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Decipher .debug_abbrev

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David Gonzalez Martin 2024-09-18 17:54:46 -06:00 committed by David
parent ba4c5e691c
commit 9d310e36e4
1 changed files with 77 additions and 7 deletions
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84
bootstrap/main.c
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@ -7857,6 +7857,28 @@ fn void dwarf_playground(Thread* thread)
assert(*debug_info_bytes.pointer == 0);
}
STRUCT(DwarfAttributeFormPair)
{
DwarfAttribute attribute;
DwarfForm form;
};
declare_slice(DwarfAttributeFormPair);
fn void encode_attribute_abbreviations(ELFBuilder* restrict builder, Slice(DwarfAttributeFormPair) attributes)
{
auto* restrict buffer = &builder->file;
for (u64 i = 0; i < attributes.length; i += 1)
{
auto pair = attributes.pointer[i];
uleb128_encode(buffer, pair.attribute);
uleb128_encode(buffer, pair.form);
}
uleb128_encode(buffer, 0);
uleb128_encode(buffer, 0);
}
may_be_unused fn void write_elf(Thread* thread, const ObjectOptions* const restrict options, char** envp)
{
unused(thread);
@ -9437,16 +9459,64 @@ may_be_unused fn void write_elf(Thread* thread, const ObjectOptions* const restr
auto name = elf_get_section_name(builder, strlit(".debug_abbrev"));
u8 data[] = {
0x01, 0x11, 0x01, 0x25, 0x25, 0x13, 0x05, 0x03, 0x25, 0x72, 0x17, 0x10, 0x17, 0x1B, 0x25, 0x11,
0x1B, 0x12, 0x06, 0x73, 0x17, 0x00, 0x00, 0x02, 0x2E, 0x00, 0x11, 0x1B, 0x12, 0x06, 0x40, 0x18,
0x7A, 0x19, 0x03, 0x25, 0x3A, 0x0B, 0x3B, 0x0B, 0x49, 0x13, 0x3F, 0x19, 0x00, 0x00, 0x03, 0x24,
0x00, 0x03, 0x25, 0x3E, 0x0B, 0x0B, 0x0B, 0x00, 0x00, 0x00,
// Abbreviation entry
uleb128_encode(&builder->file, 1);
// Abbreviation kind
uleb128_encode(&builder->file, DW_TAG_compile_unit);
// Has children
*vb_add(&builder->file, 1) = 1;
DwarfAttributeFormPair compile_unit[] = {
{ DW_AT_producer, DW_FORM_strx1, },
{ DW_AT_language, DW_FORM_data2, },
{ DW_AT_name, DW_FORM_strx1, },
{ DW_AT_str_offsets_base, DW_FORM_sec_offset, },
{ DW_AT_stmt_list, DW_FORM_sec_offset, },
{ DW_AT_comp_dir, DW_FORM_strx1, },
{ DW_AT_low_pc, DW_FORM_addrx, },
{ DW_AT_high_pc, DW_FORM_data4, },
{ DW_AT_addr_base, DW_FORM_sec_offset, },
};
encode_attribute_abbreviations(builder, (Slice(DwarfAttributeFormPair)) array_to_slice(compile_unit));
// Abbreviation entry
uleb128_encode(&builder->file, 2);
// Abbreviation kind
uleb128_encode(&builder->file, DW_TAG_subprogram);
// Has children
*vb_add(&builder->file, 1) = 0;
auto size = sizeof(data);
DwarfAttributeFormPair subprogram[] = {
{ DW_AT_low_pc, DW_FORM_addrx, },
{ DW_AT_high_pc, DW_FORM_data4, },
{ DW_AT_frame_base, DW_FORM_exprloc, },
{ DW_AT_call_all_calls, DW_FORM_flag_present, },
{ DW_AT_name, DW_FORM_strx1, },
{ DW_AT_decl_file, DW_FORM_data1, },
{ DW_AT_decl_line, DW_FORM_data1, },
{ DW_AT_type, DW_FORM_ref4, },
{ DW_AT_external, DW_FORM_flag_present, },
};
encode_attribute_abbreviations(builder, (Slice(DwarfAttributeFormPair)) array_to_slice(subprogram));
// Abbreviation entry
uleb128_encode(&builder->file, 3);
// Abbreviation kind
uleb128_encode(&builder->file, DW_TAG_base_type);
// Has children
*vb_add(&builder->file, 1) = 0; // has children
memcpy(vb_add(&builder->file, size), data, size);
DwarfAttributeFormPair base_type[] = {
{ DW_AT_name, DW_FORM_strx1, },
{ DW_AT_encoding, DW_FORM_data1, },
{ DW_AT_byte_size, DW_FORM_data1, },
};
encode_attribute_abbreviations(builder, (Slice(DwarfAttributeFormPair)) array_to_slice(base_type));
// End with a null entry
*vb_add(&builder->file, 1) = 0;
auto size = builder->file.length - offset;
*section_header = (ELFSectionHeader) {
.name_offset = name,