mirror of
https://github.com/samsonjs/compiler.git
synced 2026-03-25 08:45:52 +00:00
support relocation info
This commit is contained in:
Sami Samhuri
parent
0269598c16
commit
ce1f5bb4dc
1 changed files with 57 additions and 50 deletions
|
|
@ -8,16 +8,20 @@ module Assembler
|
|||
|
||||
attr_accessor :header, :load_commands, :sections, :data
|
||||
attr_accessor :current_segment
|
||||
attr_accessor :text_offset
|
||||
|
||||
def initialize(filetype=MH_OBJECT)
|
||||
@header = MachHeader.new(MH_MAGIC, CPU_TYPE_X86, CPU_SUBTYPE_X86_ALL, filetype, 0, 0, 0)
|
||||
@load_commands = [] # All defined segments.
|
||||
@sections = {} # Map of segment names to lists of segments.
|
||||
@sections = {} # Map of segment names to lists of sections.
|
||||
@section_disk_size = Hash.new(0) # Sections store their VM size so we need their sizes on disk.
|
||||
@section_offset = 0 # Offset of the next section's data, in bytes.
|
||||
@data = [] # Blobs of data that appear at the end of the file.
|
||||
# (text, data, symtab, ...)
|
||||
# (text, data, relocation info, symtab, ...)
|
||||
@current_segment = nil # An alias for the last defined segment.
|
||||
@text_segname = nil # Name of __TEXT segement
|
||||
@text_sect_index = nil # Index of __text section
|
||||
@text_data_index = nil # Index into @data of __text section data
|
||||
@reloc_info = nil # Copy of relocation info array
|
||||
end
|
||||
|
||||
|
||||
|
|
@ -82,11 +86,12 @@ module Assembler
|
|||
segment=@current_segment, type=S_REGULAR)
|
||||
|
||||
# Create the new section.
|
||||
section = Section.new(name, segname, 0, vmsize, 0, 0, 0, 0, 0, 0, type)
|
||||
section = Section.new(name, segname, @section_offset, vmsize, 0, 0, 0, 0, 0, 0, type)
|
||||
|
||||
# Add this section to the map of segment names to sections.
|
||||
(@sections[segment[:segname]] ||= []) << section
|
||||
@section_disk_size[name] = data.size
|
||||
@section_offset += data.size
|
||||
@data << data if data.size > 0
|
||||
|
||||
# Update the header.
|
||||
|
|
@ -116,20 +121,32 @@ module Assembler
|
|||
# name given (__TEXT).
|
||||
|
||||
def text(data, sectname='__text', segname='__TEXT')
|
||||
real_segname = nil
|
||||
unless @current_segment
|
||||
segment(segname_based_on_filetype(segname)) do |seg|
|
||||
real_segname = segname_based_on_filetype(segname)
|
||||
segment(real_segname) do |seg|
|
||||
seg[:maxprot] = VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE
|
||||
seg[:initprot] = VM_PROT_READ | VM_PROT_EXECUTE
|
||||
end
|
||||
end
|
||||
|
||||
section(sectname, segname, data) do |sect|
|
||||
# reloff and nreloc are calculated later (in calculate_offsets)
|
||||
sect[:flags] = 0x400 # S_ATTR_SOME_INSTRUCTIONS
|
||||
end
|
||||
|
||||
# Remember where section and data are so we can update them later.
|
||||
@text_segname = real_segname || segname
|
||||
@text_sect_index = @sections[@text_segname].length-1
|
||||
@text_data_index = @data.length-1
|
||||
|
||||
return self
|
||||
end
|
||||
|
||||
def update_text(data)
|
||||
raise 'no __text segment defined yet' unless @text_data_index
|
||||
@data[@text_data_index] = data
|
||||
end
|
||||
|
||||
# Basis for #data, #const, and #bss methods.
|
||||
def segment_based_on_filetype(segname, options={})
|
||||
|
|
@ -173,6 +190,19 @@ module Assembler
|
|||
end
|
||||
end
|
||||
|
||||
# Define a relocation table. Usually between segments and the
|
||||
# symbol table.
|
||||
#
|
||||
# Accepts an array of relocation info structs.
|
||||
def reloc(reloc_info)
|
||||
@data << if reloc_info.respond_to?(:join)
|
||||
reloc_info.map {|r| r.serialize}.join
|
||||
else
|
||||
reloc_info
|
||||
end
|
||||
@reloc_info = reloc_info.map {|x| x.clone}
|
||||
return self
|
||||
end
|
||||
|
||||
# Define a symbol table. This should usually be placed at the end of the
|
||||
# file.
|
||||
|
|
@ -204,7 +234,6 @@ module Assembler
|
|||
|
||||
@data << nlist_ary.map {|n| n.serialize}.join
|
||||
@data << stab
|
||||
|
||||
return self
|
||||
end
|
||||
|
||||
|
|
@ -218,63 +247,34 @@ module Assembler
|
|||
|
||||
# Now that we have all the pieces of the file defined we can calculate
|
||||
# the file offsets of segments and sections.
|
||||
recalculate_offsets
|
||||
|
||||
|
||||
# |------------------|
|
||||
# | Mach Header | Part 1
|
||||
# |------------------|
|
||||
# | Segment 1 | Part 2
|
||||
# | Section 1 | ---
|
||||
# | Section 2 | --|--
|
||||
# | ... | | |
|
||||
# | Segment 2 | | |
|
||||
# | Section 4 | | |
|
||||
# | Section 5 | | |
|
||||
# | ... | | |
|
||||
# | ... | | |
|
||||
# | [Symtab cmd] | | |
|
||||
# |------------------| | |
|
||||
# | Section data 1 | <-- | Part 3
|
||||
# | Section data 2 | <----
|
||||
# | ... |
|
||||
# | [Symtab data] |
|
||||
# |------------------|
|
||||
calculate_offsets
|
||||
|
||||
###################################
|
||||
# Mach-O file Part 1: Mach Header #
|
||||
###################################
|
||||
|
||||
obj = @header.serialize
|
||||
|
||||
@header.serialize +
|
||||
|
||||
#####################################
|
||||
# Mach-O file Part 2: Load Commands #
|
||||
#####################################
|
||||
|
||||
# dump each load command (which include the section headers under them)
|
||||
obj += @load_commands.map do |cmd|
|
||||
@load_commands.map do |cmd|
|
||||
sects = @sections[cmd[:segname]] rescue []
|
||||
sects.inject(cmd.serialize) do |data, sect|
|
||||
data + sect.serialize
|
||||
end
|
||||
end.join
|
||||
|
||||
end.join +
|
||||
|
||||
###################################
|
||||
# Mach-O file Part 3: Binary data #
|
||||
###################################
|
||||
|
||||
obj += @data.join
|
||||
|
||||
|
||||
return obj
|
||||
@data.join
|
||||
end
|
||||
|
||||
|
||||
# Update the file offsets in segments and sections.
|
||||
|
||||
def recalculate_offsets
|
||||
def calculate_offsets
|
||||
|
||||
# Maintain the offset into the the file on disk. This is used
|
||||
# to update the various structures.
|
||||
|
|
@ -317,7 +317,7 @@ module Assembler
|
|||
|
||||
# Second pass over load commands. Fill in file offsets.
|
||||
@load_commands.each do |cmd|
|
||||
case cmd[:cmd]\
|
||||
case cmd[:cmd]
|
||||
|
||||
when LC_SEGMENT
|
||||
seg = cmd
|
||||
|
|
@ -329,6 +329,13 @@ module Assembler
|
|||
end
|
||||
|
||||
when LC_SYMTAB
|
||||
if @reloc_info
|
||||
# update text section with relocation info
|
||||
__text = @sections[@text_segname][@text_sect_index]
|
||||
__text[:reloff] = offset
|
||||
__text[:nreloc] = @reloc_info.length
|
||||
offset += @reloc_info.first.bytesize * @reloc_info.length
|
||||
end
|
||||
st = cmd
|
||||
st[:symoff] = offset
|
||||
offset += st[:nsyms] * Nlist.bytesize
|
||||
|
|
@ -342,7 +349,7 @@ module Assembler
|
|||
|
||||
end # @load_commands.each
|
||||
|
||||
end # def recalculate_offsets
|
||||
end # def calculate_offsets
|
||||
|
||||
|
||||
#######
|
||||
|
|
@ -354,7 +361,7 @@ module Assembler
|
|||
when MH_OBJECT: ''
|
||||
when MH_EXECUTE: segname
|
||||
else
|
||||
raise "unsupported MachO file type! #{@header.inspect}"
|
||||
raise "unsupported MachO file type: #{@header.inspect}"
|
||||
end
|
||||
end
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue