While setting up ra "by hand" and transferring control via the jr
is a reasonable optimization, you're otherwise breaking things for SMTC.
While the comments are misleading (they accurately described an earlier
version of the code), the function being called here is ipi_decode(), which
needs a pt_regs * in the first argument (hence the copy of the sp), and
the pointer to the IPI message descriptor in the second.
Do you have access to a 34K to test changes to SMTC? I'd have
expected this one to have been pretty quickly fatal.
Regards,
Kevin K.
> diff --git a/arch/mips/kernel/smtc-asm.S b/arch/mips/kernel/smtc-asm.S
> index 76cb31d..1cb9441 100644
> --- a/arch/mips/kernel/smtc-asm.S
> +++ b/arch/mips/kernel/smtc-asm.S
> @@ -97,15 +97,12 @@ FEXPORT(__smtc_ipi_vector)
> SAVE_ALL
> CLI
> TRACE_IRQS_OFF
> - move a0,sp
> /* Function to be invoked passed stack pad slot 5 */
> lw t0,PT_PADSLOT5(sp)
> /* Argument from sender passed in stack pad slot 4 */
> - lw a1,PT_PADSLOT4(sp)
> - jalr t0
> - nop
> - j ret_from_irq
> - nop
> + lw a0,PT_PADSLOT4(sp)
> + PTR_LA ra, _ret_from_irq
> + jr t0
>
> /*
> * Called from idle loop to provoke processing of queued IPIs
>
>
