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fpc/compiler/mips/cpuelf.pas
sergei 578348817b * MIPS: some progress with linker: 
* Fixed values of R_MIPS_GOT_HI16/LO16.
  + Implemented elf_mips_relocname
  + Check R_MIPS_PC16 relocations for overflows
  + Handle R_MIPS_JALR optimization hint.

git-svn-id: trunk@33240 -
2016-03-13 17:13:23 +00:00

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{
Copyright (c) 2012 by Sergei Gorelkin
Includes ELF-related code specific to MIPS
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 cpuelf;
interface
{$i fpcdefs.inc}
implementation
uses
globtype,sysutils,cutils,cclasses,
verbose, elfbase,
systems,aasmbase,ogbase,ogelf,assemble;
type
TElfExeOutputMIPS=class(TElfExeOutput)
private
gpdispsym: TObjSymbol;
gnugpsym: TObjSymbol;
dt_gotsym_value: longint;
dt_local_gotno_value: longint;
dt_local_gotno_offset: aword;
local_got_relocs: TFPObjectList;
local_got_slots: TFPHashObjectList;
got_content: array of pint;
pic_stub_syms: TFPObjectList;
pic_stubs: THashSet;
nullstub: TObjSymbol;
stubcount: longint;
trampolinesection: TObjSection;
procedure MaybeWriteGOTEntry(relocval:aint;objsym:TObjSymbol);
procedure MaybeWriteTLSIEGotEntry(relocval:aint;objsym:TObjSymbol);
procedure CreatePICStub(objsym:TObjSymbol);
protected
procedure PrepareGOT;override;
function AllocGOTSlot(objsym:TObjSymbol):boolean;override;
procedure CreateGOTSection;override;
procedure CreatePLT;override;
procedure WriteTargetDynamicTags;override;
// procedure WriteFirstPLTEntry;override;
procedure WritePLTEntry(exesym:TExeSymbol);override;
// procedure WriteIndirectPLTEntry(exesym:TExeSymbol);override;
procedure GOTRelocPass1(objsec:TObjSection;var idx:longint);override;
procedure DoRelocationFixup(objsec:TObjSection);override;
procedure Do_Mempos;override;
public
constructor Create;override;
destructor Destroy;override;
procedure FixupRelocations;override;
end;
const
{ ELF header e_flags }
EF_MIPS_NOREORDER = 1;
EF_MIPS_PIC = 2;
EF_MIPS_CPIC = 4;
EF_MIPS_ABI = $0000F000;
E_MIPS_ABI_O32 = $00001000;
E_MIPS_ABI_O64 = $00002000;
E_MIPS_ABI_EABI32 = $00003000;
E_MIPS_ABI_EABI64 = $00004000;
EF_MIPS_ARCH = $F0000000;
E_MIPS_ARCH_1 = $00000000; // -mips1
E_MIPS_ARCH_2 = $10000000;
E_MIPS_ARCH_3 = $20000000;
E_MIPS_ARCH_4 = $30000000;
E_MIPS_ARCH_5 = $40000000;
E_MIPS_ARCH_32 = $50000000; // -mips32
E_MIPS_ARCH_64 = $60000000;
E_MIPS_ARCH_32R2= $70000000; // -mips32r2
E_MIPS_ARCH_64R2= $80000000;
{ section types }
SHT_MIPS_LIBLIST = $70000000;
SHT_MIPS_CONFLICT = $70000002;
SHT_MIPS_GPTAB = $70000003;
SHT_MIPS_UCODE = $70000004;
SHT_MIPS_DEBUG = $70000005;
SHT_MIPS_REGINFO = $70000006;
SHT_MIPS_DWARF = $7000001e;
{ section flags }
SHF_MIPS_GPREL = $10000000;
{ relocations }
R_MIPS_NONE = 0;
R_MIPS_16 = 1;
R_MIPS_32 = 2;
R_MIPS_REL32 = 3;
R_MIPS_26 = 4;
R_MIPS_HI16 = 5;
R_MIPS_LO16 = 6;
R_MIPS_GPREL16 = 7;
R_MIPS_LITERAL = 8;
R_MIPS_GOT16 = 9;
R_MIPS_PC16 = 10;
R_MIPS_CALL16 = 11;
R_MIPS_GPREL32 = 12;
R_MIPS_GOT_HI16 = 22;
R_MIPS_GOT_LO16 = 23;
R_MIPS_CALL_HI16 = 30;
R_MIPS_CALL_LO16 = 31;
R_MIPS_JALR = 37;
R_MIPS_TLS_DTPMOD32 = 38;
R_MIPS_TLS_DTPREL32 = 39;
R_MIPS_TLS_DTPMOD64 = 40;
R_MIPS_TLS_DTPREL64 = 41;
R_MIPS_TLS_GD = 42;
R_MIPS_TLS_LDM = 43;
R_MIPS_TLS_DTPREL_HI16 = 44;
R_MIPS_TLS_DTPREL_LO16 = 45;
R_MIPS_TLS_GOTTPREL = 46;
R_MIPS_TLS_TPREL32 = 47;
R_MIPS_TLS_TPREL64 = 48;
R_MIPS_TLS_TPREL_HI16 = 49;
R_MIPS_TLS_TPREL_LO16 = 50;
{ dynamic tags }
DT_MIPS_RLD_VERSION = $70000001;
DT_MIPS_TIME_STAMP = $70000002;
DT_MIPS_ICHECKSUM = $70000003;
DT_MIPS_IVERSION = $70000004;
DT_MIPS_FLAGS = $70000005;
DT_MIPS_BASE_ADDRESS = $70000006;
DT_MIPS_CONFLICT = $70000008;
DT_MIPS_LIBLIST = $70000009;
DT_MIPS_LOCAL_GOTNO = $7000000A;
DT_MIPS_CONFLICTNO = $7000000B;
DT_MIPS_LIBLISTNO = $70000010;
DT_MIPS_SYMTABNO = $70000011;
DT_MIPS_UNREFEXTNO = $70000012;
DT_MIPS_GOTSYM = $70000013;
DT_MIPS_HIPAGENO = $70000014;
DT_MIPS_RLD_MAP = $70000016;
{ values of DT_MIPS_FLAGS }
RHF_QUICKSTART = 1;
RHF_NOTPOT = 2;
{ TLS layout }
TP_OFFSET = $7000;
DTP_OFFSET = $8000;
type
TElfReginfo=record
ri_gprmask: longword;
ri_cprmask: array[0..3] of longword;
ri_gp_value: longint; // signed
end;
TStubHashKey=record
objsec:TObjSection;
offset:aword;
end;
const
relocnames: array[0..50] of PChar = (
'R_MIPS_NONE',
'R_MIPS_16',
'R_MIPS_32',
'R_MIPS_REL32',
'R_MIPS_26',
'R_MIPS_HI16',
'R_MIPS_LO16',
'R_MIPS_GPREL16',
'R_MIPS_LITERAL',
'R_MIPS_GOT16',
'R_MIPS_PC16',
'R_MIPS_CALL16',
'R_MIPS_GPREL32',
nil, {13}
nil, {14}
nil, {15}
nil, {16}
nil, {17}
nil, {18}
nil, {19}
nil, {20}
nil, {21}
'R_MIPS_GOT_HI16',
'R_MIPS_GOT_LO16',
nil, {24}
nil, {25}
nil, {26}
nil, {27}
nil, {28}
nil, {29}
'R_MIPS_CALL_HI16',
'R_MIPS_CALL_LO16',
nil, {32}
nil, {33}
nil, {34}
nil, {35}
nil, {36}
'R_MIPS_JALR',
'R_MIPS_TLS_DTPMOD32',
'R_MIPS_TLS_DTPREL32',
'R_MIPS_TLS_DTPMOD64',
'R_MIPS_TLS_DTPREL64',
'R_MIPS_TLS_GD',
'R_MIPS_TLS_LDM',
'R_MIPS_TLS_DTPREL_HI16',
'R_MIPS_TLS_DTPREL_LO16',
'R_MIPS_TLS_GOTTPREL',
'R_MIPS_TLS_TPREL32',
'R_MIPS_TLS_TPREL64',
'R_MIPS_TLS_TPREL_HI16',
'R_MIPS_TLS_TPREL_LO16'
);
procedure MaybeSwapElfReginfo(var h:TElfReginfo);
var
i: longint;
begin
if source_info.endian<>target_info.endian then
begin
h.ri_gprmask:=swapendian(h.ri_gprmask);
for i:=0 to 3 do
h.ri_cprmask[i]:=swapendian(h.ri_cprmask[i]);
h.ri_gp_value:=swapendian(h.ri_gp_value);
end;
end;
procedure putword(sec:TObjSection;d:longword);
begin
if source_info.endian<>target_info.endian then
d:=swapendian(d);
sec.write(d,4);
end;
{****************************************************************************
ELF Target methods
****************************************************************************}
function elf_mips_encodereloc(objrel:TObjRelocation):byte;
begin
case objrel.typ of
RELOC_NONE:
result:=R_MIPS_NONE;
RELOC_ABSOLUTE:
result:=R_MIPS_32;
RELOC_GOTOFF: {For case jumptables only }
result:=R_MIPS_GPREL32;
else
result:=0;
InternalError(2012110602);
end;
end;
function elf_mips_relocname(reltyp:byte):string;
begin
if (reltyp<=high(relocnames)) and
(relocnames[reltyp]<>nil) then
result:=relocnames[reltyp]
else
result:='unknown ('+tostr(reltyp)+')';
end;
procedure elf_mips_loadreloc(objrel:TObjRelocation);
begin
end;
function elf_mips_loadsection(objinput:TElfObjInput;objdata:TObjData;const shdr:TElfsechdr;shindex:longint):boolean;
var
ri: TElfReginfo;
begin
case shdr.sh_type of
SHT_MIPS_REGINFO:
begin
objinput.ReadBytes(shdr.sh_offset,ri,sizeof(ri));
MaybeSwapElfReginfo(ri);
TElfObjData(objdata).gp_value:=ri.ri_gp_value;
result:=true;
end;
SHT_MIPS_DWARF:
result:=true;
else
writeln('elf_mips_loadsection: ',hexstr(shdr.sh_type,8),' ',objdata.name);
result:=false;
end;
end;
{*****************************************************************************
TElfExeOutputMIPS
*****************************************************************************}
constructor TElfExeOutputMIPS.Create;
begin
inherited Create;
local_got_relocs:=TFPObjectList.Create(False);
pic_stub_syms:=TFPObjectList.Create(False);
pic_stubs:=THashSet.Create(64,True,False);
local_got_slots:=TFPHashObjectList.Create(True);
end;
destructor TElfExeOutputMIPS.Destroy;
begin
local_got_slots.Free;
pic_stub_syms.Free;
pic_stubs.Free;
local_got_relocs.Free;
inherited Destroy;
end;
procedure TElfExeOutputMIPS.CreateGOTSection;
begin
nullstub:=internalobjdata.CObjSymbol.Create(internalobjdata.ObjSymbolList,'*null_pic_stub*');
nullstub.bind:=AB_LOCAL;
nullstub.typ:=AT_FUNCTION;
gotobjsec:=TElfObjSection.create_ext(internalObjData,'.got',
SHT_PROGBITS,SHF_ALLOC or SHF_WRITE or SHF_MIPS_GPREL,sizeof(pint),sizeof(pint));
gotobjsec.SecOptions:=[oso_keep];
{ gotpltobjsec is what's pointed to by DT_PLTGOT }
{ TODO: this is not correct; under some circumstances ld can generate PLTs for MIPS,
using classic model. We'll need to support it, too. }
gotpltobjsec:=TElfObjSection(gotobjsec);
internalObjData.SetSection(gotobjsec);
{ TODO: must be an absolute symbol; binutils use linker script to define it }
gotsymbol:=internalObjData.SymbolDefine('_gp',AB_GLOBAL,AT_NONE);
gotsymbol.offset:=$7ff0;
{ also define _gp_disp and __gnu_local_gp }
gpdispsym:=internalObjData.SymbolDefine('_gp_disp',AB_GLOBAL,AT_NONE);
gnugpsym:=internalObjData.SymbolDefine('__gnu_local_gp',AB_GLOBAL,AT_NONE);
{ reserved entries }
gotobjsec.WriteZeros(sizeof(pint));
putword(gotobjsec,$80000000);
end;
procedure TElfExeOutputMIPS.CreatePLT;
begin
pltobjsec:=TElfObjSection.create_ext(internalObjData,'.plt',
SHT_PROGBITS,SHF_ALLOC or SHF_EXECINSTR,4,16);
pltobjsec.SecOptions:=[oso_keep];
end;
procedure TElfExeOutputMIPS.WriteTargetDynamicTags;
begin
writeDynTag(DT_MIPS_RLD_VERSION,1);
if not IsSharedLibrary then
{writeDynTag(DT_MIPS_RLD_MAP,rldmapsec)};
writeDynTag(DT_MIPS_FLAGS,RHF_NOTPOT);
if IsSharedLibrary then
writeDynTag(DT_MIPS_BASE_ADDRESS,0)
else
writeDynTag(DT_MIPS_BASE_ADDRESS,ElfTarget.exe_image_base);
dt_local_gotno_offset:=dynamicsec.size;
writeDynTag(DT_MIPS_LOCAL_GOTNO,dt_local_gotno_value);
writeDynTag(DT_MIPS_SYMTABNO,dynsymlist.count+1);
{ ABI says: "Index of first external dynamic symbol not referenced locally" }
{ What the hell is this? BFD writes number of output sections(!!),
the values found in actual files do not match even that,
and don't seem to be connected to reality at all... }
//writeDynTag(DT_MIPS_UNREFEXTNO,0);
{Index of first dynamic symbol in GOT }
writeDynTag(DT_MIPS_GOTSYM,dt_gotsym_value+1);
end;
procedure TElfExeOutputMIPS.WritePLTEntry(exesym: TExeSymbol);
begin
end;
function TElfExeOutputMIPS.AllocGOTSlot(objsym:TObjSymbol):boolean;
var
exesym: TExeSymbol;
begin
{ MIPS has quite a different way of allocating GOT slots and dynamic relocations }
result:=false;
exesym:=objsym.exesymbol;
if (exesym=nil) then
InternalError(2013030406);
if exesym.GotOffset>0 then
exit;
make_dynamic_if_undefweak(exesym);
if (exesym.dynindex>0) and (exesym.ObjSymbol.ObjSection=nil) then
begin
{ External symbols must be located at the end of GOT, here just
mark them for dealing later. }
exesym.GotOffset:=high(aword);
exit;
end;
gotobjsec.alloc(sizeof(pint));
exesym.GotOffset:=gotobjsec.size;
result:=true;
end;
function put_externals_last(p1,p2:pointer):longint;
var
sym1: TExeSymbol absolute p1;
sym2: TExeSymbol absolute p2;
begin
result:=ord(sym1.gotoffset=high(aword))-ord(sym2.gotoffset=high(aword));
end;
function address_ascending(p1,p2:pointer):longint;
var
reloc1: TObjRelocation absolute p1;
reloc2: TObjRelocation absolute p2;
begin
result:=(reloc1.symbol.address+reloc1.orgsize)-(reloc2.symbol.address+reloc2.orgsize);
end;
procedure TElfExeOutputMIPS.PrepareGOT;
var
i: longint;
exesym: TExeSymbol;
exesec: TExeSection;
newsec,objsec:TObjSection;
list:TFPObjectList;
begin
inherited PrepareGOT;
{ !! maybe incorrect, where do 'unmapped globals' belong? }
dt_local_gotno_value:=gotobjsec.size div sizeof(pint);
{ Insert PIC stubs (slow...) }
if assigned(trampolinesection) then
begin
exesec:=FindExeSection('.text');
exesec.ObjSectionList.Add(trampolinesection);
trampolinesection.ExeSection:=exesec;
trampolinesection.Used:=true;
end;
for i:=0 to pic_stub_syms.count-1 do
begin
exesym:=TExeSymbol(pic_stub_syms[i]);
newsec:=exesym.stubsymbol.objsection;
objsec:=exesym.objsymbol.objsection;
list:=objsec.ExeSection.ObjSectionList;
list.insert(list.IndexOf(objsec),newsec);
newsec.ExeSection:=objsec.ExeSection;
newsec.Used:=true;
end;
if not dynamiclink then
exit;
{ make room for first R_MIPS_NONE entry }
if dynrelsize>0 then
begin
dynrelocsec.alloc(dynrelocsec.shentsize);
inc(dynrelsize,dynrelocsec.shentsize);
end;
dynsymlist.sort(@put_externals_last);
{ reindex, as sorting could changed the order }
for i:=0 to dynsymlist.count-1 do
TExeSymbol(dynsymlist[i]).dynindex:=i+1;
{ find the symbol to be written as DT_GOTSYM }
for i:=dynsymlist.count-1 downto 0 do
begin
exesym:=TExeSymbol(dynsymlist[i]);
if exesym.gotoffset<>high(aword) then
begin
dt_gotsym_value:=i+1;
break;
end;
end;
{ actually allocate GOT slots for imported symbols }
for i:=dt_gotsym_value to dynsymlist.count-1 do
begin
exesym:=TExeSymbol(dynsymlist[i]);
gotobjsec.alloc(sizeof(pint));
exesym.GotOffset:=gotobjsec.size;
end;
gotsize:=gotobjsec.size;
end;
procedure TElfExeOutputMIPS.Do_Mempos;
var
i:longint;
objrel:TObjRelocation;
addr,page:aword;
numpages,tmp:longint;
objsym:TObjSymbol;
exesym:TExeSymbol;
got_local_area_start:aword;
begin
inherited Do_Mempos;
{ determine required amount of 64k page entries }
local_got_relocs.Sort(@address_ascending);
numpages:=0;
page:=high(aword);
for i:=0 to local_got_relocs.count-1 do
begin
objrel:=TObjRelocation(local_got_relocs[i]);
addr:=objrel.symbol.address+objrel.orgsize;
addr:=addr-smallint(addr);
if (page<>addr shr 16) then
inc(numpages);
page:=addr shr 16;
end;
if (numpages=0) then
exit;
{ An additional page may be consumed when we add slots to GOT }
inc(numpages);
{ Make space in GOT }
got_local_area_start:=dt_local_gotno_value;
inc(gotsize,numpages*sizeof(pint));
gotobjsec.alloc(numpages*sizeof(pint));
{ Redo layout }
inherited Do_Mempos;
{ Now assign GOT offsets to local slots }
SetLength(got_content,numpages);
page:=high(aword);
tmp:=-1;
objsym:=nil;
for i:=0 to local_got_relocs.count-1 do
begin
objrel:=TObjRelocation(local_got_relocs[i]);
addr:=objrel.symbol.address+objrel.orgsize;
{ the contents of slot }
addr:=addr-smallint(addr);
if (page<>addr) then
begin
Inc(tmp);
if (tmp>=numpages) then
InternalError(2013030402);
{ replace relocation symbol with one pointing to GOT slot }
objsym:=CObjSymbol.Create(local_got_slots,hexstr(addr,8));
objsym.offset:=(got_local_area_start+tmp+1)*sizeof(pint);
objsym.bind:=AB_LOCAL;
if (source_info.endian=target_info.endian) then
got_content[tmp]:=addr
else
got_content[tmp]:=swapendian(addr);
page:=addr;
end;
objrel.symbol:=objsym;
end;
if dynamiclink then
begin
{ Patch DT_LOCAL_GOTNO value }
if (dt_local_gotno_offset=0) then
InternalError(2013030401);
i:=dynamicsec.size;
dynamicsec.Data.Seek(dt_local_gotno_offset);
writeDynTag(DT_MIPS_LOCAL_GOTNO,dt_local_gotno_value+numpages);
dynamicsec.size:=i;
{ Increase gotoffset of exesymbols that come after dt_gotsym }
for i:=dt_gotsym_value to dynsymlist.count-1 do
begin
exesym:=TExeSymbol(dynsymlist[i]);
exesym.GotOffset:=exesym.GotOffset+(numpages*sizeof(pint));
end;
end;
end;
procedure TElfExeOutputMIPS.FixupRelocations;
begin
if dynrelsize>0 then
WriteDynRelocEntry(0,R_MIPS_NONE,0,0);
inherited FixupRelocations;
{ Since we omit GOT slots for imported symbols during inherited PrepareGOT, they don't
get written in FixupRelocations either. This must be compensated here. }
gotobjsec.write(got_content[0],length(got_content)*sizeof(pint));
{ TODO: shouldn't be zeroes, but address of stubs if address taken, etc. }
gotobjsec.writeZeros(gotsize-gotobjsec.size);
end;
procedure TElfExeOutputMIPS.MaybeWriteGOTEntry(relocval:aint;objsym:TObjSymbol);
var
gotoff:aword;
begin
if (objsym.bind=AB_LOCAL) then
InternalError(2013030403);
gotoff:=objsym.exesymbol.gotoffset;
if gotoff=0 then
InternalError(2012060902);
{ On MIPS, GOT does not need dynamic relocations }
if gotoff=gotobjsec.Data.size+sizeof(pint) then
begin
if source_info.endian<>target_info.endian then
relocval:=swapendian(relocval);
gotobjsec.write(relocval,sizeof(pint));
end;
end;
procedure TElfExeOutputMIPS.MaybeWriteTLSIEGotEntry(relocval:aint;objsym:TObjSymbol);
var
gotoff,tmp:aword;
begin
gotoff:=objsym.exesymbol.gotoffset;
if gotoff=0 then
InternalError(2012060903);
if gotoff=gotobjsec.Data.size+sizeof(pint) then
begin
tmp:=gotobjsec.mempos+gotoff-sizeof(pint);
if (objsym.exesymbol.dynindex>0) then
begin
gotobjsec.writezeros(sizeof(pint));
dynreloclist.Add(TObjRelocation.CreateRaw(tmp,objsym,R_MIPS_TLS_TPREL32));
end
else
begin
putword(gotobjsec,relocval);
if IsSharedLibrary then
dynreloclist.Add(TObjRelocation.CreateRaw(tmp,nil,R_MIPS_TLS_TPREL32));
end;
end;
end;
procedure TElfExeOutputMIPS.CreatePICStub(objsym:TObjSymbol);
var
textsec,newsec:TObjSection;
newsym:TObjSymbol;
use_trampoline:boolean;
begin
textsec:=objsym.objsection;
use_trampoline:=(objsym.offset>0) or (textsec.SecAlign>16);
if use_trampoline then
begin
if trampolinesection=nil then
trampolinesection:=internalObjData.createsection(sec_code);
newsec:=trampolinesection;
end
else
begin
inc(stubcount);
newsec:=TElfObjSection.create_ext(internalObjData,'.text.stub.'+tostr(stubcount),
SHT_PROGBITS,SHF_ALLOC or SHF_EXECINSTR,0,textsec.SecAlign);
if (newsec.SecAlign>8) then
newsec.WriteZeros(newsec.SecAlign-8);
pic_stub_syms.add(objsym.ExeSymbol);
end;
{ symbol for the stub }
internalObjData.SetSection(newsec);
newsym:=internalObjData.symboldefine('.pic.'+objsym.name,AB_LOCAL,AT_FUNCTION);
putword(newsec,$3c190000); // lui $t9,%hi(x)
newsec.addrawreloc(newsec.size-4,objsym,R_MIPS_HI16);
if use_trampoline then
begin
putword(newsec,$08000000); // j x
newsec.addrawreloc(newsec.size-4,objsym,R_MIPS_26);
end;
putword(newsec,$27390000); // addiu $t9,$t9,%lo(x)
newsec.addrawreloc(newsec.size-4,objsym,R_MIPS_LO16);
objsym.exesymbol.stubsymbol:=newsym;
end;
procedure TElfExeOutputMIPS.GOTRelocPass1(objsec:TObjSection;var idx:longint);
var
objreloc:TObjRelocation;
lowreloc:TObjRelocation;
reltyp:byte;
externsym:boolean;
found:boolean;
i:longint;
lopart,hipart:longword;
objdata:TElfObjData;
exesym:TExeSymbol;
targetsec:TObjSection;
tmp:array[0..2] of longword;
key:TStubHashKey;
entry:PHashSetItem;
begin
objreloc:=TObjRelocation(objsec.ObjRelocations[idx]);
if (ObjReloc.flags and rf_raw)=0 then
reltyp:=ElfTarget.encodereloc(ObjReloc)
else
reltyp:=ObjReloc.ftype;
case reltyp of
R_MIPS_32:
begin
externsym:=assigned(objreloc.symbol) and
assigned(objreloc.symbol.exesymbol) and
(objreloc.symbol.exesymbol.dynindex<>0);
if IsSharedLibrary then
begin
dynrelocsec.alloc(dynrelocsec.shentsize);
objreloc.flags:=objreloc.flags or rf_dynamic;
if (not externsym) then
Inc(relative_reloc_count);
end
end;
R_MIPS_PC16,
R_MIPS_26:
begin
{ Absolute calls into PIC code must go through stubs that load R25 }
exesym:=objreloc.symbol.exesymbol;
if (exesym=nil) or (exesym.dynindex<>0) then
exit;
{ Stub already created? Redirect to it and be done. }
if assigned(exesym.stubsymbol) then
begin
if (exesym.stubsymbol<>nullstub) then
begin
objreloc.symbol.offset:=exesym.stubsymbol.offset;
objreloc.symbol.objsection:=exesym.stubsymbol.objsection;
end;
exit;
end;
targetsec:=exesym.ObjSymbol.objsection;
objdata:=TElfObjData(targetsec.ObjData);
if (objdata.flags and EF_MIPS_PIC)=0 then
exit;
{ Same objdata? then it's responsibility of assembler, not linker }
if (objdata=objsec.objdata) then
exit;
{ Check if destination begins with PIC prologue. If not, mark symbol
with 'null' stub so we don't waste time on subsequent relocs to it. }
targetsec.data.seek(exesym.ObjSymbol.offset);
targetsec.data.read(tmp,3*sizeof(longword));
if (source_info.endian<>target_info.endian) then
for i:=0 to 2 do
tmp[i]:=swapendian(tmp[i]);
if ((tmp[0] and $FFFF0000)<>$3C1C0000) or
((tmp[1] and $FFFF0000)<>$279C0000) or
(tmp[2]<>$0399E021) then
begin
exesym.stubsymbol:=nullstub;
exit;
end;
{ Avoid creating several stubs for an address due to symbol aliasing }
key.objsec:=targetsec;
key.offset:=exesym.ObjSymbol.offset;
entry:=pic_stubs.FindOrAdd(@key,sizeof(TStubHashKey));
if assigned(entry^.Data) then
exesym:=TExeSymbol(entry^.Data)
else
begin
entry^.Data:=exesym;
CreatePICStub(exesym.objsymbol);
end;
objreloc.symbol.offset:=exesym.stubsymbol.offset;
objreloc.symbol.objsection:=exesym.stubsymbol.objsection;
end;
R_MIPS_CALL16,
R_MIPS_GOT16:
begin
if objreloc.symbol.bind<>AB_LOCAL then
AllocGOTSlot(objreloc.symbol)
else
begin
{ Extract the addend, which is stored split between this relocation and
the following (maybe not immediately) R_MIPS_LO16 one. }
found:=false;
for i:=idx+1 to objsec.ObjRelocations.Count-1 do
begin
lowreloc:=TObjRelocation(objsec.ObjRelocations[i]);
if (lowreloc.flags and rf_raw)=0 then
InternalError(2013030101);
if (lowreloc.ftype=R_MIPS_LO16) then
begin;
found:=true;
objsec.Data.Seek(objreloc.DataOffset);
objsec.Data.Read(hipart,sizeof(hipart));
objsec.Data.Seek(lowreloc.DataOffset);
objsec.Data.Read(lopart,sizeof(lopart));
break;
end;
end;
if not found then
InternalError(2013030102);
if (source_info.endian<>target_info.endian) then
begin
hipart:=swapendian(hipart);
lopart:=swapendian(lopart);
end;
objreloc.orgsize:=(hipart shl 16)+SmallInt(lopart);
local_got_relocs.add(objreloc);
end;
end;
R_MIPS_TLS_GOTTPREL:
inherited AllocGOTSlot(objreloc.symbol);
end;
end;
type
PRelocData=^TRelocData;
TRelocData=record
next:PRelocData;
objsec:TObjSection;
objrel:TObjRelocation;
addend:aint;
end;
procedure TElfExeOutputMIPS.DoRelocationFixup(objsec:TObjSection);
var
i,zero:longint;
objreloc: TObjRelocation;
AHL_S,
tmp,
address,
relocval : aint;
relocsec : TObjSection;
data: TDynamicArray;
reltyp: byte;
curloc: aword;
reloclist,hr: PRelocData;
is_gp_disp: boolean;
begin
data:=objsec.data;
reloclist:=nil;
for i:=0 to objsec.ObjRelocations.Count-1 do
begin
objreloc:=TObjRelocation(objsec.ObjRelocations[i]);
case objreloc.typ of
RELOC_NONE:
continue;
RELOC_ZERO:
begin
data.Seek(objreloc.dataoffset);
zero:=0;
data.Write(zero,4);
continue;
end;
end;
if (objreloc.flags and rf_raw)=0 then
reltyp:=ElfTarget.encodereloc(objreloc)
else
reltyp:=objreloc.ftype;
if (oso_rela_relocs in objsec.SecOptions) then
address:=objreloc.orgsize
else
begin
data.Seek(objreloc.dataoffset);
data.Read(address,4);
if source_info.endian<>target_info.endian then
address:=swapendian(address);
end;
if assigned(objreloc.symbol) then
begin
relocsec:=objreloc.symbol.objsection;
relocval:=objreloc.symbol.address;
end
else if assigned(objreloc.objsection) then
begin
relocsec:=objreloc.objsection;
relocval:=objreloc.objsection.mempos
end
else
internalerror(2012060702);
{ Only debug sections are allowed to have relocs pointing to unused sections }
if assigned(relocsec) and not (relocsec.used and assigned(relocsec.exesection)) and
not (oso_debug in objsec.secoptions) then
begin
writeln(objsec.fullname,' references ',relocsec.fullname);
internalerror(2012060703);
end;
curloc:=objsec.mempos+objreloc.dataoffset;
if (relocsec=nil) or (relocsec.used) then
case reltyp of
R_MIPS_32:
begin
address:=address+relocval;
if (objreloc.flags and rf_dynamic)<>0 then
begin
if (objreloc.symbol=nil) or
(objreloc.symbol.exesymbol=nil) or
(objreloc.symbol.exesymbol.dynindex=0) then
WriteDynRelocEntry(curloc,R_MIPS_REL32,0,address)
else
dynreloclist.add(TObjRelocation.CreateRaw(curloc,objreloc.symbol,R_MIPS_REL32));
end;
end;
R_MIPS_26:
begin
tmp:=(address and $03FFFFFF) shl 2;
tmp:=((tmp or (curloc and $F0000000))+relocval) shr 2;
{ TODO: Report overflow if upper 4 bits change
However JAL to undefined weak symbol is not treated as an overflow }
address:=(address and $FC000000) or (tmp and $3FFFFFF);
end;
R_MIPS_HI16:
begin
{ This relocation can be handled only after seeing a matching LO16 one,
moreover BFD supports any number of HI16 to precede a single LO16.
So just add it to a queue. }
new(hr);
hr^.next:=reloclist;
hr^.objrel:=objreloc;
hr^.objsec:=objsec;
hr^.addend:=address; //TODO: maybe it can be saved in objrel.orgsize field
reloclist:=hr;
end;
R_MIPS_LO16:
begin
{ LO16 may be without pair, e.g. in following sequence:
lui $v0, %hi(foo)
lw $a0, %lo(foo)($v0)
lw $a1, %lo(foo+4)($v0)
}
AHL_S:=SmallInt(address)+relocval;
is_gp_disp:=false;
while assigned(reloclist) do
begin
hr:=reloclist;
reloclist:=hr^.next;
// if relocval<>hr^.relocval then // must be the same symbol
// InternalError();
{ _gp_disp and __gnu_local_gp magic }
if assigned(hr^.objrel.symbol) and
(hr^.objrel.symbol.bind<>AB_LOCAL) then
begin
is_gp_disp:=(hr^.objrel.symbol.exesymbol.objsymbol=gpdispsym);
if (hr^.objrel.symbol.exesymbol.objsymbol=gnugpsym) then
relocval:=gotsymbol.address;
end;
{ in case of _gp_disp, non-zero addend is not possible? }
{ 4 must be added right here, so possible overflow in low half
is propagated into high one (e.g if displacement is $37ffc,
high part must be 4, not 3) }
if is_gp_disp then
relocval:=gotsymbol.address-curloc+4;
AHL_S:=(hr^.addend shl 16)+SmallInt(address)+relocval;
case hr^.objrel.ftype of
R_MIPS_HI16:
tmp:=(AHL_S-SmallInt(AHL_S)) shr 16;
R_MIPS_GOT16:
tmp:=-(gotsymbol.offset-(hr^.objrel.symbol.offset-sizeof(pint)));
else
InternalError(2013030404);
end;
tmp:=(hr^.addend and $FFFF0000) or (tmp and $FFFF);
data.seek(hr^.objrel.dataoffset);
if source_info.endian<>target_info.endian then
tmp:=swapendian(tmp);
data.Write(tmp,4);
dispose(hr);
end;
address:=(address and $FFFF0000) or (AHL_S and $FFFF);
end;
R_MIPS_CALL16,
R_MIPS_GOT16:
begin
{ GOT16 relocations against local symbols are followed by LO16 }
if (objreloc.symbol.bind=AB_LOCAL) then
begin
new(hr);
hr^.next:=reloclist;
hr^.objrel:=objreloc;
hr^.objsec:=objsec;
hr^.addend:=address; //TODO: maybe it can be saved in objrel.orgsize field
reloclist:=hr;
continue;
end;
MaybeWriteGOTEntry(relocval,objreloc.symbol);
// !! this is correct only while _gp symbol is defined relative to .got !!
relocval:=-(gotsymbol.offset-(objreloc.symbol.exesymbol.gotoffset-sizeof(pint)));
// TODO: check overflow
address:=(address and $FFFF0000) or (relocval and $FFFF);
end;
R_MIPS_PC16:
begin
tmp:=((SmallInt(address) shl 2)+relocval-curloc) shr 2;
if (tmp<>SmallInt(tmp)) then
ReportRelocOverflow(reltyp,objsec,objreloc);
address:=(address and $FFFF0000) or (tmp and $FFFF);
end;
R_MIPS_GPREL32:
address:=address+relocval+TElfObjData(objsec.objdata).gp_value-gotsymbol.address;
R_MIPS_TLS_GOTTPREL:
begin
if IsSharedLibrary then
relocval:=relocval-tlsseg.MemPos
else
relocval:=relocval-(tlsseg.MemPos+TP_OFFSET);
MaybeWriteTLSIEGotEntry(relocval,objreloc.symbol);
relocval:=-(gotsymbol.offset-(objreloc.symbol.exesymbol.gotoffset-sizeof(pint)));
// TODO: check overflow
address:=(address and $FFFF0000) or (relocval and $FFFF);
end;
R_MIPS_TLS_TPREL_HI16:
begin
tmp:=SmallInt(address)+relocval-(tlsseg.MemPos+TP_OFFSET);
tmp:=(tmp+$8000) shr 16;
address:=(address and $FFFF0000) or (tmp and $FFFF);
end;
R_MIPS_TLS_TPREL_LO16:
begin
tmp:=SmallInt(address)+relocval-(tlsseg.MemPos+TP_OFFSET);
address:=(address and $FFFF0000) or (tmp and $FFFF);
end;
R_MIPS_JALR: {optimization hint}
begin
{ 4 is subtracted because branch is relative to delay slot, not instruction itself }
tmp:=(relocval-curloc-4) shr 2;
if (tmp=SmallInt(tmp)) then
begin
if (address=$0320f809) then { JALR $t9 -> BAL addr }
address:=$04110000 or (tmp and $FFFF)
else if (address=$03200008) then { JR $t9 -> B addr }
address:=$10000000 or (tmp and $FFFF);
end;
end;
else
begin
writeln(objsec.fullname,'+',objreloc.dataoffset,' ',objreloc.ftype);
internalerror(200604014);
end;
end
else { not relocsec.Used }
address:=0; { Relocation in debug section points to unused section, which is eliminated by linker }
data.Seek(objreloc.dataoffset);
if source_info.endian<>target_info.endian then
address:=swapendian(address);
data.Write(address,4);
end;
end;
{*****************************************************************************
Initialize
*****************************************************************************}
const
elf_target_mips: TElfTarget =
(
max_page_size: $10000;
exe_image_base: $400000;
machine_code: EM_MIPS;
relocs_use_addend: false;
dyn_reloc_codes: (
0,
0,
0,
0,
0
);
relocname: @elf_mips_relocName;
encodereloc: @elf_mips_encodeReloc;
loadreloc: @elf_mips_loadReloc;
loadsection: @elf_mips_loadSection;
encodeflags: nil;
);
initialization
ElfTarget:=elf_target_mips;
ElfExeOutputClass:=TElfExeOutputMIPS;
end.
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