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zld: sort tlv offsets by source address
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@kubkon
kubkon committed May 6, 2021
1 parent ef8a666 commit 88d40fc
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Showing 3 changed files with 28 additions and 23 deletions.
9 changes: 6 additions & 3 deletions src/link/MachO/Archive.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ allocator: *Allocator,
arch: ?std.Target.Cpu.Arch = null,
file: ?fs.File = null,
header: ?ar_hdr = null,
name: ?[]u8 = null,
name: ?[]const u8 = null,

/// Parsed table of contents.
/// Each symbol name points to a list of all definition
Expand Down Expand Up @@ -195,7 +195,7 @@ fn parseTableOfContents(self: *Archive, reader: anytype) !void {
}

/// Caller owns the Object instance.
pub fn parseObject(self: Archive, offset: u32) !Object {
pub fn parseObject(self: Archive, offset: u32) !*Object {
var reader = self.file.?.reader();
try reader.context.seekTo(offset);

Expand All @@ -217,7 +217,10 @@ pub fn parseObject(self: Archive, offset: u32) !Object {
break :name try std.fmt.allocPrint(self.allocator, "{s}({s})", .{ path, object_name });
};

var object = Object.init(self.allocator);
var object = try self.allocator.create(Object);
errdefer self.allocator.destroy(object);

object.* = Object.init(self.allocator);
object.arch = self.arch.?;
object.file = try fs.cwd().openFile(self.name.?, .{});
object.name = name;
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2 changes: 1 addition & 1 deletion src/link/MachO/Object.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ arch: ?std.Target.Cpu.Arch = null,
header: ?macho.mach_header_64 = null,
file: ?fs.File = null,
file_offset: ?u32 = null,
name: ?[]u8 = null,
name: ?[]const u8 = null,

load_commands: std.ArrayListUnmanaged(LoadCommand) = .{},
sections: std.ArrayListUnmanaged(Section) = .{},
Expand Down
40 changes: 21 additions & 19 deletions src/link/MachO/Zld.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -82,7 +82,7 @@ unresolved: std.StringArrayHashMapUnmanaged(*Symbol) = .{},
strtab: std.ArrayListUnmanaged(u8) = .{},
strtab_dir: std.StringHashMapUnmanaged(u32) = .{},

threadlocal_offsets: std.ArrayListUnmanaged(u64) = .{},
threadlocal_offsets: std.ArrayListUnmanaged(TlvOffset) = .{}, // TODO merge with Symbol abstraction
local_rebases: std.ArrayListUnmanaged(Pointer) = .{},
stubs: std.ArrayListUnmanaged(*Symbol) = .{},
got_entries: std.ArrayListUnmanaged(*Symbol) = .{},
Expand All @@ -92,6 +92,15 @@ stub_helper_stubs_start_off: ?u64 = null,
mappings: std.AutoHashMapUnmanaged(MappingKey, SectionMapping) = .{},
unhandled_sections: std.AutoHashMapUnmanaged(MappingKey, u0) = .{},

const TlvOffset = struct {
source_addr: u64,
offset: u64,

fn cmp(context: void, a: TlvOffset, b: TlvOffset) bool {
return a.source_addr < b.source_addr;
}
};

const MappingKey = struct {
object_id: u16,
source_sect_id: u16,
Expand Down Expand Up @@ -277,7 +286,7 @@ fn parseInputFiles(self: *Zld, files: []const []const u8) !void {

object.* = Object.init(self.allocator);
object.arch = self.arch.?;
object.name = try self.allocator.dupe(u8, input.name);
object.name = input.name;
object.file = input.file;
try object.parse();
try self.objects.append(self.allocator, object);
Expand All @@ -288,7 +297,7 @@ fn parseInputFiles(self: *Zld, files: []const []const u8) !void {

archive.* = Archive.init(self.allocator);
archive.arch = self.arch.?;
archive.name = try self.allocator.dupe(u8, input.name);
archive.name = input.name;
archive.file = input.file;
try archive.parse();
try self.archives.append(self.allocator, archive);
Expand Down Expand Up @@ -1362,10 +1371,7 @@ fn resolveSymbols(self: *Zld) !void {
};
assert(offsets.items.len > 0);

const object = try self.allocator.create(Object);
errdefer self.allocator.destroy(object);

object.* = try archive.parseObject(offsets.items[0]);
const object = try archive.parseObject(offsets.items[0]);
try self.objects.append(self.allocator, object);
try self.resolveSymbolsInObject(object);

Expand Down Expand Up @@ -1553,16 +1559,9 @@ fn resolveRelocsAndWriteSections(self: *Zld) !void {
// TLV is handled via a separate offset mechanism.
// Calculate the offset to the initializer.
if (target_sect.flags == macho.S_THREAD_LOCAL_VARIABLES) tlv: {
log.warn("HIT", .{});
log.warn(" | rel {any}", .{rel.cast(reloc.Unsigned).?});
log.warn(" | name {s}", .{rel.target.symbol.name});
log.warn(" | target address 0x{x}", .{args.target_addr});

// TODO we don't want to save offset to tlv_bootstrap
if (mem.eql(u8, rel.target.symbol.name, "__tlv_bootstrap")) break :tlv;

log.warn(" | object {s}", .{rel.target.symbol.cast(Symbol.Regular).?.file.name.?});

const base_addr = blk: {
if (self.tlv_data_section_index) |index| {
const tlv_data = target_seg.sections.items[index];
Expand All @@ -1572,11 +1571,12 @@ fn resolveRelocsAndWriteSections(self: *Zld) !void {
break :blk tlv_bss.addr;
}
};
log.warn(" | base address 0x{x}", .{base_addr});
log.warn(" | offset 0x{x}", .{args.target_addr - base_addr});
// Since we require TLV data to always preceed TLV bss section, we calculate
// offsets wrt to the former if it is defined; otherwise, wrt to the latter.
try self.threadlocal_offsets.append(self.allocator, args.target_addr - base_addr);
try self.threadlocal_offsets.append(self.allocator, .{
.source_addr = args.source_addr,
.offset = args.target_addr - base_addr,
});
}
},
.got_page, .got_page_off, .got_load, .got => {
Expand Down Expand Up @@ -2102,10 +2102,12 @@ fn flush(self: *Zld) !void {
var stream = std.io.fixedBufferStream(buffer);
var writer = stream.writer();

std.sort.sort(TlvOffset, self.threadlocal_offsets.items, {}, TlvOffset.cmp);

const seek_amt = 2 * @sizeOf(u64);
while (self.threadlocal_offsets.popOrNull()) |offset| {
for (self.threadlocal_offsets.items) |tlv| {
try writer.context.seekBy(seek_amt);
try writer.writeIntLittle(u64, offset);
try writer.writeIntLittle(u64, tlv.offset);
}

try self.file.?.pwriteAll(buffer, sect.offset);
Expand Down

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