From 98138ba78c1540830a4fdb0537ed6ad5c7b57e7a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Motiejus=20Jak=C5=A1tys?= Date: Thu, 16 Jun 2022 15:42:35 +0300 Subject: [PATCH] [MachO] add -pagezero_size Pass `-pagezero_size` to the MachO linker. This is the final "unsupported linker arg" that I could chase that CGo uses. After this and #11874 we may be able to fail on an "unsupported linker arg" instead of emiting a warning. Test case: zig=/code/zig/build/zig CGO_ENABLED=1 GOOS=darwin GOARCH=amd64 CC="$zig cc -target x86_64-macos" CXX="$zig c++ -target x86_64-macos" go build -a -ldflags "-s -w" cgo.go I compiled a trivial CGo program and executed it on an amd64 Darwin host. To be honest, I am not entirely sure what this is doing. This feels right after reading what this argument does in LLVM sources, but I am by no means qualified to make MachO pull requests. Will take feedback. --- src/Compilation.zig | 7 +++++-- src/link.zig | 3 +++ src/link/Coff.zig | 2 +- src/link/Elf.zig | 2 +- src/link/MachO.zig | 11 ++++++----- src/link/Wasm.zig | 2 +- src/main.zig | 12 ++++++++++++ 7 files changed, 29 insertions(+), 10 deletions(-) diff --git a/src/Compilation.zig b/src/Compilation.zig index 2646da2f6f..98d69ee78e 100644 --- a/src/Compilation.zig +++ b/src/Compilation.zig @@ -903,6 +903,8 @@ pub const InitOptions = struct { install_name: ?[]const u8 = null, /// (Darwin) Path to entitlements file entitlements: ?[]const u8 = null, + /// (Darwin) size of the __PAGEZERO segment + pagezero_size: ?u64 = null, }; fn addPackageTableToCacheHash( @@ -2359,7 +2361,7 @@ fn prepareWholeEmitSubPath(arena: Allocator, opt_emit: ?EmitLoc) error{OutOfMemo /// to remind the programmer to update multiple related pieces of code that /// are in different locations. Bump this number when adding or deleting /// anything from the link cache manifest. -pub const link_hash_implementation_version = 3; +pub const link_hash_implementation_version = 4; fn addNonIncrementalStuffToCacheManifest(comp: *Compilation, man: *Cache.Manifest) !void { const gpa = comp.gpa; @@ -2369,7 +2371,7 @@ fn addNonIncrementalStuffToCacheManifest(comp: *Compilation, man: *Cache.Manifes defer arena_allocator.deinit(); const arena = arena_allocator.allocator(); - comptime assert(link_hash_implementation_version == 3); + comptime assert(link_hash_implementation_version == 4); if (comp.bin_file.options.module) |mod| { const main_zig_file = try mod.main_pkg.root_src_directory.join(arena, &[_][]const u8{ @@ -2474,6 +2476,7 @@ fn addNonIncrementalStuffToCacheManifest(comp: *Compilation, man: *Cache.Manifes man.hash.addListOfBytes(comp.bin_file.options.framework_dirs); man.hash.addListOfBytes(comp.bin_file.options.frameworks); try man.addOptionalFile(comp.bin_file.options.entitlements); + if (comp.bin_file.options.pagezero_size) |value| man.hash.add(value); // COFF specific stuff man.hash.addOptional(comp.bin_file.options.subsystem); diff --git a/src/link.zig b/src/link.zig index 65e9de8ca3..ad1fc417f3 100644 --- a/src/link.zig +++ b/src/link.zig @@ -187,6 +187,9 @@ pub const Options = struct { /// (Darwin) Path to entitlements file entitlements: ?[]const u8 = null, + /// (Darwin) size of the __PAGEZERO segment + pagezero_size: ?u64 = null, + pub fn effectiveOutputMode(options: Options) std.builtin.OutputMode { return if (options.use_lld) .Obj else options.output_mode; } diff --git a/src/link/Coff.zig b/src/link/Coff.zig index 2943cae36a..6b4ff26bce 100644 --- a/src/link/Coff.zig +++ b/src/link/Coff.zig @@ -969,7 +969,7 @@ fn linkWithLLD(self: *Coff, comp: *Compilation, prog_node: *std.Progress.Node) ! man = comp.cache_parent.obtain(); self.base.releaseLock(); - comptime assert(Compilation.link_hash_implementation_version == 3); + comptime assert(Compilation.link_hash_implementation_version == 4); for (self.base.options.objects) |obj| { _ = try man.addFile(obj.path, null); diff --git a/src/link/Elf.zig b/src/link/Elf.zig index a0e40e5682..0bcde06f33 100644 --- a/src/link/Elf.zig +++ b/src/link/Elf.zig @@ -1298,7 +1298,7 @@ fn linkWithLLD(self: *Elf, comp: *Compilation, prog_node: *std.Progress.Node) !v // We are about to obtain this lock, so here we give other processes a chance first. self.base.releaseLock(); - comptime assert(Compilation.link_hash_implementation_version == 3); + comptime assert(Compilation.link_hash_implementation_version == 4); try man.addOptionalFile(self.base.options.linker_script); try man.addOptionalFile(self.base.options.version_script); diff --git a/src/link/MachO.zig b/src/link/MachO.zig index c71007157a..ef56cbe548 100644 --- a/src/link/MachO.zig +++ b/src/link/MachO.zig @@ -286,8 +286,8 @@ const default_dyld_path: [*:0]const u8 = "/usr/lib/dyld"; const minimum_text_block_size = 64; pub const min_text_capacity = padToIdeal(minimum_text_block_size); -/// Virtual memory offset corresponds to the size of __PAGEZERO segment and start of -/// __TEXT segment. +/// Virtual memory offset corresponds to the size of __PAGEZERO segment and +/// start of __TEXT segment. const pagezero_vmsize: u64 = 0x100000000; pub const Export = struct { @@ -536,7 +536,7 @@ pub fn flushModule(self: *MachO, comp: *Compilation, prog_node: *std.Progress.No // We are about to obtain this lock, so here we give other processes a chance first. self.base.releaseLock(); - comptime assert(Compilation.link_hash_implementation_version == 3); + comptime assert(Compilation.link_hash_implementation_version == 4); for (self.base.options.objects) |obj| { _ = try man.addFile(obj.path, null); @@ -549,6 +549,7 @@ pub fn flushModule(self: *MachO, comp: *Compilation, prog_node: *std.Progress.No // We can skip hashing libc and libc++ components that we are in charge of building from Zig // installation sources because they are always a product of the compiler version + target information. man.hash.add(stack_size); + if (self.base.options.pagezero_size) |value| man.hash.add(value); man.hash.addListOfBytes(self.base.options.lib_dirs); man.hash.addListOfBytes(self.base.options.framework_dirs); man.hash.addListOfBytes(self.base.options.frameworks); @@ -4372,7 +4373,7 @@ fn populateMissingMetadata(self: *MachO) !void { .segment = .{ .inner = .{ .segname = makeStaticString("__PAGEZERO"), - .vmsize = pagezero_vmsize, + .vmsize = self.base.options.pagezero_size orelse pagezero_vmsize, .cmdsize = @sizeOf(macho.segment_command_64), }, }, @@ -4394,7 +4395,7 @@ fn populateMissingMetadata(self: *MachO) !void { .segment = .{ .inner = .{ .segname = makeStaticString("__TEXT"), - .vmaddr = pagezero_vmsize, + .vmaddr = self.base.options.pagezero_size orelse pagezero_vmsize, .vmsize = needed_size, .filesize = needed_size, .maxprot = macho.PROT.READ | macho.PROT.EXEC, diff --git a/src/link/Wasm.zig b/src/link/Wasm.zig index 5a910e188b..cff47ccdf5 100644 --- a/src/link/Wasm.zig +++ b/src/link/Wasm.zig @@ -2274,7 +2274,7 @@ fn linkWithLLD(self: *Wasm, comp: *Compilation, prog_node: *std.Progress.Node) ! // We are about to obtain this lock, so here we give other processes a chance first. self.base.releaseLock(); - comptime assert(Compilation.link_hash_implementation_version == 3); + comptime assert(Compilation.link_hash_implementation_version == 4); for (self.base.options.objects) |obj| { _ = try man.addFile(obj.path, null); diff --git a/src/main.zig b/src/main.zig index cfd802d11c..bfd711fff7 100644 --- a/src/main.zig +++ b/src/main.zig @@ -447,6 +447,7 @@ const usage_build_generic = \\ -F[dir] (Darwin) add search path for frameworks \\ -install_name=[value] (Darwin) add dylib's install name \\ --entitlements [path] (Darwin) add path to entitlements file for embedding in code signature + \\ -pagezero_size [value] (Darwin) size of the __PAGEZERO segment \\ --import-memory (WebAssembly) import memory from the environment \\ --import-table (WebAssembly) import function table from the host environment \\ --export-table (WebAssembly) export function table to the host environment @@ -694,6 +695,7 @@ fn buildOutputType( var install_name: ?[]const u8 = null; var hash_style: link.HashStyle = .both; var entitlements: ?[]const u8 = null; + var pagezero_size: ?u64 = null; // e.g. -m3dnow or -mno-outline-atomics. They correspond to std.Target llvm cpu feature names. // This array is populated by zig cc frontend and then has to be converted to zig-style @@ -1647,6 +1649,15 @@ fn buildOutputType( linker_optimization = std.fmt.parseUnsigned(u8, arg["-O".len..], 10) catch |err| { fatal("unable to parse '{s}': {s}", .{ arg, @errorName(err) }); }; + } else if (mem.eql(u8, arg, "-pagezero_size")) { + i += 1; + if (i >= linker_args.items.len) { + fatal("expected linker arg after '{s}'", .{arg}); + } + const next_arg = linker_args.items[i]; + pagezero_size = std.fmt.parseUnsigned(u64, next_arg, 0) catch |err| { + fatal("unable to parse '{s}': {s}", .{ arg, @errorName(err) }); + }; } else if (mem.eql(u8, arg, "--gc-sections")) { linker_gc_sections = true; } else if (mem.eql(u8, arg, "--no-gc-sections")) { @@ -2763,6 +2774,7 @@ fn buildOutputType( .native_darwin_sdk = native_darwin_sdk, .install_name = install_name, .entitlements = entitlements, + .pagezero_size = pagezero_size, }) catch |err| switch (err) { error.LibCUnavailable => { const target = target_info.target;