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Recommit "[llvm-objcopy][MachO] Implement a layout algorithm for executables"

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Summary: The layout algorithm for relocatable objects and for executable are somewhat different. This patch implements the latter one based on the algorithm in LLD (MachOFileLayout).

Reviewers: alexshap, rupprecht, jhenderson

Reviewed By: alexshap

Subscribers: jakehehrlich, abrachet, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65539

llvm-svn: 369301
This commit is contained in:
Seiya Nuta 2019-08-19 21:12:02 +00:00
parent fddd9d319f
commit aba5322f2a
2 changed files with 338 additions and 21 deletions
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291
test/tools/llvm-objcopy/MachO/basic-executable-copy.test Normal file
View File

@ -0,0 +1,291 @@
## This test verifies that llvm-objcopy copies an executable properly. It
## uses llvm-readobj instead of cmp because some parts of the object
## (e.g., the string table) are not identical; the output file is correct but
## some offsets differ from the input file.
# RUN: yaml2obj %s > %t
# RUN: llvm-objcopy %t %t2
# RUN: llvm-readobj --file-headers --sections %t2 | FileCheck %s
--- !mach-o
FileHeader:
magic: 0xFEEDFACF
cputype: 0x01000007
cpusubtype: 0x80000003
filetype: 0x00000002
ncmds: 15
sizeofcmds: 976
flags: 0x00200085
reserved: 0x00000000
LoadCommands:
- cmd: LC_SEGMENT_64
cmdsize: 72
segname: __PAGEZERO
vmaddr: 0
vmsize: 4294967296
fileoff: 0
filesize: 0
maxprot: 0
initprot: 0
nsects: 0
flags: 0
- cmd: LC_SEGMENT_64
cmdsize: 232
segname: __TEXT
vmaddr: 4294967296
vmsize: 4096
fileoff: 0
filesize: 4096
maxprot: 7
initprot: 5
nsects: 2
flags: 0
Sections:
- sectname: __text
segname: __TEXT
addr: 0x0000000100000F70
size: 58
offset: 0x00000F70
align: 4
reloff: 0x00000000
nreloc: 0
flags: 0x80000400
reserved1: 0x00000000
reserved2: 0x00000000
reserved3: 0x00000000
- sectname: __unwind_info
segname: __TEXT
addr: 0x0000000100000FAC
size: 72
offset: 0x00000FAC
align: 2
reloff: 0x00000000
nreloc: 0
flags: 0x00000000
reserved1: 0x00000000
reserved2: 0x00000000
reserved3: 0x00000000
- cmd: LC_SEGMENT_64
cmdsize: 232
segname: __DATA
vmaddr: 4294971392
vmsize: 4096
fileoff: 4096
filesize: 4096
maxprot: 7
initprot: 3
nsects: 2
flags: 0
Sections:
- sectname: __data
segname: __DATA
addr: 0x0000000100001000
size: 4
offset: 0x00001000
align: 2
reloff: 0x00000000
nreloc: 0
flags: 0x00000000
reserved1: 0x00000000
reserved2: 0x00000000
reserved3: 0x00000000
- sectname: __common
segname: __DATA
addr: 0x0000000100001004
size: 4
offset: 0x00000000
align: 2
reloff: 0x00000000
nreloc: 0
flags: 0x00000001
reserved1: 0x00000000
reserved2: 0x00000000
reserved3: 0x00000000
- cmd: LC_SEGMENT_64
cmdsize: 72
segname: __LINKEDIT
vmaddr: 4294975488
vmsize: 4096
fileoff: 8192
filesize: 232
maxprot: 7
initprot: 1
nsects: 0
flags: 0
- cmd: LC_DYLD_INFO_ONLY
cmdsize: 48
rebase_off: 0
rebase_size: 0
bind_off: 0
bind_size: 0
weak_bind_off: 0
weak_bind_size: 0
lazy_bind_off: 0
lazy_bind_size: 0
export_off: 8192
export_size: 72
- cmd: LC_SYMTAB
cmdsize: 24
symoff: 8272
nsyms: 6
stroff: 8368
strsize: 56
- cmd: LC_DYSYMTAB
cmdsize: 80
ilocalsym: 0
nlocalsym: 0
iextdefsym: 0
nextdefsym: 5
iundefsym: 5
nundefsym: 1
tocoff: 0
ntoc: 0
modtaboff: 0
nmodtab: 0
extrefsymoff: 0
nextrefsyms: 0
indirectsymoff: 0
nindirectsyms: 0
extreloff: 0
nextrel: 0
locreloff: 0
nlocrel: 0
- cmd: LC_LOAD_DYLINKER
cmdsize: 32
name: 12
PayloadString: '/usr/lib/dyld'
ZeroPadBytes: 7
- cmd: LC_UUID
cmdsize: 24
uuid: B6EE4FB7-4E1E-3C7A-80D3-CFBD89DBC0FE
- cmd: LC_BUILD_VERSION
cmdsize: 32
platform: 1
minos: 658944
sdk: 658944
ntools: 1
Tools:
- tool: 3
version: 29491968
- cmd: LC_SOURCE_VERSION
cmdsize: 16
version: 0
- cmd: LC_MAIN
cmdsize: 24
entryoff: 3984
stacksize: 0
- cmd: LC_LOAD_DYLIB
cmdsize: 56
dylib:
name: 24
timestamp: 2
current_version: 82115073
compatibility_version: 65536
PayloadString: '/usr/lib/libSystem.B.dylib'
ZeroPadBytes: 6
- cmd: LC_FUNCTION_STARTS
cmdsize: 16
dataoff: 8264
datasize: 8
- cmd: LC_DATA_IN_CODE
cmdsize: 16
dataoff: 8272
datasize: 0
LinkEditData:
ExportTrie:
TerminalSize: 0
NodeOffset: 0
Name: ''
Flags: 0x0000000000000000
Address: 0x0000000000000000
Other: 0x0000000000000000
ImportName: ''
Children:
- TerminalSize: 0
NodeOffset: 5
Name: _
Flags: 0x0000000000000000
Address: 0x0000000000000000
Other: 0x0000000000000000
ImportName: ''
Children:
- TerminalSize: 2
NodeOffset: 44
Name: _mh_execute_header
Flags: 0x0000000000000000
Address: 0x0000000000000000
Other: 0x0000000000000000
ImportName: ''
- TerminalSize: 3
NodeOffset: 48
Name: foo
Flags: 0x0000000000000000
Address: 0x0000000000000F70
Other: 0x0000000000000000
ImportName: ''
- TerminalSize: 3
NodeOffset: 53
Name: main
Flags: 0x0000000000000000
Address: 0x0000000000000F90
Other: 0x0000000000000000
ImportName: ''
- TerminalSize: 3
NodeOffset: 58
Name: b
Flags: 0x0000000000000000
Address: 0x0000000000001000
Other: 0x0000000000000000
ImportName: ''
- TerminalSize: 3
NodeOffset: 63
Name: a
Flags: 0x0000000000000000
Address: 0x0000000000001004
Other: 0x0000000000000000
ImportName: ''
NameList:
- n_strx: 2
n_type: 0x0F
n_sect: 1
n_desc: 16
n_value: 4294967296
- n_strx: 22
n_type: 0x0F
n_sect: 4
n_desc: 0
n_value: 4294971396
- n_strx: 25
n_type: 0x0F
n_sect: 3
n_desc: 0
n_value: 4294971392
- n_strx: 28
n_type: 0x0F
n_sect: 1
n_desc: 0
n_value: 4294971248
- n_strx: 33
n_type: 0x0F
n_sect: 1
n_desc: 0
n_value: 4294971280
- n_strx: 39
n_type: 0x01
n_sect: 0
n_desc: 256
n_value: 0
StringTable:
- ' '
- __mh_execute_header
- _a
- _b
- _foo
- _main
- dyld_stub_binder
...
# CHECK: FileType: Executable (0x2)
# CHECK: Name: __text
# CHECK: Name: __unwind_info
# CHECK: Name: __data
# CHECK: Name: __common

68
tools/llvm-objcopy/MachO/MachOLayoutBuilder.cpp
View File

@ -17,7 +17,7 @@ namespace macho {
uint32_t MachOLayoutBuilder::computeSizeOfCmds() const {
uint32_t Size = 0;
for (const auto &LC : O.LoadCommands) {
auto &MLC = LC.MachOLoadCommand;
const MachO::macho_load_command &MLC = LC.MachOLoadCommand;
auto cmd = MLC.load_command_data.cmd;
switch (cmd) {
case MachO::LC_SEGMENT:
@ -101,20 +101,25 @@ void MachOLayoutBuilder::updateDySymTab(MachO::macho_load_command &MLC) {
uint64_t MachOLayoutBuilder::layoutSegments() {
auto HeaderSize =
Is64Bit ? sizeof(MachO::mach_header_64) : sizeof(MachO::mach_header);
auto Offset = HeaderSize + O.Header.SizeOfCmds;
// Lay out sections.
const bool IsObjectFile =
O.Header.FileType == MachO::HeaderFileType::MH_OBJECT;
uint64_t Offset = IsObjectFile ? (HeaderSize + O.Header.SizeOfCmds) : 0;
for (auto &LC : O.LoadCommands) {
uint64_t FileOff = Offset;
auto &MLC = LC.MachOLoadCommand;
StringRef Segname;
uint64_t SegmentVmAddr;
uint64_t SegmentVmSize;
switch (MLC.load_command_data.cmd) {
case MachO::LC_SEGMENT:
SegmentVmAddr = MLC.segment_command_data.vmaddr;
SegmentVmSize = MLC.segment_command_data.vmsize;
Segname = StringRef(MLC.segment_command_data.segname,
strnlen(MLC.segment_command_data.segname,
sizeof(MLC.segment_command_data.segname)));
break;
case MachO::LC_SEGMENT_64:
SegmentVmAddr = MLC.segment_command_64_data.vmaddr;
SegmentVmSize = MLC.segment_command_64_data.vmsize;
Segname = StringRef(MLC.segment_command_64_data.segname,
strnlen(MLC.segment_command_64_data.segname,
sizeof(MLC.segment_command_64_data.segname)));
@ -131,43 +136,64 @@ uint64_t MachOLayoutBuilder::layoutSegments() {
}
// Update file offsets and sizes of sections.
uint64_t SegOffset = Offset;
uint64_t SegFileSize = 0;
uint64_t VMSize = 0;
uint64_t FileOffsetInSegment = 0;
for (auto &Sec : LC.Sections) {
if (!Sec.isVirtualSection()) {
auto FilePaddingSize =
OffsetToAlignment(FileOffsetInSegment, 1ull << Sec.Align);
Sec.Offset = Offset + FileOffsetInSegment + FilePaddingSize;
Sec.Size = Sec.Content.size();
FileOffsetInSegment += FilePaddingSize + Sec.Size;
if (IsObjectFile) {
if (Sec.isVirtualSection()) {
Sec.Offset = 0;
} else {
uint64_t PaddingSize = OffsetToAlignment(SegFileSize, 1 << Sec.Align);
Sec.Offset = SegOffset + SegFileSize + PaddingSize;
Sec.Size = Sec.Content.size();
SegFileSize += PaddingSize + Sec.Size;
}
VMSize = std::max(VMSize, Sec.Addr + Sec.Size);
} else {
if (Sec.isVirtualSection()) {
Sec.Offset = 0;
VMSize += Sec.Size;
} else {
uint32_t SectOffset = Sec.Addr - SegmentVmAddr;
Sec.Offset = SegOffset + SectOffset;
Sec.Size = Sec.Content.size();
SegFileSize = std::max(SegFileSize, SectOffset + Sec.Size);
VMSize = std::max(VMSize, SegFileSize);
}
}
VMSize = std::max(VMSize, Sec.Addr + Sec.Size);
}
// TODO: Handle the __PAGEZERO segment.
if (IsObjectFile) {
Offset += SegFileSize;
} else {
Offset = alignTo(Offset + SegFileSize, PageSize);
SegFileSize = alignTo(SegFileSize, PageSize);
// Use the original vmsize if the segment is __PAGEZERO.
VMSize =
Segname == "__PAGEZERO" ? SegmentVmSize : alignTo(VMSize, PageSize);
}
switch (MLC.load_command_data.cmd) {
case MachO::LC_SEGMENT:
MLC.segment_command_data.cmdsize =
sizeof(MachO::segment_command) +
sizeof(MachO::section) * LC.Sections.size();
MLC.segment_command_data.nsects = LC.Sections.size();
MLC.segment_command_data.fileoff = FileOff;
MLC.segment_command_data.fileoff = SegOffset;
MLC.segment_command_data.vmsize = VMSize;
MLC.segment_command_data.filesize = FileOffsetInSegment;
MLC.segment_command_data.filesize = SegFileSize;
break;
case MachO::LC_SEGMENT_64:
MLC.segment_command_64_data.cmdsize =
sizeof(MachO::segment_command_64) +
sizeof(MachO::section_64) * LC.Sections.size();
MLC.segment_command_64_data.nsects = LC.Sections.size();
MLC.segment_command_64_data.fileoff = FileOff;
MLC.segment_command_64_data.fileoff = SegOffset;
MLC.segment_command_64_data.vmsize = VMSize;
MLC.segment_command_64_data.filesize = FileOffsetInSegment;
MLC.segment_command_64_data.filesize = SegFileSize;
break;
}
Offset += FileOffsetInSegment;
}
return Offset;