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Some deciphering on .eh_frame

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David Gonzalez Martin 2024-09-20 19:55:04 -06:00 committed by David
parent c495859ba9
commit a662dde651
1 changed files with 106 additions and 15 deletions
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121
bootstrap/main.c
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@ -1289,6 +1289,40 @@ typedef enum DwarfOperation : u8
DW_OP_hi_user = 0xff,
} DwarfOperation;
typedef enum DwarfCallFrame : u8
{
// High 2 Low 6
// Instruction Bits Bits Operand 1 Operand 2
// DW_CFA_advance_loc 0x1 delta
// DW_CFA_offset 0x2 register ULEB128 offset
// DW_CFA_restore 0x3 register
DW_CFA_nop = 0x00,
DW_CFA_set_loc = 0x01, // address
DW_CFA_advance_loc1 = 0x02, // 1-byte delta
DW_CFA_advance_loc2 = 0x03, // 2-byte delta
DW_CFA_advance_loc4 = 0x04, // 4-byte delta
DW_CFA_offset_extended = 0x05, // ULEB128 register ULEB128 offset
DW_CFA_restore_extended = 0x06, // ULEB128 register
DW_CFA_undefined = 0x07, // ULEB128 register
DW_CFA_same_value = 0x08, // ULEB128 register
DW_CFA_register = 0x09, // ULEB128 register ULEB128 offset
DW_CFA_remember_state = 0x0a,
DW_CFA_restore_state = 0x0b,
DW_CFA_def_cfa = 0x0c, // ULEB128 register ULEB128 offset
DW_CFA_def_cfa_register = 0x0d, // ULEB128 register
DW_CFA_def_cfa_offset = 0x0e, // ULEB128 offset
DW_CFA_def_cfa_expression = 0x0f, // BLOCK
DW_CFA_expression = 0x10, // ULEB128 register BLOCK
DW_CFA_offset_extended_sf = 0x11, // ULEB128 register SLEB128 offset
DW_CFA_def_cfa_sf = 0x12, // ULEB128 register SLEB128 offset
DW_CFA_def_cfa_offset_sf = 0x13, // SLEB128 offset
DW_CFA_val_offset = 0x14, // ULEB128 ULEB128
DW_CFA_val_offset_sf = 0x15, // ULEB128 SLEB128
DW_CFA_val_expression = 0x16, // ULEB128 BLOCK
DW_CFA_lo_user = 0x1c,
DW_CFA_hi_user
} DwarfCallFrame;
String dwarf_operation_to_string(DwarfOperation operation)
{
switch (operation)
@ -8782,6 +8816,7 @@ may_be_unused fn void write_elf(Thread* thread, const ObjectOptions* const restr
auto name = elf_get_section_name(builder, strlit(".eh_frame"));
// Start of CIE
u32 length = 0x14;
*(u32*)vb_add(&builder->file, sizeof(u32)) = length;
u32 id = 0;
@ -8791,27 +8826,85 @@ may_be_unused fn void write_elf(Thread* thread, const ObjectOptions* const restr
auto augmentation = strlit("zR");
memcpy(vb_add(&builder->file, augmentation.length + 1), augmentation.pointer, augmentation.length + 1);
u32 code_alignment_factor = 1;
s32 data_alignment_factor = -8;
u32 return_address_coumn = 0x10;
u32 code_alignment_factor = 1;
uleb128_encode(&builder->file, code_alignment_factor);
s32 data_alignment_factor = -8;
sleb128_encode(&builder->file, data_alignment_factor);
u32 return_address_coumn = 0x10;
uleb128_encode(&builder->file, return_address_coumn);
// TODO: figure out what this is
*vb_add(&builder->file, 1) = 0x01;
*vb_add(&builder->file, 1) = 0x1b;
*vb_add(&builder->file, 1) = 0x01; // TODO: figure out what this is
// TODO: figure out this bunch of dwarf stuff
u8 data[] = {
0x0C, 0x07, 0x08, 0x90, 0x01, 0x00, 0x00, 0x14, 0x00, 0x00, 0x00, 0x1C, 0x00, 0x00, 0x00,
0xE0, 0xEF, 0xFF, 0xFF, 0x26, 0x00, 0x00, 0x00, 0x00, 0x44, 0x07, 0x10, 0x00, 0x00, 0x00, 0x00,
0x10, 0x00, 0x00, 0x00, 0x34, 0x00, 0x00, 0x00, 0xC4, 0xF0, 0xFF, 0xFF, 0x03, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
u8 augmentation_data = 0x1b;
*vb_add(&builder->file, 1) = augmentation_data;
{
*vb_add(&builder->file, 1) = DW_CFA_def_cfa;
*vb_add(&builder->file, 1) = 7; // RSP
*vb_add(&builder->file, 1) = 8;
// figure out DW_CFA_offset: RIP -8
*vb_add(&builder->file, 1) = (0x02 << 6) | 0x10; // -8 in 6-bit => 0b010000 ??
*vb_add(&builder->file, 1) = 0x01;
*vb_add(&builder->file, 1) = DW_CFA_nop;
*vb_add(&builder->file, 1) = DW_CFA_nop;
}
// End of CIE
STRUCT(FrameDescriptorEntryHeader)
{
u32 length;
u32 pointer;
};
memcpy(vb_add(&builder->file, sizeof(data)), data, sizeof(data));
// Start of FDE
{
*vb_add_struct(&builder->file, FrameDescriptorEntryHeader) = (FrameDescriptorEntryHeader) {
.length = 0x14,
.pointer = 0x1c,
};
// Relocated
s32 initial_location = 0xffffefe0;
assert(initial_location == -4128);
*(s32*)(vb_add(&builder->file, sizeof(s32))) = initial_location;
u32 size = 0x26;
*(u32*)(vb_add(&builder->file, sizeof(u32))) = size;
*vb_add(&builder->file, 1) = 0; // TODO: ???
*vb_add(&builder->file, 1) = (0x01 << 6) | 0x04; // DW_CFA_advance_loc (4)
*vb_add(&builder->file, 1) = DW_CFA_undefined;
*vb_add(&builder->file, 1) = 0x10; // RIP
*(u32*)vb_add(&builder->file, sizeof(u32)) = 0;
// End of FDE
}
// Start of FDE
{
*vb_add_struct(&builder->file, FrameDescriptorEntryHeader) = (FrameDescriptorEntryHeader) {
.length = 0x10,
.pointer = 0x34,
};
s32 initial_location = 0xfffff0c4;
*(s32*)(vb_add(&builder->file, sizeof(s32))) = initial_location;
u32 size = 3;
*(u32*)(vb_add(&builder->file, sizeof(u32))) = size;
*(u32*)(vb_add(&builder->file, sizeof(u32))) = 0; // TODO: ???
*(u32*)(vb_add(&builder->file, sizeof(u32))) = 0; // TODO: ???
// End of FDE
}
auto size = builder->file.length - offset;
@ -13579,8 +13672,6 @@ fn void print_ir(Thread* restrict thread)
}
}
fn void entry_point(int argc, char* argv[], char* envp[])
{
#if DO_UNIT_TESTS