Re: [PATCH v5 03/11] perf/x86/intel/pt: Introduce a new function to get the capability of Intel PT

From: Paolo Bonzini
Date: Mon Mar 19 2018 - 05:04:46 EST


On 19/03/2018 08:17, Kang, Luwei wrote:
>>> +u32 pt_cap_get_ex(u32 *caps, enum pt_capabilities cap) {
>>> + struct pt_cap_desc *cd = &pt_caps[cap];
>>> + u32 c = caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg];
>>> + unsigned int shift = __ffs(cd->mask);
>>> +
>>> + return (c & cd->mask) >> shift;
>>> +}
>>> +EXPORT_SYMBOL_GPL(pt_cap_get_ex);
>>> +
>>
>> You should change pt_cap_get to use this function. Also, "_ex" is not a very common suffix, so perhaps you can call it
>> __pt_cap_get.
>>
>> I don't have any other comments on patches 1-3, so when you resend we can ask the x86 maintainers for approval.
>>
>
> Hi Paolo,
> Is that like this?

Yes, thanks.

Paolo

> --- a/arch/x86/events/intel/pt.c
> +++ b/arch/x86/events/intel/pt.c
> @@ -76,14 +76,20 @@
> PT_CAP(psb_periods, 1, CPUID_EBX, 0xffff0000),
> };
>
> -u32 pt_cap_get(enum pt_capabilities cap)
> +u32 __pt_cap_get(u32 *caps, enum pt_capabilities cap)
> {
> struct pt_cap_desc *cd = &pt_caps[cap];
> - u32 c = pt_pmu.caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg];
> + u32 c = caps[cd->leaf * PT_CPUID_REGS_NUM + cd->reg];
> unsigned int shift = __ffs(cd->mask);
>
> return (c & cd->mask) >> shift;
> }
> +EXPORT_SYMBOL_GPL(__pt_cap_get);
> +
> +u32 pt_cap_get(enum pt_capabilities cap)
> +{
> + return __pt_cap_get(pt_pmu.caps, cap);
> +}
> EXPORT_SYMBOL_GPL(pt_cap_get);
>
> static ssize_t pt_cap_show(struct device *cdev,
> diff --git a/arch/x86/include/asm/intel_pt.h b/arch/x86/include/asm/intel_pt.h
> index 2de4db0..3a4f524 100644
> --- a/arch/x86/include/asm/intel_pt.h
> +++ b/arch/x86/include/asm/intel_pt.h
> @@ -27,9 +27,11 @@ enum pt_capabilities {
> #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
> void cpu_emergency_stop_pt(void);
> extern u32 pt_cap_get(enum pt_capabilities cap);
> +extern u32 __pt_cap_get(u32 *caps, enum pt_capabilities cap);
> #else
> static inline void cpu_emergency_stop_pt(void) {}
> static inline u32 pt_cap_get(enum pt_capabilities cap) { return 0; }
> +static u32 __pt_cap_get(u32 *caps, enum pt_capabilities cap) { return 0; }
>
>
> Thanks,
> Luwei Kang
>