> On 24-Jul-2020, at 5:56 PM, Ravi Bangoria <ravi.bango...@linux.ibm.com> wrote:
> 
> Hi Athira,
> 
>> +/* Function to return the extended register values */
>> +static u64 get_ext_regs_value(int idx)
>> +{
>> +    switch (idx) {
>> +    case PERF_REG_POWERPC_MMCR0:
>> +            return mfspr(SPRN_MMCR0);
>> +    case PERF_REG_POWERPC_MMCR1:
>> +            return mfspr(SPRN_MMCR1);
>> +    case PERF_REG_POWERPC_MMCR2:
>> +            return mfspr(SPRN_MMCR2);
>> +    default: return 0;
>> +    }
>> +}
>> +
>>  u64 perf_reg_value(struct pt_regs *regs, int idx)
>>  {
>> -    if (WARN_ON_ONCE(idx >= PERF_REG_POWERPC_MAX))
>> -            return 0;
>> +    u64 PERF_REG_EXTENDED_MAX;
> 
> PERF_REG_EXTENDED_MAX should be initialized. otherwise ...
> 
>> +
>> +    if (cpu_has_feature(CPU_FTR_ARCH_300))
>> +            PERF_REG_EXTENDED_MAX = PERF_REG_MAX_ISA_300;
>>      if (idx == PERF_REG_POWERPC_SIER &&
>>         (IS_ENABLED(CONFIG_FSL_EMB_PERF_EVENT) ||
>> @@ -85,6 +103,16 @@ u64 perf_reg_value(struct pt_regs *regs, int idx)
>>          IS_ENABLED(CONFIG_PPC32)))
>>              return 0;
>>  +   if (idx >= PERF_REG_POWERPC_MAX && idx < PERF_REG_EXTENDED_MAX)
>> +            return get_ext_regs_value(idx);
> 
> On non p9/p10 machine, PERF_REG_EXTENDED_MAX may contain random value which 
> will
> allow user to pass this if condition unintentionally.

> 
> Neat: PERF_REG_EXTENDED_MAX is a local variable so it should be in lowercase.
> Any specific reason to define it in capital?

Hi Ravi

There is no specific reason. I will include both these changes in next version

Thanks
Athira Rajeev


> 
> Ravi

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