Re: [PATCH v4 6/7] tracing/probes: Add this_cpu_read() and this_cpu_ptr() dereference method to fetcharg

[Google]

On Mon, 15 Jun 2026 10:14:54 +0900
"Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote:

> +		case FETCH_OP_DEREF_CPU:
> +			val = (unsigned long)this_cpu_ptr((void __percpu *)val);
> +			ret = probe_mem_read(&val, (void *)val, sizeof(val));
> +			break;
> +		case FETCH_OP_CPU_PTR:
> +			val = (unsigned long)this_cpu_ptr((void __percpu *)val);
> +			ret = 0;
> +			break;

Hmm, maybe I can just convert the FETCH_OP_DEREF_CPU to
FETCH_OP_CPU_PTR + FETCH_OP_DEREF to simply the code.

> +		default:
> +			lval = llval;
> +			goto out;
> +		}
>  		if (ret)
>  			return ret;
> +		llval = lval;
>  		code++;
>  	} while (1);
> +out:
>  
>  	s3 = code;
>  stage3:
> @@ -181,6 +195,10 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
>  	case FETCH_OP_ST_UMEM:
>  		probe_mem_read_user(dest, (void *)val + code->offset, code->size);
>  		break;
> +	case FETCH_OP_ST_CPUMEM:
> +		val = (unsigned long)this_cpu_ptr((void __percpu *)val);
> +		probe_mem_read(dest, (void *)val, code->size);
> +		break;

Then, I can just drop this change.

Thanks,


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>