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Questions tagged [thumb2]

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How can I quickly tell which ARM Thumb version a particular piece of code is using?

I'm working with an ARM processor: an STM32F407VGT6 board, which IIUC powers a 32-bit Arm® Cortex®-M4. I need to inspect the binary weight of some instruction, so I used objdump like this: arm-none-...
Alessandro Bertulli's user avatar
1 vote
1 answer

ARM/THUMB assembly mismatch between binaries causes crash

I am trying to play around with an app for Android and every time I try to call a function (lua_gettop() from the Lua 5.1 library) from the app's address space, it hits me with ILL_ILLOPC. I made sure ...
BitFlow's user avatar
  • 11
0 votes
1 answer

Setting Breakpoints on Thumb Instructions in GDB

I'm practicing reversing a stripped arm binary, and found that when I set a breakpoint at say 0x010451, and run the program, gdb spins forever until I hit ctrl+c. When I do, the current pc is at the ...
Caustic's user avatar
  • 101
1 vote
0 answers

Immediate offset LDR in presumed malloc function looks wrong in static analysis

I am attempting to disassemble a ROM image for a BCM4366C [1] after reading a blog post where researchers reversed some other Broadcom chips [2] . I have analyzed the ROM image in Ghidra and I have ...
wcerfgba's user avatar
0 votes
1 answer

Confused about a firmware binary

I'm trying to reverse engineer an ARM Thumb2 firmware binary, and I've come across a few oddities. Parts of the file when treated as RGB binary data form perfect images, which seems unusual for a ...
user avatar
3 votes
2 answers

ARM Thumb2 register usage

I am reversing ARM Thumb2 code. I am looking for a table that shows which registers are used to pass arguments to functions, and which registers must be saved after the function ends. By the way, if ...
Keystone's user avatar
  • 523
0 votes
1 answer

How ida choose arm Thumb/Thumb2

I load binary file to ida and choose arm cpu. How can I see if ida choose on arm/arm Thumb2 / arm Thumb? and how can I change it? Bytes translate is depend witch arm is it(arm/arm Thumb2 / arm ...
Ljohhuh's user avatar
  • 41
1 vote
1 answer

The questions about ADR.W instruction

When reversing a ARM firmware using IDA Pro, I find a instruction: ROM:080461FC 0F F2 24 30 ADR.W R0, aBt_test_mode ; "BT_TEST_MODE" ... ROM:08046524 aBt_test_mode DCB "...
user6903's user avatar
  • 411
3 votes
1 answer

Identify targets of a switch table in ARM

I'm working on a disassembler for ARM Thumb2 (stripped) binaries. I can already recover the CFG of Basic Blocks (BB) that use direct jumps. My next goal is to handle indirect jumps. I'm currently ...
Codoka's user avatar
  • 403