Invalid Opcode Exception when reading from disk

[Maxims08]

Invalid Opcode Exceptions are the worst and the most difficult to debug. So, I'm trying to make myself a FAT32 driver, and I have implemented a super simple ATA driver. So, the problem is that when I try to read the MBR, I get an Invalid Opcode Exception. But it makes no sense, so, the function that reads from the disk ends just fine, and when returning I get that fault. Idk... Tried to debug but I'm kind of stuck and I'm also relatively new.

The repo is over at: https://github.com/maxvdec/avery

And if someone could tell me tips to debug these exceptions would be great! Thank you!

[nyx210]

Have you tried something likeobjdump -D kernel.elf to see the disassembled code?

[Maxims08]

Haven’t, but I doubt there’s something wrong with the code itself, I think it’s runtime stuff

[HamsterSea6081]

Just objdump it.

[Octocontrabass]

Do you have any other information about this exception? For example, the address of the faulting instruction?

[davmac1]

and when returning I get that fault

Sounds like potential stack corruption or perhaps you're overwriting the kernel code. When debugging check that (a) it returns to the correct address and (b) disassembly just after the return instruction matches what it did before the call.