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Merged
kubkon merged 2 commits into from
Jan 31, 2024
Merged

macho: misc fixes and improvements #18761

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1ee628a
macho: improve error msg when relaxing GOT fails
kubkon Jan 29, 2024
d496651
x86_64+macho: emit .got instead of .got_load relocs
kubkon Jan 29, 2024
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8 changes: 5 additions & 3 deletions src/arch/x86_64/Emit.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,7 @@ pub fn emitMir(emit: *Emit) Error!void {
.pcrel = true,
.has_subtractor = false,
.length = 2,
.symbolnum = 0,
.symbolnum = @intCast(symbol.sym_index),
},
});
} else if (emit.lower.bin_file.cast(link.File.Coff)) |coff_file| {
Expand Down Expand Up @@ -165,7 +165,9 @@ pub fn emitMir(emit: *Emit) Error!void {
const @"type": link.File.MachO.Relocation.Type = if (sym.flags.needs_zig_got and !is_obj_or_static_lib)
.zig_got_load
else if (sym.flags.needs_got)
.got_load
// TODO: it is possible to emit .got_load here that can potentially be relaxed
// however this requires always to use a MOVQ mnemonic
.got
else if (sym.flags.tlv)
.tlv
else
Expand All @@ -180,7 +182,7 @@ pub fn emitMir(emit: *Emit) Error!void {
.pcrel = true,
.has_subtractor = false,
.length = 2,
.symbolnum = 0,
.symbolnum = @intCast(data.sym_index),
},
});
} else unreachable,
Expand Down
34 changes: 27 additions & 7 deletions src/link/MachO/Atom.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -546,8 +546,8 @@ pub fn resolveRelocs(self: Atom, macho_file: *MachO, buffer: []u8) !void {

relocs_log.debug("{x}: {s}", .{ self.value, name });

var has_error = false;
var stream = std.io.fixedBufferStream(buffer);

var i: usize = 0;
while (i < relocs.len) : (i += 1) {
const rel = relocs[i];
Expand All @@ -562,25 +562,34 @@ pub fn resolveRelocs(self: Atom, macho_file: *MachO, buffer: []u8) !void {
self.resolveRelocInner(rel, subtractor, buffer, macho_file, stream.writer()) catch |err| {
switch (err) {
error.RelaxFail => {
const target = switch (rel.tag) {
.@"extern" => rel.getTargetSymbol(macho_file).getName(macho_file),
.local => rel.getTargetAtom(macho_file).getName(macho_file),
};
try macho_file.reportParseError2(
file.getIndex(),
"{s}: 0x{x}: failed to relax relocation: in {s}",
.{ name, rel.offset, @tagName(rel.type) },
"{s}: 0x{x}: 0x{x}: failed to relax relocation: type {s}, target {s}",
.{ name, self.value, rel.offset, @tagName(rel.type), target },
);
return error.ResolveFailed;
has_error = true;
},
error.RelaxFailUnexpectedInstruction => has_error = true,
else => |e| return e,
}
};
}

if (has_error) return error.ResolveFailed;
}

const ResolveError = error{
RelaxFail,
RelaxFailUnexpectedInstruction,
NoSpaceLeft,
DivisionByZero,
UnexpectedRemainder,
Overflow,
OutOfMemory,
};

fn resolveRelocInner(
Expand Down Expand Up @@ -704,7 +713,7 @@ fn resolveRelocInner(
if (rel.getTargetSymbol(macho_file).flags.has_got) {
try writer.writeInt(i32, @intCast(G + A - P), .little);
} else {
try x86_64.relaxGotLoad(code[rel_offset - 3 ..]);
try x86_64.relaxGotLoad(self, code[rel_offset - 3 ..], rel, macho_file);
try writer.writeInt(i32, @intCast(S + A - P), .little);
}
},
Expand Down Expand Up @@ -898,15 +907,26 @@ fn resolveRelocInner(
}

const x86_64 = struct {
fn relaxGotLoad(code: []u8) error{RelaxFail}!void {
fn relaxGotLoad(self: Atom, code: []u8, rel: Relocation, macho_file: *MachO) ResolveError!void {
const old_inst = disassemble(code) orelse return error.RelaxFail;
switch (old_inst.encoding.mnemonic) {
.mov => {
const inst = Instruction.new(old_inst.prefix, .lea, &old_inst.ops) catch return error.RelaxFail;
relocs_log.debug(" relaxing {} => {}", .{ old_inst.encoding, inst.encoding });
encode(&.{inst}, code) catch return error.RelaxFail;
},
else => return error.RelaxFail,
else => |x| {
var err = try macho_file.addErrorWithNotes(2);
try err.addMsg(macho_file, "{s}: 0x{x}: 0x{x}: failed to relax relocation of type {s}", .{
self.getName(macho_file),
self.value,
rel.offset,
@tagName(rel.type),
});
try err.addNote(macho_file, "expected .mov instruction but found .{s}", .{@tagName(x)});
try err.addNote(macho_file, "while parsing {}", .{self.getFile(macho_file).fmtPath()});
return error.RelaxFailUnexpectedInstruction;
},
}
}

Expand Down
15 changes: 6 additions & 9 deletions src/link/MachO/ZigObject.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -390,7 +390,7 @@ pub fn getDeclVAddr(
.pcrel = false,
.has_subtractor = false,
.length = 3,
.symbolnum = 0,
.symbolnum = @intCast(sym.nlist_idx),
},
});
return vaddr;
Expand All @@ -416,7 +416,7 @@ pub fn getAnonDeclVAddr(
.pcrel = false,
.has_subtractor = false,
.length = 3,
.symbolnum = 0,
.symbolnum = @intCast(sym.nlist_idx),
},
});
return vaddr;
Expand Down Expand Up @@ -856,21 +856,18 @@ fn createTlvDescriptor(
atom.alignment = alignment;
atom.size = size;

const tlv_bootstrap_index = blk: {
const index = try self.getGlobalSymbol(macho_file, "_tlv_bootstrap", null);
break :blk self.symbols.items[index];
};
const tlv_bootstrap_index = try self.getGlobalSymbol(macho_file, "_tlv_bootstrap", null);
try atom.addReloc(macho_file, .{
.tag = .@"extern",
.offset = 0,
.target = tlv_bootstrap_index,
.target = self.symbols.items[tlv_bootstrap_index],
.addend = 0,
.type = .unsigned,
.meta = .{
.pcrel = false,
.has_subtractor = false,
.length = 3,
.symbolnum = 0,
.symbolnum = @intCast(tlv_bootstrap_index),
},
});
try atom.addReloc(macho_file, .{
Expand All @@ -883,7 +880,7 @@ fn createTlvDescriptor(
.pcrel = false,
.has_subtractor = false,
.length = 3,
.symbolnum = 0,
.symbolnum = @intCast(macho_file.getSymbol(init_sym_index).nlist_idx),
},
});

Expand Down