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zld: handle dynamic binding of proxies for objc correctly

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This commit is contained in:
Jakub Konka 2021-06-22 11:17:43 +02:00
parent 0736365fa4
commit 1ff3ebffa3
2 changed files with 49 additions and 1 deletions
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5
src/link/MachO/Symbol.zig
View File

@ -85,6 +85,11 @@ pub const Regular = struct {
pub const Proxy = struct {
base: Symbol,
bind_info: std.ArrayListUnmanaged(struct {
segment_id: u16,
address: u64,
}) = .{},
/// Dylib or stub where to locate this symbol.
/// null means self-reference.
file: ?union(enum) {

45
src/link/MachO/Zld.zig
View File

@ -263,6 +263,7 @@ pub fn link(self: *Zld, files: []const []const u8, out_path: []const u8, args: L
self.allocateLinkeditSegment();
try self.allocateSymbols();
try self.allocateTentativeSymbols();
try self.allocateProxiesBindAddresses();
try self.flush();
}
@ -1346,6 +1347,30 @@ fn allocateTentativeSymbols(self: *Zld) !void {
}
}
fn allocateProxiesBindAddresses(self: *Zld) !void {
for (self.objects.items) |object| {
for (object.sections.items) |sect| {
const relocs = sect.relocs orelse continue;
for (relocs) |rel| {
if (rel.@"type" != .unsigned) continue; // GOT is currently special-cased
if (rel.target != .symbol) continue;
const sym = rel.target.symbol.getTopmostAlias();
if (sym.cast(Symbol.Proxy)) |proxy| {
const target_map = sect.target_map orelse continue;
const target_seg = self.load_commands.items[target_map.segment_id].Segment;
const target_sect = target_seg.sections.items[target_map.section_id];
try proxy.bind_info.append(self.allocator, .{
.segment_id = target_map.segment_id,
.address = target_sect.addr + target_map.offset + rel.offset,
});
}
}
}
}
}
fn writeStubHelperCommon(self: *Zld) !void {
const text_segment = &self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const stub_helper = &text_segment.sections.items[self.stub_helper_section_index.?];
@ -1863,6 +1888,7 @@ fn resolveStubsAndGotEntries(self: *Zld) !void {
const relocs = sect.relocs orelse continue;
for (relocs) |rel| {
switch (rel.@"type") {
.unsigned => continue,
.got_page, .got_page_off, .got_load, .got, .pointer_to_got => {
const sym = rel.target.symbol.getTopmostAlias();
if (sym.got_index != null) continue;
@ -2090,7 +2116,10 @@ fn relocTargetAddr(self: *Zld, object: *const Object, target: reloc.Relocation.T
const segment = self.load_commands.items[self.text_segment_cmd_index.?].Segment;
const stubs = segment.sections.items[self.stubs_section_index.?];
const stubs_index = proxy.base.stubs_index orelse {
log.err("expected stubs index when relocating symbol '{s}'", .{final.name});
if (proxy.bind_info.items.len > 0) {
break :blk 0; // Dynamically bound by dyld.
}
log.err("expected stubs index or dynamic bind address when relocating symbol '{s}'", .{final.name});
log.err("this is an internal linker error", .{});
return error.FailedToResolveRelocationTarget;
};
@ -2640,6 +2669,20 @@ fn writeBindInfoTable(self: *Zld) !void {
}
}
for (self.imports.values()) |sym| {
if (sym.cast(Symbol.Proxy)) |proxy| {
for (proxy.bind_info.items) |info| {
const seg = self.load_commands.items[info.segment_id].Segment;
try pointers.append(.{
.offset = info.address - seg.inner.vmaddr,
.segment_id = info.segment_id,
.dylib_ordinal = proxy.dylibOrdinal(),
.name = proxy.base.name,
});
}
}
}
if (self.tlv_section_index) |idx| {
const seg = self.load_commands.items[self.data_segment_cmd_index.?].Segment;
const sect = seg.sections.items[idx];