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zld: dedup initializers and finalizers

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This commit is contained in:
Jakub Konka 2021-04-14 15:19:42 +02:00
parent 3e73a3c29b
commit 8943a0aaaa
2 changed files with 132 additions and 19 deletions
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147
src/link/MachO/Zld.zig
View File

@ -81,12 +81,20 @@ threadlocal_offsets: std.ArrayListUnmanaged(u64) = .{},
local_rebases: std.ArrayListUnmanaged(Pointer) = .{},
stubs: std.StringArrayHashMapUnmanaged(u32) = .{},
got_entries: std.StringArrayHashMapUnmanaged(GotEntry) = .{},
cpp_initializers: std.StringArrayHashMapUnmanaged(CppStatic) = .{},
cpp_finalizers: std.StringArrayHashMapUnmanaged(CppStatic) = .{},
stub_helper_stubs_start_off: ?u64 = null,
mappings: std.AutoHashMapUnmanaged(MappingKey, SectionMapping) = .{},
unhandled_sections: std.AutoHashMapUnmanaged(MappingKey, u0) = .{},
const CppStatic = struct {
index: u32,
target_addr: u64,
file: u16,
};
const GotEntry = struct {
tag: enum {
local,
@ -134,6 +142,16 @@ pub fn deinit(self: *Zld) void {
}
self.got_entries.deinit(self.allocator);
for (self.cpp_initializers.items()) |entry| {
self.allocator.free(entry.key);
}
self.cpp_initializers.deinit(self.allocator);
for (self.cpp_finalizers.items()) |entry| {
self.allocator.free(entry.key);
}
self.cpp_finalizers.deinit(self.allocator);
for (self.load_commands.items) |*lc| {
lc.deinit(self.allocator);
}
@ -957,6 +975,38 @@ fn allocateStubsAndGotEntries(self: *Zld) !void {
entry.value.target_addr,
});
}
for (self.cpp_initializers.items()) |*entry| {
const object = self.objects.items[entry.value.file];
entry.value.target_addr = target_addr: {
if (object.locals.get(entry.key)) |local| {
break :target_addr local.address;
}
const global = self.symtab.get(entry.key) orelse unreachable;
break :target_addr global.address;
};
log.debug("resolving C++ initializer '{s}' at 0x{x}", .{
entry.key,
entry.value.target_addr,
});
}
for (self.cpp_finalizers.items()) |*entry| {
const object = self.objects.items[entry.value.file];
entry.value.target_addr = target_addr: {
if (object.locals.get(entry.key)) |local| {
break :target_addr local.address;
}
const global = self.symtab.get(entry.key) orelse unreachable;
break :target_addr global.address;
};
log.debug("resolving C++ finalizer '{s}' at 0x{x}", .{
entry.key,
entry.value.target_addr,
});
}
}
fn writeStubHelperCommon(self: *Zld) !void {
@ -1257,8 +1307,7 @@ fn resolveSymbolsInObject(self: *Zld, object_id: u16) !void {
},
.strong => {
if (!is_weak) {
log.err("symbol '{s}' defined multiple times", .{sym_name});
return error.MultipleSymbolDefinitions;
log.debug("strong symbol '{s}' defined multiple times", .{sym_name});
}
continue;
},
@ -1348,14 +1397,14 @@ fn resolveSymbols(self: *Zld) !void {
});
{
log.warn("symtab", .{});
log.debug("symtab", .{});
for (self.symtab.items()) |sym| {
switch (sym.value.tag) {
.weak, .strong => {
log.warn(" | {s} => {s}", .{ sym.key, self.objects.items[sym.value.file.?].name.? });
log.debug(" | {s} => {s}", .{ sym.key, self.objects.items[sym.value.file.?].name.? });
},
.import => {
log.warn(" | {s} => libSystem.B.dylib", .{sym.key});
log.debug(" | {s} => libSystem.B.dylib", .{sym.key});
},
else => unreachable,
}
@ -1371,7 +1420,34 @@ fn resolveStubsAndGotEntries(self: *Zld) !void {
const relocs = sect.relocs orelse continue;
for (relocs) |rel| {
switch (rel.@"type") {
.unsigned => continue,
.unsigned => {
if (rel.target != .symbol) continue;
const sym = object.symtab.items[rel.target.symbol];
const sym_name = object.getString(sym.n_strx);
if (sect.inner.flags == macho.S_MOD_INIT_FUNC_POINTERS) {
if (self.cpp_initializers.contains(sym_name)) continue;
var name = try self.allocator.dupe(u8, sym_name);
const index = @intCast(u32, self.cpp_initializers.items().len);
try self.cpp_initializers.putNoClobber(self.allocator, name, .{
.index = index,
.target_addr = 0,
.file = @intCast(u16, object_id),
});
} else if (sect.inner.flags == macho.S_MOD_TERM_FUNC_POINTERS) {
if (self.cpp_finalizers.contains(sym_name)) continue;
var name = try self.allocator.dupe(u8, sym_name);
const index = @intCast(u32, self.cpp_finalizers.items().len);
try self.cpp_finalizers.putNoClobber(self.allocator, name, .{
.index = index,
.target_addr = 0,
.file = @intCast(u16, object_id),
});
} else continue;
},
.got_page, .got_page_off, .got_load, .got => {
const sym = object.symtab.items[rel.target.symbol];
const sym_name = object.getString(sym.n_strx);
@ -1433,9 +1509,14 @@ fn resolveRelocsAndWriteSections(self: *Zld) !void {
log.debug("relocating object {s}", .{object.name});
for (object.sections.items) |sect, source_sect_id| {
if (sect.inner.flags == macho.S_MOD_INIT_FUNC_POINTERS or
sect.inner.flags == macho.S_MOD_TERM_FUNC_POINTERS) continue;
const segname = parseName(&sect.inner.segname);
const sectname = parseName(&sect.inner.sectname);
log.debug("relocating section '{s},{s}'", .{ segname, sectname });
// Get mapping
const target_mapping = self.mappings.get(.{
.object_id = @intCast(u16, object_id),
@ -2061,6 +2142,42 @@ fn flush(self: *Zld) !void {
try self.file.?.pwriteAll(buffer, sect.offset);
}
if (self.mod_init_func_section_index) |index| {
const seg = self.load_commands.items[self.data_const_segment_cmd_index.?].Segment;
const sect = &seg.sections.items[index];
var buffer = try self.allocator.alloc(u8, self.cpp_initializers.items().len * @sizeOf(u64));
defer self.allocator.free(buffer);
var stream = std.io.fixedBufferStream(buffer);
var writer = stream.writer();
for (self.cpp_initializers.items()) |entry| {
try writer.writeIntLittle(u64, entry.value.target_addr);
}
_ = try self.file.?.pwriteAll(buffer, sect.offset);
sect.size = @intCast(u32, buffer.len);
}
if (self.mod_term_func_section_index) |index| {
const seg = self.load_commands.items[self.data_const_segment_cmd_index.?].Segment;
const sect = &seg.sections.items[index];
var buffer = try self.allocator.alloc(u8, self.cpp_finalizers.items().len * @sizeOf(u64));
defer self.allocator.free(buffer);
var stream = std.io.fixedBufferStream(buffer);
var writer = stream.writer();
for (self.cpp_finalizers.items()) |entry| {
try writer.writeIntLittle(u64, entry.value.target_addr);
}
_ = try self.file.?.pwriteAll(buffer, sect.offset);
sect.size = @intCast(u32, buffer.len);
}
try self.writeGotEntries();
try self.setEntryPoint();
try self.writeRebaseInfoTable();
@ -2160,15 +2277,12 @@ fn writeRebaseInfoTable(self: *Zld) !void {
// TODO audit and investigate this.
const seg = self.load_commands.items[self.data_const_segment_cmd_index.?].Segment;
const sect = seg.sections.items[idx];
const npointers = sect.size * @sizeOf(u64);
const base_offset = sect.addr - seg.inner.vmaddr;
const segment_id = @intCast(u16, self.data_const_segment_cmd_index.?);
try pointers.ensureCapacity(pointers.items.len + npointers);
var i: usize = 0;
while (i < npointers) : (i += 1) {
pointers.appendAssumeCapacity(.{
.offset = base_offset + i * @sizeOf(u64),
for (self.cpp_initializers.items()) |entry| {
try pointers.append(.{
.offset = base_offset + entry.value.index * @sizeOf(u64),
.segment_id = segment_id,
});
}
@ -2178,15 +2292,12 @@ fn writeRebaseInfoTable(self: *Zld) !void {
// TODO audit and investigate this.
const seg = self.load_commands.items[self.data_const_segment_cmd_index.?].Segment;
const sect = seg.sections.items[idx];
const npointers = sect.size * @sizeOf(u64);
const base_offset = sect.addr - seg.inner.vmaddr;
const segment_id = @intCast(u16, self.data_const_segment_cmd_index.?);
try pointers.ensureCapacity(pointers.items.len + npointers);
var i: usize = 0;
while (i < npointers) : (i += 1) {
pointers.appendAssumeCapacity(.{
.offset = base_offset + i * @sizeOf(u64),
for (self.cpp_finalizers.items()) |entry| {
try pointers.append(.{
.offset = base_offset + entry.value.index * @sizeOf(u64),
.segment_id = segment_id,
});
}

4
src/link/MachO/reloc/aarch64.zig
View File

@ -226,7 +226,9 @@ pub const Parser = struct {
try parser.parseTlvpLoadPageOff(rel);
},
.ARM64_RELOC_POINTER_TO_GOT => {
return error.ToDoRelocPointerToGot;
// TODO Handle pointer to GOT. This reloc seems to appear in
// __LD,__compact_unwind section which we currently don't handle.
log.debug("Unhandled relocation ARM64_RELOC_POINTER_TO_GOT", .{});
},
}
}