HardFault handler asm msp/psp routine

[Simon1]

Trying to track the cause of hardfault handler and got next problem.

MCU - STM32F302CB and i'm using eclipse with gnu mcu plugins. I'm trying to use the following code for assembly part of handler, which determines which stack is used:

 __asm volatile
    (
        " tst lr, #4                                                \n"
        " ite eq                                                    \n"
        " mrseq r0, msp                                             \n"
        " mrsne r0, psp                                             \n"
        " ldr r1, [r0, #24]                                         \n"
        " ldr r2, handler2_address_const                            \n"
        " bx r2                                                     \n"
        " handler2_address_const: .word prvGetRegistersFromStack    \n"
    );

However when hardfault occurs and this piece of code is executing the program just jumps to some strange address and then stops executing. So when i execute line by line (in disassembly) it's happening on branch instruction (line 9). And in r2 there is really an address which is not valid, i mean it is not the address of prvGetRegistersFromStack, they differ.

But if i change code to something like this:

 __asm volatile
    (
        " tst lr, #4                                                \n"
        " ite eq                                                     \n"
        " mrseq r0, msp                                     \n"
        " mrsne r0, psp                                      \n"
        " b prvGetRegistersFromStack            \n"
        
    );

Then it works fine and jumps to this C function which logs stack data.

I've seen this code in a couple of articles. Exactly this code is from:

https://www.freertos.org/Debugging-Hard-Faults-On-Cortex-M-Microcontrollers.html

But it doesn't work for me, what am i missing ?

[Tesla DeLorean]

That looks like an awful hack. Problem with in-line assembler is that it is highly dependent on the compiler/linker version/vendor involved. Most rational people put this stuff in the startup.s file where it belongs.