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-- Binary file execute in memory handler.
-- Copyright (C) 2006 - 2015 Tristan Gingold
--
-- 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, see <gnu.org/licenses>.
with Ada.Text_IO; use Ada.Text_IO;
package body Binary_File.Memory is
-- Absolute section.
Sect_Abs : Section_Acc;
-- PLT section (for x86-64).
Sect_Plt : Section_Acc;
procedure Set_Symbol_Address (Sym : Symbol; Addr : System.Address) is
begin
if Arch = Arch_X86_64 and then Is_Symbol_Code (Sym) then
-- Branches are limited on x86-64 to a 32 bit offset. Create a
-- trampoline so that functions created outside of the module could
-- be reached using the standard ABI.
--
-- This works only for code, not for data. Therefore we assume that
-- data symbols are correctly handled.
declare
V : Unsigned_64;
Pc : constant Pc_Type := Sect_Plt.Pc;
begin
Set_Current_Section (Sect_Plt);
Prealloc (16);
-- Emit: movabs $ADDR, %r11
V := Unsigned_64 (To_Pc_Type (Addr));
Sect_Plt.Data (Pc + 0) := 16#49#;
Sect_Plt.Data (Pc + 1) := 16#BB#;
for I in Pc_Type range 0 .. 7 loop
Sect_Plt.Data (Pc + 2 + I) := Byte (V and 16#ff#);
V := Shift_Right (V, 8);
end loop;
-- Emit: jmp *%r11
Sect_Plt.Data (Pc + 10) := 16#41#;
Sect_Plt.Data (Pc + 11) := 16#FF#;
Sect_Plt.Data (Pc + 12) := 16#E3#;
Sect_Plt.Pc := Pc + 13;
Set_Symbol_Value (Sym, Pc);
Set_Section (Sym, Sect_Plt);
end;
else
Set_Symbol_Value (Sym, To_Pc_Type (Addr));
Set_Section (Sym, Sect_Abs);
end if;
-- Symbol is not anymore undefined.
Set_Scope (Sym, Sym_Global);
end Set_Symbol_Address;
procedure Write_Memory_Init is
begin
Create_Section (Sect_Abs, "*ABS*", Section_Exec);
Sect_Abs.Vaddr := 0;
if Arch = Arch_X86_64 then
Create_Section (Sect_Plt, ".plt", Section_Exec);
end if;
end Write_Memory_Init;
type Segment_Kind is (Seg_Text, Seg_Ro, Seg_Data, Seg_None);
function Get_Segment (Sect : Section_Acc) return Segment_Kind is
begin
if Sect = Sect_Abs then
return Seg_None;
end if;
if (Sect.Flags and Section_Exec) /= 0 then
return Seg_Text;
elsif (Sect.Flags and Section_Write) /= 0 then
return Seg_Data;
elsif (Sect.Flags and Section_Read) /= 0 then
return Seg_Ro;
else
return Seg_None;
end if;
end Get_Segment;
procedure Write_Memory_Relocate (Error : out Boolean)
is
Log_Pagesize : constant := 12;
type Seg_Size_Array is array (Segment_Kind) of Pc_Type;
Seg_Size : Seg_Size_Array;
Seg_Offs : Seg_Size_Array;
Size : Pc_Type;
Program_Seg : Memsegs.Memseg_Type;
Program : Byte_Array_Acc;
Sect : Section_Acc;
Rel : Reloc_Acc;
N_Rel : Reloc_Acc;
begin
-- Compute sizes.
Seg_Size := (others => 0);
Sect := Section_Chain;
while Sect /= null loop
declare
Seg : constant Segment_Kind := Get_Segment (Sect);
begin
Seg_Size (Seg) :=
Pow_Align (Seg_Size (Seg), Sect.Align) + Sect.Pc;
end;
Sect := Sect.Next;
end loop;
-- Align.
for I in Seg_Text .. Seg_Data loop
Seg_Size (I) := Pow_Align (Seg_Size (I), Log_Pagesize);
end loop;
-- Whole size.
Size := 0;
for I in Seg_Text .. Seg_Data loop
Size := Size + Seg_Size (I);
end loop;
-- Allocate and copy.
Program_Seg := Memsegs.Create;
Memsegs.Resize (Program_Seg, Natural (Size));
Program := To_Byte_Array_Acc (Memsegs.Get_Address (Program_Seg));
Seg_Offs (Seg_Text) := 0;
Seg_Offs (Seg_Ro) := Seg_Size (Seg_Text);
Seg_Offs (Seg_Data) := Seg_Size (Seg_Text) + Seg_Size (Seg_Ro);
Sect := Section_Chain;
while Sect /= null loop
declare
Seg : constant Segment_Kind := Get_Segment (Sect);
Off : Pc_Type renames Seg_Offs (Seg);
begin
if Seg /= Seg_None then
if Sect.Pc > 0 then
Off := Pow_Align (Off, Sect.Align);
if Sect.Data = null then
-- For bss.
Program (Off .. Off + Sect.Pc - 1) := (others => 0);
else
Program (Off .. Off + Sect.Pc - 1) :=
Sect.Data (0 .. Sect.Pc - 1);
Memsegs.Delete (Sect.Seg);
end if;
Sect.Data := To_Byte_Array_Acc (Program (Off)'Address);
-- Set virtual address.
Sect.Vaddr := To_Pc_Type (Program (Off)'Address);
Off := Off + Sect.Pc;
end if;
end if;
end;
Sect := Sect.Next;
end loop;
-- Do all relocations.
Sect := Section_Chain;
Error := False;
while Sect /= null loop
-- Put_Line ("Section: " & Sect.Name.all & ", Flags:"
-- & Section_Flags'Image (Sect.Flags));
Rel := Sect.First_Reloc;
while Rel /= null loop
N_Rel := Rel.Sect_Next;
if Get_Scope (Rel.Sym) = Sym_Undef then
Put_Line ("symbol " & Get_Symbol_Name (Rel.Sym)
& " is undefined");
Error := True;
else
Apply_Reloc (Sect, Rel);
end if;
Free (Rel);
Rel := N_Rel;
end loop;
Sect.First_Reloc := null;
Sect.Last_Reloc := null;
Sect.Nbr_Relocs := 0;
Sect := Sect.Next;
end loop;
if Seg_Size (Seg_Text) /= 0 then
Memsegs.Set_Rx (Program_Seg, 0, Natural (Seg_Size (Seg_Text)));
end if;
end Write_Memory_Relocate;
function Get_Section_Addr (Sect : Section_Acc) return System.Address is
begin
return Sect.Data (0)'Address;
end Get_Section_Addr;
function Get_Section_Size (Sect : Section_Acc) return Pc_Type is
begin
return Sect.Pc;
end Get_Section_Size;
end Binary_File.Memory;
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