offset of symbol in object file

[cross at proxy dot goblin dot cx (cross)]

G'day,

this is probably somewhat off-topic, but I'm stuck and I guess some people on
this list might have some tips for me, here goes:

I need to extract some specific data from a solaris2.4 object file (a
kernel driver). I need to extract the soc_ucode data from the
/kernel/drv/soc file. I first cross compiled binutils-2.9.5 on my
linux-i386 box to a sparc-sun-solaris2.4 target. That worked fine
and indeed I can run nm, objdump, readelf, etc. on the driver file
with success. The problem is however that I don't seem to grasp where
the actual code is to extract (e.g. what the byte offset if from the
start of the file). I just need to dd the data out of the file,
the size I need to dd is 32K which is the size of the soc_ucode data
type.

Here are some outputs :

[root@proxy:/home/users/devel/devel/usr-sparc/bin]$ ./sparc-sun-solaris2.4-nm soc | grep ucode
000000f8 D soc_ucode
000080f8 D soc_ucode_end                                                                                                                                       

...

[root@proxy:/home/users/devel/devel/usr-sparc/bin]$ ./sparc-sun-solaris2.4-objdump --syms soc | grep ucode
00000000 l    df *ABS*  00000000 soc_ucode.c
000080f8 g     O .data  00000004 soc_ucode_end
000000f8 g     O .data  00008000 soc_ucode                                                                                                                     


....


[root@proxy:/home/users/devel/devel/usr-sparc/bin]$ ./sparc-sun-solaris2.4-readelf -a soc | grep ucode
  00002254  08d09 R_SPARC_HI22          000000f8  soc_ucode                 + 0
  00002258  08d0c R_SPARC_LO10          000000f8  soc_ucode                 + 0
  00002270  06609 R_SPARC_HI22          000080f8  soc_ucode_end             + 0
  00002278  0660c R_SPARC_LO10          000080f8  soc_ucode_end             + 0
   82:        0     0 FILE    LOCAL   0  ABS soc_ucode.c
  102:     80f8     4 OBJECT  GLOBAL  0    3 soc_ucode_end
  141:       f8 32768 OBJECT  GLOBAL  0    3 soc_ucode                                                                                                         


....


[root@proxy:/home/users/devel/devel/usr-sparc/bin]$ ./sparc-sun-solaris2.4-readelf -a soc | more
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:                              REL (Relocatable file)
  Machine:                           Sparc
  Version:                           0x1
  Entry point address:               0x0
  Start of program headers:          0 (bytes into file)
  Start of section headers:          66776 (bytes into file)
  Flags:                             0x0
  Size of this header:               52 (bytes)
  Size of program headers:           0 (bytes)
  Number of program headers:         0
  Size of section headers:           40 (bytes)
  Number of section headers:         14
  Section header string table index: 10
 
Section Headers:
  [Nr] Name              Type            Addr     Off    Size   ES Flg Lk Inf Al
  [ 0]                   NULL            00000000 000000 000000 00      0   0 0
  [ 1] .text             PROGBITS        00000000 000038 004bb8 00  AX  0   0 8
  [ 2] .rodata1          PROGBITS        00000000 004bf0 000230 00  A   0   0 4
  [ 3] .data             PROGBITS        00000000 004e20 0080fc 00 WA   0   0 4
  [ 4] .data1            PROGBITS        00000000 00cf1c 00099e 00 WA   0   0 4
  [ 5] .bss              NOBITS          00000000 00d8bc 000004 00 WA   0   0 4
  [ 6] .symtab           SYMTAB          00000000 00d8bc 0009a0 10      7  53 4
  [ 7] .strtab           STRTAB          00000000 00e25c 00078e 00      0   0 1
  [ 8] .stab.index       PROGBITS        00000000 00e9ec 000048 0c      0   0 4
  [ 9] .comment          PROGBITS        00000000 00ea34 00002c 00      0   0 1
  [10] .shstrtab         STRTAB          00000000 00ea60 000076 00      0   0 1
  [11] .rela.text        RELA            00000000 00ead8 0016c8 0c      6   1 4
  [12] .rela.data        RELA            00000000 0101a0 0000cc 0c      6   3 4
  [13] .stab.indexstr    STRTAB          00000000 01026c 00026a 00      0   0 1                                                                                


Now I started out with this last listing and took 0x004e20 as the starting
offset (the offset of the .data segment) and added 0xf8 to that, so
basically :


unsigned long offset = 0x004e20 + 0xf8 ;

fseek(stream, offset, SEEK_SET);

copy_file_32k();


This however doesn't seem to work because the data I end up seems to be
invalid.

My question is ; how do I compute the acuall offset of the soc_ucode data in
this file ?

Any tips would be greatly appreciated,

Cheers,
flux.
  

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