how to disable mouse pointer acceleration on android - by slonkazoid

suffering through android system libraries

how to disable mouse pointer acceleration on android

-or, why my workspaces look like this

a tale of laziness and assembly patching

if you are only interested in the tutorial, skip to that section

android has pointer acceleration???

yes. yes it does. turns out this can be disabled with root and an app called SetEdit. oh wait, it no longer works. the acceleration is hardcoded now.

how to disable mouse pointer acceleration on kde plasma

1. press the super/windows/meta key
2. type "Mouse"
3. press enter/click on the Mouse option
4. change "Pointer acceleration" from "Standard" to "None"

tutorial

required tools: Ghidra, adb & fastboot (fastboot for contingency), Magisk already installed and set up, a hex editor (i used hexedit), patience, lack of self respect, abnormal understanding of priorities, a browser

assumes you have experience in writing Magisk modules, patching assembly using a hex editor, reading C & C++, and using a browser

set up a workspace

make a directory for all this stuff and cd into it

mkdir ~/accel
cd ~/accel
mkdir ghidra        # ghidra project dir
mkdir disable-accel # magisk module dir

launch ghidra and create a project in the ghidra directory. the name doesn't matter.

download your ROM's clean boot.img file or generate it somehow. this is for if when you bootloop your phone.

locate and transfer the libinput.so file

connect to your phone using adb. the libinput.so file should be at /system/lib64/libinput.so. retrieve it using adb pull.

adb pull /system/lib64/libinput.so
cp libinput.so{,.bak} # copy to libinput.so.bak, just in case

disassemble it

open the CodeBrowser tool from the tool chest in ghidra

drag & drop the libinput.so file on the CodeBrowser (which i will just call 'ghidra')

navigate to your android version's libs/inputs/VelocityControl.cpp file. here's it from the commit i will use as a reference.

locate the these lines in the assembly. in my case they were located at the address 00149478, which is byte 0x0049478 in the actual file.

now all you have to do is to patch the str (store) calls with a nop. you want to do this for both deltaX and deltaY or you will have pointer acceleration in one direction which is truthfully horrifying.

first, take note of the address and the bytes of the str instructions. mine were at 00149490 and 001494a0, and the instruction bytes were 80 02 00 bd and 60 02 00 bd. you will use these to locate the instructions in the hex editor.

then, right click the str instruction and choose "Patch Instruction" from the context menu. the first time you do this a loading popup will appear, it will take a good while to load.

after it loads, remove the parameters (right side), and replace the instruction (left side) with a nop.

press enter to make the change. the instruction bytes should now be 1f 20 03 d5, but if you are reading this in the future with an arm64v21 cpu or something it might be different. i will refer to the nop instruction bytes by their value (1f 20 03 d5) for the rest of this post.

repeat for the other delta variable.

edit the binary

in the end, i had made 2 changes to the binary

address 00149490 (actual location 0x049490): 80 02 00 bd -> 1f 20 03 d5 address 001494a0 (actual location 0x0494a0): 60 02 00 bd -> 1f 20 03 d5

i changed these bytes in the hex editor and saved the file

create a Magisk module

if you don't know how to do this, follow the official guide

edit the disable-accel/magisk.prop file. you can just paste the content below or write your own.

id=disable-pointer-acceleration
name="Disable pointer acceleration"
version=v1
versionCode=1
author=me
description="Disable pointer acceleration on Android by patching the libinput.so file"

copy the libinput.so file to disable-accel/system/lib64/libinput.so

mkdir -p disable-accel/system/lib64
cp libinput.so disable-accel/system/lib64

push the module to your phone and reboot

adb push disable-accel /data/adb/modules
adb reboot

my phone is bootlooping

good job. i bootlooped my phone several times while trying to figure this out. what worked was not using ghidra's export feature but using a hex editor to patch the binary myself.

to un-bootloop your phone, follow these steps:

1. boot to fastboot and fastboot flash boot boot.img
2. reboot into your now no longer bootlooping ROM and run adb shell rm -rf /data/adb/modules/disable-accel
3. reinstall magisk

questions

you can find my contact information on my website: https://slonk.ing/#contact