MCU-PLUS-SDK-AM243X: get exception source info

Sven K

Is it possible to get an information in exception case which show me the exception source?

In Detail, we wanna save the register set in pre-exception state in exception handling. Especially LR, SP and PC are most interesting. This information should be saved to be read out later for further investigation.

The problem is that when entering the abort handlers (f.e. HwiP_undefined_handler on FreeRTOS) the register set of this mode (f.e. UNDEF mode) is active but the pre-exception state is stored in the banked USER-registers (f.e. R14_USER).

Is it possible to access these USER registers in another mode? We can switch to USER mode by manipulating the mode in CPSR and get these registers but can't switch back because USER mode is not privileged to do that.

Is there any solution available to determine f.e. the ProgramCounter from the exception source?

over 3 years ago

0 Karim Jamal over 3 years ago

TI__Expert 5505 points

Hi Sven,

your post has been assigned to one of our Apps team who will answer your question soon

Thanks and best regard

karim

0 Prasad Jondhale over 3 years ago

TI__Mastermind 27743 points

Hi Sven,

We believe, System and User mode are the same set of registers. we don't think there is separate set of banked registers for User mode.

Are you not able to access the registers by switching to SYS mode ?

cps <mode>

.set SYS_MODE, 0x1f

.set SVC_MODE,0x13

.set IRQ_MODE, 0x12

cps #0x1f ; switch to system mode

Also please have a look if below reply on similar thread helps in giving pointer -

https://e2e.ti.com/support/microcontrollers/arm-based-microcontrollers-group/arm-based-microcontrollers---internal/f/arm-based-microcontrollers---internal-forum/1094104/lp-am243-printing-the-stack-frame/4052457#4052457

Regards,

Prasad

0 Sven K over 3 years ago in reply to Prasad Jondhale

Prodigy 80 points

Hi Prasad,

thanks for the fast response. The thread link is not working: "Page not found"

We will try if SYS_MODE will help us, thanks for the advice.

It seems that by defining the abort handler method naked we have the pre-exception state which can be stored. Otherwise on entry of abort handler method some registers will be overwritten. We will examine that approach further.

Regards, Sven