Hi,
I have a machine, an AR7 MIPS router I want to hack, but I'm unable
to run _any_ executable on that machine outside the ones in the firmware.
I tried building a static mips1 binary, but it fails so:
# /var/test.bin
/var/test.bin: 1: Syntax error: "(" unexpected
so I downloaded a binary builtin in the firmware and I compared it to my own:
$ file busybox.bin test.bin
busybox.bin: ELF 32-bit LSB executable, MIPS, MIPS-I version 1 (SYSV), dynamically linked (uses shared libs), stripped
test.bin: ELF 32-bit LSB executable, MIPS, version 1 (SYSV), statically linked, stripped
busybox.bin is the builtin busybox while test.bin is a static HelloWorld
I ran readelf on it:
$ readelf -h busybox.bin
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: MIPS R3000
Version: 0x1
Entry point address: 0x4037e0
Start of program headers: 52 (bytes into file)
Start of section headers: 337304 (bytes into file)
Flags: 0x5, noreorder, cpic, 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: 21
Section header string table index: 20
$ readelf -h test.bin
ELF Header:
Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class: ELF32
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: EXEC (Executable file)
Machine: MIPS R3000
Version: 0x1
Entry point address: 0x400140
Start of program headers: 52 (bytes into file)
Start of section headers: 11780 (bytes into file)
Flags: 0x50001007, noreorder, pic, cpic, o32, mips32
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
Number of program headers: 3
Size of section headers: 40 (bytes)
Number of section headers: 17
Section header string table index: 16
$ diff -u <(readelf -h busybox.bin) <(readelf -h test.bin)
--- /dev/fd/63 2008-02-13 00:26:48.880261477 +0100
+++ /dev/fd/62 2008-02-13 00:26:48.880261477 +0100
@@ -8,13 +8,13 @@
Type: EXEC (Executable file)
Machine: MIPS R3000
Version: 0x1
- Entry point address: 0x4037e0
+ Entry point address: 0x400140
Start of program headers: 52 (bytes into file)
- Start of section headers: 337304 (bytes into file)
- Flags: 0x5, noreorder, cpic, mips1
+ Start of section headers: 11780 (bytes into file)
+ Flags: 0x50001007, noreorder, pic, cpic, o32, mips32
Size of this header: 52 (bytes)
Size of program headers: 32 (bytes)
- Number of program headers: 6
+ Number of program headers: 3
Size of section headers: 40 (bytes)
- Number of section headers: 21
- Section header string table index: 20
+ Number of section headers: 17
+ Section header string table index: 16
The router firmware uses:
# cat /proc/version
Linux version 2.4.17_mvl21-malta-mips_fp_le (root@xxxxxxxxxxxxxxxxxxxxx) (gcc version 2.95.3 20010315 (release/MontaVista)) #1 Fri Mar 18 11:00:12 EST 2005
While I have a gcc-4.2.3 toolchain with 2.6.24 headers.
How can I build a mips1 binary instead of the mips32 I make? Can I disable o32?
Best Regards,
Matteo Croce
