) then
continue;
objsym:=TObjSymbol(objdata.ObjSymbolList.Find(exesym.name));
if assigned(objsym) then
begin
exesym.State:=symstate_defined;
exesym.dynindex:=dynsymlist.Add(exesym)+1;
{ The original binding, value and section of external symbol
must be preserved, therefore resolving directly to .so symbol
hurts more than it helps. Copy type and size, and store .so
symbol in objsym.indsymbol for later use. }
exesym.ObjSymbol.typ:=objsym.typ;
if objsym.typ<>AT_FUNCTION then
exesym.ObjSymbol.size:=objsym.size;
exesym.ObjSymbol.indsymbol:=objsym;
objsym.ExeSymbol:=exesym;
needed:=true;
end;
end;
if (needed or (not asneeded)) and
(neededlist.Find(objdata.name)=nil) then
neededlist.Add(objdata.name,objdata);
end;
procedure TElfExeOutput.Order_Start;
begin
inherited Order_Start;
dynamiclink:=IsSharedLibrary or (dynsymlist.count>0) or
(
(UnresolvedExeSymbols.Count>0) and
not (cs_link_staticflag in current_settings.globalswitches)
);
if dynamiclink then
InitDynlink;
if dynamiclink or (IndirectObjSymbols.Count>0) then
CreatePLT;
end;
procedure TElfExeOutput.Order_end;
procedure set_oso_keep(const s:string;out firstsec:TObjSection);
var
exesec:TExeSection;
objsec:TObjSection;
i:longint;
sz: aword;
begin
firstsec:=nil;
sz:=0;
exesec:=TExeSection(ExeSectionList.Find(s));
if assigned(exesec) then
begin
for i:=0 to exesec.ObjSectionList.Count-1 do
begin
objsec:=TObjSection(exesec.ObjSectionList[i]);
{ ignore sections used for symbol definition }
if oso_data in objsec.SecOptions then
begin
if firstsec=nil then
firstsec:=objsec;
objsec.SecOptions:=[oso_keep];
inc(sz,objsec.size);
end;
end;
exesec.size:=sz;
end;
end;
var
dummy: TObjSection;
begin
OrderOrphanSections;
inherited Order_end;
set_oso_keep('.init',dummy);
set_oso_keep('.fini',dummy);
set_oso_keep('.jcr',dummy);
set_oso_keep('.ctors',dummy);
set_oso_keep('.dtors',dummy);
set_oso_keep('.preinit_array',preinitarraysec);
if assigned(preinitarraysec) and IsSharedLibrary then
Comment(v_error,'.preinit_array section is not allowed in shared libraries');
set_oso_keep('.init_array',initarraysec);
set_oso_keep('.fini_array',finiarraysec);
set_oso_keep('.eh_frame',dummy);
{ let .dynamic reference other dynamic sections so they aren't marked
for removal as unused }
if dynamiclink then
WriteDynamicTags;
end;
procedure TElfExeOutput.OrderOrphanSections;
var
i,j:longint;
objdata:TObjData;
objsec:TObjSection;
exesec:TExeSection;
opts:TObjSectionOptions;
s:string;
newsections:TFPHashObjectList;
allsections:TFPList;
inserts:array[0..6] of TExeSection;
idx,inspos:longint;
begin
newsections:=TFPHashObjectList.Create(false);
allsections:=TFPList.Create;
{ copy existing sections }
for i:=0 to ExeSectionList.Count-1 do
allsections.add(ExeSectionList[i]);
inserts[0]:=FindExeSection('.comment');
inserts[1]:=nil;
inserts[2]:=FindExeSection('.interp');
inserts[3]:=FindExeSection('.bss');
inserts[4]:=FindExeSection('.data');
inserts[5]:=FindExeSection('.rodata');
inserts[6]:=FindExeSection('.text');
for i:=0 to ObjDataList.Count-1 do
begin
ObjData:=TObjData(ObjDataList[i]);
for j:=0 to ObjData.ObjSectionList.Count-1 do
begin
objsec:=TObjSection(ObjData.ObjSectionList[j]);
if objsec.Used then
continue;
s:=objsec.name;
exesec:=TExeSection(newsections.Find(s));
if assigned(exesec) then
begin
exesec.AddObjSection(objsec);
continue;
end;
opts:=objsec.SecOptions*[oso_data,oso_load,oso_write,oso_executable];
if (objsec.SecOptions*[oso_load,oso_debug]=[]) then
{ non-alloc, after .comment
GNU ld places .comment between stabs and dwarf debug info }
inspos:=0
else if not (oso_load in objsec.SecOptions) then
inspos:=1 { debugging, skip }
else if (oso_load in objsec.SecOptions) and
(TElfObjSection(objsec).shtype=SHT_NOTE) then
inspos:=2 { after .interp }
else if (opts=[oso_load,oso_write]) then
inspos:=3 { after .bss }
else if (opts=[oso_data,oso_load,oso_write]) then
inspos:=4 { after .data }
else if (opts=[oso_data,oso_load]) then
inspos:=5 { rodata, relocs=??? }
else if (opts=[oso_data,oso_load,oso_executable]) then
inspos:=6 { text }
else
begin
Comment(v_debug,'Orphan section '+objsec.fullname+' has attributes that are not handled!');
continue;
end;
if (inserts[inspos]=nil) then
begin
Comment(v_debug,'Orphan section '+objsec.fullname+': nowhere to insert, ignored');
continue;
end;
idx:=allsections.IndexOf(inserts[inspos]);
exesec:=CExeSection.Create(newsections,s);
allsections.Insert(idx+1,exesec);
inserts[inspos]:=exesec;
exesec.AddObjSection(objsec);
end;
end;
{ Now replace the ExeSectionList with content of allsections }
if (newsections.count<>0) then
ReplaceExeSectionList(allsections);
newsections.Free;
allsections.Free;
end;
procedure TElfExeOutput.AfterUnusedSectionRemoval;
var
i:longint;
exesym:TExeSymbol;
objsym:TObjSymbol;
objsec: TObjSection;
begin
{ Unused section removal sets Used property of referenced exesymbols.
Remaining ones can be removed. }
for i:=0 to dynsymlist.count-1 do
begin
exesym:=TExeSymbol(dynsymlist[i]);
if assigned(exesym.ObjSymbol.ObjSection) then // an exported symbol
continue;
if not exesym.used then
begin
dynsymlist[i]:=nil;
exesym.dynindex:=0;
end;
end;
dynsymlist.Pack;
{ reindex }
for i:=0 to dynsymlist.count-1 do
TExeSymbol(dynsymlist[i]).dynindex:=i+1;
{ Drop unresolved symbols that aren't referenced, assign dynamic
indices to remaining ones, but not if linking with -Xt.
TODO: behavior of .so with -Xt ? }
if (cs_link_staticflag in current_settings.globalswitches) then
UnresolvedExeSymbols.Clear
else
for i:=0 to UnresolvedExeSymbols.Count-1 do
begin
exesym:=TExeSymbol(UnresolvedExeSymbols[i]);
if exesym.used then
begin
if exesym.dynindex<>0 then
InternalError(2012062301);
{ Weak-referenced symbols are changed into dynamic ones
only if referenced through GOT or PLT (this is BFD-compatible) }
if exesym.state<>symstate_undefweak then
exesym.dynindex:=dynsymlist.add(exesym)+1;
end
else
UnresolvedExeSymbols[i]:=nil;
end;
UnresolvedExeSymbols.Pack;
{ Scan relocations to determine size of GOT, dynamic reloc section, etc. }
PrepareGOT;
{ Write required PLT entries }
for i:=0 to dynsymlist.Count-1 do
begin
exesym:=TExeSymbol(dynsymlist[i]);
if assigned(exesym.ObjSymbol.objsection) then // an exported symbol
continue;
if ((exesym.ObjSymbol.refs and symref_plt)<>0) or
((exesym.ObjSymbol.typ in [AT_FUNCTION,AT_GNU_IFUNC]) and (not IsSharedLibrary)) then
begin
make_dynamic_if_undefweak(exesym);
{ This symbol has a valid address to which relocations are resolved,
but it remains (weak)external when written to dynamic symtable. }
objsym:=internalobjdata.CreateSymbol(exesym.name);
objsym.typ:=AT_FUNCTION;
objsym.bind:=exesym.ObjSymbol.bind; { AB_EXTERNAL or AB_WEAK_EXTERNAL }
objsym.indsymbol:=exesym.ObjSymbol.indsymbol;
objsym.offset:=pltobjsec.size;
objsym.objsection:=pltobjsec;
objsym.exesymbol:=exesym;
exesym.ObjSymbol:=objsym;
WritePLTEntry(exesym);
end
else if ((exesym.ObjSymbol.refs and symref_from_text)<>0) and
(exesym.ObjSymbol.typ<>AT_FUNCTION) and (not IsSharedLibrary) and
(exesym.state<>symstate_undefweak) then
begin
if exesym.ObjSymbol.size=0 then
Comment(v_error,'Dynamic variable '+exesym.name+' has zero size');
internalobjdata.setSection(dynbssobjsec);
internalobjdata.allocalign(size_2_align(exesym.ObjSymbol.size));
objsym:=internalobjdata.SymbolDefine(exesym.name,AB_GLOBAL,AT_DATA);
objsym.size:=exesym.ObjSymbol.size;
objsym.indsymbol:=exesym.ObjSymbol.indsymbol;
exesym.ObjSymbol:=objsym;
objsym.exesymbol:=exesym;
dynbssobjsec.alloc(objsym.size);
{ allocate space for R_xx_COPY relocation for this symbol;
we'll create it later, to be consistent with "-z combreloc" semantics }
dyncopysyms.add(objsym);
dynrelocsec.alloc(dynrelocsec.shentsize);
inc(dynrelsize,dynrelocsec.shentsize);
end;
end;
{ Handle indirect symbols }
for i:=0 to IndirectObjSymbols.Count-1 do
begin
objsym:=TObjSymbol(IndirectObjSymbols[i]);
objsec:=objsym.ExeSymbol.ObjSymbol.objsection;
objsym.bind:=AB_EXTERNAL; { cheat FixupSymbols }
if (oso_plt in objsec.SecOptions) then
continue;
WriteIndirectPLTEntry(objsym.ExeSymbol);
end;
FixupSymbols;
if dynamiclink then
begin
WriteVersionSections;
WriteDynamicSymbolsHash;
end;
{ Create .shstrtab section, which is needed in both exe and .dbg files }
shstrtabsect:=TElfObjSection.Create_ext(internalObjData,'.shstrtab',SHT_STRTAB,0,1,0);
shstrtabsect.SecOptions:=[oso_debug_copy];
AttachSection(shstrtabsect);
{ Create the static symtable (.symtab and .strtab) }
if (cs_link_separate_dbg_file in current_settings.globalswitches) or
not(cs_link_strip in current_settings.globalswitches) then
begin
symtab:=TElfSymtab.Create(internalObjData,esk_exe);
symtab.SecOptions:=[oso_debug];
symtab.fstrsec.SecOptions:=[oso_debug];
AttachSection(symtab);
AttachSection(symtab.fstrsec);
end;
{ Re-enable sections which end up to contain some data
(.got, .rel[a].dyn, .rel[a].plt (includes .rel[a].iplt) and .hash }
if gotobjsec.size<>0 then
gotobjsec.ExeSection.Disabled:=false;
if assigned(dynrelocsec) and
((dynrelocsec.size<>0) or (dyncopysyms.count<>0)) then
dynrelocsec.ExeSection.Disabled:=false;
if assigned(pltrelocsec) and (pltrelocsec.size>0) then
pltrelocsec.ExeSection.Disabled:=false;
if assigned(ipltrelocsec) and (ipltrelocsec.size>0) then
ipltrelocsec.ExeSection.Disabled:=false;
if assigned(hashobjsec) then
hashobjsec.ExeSection.Disabled:=false;
if assigned(symversec) and (symversec.size<>0) then
symversec.ExeSection.Disabled:=false;
if assigned(verneedsec) and (verneedsec.size<>0) then
verneedsec.ExeSection.Disabled:=false;
if assigned(verdefsec) and (verdefsec.size<>0) then
verdefsec.ExeSection.Disabled:=false;
RemoveDisabledSections;
MapSectionsToSegments;
if dynamiclink then
FinishDynamicTags;
end;
procedure TElfExeOutput.WriteShStrtab;
var
i: longint;
exesec: TElfExeSection;
begin
{ Remove any existing .shstrtab contents }
if (shstrtabsect.size>0) then
begin
shstrtabsect.ReleaseData;
shstrtabsect.Size:=0;
shstrtabsect.SecOptions:=[oso_data];
end;
shstrtabsect.writezeros(1);
for i:=0 to ExeSectionList.Count-1 do
begin
exesec:=TElfExeSection(ExeSectionList[i]);
exesec.shstridx:=shstrtabsect.writestr(exesec.Name);
exesec.secshidx:=i+1;
end;
end;
procedure TElfExeOutput.FixupSectionLinks;
var
dynstrndx,dynsymndx: longword;
begin
if dynamiclink then
begin
dynstrndx:=TElfExeSection(dynsymtable.fstrsec.ExeSection).secshidx;
dynsymndx:=TElfExeSection(dynsymtable.ExeSection).secshidx;
TElfExeSection(hashobjsec.ExeSection).shlink:=dynsymndx;
TElfExeSection(dynamicsec.ExeSection).shlink:=dynstrndx;
TElfExeSection(dynsymtable.ExeSection).shlink:=dynstrndx;
if assigned(pltrelocsec) then
begin
TElfExeSection(pltrelocsec.ExeSection).shlink:=dynsymndx;
TElfExeSection(pltrelocsec.ExeSection).shinfo:=TElfExeSection(pltobjsec.ExeSection).secshidx;
end;
if assigned(dynrelocsec) and assigned(dynrelocsec.ExeSection) then
TElfExeSection(dynrelocsec.ExeSection).shlink:=dynsymndx;
if symversec.size>0 then
TElfExeSection(symversec.ExeSection).shlink:=dynsymndx;
if verdefsec.size>0 then
TElfExeSection(verdefsec.ExeSection).shlink:=dynstrndx;
if verneedsec.size>0 then
TElfExeSection(verneedsec.ExeSection).shlink:=dynstrndx;
end
else if assigned(ipltrelocsec) then
TElfExeSection(ipltrelocsec.ExeSection).shinfo:=TElfExeSection(pltobjsec.ExeSection).secshidx;
end;
procedure TElfExeOutput.Do_Mempos;
var
i,j: longint;
seg: TElfSegment;
exesec: TElfExeSection;
objsec: TObjSection;
tempmempos: qword;
begin
if IsSharedLibrary then
CurrMemPos:=0
else
CurrMemPos:=ElfTarget.exe_image_base;
textseg.MemPos:=CurrMemPos;
if assigned(phdrseg) then
begin
phdrseg.Mempos:=CurrMemPos+sizeof(TElfHeader);
phdrseg.Memsize:=sizeof(TElfproghdr)*segmentlist.count;
end;
CurrMemPos:=CurrMemPos+sizeof(TElfHeader)+segmentlist.count*sizeof(TElfproghdr);
MemPos_Segment(textseg);
CurrMemPos:=Align(CurrMemPos,SectionDataAlign); {! Data,not MemAlign}
CurrMemPos:=CurrMemPos+ElfTarget.max_page_size;
dataseg.MemPos:=CurrMemPos;
MemPos_Segment(dataseg);
{ Mempos of unmapped sections is forced to zero, but we have to set positions
of its objsections and update sizes }
for i:=0 to ExeSectionList.Count-1 do
begin
exesec:=TElfExeSection(ExeSectionList[i]);
if not (oso_load in exesec.SecOptions) then
begin
tempmempos:=0;
exesec.MemPos:=tempmempos;
for j:=0 to exesec.ObjSectionList.Count-1 do
begin
objsec:=TObjSection(exesec.ObjSectionList[j]);
tempmempos:=objsec.setmempos(tempmempos);
end;
exesec.Size:=tempmempos;
end;
end;
{ Update MemPos and MemSize of non-load segments,
in particular, TLS sizes are needed to resolve relocations }
for i:=0 to segmentlist.count-1 do
begin
seg:=TElfSegment(segmentlist[i]);
if (seg.ptype=PT_LOAD) or (seg.FSectionList.Count=0) then
continue;
seg.MemPos:=TExeSection(seg.FSectionList.First).MemPos;
for j:=0 to seg.FSectionList.Count-1 do
begin
exesec:=TElfExeSection(seg.FSectionList[j]);
seg.MemSize:=exesec.MemPos+exesec.Size-seg.MemPos;
end;
end;
end;
procedure TElfExeOutput.MemPos_Start;
var
i: longint;
begin
{ Assign section indices and fill .shstrtab
List of sections cannot be modified after this point. }
WriteShStrtab;
{ fixup sh_link/sh_info members of various dynamic sections }
FixupSectionLinks;
{ The actual layout }
Do_Mempos;
if (not gotwritten) then
begin
{ Reset size of .got and .rel[a].dyn, they will be refilled while fixing up relocations.
For .got, consider already written reserved entries. }
if assigned(gotobjsec) then
gotobjsec.size:=gotobjsec.data.size;
if assigned(dynrelocsec) then
begin
dynrelocsec.size:=0;
{ write actual .dynsym content (needs valid symbol addresses) }
if assigned(tlsseg) then
dynsymtable.tlsbase:=tlsseg.MemPos;
dynsymtable.size:=sizeof(TElfsymbol);
for i:=0 to dynsymlist.count-1 do
dynsymtable.writeSymbol(TExeSymbol(dynsymlist[i]).objsymbol,dynsymnames[i]);
end;
end;
end;
procedure TElfExeOutput.MemPos_Segment(seg:TElfSegment);
var
i: longint;
exesec: TElfExeSection;
begin
for i:=0 to seg.FSectionList.Count-1 do
begin
exesec:=TElfExeSection(seg.FSectionList[i]);
inherited MemPos_ExeSection(exesec);
{ .tbss should not contribute to address space }
if (exesec.shtype=SHT_NOBITS) and ((exesec.shflags and SHF_TLS)<>0) then
CurrMemPos:=exesec.MemPos;
end;
{ calculate size of the segment }
seg.MemSize:=CurrMemPos-seg.MemPos;
end;
procedure TElfExeOutput.MemPos_ExeSection(const aname:string);
begin
// Ignore. All layout is done in mempos_start
end;
procedure TElfExeOutput.DataPos_Start;
var
i,j: longint;
exesec: TExeSection;
seg: TElfSegment;
objreloc: TObjRelocation;
objsym: TObjSymbol;
begin
gotwritten:=true;
{ If target does not support sorted relocations, it is expected to write the
entire .rel[a].dyn section during FixupRelocations, and leave dynreloclist empty.
Otherwise, only RELATIVE ones should be written, space for non-relative relocations
should remain. }
if assigned(dynrelocsec) then
begin
{ Append R_xx_COPY relocations }
for i:=0 to dyncopysyms.count-1 do
begin
objsym:=TObjSymbol(dyncopysyms[i]);
dynreloclist.Add(TObjRelocation.CreateRaw(objsym.address,objsym,ElfTarget.dyn_reloc_codes[dr_copy]));
end;
dyncopysyms.Clear;
if (dynrelocsec.size+(dynreloclist.count*dynrelocsec.shentsize)<>dynrelsize) then
InternalError(2012110601);
{ Write out non-RELATIVE dynamic relocations
TODO: additional sorting? }
for i:=0 to dynreloclist.count-1 do
begin
objreloc:=TObjRelocation(dynreloclist[i]);
WriteDynRelocEntry(objreloc.dataoffset,objreloc.ftype,objreloc.symbol.exesymbol.dynindex,0);
end;
end;
{ sanity checks }
if assigned(gotobjsec) and (gotsize<>gotobjsec.size) then
InternalError(2012092501);
if assigned(dynrelocsec) and (dynrelsize<>dynrelocsec.size) then
InternalError(2012092502);
if (ExeWriteMode=ewm_dbgonly) or
(
(ExeWriteMode=ewm_exefull) and
not(cs_link_strip in current_settings.globalswitches)
) then
WriteStaticSymtable;
{ first handle primary segments }
textseg.DataPos:=0;
CurrDataPos:=sizeof(TElfHeader)+sizeof(TElfproghdr)*segmentlist.count;
if assigned(phdrseg) then
begin
phdrseg.DataPos:=sizeof(TElfHeader);
phdrseg.DataSize:=sizeof(TElfproghdr)*segmentlist.count;
end;
DataPos_Segment(textseg);
CurrDataPos:=align(CurrDataPos,SectionDataAlign);
dataseg.DataPos:=CurrDataPos;
DataPos_Segment(dataseg);
{ then unmapped sections }
for i:=0 to ExeSectionList.Count-1 do
begin
exesec:=TExeSection(ExeSectionList[i]);
if not (oso_load in exesec.SecOptions) then
inherited DataPos_ExeSection(exesec);
end;
{ finally, update size/position of non-load segments }
for i:=0 to segmentlist.count-1 do
begin
seg:=TElfSegment(segmentlist[i]);
if (seg.ptype=PT_LOAD) or (seg.FSectionList.Count=0) then
continue;
seg.DataPos:=TExeSection(seg.FSectionList.First).DataPos;
for j:=0 to seg.FSectionList.Count-1 do
begin
exesec:=TExeSection(seg.FSectionList[j]);
if oso_data in exesec.SecOptions then
seg.DataSize:=exesec.DataPos+exesec.Size-seg.DataPos;
end;
end;
{ place section headers after the data }
shoffset:=CurrDataPos;
CurrDataPos:=CurrDataPos+ExeSectionList.Count*sizeof(TElfsechdr);
end;
procedure TElfExeOutput.DataPos_Segment(seg:TElfSegment);
var
i: longint;
exesec: TElfExeSection;
begin
for i:=0 to seg.FSectionList.Count-1 do
begin
exesec:=TElfExeSection(seg.FSectionList[i]);
{ ELF needs DataPos set to 'would-be' value for sections that
don't have data, and for non-debug sections in .dbg file, too.
This slightly differs from generic approach. }
if not (oso_data in exesec.SecOptions) or
(
(ExeWriteMode=ewm_dbgonly) and
(exesec.SecOptions*[oso_debug,oso_debug_copy]=[])
) then
begin
CurrDataPos:=align(CurrDataPos,SectionDataAlign);
exesec.DataPos:=CurrDataPos;
end
else
inherited DataPos_ExeSection(exesec);
end;
{ calculate size of the segment }
seg.DataSize:=CurrDataPos-seg.DataPos;
end;
procedure TElfExeOutput.DataPos_ExeSection(const aname:string);
begin
// Ignore. Work is done entirely in datapos_start.
end;
procedure TElfExeOutput.InitDynlink;
begin
if not IsSharedLibrary then
begin
interpobjsec:=internalObjData.createsection('.interp',1,[oso_data,oso_load,oso_keep]);
interpobjsec.writestr(interpreter^);
end;
hashobjsec:=TElfObjSection.create_ext(internalObjData,'.hash',
SHT_HASH,SHF_ALLOC,sizeof(pint),4);
hashobjsec.secoptions:=[oso_keep];
dynsymtable:=TElfSymtab.create(internalObjData,esk_dyn);
dynamicsec:=TElfObjSection.create_ext(internalObjData,'.dynamic',
SHT_DYNAMIC,SHF_ALLOC or SHF_WRITE,sizeof(pint),sizeof(TElfDyn));
dynamicsec.SecOptions:=[oso_keep];
dynrelocsec:=TElfObjSection.create_reloc(internalObjData,'.dyn',true);
dynrelocsec.SecOptions:=[oso_keep];
dynbssobjsec:=TElfObjSection.create_ext(internalObjData,'.dynbss',
SHT_NOBITS,SHF_ALLOC or SHF_WRITE,sizeof(pint){16??},0);
dynbssobjsec.SecOptions:=[oso_keep];
dynreloclist:=TFPObjectList.Create(true);
symversec:=TElfObjSection.create_ext(internalObjData,'.gnu.version',
SHT_GNU_VERSYM,SHF_ALLOC,sizeof(word),sizeof(word));
symversec.SecOptions:=[oso_keep];
verdefsec:=TElfObjSection.create_ext(internalObjData,'.gnu.version_d',
SHT_GNU_VERDEF,SHF_ALLOC,sizeof(pint),0);
verdefsec.SecOptions:=[oso_keep];
verneedsec:=TElfObjSection.create_ext(internalObjData,'.gnu.version_r',
SHT_GNU_VERNEED,SHF_ALLOC,sizeof(pint),0);
verneedsec.SecOptions:=[oso_keep];
dyncopysyms:=TFPObjectList.Create(False);
end;
const
hashbuckets: array[0..15] of longint=(
1, 3, 17, 37, 67, 97, 131, 197, 263, 521, 1031, 2053, 4099, 8209,
16411, 32771);
{$push}{$r-,q-}
function elfhash(const name:string):longword;
var
g: longword;
i: longint;
begin
result:=0;
for i:=1 to length(name) do
begin
result:=(result shl 4)+ord(name[i]);
g:=result and $F0000000;
if g>0 then
result:=result xor (g shr 24);
result:=result and (not g);
end;
end;
{$pop}
procedure TElfExeOutput.WriteDynamicSymbolsHash;
var
nchains,nbuckets: longint;
i,j: longint;
hashdata: plongint;
sym: TExeSymbol;
begin
dynsymnames:=AllocMem(dynsymlist.count*sizeof(longword));
nchains:=dynsymlist.Count+1;
{ determine suitable bucket count }
i:=high(hashbuckets);
while (i>=0) and (nchains<hashbuckets[i]) do
dec(i);
nbuckets:=hashbuckets[i];
hashdata:=AllocMem((2+nchains+nbuckets)*sizeof(longint));
hashdata[0]:=nbuckets;
hashdata[1]:=nchains;
{ The contents of .dynsym can be written only after mempos pass
because it needs valid symbol virtual addresses and section indices.
Here we preset .dynsym size and write names, in order to get
correct size of .dynstr section. }
dynsymtable.size:=(dynsymlist.count+1)*sizeof(TElfsymbol);
for i:=0 to dynsymlist.Count-1 do
begin
sym:=TExeSymbol(dynsymlist[i]);
dynsymnames[i]:=dynsymtable.fstrsec.writestr(sym.objsymbol.name);
j:=(elfhash(sym.objsymbol.name) mod nbuckets)+2;
while hashdata[j]<>0 do
j:=2+nbuckets+hashdata[j];
hashdata[j]:=i+1;
end;
if source_info.endian<>target_info.endian then
for i:=0 to nchains+nbuckets+1 do
hashdata[i]:=swapendian(hashdata[i]);
hashobjsec.write(hashdata^,(2+nchains+nbuckets)*sizeof(longint));
freemem(hashdata);
end;
procedure TElfExeOutput.WriteVersionSections;
var
i,j: longint;
idx,auxidx: longword;
exesym: TExeSymbol;
dynobj: TElfDynamicObjData;
ver: TElfVersionDef;
vn: TElfverneed;
vna: TElfvernaux;
symversions: pword;
begin
symversions:=AllocMem((dynsymlist.count+1)*sizeof(word));
{ Assign version indices }
idx:=VER_NDX_GLOBAL+1;
for i:=0 to dynsymlist.count-1 do
begin
exesym:=TExeSymbol(dynsymlist[i]);
if (exesym.objsymbol.indsymbol is TVersionedObjSymbol) then
ver:=TVersionedObjSymbol(exesym.objsymbol.indsymbol).version
else
ver:=nil;
if assigned(ver) then
begin
if ver.index=0 then
begin
ver.index:=idx;
inc(idx);
end;
symversions[i+1]:=ver.index;
end
else if exesym.state in [symstate_undefined,symstate_undefweak] then
symversions[i+1]:=VER_NDX_LOCAL
else
symversions[i+1]:=VER_NDX_GLOBAL;
end;
{ Count entries to be written }
verneedcount:=0;
for i:=0 to neededlist.count-1 do
begin
dynobj:=TElfDynamicObjData(neededlist[i]);
dynobj.vernaux_count:=0;
for j:=2 to dynobj.versiondefs.count-1 do
begin
ver:=TElfVersionDef(dynobj.versiondefs[j]);
if ver.index>VER_NDX_GLOBAL then
inc(dynobj.vernaux_count);
end;
if (dynobj.vernaux_count>0) then
inc(verneedcount);
end;
{ Now write }
idx:=0;
for i:=0 to neededlist.count-1 do
begin
dynobj:=TElfDynamicObjData(neededlist[i]);
if dynobj.vernaux_count=0 then
continue;
inc(idx);
vn.vn_version:=VER_NEED_CURRENT;
vn.vn_cnt:=dynobj.vernaux_count;
vn.vn_file:=dynobj.soname_strofs;
vn.vn_aux:=sizeof(TElfverneed);
vn.vn_next:=ord(idx<verneedcount)*(sizeof(TElfverneed)+vn.vn_cnt*sizeof(TElfvernaux));
MaybeSwapElfverneed(vn);
verneedsec.write(vn,sizeof(TElfverneed));
auxidx:=0;
for j:=2 to dynobj.versiondefs.count-1 do
begin
ver:=TElfVersionDef(dynobj.versiondefs[j]);
if ver.index<=VER_NDX_GLOBAL then
continue;
inc(auxidx);
vna.vna_hash:=elfhash(ver.name);
vna.vna_flags:=0; { BFD copies this from verdef.vd_flags?? }
vna.vna_other:=ver.index;
vna.vna_name:=dynsymtable.fstrsec.writestr(ver.name);
vna.vna_next:=ord(auxidx<dynobj.vernaux_count)*sizeof(TElfvernaux);
MaybeSwapElfvernaux(vna);
verneedsec.write(vna,sizeof(TElfvernaux));
end;
end;
TElfExeSection(verneedsec.ExeSection).shinfo:=verneedcount;
{ If there are no needed versions, .gnu.version section is not needed }
if verneedcount>0 then
begin
if source_info.endian<>target_info.endian then
for i:=0 to dynsymlist.count+1 do
symversions[i]:=swapendian(symversions[i]);
symversec.write(symversions^,(dynsymlist.count+1)*sizeof(word));
end;
FreeMem(symversions);
end;
procedure TElfExeOutput.WriteDynRelocEntry(dataofs:aword;typ:byte;symidx:aword;addend:aword);
var
rel:telfreloc;
begin
rel.address:=dataofs;
rel.info:=ELF_R_INFO(symidx,typ);
{$push}{$r-}
rel.addend:=addend;
{$pop}
MaybeSwapElfReloc(rel);
dynrelocsec.write(rel,dynrelocsec.shentsize);
end;
procedure TElfExeOutput.WriteDynTag(aTag:longword;aValue:longword);
var
d: TElfDyn;
begin
d.d_tag:=aTag;
d.d_val:=aValue;
MaybeSwapElfDyn(d);
dynamicsec.write(d,sizeof(TElfDyn));
end;
procedure TElfExeOutput.WriteDynTag(aTag:longword;aSection:TObjSection;aOffs:aword);
var
d: TElfDyn;
begin
d.d_tag:=aTag;
if source_info.endian<>target_info.endian then
d.d_tag:=swapendian(d.d_tag);
dynamicsec.write(d.d_tag,sizeof(d.d_tag));
{ TODO: ignores endianness! }
dynamicsec.writeReloc_internal(aSection,aOffs,sizeof(d.d_ptr),RELOC_ABSOLUTE);
end;
procedure TElfExeOutput.WriteTargetDynamicTags;
begin
{ to be overridden by CPU-specific descendants }
end;
procedure TElfExeOutput.WriteDynamicTags;
var
s: aword;
i: longint;
sym: TExeSymbol;
hs:string;
dynobj: TElfDynamicObjData;
begin
for i:=0 to neededlist.Count-1 do
begin
dynobj:=TElfDynamicObjData(neededlist[i]);
s:=dynsymtable.fstrsec.writestr(dynobj.name);
dynobj.soname_strofs:=s;
WriteDynTag(DT_NEEDED,s);
end;
if IsSharedLibrary then
begin
s:=dynsymtable.fstrsec.writestr(ExtractFileName(current_module.sharedlibfilename));
WriteDynTag(DT_SONAME,s);
{ TODO: names hardcoded here }
sym:=TExeSymbol(ExeSymbolList.Find('FPC_SHARED_LIB_START'));
if assigned(sym) then
WriteDynTag(DT_INIT,sym.objsymbol.objsection,sym.objsymbol.offset);
sym:=TExeSymbol(ExeSymbolList.Find('FPC_LIB_EXIT'));
if assigned(sym) then
WriteDynTag(DT_FINI,sym.objsymbol.objsection,sym.objsymbol.offset);
end;
{ TODO: we need a dedicated parameter to pass runpath, instead of this hack
(-Xr is a different thing, it passes "-rpath-link"). }
if (ParaLinkOptions<>'') then
begin
hs:=ParaLinkOptions;
while (hs<>'') do
begin
if (GetToken(hs,' ')='-rpath') then
begin
s:=dynsymtable.fstrsec.writestr(GetToken(hs,' '));
WriteDynTag(DT_RPATH,s);
end;
end;
end;
if assigned(preinitarraysec) then
begin
WriteDynTag(DT_PREINIT_ARRAY,preinitarraysec,0);
WriteDynTag(DT_PREINIT_ARRAYSZ,preinitarraysec.exesection.size);
end;
if assigned(initarraysec) then
begin
WriteDynTag(DT_INIT_ARRAY,initarraysec,0);
WriteDynTag(DT_INIT_ARRAYSZ,initarraysec.exesection.size);
end;
if assigned(finiarraysec) then
begin
WriteDynTag(DT_FINI_ARRAY,finiarraysec,0);
WriteDynTag(DT_FINI_ARRAYSZ,finiarraysec.exesection.size);
end;
writeDynTag(DT_HASH,hashobjsec);
writeDynTag(DT_STRTAB,dynsymtable.fstrsec);
writeDynTag(DT_SYMTAB,dynsymtable);
writeDynTag(DT_SYMENT,sizeof(TElfSymbol));
if Assigned(gotpltobjsec) then
writeDynTag(DT_PLTGOT,gotpltobjsec);
end;
const
pltreltags: array[boolean] of longword=(DT_REL,DT_RELA);
relsztags: array[boolean] of longword=(DT_RELSZ,DT_RELASZ);
relenttags: array[boolean] of longword=(DT_RELENT,DT_RELAENT);
{$ifndef MIPS}
relcnttags: array[boolean] of longword=(DT_RELCOUNT,DT_RELACOUNT);
{$endif MIPS}
procedure TElfExeOutput.FinishDynamicTags;
var
rela: boolean;
begin
if assigned(dynsymtable) then
writeDynTag(DT_STRSZ,dynsymtable.fstrsec.size);
if hastextrelocs then
writeDynTag(DT_TEXTREL,0);
if Assigned(pltrelocsec) and (pltrelocsec.size>0) then
begin
writeDynTag(DT_PLTRELSZ,pltrelocsec.Size);
writeDynTag(DT_PLTREL,pltreltags[pltrelocsec.shtype=SHT_RELA]);
writeDynTag(DT_JMPREL,pltrelocsec);
end;
if Assigned(dynrelocsec) and (dynrelocsec.size>0) then
begin
rela:=(dynrelocsec.shtype=SHT_RELA);
writeDynTag(pltreltags[rela],dynrelocsec);
writeDynTag(relsztags[rela],dynrelocsec.Size);
writeDynTag(relenttags[rela],dynrelocsec.shentsize);
{$ifndef MIPS}
if (relative_reloc_count>0) then
writeDynTag(relcnttags[rela],relative_reloc_count);
{$endif MIPS}
end;
WriteTargetDynamicTags;
if (verdefcount>0) or (verneedcount>0) then
begin
if (verdefcount>0) then
begin
writeDynTag(DT_VERDEF,verdefsec);
writeDynTag(DT_VERDEFNUM,verdefcount);
end;
if (verneedcount>0) then
begin
writeDynTag(DT_VERNEED,verneedsec);
writeDynTag(DT_VERNEEDNUM,verneedcount);
end;
writeDynTag(DT_VERSYM,symversec);
end;
writeDynTag(DT_NULL,0);
end;
procedure TElfExeOutput.CreatePLT;
var
reloc: TObjRelocation;
begin
pltobjsec:=TElfObjSection.create_ext(internalObjData,'.plt',
SHT_PROGBITS,SHF_ALLOC or SHF_EXECINSTR,4,16);
pltobjsec.SecOptions:=[oso_keep,oso_plt];
pltrelocsec:=TElfObjSection.create_reloc(internalObjData,'.plt',true);
pltrelocsec.SecOptions:=[oso_keep];
ipltrelocsec:=TElfObjSection.create_reloc(internalObjData,'.iplt',true);
ipltrelocsec.SecOptions:=[oso_keep];
{ reference .dynamic from .got.plt, this isn't necessary if linking statically }
{ TODO: maybe move writing initial .got.plt entries here completely
(needs testing --- GOT symbol may get lost if .got.plt is empty)}
if dynamiclink then
begin
reloc:=TObjRelocation.CreateSection(0,dynamicsec,RELOC_ABSOLUTE);
reloc.size:=sizeof(pint);
gotpltobjsec.ObjRelocations.Add(reloc);
end;
{ Initial PLT entry, CPU-specific }
WriteFirstPLTEntry;
end;
procedure TElfExeOutput.WritePLTEntry(exesym:TExeSymbol);
begin
// must be implemented by CPU-specific descendant
InternalError(2012092102);
end;
procedure TElfExeOutput.WriteIndirectPLTEntry(exesym:TExeSymbol);
begin
// must be implemented by CPU-specific descendant
InternalError(2012092101);
end;
function TElfExeOutput.WriteData:boolean;
begin
WriteHeader;
segmentlist.ForEachCall(@segment_write_header,nil);
WriteExeSectionContent;
FWriter.WriteZeros(sizeof(TElfsechdr));
ExeSectionList.ForEachCall(@exesection_write_header,nil);
result:=true;
end;
procedure TElfExeOutput.GenerateLibraryImports(ImportLibraryList:TFPHashObjectList);
var
exportlist: TCmdStrList;
sym: TExeSymbol;
begin
AllowUndefinedSymbols:=IsSharedLibrary;
{ add exported symbols to dynamic list }
exportlist:=texportlibunix(exportlib).exportedsymnames;
if not exportlist.empty then
repeat
sym:=TExeSymbol(ExeSymbolList.Find(exportlist.getfirst));
if assigned(sym) then
begin
if assigned(sym.objsymbol.objsection) then
sym.objsymbol.objsection.SecOptions:=[oso_keep];
sym.dynindex:=dynsymlist.add(sym)+1
end
else
InternalError(2012071801);
until exportlist.empty;
end;
procedure TElfExeOutput.ReportNonDSOReloc(reltyp:byte;objsec:TObjSection;ObjReloc:TObjRelocation);
begin
{ TODO: include objsec properties into message }
Comment(v_error,'Relocation '+ElfTarget.RelocName(reltyp)+' against '''+objreloc.TargetName+''' cannot be used when linking a shared object; recompile with -Cg');
end;
procedure TElfExeOutput.ReportRelocOverflow(reltyp:byte;objsec:TObjSection;ObjReloc:TObjRelocation);
begin
{ TODO: include objsec properties into message }
Comment(v_error,'Relocation truncated to fit: '+ElfTarget.RelocName(reltyp)+' against '''+objreloc.TargetName+'''');
end;
{****************************************************************************
TElfExeSection
****************************************************************************}
procedure TElfExeSection.AddObjSection(objsec:TObjSection;ignoreprops:boolean);
begin
inherited AddObjSection(objsec,ignoreprops);
if ignoreprops then
exit;
if (shtype=SHT_NULL) then
begin
shtype:=TElfObjSection(objsec).shtype;
shflags:=TElfObjSection(objsec).shflags;
shentsize:=TElfObjSection(objsec).shentsize;
end;
end;
{****************************************************************************
TElfSegment
****************************************************************************}
constructor TElfSegment.Create(atype,aflags,aalign:longword);
begin
ptype:=atype;
pflags:=aflags;
align:=aalign;
FSectionList:=TFPObjectList.Create(false);
end;
destructor TElfSegment.Destroy;
begin
FSectionList.Free;
inherited Destroy;
end;
procedure TElfSegment.Add(exesec:TExeSection);
begin
FSectionList.Add(exesec);
end;
end.