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clang-p2996/llvm/test/tools/llvm-objcopy/ELF/only-keep-debug.test
Igor Kudrin 68616584c3 [llvm-objcopy][ELF] Avoid reordering section headers 
As for now, llvm-objcopy sorts section headers according to the offsets
of the sections in the input file. That can corrupt section references
in the dynamic symbol table because it is a loadable section and as such
is not updated by the tool. Even though the section references are not
required for loading the binary correctly, they are still handy for a
user who analyzes the file.

While the patch removes global reordering of section headers, it layouts
the sections in the same way as before, i.e. according to their original
offsets. All that helps the output file to resemble the input better.

Note that the patch removes sorting SHT_GROUP sections to the start of
the list, which was introduced in D62620 in order to ensure that they
come before the group members, along with the corresponding test. The
original issue was caused by the sorting of section headers, so dropping
the sorting also resolves the issue.

Differential Revision: https://reviews.llvm.org/D107653
2021-08-12 17:12:09 +07:00

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# RUN: yaml2obj --docnum=1 %s -o %t1
# RUN: llvm-objcopy --only-keep-debug %t1 %t1.dbg
# RUN: llvm-readelf -S -l -x .note1 -x .note2 -x .debug_abbrev -x .debug_frame -x .debug_info %t1.dbg | FileCheck %s
## Check that SHT_NOTE and .debug* are kept, but others are changed to SHT_NOBITS.
## SHT_NOBITS sections do not occupy space in the output.
# CHECK: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# CHECK: [ 1] .note1 NOTE 0000000000000400 000400 000001 00 A 0 0 1024
# CHECK-NEXT: [ 2] .note2 NOTE 0000000000000401 000401 000001 00 A 0 0 0
# CHECK-NEXT: [ 3] .text NOBITS 0000000000000402 000402 000001 00 AX 0 0 0
# CHECK-NEXT: [ 4] .tdata NOBITS 0000000000001480 000480 000007 00 WAT 0 0 128
# CHECK-NEXT: [ 5] .tbss NOBITS 0000000000001487 000480 000005 00 WAT 0 0 0
# CHECK-NEXT: [ 6] .bss NOBITS 00000000000014a0 000480 00003f 00 WA 0 0 32
## objcopy sets sh_offset to 0x402. We don't do this to keep sh_offset non-decreasing.
# CHECK-NEXT: [ 7] .debug_abbrev PROGBITS 0000000000000000 000480 000001 00 0 0 0
# CHECK-NEXT: [ 8] .debug_frame PROGBITS 0000000000000000 000488 000001 00 0 0 8
# CHECK-NEXT: [ 9] .debug_info PROGBITS 0000000000000000 000489 000001 00 0 0 0
# CHECK-NEXT: [10] .strtab STRTAB 0000000000000000 00048a 000001 00 0 0 1
# CHECK-NEXT: [11] .shstrtab STRTAB 0000000000000000 00048b 000060 00 0 0 1
# CHECK: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# CHECK-NEXT: LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x000402 0x000403 R E 0x1000
# CHECK-NEXT: LOAD 0x000480 0x0000000000001480 0x0000000000001480 0x000000 0x00005f RW 0x1000
# CHECK-NEXT: TLS 0x000480 0x0000000000001480 0x0000000000001480 0x000000 0x00000c RW 0x80
# CHECK-NEXT: NOTE 0x000400 0x0000000000000400 0x0000000000000400 0x000002 0x000002 0x400
## Contents of SHT_NOTE and .debug* are kept.
# CHECK: Hex dump of section '.note1':
# CHECK-NEXT: 0x00000400 01
# CHECK: Hex dump of section '.note2':
# CHECK-NEXT: 0x00000401 02
# CHECK: Hex dump of section '.debug_abbrev':
# CHECK-NEXT: 0x00000000 03
# CHECK: Hex dump of section '.debug_frame':
# CHECK-NEXT: 0x00000000 04
# CHECK: Hex dump of section '.debug_info':
# CHECK-NEXT: 0x00000000 05
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
Sections:
- Name: .note1
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x400
AddressAlign: 0x400
Content: 01
- Name: .note2
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x401
Content: 02
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x402
Content: c3
- Name: .tdata
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_WRITE, SHF_TLS ]
Address: 0x1480 # Ensure Address=0x1000+Offset
AddressAlign: 0x80
# An arbitrary non-zero Size tests that .tdata does not occupy space
# and we can rewrite p_filesz of PT_TLS.
Size: 7
- Name: .tbss
Type: SHT_NOBITS
Flags: [ SHF_ALLOC, SHF_WRITE, SHF_TLS ]
Address: 0x1487 # Ensure Address=0x1000+Offset
Size: 5
- Name: .bss
Type: SHT_NOBITS
Flags: [ SHF_ALLOC, SHF_WRITE ]
Address: 0x14a0 # Ensure Address=0x1000+Offset
AddressAlign: 0x20
# An arbitrary non-zero Size tests that .bss does not occupy space.
Size: 63
- Name: .debug_abbrev
Type: SHT_PROGBITS
Content: 03
- Name: .debug_frame
Type: SHT_PROGBITS
# AddressAlign tests the file offset assignment leaves a gap.
AddressAlign: 0x8
Content: 04
- Name: .debug_info
Type: SHT_PROGBITS
Content: 05
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_R, PF_X ]
Offset: 0
Align: 0x1000
FirstSec: .note1
LastSec: .text
- Type: PT_LOAD
Flags: [ PF_R, PF_W ]
VAddr: 0x1480 # Ensure Offset=VAddr (mod Align) if Offset changes
Align: 0x1000
FirstSec: .tdata
LastSec: .bss
- Type: PT_TLS
Flags: [ PF_R, PF_W ]
VAddr: 0x1480 # Ensure Offset=VAddr (mod Align) if Offset changes
FirstSec: .tdata
LastSec: .tbss
- Type: PT_NOTE
VAddr: 0x400
FirstSec: .note1
LastSec: .note2
...
# RUN: yaml2obj --docnum=2 %s -o %t2
# RUN: llvm-objcopy --only-keep-debug %t2 %t2.dbg
# RUN: llvm-readelf -S -l %t2.dbg | FileCheck --check-prefix=CHECK2 %s
## Only the tail of a segment can be trimmed. .text still occupies space because
## it is followed by .note which is not SHT_NOBITS.
# CHECK2: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# CHECK2: [ 1] .text NOBITS 0000000000000200 000200 000001 00 AX 0 0 512
# CHECK2-NEXT: [ 2] .note NOTE 0000000000000201 000201 000001 00 A 0 0 0
# CHECK2-NEXT: [ 3] .debug_info PROGBITS 0000000000000000 000220 000001 00 0 0 32
# CHECK2-NEXT: [ 4] .strtab STRTAB 0000000000000000 000221 000001 00 0 0 1
# CHECK2-NEXT: [ 5] .shstrtab STRTAB 0000000000000000 000222 00002b 00 0 0 1
## Check that p_offset or p_filesz of PT_PHDR are not modified.
# CHECK2: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# CHECK2-NEXT: PHDR 0x000040 0x0000000000000040 0x0000000000000040 0x0000a8 0x0000a8 R 0x8
# CHECK2-NEXT: LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x000202 0x000202 R E 0x1000
# CHECK2-NEXT: LOAD 0x000000 0x0000000000000202 0x0000000000000202 0x000000 0x00000e RW 0x1
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x200
AddressAlign: 0x200
Content: c3
- Name: .note
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x201
Content: 01
- Name: .debug_info
Type: SHT_PROGBITS
AddressAlign: 0x20
Content: 02
ProgramHeaders:
- Type: PT_PHDR
Flags: [ PF_R ]
Offset: 0x40
VAddr: 0x40
# 3 * sizeof(Elf64_Phdr) = 0xa8
FileSize: 0xa8
MemSize: 0xa8
Align: 8
- Type: PT_LOAD
Flags: [ PF_R, PF_X ]
Offset: 0
Align: 4096
FirstSec: .text
LastSec: .note
- Type: PT_LOAD
Flags: [ PF_R, PF_W ]
Offset: 0x202
VAddr: 0x202
FileSize: 14
MemSize: 14
...
## If .symtab or .strtab has the SHF_ALLOC flag, it will be changed to SHT_NOBITS.
# RUN: yaml2obj --docnum=3 %s -o %t3
# RUN: llvm-objcopy --only-keep-debug %t3 %t3.dbg
# RUN: llvm-readelf -S -l %t3.dbg | FileCheck --check-prefix=CHECK3 %s
# CHECK3: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# CHECK3: [ 1] .dynsym NOBITS 0000000000000000 000040 000018 18 A 2 1 1024
# CHECK3-NEXT: [ 2] .dynstr NOBITS 0000000000000018 000040 000001 00 A 0 0 0
# CHECK3-NEXT: [ 3] .symtab NOBITS 0000000000000019 000040 000018 00 A 4 1 0
# CHECK3-NEXT: [ 4] .strtab NOBITS 0000000000000031 000040 000001 00 A 0 0 0
# CHECK3-NEXT: [ 5] .shstrtab STRTAB 0000000000000000 000040 00002b 00 0 0 1
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
Sections:
- Name: .dynsym
Type: SHT_DYNSYM
Flags: [ SHF_ALLOC ]
Link: .dynstr
AddressAlign: 0x400
- Name: .dynstr
Type: SHT_STRTAB
Flags: [ SHF_ALLOC ]
- Name: .symtab
## TODO: this should be SHT_SYMTAB, but currently llvm-objcopy reports an error:
## error: Symbol table has link index of 4 which is not a string table
Type: SHT_STRTAB
Flags: [ SHF_ALLOC ]
Link: .strtab
- Name: .strtab
Type: SHT_STRTAB
Flags: [ SHF_ALLOC ]
DynamicSymbols: []
Symbols: []
## PT_TLS and .tdata are empty. Test that we set its p_offset to the parent
## segment's p_offset. If we don't rewrite the p_offset of PT_TLS and the deleted
## bytes are large, p_offset can be larger than the file size, and trigger
## validation errors with subsequent tools.
# RUN: yaml2obj --docnum=4 %s -o %t4
# RUN: llvm-objcopy --only-keep-debug %t4 %t4.dbg
# RUN: llvm-readelf -S -l %t4.dbg | FileCheck --check-prefix=CHECK4 %s
# CHECK4: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# CHECK4: [ 1] .text NOBITS 0000000000000200 000200 000001 00 AX 0 0 0
# CHECK4-NEXT: [ 2] .tdata NOBITS 0000000000001240 000240 000000 00 WAT 0 0 64
# CHECK4-NEXT: [ 3] .got NOBITS 0000000000001240 000240 000008 00 WA 0 0 0
# CHECK4: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# CHECK4-NEXT: LOAD 0x000200 0x0000000000000200 0x0000000000000200 0x000000 0x000001 R E 0x1000
# CHECK4-NEXT: LOAD 0x000240 0x0000000000001240 0x0000000000001240 0x000000 0x000008 RW 0x1000
# CHECK4-NEXT: TLS 0x000240 0x0000000000001240 0x0000000000001240 0x000000 0x000000 R 0x40
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
Sections:
- Name: .text
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
Address: 0x200
Size: 1
- Name: .tdata
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_WRITE, SHF_TLS ]
Address: 0x1240 # Ensure Address=0x1000+Offset
AddressAlign: 0x40
- Name: .got
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC, SHF_WRITE ]
Size: 8
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_R, PF_X ]
VAddr: 0x200
Align: 0x1000
FirstSec: .text
LastSec: .text
## Add .got so that the PT_LOAD does not have zero p_memsz. We don't add
## sections to zero-sized segments so zero-sized segments may have strange
## offsets. In practice, the Linux kernel errors when mmapping a p_memsz
## PT_LOAD,so for practical so this assumption can generally be made.
- Type: PT_LOAD
Flags: [ PF_R, PF_W ]
VAddr: 0x1240
Align: 0x1000
FirstSec: .tdata
LastSec: .got
- Type: PT_TLS
Flags: [ PF_R ]
VAddr: 0x1240
FirstSec: .tdata
LastSec: .tdata
## The offset and size fields of segments which contain no section and have no
## parent segment are set to zeros, so that we can decrease the file size. Such
## segments are not useful for debugging.
# RUN: yaml2obj --docnum=5 %s -o %t5
# RUN: llvm-objcopy --only-keep-debug %t5 %t5.dbg
# RUN: llvm-readelf -S -l %t5.dbg | FileCheck --check-prefix=CHECK5 %s
# RUN: llvm-objcopy --strip-sections %t5 %t5s
# RUN: llvm-objcopy --only-keep-debug %t5s %t5s.dbg
# RUN: llvm-readelf -S -l %t5s.dbg | FileCheck --check-prefix=CHECK5S %s
# CHECK5: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# CHECK5: [ 1] .foo NOBITS 0000000000000000 000078 001000 00 A 0 0 0
# CHECK5-NEXT: [ 2] .strtab STRTAB 0000000000000000 000078 000001 00 0 0 1
# CHECK5-NEXT: [ 3] .shstrtab STRTAB 0000000000000000 000079 000018 00 0 0 1
# CHECK5: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# CHECK5-NEXT: NULL 0x000000 0x0000000000000000 0x0000000000000000 0x000078 0x001000 0x1
# CHECK5-EMPTY:
# CHECK5S: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# CHECK5S-NEXT: NULL 0x000000 0x0000000000000000 0x0000000000000000 0x000078 0x001000 0x1
# CHECK5S-EMPTY:
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Sections:
- Name: .foo
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC ]
Size: 0x01000
ProgramHeaders:
- Type: PT_NULL
Flags: []
FileSize: 0x01000
MemSize: 0x01000
## Check that sections are placed correctly in a case when their order in the
## section header table is different from their layout.
# RUN: yaml2obj --docnum=6 %s -o %t6
# RUN: llvm-objcopy --only-keep-debug %t6 %t6.dbg
# RUN: llvm-readelf -S -l %t6.dbg | FileCheck --check-prefix=CHECK6 %s
# CHECK6: [Nr] Name Type Address Off Size ES Flg Lk Inf Al
# CHECK6: [ 1] foo NOBITS 0000000000000008 001000 000008 00 A 0 0 4
# CHECK6-NEXT: [ 2] bar NOBITS 0000000000000000 001000 000008 00 A 0 0 4
# CHECK6-NEXT: [ 3] baz NOTE 0000000000000018 001008 000008 00 A 0 0 0
# CHECK6-NEXT: [ 4] qux NOTE 0000000000000010 001000 000008 00 A 0 0 0
# CHECK6: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
# CHECK6-NEXT: LOAD 0x001000 0x0000000000000000 0x0000000000000000 0x000000 0x000010 R 0x1000
# CHECK6-NEXT: LOAD 0x001000 0x0000000000000010 0x0000000000000010 0x000010 0x000010 R 0x1
# CHECK6-EMPTY:
--- !ELF
FileHeader:
Class: ELFCLASS64
Data: ELFDATA2LSB
Type: ET_DYN
Machine: EM_X86_64
ProgramHeaders:
- Type: PT_LOAD
Flags: [ PF_R ]
Offset: 0x1000
VAddr: 0x0
Align: 0x1000
FileSize: 0x10
MemSize: 0x10
- Type: PT_LOAD
Flags: [ PF_R ]
Offset: 0x1010
VAddr: 0x10
FileSize: 0x10
MemSize: 0x10
Sections:
- Name: bar
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC ]
Address: 0x0
AddressAlign: 0x4
Offset: 0x1000
Content: 0000000000000000
- Name: foo
Type: SHT_PROGBITS
Flags: [ SHF_ALLOC ]
Address: 0x8
AddressAlign: 0x4
Offset: 0x1008
Content: 0000000000000000
- Name: qux
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x10
Offset: 0x1010
Content: 0000000000000000
- Name: baz
Type: SHT_NOTE
Flags: [ SHF_ALLOC ]
Address: 0x18
Offset: 0x1018
Content: 0000000000000000
- Type: SectionHeaderTable
Sections:
## Note: the order of section headers differs from their layout.
- Name: foo
- Name: bar
- Name: baz
- Name: qux
- Name: .shstrtab
- Name: .strtab
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