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macho: fully working PoC with main and exit

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This commit is contained in:
Jakub Konka 2021-01-07 20:49:07 +01:00
parent bb691ea16b
commit 2f7cd71193
2 changed files with 49 additions and 24 deletions
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66
src/link/MachO.zig
View File

@ -1263,9 +1263,10 @@ pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
const stub_h = &text_segment.sections.items[self.stub_helper_section_index.?];
const data_segment = &self.load_commands.items[self.data_segment_cmd_index.?].Segment;
const la_ptr = &data_segment.sections.items[self.la_symbol_ptr_section_index.?];
while (self.stub_fixups.popOrNull()) |fixup| {
for (self.stub_fixups.items) |fixup, idx| {
const i = @intCast(u32, idx);
// TODO increment offset for stub writing
const stub_addr = stubs.addr;
const stub_addr = stubs.addr + i * stubs.reserved2;
const text_addr = symbol.n_value + fixup.start;
const displacement = @intCast(u32, stub_addr - text_addr);
var placeholder = code_buffer.items[fixup.start..][0..fixup.len];
@ -1274,17 +1275,16 @@ pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
const end = stub_h.addr + self.next_stub_helper_off.? - stub_h.offset;
var buf: [@sizeOf(u64)]u8 = undefined;
mem.writeIntLittle(u64, &buf, end);
try self.base.file.?.pwriteAll(&buf, la_ptr.offset);
try self.base.file.?.pwriteAll(&buf, la_ptr.offset + i * @sizeOf(u64));
const displacement2 = la_ptr.addr - stubs.addr;
const la_ptr_addr = la_ptr.addr + i * @sizeOf(u64);
const displacement2 = la_ptr_addr - stub_addr;
var ccode: [2 * @sizeOf(u32)]u8 = undefined;
mem.writeIntLittle(u32, ccode[0..4], aarch64.Instruction.ldr(.x16, .{
.literal = @intCast(u19, displacement2 / 4),
}).toU32());
mem.writeIntLittle(u32, ccode[4..8], aarch64.Instruction.br(.x16).toU32());
try self.base.file.?.pwriteAll(&ccode, stubs.offset);
stubs.size = 2 * @sizeOf(u32);
stubs.reserved2 = 2 * @sizeOf(u32);
try self.base.file.?.pwriteAll(&ccode, stubs.offset + i * stubs.reserved2);
const displacement3 = @intCast(i64, stub_h.addr) - @intCast(i64, end + 4);
var cccode: [3 * @sizeOf(u32)]u8 = undefined;
@ -1292,13 +1292,13 @@ pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
.literal = 0x2,
}).toU32());
mem.writeIntLittle(u32, cccode[4..8], aarch64.Instruction.b(@intCast(i28, displacement3)).toU32());
mem.writeIntLittle(u32, cccode[8..12], 0);
mem.writeIntLittle(u32, cccode[8..12], i * 0xd);
try self.base.file.?.pwriteAll(&cccode, self.next_stub_helper_off.?);
self.next_stub_helper_off = self.next_stub_helper_off.? + 3 * @sizeOf(u32);
try self.rebase_info_table.symbols.append(self.base.allocator, .{
.segment = 3,
.offset = 0,
.offset = i * stubs.reserved2,
});
self.rebase_info_dirty = true;
@ -1308,12 +1308,13 @@ pub fn updateDecl(self: *MachO, module: *Module, decl: *Module.Decl) !void {
mem.copy(u8, name, name_str);
try self.lazy_binding_info_table.symbols.append(self.base.allocator, .{
.segment = 3,
.offset = 0,
.offset = i * @sizeOf(u64),
.dylib_ordinal = 1,
.name = name,
});
self.lazy_binding_info_dirty = true;
}
self.stub_fixups.shrinkRetainingCapacity(0);
const text_section = text_segment.sections.items[self.text_section_index.?];
const section_offset = symbol.n_value - text_section.addr;
@ -1634,7 +1635,7 @@ pub fn populateMissingMetadata(self: *MachO) !void {
.nreloc = 0,
.flags = flags,
.reserved1 = 0,
.reserved2 = 0,
.reserved2 = 2 * @sizeOf(u32),
.reserved3 = 0,
});
self.header_dirty = true;
@ -2539,20 +2540,45 @@ fn writeIndirectSymbolTable(self: *MachO) !void {
const la = &data_seg.sections.items[self.la_symbol_ptr_section_index.?];
const dysymtab = &self.load_commands.items[self.dysymtab_cmd_index.?].Dysymtab;
dysymtab.nindirectsyms = 0;
var buf: [@sizeOf(u32)]u8 = undefined;
var off = dysymtab.indirectsymoff;
var idx: u32 = 0;
stubs.reserved1 = 0;
for (self.undef_symbols.items) |sym, i| {
const idx = @intCast(u32, dysymtab.iundefsym + i);
var buf: [@sizeOf(u32)]u8 = undefined;
mem.writeIntLittle(u32, &buf, idx);
try self.base.file.?.pwriteAll(&buf, dysymtab.indirectsymoff + i * @sizeOf(u32));
dysymtab.nindirectsyms += 1;
if (i == self.dyld_stub_binder_index.?) {
got.reserved1 = @intCast(u32, i);
continue;
}
stubs.reserved1 = @intCast(u32, i);
try self.base.file.?.pwriteAll(&buf, dysymtab.indirectsymoff + (i + 1) * @sizeOf(u32));
la.reserved1 = @intCast(u32, i + 1);
const symtab_idx = @intCast(u32, dysymtab.iundefsym + i);
mem.writeIntLittle(u32, &buf, symtab_idx);
try self.base.file.?.pwriteAll(&buf, off);
off += @sizeOf(u32);
dysymtab.nindirectsyms += 1;
idx += 1;
}
got.reserved1 = @intCast(u32, self.undef_symbols.items.len - 1);
if (self.dyld_stub_binder_index) |i| {
const symtab_idx = i + dysymtab.iundefsym;
mem.writeIntLittle(u32, &buf, symtab_idx);
try self.base.file.?.pwriteAll(&buf, off);
off += @sizeOf(u32);
dysymtab.nindirectsyms += 1;
idx += 1;
}
la.reserved1 = got.reserved1 + 1;
for (self.undef_symbols.items) |sym, i| {
if (i == self.dyld_stub_binder_index.?) {
continue;
}
const symtab_idx = @intCast(u32, dysymtab.iundefsym + i);
mem.writeIntLittle(u32, &buf, symtab_idx);
try self.base.file.?.pwriteAll(&buf, off);
off += @sizeOf(u32);
dysymtab.nindirectsyms += 1;
idx += 1;
}
}

7
src/link/MachO/imports.zig
View File

@ -21,9 +21,8 @@ pub const RebaseInfoTable = struct {
/// Write the rebase info table to byte stream.
pub fn write(self: RebaseInfoTable, writer: anytype) !void {
try writer.writeByte(macho.REBASE_OPCODE_SET_TYPE_IMM | @truncate(u4, self.rebase_type));
for (self.symbols.items) |symbol| {
try writer.writeByte(macho.REBASE_OPCODE_SET_TYPE_IMM | @truncate(u4, self.rebase_type));
try writer.writeByte(macho.REBASE_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB | @truncate(u4, symbol.segment));
try leb.writeILEB128(writer, symbol.offset);
try writer.writeByte(macho.REBASE_OPCODE_DO_REBASE_IMM_TIMES | @truncate(u4, 1));
@ -36,10 +35,10 @@ pub const RebaseInfoTable = struct {
pub fn calcSize(self: *RebaseInfoTable) !u64 {
var stream = std.io.countingWriter(std.io.null_writer);
var writer = stream.writer();
var size: u64 = 1;
var size: u64 = 0;
for (self.symbols.items) |symbol| {
size += 1;
size += 2;
try leb.writeILEB128(writer, symbol.offset);
size += 1;
}