I need to learn ARM assembly, and I use Linux.

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chuchi

June 26th, 2012, 04:53 PM

Hi there!!


I need to learn ARM assembly, and I use Linux. Please, could you give me any starting point about how to install it?? I do not pretend that you teach me ARM assembly. Just a link.


thank you very much!!!

youknowme

June 27th, 2012, 05:03 AM

Hi there!!


I need to learn ARM assembly, and I use Linux. Please, could you give me any starting point about how to install it?? I do not pretend that you teach me ARM assembly. Just a link.


thank you very much!!!

This might be useful to start you off

SevenMachines

June 27th, 2012, 08:11 AM

Been a year or so, but i think this works? Although personally I recommend setting up a chroot or pbuilder arm environment, its less hassle with more complicated programs, or at least was in my previous experience.


$ apt-get install gcc-4.6-arm-linux-gnueabi libc6-dev-armel-cross

$ cat hello.s
.data

msg:
.ascii "Hello, ARM World!\n"
len = . - msg


.text

.globl _start
_start:
/* write syscall */
mov %r0, $1
ldr %r1, =msg
ldr %r2, =len
mov %r7, $4
swi $0

/* exit syscall */
mov %r0, $0
mov %r7, $1
swi $0


$ arm-linux-gnueabi-as -o hello.o hello.s

$ arm-linux-gnueabi-ld -o hello hello.o

$ file hello
hello: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, not stripped

$ ./hello
Hello, ARM World!

chuchi

June 27th, 2012, 06:35 PM

Hi!! thank you very much for reply. But that type of instructions is of the form: Mov source,dest. The syntax instructions on ARM is : Mov dest,source. This is what I need

Thank you very much!

chuchi

June 27th, 2012, 06:49 PM

Ok I was wrong, your code is right!! I am very sorry!!

Everything is ok, except when I type ./hello I get



bash: ./hello: cannot execute binary file


Why??

Thank you very much!

SevenMachines

June 27th, 2012, 07:17 PM

Yes. its just at&t syntax versus intel.

Sorry, obviously the binary is arm and not x86 so wont run, I just forgot I had qemu emulation enabled. Try,


$ ./hello
bash: ./hello: cannot execute binary file

# Set up qemu arm emulation
$ sudo apt-get install qemu-user-static

$ ./hello
Hello, ARM World!

chuchi

June 27th, 2012, 07:25 PM

HI!! now it works!! thank you very very much!!

chuchi

June 28th, 2012, 09:48 AM

Hi again!!

Do you know any way of debugging in qemu?

Surfing the net they say you have to install and configure a new kernel. Is there any other way??

thank you very much!!

SevenMachines

June 28th, 2012, 11:21 PM

You can set qemu to wait on a gdb connection


# In a terminal
$ qemu-arm-static -g 10101 ./hello


# In a new terminal
$ sudo apt-get install gdb-multiarch

Then start gdb-multiarch, load symbols, and connect gdb to qemu, eg

$gdb-multiarch

(gdb) list _start
8 .text
9
10 .globl _start
11 _start:
12 /* write syscall */
13 mov %r0, $1
14 ldr %r1, =msg
15 ldr %r2, =len
16 mov %r7, $4
17 swi $0

(gdb) b 16
Breakpoint 1 at 0x8080: file hello.s, line 16.


(gdb) target remote :10101
Remote debugging using :10101
[New Remote target]
[Switching to Remote target]
_start () at hello.s:13
13 mov %r0, $1

(gdb) c
Continuing.

Breakpoint 1, _start () at hello.s:16
16 mov %r7, $4
(gdb) n
17 swi $0
(gdb) n
20 mov %r0, $0
(gdb) c
Continuing.
[Inferior 1 (Remote target) exited normally]


[EDIT] You'll want debugging information ie
$ arm-linux-gnueabi-as -gstabs -o hello.o hello.s