[PATCH] D68462: [llvm-readobj/llvm-readelf] - Add checks for GNU-style to "all.test" test case.
James Henderson via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Oct 8 01:45:04 PDT 2019
jhenderson added inline comments.
================
Comment at: test/tools/llvm-readobj/all.test:86-90
+ - Name: .eh_frame_hdr
+ Type: SHT_PROGBITS
+## An arbitrary linker-generated valid content.
+ Content: 011b033b140000000100000000f0ffff30000000
+ - Name: .eh_frame
----------------
grimar wrote:
> grimar wrote:
> > jhenderson wrote:
> > > grimar wrote:
> > > > jhenderson wrote:
> > > > > grimar wrote:
> > > > > > jhenderson wrote:
> > > > > > > Same comments as earlier. Can these be empty?
> > > > > > No. We need to have something valid here, otherwise any
> > > > > > error triggered will fail the dumping.
> > > > > > (e.g. https://github.com/llvm-mirror/llvm/blob/master/tools/llvm-readobj/DwarfCFIEHPrinter.h#L127).
> > > > > You don't actually need the .eh_frame_hdr at all, looking at the code, I think, just the .eh_frame section. That said, this appears to be different from GNU readelf.
> > > > >
> > > > > For reference, GNU readelf prints "There are no unwind sections in this file" if there are no .eh_frame_hdr sections even if there is a .eh_frame section (not looked to see what happens if there is a PT_GNU_EH_FRAME program header).
> > > > I am a bit confused.
> > > >
> > > > Imagine we have the code and invocations below:
> > > >
> > > > "1.s":
> > > > ```
> > > > .section foo,"ax", at progbits
> > > > .cfi_startproc
> > > > nop
> > > > .cfi_endproc
> > > > ```
> > > >
> > > > ```
> > > > as 1.s -o 1.o
> > > > ld.bfd 1.o -o with_hdr --eh-frame-hdr
> > > > ld.bfd 1.o -o wo_hdr
> > > > ```
> > > >
> > > > For both of them I do not see neither `.eh_frame_hdr` nor `.eh_frame` section dumped with `-a`.
> > > > I see ".eh_frame" dumped when I add `-wf` though (but still no `.eh_frame_hdr`).
> > > > e.g.:
> > > >
> > > >
> > > > ```
> > > > umb at ubuntu:~/tests/81$ readelf -v
> > > > GNU readelf (GNU Binutils for Ubuntu) 2.31.1
> > > > Copyright (C) 2018 Free Software Foundation, Inc.
> > > >
> > > > umb at ubuntu:~/tests/81$ readelf -a with_hdr
> > > > ELF Header:
> > > > Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
> > > > Class: ELF64
> > > > Data: 2's complement, little endian
> > > > Version: 1 (current)
> > > > OS/ABI: UNIX - System V
> > > > ABI Version: 0
> > > > Type: EXEC (Executable file)
> > > > Machine: Advanced Micro Devices X86-64
> > > > Version: 0x1
> > > > Entry point address: 0x401000
> > > > Start of program headers: 64 (bytes into file)
> > > > Start of section headers: 8584 (bytes into file)
> > > > Flags: 0x0
> > > > Size of this header: 64 (bytes)
> > > > Size of program headers: 56 (bytes)
> > > > Number of program headers: 3
> > > > Size of section headers: 64 (bytes)
> > > > Number of section headers: 7
> > > > Section header string table index: 6
> > > >
> > > > Section Headers:
> > > > [Nr] Name Type Address Offset
> > > > Size EntSize Flags Link Info Align
> > > > [ 0] NULL 0000000000000000 00000000
> > > > 0000000000000000 0000000000000000 0 0 0
> > > > [ 1] foo PROGBITS 0000000000401000 00001000
> > > > 0000000000000001 0000000000000000 AX 0 0 1
> > > > [ 2] .eh_frame_hdr PROGBITS 0000000000402000 00002000
> > > > 0000000000000014 0000000000000000 A 0 0 4
> > > > [ 3] .eh_frame PROGBITS 0000000000402018 00002018
> > > > 000000000000002c 0000000000000000 A 0 0 8
> > > > [ 4] .symtab SYMTAB 0000000000000000 00002048
> > > > 00000000000000d8 0000000000000018 5 5 8
> > > > [ 5] .strtab STRTAB 0000000000000000 00002120
> > > > 000000000000002c 0000000000000000 0 0 1
> > > > [ 6] .shstrtab STRTAB 0000000000000000 0000214c
> > > > 0000000000000037 0000000000000000 0 0 1
> > > > Key to Flags:
> > > > W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
> > > > L (link order), O (extra OS processing required), G (group), T (TLS),
> > > > C (compressed), x (unknown), o (OS specific), E (exclude),
> > > > l (large), p (processor specific)
> > > >
> > > > There are no section groups in this file.
> > > >
> > > > Program Headers:
> > > > Type Offset VirtAddr PhysAddr
> > > > FileSiz MemSiz Flags Align
> > > > LOAD 0x0000000000001000 0x0000000000401000 0x0000000000401000
> > > > 0x0000000000000001 0x0000000000000001 R E 0x1000
> > > > LOAD 0x0000000000002000 0x0000000000402000 0x0000000000402000
> > > > 0x0000000000000044 0x0000000000000044 R 0x1000
> > > > GNU_EH_FRAME 0x0000000000002000 0x0000000000402000 0x0000000000402000
> > > > 0x0000000000000014 0x0000000000000014 R 0x4
> > > >
> > > > Section to Segment mapping:
> > > > Segment Sections...
> > > > 00 foo
> > > > 01 .eh_frame_hdr .eh_frame
> > > > 02 .eh_frame_hdr
> > > >
> > > > There is no dynamic section in this file.
> > > >
> > > > There are no relocations in this file.
> > > >
> > > > The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported.
> > > >
> > > > Symbol table '.symtab' contains 9 entries:
> > > > Num: Value Size Type Bind Vis Ndx Name
> > > > 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
> > > > 1: 0000000000401000 0 SECTION LOCAL DEFAULT 1
> > > > 2: 0000000000402000 0 SECTION LOCAL DEFAULT 2
> > > > 3: 0000000000402018 0 SECTION LOCAL DEFAULT 3
> > > > 4: 0000000000402000 0 NOTYPE LOCAL DEFAULT 2 __GNU_EH_FRAME_HDR
> > > > 5: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND _start
> > > > 6: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 3 __bss_start
> > > > 7: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 3 _edata
> > > > 8: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 3 _end
> > > >
> > > > No version information found in this file.
> > > >
> > > > umb at ubuntu:~/tests/81$ readelf -a with_hdr -wf
> > > > ELF Header:
> > > > Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
> > > > Class: ELF64
> > > > Data: 2's complement, little endian
> > > > Version: 1 (current)
> > > > OS/ABI: UNIX - System V
> > > > ABI Version: 0
> > > > Type: EXEC (Executable file)
> > > > Machine: Advanced Micro Devices X86-64
> > > > Version: 0x1
> > > > Entry point address: 0x401000
> > > > Start of program headers: 64 (bytes into file)
> > > > Start of section headers: 8584 (bytes into file)
> > > > Flags: 0x0
> > > > Size of this header: 64 (bytes)
> > > > Size of program headers: 56 (bytes)
> > > > Number of program headers: 3
> > > > Size of section headers: 64 (bytes)
> > > > Number of section headers: 7
> > > > Section header string table index: 6
> > > >
> > > > Section Headers:
> > > > [Nr] Name Type Address Offset
> > > > Size EntSize Flags Link Info Align
> > > > [ 0] NULL 0000000000000000 00000000
> > > > 0000000000000000 0000000000000000 0 0 0
> > > > [ 1] foo PROGBITS 0000000000401000 00001000
> > > > 0000000000000001 0000000000000000 AX 0 0 1
> > > > [ 2] .eh_frame_hdr PROGBITS 0000000000402000 00002000
> > > > 0000000000000014 0000000000000000 A 0 0 4
> > > > [ 3] .eh_frame PROGBITS 0000000000402018 00002018
> > > > 000000000000002c 0000000000000000 A 0 0 8
> > > > [ 4] .symtab SYMTAB 0000000000000000 00002048
> > > > 00000000000000d8 0000000000000018 5 5 8
> > > > [ 5] .strtab STRTAB 0000000000000000 00002120
> > > > 000000000000002c 0000000000000000 0 0 1
> > > > [ 6] .shstrtab STRTAB 0000000000000000 0000214c
> > > > 0000000000000037 0000000000000000 0 0 1
> > > > Key to Flags:
> > > > W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
> > > > L (link order), O (extra OS processing required), G (group), T (TLS),
> > > > C (compressed), x (unknown), o (OS specific), E (exclude),
> > > > l (large), p (processor specific)
> > > >
> > > > There are no section groups in this file.
> > > >
> > > > Program Headers:
> > > > Type Offset VirtAddr PhysAddr
> > > > FileSiz MemSiz Flags Align
> > > > LOAD 0x0000000000001000 0x0000000000401000 0x0000000000401000
> > > > 0x0000000000000001 0x0000000000000001 R E 0x1000
> > > > LOAD 0x0000000000002000 0x0000000000402000 0x0000000000402000
> > > > 0x0000000000000044 0x0000000000000044 R 0x1000
> > > > GNU_EH_FRAME 0x0000000000002000 0x0000000000402000 0x0000000000402000
> > > > 0x0000000000000014 0x0000000000000014 R 0x4
> > > >
> > > > Section to Segment mapping:
> > > > Segment Sections...
> > > > 00 foo
> > > > 01 .eh_frame_hdr .eh_frame
> > > > 02 .eh_frame_hdr
> > > >
> > > > There is no dynamic section in this file.
> > > >
> > > > There are no relocations in this file.
> > > >
> > > > The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported.
> > > >
> > > > Symbol table '.symtab' contains 9 entries:
> > > > Num: Value Size Type Bind Vis Ndx Name
> > > > 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
> > > > 1: 0000000000401000 0 SECTION LOCAL DEFAULT 1
> > > > 2: 0000000000402000 0 SECTION LOCAL DEFAULT 2
> > > > 3: 0000000000402018 0 SECTION LOCAL DEFAULT 3
> > > > 4: 0000000000402000 0 NOTYPE LOCAL DEFAULT 2 __GNU_EH_FRAME_HDR
> > > > 5: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND _start
> > > > 6: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 3 __bss_start
> > > > 7: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 3 _edata
> > > > 8: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 3 _end
> > > >
> > > > No version information found in this file.
> > > > Contents of the .eh_frame section:
> > > >
> > > >
> > > > 00000000 0000000000000014 00000000 CIE
> > > > Version: 1
> > > > Augmentation: "zR"
> > > > Code alignment factor: 1
> > > > Data alignment factor: -8
> > > > Return address column: 16
> > > > Augmentation data: 1b
> > > > DW_CFA_def_cfa: r7 (rsp) ofs 8
> > > > DW_CFA_offset: r16 (rip) at cfa-8
> > > > DW_CFA_nop
> > > > DW_CFA_nop
> > > >
> > > > 00000018 0000000000000010 0000001c FDE cie=00000000 pc=0000000000401000..0000000000401001
> > > > DW_CFA_nop
> > > > DW_CFA_nop
> > > > DW_CFA_nop
> > > >
> > > >
> > > > ```
> > > >
> > > > I also see ".eh_frame" dumped when there is no ".eh_frame_hdr":
> > > >
> > > >
> > > > ```
> > > > umb at ubuntu:~/tests/81$ readelf -a wo_hdr -wf
> > > > ELF Header:
> > > > Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
> > > > Class: ELF64
> > > > Data: 2's complement, little endian
> > > > Version: 1 (current)
> > > > OS/ABI: UNIX - System V
> > > > ABI Version: 0
> > > > Type: EXEC (Executable file)
> > > > Machine: Advanced Micro Devices X86-64
> > > > Version: 0x1
> > > > Entry point address: 0x401000
> > > > Start of program headers: 64 (bytes into file)
> > > > Start of section headers: 8480 (bytes into file)
> > > > Flags: 0x0
> > > > Size of this header: 64 (bytes)
> > > > Size of program headers: 56 (bytes)
> > > > Number of program headers: 2
> > > > Size of section headers: 64 (bytes)
> > > > Number of section headers: 6
> > > > Section header string table index: 5
> > > >
> > > > Section Headers:
> > > > [Nr] Name Type Address Offset
> > > > Size EntSize Flags Link Info Align
> > > > [ 0] NULL 0000000000000000 00000000
> > > > 0000000000000000 0000000000000000 0 0 0
> > > > [ 1] foo PROGBITS 0000000000401000 00001000
> > > > 0000000000000001 0000000000000000 AX 0 0 1
> > > > [ 2] .eh_frame PROGBITS 0000000000402000 00002000
> > > > 000000000000002c 0000000000000000 A 0 0 8
> > > > [ 3] .symtab SYMTAB 0000000000000000 00002030
> > > > 00000000000000a8 0000000000000018 4 3 8
> > > > [ 4] .strtab STRTAB 0000000000000000 000020d8
> > > > 0000000000000019 0000000000000000 0 0 1
> > > > [ 5] .shstrtab STRTAB 0000000000000000 000020f1
> > > > 0000000000000029 0000000000000000 0 0 1
> > > > Key to Flags:
> > > > W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
> > > > L (link order), O (extra OS processing required), G (group), T (TLS),
> > > > C (compressed), x (unknown), o (OS specific), E (exclude),
> > > > l (large), p (processor specific)
> > > >
> > > > There are no section groups in this file.
> > > >
> > > > Program Headers:
> > > > Type Offset VirtAddr PhysAddr
> > > > FileSiz MemSiz Flags Align
> > > > LOAD 0x0000000000001000 0x0000000000401000 0x0000000000401000
> > > > 0x0000000000000001 0x0000000000000001 R E 0x1000
> > > > LOAD 0x0000000000002000 0x0000000000402000 0x0000000000402000
> > > > 0x000000000000002c 0x000000000000002c R 0x1000
> > > >
> > > > Section to Segment mapping:
> > > > Segment Sections...
> > > > 00 foo
> > > > 01 .eh_frame
> > > >
> > > > There is no dynamic section in this file.
> > > >
> > > > There are no relocations in this file.
> > > >
> > > > The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported.
> > > >
> > > > Symbol table '.symtab' contains 7 entries:
> > > > Num: Value Size Type Bind Vis Ndx Name
> > > > 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
> > > > 1: 0000000000401000 0 SECTION LOCAL DEFAULT 1
> > > > 2: 0000000000402000 0 SECTION LOCAL DEFAULT 2
> > > > 3: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND _start
> > > > 4: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 2 __bss_start
> > > > 5: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 2 _edata
> > > > 6: 0000000000404000 0 NOTYPE GLOBAL DEFAULT 2 _end
> > > >
> > > > No version information found in this file.
> > > > Contents of the .eh_frame section:
> > > >
> > > >
> > > > 00000000 0000000000000014 00000000 CIE
> > > > Version: 1
> > > > Augmentation: "zR"
> > > > Code alignment factor: 1
> > > > Data alignment factor: -8
> > > > Return address column: 16
> > > > Augmentation data: 1b
> > > > DW_CFA_def_cfa: r7 (rsp) ofs 8
> > > > DW_CFA_offset: r16 (rip) at cfa-8
> > > > DW_CFA_nop
> > > > DW_CFA_nop
> > > >
> > > > 00000018 0000000000000010 0000001c FDE cie=00000000 pc=0000000000401000..0000000000401001
> > > > DW_CFA_nop
> > > > DW_CFA_nop
> > > > DW_CFA_nop
> > > >
> > > > }
> > > > ```
> > > >
> > > > Since we have such differences in the behavior, should we just test the current behavior atm?
> > > > I.e. before this diff I tested "EH_FRAME Header [", now I also added a check for ".eh_frame section at offset...".
> > > > Both of them are dumped at the top level currently. Seems reasonable to test the fact we do that (with just `-all`)
> > > > and the order, probably?
> > > > (I am ok to change it in any way actually, but just wanted to clarify this before doing anything with it.)
> > > I'm confused too. Your output above even appears to be conflicted. Note that it mentions "The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported."
> > >
> > > Anyway, probably best to file a bug to record the issue and then do as you're doing here (i.e. test the current behaviour).
> > > Note that it mentions "The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported."
> >
> > Yes, that looks strange. I'll build the latest binutils from sources tomorrow and check what it do, then probably file a bug or prepare a patch. Thanks for review!
> I've build GNU readelf (GNU Binutils) 2.33.50.20191008 today and it still shows
> "The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported."
> for me when I request "-a" or "-u" (--unwind Display the unwind info (if present))
>
> It seems to be a known one year old bug:
> https://bugzilla.redhat.com/show_bug.cgi?id=1626614
>
> And one of interesting comments is:
> "A workaround is readelf -wF or -wf however, it is unclear to me why -u isn't wired up to do the same thing as -wf. Is that something worth considering?"
>
> I am going to commit this patch and do nothing else for it atm (i.e. will not report any bugs for llvm-readelf until situation with GNU be fixed, since the current our behavior looks valid and I probably see no issues). How does it sound for you?
Sounds good!
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