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RL-ARM V4 SWI_Handler problem

Eric Severson

I just upgraded from version 3.80 RL-ARM, RVMDK to version 4.0 and all of the sudden some of my software interrupt functions have stopped working.

My problem seems to be an issue with a SWI function that has a return value. [NOTE: I had no issues with this in 3.80]. What ends up happening is that the stack pointer gets corrupted and SWI_Handler( ) is not able to properly restore the CPSR

This is my swi function:

unsigned int __swi(0x08) pmalloc (int size) ;
unsigned int __SWI_8             (int size) {

        NUMpmalloc++;
        return ((unsigned int)malloc(size));     // Protected malloc
        }

Here's where the problem occurs in SWI_Handler( )

{
.
.
.
L250:        MOV     LR,PC                   ; Return Address
L251:        BX      R12                     ; Call SWI Function
L252:        LDMFD   SP!,{R8,PC}^            ; Restore R8 and Return
}

L251 is where the SWI function gets called. The problem is that the stack pointer value at L251 does not equal the stack pointer value at L252, so when the function attempts to return back to my code things don't work properly. This version 4 SWI_Handler( ) function is the same as the SWI_Handler ( ) function from version 3.8

Any thoughts you might have would be greatly appreciated!

Thanks,
Eric

Parents
  • 0 in reply to Eric Severson

    There is no need to protect malloc with SWI because it is already thread-safe.

    Some additional lock mechanisms were introduced in RL-ARM 4.0 (to remove interrupt blocking problem in rare situations as described in the release notes). This currently prevents execution of malloc from SWI handlers.

    If SWI protection of malloc is still required (for example using malloc in interrupt handlers) then contact Keil support for an updated RL-ARM.

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  • 0 in reply to Eric Severson

    There is no need to protect malloc with SWI because it is already thread-safe.

    Some additional lock mechanisms were introduced in RL-ARM 4.0 (to remove interrupt blocking problem in rare situations as described in the release notes). This currently prevents execution of malloc from SWI handlers.

    If SWI protection of malloc is still required (for example using malloc in interrupt handlers) then contact Keil support for an updated RL-ARM.

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