From: "André Przywara" <andre.przywara@arm.com>
To: Leo Yan <leo.yan@linaro.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Dave Martin <Dave.Martin@arm.com>,
James Clark <james.clark@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Al Grant <Al.Grant@arm.com>, Wei Li <liwei391@huawei.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 07/22] perf arm-spe: Consolidate arm_spe_pkt_desc()'s return value
Date: Mon, 9 Nov 2020 16:52:35 +0000 [thread overview]
Message-ID: <478837ab-5477-ef17-fe6a-6ea24311d904@arm.com> (raw)
In-Reply-To: <20201106014136.14103-8-leo.yan@linaro.org>
On 06/11/2020 01:41, Leo Yan wrote:
> arm_spe_pkt_desc() returns the length of consumed the buffer for
> the success case; otherwise, it delivers the return value from
> arm_spe_pkt_snprintf(), and returns the last return value if there have
> multiple calling arm_spe_pkt_snprintf().
>
> Since arm_spe_pkt_snprintf() has the same semantics with vsnprintf() for
> the return value, and vsnprintf() might return value equals to or bigger
> than the parameter 'size' to indicate the truncation. Because the
> return value is >= 0 when the string is truncated, this condition will
> be returned up the stack as "success".
>
> This patch simplifies the return value for arm_spe_pkt_desc(): '0' means
> success and other values mean an error has occurred. To realize this,
> it relies on arm_spe_pkt_snprintf()'s parameter 'err', the 'err' is a
> cumulative value, returns its final value if printing buffer is called
> for one time or multiple times.
>
> To unify the error value generation, this patch handles error in a
> central place, rather than directly bailing out in switch-cases,
> it returns error at the end of arm_spe_pkt_desc().
And the but-last hunk means it will basically always return 0?
Just checking, it's probably fine (and I don't want to review a v8 ;-)
> This patch changes the caller arm_spe_dump() to respect the updated
> return value semantics of arm_spe_pkt_desc().
>
> Suggested-by: Dave Martin <Dave.Martin@arm.com>
> Signed-off-by: Leo Yan <leo.yan@linaro.org>
One tiny thing below ...
> ---
> .../arm-spe-decoder/arm-spe-pkt-decoder.c | 128 +++++++++---------
> tools/perf/util/arm-spe.c | 2 +-
> 2 files changed, 68 insertions(+), 62 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 1970686f7020..33baef0c2c0b 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
> @@ -301,9 +301,10 @@ static int arm_spe_pkt_snprintf(int *err, char **buf_p, size_t *blen,
> 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);
> + char *buf_orig = buf;
> size_t blen = buf_len;
> int err = 0;
>
> @@ -311,82 +312,76 @@ int arm_spe_pkt_desc(const struct arm_spe_pkt *packet, char *buf,
> case ARM_SPE_BAD:
> case ARM_SPE_PAD:
> case ARM_SPE_END:
> - return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s", name);
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "%s", name);
> + break;
> case ARM_SPE_EVENTS:
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, "EV");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "EV");
>
> if (payload & 0x1)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCEPTION-GEN");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCEPTION-GEN");
> if (payload & 0x2)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " RETIRED");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " RETIRED");
> if (payload & 0x4)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-ACCESS");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-ACCESS");
> if (payload & 0x8)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-REFILL");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " L1D-REFILL");
> if (payload & 0x10)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-ACCESS");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-ACCESS");
> if (payload & 0x20)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-REFILL");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " TLB-REFILL");
> if (payload & 0x40)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " NOT-TAKEN");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " NOT-TAKEN");
> if (payload & 0x80)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " MISPRED");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " MISPRED");
> if (idx > 1) {
> if (payload & 0x100)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-ACCESS");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-ACCESS");
> if (payload & 0x200)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-REFILL");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " LLC-REFILL");
> if (payload & 0x400)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " REMOTE-ACCESS");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " REMOTE-ACCESS");
> }
> - if (ret < 0)
> - return ret;
> - blen -= ret;
> - return buf_len - blen;
> + break;
> case ARM_SPE_OP_TYPE:
> switch (idx) {
> case 0:
> - return arm_spe_pkt_snprintf(&err, &buf, &blen,
> + arm_spe_pkt_snprintf(&err, &buf, &blen,
> payload & 0x1 ? "COND-SELECT" : "INSN-OTHER");
> + break;
> case 1:
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen,
> - payload & 0x1 ? "ST" : "LD");
> + arm_spe_pkt_snprintf(&err, &buf, &blen,
> + payload & 0x1 ? "ST" : "LD");
>
> if (payload & 0x2) {
> if (payload & 0x4)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " AT");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " AT");
> if (payload & 0x8)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCL");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " EXCL");
> if (payload & 0x10)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " AR");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " AR");
> } else if (payload & 0x4) {
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " SIMD-FP");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " SIMD-FP");
> }
> -
> - if (ret < 0)
> - return ret;
> - blen -= ret;
> - return buf_len - blen;
> -
> + break;
> case 2:
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, "B");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "B");
>
> if (payload & 0x1)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " COND");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " COND");
> if (payload & 0x2)
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, " IND");
> -
> - if (ret < 0)
> - return ret;
> - blen -= ret;
> - return buf_len - blen;
> + arm_spe_pkt_snprintf(&err, &buf, &blen, " IND");
>
> + break;
> default:
> - return 0;
> + /* Unknown index */
> + err = -1;
> + break;
> }
> + break;
> case ARM_SPE_DATA_SOURCE:
> case ARM_SPE_TIMESTAMP:
> - return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %lld", name, payload);
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %lld", name, payload);
> + break;
> case ARM_SPE_ADDRESS:
> switch (idx) {
> case 0:
> @@ -394,48 +389,59 @@ int arm_spe_pkt_desc(const struct arm_spe_pkt *packet, char *buf,
> ns = !!(packet->payload & NS_FLAG);
> el = (packet->payload & EL_FLAG) >> 61;
> payload &= ~(0xffULL << 56);
> - return arm_spe_pkt_snprintf(&err, &buf, &blen,
> + arm_spe_pkt_snprintf(&err, &buf, &blen,
> "%s 0x%llx el%d ns=%d",
> (idx == 1) ? "TGT" : "PC", payload, el, ns);
> + break;
> case 2:
> - return arm_spe_pkt_snprintf(&err, &buf, &blen,
> - "VA 0x%llx", payload);
> + arm_spe_pkt_snprintf(&err, &buf, &blen,
> + "VA 0x%llx", payload);
> + break;
> case 3:
> ns = !!(packet->payload & NS_FLAG);
> payload &= ~(0xffULL << 56);
> - return arm_spe_pkt_snprintf(&err, &buf, &blen,
> - "PA 0x%llx ns=%d", payload, ns);
> + arm_spe_pkt_snprintf(&err, &buf, &blen,
> + "PA 0x%llx ns=%d", payload, ns);
> + break;
> default:
> - return 0;
> + /* Unknown index */
> + err = -1;
> + break;
> }
> + break;
> case ARM_SPE_CONTEXT:
> - return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s 0x%lx el%d",
> - name, (unsigned long)payload, idx + 1);
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "%s 0x%lx el%d",
> + name, (unsigned long)payload, idx + 1);
> + break;
> case ARM_SPE_COUNTER:
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %d ", name,
> - (unsigned short)payload);
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "%s %d ", name,
> + (unsigned short)payload);
> switch (idx) {
> case 0:
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, "TOT");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "TOT");
> break;
> case 1:
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, "ISSUE");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "ISSUE");
> break;
> case 2:
> - ret = arm_spe_pkt_snprintf(&err, &buf, &blen, "XLAT");
> + arm_spe_pkt_snprintf(&err, &buf, &blen, "XLAT");
> break;
> default:
> - ret = 0;
> break;
> }
> - if (ret < 0)
> - return ret;
> - blen -= ret;
> - return buf_len - blen;
> + break;
> default:
> + /* Unknown index */
> + err = -1;
> break;
> }
>
> - return arm_spe_pkt_snprintf(&err, &buf, &blen, "%s 0x%llx (%d)",
> - name, payload, packet->index);
> + /* Output raw data if detect any error */
> + if (err) {
> + err = 0;
> + arm_spe_pkt_snprintf(&err, &buf_orig, &blen, "%s 0x%llx (%d)",
That needs to be &buf_len here, doesn't it?
With that fixed:
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Cheers,
Andre
> + name, payload, packet->index);
> + }
> +
> + return err;
> }
> diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
> index 3882a5360ada..8901a1656a41 100644
> --- a/tools/perf/util/arm-spe.c
> +++ b/tools/perf/util/arm-spe.c
> @@ -113,7 +113,7 @@ static void arm_spe_dump(struct arm_spe *spe __maybe_unused,
> if (ret > 0) {
> ret = arm_spe_pkt_desc(&packet, desc,
> ARM_SPE_PKT_DESC_MAX);
> - if (ret > 0)
> + if (!ret)
> color_fprintf(stdout, color, " %s\n", desc);
> } else {
> color_fprintf(stdout, color, " Bad packet!\n");
>
next prev parent reply other threads:[~2020-11-09 16:52 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-06 1:41 [PATCH v7 00/22] perf arm-spe: Refactor decoding & dumping flow Leo Yan
2020-11-06 1:41 ` [PATCH v7 01/22] perf arm-spe: Include bitops.h for BIT() macro Leo Yan
2020-11-06 1:41 ` [PATCH v7 02/22] perf arm-spe: Fix a typo in comment Leo Yan
2020-11-06 1:41 ` [PATCH v7 03/22] perf arm-spe: Refactor payload size calculation Leo Yan
2020-11-06 1:41 ` [PATCH v7 04/22] perf arm-spe: Refactor arm_spe_get_events() Leo Yan
2020-11-06 1:41 ` [PATCH v7 05/22] perf arm-spe: Fix packet length handling Leo Yan
2020-11-06 1:41 ` [PATCH v7 06/22] perf arm-spe: Refactor printing string to buffer Leo Yan
2020-11-09 12:58 ` André Przywara
2020-11-06 1:41 ` [PATCH v7 07/22] perf arm-spe: Consolidate arm_spe_pkt_desc()'s return value Leo Yan
2020-11-09 16:52 ` André Przywara [this message]
2020-11-10 10:22 ` Leo Yan
2020-11-06 1:41 ` [PATCH v7 08/22] perf arm-spe: Refactor packet header parsing Leo Yan
2020-11-06 1:41 ` [PATCH v7 09/22] perf arm-spe: Add new function arm_spe_pkt_desc_addr() Leo Yan
2020-11-06 1:41 ` [PATCH v7 10/22] perf arm-spe: Refactor address packet handling Leo Yan
2020-11-06 1:41 ` [PATCH v7 11/22] perf arm_spe: Fixup top byte for data virtual address Leo Yan
2020-11-06 1:41 ` [PATCH v7 12/22] perf arm-spe: Refactor context packet handling Leo Yan
2020-11-06 1:41 ` [PATCH v7 13/22] perf arm-spe: Add new function arm_spe_pkt_desc_counter() Leo Yan
2020-11-06 1:41 ` [PATCH v7 14/22] perf arm-spe: Refactor counter packet handling Leo Yan
2020-11-06 1:41 ` [PATCH v7 15/22] perf arm-spe: Add new function arm_spe_pkt_desc_event() Leo Yan
2020-11-06 1:41 ` [PATCH v7 16/22] perf arm-spe: Refactor event type handling Leo Yan
2020-11-06 1:41 ` [PATCH v7 17/22] perf arm-spe: Remove size condition checking for events Leo Yan
2020-11-06 1:41 ` [PATCH v7 18/22] perf arm-spe: Add new function arm_spe_pkt_desc_op_type() Leo Yan
2020-11-06 1:41 ` [PATCH v7 19/22] perf arm-spe: Refactor operation packet handling Leo Yan
2020-11-06 1:41 ` [PATCH v7 20/22] perf arm-spe: Add more sub classes for operation packet Leo Yan
2020-11-06 1:41 ` [PATCH v7 21/22] perf arm_spe: Decode memory tagging properties Leo Yan
2020-11-06 1:41 ` [PATCH v7 22/22] perf arm-spe: Add support for ARMv8.3-SPE Leo Yan
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