[v5,06/21] perf arm-spe: Refactor printing string to buffer
diff mbox series

Message ID 20201029071927.9308-7-leo.yan@linaro.org
State New, archived
Headers show
Series
  • perf arm-spe: Refactor decoding & dumping flow
Related show

Commit Message

Leo Yan Oct. 29, 2020, 7:19 a.m. UTC
When outputs strings to the decoding buffer with function snprintf(),
SPE decoder needs to detects if any error returns from snprintf() and if
so needs to directly bail out.  If snprintf() returns success, it needs
to update buffer pointer and reduce the buffer length so can continue to
output the next string into the consequent memory space.

This complex logics are spreading in the function arm_spe_pkt_desc() so
there has many duplicate codes for handling error detecting, increment
buffer pointer and decrement buffer size.

To avoid the duplicate code, this patch introduces a new helper function
arm_spe_pkt_snprintf() which is used to wrap up the complex logics, and
it's used by the caller arm_spe_pkt_desc(); if printing buffer is called
for multiple times in a flow, the error is a cumulative value and simply
returns its final value.

This patch also moves the variable 'blen' as the function's local
variable, this allows to remove the unnecessary braces and improve the
readability.

Suggested-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
---
 .../arm-spe-decoder/arm-spe-pkt-decoder.c     | 263 ++++++++----------
 1 file changed, 113 insertions(+), 150 deletions(-)

Comments

André Przywara Oct. 29, 2020, 10:23 a.m. UTC | #1
On 29/10/2020 07:19, Leo Yan wrote:

Hi,

> When outputs strings to the decoding buffer with function snprintf(),
> SPE decoder needs to detects if any error returns from snprintf() and if
> so needs to directly bail out.  If snprintf() returns success, it needs
> to update buffer pointer and reduce the buffer length so can continue to
> output the next string into the consequent memory space.
> 
> This complex logics are spreading in the function arm_spe_pkt_desc() so
> there has many duplicate codes for handling error detecting, increment
> buffer pointer and decrement buffer size.
> 
> To avoid the duplicate code, this patch introduces a new helper function
> arm_spe_pkt_snprintf() which is used to wrap up the complex logics, and
> it's used by the caller arm_spe_pkt_desc(); if printing buffer is called
> for multiple times in a flow, the error is a cumulative value and simply
> returns its final value.
> 
> This patch also moves the variable 'blen' as the function's local
> variable, this allows to remove the unnecessary braces and improve the
> readability.
> 
> Suggested-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
> Reviewed-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  .../arm-spe-decoder/arm-spe-pkt-decoder.c     | 263 ++++++++----------
>  1 file changed, 113 insertions(+), 150 deletions(-)
> 
> diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> index 04fd7fd7c15f..9147b88ae00c 100644
> --- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> +++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
> @@ -9,6 +9,7 @@
>  #include <endian.h>
>  #include <byteswap.h>
>  #include <linux/bitops.h>
> +#include <stdarg.h>
>  
>  #include "arm-spe-pkt-decoder.h"
>  
> @@ -258,192 +259,154 @@ int arm_spe_get_packet(const unsigned char *buf, size_t len,
>  	return ret;
>  }
>  
> +static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> +				const char *fmt, ...)
> +{
> +	va_list ap;
> +	int ret;
> +
> +	va_start(ap, fmt);
> +	ret = vsnprintf(*buf_p, *blen, fmt, ap);
> +	va_end(ap);
> +
> +	if (ret < 0) {
> +		if (err && !*err)
> +			*err = ret;
> +	} else {
> +		*buf_p += ret;
> +		*blen -= ret;
> +	}
> +
> +	return ret;
> +}

So this now implements the old behaviour of ignoring previous errors, in
all cases, since we don't check for errors and bail out in the callers.

If you simply check for validity of err and for it being 0 before
proceeding with the va_start() above, this should be fixed.

Cheers,
Andre

> +
>  int arm_spe_pkt_desc(const struct arm_spe_pkt *packet, char *buf,
>  		     size_t buf_len)
>  {
> -	int ret, ns, el, idx = packet->index;
> +	int ns, el, idx = packet->index;
>  	unsigned long long payload = packet->payload;
>  	const char *name = arm_spe_pkt_name(packet->type);
> +	size_t blen = buf_len;
> +	int err = 0;
>  
>  	switch (packet->type) {
>  	case ARM_SPE_BAD:
>  	case ARM_SPE_PAD:
>  	case ARM_SPE_END:
> -		return snprintf(buf, buf_len, "%s", name);
> -	case ARM_SPE_EVENTS: {
> -		size_t blen = buf_len;
> -
> -		ret = 0;
> -		ret = snprintf(buf, buf_len, "EV");
> -		buf += ret;
> -		blen -= ret;
> -		if (payload & 0x1) {
> -			ret = snprintf(buf, buf_len, " EXCEPTION-GEN");
> -			buf += ret;
> -			blen -= ret;
> -		}
> -		if (payload & 0x2) {
> -			ret = snprintf(buf, buf_len, " RETIRED");
> -			buf += ret;
> -			blen -= ret;
> -		}
> -		if (payload & 0x4) {
> -			ret = snprintf(buf, buf_len, " L1D-ACCESS");
> -			buf += ret;
> -			blen -= ret;
> -		}
> -		if (payload & 0x8) {
> -			ret = snprintf(buf, buf_len, " L1D-REFILL");
> -			buf += ret;
> -			blen -= ret;
> -		}
> -		if (payload & 0x10) {
> -			ret = snprintf(buf, buf_len, " TLB-ACCESS");
> -			buf += ret;
> -			blen -= ret;
> -		}
> -		if (payload & 0x20) {
> -			ret = snprintf(buf, buf_len, " TLB-REFILL");
> -			buf += ret;
> -			blen -= ret;
> -		}
> -		if (payload & 0x40) {
> -			ret = snprintf(buf, buf_len, " NOT-TAKEN");
> -			buf += ret;
> -			blen -= ret;
> -		}
> -		if (payload & 0x80) {
> -			ret = snprintf(buf, buf_len, " MISPRED");
> -			buf += ret;
> -			blen -= ret;
> -		}
> +		return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s", name);
> +	case ARM_SPE_EVENTS:
> +		arm_spe_pkt_snprintf(&err, &buf, &blen, "EV");
> +
> +		if (payload & 0x1)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCEPTION-GEN");
> +		if (payload & 0x2)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " RETIRED");
> +		if (payload & 0x4)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-ACCESS");
> +		if (payload & 0x8)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-REFILL");
> +		if (payload & 0x10)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-ACCESS");
> +		if (payload & 0x20)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-REFILL");
> +		if (payload & 0x40)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " NOT-TAKEN");
> +		if (payload & 0x80)
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, " MISPRED");
>  		if (idx > 1) {
> -			if (payload & 0x100) {
> -				ret = snprintf(buf, buf_len, " LLC-ACCESS");
> -				buf += ret;
> -				blen -= ret;
> -			}
> -			if (payload & 0x200) {
> -				ret = snprintf(buf, buf_len, " LLC-REFILL");
> -				buf += ret;
> -				blen -= ret;
> -			}
> -			if (payload & 0x400) {
> -				ret = snprintf(buf, buf_len, " REMOTE-ACCESS");
> -				buf += ret;
> -				blen -= ret;
> -			}
> +			if (payload & 0x100)
> +				arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-ACCESS");
> +			if (payload & 0x200)
> +				arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-REFILL");
> +			if (payload & 0x400)
> +				arm_spe_pkt_snprintf(&err, &buf, &blen, " REMOTE-ACCESS");
>  		}
> -		if (ret < 0)
> -			return ret;
> -		blen -= ret;
> -		return buf_len - blen;
> -	}
> +		return err ?: (int)(buf_len - blen);
> +
>  	case ARM_SPE_OP_TYPE:
>  		switch (idx) {
> -		case 0:	return snprintf(buf, buf_len, "%s", payload & 0x1 ?
> -					"COND-SELECT" : "INSN-OTHER");
> -		case 1:	{
> -			size_t blen = buf_len;
> +		case 0:
> +			return arm_spe_pkt_snprintf(&err, &buf, &blen,
> +					payload & 0x1 ? "COND-SELECT" : "INSN-OTHER");
> +		case 1:
> +			arm_spe_pkt_snprintf(&err, &buf, &blen,
> +					     payload & 0x1 ? "ST" : "LD");
>  
> -			if (payload & 0x1)
> -				ret = snprintf(buf, buf_len, "ST");
> -			else
> -				ret = snprintf(buf, buf_len, "LD");
> -			buf += ret;
> -			blen -= ret;
>  			if (payload & 0x2) {
> -				if (payload & 0x4) {
> -					ret = snprintf(buf, buf_len, " AT");
> -					buf += ret;
> -					blen -= ret;
> -				}
> -				if (payload & 0x8) {
> -					ret = snprintf(buf, buf_len, " EXCL");
> -					buf += ret;
> -					blen -= ret;
> -				}
> -				if (payload & 0x10) {
> -					ret = snprintf(buf, buf_len, " AR");
> -					buf += ret;
> -					blen -= ret;
> -				}
> +				if (payload & 0x4)
> +					arm_spe_pkt_snprintf(&err, &buf, &blen, " AT");
> +				if (payload & 0x8)
> +					arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCL");
> +				if (payload & 0x10)
> +					arm_spe_pkt_snprintf(&err, &buf, &blen, " AR");
>  			} else if (payload & 0x4) {
> -				ret = snprintf(buf, buf_len, " SIMD-FP");
> -				buf += ret;
> -				blen -= ret;
> -			}
> -			if (ret < 0)
> -				return ret;
> -			blen -= ret;
> -			return buf_len - blen;
> -		}
> -		case 2:	{
> -			size_t blen = buf_len;
> -
> -			ret = snprintf(buf, buf_len, "B");
> -			buf += ret;
> -			blen -= ret;
> -			if (payload & 0x1) {
> -				ret = snprintf(buf, buf_len, " COND");
> -				buf += ret;
> -				blen -= ret;
> -			}
> -			if (payload & 0x2) {
> -				ret = snprintf(buf, buf_len, " IND");
> -				buf += ret;
> -				blen -= ret;
> +				arm_spe_pkt_snprintf(&err, &buf, &blen, " SIMD-FP");
>  			}
> -			if (ret < 0)
> -				return ret;
> -			blen -= ret;
> -			return buf_len - blen;
> -			}
> -		default: return 0;
> +
> +			return err ?: (int)(buf_len - blen);
> +
> +		case 2:
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, "B");
> +
> +			if (payload & 0x1)
> +				arm_spe_pkt_snprintf(&err, &buf, &blen, " COND");
> +			if (payload & 0x2)
> +				arm_spe_pkt_snprintf(&err, &buf, &blen, " IND");
> +
> +			return err ?: (int)(buf_len - blen);
> +
> +		default:
> +			return 0;
>  		}
>  	case ARM_SPE_DATA_SOURCE:
>  	case ARM_SPE_TIMESTAMP:
> -		return snprintf(buf, buf_len, "%s %lld", name, payload);
> +		return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %lld", name, payload);
>  	case ARM_SPE_ADDRESS:
>  		switch (idx) {
>  		case 0:
>  		case 1: ns = !!(packet->payload & NS_FLAG);
>  			el = (packet->payload & EL_FLAG) >> 61;
>  			payload &= ~(0xffULL << 56);
> -			return snprintf(buf, buf_len, "%s 0x%llx el%d ns=%d",
> +			return arm_spe_pkt_snprintf(&err, &buf, &blen,
> +					"%s 0x%llx el%d ns=%d",
>  				        (idx == 1) ? "TGT" : "PC", payload, el, ns);
> -		case 2:	return snprintf(buf, buf_len, "VA 0x%llx", payload);
> +		case 2:
> +			return arm_spe_pkt_snprintf(&err, &buf, &blen,
> +						    "VA 0x%llx", payload);
>  		case 3:	ns = !!(packet->payload & NS_FLAG);
>  			payload &= ~(0xffULL << 56);
> -			return snprintf(buf, buf_len, "PA 0x%llx ns=%d",
> -					payload, ns);
> -		default: return 0;
> +			return arm_spe_pkt_snprintf(&err, &buf, &blen,
> +						    "PA 0x%llx ns=%d", payload, ns);
> +		default:
> +			return 0;
>  		}
>  	case ARM_SPE_CONTEXT:
> -		return snprintf(buf, buf_len, "%s 0x%lx el%d", name,
> -				(unsigned long)payload, idx + 1);
> -	case ARM_SPE_COUNTER: {
> -		size_t blen = buf_len;
> -
> -		ret = snprintf(buf, buf_len, "%s %d ", name,
> -			       (unsigned short)payload);
> -		buf += ret;
> -		blen -= ret;
> +		return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s 0x%lx el%d",
> +					    name, (unsigned long)payload, idx + 1);
> +	case ARM_SPE_COUNTER:
> +		arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %d ", name,
> +				     (unsigned short)payload);
> +
>  		switch (idx) {
> -		case 0:	ret = snprintf(buf, buf_len, "TOT"); break;
> -		case 1:	ret = snprintf(buf, buf_len, "ISSUE"); break;
> -		case 2:	ret = snprintf(buf, buf_len, "XLAT"); break;
> -		default: ret = 0;
> +		case 0:
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, "TOT");
> +			break;
> +		case 1:
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, "ISSUE");
> +			break;
> +		case 2:
> +			arm_spe_pkt_snprintf(&err, &buf, &blen, "XLAT");
> +			break;
> +		default:
> +			break;
>  		}
> -		if (ret < 0)
> -			return ret;
> -		blen -= ret;
> -		return buf_len - blen;
> -	}
> +
> +		return err ?: (int)(buf_len - blen);
> +
>  	default:
>  		break;
>  	}
>  
> -	return snprintf(buf, buf_len, "%s 0x%llx (%d)",
> -			name, payload, packet->index);
> +	return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s 0x%llx (%d)",
> +				    name, payload, packet->index);
>  }
>
Leo Yan Oct. 29, 2020, 10:51 a.m. UTC | #2
Hi Andre,

On Thu, Oct 29, 2020 at 10:23:39AM +0000, André Przywara wrote:

[...]

> > +static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> > +				const char *fmt, ...)
> > +{
> > +	va_list ap;
> > +	int ret;
> > +
> > +	va_start(ap, fmt);
> > +	ret = vsnprintf(*buf_p, *blen, fmt, ap);
> > +	va_end(ap);
> > +
> > +	if (ret < 0) {
> > +		if (err && !*err)
> > +			*err = ret;
> > +	} else {
> > +		*buf_p += ret;
> > +		*blen -= ret;
> > +	}
> > +
> > +	return ret;
> > +}
> 
> So this now implements the old behaviour of ignoring previous errors, in
> all cases, since we don't check for errors and bail out in the callers.
> 
> If you simply check for validity of err and for it being 0 before
> proceeding with the va_start() above, this should be fixed.

I think you are suggesting below code, could you take a look for it
before I proceed to respin new patch?

static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
				const char *fmt, ...)
{
	va_list ap;
	int ret;

        /* Bail out if any error occurred */
        if (err && *err)
                return *err;

	va_start(ap, fmt);
	ret = vsnprintf(*buf_p, *blen, fmt, ap);
	va_end(ap);

	if (ret < 0) {
		if (err && !*err)
			*err = ret;
	} else {
		*buf_p += ret;
		*blen -= ret;
	}

	return ret;
}

Thanks,
Leo
André Przywara Oct. 29, 2020, 10:54 a.m. UTC | #3
On 29/10/2020 10:51, Leo Yan wrote:
> Hi Andre,
> 
> On Thu, Oct 29, 2020 at 10:23:39AM +0000, Andr� Przywara wrote:
> 
> [...]
> 
>>> +static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
>>> +				const char *fmt, ...)
>>> +{
>>> +	va_list ap;
>>> +	int ret;
>>> +
>>> +	va_start(ap, fmt);
>>> +	ret = vsnprintf(*buf_p, *blen, fmt, ap);
>>> +	va_end(ap);
>>> +
>>> +	if (ret < 0) {
>>> +		if (err && !*err)
>>> +			*err = ret;
>>> +	} else {
>>> +		*buf_p += ret;
>>> +		*blen -= ret;
>>> +	}
>>> +
>>> +	return ret;
>>> +}
>>
>> So this now implements the old behaviour of ignoring previous errors, in
>> all cases, since we don't check for errors and bail out in the callers.
>>
>> If you simply check for validity of err and for it being 0 before
>> proceeding with the va_start() above, this should be fixed.
> 
> I think you are suggesting below code, could you take a look for it
> before I proceed to respin new patch?>
> static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> 				const char *fmt, ...)
> {
> 	va_list ap;
> 	int ret;
> 
>         /* Bail out if any error occurred */
>         if (err && *err)
>                 return *err;
> 
> 	va_start(ap, fmt);
> 	ret = vsnprintf(*buf_p, *blen, fmt, ap);
> 	va_end(ap);
> 
> 	if (ret < 0) {
> 		if (err && !*err)
> 			*err = ret;
> 	} else {
> 		*buf_p += ret;
> 		*blen -= ret;
> 	}
> 
> 	return ret;
> }

Yes, this is what I had in mind.

Cheers,
Andre
Leo Yan Oct. 29, 2020, 11:06 a.m. UTC | #4
On Thu, Oct 29, 2020 at 10:54:37AM +0000, André Przywara wrote:
> On 29/10/2020 10:51, Leo Yan wrote:
> > Hi Andre,
> > 
> > On Thu, Oct 29, 2020 at 10:23:39AM +0000, Andr� Przywara wrote:
> > 
> > [...]
> > 
> >>> +static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> >>> +				const char *fmt, ...)
> >>> +{
> >>> +	va_list ap;
> >>> +	int ret;
> >>> +
> >>> +	va_start(ap, fmt);
> >>> +	ret = vsnprintf(*buf_p, *blen, fmt, ap);
> >>> +	va_end(ap);
> >>> +
> >>> +	if (ret < 0) {
> >>> +		if (err && !*err)
> >>> +			*err = ret;
> >>> +	} else {
> >>> +		*buf_p += ret;
> >>> +		*blen -= ret;
> >>> +	}
> >>> +
> >>> +	return ret;
> >>> +}
> >>
> >> So this now implements the old behaviour of ignoring previous errors, in
> >> all cases, since we don't check for errors and bail out in the callers.
> >>
> >> If you simply check for validity of err and for it being 0 before
> >> proceeding with the va_start() above, this should be fixed.
> > 
> > I think you are suggesting below code, could you take a look for it
> > before I proceed to respin new patch?>
> > static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> > 				const char *fmt, ...)
> > {
> > 	va_list ap;
> > 	int ret;
> > 
> >         /* Bail out if any error occurred */
> >         if (err && *err)
> >                 return *err;
> > 
> > 	va_start(ap, fmt);
> > 	ret = vsnprintf(*buf_p, *blen, fmt, ap);
> > 	va_end(ap);
> > 
> > 	if (ret < 0) {
> > 		if (err && !*err)
> > 			*err = ret;
> > 	} else {
> > 		*buf_p += ret;
> > 		*blen -= ret;
> > 	}
> > 
> > 	return ret;
> > }
> 
> Yes, this is what I had in mind.

Thanks for confirmation, Andre.

Leo

Patch
diff mbox series

diff --git a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
index 04fd7fd7c15f..9147b88ae00c 100644
--- a/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
+++ b/tools/perf/util/arm-spe-decoder/arm-spe-pkt-decoder.c
@@ -9,6 +9,7 @@ 
 #include <endian.h>
 #include <byteswap.h>
 #include <linux/bitops.h>
+#include <stdarg.h>
 
 #include "arm-spe-pkt-decoder.h"
 
@@ -258,192 +259,154 @@  int arm_spe_get_packet(const unsigned char *buf, size_t len,
 	return ret;
 }
 
+static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
+				const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	va_start(ap, fmt);
+	ret = vsnprintf(*buf_p, *blen, fmt, ap);
+	va_end(ap);
+
+	if (ret < 0) {
+		if (err && !*err)
+			*err = ret;
+	} else {
+		*buf_p += ret;
+		*blen -= ret;
+	}
+
+	return ret;
+}
+
 int arm_spe_pkt_desc(const struct arm_spe_pkt *packet, char *buf,
 		     size_t buf_len)
 {
-	int ret, ns, el, idx = packet->index;
+	int ns, el, idx = packet->index;
 	unsigned long long payload = packet->payload;
 	const char *name = arm_spe_pkt_name(packet->type);
+	size_t blen = buf_len;
+	int err = 0;
 
 	switch (packet->type) {
 	case ARM_SPE_BAD:
 	case ARM_SPE_PAD:
 	case ARM_SPE_END:
-		return snprintf(buf, buf_len, "%s", name);
-	case ARM_SPE_EVENTS: {
-		size_t blen = buf_len;
-
-		ret = 0;
-		ret = snprintf(buf, buf_len, "EV");
-		buf += ret;
-		blen -= ret;
-		if (payload & 0x1) {
-			ret = snprintf(buf, buf_len, " EXCEPTION-GEN");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x2) {
-			ret = snprintf(buf, buf_len, " RETIRED");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x4) {
-			ret = snprintf(buf, buf_len, " L1D-ACCESS");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x8) {
-			ret = snprintf(buf, buf_len, " L1D-REFILL");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x10) {
-			ret = snprintf(buf, buf_len, " TLB-ACCESS");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x20) {
-			ret = snprintf(buf, buf_len, " TLB-REFILL");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x40) {
-			ret = snprintf(buf, buf_len, " NOT-TAKEN");
-			buf += ret;
-			blen -= ret;
-		}
-		if (payload & 0x80) {
-			ret = snprintf(buf, buf_len, " MISPRED");
-			buf += ret;
-			blen -= ret;
-		}
+		return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s", name);
+	case ARM_SPE_EVENTS:
+		arm_spe_pkt_snprintf(&err, &buf, &blen, "EV");
+
+		if (payload & 0x1)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCEPTION-GEN");
+		if (payload & 0x2)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " RETIRED");
+		if (payload & 0x4)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-ACCESS");
+		if (payload & 0x8)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-REFILL");
+		if (payload & 0x10)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-ACCESS");
+		if (payload & 0x20)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-REFILL");
+		if (payload & 0x40)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " NOT-TAKEN");
+		if (payload & 0x80)
+			arm_spe_pkt_snprintf(&err, &buf, &blen, " MISPRED");
 		if (idx > 1) {
-			if (payload & 0x100) {
-				ret = snprintf(buf, buf_len, " LLC-ACCESS");
-				buf += ret;
-				blen -= ret;
-			}
-			if (payload & 0x200) {
-				ret = snprintf(buf, buf_len, " LLC-REFILL");
-				buf += ret;
-				blen -= ret;
-			}
-			if (payload & 0x400) {
-				ret = snprintf(buf, buf_len, " REMOTE-ACCESS");
-				buf += ret;
-				blen -= ret;
-			}
+			if (payload & 0x100)
+				arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-ACCESS");
+			if (payload & 0x200)
+				arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-REFILL");
+			if (payload & 0x400)
+				arm_spe_pkt_snprintf(&err, &buf, &blen, " REMOTE-ACCESS");
 		}
-		if (ret < 0)
-			return ret;
-		blen -= ret;
-		return buf_len - blen;
-	}
+		return err ?: (int)(buf_len - blen);
+
 	case ARM_SPE_OP_TYPE:
 		switch (idx) {
-		case 0:	return snprintf(buf, buf_len, "%s", payload & 0x1 ?
-					"COND-SELECT" : "INSN-OTHER");
-		case 1:	{
-			size_t blen = buf_len;
+		case 0:
+			return arm_spe_pkt_snprintf(&err, &buf, &blen,
+					payload & 0x1 ? "COND-SELECT" : "INSN-OTHER");
+		case 1:
+			arm_spe_pkt_snprintf(&err, &buf, &blen,
+					     payload & 0x1 ? "ST" : "LD");
 
-			if (payload & 0x1)
-				ret = snprintf(buf, buf_len, "ST");
-			else
-				ret = snprintf(buf, buf_len, "LD");
-			buf += ret;
-			blen -= ret;
 			if (payload & 0x2) {
-				if (payload & 0x4) {
-					ret = snprintf(buf, buf_len, " AT");
-					buf += ret;
-					blen -= ret;
-				}
-				if (payload & 0x8) {
-					ret = snprintf(buf, buf_len, " EXCL");
-					buf += ret;
-					blen -= ret;
-				}
-				if (payload & 0x10) {
-					ret = snprintf(buf, buf_len, " AR");
-					buf += ret;
-					blen -= ret;
-				}
+				if (payload & 0x4)
+					arm_spe_pkt_snprintf(&err, &buf, &blen, " AT");
+				if (payload & 0x8)
+					arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCL");
+				if (payload & 0x10)
+					arm_spe_pkt_snprintf(&err, &buf, &blen, " AR");
 			} else if (payload & 0x4) {
-				ret = snprintf(buf, buf_len, " SIMD-FP");
-				buf += ret;
-				blen -= ret;
-			}
-			if (ret < 0)
-				return ret;
-			blen -= ret;
-			return buf_len - blen;
-		}
-		case 2:	{
-			size_t blen = buf_len;
-
-			ret = snprintf(buf, buf_len, "B");
-			buf += ret;
-			blen -= ret;
-			if (payload & 0x1) {
-				ret = snprintf(buf, buf_len, " COND");
-				buf += ret;
-				blen -= ret;
-			}
-			if (payload & 0x2) {
-				ret = snprintf(buf, buf_len, " IND");
-				buf += ret;
-				blen -= ret;
+				arm_spe_pkt_snprintf(&err, &buf, &blen, " SIMD-FP");
 			}
-			if (ret < 0)
-				return ret;
-			blen -= ret;
-			return buf_len - blen;
-			}
-		default: return 0;
+
+			return err ?: (int)(buf_len - blen);
+
+		case 2:
+			arm_spe_pkt_snprintf(&err, &buf, &blen, "B");
+
+			if (payload & 0x1)
+				arm_spe_pkt_snprintf(&err, &buf, &blen, " COND");
+			if (payload & 0x2)
+				arm_spe_pkt_snprintf(&err, &buf, &blen, " IND");
+
+			return err ?: (int)(buf_len - blen);
+
+		default:
+			return 0;
 		}
 	case ARM_SPE_DATA_SOURCE:
 	case ARM_SPE_TIMESTAMP:
-		return snprintf(buf, buf_len, "%s %lld", name, payload);
+		return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %lld", name, payload);
 	case ARM_SPE_ADDRESS:
 		switch (idx) {
 		case 0:
 		case 1: ns = !!(packet->payload & NS_FLAG);
 			el = (packet->payload & EL_FLAG) >> 61;
 			payload &= ~(0xffULL << 56);
-			return snprintf(buf, buf_len, "%s 0x%llx el%d ns=%d",
+			return arm_spe_pkt_snprintf(&err, &buf, &blen,
+					"%s 0x%llx el%d ns=%d",
 				        (idx == 1) ? "TGT" : "PC", payload, el, ns);
-		case 2:	return snprintf(buf, buf_len, "VA 0x%llx", payload);
+		case 2:
+			return arm_spe_pkt_snprintf(&err, &buf, &blen,
+						    "VA 0x%llx", payload);
 		case 3:	ns = !!(packet->payload & NS_FLAG);
 			payload &= ~(0xffULL << 56);
-			return snprintf(buf, buf_len, "PA 0x%llx ns=%d",
-					payload, ns);
-		default: return 0;
+			return arm_spe_pkt_snprintf(&err, &buf, &blen,
+						    "PA 0x%llx ns=%d", payload, ns);
+		default:
+			return 0;
 		}
 	case ARM_SPE_CONTEXT:
-		return snprintf(buf, buf_len, "%s 0x%lx el%d", name,
-				(unsigned long)payload, idx + 1);
-	case ARM_SPE_COUNTER: {
-		size_t blen = buf_len;
-
-		ret = snprintf(buf, buf_len, "%s %d ", name,
-			       (unsigned short)payload);
-		buf += ret;
-		blen -= ret;
+		return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s 0x%lx el%d",
+					    name, (unsigned long)payload, idx + 1);
+	case ARM_SPE_COUNTER:
+		arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %d ", name,
+				     (unsigned short)payload);
+
 		switch (idx) {
-		case 0:	ret = snprintf(buf, buf_len, "TOT"); break;
-		case 1:	ret = snprintf(buf, buf_len, "ISSUE"); break;
-		case 2:	ret = snprintf(buf, buf_len, "XLAT"); break;
-		default: ret = 0;
+		case 0:
+			arm_spe_pkt_snprintf(&err, &buf, &blen, "TOT");
+			break;
+		case 1:
+			arm_spe_pkt_snprintf(&err, &buf, &blen, "ISSUE");
+			break;
+		case 2:
+			arm_spe_pkt_snprintf(&err, &buf, &blen, "XLAT");
+			break;
+		default:
+			break;
 		}
-		if (ret < 0)
-			return ret;
-		blen -= ret;
-		return buf_len - blen;
-	}
+
+		return err ?: (int)(buf_len - blen);
+
 	default:
 		break;
 	}
 
-	return snprintf(buf, buf_len, "%s 0x%llx (%d)",
-			name, payload, packet->index);
+	return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s 0x%llx (%d)",
+				    name, payload, packet->index);
 }