Commit 0a0f90f949942b19950455647bc955b369407dd4 | zig

author	Jakub Konka <kubkon@jakubkonka.com> 2024-02-03 10:52:29+01:00
committer	Jakub Konka <kubkon@jakubkonka.com> 2024-02-03 10:52:29+01:00
log	0a0f90f949942b19950455647bc955b369407dd4
tree	44debca2e688edfcee5db118bbc4c5967dd304f3
parent	aa1aa9886333e8b260901572142a227e5544f4df

macho: migrate thunks to use new relative addressing mechanism

4 files changed, 11 insertions(+), 16 deletions(-)

src
- link
  - MachO.zig
  - MachO
    Atom.zig
    relocatable.zig
    thunks.zig

src/link/MachO.zig+1-10

...	...	@@ -596,7 +596,6 @@ pub fn flushModule(self: MachO, arena: Allocator, prog_node: std.Progress.Node
596	596
597	597	try self.allocateSections();
598	598	self.allocateSegments();
599		self.allocateAtoms();
600	599	self.allocateSyntheticSymbols();
601	600	try self.allocateLinkeditSegment();
602	601
...	...	@@ -2392,14 +2391,6 @@ fn allocateSegments(self: *MachO) void {
2392	2391	}
2393	2392	}
2394	2393
2395		pub fn allocateAtoms(self: *MachO) void {
2396		// TODO: redo this like atoms
2397		for (self.thunks.items) \|*thunk\| {
2398		const header = self.sections.items(.header)[thunk.out_n_sect];
2399		thunk.value += header.addr;
2400		}
2401		}
2402
2403	2394	fn allocateSyntheticSymbols(self: *MachO) void {
2404	2395	const text_seg = self.getTextSegment();
2405	2396
...	...	@@ -2608,7 +2599,7 @@ fn writeAtoms(self: *MachO) !void {
2608	2599
2609	2600	for (self.thunks.items) \|thunk\| {
2610	2601	const header = slice.items(.header)[thunk.out_n_sect];
2611		const offset = thunk.value - header.addr + header.offset;
	2602	const offset = thunk.value + header.offset;
2612	2603	const buffer = try gpa.alloc(u8, thunk.size());
2613	2604	defer gpa.free(buffer);
2614	2605	var stream = std.io.fixedBufferStream(buffer);

src/link/MachO/Atom.zig+1-1

...	...	@@ -706,7 +706,7 @@ fn resolveRelocInner(
706	706	.aarch64 => {
707	707	const disp: i28 = math.cast(i28, S + A - P) orelse blk: {
708	708	const thunk = self.getThunk(macho_file);
709		const S_: i64 = @intCast(thunk.getAddress(rel.target));
	709	const S_: i64 = @intCast(thunk.getTargetAddress(rel.target, macho_file));
710	710	break :blk math.cast(i28, S_ + A - P) orelse return error.Overflow;
711	711	};
712	712	var inst = aarch64.Instruction{

src/link/MachO/relocatable.zig-1

...	...	@@ -61,7 +61,6 @@ pub fn flush(macho_file: MachO, comp: Compilation, module_obj_path: ?[]const u
61	61	try createSegment(macho_file);
62	62	try allocateSections(macho_file);
63	63	allocateSegment(macho_file);
64		macho_file.allocateAtoms();
65	64
66	65	var off = off: {
67	66	const seg = macho_file.segments.items[0];

src/link/MachO/thunks.zig+9-4

...	...	@@ -66,7 +66,7 @@ fn isReachable(atom: const Atom, rel: Relocation, macho_file: MachO) bool {
66	66	if (atom.out_n_sect != target.out_n_sect) return false;
67	67	const target_atom = target.getAtom(macho_file).?;
68	68	if (target_atom.value == @as(u64, @bitCast(@as(i64, -1)))) return false;
69		const saddr = @as(i64, @intCast(atom.value)) + @as(i64, @intCast(rel.offset - atom.off));
	69	const saddr = @as(i64, @intCast(atom.getAddress(macho_file))) + @as(i64, @intCast(rel.offset - atom.off));
70	70	const taddr: i64 = @intCast(rel.getTargetAddress(macho_file));
71	71	_ = math.cast(i28, taddr + rel.addend - saddr) orelse return false;
72	72	return true;
...	...	@@ -85,14 +85,19 @@ pub const Thunk = struct {
85	85	return thunk.symbols.keys().len * trampoline_size;
86	86	}
87	87
88		pub fn getAddress(thunk: Thunk, sym_index: Symbol.Index) u64 {
89		return thunk.value + thunk.symbols.getIndex(sym_index).? * trampoline_size;
	88	pub fn getAddress(thunk: Thunk, macho_file: *MachO) u64 {
	89	const header = macho_file.sections.items(.header)[thunk.out_n_sect];
	90	return header.addr + thunk.value;
	91	}
	92
	93	pub fn getTargetAddress(thunk: Thunk, sym_index: Symbol.Index, macho_file: *MachO) u64 {
	94	return thunk.getAddress(macho_file) + thunk.symbols.getIndex(sym_index).? * trampoline_size;
90	95	}
91	96
92	97	pub fn write(thunk: Thunk, macho_file: *MachO, writer: anytype) !void {
93	98	for (thunk.symbols.keys(), 0..) \|sym_index, i\| {
94	99	const sym = macho_file.getSymbol(sym_index);
95		const saddr = thunk.value + i * trampoline_size;
	100	const saddr = thunk.getAddress(macho_file) + i * trampoline_size;
96	101	const taddr = sym.getAddress(.{}, macho_file);
97	102	const pages = try Relocation.calcNumberOfPages(saddr, taddr);
98	103	try writer.writeInt(u32, aarch64.Instruction.adrp(.x16, pages).toU32(), .little);