Re: [Qemu-devel] [PATCH v1 7/7] target-arm: Call the pmccntr_sync function when swapping ELs

[Alistair Francis]

On Wed, Jun 25, 2014 at 1:55 AM, Christopher Covington
<address@hidden> 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 <address@hidden>
>> ---
>>
>>  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);
>>      }
>>
>> @@ -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

> Christopher
>
> --
> Employee of Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by the Linux Foundation.
>