This may be a stupid question, but in my assembly code, during debugging, I have
pop{r2-r6,pc}
and I think it is giving me an hard fault exception. I understand what pop does, but I am unsure what the pc part means. I cannot find it explained anywhere on the internet and it is not a variable in my code anywhere.
I am using keil on an stm32 in c++
pc or r15 is the program counter, the register which gives the address that the processor fetches instructions from. Changing it to another address makes the program execution jump to that address.
In this case, the address is read off the stack to return from a function call; the return address would have been pushed onto the stack (from the link register lr or r14) at the start of the function.
If that's causing a crash, then it's probably because the address on the stack has been corrupted. Perhaps you're writing outside the bounds of a local array, or overflowing the stack with too deep a function call level.