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Date: Mon, 29 Jan 2024 16:33:39 +0000
From: Frank Li <frank.li@....com>
To: Xu Yang <xu.yang_2@....com>, "will@...nel.org" <will@...nel.org>,
"mark.rutland@....com" <mark.rutland@....com>, "robh+dt@...nel.org"
<robh+dt@...nel.org>, "krzysztof.kozlowski+dt@...aro.org"
<krzysztof.kozlowski+dt@...aro.org>, "conor+dt@...nel.org"
<conor+dt@...nel.org>, "shawnguo@...nel.org" <shawnguo@...nel.org>,
"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "kernel@...gutronix.de"
<kernel@...gutronix.de>, "festevam@...il.com" <festevam@...il.com>,
"john.g.garry@...cle.com" <john.g.garry@...cle.com>, "jolsa@...nel.org"
<jolsa@...nel.org>, "namhyung@...nel.org" <namhyung@...nel.org>,
"irogers@...gle.com" <irogers@...gle.com>
CC: dl-linux-imx <linux-imx@....com>, "mike.leach@...aro.org"
<mike.leach@...aro.org>, "leo.yan@...aro.org" <leo.yan@...aro.org>,
"peterz@...radead.org" <peterz@...radead.org>, "mingo@...hat.com"
<mingo@...hat.com>, "acme@...nel.org" <acme@...nel.org>,
"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
"adrian.hunter@...el.com" <adrian.hunter@...el.com>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>, "devicetree@...r.kernel.org"
<devicetree@...r.kernel.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "linux-perf-users@...r.kernel.org"
<linux-perf-users@...r.kernel.org>
Subject: RE: [PATCH v3 3/4] perf: imx_perf: limit counter ID from user space
and optimize counter usage
> -----Original Message-----
> From: Xu Yang <xu.yang_2@....com>
> Sent: Monday, January 29, 2024 4:15 AM
> To: Frank Li <frank.li@....com>; will@...nel.org; mark.rutland@....com;
> robh+dt@...nel.org; krzysztof.kozlowski+dt@...aro.org;
> conor+dt@...nel.org; shawnguo@...nel.org; s.hauer@...gutronix.de;
> kernel@...gutronix.de; festevam@...il.com; john.g.garry@...cle.com;
> jolsa@...nel.org; namhyung@...nel.org; irogers@...gle.com
> Cc: dl-linux-imx <linux-imx@....com>; mike.leach@...aro.org;
> leo.yan@...aro.org; peterz@...radead.org; mingo@...hat.com;
> acme@...nel.org; alexander.shishkin@...ux.intel.com;
> adrian.hunter@...el.com; Xu Yang <xu.yang_2@....com>; linux-arm-
> kernel@...ts.infradead.org; devicetree@...r.kernel.org; linux-
> kernel@...r.kernel.org; linux-perf-users@...r.kernel.org
> Subject: [PATCH v3 3/4] perf: imx_perf: limit counter ID from user space and
> optimize counter usage
>
> The user can pass any counter ID to perf app. However, current pmu driver
> doesn't judge the validity of the counter ID. This will add necessary
> check for counter ID from user space. Besides, this pmu has 10 counters
> except cycle counter which can be used to count reference events and
> counter specific evnets. This will also add supports to auto allocate
> counter if the user doesn't pass it the perf. Then, the usage of counter
> will be optimized.
>
> Signed-off-by: Xu Yang <xu.yang_2@....com>
>
> ---
> Changes in v2:
> - limit counter ID from user to 0-10
> - combine dynamic and static allocation of counter
> Changes in v3:
> - no changes
> ---
> drivers/perf/fsl_imx9_ddr_perf.c | 69
> +++++++++++++++++++++++++++++++-
> 1 file changed, 67 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/perf/fsl_imx9_ddr_perf.c
> b/drivers/perf/fsl_imx9_ddr_perf.c
> index fd118773508d..4bb80050920c 100644
> --- a/drivers/perf/fsl_imx9_ddr_perf.c
> +++ b/drivers/perf/fsl_imx9_ddr_perf.c
> @@ -51,6 +51,7 @@
>
> #define NUM_COUNTERS 11
> #define CYCLES_COUNTER 0
> +#define CYCLES_EVENT_ID 0
>
> #define to_ddr_pmu(p) container_of(p, struct ddr_pmu, pmu)
>
> @@ -235,6 +236,14 @@ static struct attribute *ddr_perf_events_attrs[] = {
> NULL,
> };
>
> +static bool ddr_perf_is_specific_event(int event)
Why call specific? Name is too general. Such as is_fixed? Or Is_with_filter?
Need know what specific?
> +{
> + if (event >= 64 && event <= 73)
> + return true;
> + else
> + return false;
> +}
> +
> static const struct attribute_group ddr_perf_events_attr_group = {
> .name = "events",
> .attrs = ddr_perf_events_attrs,
> @@ -507,6 +516,7 @@ static int ddr_perf_event_init(struct perf_event
> *event)
> struct ddr_pmu *pmu = to_ddr_pmu(event->pmu);
> struct hw_perf_event *hwc = &event->hw;
> struct perf_event *sibling;
> + int event_id, counter;
>
> if (event->attr.type != event->pmu->type)
> return -ENOENT;
> @@ -519,6 +529,18 @@ static int ddr_perf_event_init(struct perf_event
> *event)
> return -EOPNOTSUPP;
> }
>
> + counter = (event->attr.config & 0xFF00) >> 8;
Define 0xFF00?
> + if (counter > NUM_COUNTERS) {
> + dev_warn(pmu->dev, "Only counter 0-10 is supported!\n");
> + return -EINVAL;
> + }
> +
> + event_id = event->attr.config & 0x00FF;
same for hardcode 0x00FF
> + if (ddr_perf_is_specific_event(event_id) && counter == 0) {
> + dev_err(pmu->dev, "Need specify counter for counter
> specific events!\n");
> + return -EINVAL;
> + }
> +
> /*
> * We must NOT create groups containing mixed PMUs, although
> software
> * events are acceptable (for example to create a CCN group
> @@ -552,6 +574,39 @@ static void ddr_perf_event_start(struct perf_event
> *event, int flags)
> hwc->state = 0;
> }
>
> +static int ddr_perf_alloc_counter(struct ddr_pmu *pmu, int event, int
> counter)
> +{
> + int i;
> +
> + if (event == CYCLES_EVENT_ID) {
> + /*
> + * Always map cycle event to counter 0.
> + * Cycles counter is dedicated for cycle event
> + * can't used for the other events.
> + */
> + if (pmu->events[CYCLES_COUNTER] == NULL)
> + return CYCLES_COUNTER;
> + } else if (counter != 0) {
> + /*
> + * 1. ddr_perf_event_init() will make sure counter
> + * is not 0 for counter specific events.
> + * 2. Allow specify counter for referene event too.
> + */
> + if (pmu->events[counter] == NULL)
> + return counter;
> + } else {
> + /*
> + * Counter may be 0 if user doesn't specify it.
> + * Auto allocate counter for referene event.
> + */
> + for (i = 1; i < NUM_COUNTERS; i++)
> + if (pmu->events[i] == NULL)
> + return i;
> + }
> +
> + return -ENOENT;
> +}
> +
> static int ddr_perf_event_add(struct perf_event *event, int flags)
> {
> struct ddr_pmu *pmu = to_ddr_pmu(event->pmu);
> @@ -559,9 +614,17 @@ static int ddr_perf_event_add(struct perf_event
> *event, int flags)
> int cfg = event->attr.config;
> int cfg1 = event->attr.config1;
> int cfg2 = event->attr.config2;
> - int counter;
> + int event_id, counter;
>
> - counter = (cfg & 0x0000FF00) >> 8;
> + event_id = cfg & 0x00FF;
> + counter = (cfg & 0xFF00) >> 8;
> +
> + /* check if counter is available */
> + counter = ddr_perf_alloc_counter(pmu, event_id, counter);
> + if (counter < 0) {
> + dev_dbg(pmu->dev, "There are not enough counters\n");
> + return -EOPNOTSUPP;
> + }
>
> pmu->events[counter] = event;
> pmu->active_events++;
> @@ -597,9 +660,11 @@ static void ddr_perf_event_del(struct perf_event
> *event, int flags)
> {
> struct ddr_pmu *pmu = to_ddr_pmu(event->pmu);
> struct hw_perf_event *hwc = &event->hw;
> + int counter = hwc->idx;
>
> ddr_perf_event_stop(event, PERF_EF_UPDATE);
>
> + pmu->events[counter] = NULL;
> pmu->active_events--;
> hwc->idx = -1;
> }
> --
> 2.34.1
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