Messages in this thread Patch in this message | | | Date | Tue, 3 Nov 2020 10:39:36 +0800 | From | Leo Yan <> | Subject | Re: [PATCH v6 06/21] perf arm-spe: Refactor printing string to buffer |
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On Mon, Nov 02, 2020 at 03:50:01PM +0000, André Przywara wrote: > On 30/10/2020 02:57, 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 <Dave.Martin@arm.com> > > Signed-off-by: Leo Yan <leo.yan@linaro.org> > > Wow, that's a bit tricky to review in its current incarnation, but it > looks alright to me.
Yes, I had the same feeling when I saw the generated patch :)
> I have some optimisation idea below, but that's a nit and the patch as > is seems correct to me (checked twice, the second time in an editor, > matching the lines), so: > > Reviewed-by: Andre Przywara <andre.przywara@arm.com> > > > ... > > > --- > > .../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 <endian.h> > > #include <byteswap.h> > > #include <linux/bitops.h> > > +#include <stdarg.h> > > > > #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; > > + } 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); > > Nothing critical, but in case you need to respin this series for > whatever reason, you might want to use NULL for the first argument, > since you return here and there is little point in setting err. Same for > other cases where you return directly from an arm_spe_pkt_snprintf() call. > But it doesn't hurt, so you could leave it as well, and it's more robust > in case someone extends the code later.
Makes sense for me. Eventually, we also can remove the local variable "err", so will do it. Thanks a lot!
> > + 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"); > > same here (and below, you get the idea ...) > > Cheers, > Andre > > > > + 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); > > } > > >
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