44module native
55
66import os
7+ import ast
78
89const elf_class32 = 1
910const elf_class64 = 2
300301 size i64 // Symbol size.
301302}
302303
304+ // see for more details: https://gist.github.com/x0nu11byt3/bcb35c3de461e5fb66173071a2379779
305+ // https://www.etherington.xyz/elfguide#symtab-section-entries
303306fn (mut g Gen) create_symbol_table_section (str_name string , info u8 , bind u8 , other i8 , value i64 , size i64 ,
304307 shndx i16 ) SymbolTableSection {
305308 return SymbolTableSection{
@@ -615,7 +618,6 @@ fn (mut g Gen) gen_section_data(sections []Section) {
615618 for rela in data {
616619 g.write64 (rela.offset)
617620 g.fn_addr[rela.name] = rela.offset // that's wierd it's the call offset, not the fn
618- g.fn_names << rela.name
619621 g.write64 (rela.info)
620622 g.write64 (rela.addend)
621623 g.println ('; SHT_RELA `${rela.name} ` (${rela.offset} , ${rela.info} , ${rela.addend} )' )
@@ -711,6 +713,23 @@ pub fn (mut g Gen) generate_linkable_elf_header() {
711713 elf_stv_default, 0 , 0 , 0 ),
712714 ]
713715
716+ mut sym_data_offset := 0 // offset from the beggining of the data section
717+ for f in g.files {
718+ for s in f.stmts {
719+ if s is ast.GlobalDecl {
720+ for fi in s.fields {
721+ size := g.get_type_size (fi.typ)
722+ if size > 0 {
723+ g.symbol_table << g.create_symbol_table_section (fi.name, elf_stt_object,
724+ elf_stb_global, elf_stv_default, sym_data_offset, size, i16 (g.find_section_header ('.data' ,
725+ sections)))
726+ }
727+ sym_data_offset + = size
728+ }
729+ }
730+ }
731+ }
732+
714733 for symbol in g.extern_symbols {
715734 g.symbol_table << g.create_symbol_table_section (symbol[2 ..], elf_stt_notype, elf_stb_global,
716735 elf_stv_default, 0 , 0 , 0 )
@@ -742,6 +761,37 @@ pub fn (mut g Gen) generate_linkable_elf_header() {
742761
743762 g.elf_rela_section = sections[g.find_section_header ('.rela.text' , sections)]
744763
764+ // Init data section
765+ // TODO: use .bss for uninitialized data or generate the data
766+ data_section := sections[g.find_section_header ('.data' , sections)]
767+ g.elf_data_header_addr = data_section.header.offset
768+
769+ data_pos := g.pos ()
770+ g.println ('\n data_start_pos = ${data_pos.hex()} ' )
771+ g.write64_at (g.elf_data_header_addr + 24 , data_pos)
772+ for f in g.files {
773+ for s in f.stmts {
774+ if s is ast.GlobalDecl {
775+ for fi in s.fields {
776+ size := g.get_type_size (fi.typ)
777+ match size {
778+ 1 { g.write8 (0xF ) }
779+ 2 { g.write16 (0xF ) }
780+ 4 { g.write32 (0xF ) }
781+ 8 { g.write64 (i64 (0xF )) }
782+ else { println ('${@LOCATION} unsupported size ${size} for global ${fi} ' ) }
783+ }
784+ g.println ('; global ${fi.name} , size: ${size} ' )
785+ }
786+ }
787+ }
788+ }
789+ g.write64_at (g.elf_data_header_addr + 32 , g.pos () - data_pos)
790+ // TODO: pre-calculate .data instead of genetating it at runtime
791+
792+ // It is wierd, the init section has something in it but I did not find
793+ // where does it come from
794+
745795 // user code starts here
746796 if g.pref.is_verbose {
747797 eprintln ('code_start_pos = ${g.buf.len.hex()} ' )
@@ -752,11 +802,29 @@ pub fn (mut g Gen) generate_linkable_elf_header() {
752802 // if g.start_symbol_addr > 0 {
753803 // g.write64_at(g.start_symbol_addr + native.elf_symtab_size - 16, g.code_start_pos)
754804 // }
755-
756805 text_section := sections[g.find_section_header ('.text' , sections)]
757806 g.elf_text_header_addr = text_section.header.offset
758807 g.write64_at (g.elf_text_header_addr + 24 , g.pos ()) // write the code start pos to the text section
759808
809+ g.println ('; fill .data' )
810+ for f in g.files {
811+ for s in f.stmts {
812+ if s is ast.GlobalDecl {
813+ for fi in s.fields {
814+ size := g.get_type_size (fi.typ)
815+ if size > 8 || size < = 0 {
816+ println ('${@LOCATION} unsupported size ${size} for global ${fi} ' )
817+ } else if fi.expr ! is ast.EmptyExpr {
818+ g.expr (fi.expr)
819+ g.code_gen.mov_reg_to_var (GlobalVar{fi.name, fi.typ}, g.code_gen.main_reg ())
820+ g.println ('; global ${fi.name} , size: ${size} ' )
821+ }
822+ }
823+ }
824+ }
825+ }
826+
827+ g.elf_main_call_pos = g.pos ()
760828 g.code_gen.call (placeholder)
761829 g.println ('; call main.main' )
762830 g.code_gen.mov64 (g.code_gen.main_reg (), i64 (0 ))
@@ -848,9 +916,13 @@ pub fn (mut g Gen) gen_rela_section() {
848916 g.symtab_get_index (g.symbol_table, symbol[2 ..]), elf_r_amd64_ gotpcrelx, - 4 )
849917 }
850918 for var_pos, symbol in g.extern_vars {
851- relocations << g.create_rela_section (symbol, var_pos - g.code_start_pos + 2 , g.symtab_get_index (g.symbol_table,
919+ relocations << g.create_rela_section (symbol, var_pos - g.code_start_pos, g.symtab_get_index (g.symbol_table,
852920 symbol[2 ..]), elf_r_amd64_64 , 0 )
853921 }
922+ for var_pos, symbol in g.global_vars {
923+ relocations << g.create_rela_section (symbol, var_pos - g.code_start_pos, g.symtab_get_index (g.symbol_table,
924+ symbol), elf_r_amd64_64 , 0 )
925+ }
854926 g.elf_rela_section.data = relocations
855927 g.gen_section_data ([g.elf_rela_section])
856928}
@@ -872,15 +944,15 @@ pub fn (mut g Gen) generate_elf_footer() {
872944 g.write64_at (g.file_size_pos + 8 , file_size)
873945 if g.pref.arch == .arm64 {
874946 bl_next := u32 (0x94000001 )
875- g.write32_at (g.code_start_pos , i32 (bl_next))
947+ g.write32_at (g.elf_main_call_pos , i32 (bl_next))
876948 } else {
877949 // amd64
878950 // call main function, it's not guaranteed to be the first
879951 // we generated call(0) ("e8 0")
880952 // now need to replace "0" with a relative address of the main function
881953 // +1 is for "e8"
882954 // -5 is for "e8 00 00 00 00"
883- g.write32_at (g.code_start_pos + 1 , i32 (g.main_fn_addr - g.code_start_pos ) - 5 )
955+ g.write32_at (g.elf_main_call_pos + 1 , i32 (g.main_fn_addr - g.elf_main_call_pos ) - 5 )
884956 }
885957 g.create_executable ()
886958}
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