{ $Id$ Copyright (c) 1998-2000 by Peter Vreman Contains the binary elf writer * This code was inspired by the NASM sources The Netwide Assembler is copyright (C) 1996 Simon Tatham and Julian Hall. All rights reserved. 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; {$i defines.inc} interface uses { common } cclasses,cobjects, { target } systems, { assembler } cpubase,aasm, { output } ogbase; type telf32section = class(tobjectsection) public secshidx : longint; { index for the section in symtab } shstridx, shtype, shflags, shlink, shinfo, entsize : longint; { relocation } relocsect : telf32Section; constructor createsec(sec:TSection); constructor createname(const Aname:string;Atype,Aflags,Alink,Ainfo,Aalign,Aentsize:longint); destructor destroy;override; end; telf32data = class(tobjectdata) public symtabsect, strtabsect, shstrtabsect, gotpcsect, gotoffsect, gotsect, pltsect, symsect : telf32Section; syms : Tdynamicarray; constructor create; destructor destroy;override; procedure createsection(sec:tsection);override; procedure setsectionsizes(var s:tsecsize);override; procedure writereloc(data,len:longint;p:pasmsymbol;relative:relative_type);override; procedure writesymbol(p:pasmsymbol);override; procedure writestabs(section:tsection;offset:longint;p:pchar;nidx,nother,line:longint;reloc:boolean);override; procedure writesymstabs(section:tsection;offset:longint;p:pchar;ps:pasmsymbol; nidx,nother,line:longint;reloc:boolean);override; end; telf32output = class(tobjectoutput) private initsym : longint; procedure createrelocsection(s:telf32section); procedure createshstrtab; procedure createsymtab; procedure writesectionheader(s:telf32section); protected procedure writetodisk;override; public function initwriting(Aplace:tcutplace):tobjectdata;override; end; implementation uses {$ifdef delphi} sysutils, {$else} strings, {$endif} verbose, globtype,cutils,globals,fmodule; const symbolresize = 200*18; DataResize = 8192; const R_386_32 = 1; { ordinary absolute relocation } R_386_PC32 = 2; { PC-relative relocation } R_386_GOT32 = 3; { an offset into GOT } R_386_PLT32 = 4; { a PC-relative offset into PLT } R_386_GOTOFF = 9; { an offset from GOT base } R_386_GOTPC = 10; { a PC-relative offset _to_ GOT } SHN_UNDEF = 0; SHN_ABS = $fff1; SHN_COMMON = $fff2; SHT_NULL = 0; SHT_PROGBITS = 1; SHT_SYMTAB = 2; SHT_STRTAB = 3; SHT_RELA = 4; SHT_HASH = 5; SHT_DYNAMIC = 6; SHT_NOTE = 7; SHT_NOBITS = 8; SHT_REL = 9; SHT_SHLIB = 10; SHT_DYNSYM = 11; SHF_WRITE = 1; SHF_ALLOC = 2; SHF_EXECINSTR = 4; STB_LOCAL = 0; STB_GLOBAL = 1; STB_WEAK = 2; STT_NOTYPE = 0; STT_OBJECT = 1; STT_FUNC = 2; STT_SECTION = 3; STT_FILE = 4; type { Structures which are written directly to the output file } telf32header=packed record magic0123 : longint; file_class : byte; data_encoding : byte; file_version : byte; padding : array[$07..$0f] of byte; e_type : word; e_machine : word; e_version : longint; e_entry : longint; { entrypoint } e_phoff : longint; { program header offset } e_shoff : longint; { sections header offset } e_flags : longint; e_ehsize : word; { elf header size in bytes } e_phentsize : word; { size of an entry in the program header array } e_phnum : word; { 0..e_phnum-1 of entrys } e_shentsize : word; { size of an entry in sections header array } e_shnum : word; { 0..e_shnum-1 of entrys } e_shstrndx : word; { index of string section header } end; telf32sechdr=packed record sh_name : longint; sh_type : longint; sh_flags : longint; sh_addr : longint; sh_offset : longint; sh_size : longint; sh_link : longint; sh_info : longint; sh_addralign : longint; sh_entsize : longint; end; pelf32reloc=^telf32reloc; telf32reloc=packed record address : longint; info : longint; { bit 0-7: type, 8-31: symbol } end; pelf32symbol=^telf32symbol; telf32symbol=packed record st_name : longint; st_value : longint; st_size : longint; st_info : byte; { bit 0-3: type, 4-7: bind } st_other : byte; st_shndx : word; end; pelf32stab=^telf32stab; telf32stab=packed record strpos : longint; ntype : byte; nother : byte; ndesc : word; nvalue : longint; end; {**************************************************************************** TSection ****************************************************************************} constructor telf32section.createsec(sec:TSection); var Aflags,Atype,Aalign,Aentsize : longint; begin Aflags:=0; Atype:=0; Aalign:=0; Aentsize:=0; case sec of sec_code : begin Aflags:=SHF_ALLOC or SHF_EXECINSTR; AType:=SHT_PROGBITS; AAlign:=16; end; sec_data : begin Aflags:=SHF_ALLOC or SHF_WRITE; AType:=SHT_PROGBITS; AAlign:=4; end; sec_bss : begin Aflags:=SHF_ALLOC or SHF_WRITE; AType:=SHT_NOBITS; AAlign:=4; end; sec_stab : begin AType:=SHT_PROGBITS; AAlign:=4; Aentsize:=sizeof(telf32stab); end; sec_stabstr : begin AType:=SHT_STRTAB; AAlign:=1; end; end; createname(target_asm.secnames[sec],Atype,Aflags,0,0,Aalign,Aentsize); end; constructor telf32section.createname(const Aname:string;Atype,Aflags,Alink,Ainfo,Aalign,Aentsize:longint); begin inherited create(Aname,Aalign,(AType=SHT_NOBITS)); secshidx:=0; shstridx:=0; shtype:=AType; shflags:=AFlags; shlink:=Alink; shinfo:=Ainfo; entsize:=Aentsize; relocsect:=nil; end; destructor telf32section.destroy; begin if assigned(relocsect) then relocsect.free; inherited destroy; end; {**************************************************************************** TElf32Data ****************************************************************************} constructor telf32data.create; var s : string; begin inherited create; { reset } Syms:=TDynamicArray.Create(symbolresize); { default sections } symtabsect:=telf32section.createname('.symtab',2,0,0,0,4,16); strtabsect:=telf32section.createname('.strtab',3,0,0,0,1,0); shstrtabsect:=telf32section.createname('.shstrtab',3,0,0,0,1,0); { insert the empty and filename as first in strtab } strtabsect.writestr(#0); strtabsect.writestr(SplitFileName(current_module.mainsource^)+#0); { we need at least the following sections } createsection(sec_code); createsection(sec_data); createsection(sec_bss); { create stabs sections if debugging } if (cs_debuginfo in aktmoduleswitches) then begin createsection(sec_stab); createsection(sec_stabstr); writestabs(sec_none,0,nil,0,0,0,false); { write zero pchar and name together (PM) } s:=#0+SplitFileName(current_module.mainsource^)+#0; sects[sec_stabstr].write(s[1],length(s)); end; end; destructor telf32data.destroy; begin Syms.Free; symtabsect.free; strtabsect.free; shstrtabsect.free; inherited destroy; end; procedure telf32data.createsection(sec:tsection); begin sects[sec]:=telf32Section.createsec(Sec); end; procedure telf32data.writesymbol(p:pasmsymbol); var sym : toutputsymbol; begin { already written ? } if p^.idx<>-1 then exit; { be sure that the section will exists } if (p^.section<>sec_none) and not(assigned(sects[p^.section])) then createsection(p^.section); FillChar(sym,sizeof(sym),0); sym.size:=p^.size; sym.bind:=p^.bind; sym.typ:=p^.typ; { if local of global then set the section value to the address of the symbol } case sym.bind of AB_LOCAL, AB_GLOBAL : begin sym.section:=p^.section; sym.value:=p^.address; end; AB_COMMON : begin sym.value:=$10; end; end; { store the symbol, but not the local ones } if (sym.bind<>AB_LOCAL) then begin { symbolname, write the #0 separate to overcome 255+1 char not possible } sym.nameidx:=strtabsect.datasize; strtabsect.writestr(p^.name); strtabsect.writestr(#0); { update the asmsymbol index } p^.idx:=syms.size div sizeof(toutputsymbol); { symbol } Syms.write(sym,sizeof(toutputsymbol)); end else begin p^.idx:=-2; { local } end; end; procedure telf32data.writereloc(data,len:longint;p:pasmsymbol;relative:relative_type); var symaddr : longint; begin if not assigned(sects[currsec]) then createsection(currsec); if assigned(p) then begin { real address of the symbol } symaddr:=p^.address; { no symbol relocation need inside a section } if p^.section=currsec then begin case relative of relative_false : begin sects[currsec].addsectionreloc(sects[currsec].datasize,currsec,relative_false); inc(data,symaddr); end; relative_true : begin inc(data,symaddr-len-sects[currsec].datasize); end; relative_rva : internalerror(3219583); end; end else begin writesymbol(p); if (p^.section<>sec_none) and (relative<>relative_true) then begin sects[currsec].addsectionreloc(sects[currsec].datasize,p^.section,relative); inc(data,symaddr); end else sects[currsec].addsymreloc(sects[currsec].datasize,p,relative); if relative=relative_true then begin if p^.bind=AB_EXTERNAL then dec(data,len) else dec(data,len+sects[currsec].datasize); end; end; end; sects[currsec].write(data,len); end; procedure telf32data.writestabs(section:tsection;offset:longint;p:pchar;nidx,nother,line:longint;reloc : boolean); var stab : telf32stab; s : tsection; begin s:=section; if reloc then begin if (offset=-1) then begin if s=sec_none then offset:=0 else offset:=sects[s].datasize; end; end; fillchar(stab,sizeof(telf32stab),0); if assigned(p) and (p[0]<>#0) then begin stab.strpos:=sects[sec_stabstr].datasize; sects[sec_stabstr].write(p^,strlen(p)+1); end; stab.ntype:=nidx; stab.ndesc:=line; stab.nother:=nother; stab.nvalue:=offset; sects[sec_stab].write(stab,sizeof(stab)); { when the offset is not 0 then write a relocation, take also the hdrstab into account with the offset } if reloc then sects[sec_stab].addsectionreloc(sects[sec_stab].datasize-4,s,relative_false); end; procedure telf32data.writesymstabs(section:tsection;offset:longint;p:pchar;ps:pasmsymbol; nidx,nother,line:longint;reloc:boolean); var stab : telf32stab; begin if reloc then begin if (offset=-1) then begin if section=sec_none then offset:=0 else offset:=sects[section].datasize; end; end; fillchar(stab,sizeof(telf32stab),0); if assigned(p) and (p[0]<>#0) then begin stab.strpos:=sects[sec_stabstr].datasize; sects[sec_stabstr].write(p^,strlen(p)+1); end; stab.ntype:=nidx; stab.ndesc:=line; stab.nother:=nother; stab.nvalue:=offset; sects[sec_stab].write(stab,sizeof(stab)); { when the offset is not 0 then write a relocation, take also the hdrstab into account with the offset } if reloc then sects[sec_stab].addsymreloc(sects[sec_stab].datasize-4,ps,relative_false); end; procedure telf32data.setsectionsizes(var s:tsecsize); begin end; {**************************************************************************** TElf32Output ****************************************************************************} function telf32output.initwriting(Aplace:tcutplace):tobjectdata; begin inherited initwriting(Aplace); initsym:=0; data:=telf32data.create; initwriting:=data; end; procedure telf32output.createrelocsection(s:telf32section); var rel : telf32reloc; hr,r : poutputreloc; relsym,reltyp : longint; begin with telf32data(data) do begin { create the reloc section } s.relocsect:=telf32section.createname('.rel'+s.name,9,0,symtabsect.secshidx,s.secshidx,4,8); { add the relocations } r:=s.relochead; while assigned(r) do begin rel.address:=r^.address; if assigned(r^.symbol) then begin if (r^.symbol^.bind=AB_LOCAL) then relsym:=sects[r^.symbol^.section].secsymidx else begin if r^.symbol^.idx=-1 then internalerror(4321); relsym:=(r^.symbol^.idx+initsym); end; end else if r^.section<>sec_none then relsym:=sects[r^.section].secsymidx else relsym:=SHN_UNDEF; case r^.typ of relative_true : reltyp:=R_386_PC32; relative_false : reltyp:=R_386_32; end; rel.info:=(relsym shl 8) or reltyp; { write reloc } s.relocsect.write(rel,sizeof(rel)); { goto next and dispose this reloc } hr:=r; r:=r^.next; dispose(hr); end; end; end; procedure telf32output.createsymtab; var elfsym : telf32symbol; sym : toutputsymbol; sec : tsection; locals, i : longint; begin with telf32data(data) do begin locals:=2; { empty entry } fillchar(elfsym,sizeof(elfsym),0); symtabsect.write(elfsym,sizeof(elfsym)); { filename entry } elfsym.st_name:=1; elfsym.st_info:=STT_FILE; elfsym.st_shndx:=SHN_ABS; symtabsect.write(elfsym,sizeof(elfsym)); { section } for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) then begin fillchar(elfsym,sizeof(elfsym),0); elfsym.st_name:=telf32section(sects[sec]).shstridx; elfsym.st_info:=STT_SECTION; elfsym.st_shndx:=telf32section(sects[sec]).secshidx; symtabsect.write(elfsym,sizeof(elfsym)); inc(locals); end; { symbols } Syms.seek(0); for i:=1 to (Syms.size div sizeof(toutputsymbol)) do begin Syms.read(sym,sizeof(toutputsymbol)); fillchar(elfsym,sizeof(elfsym),0); elfsym.st_name:=sym.nameidx; elfsym.st_value:=sym.value; elfsym.st_size:=sym.size; case sym.bind of AB_LOCAL : begin elfsym.st_info:=STB_LOCAL shl 4; inc(locals); end; AB_COMMON, AB_EXTERNAL, AB_GLOBAL : elfsym.st_info:=STB_GLOBAL shl 4; end; if sym.bind<>AB_EXTERNAL then begin case sym.typ of AT_FUNCTION : elfsym.st_info:=elfsym.st_info or STT_FUNC; AT_DATA : elfsym.st_info:=elfsym.st_info or STT_OBJECT; end; end; if sym.bind=AB_COMMON then elfsym.st_shndx:=SHN_COMMON else if assigned(sects[sym.section]) then elfsym.st_shndx:=telf32section(sects[sym.section]).secshidx else elfsym.st_shndx:=SHN_UNDEF; symtabsect.write(elfsym,sizeof(elfsym)); end; { update the .symtab section header } symtabsect.shlink:=strtabsect.secshidx; symtabsect.shinfo:=locals; end; end; procedure telf32output.createshstrtab; var sec : tsection; begin with telf32data(data) do begin with shstrtabsect do begin writestr(#0); symtabsect.shstridx:=writestr('.symtab'#0); strtabsect.shstridx:=writestr('.strtab'#0); shstrtabsect.shstridx:=writestr('.shstrtab'#0); for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) then begin telf32section(sects[sec]).shstridx:=writestr(sects[sec].name+#0); if assigned(telf32section(sects[sec]).relocsect) then telf32section(sects[sec]).relocsect.shstridx:=writestr(telf32section(sects[sec]).relocsect.name+#0); end; end; end; end; procedure telf32output.writesectionheader(s:telf32section); var sechdr : telf32sechdr; 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.datasize; sechdr.sh_link:=s.shlink; sechdr.sh_info:=s.shinfo; sechdr.sh_addralign:=s.addralign; sechdr.sh_entsize:=s.entsize; writer.write(sechdr,sizeof(sechdr)); end; procedure telf32output.writetodisk; var header : telf32header; datapos, shoffset, nsects : longint; hstab : telf32stab; sec : tsection; empty : array[0..63] of byte; hp : pdynamicblock; begin with telf32data(data) do begin { calc amount of sections we have } fillchar(empty,sizeof(empty),0); nsects:=1; initsym:=2; for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) then begin { each section requires a symbol for relocation } sects[sec].secsymidx:=initsym; inc(initsym); { also create the index in the section header table } telf32section(sects[sec]).secshidx:=nsects; inc(nsects); if assigned(sects[sec].relochead) then inc(nsects); end; { add default sections follows } shstrtabsect.secshidx:=nsects; inc(nsects); symtabsect.secshidx:=nsects; inc(nsects); strtabsect.secshidx:=nsects; inc(nsects); { For the stab section we need an HdrSym which can now be calculated more easily } if assigned(sects[sec_stab]) then begin hstab.strpos:=1; hstab.ntype:=0; hstab.nother:=0; hstab.ndesc:=(sects[sec_stab].datasize div sizeof(telf32stab))-1{+1 according to gas output PM}; hstab.nvalue:=sects[sec_stabstr].datasize; sects[sec_stab].Data.seek(0); sects[sec_stab].Data.write(hstab,sizeof(hstab)); end; { Create the relocation sections } for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) and (sects[sec].nrelocs>0) then createrelocsection(telf32section(sects[sec])); { create .symtab } createsymtab; { create .shstrtab } createshstrtab; { Calculate the filepositions } datapos:=$40; { elfheader + alignment } { sections first } for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) then begin sects[sec].datapos:=datapos; if assigned(sects[sec].data) then inc(datapos,sects[sec].aligneddatasize); end; { shstrtab } shstrtabsect.datapos:=datapos; inc(datapos,shstrtabsect.aligneddatasize); { section headers } shoffset:=datapos; inc(datapos,nsects*sizeof(telf32sechdr)); { symtab } symtabsect.datapos:=datapos; inc(datapos,symtabsect.aligneddatasize); { strtab } strtabsect.datapos:=datapos; inc(datapos,align(strtabsect.datasize,4)); { .rel sections } for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) and assigned(telf32section(sects[sec]).relocsect) then begin telf32section(sects[sec]).relocsect.datapos:=datapos; inc(datapos,telf32section(sects[sec]).relocsect.aligneddatasize); end; { Write ELF Header } fillchar(header,sizeof(header),0); header.magic0123:=$464c457f; { = #127'ELF' } header.file_class:=1; header.data_encoding:=1; header.file_version:=1; header.e_type:=1; header.e_machine:=3; header.e_version:=1; header.e_shoff:=shoffset; header.e_shstrndx:=shstrtabsect.secshidx; header.e_shnum:=nsects; header.e_ehsize:=sizeof(telf32header); header.e_shentsize:=sizeof(telf32sechdr); writer.write(header,sizeof(header)); writer.write(empty,$40-sizeof(header)); { align } { Sections } for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) and assigned(sects[sec].data) then begin sects[sec].alignsection; hp:=sects[sec].Data.firstblock; while assigned(hp) do begin writer.write(hp^.data,hp^.used); hp:=hp^.next; end; end; { .shstrtab } shstrtabsect.alignsection; hp:=shstrtabsect.Data.firstblock; while assigned(hp) do begin writer.write(hp^.data,hp^.used); hp:=hp^.next; end; { section headers, start with an empty header for sh_undef } writer.write(empty,sizeof(telf32sechdr)); for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) then begin writesectionheader(telf32section(sects[sec])); if assigned(telf32section(sects[sec]).relocsect) then writesectionheader(telf32section(sects[sec]).relocsect); end; writesectionheader(shstrtabsect); writesectionheader(symtabsect); writesectionheader(strtabsect); { .symtab } symtabsect.alignsection; hp:=symtabsect.Data.firstblock; while assigned(hp) do begin writer.write(hp^.data,hp^.used); hp:=hp^.next; end; { .strtab } strtabsect.writealign(4); hp:=strtabsect.Data.firstblock; while assigned(hp) do begin writer.write(hp^.data,hp^.used); hp:=hp^.next; end; { .rel sections } for sec:=low(tsection) to high(tsection) do if assigned(sects[sec]) and assigned(telf32section(sects[sec]).relocsect) then begin telf32section(sects[sec]).relocsect.alignsection; hp:=telf32section(sects[sec]).relocsect.Data.firstblock; while assigned(hp) do begin writer.write(hp^.data,hp^.used); hp:=hp^.next; end; end; end; end; end. { $Log$ Revision 1.5 2000-12-25 00:07:26 peter + new tlinkedlist class (merge of old tstringqueue,tcontainer and tlinkedlist objects) Revision 1.4 2000/12/24 12:25:32 peter + cstreams unit * dynamicarray object to class Revision 1.3 2000/12/23 19:59:35 peter * object to class for ow/og objects * split objectdata from objectoutput Revision 1.2 2000/11/12 22:45:14 peter * moved setting of stab hdrsym Revision 1.1 2000/11/12 22:20:37 peter * create generic toutputsection for binary writers }