[Tarantool-patches] [PATCH luajit 2/2] OSX/iOS: Always generate 64 bit non-FAT Mach-O object files.

[Sergey Bronnikov via Tarantool-patches <tarantool-patches@dev.tarantool.org>]

Reported by Sergey Bronnikov.

(cherry picked from commit 7110b935672489afd6ba3eef3e5139d2f3bd05b6)

Previously, LuaJIT generated Mach-O FAT object files for ARM and
ARM64 on macOS. The patch removes support of 32-bit ARM and
FAT object files and now LuaJIT generate Mach-O object files for
ARM64.

Sergey Bronnikov:
* added the description and the trimmed the test for the problem

Part of tarantool/tarantool#10199
---
 src/jit/bcsave.lua                            | 155 ++-------
 ...-865-cross-generation-mach-o-file.test.lua | 294 +++---------------
 2 files changed, 70 insertions(+), 379 deletions(-)

diff --git a/src/jit/bcsave.lua b/src/jit/bcsave.lua
index 26ec29c6..61953c2d 100644
--- a/src/jit/bcsave.lua
+++ b/src/jit/bcsave.lua
@@ -412,24 +412,12 @@ typedef struct
 {
   mach_header; uint32_t reserved;
 } mach_header_64;
-typedef struct {
-  uint32_t cmd, cmdsize;
-  char segname[16];
-  uint32_t vmaddr, vmsize, fileoff, filesize;
-  uint32_t maxprot, initprot, nsects, flags;
-} mach_segment_command;
 typedef struct {
   uint32_t cmd, cmdsize;
   char segname[16];
   uint64_t vmaddr, vmsize, fileoff, filesize;
   uint32_t maxprot, initprot, nsects, flags;
 } mach_segment_command_64;
-typedef struct {
-  char sectname[16], segname[16];
-  uint32_t addr, size;
-  uint32_t offset, align, reloff, nreloc, flags;
-  uint32_t reserved1, reserved2;
-} mach_section;
 typedef struct {
   char sectname[16], segname[16];
   uint64_t addr, size;
@@ -439,133 +427,58 @@ typedef struct {
 typedef struct {
   uint32_t cmd, cmdsize, symoff, nsyms, stroff, strsize;
 } mach_symtab_command;
-typedef struct {
-  int32_t strx;
-  uint8_t type, sect;
-  int16_t desc;
-  uint32_t value;
-} mach_nlist;
 typedef struct {
   int32_t strx;
   uint8_t type, sect;
   uint16_t desc;
   uint64_t value;
 } mach_nlist_64;
-typedef struct
-{
-  int32_t magic, nfat_arch;
-} mach_fat_header;
-typedef struct
-{
-  int32_t cputype, cpusubtype, offset, size, align;
-} mach_fat_arch;
-typedef struct {
-  struct {
-    mach_header hdr;
-    mach_segment_command seg;
-    mach_section sec;
-    mach_symtab_command sym;
-  } arch[1];
-  mach_nlist sym_entry;
-  uint8_t space[4096];
-} mach_obj;
 typedef struct {
-  struct {
-    mach_header_64 hdr;
-    mach_segment_command_64 seg;
-    mach_section_64 sec;
-    mach_symtab_command sym;
-  } arch[1];
+  mach_header_64 hdr;
+  mach_segment_command_64 seg;
+  mach_section_64 sec;
+  mach_symtab_command sym;
   mach_nlist_64 sym_entry;
   uint8_t space[4096];
 } mach_obj_64;
-typedef struct {
-  mach_fat_header fat;
-  mach_fat_arch fat_arch[2];
-  struct {
-    mach_header hdr;
-    mach_segment_command seg;
-    mach_section sec;
-    mach_symtab_command sym;
-  } arch[2];
-  mach_nlist sym_entry;
-  uint8_t space[4096];
-} mach_fat_obj;
-typedef struct {
-  mach_fat_header fat;
-  mach_fat_arch fat_arch[2];
-  struct {
-    mach_header_64 hdr;
-    mach_segment_command_64 seg;
-    mach_section_64 sec;
-    mach_symtab_command sym;
-  } arch[2];
-  mach_nlist_64 sym_entry;
-  uint8_t space[4096];
-} mach_fat_obj_64;
 ]]
   local symname = '_'..LJBC_PREFIX..ctx.modname
-  local isfat, is64, align, mobj = false, false, 4, "mach_obj"
-  if ctx.arch == "x64" then
-    is64, align, mobj = true, 8, "mach_obj_64"
-  elseif ctx.arch == "arm" then
-    isfat, mobj = true, "mach_fat_obj"
-  elseif ctx.arch == "arm64" then
-    is64, align, isfat, mobj = true, 8, true, "mach_fat_obj_64"
-  else
-    check(ctx.arch == "x86", "unsupported architecture for OSX")
+  local cputype, cpusubtype = 0x01000007, 3
+  if ctx.arch ~= "x64" then
+    check(ctx.arch == "arm64", "unsupported architecture for OSX")
+    cputype, cpusubtype = 0x0100000c, 0
   end
   local function aligned(v, a) return bit.band(v+a-1, -a) end
-  local be32 = bit.bswap -- Mach-O FAT is BE, supported archs are LE.
 
   -- Create Mach-O object and fill in header.
-  local o = ffi.new(mobj)
-  local mach_size = aligned(ffi.offsetof(o, "space")+#symname+2, align)
-  local cputype = ({ x86={7}, x64={0x01000007}, arm={7,12}, arm64={0x01000007,0x0100000c} })[ctx.arch]
-  local cpusubtype = ({ x86={3}, x64={3}, arm={3,9}, arm64={3,0} })[ctx.arch]
-  if isfat then
-    o.fat.magic = be32(0xcafebabe)
-    o.fat.nfat_arch = be32(#cpusubtype)
-  end
+  local o = ffi.new("mach_obj_64")
+  local mach_size = aligned(ffi.offsetof(o, "space")+#symname+2, 8)
 
   -- Fill in sections and symbols.
-  for i=0,#cpusubtype-1 do
-    local ofs = 0
-    if isfat then
-      local a = o.fat_arch[i]
-      a.cputype = be32(cputype[i+1])
-      a.cpusubtype = be32(cpusubtype[i+1])
-      -- Subsequent slices overlap each other to share data.
-      ofs = ffi.offsetof(o, "arch") + i*ffi.sizeof(o.arch[0])
-      a.offset = be32(ofs)
-      a.size = be32(mach_size-ofs+#s)
-    end
-    local a = o.arch[i]
-    a.hdr.magic = is64 and 0xfeedfacf or 0xfeedface
-    a.hdr.cputype = cputype[i+1]
-    a.hdr.cpusubtype = cpusubtype[i+1]
-    a.hdr.filetype = 1
-    a.hdr.ncmds = 2
-    a.hdr.sizeofcmds = ffi.sizeof(a.seg)+ffi.sizeof(a.sec)+ffi.sizeof(a.sym)
-    a.seg.cmd = is64 and 0x19 or 0x1
-    a.seg.cmdsize = ffi.sizeof(a.seg)+ffi.sizeof(a.sec)
-    a.seg.vmsize = #s
-    a.seg.fileoff = mach_size-ofs
-    a.seg.filesize = #s
-    a.seg.maxprot = 1
-    a.seg.initprot = 1
-    a.seg.nsects = 1
-    ffi.copy(a.sec.sectname, "__data")
-    ffi.copy(a.sec.segname, "__DATA")
-    a.sec.size = #s
-    a.sec.offset = mach_size-ofs
-    a.sym.cmd = 2
-    a.sym.cmdsize = ffi.sizeof(a.sym)
-    a.sym.symoff = ffi.offsetof(o, "sym_entry")-ofs
-    a.sym.nsyms = 1
-    a.sym.stroff = ffi.offsetof(o, "sym_entry")+ffi.sizeof(o.sym_entry)-ofs
-    a.sym.strsize = aligned(#symname+2, align)
-  end
+  o.hdr.magic = 0xfeedfacf
+  o.hdr.cputype = cputype
+  o.hdr.cpusubtype = cpusubtype
+  o.hdr.filetype = 1
+  o.hdr.ncmds = 2
+  o.hdr.sizeofcmds = ffi.sizeof(o.seg)+ffi.sizeof(o.sec)+ffi.sizeof(o.sym)
+  o.seg.cmd = 0x19
+  o.seg.cmdsize = ffi.sizeof(o.seg)+ffi.sizeof(o.sec)
+  o.seg.vmsize = #s
+  o.seg.fileoff = mach_size
+  o.seg.filesize = #s
+  o.seg.maxprot = 1
+  o.seg.initprot = 1
+  o.seg.nsects = 1
+  ffi.copy(o.sec.sectname, "__data")
+  ffi.copy(o.sec.segname, "__DATA")
+  o.sec.size = #s
+  o.sec.offset = mach_size
+  o.sym.cmd = 2
+  o.sym.cmdsize = ffi.sizeof(o.sym)
+  o.sym.symoff = ffi.offsetof(o, "sym_entry")
+  o.sym.nsyms = 1
+  o.sym.stroff = ffi.offsetof(o, "sym_entry")+ffi.sizeof(o.sym_entry)
+  o.sym.strsize = aligned(#symname+2, 8)
   o.sym_entry.type = 0xf
   o.sym_entry.sect = 1
   o.sym_entry.strx = 1
diff --git a/test/tarantool-tests/lj-865-cross-generation-mach-o-file.test.lua b/test/tarantool-tests/lj-865-cross-generation-mach-o-file.test.lua
index f008f3bd..6a58de95 100644
--- a/test/tarantool-tests/lj-865-cross-generation-mach-o-file.test.lua
+++ b/test/tarantool-tests/lj-865-cross-generation-mach-o-file.test.lua
@@ -3,109 +3,11 @@ local test = tap.test('lj-865-cross-generation-mach-o-file')
 local utils = require('utils')
 local ffi = require('ffi')
 
-test:plan(2)
+test:plan(1)
 
 -- The test creates an object file in Mach-O format with LuaJIT
 -- bytecode and checks the validity of the object file fields.
---
--- The original problem is reproduced with LuaJIT, which is built
--- with enabled AVX512F instructions. The support for AVX512F
--- could be checked in `/proc/cpuinfo` on Linux and
--- `sysctl hw.optional.avx512f` on Mac. AVX512F must be
--- implicitly enabled in a C compiler by passing a CPU codename.
--- Please take a look at the GCC Online Documentation [1] for
--- available CPU codenames. Also, see the Wikipedia for CPUs with
--- AVX-512 support [2].
--- Execute command below to detect the CPU codename:
--- `gcc -march=native -Q --help=target | grep march`.
---
--- 1. https://gcc.gnu.org/onlinedocs/gcc/x86-Options.html
--- 2. https://en.wikipedia.org/wiki/AVX-512#CPUs_with_AVX-512
---
--- Manual steps for reproducing are the following:
---
--- $ CC=gcc TARGET_CFLAGS='skylake-avx512' cmake -S . -B build
--- $ cmake --build build --parallel
--- $ echo > test.lua
--- $ LUA_PATH="src/?.lua;;" luajit -b -o osx -a arm test.lua test.o
--- $ file test.o
--- empty.o: DOS executable (block device driver)
 
--- LuaJIT can generate so called Universal Binary with Lua
--- bytecode. The Universal Binary format is a format for
--- executable files that run natively on hardware platforms with
--- different hardware architectures. This concept is more
--- generally known as a fat binary.
---
--- The format of the Mach-O is described in the document
--- "OS X ABI Mach-O File Format Reference", published by Apple
--- company. The copy of the (now removed) official documentation
--- can be found here [1]. Yet another source of truth is
--- XNU headers, see the definition of C-structures in:
--- [2] (`nlist_64`), [3] (`fat_arch` and `fat_header`).
---
--- There is a good visual representation of Universal Binary
--- in "Mac OS X Internals" book (pages 67-68) [5] and in the [6].
--- Below is the schematic structure of Universal Binary, which
--- includes two executables for PowerPC and Intel i386 (omitted):
---
---   0x0000000 ---------------------------------------
---             |
--- struct      | 0xcafebabe  FAT_MAGIC                 magic
--- fat_header  | -------------------------------------
---             | 0x00000003                            nfat_arch
---             ---------------------------------------
---             | 0x00000012  CPU_TYPE_POWERPC          cputype
---             | -------------------------------------
---             | 0x00000000  CPU_SUBTYPE_POWERPC_ALL   cpusubtype
--- struct      | -------------------------------------
--- fat_arch    | 0x00001000  4096 bytes                offset
---             | -------------------------------------
---             | 0x00004224  16932 bytes               size
---             | -------------------------------------
---             | 0x0000000c  2^12 = 4096 bytes         align
---             ---------------------------------------
---             ---------------------------------------
---             | 0x00000007  CPU_TYPE_I386             cputype
---             | -------------------------------------
---             | 0x00000003  CPU_SUBTYPE_I386_ALL      cpusubtype
--- struct      | -------------------------------------
--- fat_arch    | 0x00006000  24576 bytes               offset
---             | -------------------------------------
---             | 0x0000292c  10540 bytes               size
---             | -------------------------------------
---             | 0x0000000c  2^12 = 4096 bytes         align
---             ---------------------------------------
---               Unused
--- 0x00001000  ---------------------------------------
---             | 0xfeedface  MH_MAGIC                  magic
---             | ------------------------------------
---             | 0x00000012  CPU_TYPE_POWERPC          cputype
---             | ------------------------------------
--- struct      | 0x00000000  CPU_SUBTYPE_POWERPC_ALL   cpusubtype
--- mach_header | ------------------------------------
---             | 0x00000002  MH_EXECUTE                filetype
---             | ------------------------------------
---             | 0x0000000b  10 load commands          ncmds
---             | ------------------------------------
---             | 0x00000574  1396 bytes                sizeofcmds
---             | ------------------------------------
---             | 0x00000085  DYLDLINK TWOLEVEL         flags
---             --------------------------------------
---               Load commands
---             ---------------------------------------
---               Data
---             ---------------------------------------
---
---               < x86 executable >
---
--- 1. https://github.com/aidansteele/osx-abi-macho-file-format-reference
--- 2. https://github.com/apple-oss-distributions/xnu/blob/xnu-10002.1.13/EXTERNAL_HEADERS/mach-o/nlist.h
--- 3. https://github.com/apple-oss-distributions/xnu/blob/xnu-10002.1.13/EXTERNAL_HEADERS/mach-o/fat.h
--- 4. https://developer.apple.com/documentation/apple-silicon/addressing-architectural-differences-in-your-macos-code
--- 5. https://reverseengineering.stackexchange.com/a/6357/46029
--- 6. http://formats.kaitai.io/mach_o/index.html
---
 -- Using the same declarations as defined in <src/jit/bcsave.lua>.
 ffi.cdef[[
 typedef struct
@@ -118,13 +20,6 @@ typedef struct
   mach_header; uint32_t reserved;
 } mach_header_64;
 
-typedef struct {
-  uint32_t cmd, cmdsize;
-  char segname[16];
-  uint32_t vmaddr, vmsize, fileoff, filesize;
-  uint32_t maxprot, initprot, nsects, flags;
-} mach_segment_command;
-
 typedef struct {
   uint32_t cmd, cmdsize;
   char segname[16];
@@ -132,13 +27,6 @@ typedef struct {
   uint32_t maxprot, initprot, nsects, flags;
 } mach_segment_command_64;
 
-typedef struct {
-  char sectname[16], segname[16];
-  uint32_t addr, size;
-  uint32_t offset, align, reloff, nreloc, flags;
-  uint32_t reserved1, reserved2;
-} mach_section;
-
 typedef struct {
   char sectname[16], segname[16];
   uint64_t addr, size;
@@ -150,13 +38,6 @@ typedef struct {
   uint32_t cmd, cmdsize, symoff, nsyms, stroff, strsize;
 } mach_symtab_command;
 
-typedef struct {
-  int32_t strx;
-  uint8_t type, sect;
-  int16_t desc;
-  uint32_t value;
-} mach_nlist;
-
 typedef struct {
   int32_t strx;
   uint8_t type, sect;
@@ -164,41 +45,14 @@ typedef struct {
   uint64_t value;
 } mach_nlist_64;
 
-typedef struct
-{
-  int32_t magic, nfat_arch;
-} mach_fat_header;
-
-typedef struct
-{
-  int32_t cputype, cpusubtype, offset, size, align;
-} mach_fat_arch;
-
-typedef struct {
-  mach_fat_header fat;
-  mach_fat_arch fat_arch[2];
-  struct {
-    mach_header hdr;
-    mach_segment_command seg;
-    mach_section sec;
-    mach_symtab_command sym;
-  } arch[2];
-  mach_nlist sym_entry;
-  uint8_t space[4096];
-} mach_fat_obj;
-
 typedef struct {
-  mach_fat_header fat;
-  mach_fat_arch fat_arch[2];
-  struct {
-    mach_header_64 hdr;
-    mach_segment_command_64 seg;
-    mach_section_64 sec;
-    mach_symtab_command sym;
-  } arch[2];
+  mach_header_64 hdr;
+  mach_segment_command_64 seg;
+  mach_section_64 sec;
+  mach_symtab_command sym;
   mach_nlist_64 sym_entry;
   uint8_t space[4096];
-} mach_fat_obj_64;
+} mach_obj_64;
 ]]
 
 local function create_obj_file(name, arch)
@@ -212,108 +66,37 @@ local function create_obj_file(name, arch)
   return mach_o_path
 end
 
--- Parses a buffer in the Mach-O format and returns the FAT magic
--- number and `nfat_arch`.
+-- Parses a buffer in the Mach-O format and returns its fields
+-- in a table.
 local function read_mach_o(buf, hw_arch)
-  local res = {
-    header = {
-      magic = 0,
-      nfat_arch = 0,
-    },
-    fat_arch = {},
-  }
-
   local is64 = hw_arch == 'arm64'
 
-  -- Mach-O FAT object.
-  local mach_fat_obj_type = ffi.typeof(is64 and
-                                       'mach_fat_obj_64 *' or
-                                       'mach_fat_obj *')
-  local obj = ffi.cast(mach_fat_obj_type, buf)
+  -- Mach-O object.
+  local mach_obj_type = ffi.typeof(is64 and 'mach_obj_64 *')
+  local obj = ffi.cast(mach_obj_type, buf)
 
-  -- Mach-O FAT object header.
-  local mach_fat_header = obj.fat
-  -- Mach-O FAT is BE, target arch is LE.
-  local be32 = bit.bswap
-  res.header.magic = be32(mach_fat_header.magic)
-  res.header.nfat_arch = be32(mach_fat_header.nfat_arch)
+  -- Mach-O object header.
+  local mach_header = obj.hdr
 
-  -- Mach-O FAT object arches.
-  for i = 0, res.header.nfat_arch - 1 do
-    local fat_arch = obj.fat_arch[i]
-    local arch = {
-      cputype = be32(fat_arch.cputype),
-      cpusubtype = be32(fat_arch.cpusubtype),
-    }
-    table.insert(res.fat_arch, arch)
-  end
-
-  return res
+  return {
+    header = {
+      magic = mach_header.magic,
+      cputype = mach_header.cputype,
+      cpusubtype = mach_header.cpusubtype,
+      filetype = mach_header.filetype,
+      ncmds = mach_header.ncmds,
+    },
+  }
 end
 
--- Universal Binary can contain executables for more than one
--- CPU architecture. For simplicity, the test compares the *sum*
--- of CPU types and CPU subtypes.
---
--- <src/jit/bcsave.lua:bcsave_machobj> has the definitions of the
--- numbers below. The original XNU source code may be found in
--- <osfmk/mach/machine.h> [1].
---
--- 1. https://opensource.apple.com/source/xnu/xnu-4570.41.2/osfmk/mach/machine.h.auto.html
---
-local SUM_CPUTYPE = {
-  -- x86 + arm.
-  arm = 7 + 12,
-  -- x64 + arm64.
-  arm64 = 0x01000007 + 0x0100000c,
-}
-local SUM_CPUSUBTYPE = {
-  -- x86 + arm.
-  arm = 3 + 9,
-  -- x64 + arm64.
-  arm64 = 3 + 0,
-}
-
--- The function builds Mach-O FAT object file and retrieves
--- its header fields (magic and nfat_arch) and fields of each arch
--- (cputype, cpusubtype).
---
--- The Mach-O FAT object header can be retrieved with `otool` on
--- macOS:
---
--- $ otool -f empty.o
--- Fat headers
--- fat_magic 0xcafebabe
--- nfat_arch 2
--- <snipped>
---
--- CPU type and subtype can be retrieved with `lipo` on macOS:
---
--- $ luajit -b -o osx -a arm empty.lua empty.o
--- $ lipo -archs empty.o
--- i386 armv7
--- $ luajit -b -o osx -a arm64 empty.lua empty.o
--- $ lipo -archs empty.o
--- x86_64 arm64
+-- The function builds Mach-O object file and retrieves
+-- its header fields.
 local function build_and_check_mach_o(subtest)
   local hw_arch = subtest.name
-  assert(hw_arch == 'arm' or hw_arch == 'arm64')
+  -- LuaJIT always generate 64-bit non-FAT Mach-O object files.
+  assert(hw_arch == 'arm64')
 
-  subtest:plan(4)
-  -- FAT_MAGIC is an integer containing the value 0xCAFEBABE in
-  -- big-endian byte order format. On a big-endian host CPU,
-  -- this can be validated using the constant FAT_MAGIC;
-  -- on a little-endian host CPU, it can be validated using
-  -- the constant FAT_CIGAM.
-  --
-  -- FAT_NARCH is an integer specifying the number of fat_arch
-  -- data structures that follow. This is the number of
-  -- architectures contained in this binary.
-  --
-  -- See the aforementioned "OS X ABI Mach-O File Format
-  -- Reference".
-  local FAT_MAGIC = '0xffffffffcafebabe'
-  local FAT_NARCH = 2
+  subtest:plan(5)
 
   local MODULE_NAME = 'lango_team'
 
@@ -327,24 +110,19 @@ local function build_and_check_mach_o(subtest)
   assert(os.remove(mach_o_obj_path), 'remove an object file')
 
   local magic_str = string.format('%#x', mach_o.header.magic)
-  subtest:is(magic_str, FAT_MAGIC,
-             'fat_magic is correct in Mach-O')
-  subtest:is(mach_o.header.nfat_arch, FAT_NARCH,
-             'nfat_arch is correct in Mach-O')
-
-  local total_cputype = 0
-  local total_cpusubtype = 0
-  for i = 1, FAT_NARCH do
-    total_cputype = total_cputype + mach_o.fat_arch[i].cputype
-    total_cpusubtype = total_cpusubtype + mach_o.fat_arch[i].cpusubtype
-  end
-  subtest:is(total_cputype, SUM_CPUTYPE[hw_arch],
+  subtest:is(magic_str, '0xfeedfacf',
+             'magic is correct in Mach-O')
+  local cputype_str = string.format('%#x', mach_o.header.cputype)
+  subtest:is(cputype_str, '0x100000c',
              'cputype is correct in Mach-O')
-  subtest:is(total_cpusubtype, SUM_CPUSUBTYPE[hw_arch],
+  subtest:is(mach_o.header.cpusubtype, 0,
              'cpusubtype is correct in Mach-O')
+  subtest:is(mach_o.header.filetype, 1,
+             'filetype is correct in Mach-O')
+  subtest:is(mach_o.header.ncmds, 2,
+             'ncmds is correct in Mach-O')
 end
 
-test:test('arm', build_and_check_mach_o)
 test:test('arm64', build_and_check_mach_o)
 
 test:done(true)
-- 
2.34.1