On Wed, Jun 25, 2014 at 8:39 AM, Alistair Francis
<alistair.fran...@xilinx.com> wrote:
> On Wed, Jun 25, 2014 at 1:55 AM, Christopher Covington
> <c...@codeaurora.org> wrote:
>> On 06/23/2014 09:12 PM, Alistair Francis wrote:
>>> Call the new pmccntr_sync() function when there is a possibility
>>> of swapping ELs (I.E. when there is an exception)
>>>
>>> Signed-off-by: Alistair Francis <alistair.fran...@xilinx.com>
>>> ---
>>>
>>> target-arm/helper-a64.c | 5 +++++
>>> target-arm/helper.c | 7 +++++++
>>> target-arm/op_helper.c | 6 ++++++
>>> 3 files changed, 18 insertions(+), 0 deletions(-)
>>>
>>> diff --git a/target-arm/helper-a64.c b/target-arm/helper-a64.c
>>> index 2b4ce6a..b61174f 100644
>>> --- a/target-arm/helper-a64.c
>>> +++ b/target-arm/helper-a64.c
>>> @@ -446,6 +446,8 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
>>> target_ulong addr = env->cp15.vbar_el[1];
>>> int i;
>>>
>>> + pmccntr_sync(env);
>>> +
>>> if (arm_current_pl(env) == 0) {
>>> if (env->aarch64) {
>>> addr += 0x400;
>>> @@ -484,6 +486,7 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
>>> addr += 0x100;
>>> break;
>>> default:
>>> + pmccntr_sync(env);
>>> cpu_abort(cs, "Unhandled exception 0x%x\n", cs->exception_index);
Not sure you need this, there is not much point in causing your side
effects right before an assertion (via cpu_abort).
>>> }
>>>
>>> @@ -511,4 +514,6 @@ void aarch64_cpu_do_interrupt(CPUState *cs)
>>>
>>> env->pc = addr;
>>> cs->interrupt_request |= CPU_INTERRUPT_EXITTB;
>>> +
>>> + pmccntr_sync(env);
>>> }
>>
>> The double calls seem unwieldy. I think it could be made into a single
>> function call if there was access, perhaps as a second parameter or maybe as
>> a
>> static variable, to both the previous and current state so the function could
>> tell whether there is no transition, enable->disable, or disable->enable.
>>
>
> The problem with a parameter is that the state of the enabled register needs
> to be saved at the start of any code that will enable/disable the register. So
> it ends up being just as messy.
>
> Static variables won't work if there are multiple CPUs. I guess an
> array of statics
> could work, but I don't like that method
>
> I feel that just calling the function twice ends up being neat and
> works pretty well
>
Theres a third option. Create a new function that explicitly changes EL:
arm_change_el(int new) {
sync();
env->el = new;
sync();
}
And update the interrupt path functions to use it instead of direct
env manipulation.
The advantage of this, is others can also add el switching side
effects in one place. I doubt this is the last time we will want to
trap EL changes for system level side effects.
Regards,
Peter
>> Christopher
>>
>> --
>> Employee of Qualcomm Innovation Center, Inc.
>> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>> hosted by the Linux Foundation.
>>
>
