On Tue, Sep 15, 2015 at 07:26:45PM +0100, Will Deacon wrote: > On Mon, Sep 14, 2015 at 09:30:30AM +0100, Jens Wiklander wrote: > > On Fri, Aug 21, 2015 at 01:43:31PM +0200, Jens Wiklander wrote: > > > On Fri, Aug 21, 2015 at 10:24:30AM +0100, Will Deacon wrote: > > > > On Thu, Aug 20, 2015 at 12:37:29PM +0100, Jens Wiklander wrote: > > > > > On Wed, Aug 19, 2015 at 05:50:09PM +0100, Will Deacon wrote: > > > > > > On Wed, Aug 19, 2015 at 09:40:25AM +0100, Jens Wiklander wrote: > > > > > > > + mov x28, x0 > > > > > > > + ldp w0, w1, [x28, #SMC_PARAM_W0_OFFS] > > > > > > > + ldp w2, w3, [x28, #SMC_PARAM_W2_OFFS] > > > > > > > + ldp w4, w5, [x28, #SMC_PARAM_W4_OFFS] > > > > > > > + ldp w6, w7, [x28, #SMC_PARAM_W6_OFFS] > > > > > > > + smc #0 > > > > > > > + stp w0, w1, [x28, #SMC_PARAM_W0_OFFS] > > > > > > > + stp w2, w3, [x28, #SMC_PARAM_W2_OFFS] > > > > > > > + ldp x28, x30, [sp], #16 > > > > > > > + ret > > > > > > > +ENDPROC(smccc_call32) > > > > > > > > > > > > Could we deal with this like we do for PSCI instead? (see > > > > > > __invoke_psci_fn_smc). We could also then rename psci-call.S to fw-call.S > > > > > > and stick this in there too. > > > > > > > > > > I assume you're referring to when to use "hvc" and "smc". > > > > > > > > No, I mean use a C prototype to avoid marshalling the parameters in assembly > > > > like this. As Rutland pointed out, the return value is a bit messy, but > > > > the arguments align nicely with the PCS afaict. > > > > > > If possible I'd like the function to have the same prototype for both > > > arm and arm64. For arm it's not possible to supply more than 4 > > > parameters. To fully support SMC Calling Convention we need to be able > > > to pass 8 parameters and have 4 return values. The OP-TEE driver in this > > > patch set depends on this. I don't see how we can avoid the marshalling > > > here. > > > > > > We could have two versions of the SMCCC functions, one simplified which > > > only uses registers and one complete like this one with marshalling. > > > > Will, what do think about this? > > I still think you should make use of a C prototype to avoid explicit > parameter marshalling in assembly. If you want to maintain a compatible > API between arm and arm64, then you can easily have an intermediate > function in arm64 that sits between the API entry point and the assembly. Yes, I see how that's convenient for passing argument values in registers, but that doesn't help with storing the returned values in x0..x3 into something accessible in C. Am I missing something? Thanks, Jens -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
