[PATCH v6 1/6] eal: trace: add trace point emit for blob

[Morten Brørup]

> From: Ankur Dwivedi [mailto:adwivedi at marvell.com]
> Sent: Friday, 20 January 2023 09.41
> 
> Adds a trace point emit function for capturing a blob. The blob
> captures the length passed by the application followed by the array.
> 
> The maximum blob bytes which can be captured is bounded by
> RTE_TRACE_BLOB_LEN_MAX macro. The value for max blob length macro is
> 64 bytes. If the length is less than 64 the remaining trailing bytes
> are set to zero.
> 
> This patch also adds test case for emit blob tracepoint function.
> 
> Signed-off-by: Ankur Dwivedi <adwivedi at marvell.com>
> ---

[...]

> +/** Macro to define maximum emit length of blob. */
> +#define RTE_TRACE_BLOB_LEN_MAX 64
> +
>  /**
>   * Enable recording events of the given tracepoint in the trace
> buffer.
>   *
> @@ -374,12 +387,31 @@ do { \
>  	mem = RTE_PTR_ADD(mem, __RTE_TRACE_EMIT_STRING_LEN_MAX); \
>  } while (0)
> 
> +#define rte_trace_point_emit_blob(in, len) \
> +do { \
> +	if (unlikely(in == NULL)) \
> +		return; \
> +	if (len > RTE_TRACE_BLOB_LEN_MAX) \
> +		len = RTE_TRACE_BLOB_LEN_MAX; \
> +	__rte_trace_point_emit(len, uint8_t); \
> +	memcpy(mem, in, len); \
> +	mem = RTE_PTR_ADD(mem, len); \
> +	memset(mem, 0, RTE_TRACE_BLOB_LEN_MAX - len); \
> +	mem = RTE_PTR_ADD(mem, RTE_TRACE_BLOB_LEN_MAX - len); \

Alternatively (just a suggestion):

	memcpy(mem, in, len); \
	memset(RTE_PTR_ADD(mem, len), 0, RTE_TRACE_BLOB_LEN_MAX - len); \
	mem = RTE_PTR_ADD(mem, RTE_TRACE_BLOB_LEN_MAX); \

(If memset() is annotated to inform the compiler that the mem pointer is constant, the compiler should generate exactly the same code.)

> +} while (0)
> +
>  #else
> 
>  #define __rte_trace_point_emit_header_generic(t) RTE_SET_USED(t)
>  #define __rte_trace_point_emit_header_fp(t) RTE_SET_USED(t)
>  #define __rte_trace_point_emit(in, type) RTE_SET_USED(in)
>  #define rte_trace_point_emit_string(in) RTE_SET_USED(in)
> +#define rte_trace_point_emit_blob(in, len) \
> +do { \
> +	RTE_SET_USED(in); \
> +	RTE_SET_USED(len); \
> +} while (0)
> +
> 
>  #endif /* ALLOW_EXPERIMENTAL_API */
>  #endif /* _RTE_TRACE_POINT_REGISTER_H_ */
> diff --git a/lib/eal/include/rte_trace_point_register.h
> b/lib/eal/include/rte_trace_point_register.h
> index a32f4d731b..7efbac8a72 100644
> --- a/lib/eal/include/rte_trace_point_register.h
> +++ b/lib/eal/include/rte_trace_point_register.h
> @@ -47,6 +47,15 @@ do { \
>  		RTE_STR(in)"[32]", "string_bounded_t"); \
>  } while (0)
> 
> +#define rte_trace_point_emit_blob(in, len) \
> +do { \
> +	RTE_SET_USED(in); \
> +	__rte_trace_point_emit(len, uint8_t); \
> +	__rte_trace_point_emit_field(RTE_TRACE_BLOB_LEN_MAX, \
> +		RTE_STR(in)"["RTE_STR(RTE_TRACE_BLOB_LEN_MAX)"]", \
> +		RTE_STR(uint8_t)); \
> +} while (0)

I guess the variable sized trace entry couldn't be implemented.

Anyway, this BLOB implementation is still very useful!

Acked-by: Morten Brørup <mb at smartsharesystems.com>