From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52C51C388F9 for ; Wed, 11 Nov 2020 16:04:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C95942072C for ; Wed, 11 Nov 2020 16:04:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726553AbgKKQEh (ORCPT ); Wed, 11 Nov 2020 11:04:37 -0500 Received: from foss.arm.com ([217.140.110.172]:57100 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725867AbgKKQEh (ORCPT ); Wed, 11 Nov 2020 11:04:37 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 05928101E; Wed, 11 Nov 2020 08:04:36 -0800 (PST) Received: from arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 05E623F6CF; Wed, 11 Nov 2020 08:04:33 -0800 (PST) Date: Wed, 11 Nov 2020 16:04:30 +0000 From: Dave Martin To: Leo Yan Cc: Arnaldo Carvalho de Melo , Andre Przywara , James Clark , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Al Grant , Wei Li , John Garry , Will Deacon , Mathieu Poirier , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH v8 07/22] perf arm-spe: Consolidate arm_spe_pkt_desc()'s return value Message-ID: <20201111160429.GO6882@arm.com> References: <20201111071149.815-1-leo.yan@linaro.org> <20201111071149.815-8-leo.yan@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201111071149.815-8-leo.yan@linaro.org> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 11, 2020 at 07:11:34AM +0000, 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(). > > This patch changes the caller arm_spe_dump() to respect the updated > return value semantics of arm_spe_pkt_desc(). > > Suggested-by: Dave Martin > Signed-off-by: Leo Yan > Reviewed-by: Andre Przywara > --- > .../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..424ff5862aa1 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, &buf_len, "%s 0x%llx (%d)", > + name, payload, packet->index); > + } > + > + return err; Ah, I understand what this is doing now. Thanks for the extra comment. > } > 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); The effect of this patch looks OK to me, so Reviewed-by: Dave Martin [...] Cheers ---Dave