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zld: resolve GOT loads and stubs

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This commit is contained in:
Jakub Konka
2021-05-03 14:33:13 +02:00
parent 68ebc7cba0
commit fcd57f0857
2 changed files with 34 additions and 42 deletions
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7
src/link/MachO/Symbol.zig
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@@ -97,6 +97,13 @@ pub fn cast(base: *Symbol, comptime T: type) ?*T {
return @fieldParentPtr(T, "base", base);
}
pub fn getTopmostAlias(base: *Symbol) *Symbol {
if (base.alias) |alias| {
return alias.getTopmostAlias();
}
return base;
}
pub fn isStab(sym: macho.nlist_64) bool {
return (macho.N_STAB & sym.n_type) != 0;
}

69
src/link/MachO/Zld.zig
View File

@@ -83,8 +83,8 @@ strtab_dir: std.StringHashMapUnmanaged(u32) = .{},
threadlocal_offsets: std.ArrayListUnmanaged(u64) = .{},
local_rebases: std.ArrayListUnmanaged(Pointer) = .{},
stubs: std.StringArrayHashMapUnmanaged(*Symbol) = .{},
got_entries: std.StringArrayHashMapUnmanaged(*Symbol) = .{},
stubs: std.ArrayListUnmanaged(*Symbol) = .{},
got_entries: std.ArrayListUnmanaged(*Symbol) = .{},
stub_helper_stubs_start_off: ?u64 = null,
@@ -200,9 +200,9 @@ pub fn link(self: *Zld, files: []const []const u8, out_path: []const u8) !void {
try self.populateMetadata();
try self.parseInputFiles(files);
try self.resolveSymbols();
self.printSymbols();
// self.printSymbols();
try self.resolveStubsAndGotEntries();
return error.Unfinished;
// try self.resolveStubsAndGotEntries();
// try self.updateMetadata();
// try self.sortSections();
// try self.allocateTextSegment();
@@ -1413,8 +1413,8 @@ fn resolveSymbols(self: *Zld) !void {
}
fn resolveStubsAndGotEntries(self: *Zld) !void {
for (self.objects.items) |object, object_id| {
log.debug("resolving stubs and got entries from {s}", .{object.name});
for (self.objects.items) |object| {
log.warn("resolving stubs and got entries from {s}", .{object.name});
for (object.sections.items) |sect| {
const relocs = sect.relocs orelse continue;
@@ -1422,42 +1422,31 @@ fn resolveStubsAndGotEntries(self: *Zld) !void {
switch (rel.@"type") {
.unsigned => continue,
.got_page, .got_page_off, .got_load, .got => {
const sym = object.symtab.items[rel.target.symbol];
const sym_name = object.getString(sym.n_strx);
const sym = rel.target.symbol.getTopmostAlias();
if (sym.got_index != null) continue;
if (self.got_entries.contains(sym_name)) continue;
const index = @intCast(u32, self.got_entries.items.len);
sym.got_index = index;
try self.got_entries.append(self.allocator, sym);
// TODO clean this up
const is_import = self.symtab.get(sym_name).?.tag == .import;
var name = try self.allocator.dupe(u8, sym_name);
const index = @intCast(u32, self.got_entries.items().len);
try self.got_entries.putNoClobber(self.allocator, name, .{
.tag = if (is_import) .import else .local,
.index = index,
.target_addr = 0,
.file = if (is_import) 0 else @intCast(u16, object_id),
});
log.debug(" | found GOT entry {s}: {}", .{ sym_name, self.got_entries.get(sym_name) });
log.warn(" | found GOT entry {s}: {*}", .{ sym.name, sym });
},
else => {
if (rel.target != .symbol) continue;
const sym = object.symtab.items[rel.target.symbol];
const sym_name = object.getString(sym.n_strx);
const sym = rel.target.symbol.getTopmostAlias();
assert(sym.@"type" != .unresolved);
if (!Symbol.isUndef(sym)) continue;
if (sym.stubs_index != null) continue;
if (sym.cast(Symbol.Regular)) |reg| {
if (!reg.weak_ref) continue;
}
const in_globals = self.symtab.get(sym_name) orelse unreachable;
const index = @intCast(u32, self.stubs.items.len);
sym.stubs_index = index;
try self.stubs.append(self.allocator, sym);
if (in_globals.tag != .import) continue;
if (self.stubs.contains(sym_name)) continue;
var name = try self.allocator.dupe(u8, sym_name);
const index = @intCast(u32, self.stubs.items().len);
try self.stubs.putNoClobber(self.allocator, name, index);
log.debug(" | found stub {s}: {}", .{ sym_name, self.stubs.get(sym_name) });
log.warn(" | found stub {s}: {*}", .{ sym.name, sym });
},
}
}
@@ -1465,16 +1454,12 @@ fn resolveStubsAndGotEntries(self: *Zld) !void {
}
// Finally, put dyld_stub_binder as the final GOT entry
var name = try self.allocator.dupe(u8, "dyld_stub_binder");
const index = @intCast(u32, self.got_entries.items().len);
try self.got_entries.putNoClobber(self.allocator, name, .{
.tag = .import,
.index = index,
.target_addr = 0,
.file = 0,
});
const sym = self.imports.get("dyld_stub_binder") orelse unreachable;
const index = @intCast(u32, self.got_entries.items.len);
sym.got_index = index;
try self.got_entries.append(self.allocator, sym);
log.debug(" | found GOT entry dyld_stub_binder: {}", .{self.got_entries.get("dyld_stub_binder")});
log.warn(" | found GOT entry {s}: {*}", .{ sym.name, sym });
}
fn resolveRelocsAndWriteSections(self: *Zld) !void {