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Tue, 3 Nov 2020 05:14:55 -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 15812139F; Tue, 3 Nov 2020 02:14:54 -0800 (PST) Received: from [192.168.2.22] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4791C3F66E; Tue, 3 Nov 2020 02:14:52 -0800 (PST) Subject: Re: [PATCH v6 06/21] perf arm-spe: Refactor printing string to buffer To: Leo Yan , Dave Martin Cc: Arnaldo Carvalho de Melo , Peter Zijlstra , Ingo Molnar , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , James Clark , Al Grant , Wei Li , "linux-kernel@vger.kernel.org" References: <20201030025724.19157-1-leo.yan@linaro.org> <20201030025724.19157-7-leo.yan@linaro.org> <20201102170653.GB6882@arm.com> <20201103064047.GD13232@leoy-ThinkPad-X240s> From: =?UTF-8?Q?Andr=c3=a9_Przywara?= Autocrypt: addr=andre.przywara@arm.com; prefer-encrypt=mutual; keydata= xsFNBFNPCKMBEAC+6GVcuP9ri8r+gg2fHZDedOmFRZPtcrMMF2Cx6KrTUT0YEISsqPoJTKld tPfEG0KnRL9CWvftyHseWTnU2Gi7hKNwhRkC0oBL5Er2hhNpoi8x4VcsxQ6bHG5/dA7ctvL6 kYvKAZw4X2Y3GTbAZIOLf+leNPiF9175S8pvqMPi0qu67RWZD5H/uT/TfLpvmmOlRzNiXMBm kGvewkBpL3R2clHquv7pB6KLoY3uvjFhZfEedqSqTwBVu/JVZZO7tvYCJPfyY5JG9+BjPmr+ REe2gS6w/4DJ4D8oMWKoY3r6ZpHx3YS2hWZFUYiCYovPxfj5+bOr78sg3JleEd0OB0yYtzTT esiNlQpCo0oOevwHR+jUiaZevM4xCyt23L2G+euzdRsUZcK/M6qYf41Dy6Afqa+PxgMEiDto ITEH3Dv+zfzwdeqCuNU0VOGrQZs/vrKOUmU/QDlYL7G8OIg5Ekheq4N+Ay+3EYCROXkstQnf YYxRn5F1oeVeqoh1LgGH7YN9H9LeIajwBD8OgiZDVsmb67DdF6EQtklH0ycBcVodG1zTCfqM AavYMfhldNMBg4vaLh0cJ/3ZXZNIyDlV372GmxSJJiidxDm7E1PkgdfCnHk+pD8YeITmSNyb 7qeU08Hqqh4ui8SSeUp7+yie9zBhJB5vVBJoO5D0MikZAODIDwARAQABzS1BbmRyZSBQcnp5 d2FyYSAoQVJNKSA8YW5kcmUucHJ6eXdhcmFAYXJtLmNvbT7CwXsEEwECACUCGwMGCwkIBwMC BhUIAgkKCwQWAgMBAh4BAheABQJTWSV8AhkBAAoJEAL1yD+ydue63REP/1tPqTo/f6StS00g NTUpjgVqxgsPWYWwSLkgkaUZn2z9Edv86BLpqTY8OBQZ19EUwfNehcnvR+Olw+7wxNnatyxo D2FG0paTia1SjxaJ8Nx3e85jy6l7N2AQrTCFCtFN9lp8Pc0LVBpSbjmP+Peh5Mi7gtCBNkpz KShEaJE25a/+rnIrIXzJHrsbC2GwcssAF3bd03iU41J1gMTalB6HCtQUwgqSsbG8MsR/IwHW XruOnVp0GQRJwlw07e9T3PKTLj3LWsAPe0LHm5W1Q+euoCLsZfYwr7phQ19HAxSCu8hzp43u zSw0+sEQsO+9wz2nGDgQCGepCcJR1lygVn2zwRTQKbq7Hjs+IWZ0gN2nDajScuR1RsxTE4WR lj0+Ne6VrAmPiW6QqRhliDO+e82riI75ywSWrJb9TQw0+UkIQ2DlNr0u0TwCUTcQNN6aKnru ouVt3qoRlcD5MuRhLH+ttAcmNITMg7GQ6RQajWrSKuKFrt6iuDbjgO2cnaTrLbNBBKPTG4oF D6kX8Zea0KvVBagBsaC1CDTDQQMxYBPDBSlqYCb/b2x7KHTvTAHUBSsBRL6MKz8wwruDodTM 4E4ToV9URl4aE/msBZ4GLTtEmUHBh4/AYwk6ACYByYKyx5r3PDG0iHnJ8bV0OeyQ9ujfgBBP B2t4oASNnIOeGEEcQ2rjzsFNBFNPCKMBEACm7Xqafb1Dp1nDl06aw/3O9ixWsGMv1Uhfd2B6 it6wh1HDCn9HpekgouR2HLMvdd3Y//GG89irEasjzENZPsK82PS0bvkxxIHRFm0pikF4ljIb 6tca2sxFr/H7CCtWYZjZzPgnOPtnagN0qVVyEM7L5f7KjGb1/o5EDkVR2SVSSjrlmNdTL2Rd zaPqrBoxuR/y/n856deWqS1ZssOpqwKhxT1IVlF6S47CjFJ3+fiHNjkljLfxzDyQXwXCNoZn BKcW9PvAMf6W1DGASoXtsMg4HHzZ5fW+vnjzvWiC4pXrcP7Ivfxx5pB+nGiOfOY+/VSUlW/9 GdzPlOIc1bGyKc6tGREH5lErmeoJZ5k7E9cMJx+xzuDItvnZbf6RuH5fg3QsljQy8jLlr4S6 8YwxlObySJ5K+suPRzZOG2+kq77RJVqAgZXp3Zdvdaov4a5J3H8pxzjj0yZ2JZlndM4X7Msr P5tfxy1WvV4Km6QeFAsjcF5gM+wWl+mf2qrlp3dRwniG1vkLsnQugQ4oNUrx0ahwOSm9p6kM CIiTITo+W7O9KEE9XCb4vV0ejmLlgdDV8ASVUekeTJkmRIBnz0fa4pa1vbtZoi6/LlIdAEEt PY6p3hgkLLtr2GRodOW/Y3vPRd9+rJHq/tLIfwc58ZhQKmRcgrhtlnuTGTmyUqGSiMNfpwAR AQABwsFfBBgBAgAJBQJTTwijAhsMAAoJEAL1yD+ydue64BgP/33QKczgAvSdj9XTC14wZCGE U8ygZwkkyNf021iNMj+o0dpLU48PIhHIMTXlM2aiiZlPWgKVlDRjlYuc9EZqGgbOOuR/pNYA JX9vaqszyE34JzXBL9DBKUuAui8z8GcxRcz49/xtzzP0kH3OQbBIqZWuMRxKEpRptRT0wzBL O31ygf4FRxs68jvPCuZjTGKELIo656/Hmk17cmjoBAJK7JHfqdGkDXk5tneeHCkB411p9WJU vMO2EqsHjobjuFm89hI0pSxlUoiTL0Nuk9Edemjw70W4anGNyaQtBq+qu1RdjUPBvoJec7y/ EXJtoGxq9Y+tmm22xwApSiIOyMwUi9A1iLjQLmngLeUdsHyrEWTbEYHd2sAM2sqKoZRyBDSv ejRvZD6zwkY/9nRqXt02H1quVOP42xlkwOQU6gxm93o/bxd7S5tEA359Sli5gZRaucpNQkwd KLQdCvFdksD270r4jU/rwR2R/Ubi+txfy0dk2wGBjl1xpSf0Lbl/KMR5TQntELfLR4etizLq Xpd2byn96Ivi8C8u9zJruXTueHH8vt7gJ1oax3yKRGU5o2eipCRiKZ0s/T7fvkdq+8beg9ku fDO4SAgJMIl6H5awliCY2zQvLHysS/Wb8QuB09hmhLZ4AifdHyF1J5qeePEhgTA+BaUbiUZf i4aIXCH3Wv6K Organization: ARM Ltd. Message-ID: <2b7d74c6-898c-75b1-338f-142bd62860c9@arm.com> Date: Tue, 3 Nov 2020 10:13:49 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201103064047.GD13232@leoy-ThinkPad-X240s> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/11/2020 06:40, Leo Yan wrote: Hi Dave, Leo, > On Mon, Nov 02, 2020 at 05:06:53PM +0000, Dave Martin wrote: >> On Fri, Oct 30, 2020 at 02:57:09AM +0000, Leo Yan wrote: >>> 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 >>> Signed-off-by: Leo Yan >> >> This looks like a good refacroting now, but as pointed out by Andre this >> patch is now rather hard to review, since it combines the refactoring >> with other changes. >> >> If reposting this series, it would be good if this could be split into a >> first patch that introduces arm_spe_pkt_snprintf() and just updates each >> snprintf() call site to use it, but without moving other code around or >> optimising anything, followed by one or more patches that clean up and >> simplify arm_spe_pkt_desc(). > > I will respin the patch set and follow this approach. Well, I am afraid this is not easily possible. Dave: this patch is basically following the pattern turning this: =============== if (condition) { ret = snprintf(buf, buf_len, "foo"); buf += ret; blen -= ret; } ... if (ret < 0) return ret; blen -= ret; return buf_len - blen; =============== into this: --------------- if (condition) arm_spe_pkt_snprintf(&err, &buf, &blen, "foo"); ... return err ?: (int)(buf_len - blen); --------------- And "diff" is getting really ahead of itself here and tries to be super clever, which leads to this hard to read patch. But I don't think there is anything we can really do here, this is already the minimal version. Leo adds the optimisations only later on, in other patches. Cheers, Andre > >> If the series is otherwise mature though, then this rework may be >> overkill. >> >>> --- >>> .../arm-spe-decoder/arm-spe-pkt-decoder.c | 267 ++++++++---------- >>> 1 file changed, 117 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..1ecaf9805b79 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 >>> #include >>> #include >>> +#include >>> >>> #include "arm-spe-pkt-decoder.h" >>> >>> @@ -258,192 +259,158 @@ 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; >>> + >>> + /* 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; >> >> What happens on buffer overrun (i.e., ret >= *blen)? >> >> It looks to me like we'll advance buf_p too far, blen will wrap around, >> and the string at *buf_p won't be null terminated. Because the return >> value is still >= 0, this condition will be returned up the stack as >> "success". > > Thanks for pointint out this. I never note for the potential issue > caused by returned value (ret >= *blen); checked again for the > manual, it says: > > "The functions snprintf() and vsnprintf() do not write more than size > bytes (including the terminating null byte ('\0')). If the output was > truncated due to this limit, then the return value is the number of > characters (excluding the terminating null byte) which would have > been written to the final string if enough space had been available. > Thus, a return value of size or more means that the output was > truncated." > >> Perhaps this can never happen given the actual buffer sizes and strings >> being printed, but it feels a bit unsafe. >> >> >> It may be better to clamp the adjustments to *buf_p and *blen to >> *blen - 1 in this case, and explicitly set (*buf_p)[*blen - 1] to '\0'. >> We _may_ want indicate failure in the return from arm_spe_pkt_desc() in >> this situation, but I don't know enough about how this code is called to >> enable me to judge that. > > The caller arm_spe_dump() will print out the string if the return > value > 0 [1]; so I think it can simply return the string length which > has been written to the buffer (with the clamped value). The function > can be refined as below: > > 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 - 1, fmt, ap); > va_end(ap); > > if (ret < 0) { > if (err && !*err) > *err = ret; > } else { > > /* > * A return value of (*blen - 1) or more means that the > * output was truncated and the buffer is overrun. > */ > if (ret >= (*blen - 1)) { > (*buf_p)[*blen - 1] = '\0'; > > /* > * Set *err to -1 to avoid overflow if tries to > * fill this buffer sequentially. > */ > if (err && !*err) > *err = -1; > > /* Clamp the size of characters printed */ > ret = min(ret, *blen); > } > > *buf_p += ret; > *blen -= ret; > } > > return ret; > } > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/util/arm-spe.c#n116 > >> (Note, this issue is not introduced by this patch, but this refactoring >> makes it easier to address it in a single place -- so it may now be >> worth doing so.) > > Agree. > >>> + } 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; >> >> It looks like we now fall off the bottom of the switch() here. It's >> preferable to add a break, both to document the intended code flow, and >> to avoid accidents if another case is added later. > > Will do this. > >>> - } >>> + return err ?: (int)(buf_len - blen); >> >> Nit: unexplained type cast. Does the result definitely fit into an int? >> If not, why doesn't it matter? > > The case is to dismiss the compiler warning. > > GCC doesn't compliant for the code: > > return buf_len - blen; > > But GCC compliants type mismatch after change to code: > > return err ?: buf_len - blen; > >> Also: >> >> If the actual return value is important for the caller to determine the >> number of bytes appended, then it would be better to compute it in one >> place. Otherwise, it would be better to squash all success returns to 0, >> rather than spend effort computing a value that may be misleading or >> wrong anyway. >> >> In its current form, it's tricky to see whether this patch derives the >> return value consistently for all cases. In particular, if some code >> patch does one or more arm_spe_pkt_snprintf(), followed by a >> return arm_spe_pkt_snprintf(); then the return value (which only takes >> the last arm_spe_pkt_desc() into account) would be wrong. It would be >> preferable if the return value for the success case were always >> computed from buf_len and blen, to avoid this risk. (I'm not saying >> this bug exists, just that it's hard to see from the patch that it >> doesn't exist.) > > I think I can go back to return value "buf_len - blen" and don't > check "err" anymore. > > If the string buffer is truncated due to size limitation, we can still > return "buf_len - blen" so can allow caller to dump string as > possible. > > If arm_spe_pkt_snprintf() returns -1 at the first call, "buf_len" is > equal to "blen", thus return value of "buf_len - blen" will be zero. > For this case, the caller will get to know there have no valid string > and will skip to print anything. > > Does this make sense? > >>> + >>> 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); >> >> Otherwise, the patch looks generally OK, but I'd like to see an answer >> on my points above. > > Thanks a lot for reviewing! > > Leo >