Re: [PATCH V4 04/16] perf, x86: Basic Haswell LBR call stack support

[Peter Zijlstra]

On Mon, Jun 30, 2014 at 04:50:41PM +0800, Yan, Zheng wrote:
> @@ -438,8 +451,11 @@ static int intel_pmu_setup_hw_lbr_filter(struct perf_event *event)
>  	reg = &event->hw.branch_reg;
>  	reg->idx = EXTRA_REG_LBR;
>  
> -	/* LBR_SELECT operates in suppress mode so invert mask */
> -	reg->config = ~mask & x86_pmu.lbr_sel_mask;
> +	/*
> +	 * the first 8 bits (LBR_SEL_MASK) in LBR_SELECT operates
> +	 * in suppress mode so invert mask
> +	 */
> +	reg->config = mask ^ x86_pmu.lbr_sel_mask;

Where the comment made sense with the old code; it doesn't really with
the new..

Attachment: pgp98Rp2wLHL8.pgp
Description: PGP signature