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macho: do not allocate atom for __stub_helper preamble
This commit is contained in:
Jakub Konka
parent
fa40267b04
commit
cec4755310
@ -152,7 +152,6 @@ globals_free_list: std.ArrayListUnmanaged(u32) = .{},
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dyld_stub_binder_index: ?u32 = null,
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dyld_private_atom_index: ?Atom.Index = null,
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stub_helper_preamble_atom_index: ?Atom.Index = null,
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strtab: StringTable(.strtab) = .{},
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@ -167,6 +166,7 @@ got_table_count_dirty: bool = false,
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got_table_contents_dirty: bool = false,
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stub_table_count_dirty: bool = false,
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stub_table_contents_dirty: bool = false,
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stub_helper_preamble_allocated: bool = false,
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/// A helper var to indicate if we are at the start of the incremental updates, or
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/// already somewhere further along the update-and-run chain.
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@ -723,15 +723,15 @@ pub fn flushModule(self: *MachO, comp: *Compilation, prog_node: *std.Progress.No
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return error.UndefinedSymbolReference;
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}
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try self.createDyldPrivateAtom();
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try self.createStubHelperPreambleAtom();
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for (actions.items) |action| switch (action.kind) {
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.none => {},
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.add_got => try self.addGotEntry(action.target),
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.add_stub => try self.addStubEntry(action.target),
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};
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try self.createDyldPrivateAtom();
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try self.writeStubHelperPreamble();
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try self.allocateSpecialSymbols();
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for (self.relocs.keys()) |atom_index| {
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@ -1321,6 +1321,35 @@ fn writeOffsetTableEntry(self: *MachO, index: usize) !void {
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}
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}
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fn writeStubHelperPreamble(self: *MachO) !void {
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if (self.stub_helper_preamble_allocated) return;
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const gpa = self.base.allocator;
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const cpu_arch = self.base.options.target.cpu.arch;
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const size = stubs.calcStubHelperPreambleSize(cpu_arch);
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var buf = try std.ArrayList(u8).initCapacity(gpa, size);
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defer buf.deinit();
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const dyld_private_addr = self.getAtom(self.dyld_private_atom_index.?).getSymbol(self).n_value;
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const dyld_stub_binder_got_addr = blk: {
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const index = self.got_table.lookup.get(self.getGlobalByIndex(self.dyld_stub_binder_index.?)).?;
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const header = self.sections.items(.header)[self.got_section_index.?];
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break :blk header.addr + @sizeOf(u64) * index;
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};
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const header = self.sections.items(.header)[self.stub_helper_section_index.?];
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try stubs.writeStubHelperPreambleCode(.{
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.cpu_arch = cpu_arch,
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.source_addr = header.addr,
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.dyld_private_addr = dyld_private_addr,
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.dyld_stub_binder_got_addr = dyld_stub_binder_got_addr,
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}, buf.writer());
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try self.base.file.?.pwriteAll(buf.items, header.offset);
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self.stub_helper_preamble_allocated = true;
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}
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fn writeStubTableEntry(self: *MachO, index: usize) !void {
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const stubs_sect_id = self.stubs_section_index.?;
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const stub_helper_sect_id = self.stub_helper_section_index.?;
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@ -1401,11 +1430,6 @@ fn writeStubTableEntry(self: *MachO, index: usize) !void {
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}
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}
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fn writePtrWidthAtom(self: *MachO, atom_index: Atom.Index) !void {
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var buffer: [@sizeOf(u64)]u8 = [_]u8{0} ** @sizeOf(u64);
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try self.writeAtom(atom_index, &buffer);
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}
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fn markRelocsDirtyByTarget(self: *MachO, target: SymbolWithLoc) void {
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log.debug("marking relocs dirty by target: {}", .{target});
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// TODO: reverse-lookup might come in handy here
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@ -1492,131 +1516,8 @@ fn createDyldPrivateAtom(self: *MachO) !void {
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sym.n_value = try self.allocateAtom(atom_index, atom.size, @alignOf(u64));
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log.debug("allocated dyld_private atom at 0x{x}", .{sym.n_value});
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try self.writePtrWidthAtom(atom_index);
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}
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fn createStubHelperPreambleAtom(self: *MachO) !void {
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if (self.stub_helper_preamble_atom_index != null) return;
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const gpa = self.base.allocator;
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const arch = self.base.options.target.cpu.arch;
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const size: u5 = switch (arch) {
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.x86_64 => 15,
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.aarch64 => 6 * @sizeOf(u32),
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else => unreachable,
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};
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const atom_index = try self.createAtom();
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const atom = self.getAtomPtr(atom_index);
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atom.size = size;
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const required_alignment: u32 = switch (arch) {
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.x86_64 => 1,
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.aarch64 => @alignOf(u32),
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else => unreachable,
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};
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const sym = atom.getSymbolPtr(self);
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sym.n_type = macho.N_SECT;
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sym.n_sect = self.stub_helper_section_index.? + 1;
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const dyld_private = self.getAtom(self.dyld_private_atom_index.?).getSymbolWithLoc();
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const dyld_stub_binder = self.globals.items[self.dyld_stub_binder_index.?];
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const code = try gpa.alloc(u8, size);
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defer gpa.free(code);
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mem.set(u8, code, 0);
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switch (arch) {
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.x86_64 => {
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// lea %r11, [rip + disp]
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code[0] = 0x4c;
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code[1] = 0x8d;
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code[2] = 0x1d;
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// push %r11
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code[7] = 0x41;
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code[8] = 0x53;
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// jmp [rip + disp]
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code[9] = 0xff;
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code[10] = 0x25;
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try Atom.addRelocations(self, atom_index, &[_]Relocation{ .{
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.type = .signed,
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.target = dyld_private,
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.offset = 3,
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.addend = 0,
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.pcrel = true,
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.length = 2,
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}, .{
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.type = .got,
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.target = dyld_stub_binder,
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.offset = 11,
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.addend = 0,
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.pcrel = true,
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.length = 2,
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} });
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},
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.aarch64 => {
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// adrp x17, 0
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mem.writeIntLittle(u32, code[0..][0..4], aarch64.Instruction.adrp(.x17, 0).toU32());
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// add x17, x17, 0
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mem.writeIntLittle(u32, code[4..][0..4], aarch64.Instruction.add(.x17, .x17, 0, false).toU32());
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// stp x16, x17, [sp, #-16]!
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mem.writeIntLittle(u32, code[8..][0..4], aarch64.Instruction.stp(
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.x16,
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.x17,
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aarch64.Register.sp,
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aarch64.Instruction.LoadStorePairOffset.pre_index(-16),
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).toU32());
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// adrp x16, 0
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mem.writeIntLittle(u32, code[12..][0..4], aarch64.Instruction.adrp(.x16, 0).toU32());
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// ldr x16, [x16, 0]
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mem.writeIntLittle(u32, code[16..][0..4], aarch64.Instruction.ldr(
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.x16,
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.x16,
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aarch64.Instruction.LoadStoreOffset.imm(0),
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).toU32());
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// br x16
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mem.writeIntLittle(u32, code[20..][0..4], aarch64.Instruction.br(.x16).toU32());
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try Atom.addRelocations(self, atom_index, &[_]Relocation{ .{
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.type = .page,
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.target = dyld_private,
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.offset = 0,
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.addend = 0,
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.pcrel = true,
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.length = 2,
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}, .{
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.type = .pageoff,
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.target = dyld_private,
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.offset = 4,
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.addend = 0,
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.pcrel = false,
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.length = 2,
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}, .{
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.type = .got_page,
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.target = dyld_stub_binder,
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.offset = 12,
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.addend = 0,
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.pcrel = true,
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.length = 2,
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}, .{
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.type = .got_pageoff,
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.target = dyld_stub_binder,
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.offset = 16,
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.addend = 0,
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.pcrel = false,
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.length = 2,
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} });
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},
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else => unreachable,
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}
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self.stub_helper_preamble_atom_index = atom_index;
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sym.n_value = try self.allocateAtom(atom_index, size, required_alignment);
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log.debug("allocated stub preamble atom at 0x{x}", .{sym.n_value});
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try self.writeAtom(atom_index, code);
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var buffer: [@sizeOf(u64)]u8 = [_]u8{0} ** @sizeOf(u64);
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try self.writeAtom(atom_index, &buffer);
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}
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fn createThreadLocalDescriptorAtom(self: *MachO, target: SymbolWithLoc) !Atom.Index {
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@ -3415,7 +3316,7 @@ fn populateLazyBindOffsetsInStubHelper(self: *MachO, lazy_bind: LazyBind) !void
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if (lazy_bind.size() == 0) return;
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const stub_helper_section_index = self.stub_helper_section_index.?;
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assert(self.stub_helper_preamble_atom_index != null);
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assert(self.stub_helper_preamble_allocated);
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const header = self.sections.items(.header)[stub_helper_section_index];
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