On 30 May 2013 17:22, Fabien Chouteau <chout...@adacore.com> wrote:
> I'm not sure this was expected or not, but it looks like the "||" should
> be a "&&". Otherwise it's not possible to disable interrupt.
>
> Signed-off-by: Fabien Chouteau <chout...@adacore.com>
We've had people trying to fiddle with this bit of code
before. I'd like to see a clear description of:
* the bug (ideally with a test case)
* why this patch fixes it (probably with reference to the
architecture manual and to what QEMU means when it sets
"CPSR_I" on M profile [hint: look at how we handle PRIMASK])
* a demonstration that it doesn't break non-M-profile
> @@ -462,8 +462,8 @@ int cpu_exec(CPUArchState *env)
> We avoid this by disabling interrupts when
> pc contains a magic address. */
> if (interrupt_request & CPU_INTERRUPT_HARD
> - && ((IS_M(env) && env->regs[15] < 0xfffffff0)
> - || !(env->uncached_cpsr & CPSR_I))) {
> + && (IS_M(env) && env->regs[15] < 0xfffffff0)
> + && !(env->uncached_cpsr & CPSR_I)) {
> env->exception_index = EXCP_IRQ;
> cc->do_interrupt(cpu);
> next_tb = 0;
...for instance this change means that the if() condition
will now never be satisfied for a non-M-profile core,
which is definitely wrong.
I think you're right that there is a bug in this conditional,
but your patch is not fixing it.
thanks
-- PMM
