Commit 7be983ac92

Jakub Konka <kubkon@jakubkonka.com>
2023-10-13 14:54:52
elf: create new synthetic section ZigGotSection
1 parent 9b6337a
src/arch/aarch64/CodeGen.zig
@@ -4318,8 +4318,8 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
             if (self.bin_file.cast(link.File.Elf)) |elf_file| {
                 const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
                 const sym = elf_file.symbol(sym_index);
-                _ = try sym.getOrCreateGotEntry(sym_index, elf_file);
-                const got_addr = @as(u32, @intCast(sym.gotAddress(elf_file)));
+                _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
+                const got_addr = @as(u32, @intCast(sym.zigGotAddress(elf_file)));
                 try self.genSetReg(Type.usize, .x30, .{ .memory = got_addr });
             } else if (self.bin_file.cast(link.File.MachO)) |macho_file| {
                 const atom = try macho_file.getOrCreateAtomForDecl(func.owner_decl);
src/arch/arm/CodeGen.zig
@@ -4304,8 +4304,8 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
             if (self.bin_file.cast(link.File.Elf)) |elf_file| {
                 const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
                 const sym = elf_file.symbol(sym_index);
-                _ = try sym.getOrCreateGotEntry(sym_index, elf_file);
-                const got_addr = @as(u32, @intCast(sym.gotAddress(elf_file)));
+                _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
+                const got_addr = @as(u32, @intCast(sym.zigGotAddress(elf_file)));
                 try self.genSetReg(Type.usize, .lr, .{ .memory = got_addr });
             } else if (self.bin_file.cast(link.File.MachO)) |_| {
                 unreachable; // unsupported architecture for MachO
src/arch/riscv64/CodeGen.zig
@@ -1754,8 +1754,8 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
                 .func => |func| {
                     const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
                     const sym = elf_file.symbol(sym_index);
-                    _ = try sym.getOrCreateGotEntry(sym_index, elf_file);
-                    const got_addr = @as(u32, @intCast(sym.gotAddress(elf_file)));
+                    _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
+                    const got_addr = @as(u32, @intCast(sym.zigGotAddress(elf_file)));
                     try self.genSetReg(Type.usize, .ra, .{ .memory = got_addr });
                     _ = try self.addInst(.{
                         .tag = .jalr,
src/arch/sparc64/CodeGen.zig
@@ -1349,8 +1349,8 @@ fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallModifier
                     const got_addr = if (self.bin_file.cast(link.File.Elf)) |elf_file| blk: {
                         const sym_index = try elf_file.getOrCreateMetadataForDecl(func.owner_decl);
                         const sym = elf_file.symbol(sym_index);
-                        _ = try sym.getOrCreateGotEntry(sym_index, elf_file);
-                        break :blk @as(u32, @intCast(sym.gotAddress(elf_file)));
+                        _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
+                        break :blk @as(u32, @intCast(sym.zigGotAddress(elf_file)));
                     } else unreachable;
 
                     try self.genSetReg(Type.usize, .o7, .{ .memory = got_addr });
src/arch/x86_64/CodeGen.zig
@@ -9189,8 +9189,7 @@ fn genCall(self: *Self, info: union(enum) {
                 if (self.bin_file.cast(link.File.Elf)) |elf_file| {
                     const sym_index = try elf_file.getOrCreateMetadataForDecl(owner_decl);
                     const sym = elf_file.symbol(sym_index);
-                    sym.flags.needs_got = true;
-                    _ = try sym.getOrCreateGotEntry(sym_index, elf_file);
+                    _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
                     _ = try self.addInst(.{
                         .tag = .call,
                         .ops = .direct_got_reloc,
@@ -11637,8 +11636,7 @@ fn genLazySymbolRef(
         const sym_index = elf_file.getOrCreateMetadataForLazySymbol(lazy_sym) catch |err|
             return self.fail("{s} creating lazy symbol", .{@errorName(err)});
         const sym = elf_file.symbol(sym_index);
-        sym.flags.needs_got = true;
-        _ = try sym.getOrCreateGotEntry(sym_index, elf_file);
+        _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
         const reloc = Mir.Reloc{
             .atom_index = try self.owner.getSymbolIndex(self),
             .sym_index = sym.esym_index,
src/link/Elf/Atom.zig
@@ -367,8 +367,16 @@ pub fn scanRelocs(self: Atom, elf_file: *Elf, code: ?[]const u8, undefs: anytype
                 try self.scanReloc(symbol, rel, dynAbsRelocAction(symbol, elf_file), elf_file);
             },
 
+            // TODO I have temporarily repurposed those for handling .zig.got indirection
+            // but we should probably claim unused custom values for incremental linking
+            // that get rewritten to standard relocs when lowering to a relocatable object
+            // file.
             elf.R_X86_64_GOT32,
             elf.R_X86_64_GOT64,
+            => {
+                assert(symbol.flags.has_zig_got);
+            },
+
             elf.R_X86_64_GOTPC32,
             elf.R_X86_64_GOTPC64,
             elf.R_X86_64_GOTPCREL,
@@ -736,6 +744,8 @@ pub fn resolveRelocsAlloc(self: Atom, elf_file: *Elf, code: []u8) !void {
                 null;
             break :blk if (shndx) |index| @as(i64, @intCast(elf_file.shdrs.items[index].sh_addr)) else 0;
         };
+        // Address of the .zig.got table entry if any.
+        const ZIG_GOT = @as(i64, @intCast(target.zigGotAddress(elf_file)));
         // Relative offset to the start of the global offset table.
         const G = @as(i64, @intCast(target.gotAddress(elf_file))) - GOT;
         // // Address of the thread pointer.
@@ -796,8 +806,12 @@ pub fn resolveRelocsAlloc(self: Atom, elf_file: *Elf, code: []u8) !void {
             elf.R_X86_64_32 => try cwriter.writeIntLittle(u32, @as(u32, @truncate(@as(u64, @intCast(S + A))))),
             elf.R_X86_64_32S => try cwriter.writeIntLittle(i32, @as(i32, @truncate(S + A))),
 
-            elf.R_X86_64_GOT32 => try cwriter.writeIntLittle(u32, @as(u32, @intCast(G + GOT + A))),
-            elf.R_X86_64_GOT64 => try cwriter.writeIntLittle(u64, @as(u64, @intCast(G + GOT + A))),
+            // TODO I have temporarily repurposed those for handling .zig.got indirection
+            // but we should probably claim unused custom values for incremental linking
+            // that get rewritten to standard relocs when lowering to a relocatable object
+            // file.
+            elf.R_X86_64_GOT32 => try cwriter.writeIntLittle(u32, @as(u32, @intCast(ZIG_GOT + A))),
+            elf.R_X86_64_GOT64 => try cwriter.writeIntLittle(u64, @as(u64, @intCast(ZIG_GOT + A))),
 
             elf.R_X86_64_TPOFF32 => try cwriter.writeIntLittle(i32, @as(i32, @truncate(S + A - TP))),
             elf.R_X86_64_TPOFF64 => try cwriter.writeIntLittle(i64, S + A - TP),
src/link/Elf/Symbol.zig
@@ -137,19 +137,6 @@ pub fn copyRelAddress(symbol: Symbol, elf_file: *Elf) u64 {
     return shdr.sh_addr + symbol.value;
 }
 
-const GetOrCreateGotEntryResult = struct {
-    found_existing: bool,
-    index: GotSection.Index,
-};
-
-pub fn getOrCreateGotEntry(symbol: *Symbol, symbol_index: Index, elf_file: *Elf) !GetOrCreateGotEntryResult {
-    assert(symbol.flags.needs_got);
-    if (symbol.flags.has_got) return .{ .found_existing = true, .index = symbol.extra(elf_file).?.got };
-    const index = try elf_file.got.addGotSymbol(symbol_index, elf_file);
-    symbol.flags.has_got = true;
-    return .{ .found_existing = false, .index = index };
-}
-
 pub fn tlsGdAddress(symbol: Symbol, elf_file: *Elf) u64 {
     if (!symbol.flags.has_tlsgd) return 0;
     const extras = symbol.extra(elf_file).?;
@@ -171,6 +158,23 @@ pub fn tlsDescAddress(symbol: Symbol, elf_file: *Elf) u64 {
     return entry.address(elf_file);
 }
 
+const GetOrCreateZigGotEntryResult = struct {
+    found_existing: bool,
+    index: ZigGotSection.Index,
+};
+
+pub fn getOrCreateZigGotEntry(symbol: *Symbol, symbol_index: Index, elf_file: *Elf) !GetOrCreateZigGotEntryResult {
+    if (symbol.flags.has_zig_got) return .{ .found_existing = true, .index = symbol.extra(elf_file).?.zig_got };
+    const index = try elf_file.zig_got.addSymbol(symbol_index, elf_file);
+    return .{ .found_existing = false, .index = index };
+}
+
+pub fn zigGotAddress(symbol: Symbol, elf_file: *Elf) u64 {
+    if (!symbol.flags.has_zig_got) return 0;
+    const extras = symbol.extra(elf_file).?;
+    return elf_file.zig_got.entryAddress(extras.zig_got, elf_file);
+}
+
 pub fn dsoAlignment(symbol: Symbol, elf_file: *Elf) !u64 {
     const file_ptr = symbol.file(elf_file) orelse return 0;
     assert(file_ptr == .shared_object);
@@ -367,6 +371,9 @@ pub const Flags = packed struct {
     /// Whether the symbol contains TLSDESC indirection.
     needs_tlsdesc: bool = false,
     has_tlsdesc: bool = false,
+
+    /// Whether the symbol contains .zig.got indirection.
+    has_zig_got: bool = false,
 };
 
 pub const Extra = struct {
@@ -378,6 +385,7 @@ pub const Extra = struct {
     tlsgd: u32 = 0,
     gottp: u32 = 0,
     tlsdesc: u32 = 0,
+    zig_got: u32 = 0,
 };
 
 pub const Index = u32;
@@ -397,4 +405,5 @@ const Object = @import("Object.zig");
 const PltSection = synthetic_sections.PltSection;
 const SharedObject = @import("SharedObject.zig");
 const Symbol = @This();
+const ZigGotSection = synthetic_sections.ZigGotSection;
 const ZigModule = @import("ZigModule.zig");
src/link/Elf/synthetic_sections.zig
@@ -220,6 +220,191 @@ pub const DynamicSection = struct {
     }
 };
 
+pub const ZigGotSection = struct {
+    entries: std.ArrayListUnmanaged(Symbol.Index) = .{},
+    output_symtab_size: Elf.SymtabSize = .{},
+    flags: Flags = .{},
+
+    const Flags = packed struct {
+        needs_rela: bool = false, // TODO in prep for PIC/PIE and base relocations
+        dirty: bool = false,
+    };
+
+    pub const Index = u32;
+
+    pub fn deinit(zig_got: *ZigGotSection, allocator: Allocator) void {
+        zig_got.entries.deinit(allocator);
+    }
+
+    fn allocateEntry(zig_got: *ZigGotSection, allocator: Allocator) !Index {
+        try zig_got.entries.ensureUnusedCapacity(allocator, 1);
+        // TODO add free list
+        const index = @as(Index, @intCast(zig_got.entries.items.len));
+        _ = zig_got.entries.addOneAssumeCapacity();
+        zig_got.flags.dirty = true;
+        return index;
+    }
+
+    pub fn addSymbol(zig_got: *ZigGotSection, sym_index: Symbol.Index, elf_file: *Elf) !Index {
+        const index = try zig_got.allocateEntry(elf_file.base.allocator);
+        const entry = &zig_got.entries.items[index];
+        entry.* = sym_index;
+        const symbol = elf_file.symbol(sym_index);
+        symbol.flags.has_zig_got = true;
+        if (symbol.extra(elf_file)) |extra| {
+            var new_extra = extra;
+            new_extra.zig_got = index;
+            symbol.setExtra(new_extra, elf_file);
+        } else try symbol.addExtra(.{ .zig_got = index }, elf_file);
+        return index;
+    }
+
+    pub fn entryOffset(zig_got: ZigGotSection, index: Index, elf_file: *Elf) u64 {
+        _ = zig_got;
+        const entry_size = elf_file.archPtrWidthBytes();
+        const shdr = elf_file.shdrs.items[elf_file.zig_got_section_index.?];
+        return shdr.sh_offset + @as(u64, entry_size) * index;
+    }
+
+    pub fn entryAddress(zig_got: ZigGotSection, index: Index, elf_file: *Elf) u64 {
+        _ = zig_got;
+        const entry_size = elf_file.archPtrWidthBytes();
+        const shdr = elf_file.shdrs.items[elf_file.zig_got_section_index.?];
+        return shdr.sh_addr + @as(u64, entry_size) * index;
+    }
+
+    pub fn size(zig_got: ZigGotSection, elf_file: *Elf) usize {
+        return elf_file.archPtrWidthBytes() * zig_got.entries.items.len;
+    }
+
+    pub fn writeOne(zig_got: *ZigGotSection, elf_file: *Elf, index: Index) !void {
+        if (zig_got.flags.dirty) {
+            const needed_size = zig_got.size(elf_file);
+            try elf_file.growAllocSection(elf_file.zig_got_section_index.?, needed_size);
+            zig_got.flags.dirty = false;
+        }
+        const entry_size: u16 = elf_file.archPtrWidthBytes();
+        const endian = elf_file.base.options.target.cpu.arch.endian();
+        const off = zig_got.entryOffset(index, elf_file);
+        const vaddr = zig_got.entryAddress(index, elf_file);
+        const entry = zig_got.entries.items[index];
+        const value = elf_file.symbol(entry).value;
+        switch (entry_size) {
+            2 => {
+                var buf: [2]u8 = undefined;
+                std.mem.writeInt(u16, &buf, @as(u16, @intCast(value)), endian);
+                try elf_file.base.file.?.pwriteAll(&buf, off);
+            },
+            4 => {
+                var buf: [4]u8 = undefined;
+                std.mem.writeInt(u32, &buf, @as(u32, @intCast(value)), endian);
+                try elf_file.base.file.?.pwriteAll(&buf, off);
+            },
+            8 => {
+                var buf: [8]u8 = undefined;
+                std.mem.writeInt(u64, &buf, value, endian);
+                try elf_file.base.file.?.pwriteAll(&buf, off);
+
+                if (elf_file.base.child_pid) |pid| {
+                    switch (builtin.os.tag) {
+                        .linux => {
+                            var local_vec: [1]std.os.iovec_const = .{.{
+                                .iov_base = &buf,
+                                .iov_len = buf.len,
+                            }};
+                            var remote_vec: [1]std.os.iovec_const = .{.{
+                                .iov_base = @as([*]u8, @ptrFromInt(@as(usize, @intCast(vaddr)))),
+                                .iov_len = buf.len,
+                            }};
+                            const rc = std.os.linux.process_vm_writev(pid, &local_vec, &remote_vec, 0);
+                            switch (std.os.errno(rc)) {
+                                .SUCCESS => assert(rc == buf.len),
+                                else => |errno| log.warn("process_vm_writev failure: {s}", .{@tagName(errno)}),
+                            }
+                        },
+                        else => return error.HotSwapUnavailableOnHostOperatingSystem,
+                    }
+                }
+            },
+            else => unreachable,
+        }
+    }
+
+    pub fn writeAll(zig_got: ZigGotSection, elf_file: *Elf, writer: anytype) !void {
+        for (zig_got.entries.items) |entry| {
+            const symbol = elf_file.symbol(entry);
+            const value = symbol.address(.{ .plt = false }, elf_file);
+            try writeInt(value, elf_file, writer);
+        }
+    }
+
+    pub fn updateSymtabSize(zig_got: *ZigGotSection, elf_file: *Elf) void {
+        _ = elf_file;
+        zig_got.output_symtab_size.nlocals = @as(u32, @intCast(zig_got.entries.items.len));
+    }
+
+    pub fn updateStrtab(zig_got: ZigGotSection, elf_file: *Elf) !void {
+        const gpa = elf_file.base.allocator;
+        for (zig_got.entries.items) |entry| {
+            const symbol_name = elf_file.symbol(entry).name(elf_file);
+            const name = try std.fmt.allocPrint(gpa, "{s}$ziggot", .{symbol_name});
+            defer gpa.free(name);
+            _ = try elf_file.strtab.insert(gpa, name);
+        }
+    }
+
+    pub fn writeSymtab(zig_got: ZigGotSection, elf_file: *Elf, ctx: anytype) !void {
+        const gpa = elf_file.base.allocator;
+        for (zig_got.entries.items, ctx.ilocal.., 0..) |entry, ilocal, index| {
+            const symbol = elf_file.symbol(entry);
+            const symbol_name = symbol.name(elf_file);
+            const name = try std.fmt.allocPrint(gpa, "{s}$ziggot", .{symbol_name});
+            defer gpa.free(name);
+            const st_name = try elf_file.strtab.insert(gpa, name);
+            const st_value = zig_got.entryAddress(@intCast(index), elf_file);
+            const st_size = elf_file.archPtrWidthBytes();
+            ctx.symtab[ilocal] = .{
+                .st_name = st_name,
+                .st_info = elf.STT_OBJECT,
+                .st_other = 0,
+                .st_shndx = elf_file.zig_got_section_index.?,
+                .st_value = st_value,
+                .st_size = st_size,
+            };
+        }
+    }
+
+    const FormatCtx = struct {
+        zig_got: ZigGotSection,
+        elf_file: *Elf,
+    };
+
+    pub fn fmt(zig_got: ZigGotSection, elf_file: *Elf) std.fmt.Formatter(format2) {
+        return .{ .data = .{ .zig_got = zig_got, .elf_file = elf_file } };
+    }
+
+    pub fn format2(
+        ctx: FormatCtx,
+        comptime unused_fmt_string: []const u8,
+        options: std.fmt.FormatOptions,
+        writer: anytype,
+    ) !void {
+        _ = options;
+        _ = unused_fmt_string;
+        try writer.writeAll(".zig.got\n");
+        for (ctx.zig_got.entries.items, 0..) |entry, index| {
+            const symbol = ctx.elf_file.symbol(entry);
+            try writer.print("  {d}@0x{x} => {d}@0x{x} ({s})\n", .{
+                index,
+                ctx.zig_got.entryAddress(@intCast(index), ctx.elf_file),
+                entry,
+                symbol.address(.{}, ctx.elf_file),
+                symbol.name(ctx.elf_file),
+            });
+        }
+    }
+};
+
 pub const GotSection = struct {
     entries: std.ArrayListUnmanaged(Entry) = .{},
     output_symtab_size: Elf.SymtabSize = .{},
@@ -420,17 +605,6 @@ pub const GotSection = struct {
         }
     }
 
-    fn writeInt(value: anytype, elf_file: *Elf, writer: anytype) !void {
-        const entry_size = elf_file.archPtrWidthBytes();
-        const endian = elf_file.base.options.target.cpu.arch.endian();
-        switch (entry_size) {
-            2 => try writer.writeInt(u16, @intCast(value), endian),
-            4 => try writer.writeInt(u32, @intCast(value), endian),
-            8 => try writer.writeInt(u64, @intCast(value), endian),
-            else => unreachable,
-        }
-    }
-
     pub fn addRela(got: GotSection, elf_file: *Elf) !void {
         const is_dyn_lib = elf_file.isDynLib();
         try elf_file.rela_dyn.ensureUnusedCapacity(elf_file.base.allocator, got.numRela(elf_file));
@@ -1327,6 +1501,17 @@ pub const VerneedSection = struct {
     }
 };
 
+fn writeInt(value: anytype, elf_file: *Elf, writer: anytype) !void {
+    const entry_size = elf_file.archPtrWidthBytes();
+    const endian = elf_file.base.options.target.cpu.arch.endian();
+    switch (entry_size) {
+        2 => try writer.writeInt(u16, @intCast(value), endian),
+        4 => try writer.writeInt(u32, @intCast(value), endian),
+        8 => try writer.writeInt(u64, @intCast(value), endian),
+        else => unreachable,
+    }
+}
+
 const assert = std.debug.assert;
 const builtin = @import("builtin");
 const elf = std.elf;
src/link/Elf.zig
@@ -33,16 +33,16 @@ phdrs: std.ArrayListUnmanaged(elf.Elf64_Phdr) = .{},
 
 /// Tracked loadable segments during incremental linking.
 /// The index into the program headers of a PT_LOAD program header with Read and Execute flags
-phdr_load_re_zig_index: ?u16 = null,
+phdr_zig_load_re_index: ?u16 = null,
 /// The index into the program headers of the global offset table.
 /// It needs PT_LOAD and Read flags.
-phdr_got_zig_index: ?u16 = null,
+phdr_zig_got_index: ?u16 = null,
 /// The index into the program headers of a PT_LOAD program header with Read flag
-phdr_load_ro_zig_index: ?u16 = null,
+phdr_zig_load_ro_index: ?u16 = null,
 /// The index into the program headers of a PT_LOAD program header with Write flag
-phdr_load_rw_zig_index: ?u16 = null,
+phdr_zig_load_rw_index: ?u16 = null,
 /// The index into the program headers of a PT_LOAD program header with zerofill data.
-phdr_load_zerofill_zig_index: ?u16 = null,
+phdr_zig_load_zerofill_index: ?u16 = null,
 
 /// Special program headers
 /// PT_PHDR
@@ -99,13 +99,15 @@ plt_got: PltGotSection = .{},
 copy_rel: CopyRelSection = .{},
 /// .rela.plt section
 rela_plt: std.ArrayListUnmanaged(elf.Elf64_Rela) = .{},
+/// .zig.got section
+zig_got: ZigGotSection = .{},
 
 /// Tracked section headers with incremental updates to Zig module
-text_zig_section_index: ?u16 = null,
-rodata_zig_section_index: ?u16 = null,
-data_zig_section_index: ?u16 = null,
-bss_zig_section_index: ?u16 = null,
-got_zig_section_index: ?u16 = null,
+zig_text_section_index: ?u16 = null,
+zig_rodata_section_index: ?u16 = null,
+zig_data_section_index: ?u16 = null,
+zig_bss_section_index: ?u16 = null,
+zig_got_section_index: ?u16 = null,
 debug_info_section_index: ?u16 = null,
 debug_abbrev_section_index: ?u16 = null,
 debug_str_section_index: ?u16 = null,
@@ -479,7 +481,7 @@ pub fn lowerAnonDecl(self: *Elf, decl_val: InternPool.Index, src_loc: Module.Src
         const tv = TypedValue{ .ty = ty, .val = val };
         const name = try std.fmt.allocPrint(gpa, "__anon_{d}", .{@intFromEnum(decl_val)});
         defer gpa.free(name);
-        const res = self.lowerConst(name, tv, self.rodata_zig_section_index.?, src_loc) catch |err| switch (err) {
+        const res = self.lowerConst(name, tv, self.zig_rodata_section_index.?, src_loc) catch |err| switch (err) {
             else => {
                 // TODO improve error message
                 const em = try Module.ErrorMsg.create(gpa, src_loc, "lowerAnonDecl failed with error: {s}", .{
@@ -687,8 +689,8 @@ pub fn initMetadata(self: *Elf) !void {
     const ptr_bit_width = self.base.options.target.ptrBitWidth();
     const is_linux = self.base.options.target.os.tag == .linux;
 
-    if (self.phdr_load_re_zig_index == null) {
-        self.phdr_load_re_zig_index = try self.allocateSegment(.{
+    if (self.phdr_zig_load_re_index == null) {
+        self.phdr_zig_load_re_index = try self.allocateSegment(.{
             .addr = if (ptr_bit_width >= 32) 0x8000000 else 0x8000,
             .memsz = self.base.options.program_code_size_hint,
             .filesz = self.base.options.program_code_size_hint,
@@ -697,11 +699,11 @@ pub fn initMetadata(self: *Elf) !void {
         });
     }
 
-    if (self.phdr_got_zig_index == null) {
+    if (self.phdr_zig_got_index == null) {
         // We really only need ptr alignment but since we are using PROGBITS, linux requires
         // page align.
         const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
-        self.phdr_got_zig_index = try self.allocateSegment(.{
+        self.phdr_zig_got_index = try self.allocateSegment(.{
             .addr = if (ptr_bit_width >= 32) 0x4000000 else 0x4000,
             .memsz = @as(u64, ptr_size) * self.base.options.symbol_count_hint,
             .filesz = @as(u64, ptr_size) * self.base.options.symbol_count_hint,
@@ -710,9 +712,9 @@ pub fn initMetadata(self: *Elf) !void {
         });
     }
 
-    if (self.phdr_load_ro_zig_index == null) {
+    if (self.phdr_zig_load_ro_index == null) {
         const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
-        self.phdr_load_ro_zig_index = try self.allocateSegment(.{
+        self.phdr_zig_load_ro_index = try self.allocateSegment(.{
             .addr = if (ptr_bit_width >= 32) 0xc000000 else 0xa000,
             .memsz = 1024,
             .filesz = 1024,
@@ -721,9 +723,9 @@ pub fn initMetadata(self: *Elf) !void {
         });
     }
 
-    if (self.phdr_load_rw_zig_index == null) {
+    if (self.phdr_zig_load_rw_index == null) {
         const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
-        self.phdr_load_rw_zig_index = try self.allocateSegment(.{
+        self.phdr_zig_load_rw_index = try self.allocateSegment(.{
             .addr = if (ptr_bit_width >= 32) 0x10000000 else 0xc000,
             .memsz = 1024,
             .filesz = 1024,
@@ -732,64 +734,64 @@ pub fn initMetadata(self: *Elf) !void {
         });
     }
 
-    if (self.phdr_load_zerofill_zig_index == null) {
+    if (self.phdr_zig_load_zerofill_index == null) {
         const alignment = if (is_linux) self.page_size else @as(u16, ptr_size);
-        self.phdr_load_zerofill_zig_index = try self.allocateSegment(.{
+        self.phdr_zig_load_zerofill_index = try self.allocateSegment(.{
             .addr = if (ptr_bit_width >= 32) 0x14000000 else 0xf000,
             .memsz = 0,
             .filesz = 0,
             .alignment = alignment,
             .flags = elf.PF_R | elf.PF_W,
         });
-        const phdr = &self.phdrs.items[self.phdr_load_zerofill_zig_index.?];
-        phdr.p_offset = self.phdrs.items[self.phdr_load_rw_zig_index.?].p_offset; // .bss overlaps .data
+        const phdr = &self.phdrs.items[self.phdr_zig_load_zerofill_index.?];
+        phdr.p_offset = self.phdrs.items[self.phdr_zig_load_rw_index.?].p_offset; // .bss overlaps .data
         phdr.p_memsz = 1024;
     }
 
-    if (self.text_zig_section_index == null) {
-        self.text_zig_section_index = try self.allocateAllocSection(.{
-            .name = ".text.zig",
-            .phdr_index = self.phdr_load_re_zig_index.?,
+    if (self.zig_text_section_index == null) {
+        self.zig_text_section_index = try self.allocateAllocSection(.{
+            .name = ".zig.text",
+            .phdr_index = self.phdr_zig_load_re_index.?,
             .flags = elf.SHF_ALLOC | elf.SHF_EXECINSTR,
         });
-        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.text_zig_section_index.?, .{});
+        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.zig_text_section_index.?, .{});
     }
 
-    if (self.got_zig_section_index == null) {
-        self.got_zig_section_index = try self.allocateAllocSection(.{
-            .name = ".got.zig",
-            .phdr_index = self.phdr_got_zig_index.?,
+    if (self.zig_got_section_index == null) {
+        self.zig_got_section_index = try self.allocateAllocSection(.{
+            .name = ".zig.got",
+            .phdr_index = self.phdr_zig_got_index.?,
             .alignment = ptr_size,
         });
     }
 
-    if (self.rodata_zig_section_index == null) {
-        self.rodata_zig_section_index = try self.allocateAllocSection(.{
-            .name = ".rodata.zig",
-            .phdr_index = self.phdr_load_ro_zig_index.?,
+    if (self.zig_rodata_section_index == null) {
+        self.zig_rodata_section_index = try self.allocateAllocSection(.{
+            .name = ".zig.rodata",
+            .phdr_index = self.phdr_zig_load_ro_index.?,
         });
-        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.rodata_zig_section_index.?, .{});
+        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.zig_rodata_section_index.?, .{});
     }
 
-    if (self.data_zig_section_index == null) {
-        self.data_zig_section_index = try self.allocateAllocSection(.{
-            .name = ".data.zig",
-            .phdr_index = self.phdr_load_rw_zig_index.?,
+    if (self.zig_data_section_index == null) {
+        self.zig_data_section_index = try self.allocateAllocSection(.{
+            .name = ".zig.data",
+            .phdr_index = self.phdr_zig_load_rw_index.?,
             .alignment = ptr_size,
             .flags = elf.SHF_ALLOC | elf.SHF_WRITE,
         });
-        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.data_zig_section_index.?, .{});
+        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.zig_data_section_index.?, .{});
     }
 
-    if (self.bss_zig_section_index == null) {
-        self.bss_zig_section_index = try self.allocateAllocSection(.{
+    if (self.zig_bss_section_index == null) {
+        self.zig_bss_section_index = try self.allocateAllocSection(.{
             .name = ".bss.zig",
-            .phdr_index = self.phdr_load_zerofill_zig_index.?,
+            .phdr_index = self.phdr_zig_load_zerofill_index.?,
             .alignment = ptr_size,
             .flags = elf.SHF_ALLOC | elf.SHF_WRITE,
             .type = elf.SHT_NOBITS,
         });
-        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.bss_zig_section_index.?, .{});
+        try self.last_atom_and_free_list_table.putNoClobber(gpa, self.zig_bss_section_index.?, .{});
     }
 
     if (self.dwarf) |*dw| {
@@ -875,7 +877,7 @@ pub fn growAllocSection(self: *Elf, shdr_index: u16, needed_size: u64) !void {
     }
 
     const mem_capacity = self.allocatedVirtualSize(phdr.p_vaddr);
-    if (needed_size <= mem_capacity) {
+    if (needed_size > mem_capacity) {
         var err = try self.addErrorWithNotes(2);
         try err.addMsg(self, "fatal linker error: cannot expand load segment phdr({d}) in virtual memory", .{
             phdr_index,
@@ -1544,8 +1546,8 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
     if (self.zig_module_index) |index| {
         // .bss.zig always overlaps .data.zig in file offset, but is zero-sized in file so it doesn't
         // get mapped by the loader
-        if (self.data_zig_section_index) |data_shndx| blk: {
-            const bss_shndx = self.bss_zig_section_index orelse break :blk;
+        if (self.zig_data_section_index) |data_shndx| blk: {
+            const bss_shndx = self.zig_bss_section_index orelse break :blk;
             const data_phndx = self.phdr_to_shdr_table.get(data_shndx).?;
             const bss_phndx = self.phdr_to_shdr_table.get(bss_shndx).?;
             self.shdrs.items[bss_shndx].sh_offset = self.shdrs.items[data_shndx].sh_offset;
@@ -1580,7 +1582,7 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
             if (self.debug_info_header_dirty) {
                 // Currently only one compilation unit is supported, so the address range is simply
                 // identical to the main program header virtual address and memory size.
-                const text_phdr = &self.phdrs.items[self.phdr_load_re_zig_index.?];
+                const text_phdr = &self.phdrs.items[self.phdr_zig_load_re_index.?];
                 const low_pc = text_phdr.p_vaddr;
                 const high_pc = text_phdr.p_vaddr + text_phdr.p_memsz;
                 try dw.writeDbgInfoHeader(self.base.options.module.?, low_pc, high_pc);
@@ -1590,7 +1592,7 @@ pub fn flushModule(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node
             if (self.debug_aranges_section_dirty) {
                 // Currently only one compilation unit is supported, so the address range is simply
                 // identical to the main program header virtual address and memory size.
-                const text_phdr = &self.phdrs.items[self.phdr_load_re_zig_index.?];
+                const text_phdr = &self.phdrs.items[self.phdr_zig_load_re_index.?];
                 try dw.writeDbgAranges(text_phdr.p_vaddr, text_phdr.p_memsz);
                 self.debug_aranges_section_dirty = false;
             }
@@ -2999,24 +3001,24 @@ fn getDeclShdrIndex(self: *Elf, decl_index: Module.Decl.Index, code: []const u8)
     const decl = mod.declPtr(decl_index);
     const shdr_index = switch (decl.ty.zigTypeTag(mod)) {
         // TODO: what if this is a function pointer?
-        .Fn => self.text_zig_section_index.?,
+        .Fn => self.zig_text_section_index.?,
         else => blk: {
             if (decl.getOwnedVariable(mod)) |variable| {
-                if (variable.is_const) break :blk self.rodata_zig_section_index.?;
+                if (variable.is_const) break :blk self.zig_rodata_section_index.?;
                 if (variable.init.toValue().isUndefDeep(mod)) {
                     const mode = self.base.options.optimize_mode;
-                    if (mode == .Debug or mode == .ReleaseSafe) break :blk self.data_zig_section_index.?;
-                    break :blk self.bss_zig_section_index.?;
+                    if (mode == .Debug or mode == .ReleaseSafe) break :blk self.zig_data_section_index.?;
+                    break :blk self.zig_bss_section_index.?;
                 }
                 // TODO I blatantly copied the logic from the Wasm linker, but is there a less
                 // intrusive check for all zeroes than this?
                 const is_all_zeroes = for (code) |byte| {
                     if (byte != 0) break false;
                 } else true;
-                if (is_all_zeroes) break :blk self.bss_zig_section_index.?;
-                break :blk self.data_zig_section_index.?;
+                if (is_all_zeroes) break :blk self.zig_bss_section_index.?;
+                break :blk self.zig_data_section_index.?;
             }
-            break :blk self.rodata_zig_section_index.?;
+            break :blk self.zig_rodata_section_index.?;
         },
     };
     return shdr_index;
@@ -3070,8 +3072,9 @@ fn updateDeclCode(
                 esym.st_value = atom_ptr.value;
 
                 log.debug("  (writing new offset table entry)", .{});
-                // const extra = sym.extra(self).?;
-                // try self.got.writeEntry(self, extra.got);
+                assert(sym.flags.has_zig_got);
+                const extra = sym.extra(self).?;
+                try self.zig_got.writeOne(self, extra.zig_got);
             }
         } else if (code.len < old_size) {
             atom_ptr.shrink(self);
@@ -3083,10 +3086,8 @@ fn updateDeclCode(
         sym.value = atom_ptr.value;
         esym.st_value = atom_ptr.value;
 
-        sym.flags.needs_got = true;
-        const gop = try sym.getOrCreateGotEntry(sym_index, self);
-        _ = gop;
-        // try self.got.writeEntry(self, gop.index);
+        const gop = try sym.getOrCreateZigGotEntry(sym_index, self);
+        try self.zig_got.writeOne(self, gop.index);
     }
 
     if (self.base.child_pid) |pid| {
@@ -3296,8 +3297,8 @@ fn updateLazySymbol(self: *Elf, sym: link.File.LazySymbol, symbol_index: Symbol.
     };
 
     const output_section_index = switch (sym.kind) {
-        .code => self.text_zig_section_index.?,
-        .const_data => self.rodata_zig_section_index.?,
+        .code => self.zig_text_section_index.?,
+        .const_data => self.zig_rodata_section_index.?,
     };
     const local_sym = self.symbol(symbol_index);
     const phdr_index = self.phdr_to_shdr_table.get(output_section_index).?;
@@ -3320,10 +3321,8 @@ fn updateLazySymbol(self: *Elf, sym: link.File.LazySymbol, symbol_index: Symbol.
     local_sym.value = atom_ptr.value;
     local_esym.st_value = atom_ptr.value;
 
-    local_sym.flags.needs_got = true;
-    const gop = try local_sym.getOrCreateGotEntry(symbol_index, self);
-    _ = gop;
-    // try self.got.writeEntry(self, gop.index);
+    const gop = try local_sym.getOrCreateZigGotEntry(symbol_index, self);
+    try self.zig_got.writeOne(self, gop.index);
 
     const section_offset = atom_ptr.value - self.phdrs.items[phdr_index].p_vaddr;
     const file_offset = self.shdrs.items[output_section_index].sh_offset + section_offset;
@@ -3343,7 +3342,7 @@ pub fn lowerUnnamedConst(self: *Elf, typed_value: TypedValue, decl_index: Module
     const index = unnamed_consts.items.len;
     const name = try std.fmt.allocPrint(gpa, "__unnamed_{s}_{d}", .{ decl_name, index });
     defer gpa.free(name);
-    const sym_index = switch (try self.lowerConst(name, typed_value, self.rodata_zig_section_index.?, decl.srcLoc(mod))) {
+    const sym_index = switch (try self.lowerConst(name, typed_value, self.zig_rodata_section_index.?, decl.srcLoc(mod))) {
         .ok => |sym_index| sym_index,
         .fail => |em| {
             decl.analysis = .codegen_failure;
@@ -4183,11 +4182,11 @@ fn sortSections(self: *Elf) !void {
         &self.copy_rel_section_index,
         &self.versym_section_index,
         &self.verneed_section_index,
-        &self.text_zig_section_index,
-        &self.got_zig_section_index,
-        &self.rodata_zig_section_index,
-        &self.data_zig_section_index,
-        &self.bss_zig_section_index,
+        &self.zig_text_section_index,
+        &self.zig_got_section_index,
+        &self.zig_rodata_section_index,
+        &self.zig_data_section_index,
+        &self.zig_bss_section_index,
         &self.debug_str_section_index,
         &self.debug_info_section_index,
         &self.debug_abbrev_section_index,
@@ -4340,6 +4339,9 @@ fn updateSectionSizes(self: *Elf) !void {
     if (self.strtab_section_index) |index| {
         // TODO I don't really this here but we need it to add symbol names from GOT and other synthetic
         // sections into .strtab for easier debugging.
+        if (self.zig_got_section_index) |_| {
+            try self.zig_got.updateStrtab(self);
+        }
         if (self.got_section_index) |_| {
             try self.got.updateStrtab(self);
         }
@@ -4719,6 +4721,11 @@ fn updateSymtabSize(self: *Elf) !void {
         sizes.nglobals += shared_object.output_symtab_size.nglobals;
     }
 
+    if (self.zig_got_section_index) |_| {
+        self.zig_got.updateSymtabSize(self);
+        sizes.nlocals += self.zig_got.output_symtab_size.nlocals;
+    }
+
     if (self.got_section_index) |_| {
         self.got.updateSymtabSize(self);
         sizes.nlocals += self.got.output_symtab_size.nlocals;
@@ -4930,6 +4937,11 @@ fn writeSymtab(self: *Elf) !void {
         ctx.iglobal += shared_object.output_symtab_size.nglobals;
     }
 
+    if (self.zig_got_section_index) |_| {
+        try self.zig_got.writeSymtab(self, ctx);
+        ctx.ilocal += self.zig_got.output_symtab_size.nlocals;
+    }
+
     if (self.got_section_index) |_| {
         try self.got.writeSymtab(self, ctx);
         ctx.ilocal += self.got.output_symtab_size.nlocals;
@@ -5289,11 +5301,11 @@ pub fn isDynLib(self: Elf) bool {
 
 pub fn isZigSection(self: Elf, shndx: u16) bool {
     inline for (&[_]?u16{
-        self.text_zig_section_index,
-        self.rodata_zig_section_index,
-        self.data_zig_section_index,
-        self.bss_zig_section_index,
-        self.got_zig_section_index,
+        self.zig_text_section_index,
+        self.zig_rodata_section_index,
+        self.zig_data_section_index,
+        self.zig_bss_section_index,
+        self.zig_got_section_index,
     }) |maybe_index| {
         if (maybe_index) |index| {
             if (index == shndx) return true;
@@ -5851,6 +5863,7 @@ fn fmtDumpState(
         try writer.print("{}\n", .{linker_defined.fmtSymtab(self)});
     }
     try writer.print("{}\n", .{self.got.fmt(self)});
+    try writer.print("{}\n", .{self.zig_got.fmt(self)});
     try writer.writeAll("Output shdrs\n");
     for (self.shdrs.items, 0..) |shdr, shndx| {
         try writer.print("shdr({d}) : phdr({?d}) : {}\n", .{
@@ -6030,4 +6043,5 @@ const Type = @import("../type.zig").Type;
 const TypedValue = @import("../TypedValue.zig");
 const Value = @import("../value.zig").Value;
 const VerneedSection = synthetic_sections.VerneedSection;
+const ZigGotSection = synthetic_sections.ZigGotSection;
 const ZigModule = @import("Elf/ZigModule.zig");
src/codegen.zig
@@ -889,9 +889,8 @@ fn genDeclRef(
     if (bin_file.cast(link.File.Elf)) |elf_file| {
         const sym_index = try elf_file.getOrCreateMetadataForDecl(decl_index);
         const sym = elf_file.symbol(sym_index);
-        sym.flags.needs_got = true;
-        _ = try sym.getOrCreateGotEntry(sym_index, elf_file);
-        return GenResult.mcv(.{ .memory = sym.gotAddress(elf_file) });
+        _ = try sym.getOrCreateZigGotEntry(sym_index, elf_file);
+        return GenResult.mcv(.{ .memory = sym.zigGotAddress(elf_file) });
     } else if (bin_file.cast(link.File.MachO)) |macho_file| {
         const atom_index = try macho_file.getOrCreateAtomForDecl(decl_index);
         const sym_index = macho_file.getAtom(atom_index).getSymbolIndex().?;