Re: [PATCH v2 2/6] perf arm_spe: Handle missing CPU IDs

[Leo Yan]

On Tue, Apr 07, 2026 at 03:05:16PM +0100, James Clark wrote:
> Don't call strtol() with a null pointer to avoid undefined behavior.
> 
> I'm not sure of the exact scenario for missing CPU IDs but I don't think
> it happens in practice. SPE decoding can continue without them with
> reduced functionality, but print an error message anyway.
> 
> Signed-off-by: James Clark <james.clark@xxxxxxxxxx>

Reviewed-by: Leo Yan <leo.yan@xxxxxxx>

> ---
>  tools/perf/util/arm-spe.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index 7447b000f9cd..fc11f32e4911 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -968,16 +968,23 @@ static int arm_spe__get_midr(struct arm_spe *spe, int cpu, u64 *midr)
>  
>  		pr_warning_once("Old SPE metadata, re-record to improve decode accuracy\n");
>  		cpuid = perf_env__cpuid(perf_session__env(spe->session));
> +		if (!cpuid)
> +			goto err;
> +
>  		*midr = strtol(cpuid, NULL, 16);
>  		return 0;
>  	}
>  
>  	metadata = arm_spe__get_metadata_by_cpu(spe, cpu);
>  	if (!metadata)
> -		return -EINVAL;
> +		goto err;
>  
>  	*midr = metadata[ARM_SPE_CPU_MIDR];
>  	return 0;
> +
> +err:
> +	pr_err("Failed to get MIDR for CPU %d\n", cpu);
> +	return -EINVAL;
>  }
>  
>  static void arm_spe__synth_ds(struct arm_spe_queue *speq,
> 
> -- 
> 2.34.1
> 
>