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zld: port over a few more bits from ld64

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* UTF16 gets its own section, `__TEXT,__ustring`
* TLV data and bss sections have to aligned to the same max alignment
  according to Apple rdar comment in the latest ld64
This commit is contained in:
Jakub Konka 2021-05-04 10:59:33 +02:00
parent 1867c3c34c
commit 96556ce8b8
1 changed files with 96 additions and 23 deletions
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119
src/link/MachO/Zld.zig
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@ -58,6 +58,7 @@ stubs_section_index: ?u16 = null,
stub_helper_section_index: ?u16 = null,
text_const_section_index: ?u16 = null,
cstring_section_index: ?u16 = null,
ustring_section_index: ?u16 = null,
// __DATA_CONST segment sections
got_section_index: ?u16 = null,
@ -200,7 +201,6 @@ pub fn link(self: *Zld, files: []const []const u8, out_path: []const u8) !void {
try self.populateMetadata();
try self.parseInputFiles(files);
try self.resolveSymbols();
// self.printSymbols();
try self.resolveStubsAndGotEntries();
try self.updateMetadata();
try self.sortSections();
@ -209,8 +209,6 @@ pub fn link(self: *Zld, files: []const []const u8, out_path: []const u8) !void {
try self.allocateDataSegment();
self.allocateLinkeditSegment();
try self.allocateSymbols();
try self.writeStubHelperCommon();
try self.resolveRelocsAndWriteSections();
try self.flush();
}
@ -356,23 +354,43 @@ fn updateMetadata(self: *Zld) !void {
switch (flags) {
macho.S_REGULAR, macho.S_4BYTE_LITERALS, macho.S_8BYTE_LITERALS, macho.S_16BYTE_LITERALS => {
if (mem.eql(u8, segname, "__TEXT")) {
if (self.text_const_section_index != null) continue;
if (mem.eql(u8, sectname, "__ustring")) {
if (self.ustring_section_index != null) continue;
self.text_const_section_index = @intCast(u16, text_seg.sections.items.len);
try text_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__const"),
.segname = makeStaticString("__TEXT"),
.addr = 0,
.size = 0,
.offset = 0,
.@"align" = 0,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
self.ustring_section_index = @intCast(u16, text_seg.sections.items.len);
try text_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__ustring"),
.segname = makeStaticString("__TEXT"),
.addr = 0,
.size = 0,
.offset = 0,
.@"align" = 0,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
} else {
if (self.text_const_section_index != null) continue;
self.text_const_section_index = @intCast(u16, text_seg.sections.items.len);
try text_seg.addSection(self.allocator, .{
.sectname = makeStaticString("__const"),
.segname = makeStaticString("__TEXT"),
.addr = 0,
.size = 0,
.offset = 0,
.@"align" = 0,
.reloff = 0,
.nreloc = 0,
.flags = macho.S_REGULAR,
.reserved1 = 0,
.reserved2 = 0,
.reserved3 = 0,
});
}
} else if (mem.eql(u8, segname, "__DATA")) {
if (!mem.eql(u8, sectname, "__const")) continue;
if (self.data_const_section_index != null) continue;
@ -588,6 +606,50 @@ fn updateMetadata(self: *Zld) !void {
}, 0);
}
}
tlv_align: {
const has_tlv =
self.tlv_section_index != null or
self.tlv_data_section_index != null or
self.tlv_bss_section_index != null;
if (!has_tlv) break :tlv_align;
const seg = &self.load_commands.items[self.data_segment_cmd_index.?].Segment;
if (self.tlv_section_index) |index| {
const sect = &seg.sections.items[index];
sect.@"align" = 3; // __thread_vars is always 8byte aligned
}
// Apparently __tlv_data and __tlv_bss need to have matching alignment, so fix it up.
// <rdar://problem/24221680> All __thread_data and __thread_bss sections must have same alignment
// https://github.com/apple-opensource/ld64/blob/e28c028b20af187a16a7161d89e91868a450cadc/src/ld/ld.cpp#L1172
const data_align: u32 = data: {
if (self.tlv_data_section_index) |index| {
const sect = &seg.sections.items[index];
break :data sect.@"align";
}
break :tlv_align;
};
const bss_align: u32 = bss: {
if (self.tlv_bss_section_index) |index| {
const sect = &seg.sections.items[index];
break :bss sect.@"align";
}
break :tlv_align;
};
const max_align = math.max(data_align, bss_align);
if (self.tlv_data_section_index) |index| {
const sect = &seg.sections.items[index];
sect.@"align" = max_align;
}
if (self.tlv_bss_section_index) |index| {
const sect = &seg.sections.items[index];
sect.@"align" = max_align;
}
}
}
const MatchingSection = struct {
@ -663,10 +725,17 @@ fn getMatchingSection(self: *Zld, section: macho.section_64) ?MatchingSection {
},
macho.S_REGULAR => {
if (mem.eql(u8, segname, "__TEXT")) {
break :blk .{
.seg = self.text_segment_cmd_index.?,
.sect = self.text_const_section_index.?,
};
if (mem.eql(u8, sectname, "__ustring")) {
break :blk .{
.seg = self.text_segment_cmd_index.?,
.sect = self.ustring_section_index.?,
};
} else {
break :blk .{
.seg = self.text_segment_cmd_index.?,
.sect = self.text_const_section_index.?,
};
}
} else if (mem.eql(u8, segname, "__DATA")) {
if (mem.eql(u8, sectname, "__data")) {
break :blk .{
@ -712,6 +781,7 @@ fn sortSections(self: *Zld) !void {
&self.stub_helper_section_index,
&self.text_const_section_index,
&self.cstring_section_index,
&self.ustring_section_index,
};
for (indices) |maybe_index| {
const new_index: u16 = if (maybe_index.*) |index| blk: {
@ -1991,6 +2061,9 @@ fn populateMetadata(self: *Zld) !void {
}
fn flush(self: *Zld) !void {
try self.writeStubHelperCommon();
try self.resolveRelocsAndWriteSections();
if (self.common_section_index) |index| {
const seg = &self.load_commands.items[self.data_segment_cmd_index.?].Segment;
const sect = &seg.sections.items[index];