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lld+macho: lld xcomp to x86_64 macos now works

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This commit is contained in:
Jakub Konka 2020-12-05 12:59:28 +01:00
parent eb528a9cbc
commit 2e7883c597
2 changed files with 106 additions and 1 deletions
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27
lib/std/macho.zig
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@ -1257,6 +1257,33 @@ pub const VM_PROT_WRITE: vm_prot_t = 0x2;
/// VM execute permission
pub const VM_PROT_EXECUTE: vm_prot_t = 0x4;
pub const BIND_TYPE_POINTER: u8 = 1;
pub const BIND_TYPE_TEXT_ABSOLUTE32: u8 = 2;
pub const BIND_TYPE_TEXT_PCREL32: u8 = 3;
pub const BIND_SPECIAL_DYLIB_SELF: i8 = 0;
pub const BIND_SPECIAL_DYLIB_MAIN_EXECUTABLE: i8 = -1;
pub const BIND_SPECIAL_DYLIB_FLAT_LOOKUP: i8 = -2;
pub const BIND_SYMBOL_FLAGS_WEAK_IMPORT: u8 = 0x1;
pub const BIND_SYMBOL_FLAGS_NON_WEAK_DEFINITION: u8 = 0x8;
pub const BIND_OPCODE_MASK: u8 = 0xf0;
pub const BIND_IMMEDIATE_MASK: u8 = 0x0f;
pub const BIND_OPCODE_DONE: u8 = 0x00;
pub const BIND_OPCODE_SET_DYLIB_ORDINAL_IMM: u8 = 0x10;
pub const BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB: u8 = 0x20;
pub const BIND_OPCODE_SET_DYLIB_SPECIAL_IMM: u8 = 0x30;
pub const BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM: u8 = 0x40;
pub const BIND_OPCODE_SET_TYPE_IMM: u8 = 0x50;
pub const BIND_OPCODE_SET_ADDEND_SLEB: u8 = 0x60;
pub const BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB: u8 = 0x70;
pub const BIND_OPCODE_ADD_ADDR_ULEB: 0x80;
pub const BIND_OPCODE_DO_BIND: u8 = 0x90;
pub const BIND_OPCODE_DO_BIND_ADD_ADDR_ULEB: u8 = 0xa0;
pub const BIND_OPCODE_DO_BIND_ADD_ADDR_IMM_SCALED: u8 = 0xb0;
pub const BIND_OPCODE_DO_BIND_ULEB_TIMES_SKIPPING_ULEB: u8 = xc0;
pub const reloc_type_x86_64 = packed enum(u4) {
/// for absolute addresses
X86_64_RELOC_UNSIGNED = 0,

80
src/link/MachO.zig
View File

@ -107,6 +107,7 @@ offset_table: std.ArrayListUnmanaged(u64) = .{},
error_flags: File.ErrorFlags = File.ErrorFlags{},
cmd_table_dirty: bool = false,
other_dylibs_present: bool = false,
/// A list of text blocks that have surplus capacity. This list can have false
/// positives, as functions grow and shrink over time, only sometimes being added
@ -755,6 +756,7 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
const out_file = try directory.handle.openFile(self.base.options.emit.?.sub_path, .{ .write = true });
try self.parseFromFile(out_file);
if (self.libsystem_cmd_index == null) {
if (self.other_dylibs_present) return; // TODO We cannot handle this situation yet.
const text_segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const text_section = text_segment.sections.items[self.text_section_index.?];
const after_last_cmd_offset = self.header.?.sizeofcmds + @sizeOf(macho.mach_header_64);
@ -787,7 +789,9 @@ fn linkWithLLD(self: *MachO, comp: *Compilation) !void {
mem.set(u8, dylib_cmd.data, 0);
mem.copy(u8, dylib_cmd.data, mem.spanZ(LIB_SYSTEM_PATH));
try self.load_commands.append(self.base.allocator, .{ .Dylib = dylib_cmd });
// TODO Fixup linkedit data
// Parse dyld info
try self.parseBindingInfo();
try self.parseLazyBindingInfo();
// Write updated load commands and the header
try self.writeLoadCommands();
try self.writeHeader();
@ -2002,6 +2006,8 @@ fn parseFromFile(self: *MachO, file: fs.File) !void {
const x = cmd.Dylib;
if (parseAndCmpName(x.data, mem.spanZ(LIB_SYSTEM_PATH))) {
self.libsystem_cmd_index = i;
} else {
self.other_dylibs_present = true;
}
},
macho.LC_FUNCTION_STARTS => {
@ -2030,3 +2036,75 @@ fn parseAndCmpName(name: []const u8, needle: []const u8) bool {
const len = mem.indexOfScalar(u8, name[0..], @as(u8, 0)) orelse name.len;
return mem.eql(u8, name[0..len], needle);
}
fn parseBindingInfo(self: *MachO) !void {
const dyld_info = self.load_commands.items[self.dyld_info_cmd_index.?].DyldInfoOnly;
var buffer = try self.base.allocator.alloc(u8, dyld_info.bind_size);
defer self.base.allocator.free(buffer);
const nread = try self.base.file.?.preadAll(buffer, dyld_info.bind_off);
assert(nread == buffer.len);
if (try parseAndFixupBindingInfoBuffer(self.base.allocator, buffer)) {
try self.base.file.?.pwriteAll(buffer, dyld_info.bind_off);
}
}
fn parseLazyBindingInfo(self: *MachO) !void {
const dyld_info = self.load_commands.items[self.dyld_info_cmd_index.?].DyldInfoOnly;
var buffer = try self.base.allocator.alloc(u8, dyld_info.lazy_bind_size);
defer self.base.allocator.free(buffer);
const nread = try self.base.file.?.preadAll(buffer, dyld_info.lazy_bind_off);
assert(nread == buffer.len);
if (try parseAndFixupBindingInfoBuffer(self.base.allocator, buffer)) {
try self.base.file.?.pwriteAll(buffer, dyld_info.lazy_bind_off);
}
}
fn parseAndFixupBindingInfoBuffer(allocator: *Allocator, buffer: []u8) !bool{
var stream = std.io.fixedBufferStream(buffer);
var reader = stream.reader();
var done = false;
var fixups = std.ArrayList(usize).init(allocator);
defer fixups.deinit();
while (true) {
const inst = reader.readByte() catch |err| switch (err) {
error.EndOfStream => break,
else => return err,
};
const imm: u8 = inst & macho.BIND_IMMEDIATE_MASK;
const opcode: u8 = inst & macho.BIND_OPCODE_MASK;
switch (opcode) {
macho.BIND_OPCODE_DONE => {
done = true; // TODO There appear to be multiple BIND_OPCODE_DONE in lazy binding info...
},
macho.BIND_OPCODE_SET_SYMBOL_TRAILING_FLAGS_IMM => {
var next = try reader.readByte();
while (next != @as(u8, 0)) {
next = try reader.readByte();
}
},
macho.BIND_OPCODE_SET_SEGMENT_AND_OFFSET_ULEB => {
const uleb_enc = try std.leb.readULEB128(u64, reader);
},
macho.BIND_OPCODE_SET_DYLIB_SPECIAL_IMM => {
// We note the position in the stream to fixup later.
const pos = try reader.context.getPos();
try fixups.append(pos - 1);
},
else => {},
}
}
assert(done);
var buffer_dirty = false;
try stream.seekTo(0);
var writer = stream.writer();
for (fixups.items) |pos| {
try writer.context.seekTo(pos);
const inst = macho.BIND_OPCODE_SET_DYLIB_ORDINAL_IMM | 1;
_ = try writer.write(&[_]u8{inst});
buffer_dirty = true;
}
return buffer_dirty;
}