1

On my MIPS box I'm trying to run a program. I use a cross compiler for mips. When I run my program, I'm getting

Illegal instruction

I pulled of one binary from it, called cputest. It basically prints “hello world” with some delay. Here is what readelf tells about it:

readelf -a ./cputest.mips 
ELF Header:
  Magic:   7f 45 4c 46 01 02 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, big endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           MIPS R3000
  Version:                           0x1
  Entry point address:               0x4004e0
  Start of program headers:          52 (bytes into file)
  Start of section headers:          1956 (bytes into file)
  Flags:                             0x1007, noreorder, pic, cpic, o32, mips1
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         8
  Size of section headers:           40 (bytes)
  Number of section headers:         20
  Section header string table index: 19

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .interp           PROGBITS        00400134 000134 000014 00   A  0   0  1
  [ 2] .reginfo          MIPS_REGINFO    00400148 000148 000018 18   A  0   0  4
  [ 3] .dynamic          DYNAMIC         00400160 000160 0000c8 08   A  6   0  4
  [ 4] .hash             HASH            00400228 000228 000058 04   A  5   0  4
  [ 5] .dynsym           DYNSYM          00400280 000280 000110 10   A  6   1  4
  [ 6] .dynstr           STRTAB          00400390 000390 0000d0 00   A  0   0  1
  [ 7] .init             PROGBITS        00400460 000460 000028 00  AX  0   0  4
  [ 8] .text             PROGBITS        00400490 000490 0000b0 00  AX  0   0 16
  [ 9] .MIPS.stubs       PROGBITS        00400540 000540 000040 00  AX  0   0  4
  [10] .fini             PROGBITS        00400580 000580 000028 00  AX  0   0  4
  [11] .rodata           PROGBITS        004005a8 0005a8 000010 01 AMS  0   0  4
  [12] .data             PROGBITS        004105c0 0005c0 000010 00  WA  0   0 16
  [13] .rld_map          PROGBITS        004105d0 0005d0 000004 00  WA  0   0  4
  [14] .got              PROGBITS        004105e0 0005e0 000020 04 WAp  0   0 16
  [15] .pdr              PROGBITS        00000000 000600 0000c0 00      0   0  4
  [16] .comment          PROGBITS        00000000 0006c0 000033 01  MS  0   0  1
  [17] .gnu.attributes   LOOS+ffffff5    00000000 0006f3 000010 00      0   0  1
  [18] .mdebug.abi32     PROGBITS        00000010 000703 000000 00      0   0  1
  [19] .shstrtab         STRTAB          00000000 000703 0000a1 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings)
  I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
  O (extra OS processing required) o (OS specific), p (processor specific)

There are no section groups in this file.

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  PHDR           0x000034 0x00400034 0x00400034 0x00100 0x00100 R E 0x4
  INTERP         0x000134 0x00400134 0x00400134 0x00014 0x00014 R   0x1
      [Requesting program interpreter: /lib/ld-uClibc.so.0]
  REGINFO        0x000148 0x00400148 0x00400148 0x00018 0x00018 R   0x4
  LOAD           0x000000 0x00400000 0x00400000 0x005b8 0x005b8 R E 0x10000
  LOAD           0x0005c0 0x004105c0 0x004105c0 0x00040 0x00040 RW  0x10000
  DYNAMIC        0x000160 0x00400160 0x00400160 0x000c8 0x000c8 RWE 0x4
  GNU_STACK      0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x4
  NULL           0x000000 0x00000000 0x00000000 0x00000 0x00000     0x4

 Section to Segment mapping:
  Segment Sections...
   00     
   01     .interp 
   02     .reginfo 
   03     .interp .reginfo .dynamic .hash .dynsym .dynstr .init .text .MIPS.stubs .fini .rodata 
   04     .data .rld_map .got 
   05     .dynamic 
   06     
   07     

Dynamic section at offset 0x160 contains 20 entries:
  Tag        Type                         Name/Value
 0x00000001 (NEEDED)                     Shared library: [libc.so.0]
 0x0000000f (RPATH)                      Library rpath: [/home/xia/Builds/H208N_V1.0_Dev/csp/release/tools/uclibc/lib]
 0x0000000c (INIT)                       0x400460
 0x0000000d (FINI)                       0x400580
 0x00000004 (HASH)                       0x400228
 0x00000005 (STRTAB)                     0x400390
 0x00000006 (SYMTAB)                     0x400280
 0x0000000a (STRSZ)                      208 (bytes)
 0x0000000b (SYMENT)                     16 (bytes)
 0x70000016 (MIPS_RLD_MAP)               0x4105d0
 0x00000015 (DEBUG)                      0x0
 0x00000003 (PLTGOT)                     0x4105e0
 0x70000001 (MIPS_RLD_VERSION)           1
 0x70000005 (MIPS_FLAGS)                 NOTPOT
 0x70000006 (MIPS_BASE_ADDRESS)          0x400000
 0x7000000a (MIPS_LOCAL_GOTNO)           2
 0x70000011 (MIPS_SYMTABNO)              17
 0x70000012 (MIPS_UNREFEXTNO)            19
 0x70000013 (MIPS_GOTSYM)                0xb
 0x00000000 (NULL)                       0x0

There are no relocations in this file.

The decoding of unwind sections for machine type MIPS R3000 is not currently supported.

Symbol table '.dynsym' contains 17 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
     0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 004105c0     0 NOTYPE  GLOBAL DEFAULT   12 _fdata
     2: 00000001     0 SECTION GLOBAL DEFAULT  ABS _DYNAMIC_LINKING
     3: 004185d0     0 NOTYPE  GLOBAL DEFAULT  ABS _gp
     4: 00400490     0 NOTYPE  GLOBAL DEFAULT    8 _ftext
     5: 004105d0     0 OBJECT  GLOBAL DEFAULT   13 __RLD_MAP
     6: 00410600     0 NOTYPE  GLOBAL DEFAULT  ABS __bss_start
     7: 00410600     0 NOTYPE  GLOBAL DEFAULT  ABS _edata
     8: 004105e0     0 OBJECT  GLOBAL DEFAULT  ABS _GLOBAL_OFFSET_TABLE_
     9: 00410600     0 NOTYPE  GLOBAL DEFAULT  ABS _end
    10: 00410600     0 NOTYPE  GLOBAL DEFAULT  ABS _fbss
    11: 00400580    28 FUNC    GLOBAL DEFAULT   10 _fini
    12: 00400490    72 FUNC    GLOBAL DEFAULT    8 main
    13: 00400560     0 FUNC    GLOBAL DEFAULT  UND __uClibc_main
    14: 00400460    28 FUNC    GLOBAL DEFAULT    7 _init
    15: 00400550     0 FUNC    GLOBAL DEFAULT  UND sleep
    16: 00400540     0 FUNC    GLOBAL DEFAULT  UND printf

Histogram for bucket list length (total of 3 buckets):
 Length  Number     % of total  Coverage
      0  0          (  0.0%)
      1  0          (  0.0%)      0.0%
      2  0          (  0.0%)      0.0%
      3  0          (  0.0%)      0.0%
      4  0          (  0.0%)      0.0%
      5  2          ( 66.7%)     62.5%
      6  1          ( 33.3%)    100.0%

No version information found in this file.
Attribute Section: gnu
File Attributes
  Tag_GNU_MIPS_ABI_FP: Soft float

Primary GOT:
 Canonical gp value: 004185d0

 Reserved entries:
   Address     Access  Initial Purpose
  004105e0 -32752(gp) 00000000 Lazy resolver
  004105e4 -32748(gp) 80000000 Module pointer (GNU extension)

 Global entries:
   Address     Access  Initial Sym.Val. Type    Ndx Name
  004105e8 -32744(gp) 00400580 00400580 FUNC     10 _fini
  004105ec -32740(gp) 00400490 00400490 FUNC      8 main
  004105f0 -32736(gp) 00400560 00400560 FUNC    UND __uClibc_main
  004105f4 -32732(gp) 00400460 00400460 FUNC      7 _init
  004105f8 -32728(gp) 00400550 00400550 FUNC    UND sleep
  004105fc -32724(gp) 00400540 00400540 FUNC    UND printf

When I cross compile my program (which just prints “hello world”) without the -static flag and try to run it, here is what happens:

# ls
hello.mips
# ./hello.mips
/bin/sh: ./hello.mips: Permission denied
# chmod +x hello.mips 
# ./hello.mips
/bin/sh: ./hello.mips: not found
# ls -la
drwxrwxrwx    2 zhangxia root            0 Aug  8 00:01 .
drwxr-xr-x    3 zhangxia root            0 Aug  7 22:46 ..
-rwsrwsrwx    1 888      root         5743 Aug  8 00:01 hello.mips

Why can't I find it when it's there?

So I compile it with the -static flag and here is the readelf output (because of size limits here I will put just a part)

readelf -a hello.static 
ELF Header:
  Magic:   7f 45 4c 46 01 02 01 00 00 00 00 00 00 00 00 00 
  Class:                             ELF32
  Data:                              2's complement, big endian
  Version:                           1 (current)
  OS/ABI:                            UNIX - System V
  ABI Version:                       0
  Type:                              EXEC (Executable file)
  Machine:                           MIPS R3000
  Version:                           0x1
  Entry point address:               0x400280
  Start of program headers:          52 (bytes into file)
  Start of section headers:          647608 (bytes into file)
  Flags:                             0x1007, noreorder, pic, cpic, o32, mips1
  Size of this header:               52 (bytes)
  Size of program headers:           32 (bytes)
  Number of program headers:         6
  Size of section headers:           40 (bytes)
  Number of section headers:         33
  Section header string table index: 30

Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0  0
  [ 1] .note.ABI-tag     NOTE            004000f4 0000f4 000020 00   A  0   0  4
  [ 2] .reginfo          MIPS_REGINFO    00400114 000114 000018 18   A  0   0  4
  [ 3] .note.gnu.build-i NOTE            0040012c 00012c 000024 00   A  0   0  4
  [ 4] .rel.dyn          REL             00400150 000150 000098 08   A  0   0  4
  [ 5] .init             PROGBITS        004001e8 0001e8 000098 00  AX  0   0  4
  [ 6] .text             PROGBITS        00400280 000280 07b5a0 00  AX  0   0 16
  [ 7] __libc_freeres_fn PROGBITS        0047b820 07b820 0013a8 00  AX  0   0  4
  [ 8] .fini             PROGBITS        0047cbc8 07cbc8 000054 00  AX  0   0  4
  [ 9] .rodata           PROGBITS        0047cc20 07cc20 015a00 00   A  0   0 16
  [10] .eh_frame         PROGBITS        004a2620 092620 0019a4 00  WA  0   0  4
  [11] .gcc_except_table PROGBITS        004a3fc4 093fc4 00014e 00  WA  0   0  1
  [12] .tdata            PROGBITS        004a4114 094114 000010 00 WAT  0   0  4
  [13] .tbss             NOBITS          004a4124 094124 000018 00 WAT  0   0  4
  [14] .ctors            PROGBITS        004a4124 094124 000008 00  WA  0   0  4
  [15] .dtors            PROGBITS        004a412c 09412c 00000c 00  WA  0   0  4
  [16] .jcr              PROGBITS        004a4138 094138 000004 00  WA  0   0  4
  [17] .data.rel.ro      PROGBITS        004a413c 09413c 00259c 00  WA  0   0  4
  [18] .data             PROGBITS        004a66e0 0966e0 0007c0 00  WA  0   0 16
  [19] __libc_subfreeres PROGBITS        004a6ea0 096ea0 000030 00  WA  0   0  4
  [20] __libc_atexit     PROGBITS        004a6ed0 096ed0 000004 00  WA  0   0  4
  [21] .got              PROGBITS        004a6ee0 096ee0 000a48 04 WAp  0   0 16
  [22] .sdata            PROGBITS        004a7928 097928 000004 00 WAp  0   0  4
  [23] .sbss             NOBITS          004a7930 09792c 0000fc 00 WAp  0   0  8
  [24] .bss              NOBITS          004a7a30 09792c 001c10 00  WA  0   0 16
  [25] __libc_freeres_pt NOBITS          004a9640 09792c 000018 00  WA  0   0  4
  [26] .pdr              PROGBITS        00000000 09792c 006700 00      0   0  4
  [27] .comment          PROGBITS        00000000 09e02c 000039 01  MS  0   0  1
  [28] .gnu.attributes   LOOS+ffffff5    00000000 09e065 000010 00      0   0  1
  [29] .mdebug.abi32     PROGBITS        00001320 09e075 000000 00      0   0  1
  [30] .shstrtab         STRTAB          00000000 09e075 000140 00      0   0  1
  [31] .symtab           SYMTAB          00000000 09e6e0 006d70 10     32 655  4
  [32] .strtab           STRTAB          00000000 0a5450 0065f4 00      0   0  1
Key to Flags:
  W (write), A (alloc), X (execute), M (merge), S (strings)
  I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
  O (extra OS processing required) o (OS specific), p (processor specific)

There are no section groups in this file.

Program Headers:
  Type           Offset   VirtAddr   PhysAddr   FileSiz MemSiz  Flg Align
  REGINFO        0x000114 0x00400114 0x00400114 0x00018 0x00018 R   0x4
  LOAD           0x000000 0x00400000 0x00400000 0x92620 0x92620 R E 0x10000
  LOAD           0x092620 0x004a2620 0x004a2620 0x0530c 0x07038 RW  0x10000
  NOTE           0x0000f4 0x004000f4 0x004000f4 0x00020 0x00020 R   0x4
  NOTE           0x00012c 0x0040012c 0x0040012c 0x00024 0x00024 R   0x4
  TLS            0x094114 0x004a4114 0x004a4114 0x00010 0x00028 R   0x4

 Section to Segment mapping:
  Segment Sections...
   00     .reginfo 
   01     .note.ABI-tag .reginfo .note.gnu.build-id .rel.dyn .init .text __libc_freeres_fn .fini .rodata 
   02     .eh_frame .gcc_except_table .tdata .ctors .dtors .jcr .data.rel.ro .data __libc_subfreeres __libc_atexit .got .sdata .sbss .bss __libc_freeres_ptrs 
   03     .note.ABI-tag 
   04     .note.gnu.build-id 
   05     .tdata .tbss 

There is no dynamic section in this file.

Relocation section '.rel.dyn' at offset 0x150 contains 19 entries:
 Offset     Info    Type            Sym.Value  Sym. Name
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      
00000000  00000000 R_MIPS_NONE      

The decoding of unwind sections for machine type MIPS R3000 is not currently supported.

Symbol table '.symtab' contains 1751 entries:
   Num:    Value  Size Type    Bind   Vis      Ndx Name
     0: 00000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 004000f4     0 SECTION LOCAL  DEFAULT    1 
     2: 00400114     0 SECTION LOCAL  DEFAULT    2 


       1747: 004a5d58    36 OBJECT  GLOBAL DEFAULT   17 _nl_C_LC_IDENTIFICATION
  1748: 004a9580    76 OBJECT  GLOBAL DEFAULT   24 _dl_ns
  1749: 00450f20  3016 FUNC    GLOBAL DEFAULT    6 _nl_load_locale_from_arch
  1750: 004380e0   248 FUNC    WEAK   DEFAULT    6 wctrans

No version information found in this file.

Displaying notes found at file offset 0x000000f4 with length 0x00000020:
  Owner                 Data size   Description
  GNU                  0x00000010   NT_GNU_ABI_TAG (ABI version tag)
    OS: Linux, ABI: 2.6.18

Displaying notes found at file offset 0x0000012c with length 0x00000024:
  Owner                 Data size   Description
  GNU                  0x00000014   NT_GNU_BUILD_ID (unique build ID bitstring)
    Build ID: a56a4b258e108ec9affb61c4a8ba46527052bca9
Attribute Section: gnu
File Attributes
  Tag_GNU_MIPS_ABI_FP: Hard float (double precision)

Both binaries (static and dynamic) runs just fine in quemu and on my second MIPS box. Any thoughts?

Could “Illegal instruction” be due to different ld-uClibc, libc names/versions?

@Stephen-Kitt Here it is

# ldd ./hello.mips 
/bin/sh: ldd: not found

cat proc/version 
Linux version 2.6.30.9 (xia@njzd) (gcc version 4.4.6 (Realtek RSDK-1.5.6p2) ) #2 Wed Apr 29 18:57:54 CST 2015

# cat proc/cpuinfo 
system type: RTL8672 
processor: 0 
cpu model               : 56322 
BogoMIPS: 619.31 
tlb_entries             : 64 
mips16 implemented      : yes

Im running Ubuntu14.04 basicly

mips-gcc -o hello.mips hello.c
mips-gcc -static -o hello.static hello.c

mips gcc is from Debian rep

$ mips-linux-gnu-gcc -v
Using built-in specs.
Target: mips-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.5-8' --with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/mips-linux-gnu/include/c++/4.4.5 --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --disable-libssp --enable-targets=all --enable-checking=release --program-prefix=mips-linux-gnu- --includedir=/usr/mips-linux-gnu/include --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=mips-linux-gnu --with-headers=/usr/mips-linux-gnu/include --with-libs=/usr/mips-linux-gnu/lib
Thread model: posix
gcc version 4.4.5 (Debian 4.4.5-8)

I obtained it from here http://www.emdebian.org/debian/

  • Could you edit your question to add the following information? I'd like to know what OS you're running on the MIPS box, and on the cross-compiler box; it would also help to know how you're cross-compiling. As for your dynamic binary, ldd hello.mips (on your MIPS box) should help explain the “not found” message. – Stephen Kitt Aug 8 '15 at 13:08
  • There is no much tools available, basically there is striped busybox and few others custom made – Slobodan Vidovic Aug 8 '15 at 14:46
  • I totally forgot sorry, that is what I could find, if there is anything else :) – Slobodan Vidovic Aug 8 '15 at 15:33
  • Thanks, could you also show the output of mips-gcc -v? What is your second MIPS box? (And I'm curious as to what you mean by “mips gcc is from Debian rep”... Which Debian repository?) – Stephen Kitt Aug 8 '15 at 15:48
  • I did tried to compile it with march=mips32 and mips32r2 but same deal :) – Slobodan Vidovic Aug 8 '15 at 16:00
1
# cat proc/cpuinfo 
system type: RTL8672 
processor: 0 
cpu model: 56322 

An RTL8672 is not a full MIPS implementation, but a Lexra. You will need a customized toolchain that knows how to handle this.

Something like this, or for a binary-only toolchain, look for rsdk; e.g., this.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.