| Message ID | 20190325215632.17013-4-mathieu.poirier@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | coresight: Add support for CPU-wide trace scenarios | expand |
On 03/25/2019 09:56 PM, Mathieu Poirier wrote: > Configure timestamps to be emitted at regular intervals in the trace > stream to temporally correlate instructions executed on different CPUs. > > Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> > --- > drivers/hwtracing/coresight/coresight-etm4x.c | 115 +++++++++++++++++- > 1 file changed, 112 insertions(+), 3 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c > index 732ae12fca9b..45c341a5aa0b 100644 > --- a/drivers/hwtracing/coresight/coresight-etm4x.c > +++ b/drivers/hwtracing/coresight/coresight-etm4x.c > @@ -138,8 +138,11 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) > drvdata->base + TRCCNTVRn(i)); > } > > - /* Resource selector pair 0 is always implemented and reserved */ > - for (i = 0; i < drvdata->nr_resource * 2; i++) > + /* > + * Resource selector pair 0 is always implemented and reserved. As > + * such start at 2. > + */ > + for (i = 2; i < drvdata->nr_resource * 2; i++) > writel_relaxed(config->res_ctrl[i], > drvdata->base + TRCRSCTLRn(i)); To be frank, that looks like a separate fix for the existing driver, from this series. > > @@ -201,6 +204,97 @@ static void etm4_enable_hw_smp_call(void *info) > arg->rc = etm4_enable_hw(arg->drvdata); > } > > +/* > + * The goal of function etm4_config_timestamp_event() is to configure a > + * counter that will tell the tracer to emit a timestamp packet when it > + * reaches zero. This is done in order to get a more fine grained idea > + * of when instructions are executed so that they can be correlated > + * with execution on other CPUs. > + * > + * To do this the counter itself is configured to self reload and > + * TRCRSCTLR1 (always true) used to get the counter to decrement. From > + * there a resource selector is configured with the counter and the > + * timestamp control register to use the resource selector to trigger the > + * event that will insert a timestamp packet in the stream. > + */ > +static int etm4_config_timestamp_event(struct etmv4_drvdata *drvdata) > +{ > + int i, ctridx, ret = -EINVAL; > + int counter, rselector; > + u32 val = 0; > + struct etmv4_config *config = &drvdata->config; > + > + /* No point in trying if we don't have at least one counter */ > + if (!drvdata->nr_cntr) > + goto out; > + > + /* Find a counter that hasn't been initialised */ > + for (i = 0; i < drvdata->nr_cntr; i++) > + if (config->cntr_val[i] == 0) > + break; > + > + /* Remember what counter we used */ > + counter = 1 << i; > + ctridx = i; > + > + /* All the counters have been configured already, bail out */ > + if (i == drvdata->nr_cntr) { > + pr_err("%s: no available counter found\n", __func__); > + goto out; > + } Should this be pr_debug ? This could be easily triggered to flood the dmesg. Also, I think the return code could be -ENODEV or -ENOSPC rather than -EINVAL in this case. > + > + /* > + * Initialise original and reload counter value to the smallest > + * possible value in order to get as much precision as we can. > + */ > + config->cntr_val[ctridx] = 1; > + config->cntrldvr[ctridx] = 1; We could delay the initialisation until we find the resource selector to avoid clearing them later. > + > + /* Set the trace counter control register */ > + val = 0x1 << 16 | /* Bit 16, reload counter automatically */ > + 0x0 << 7 | /* Select single resource selector */ > + 0x1; /* Resource selector 1, i.e always true */ > + > + config->cntr_ctrl[ctridx] = val; > + > + /* > + * Searching for an available resource selector to use, starting at > + * '2' since every implementation has at least 2 resource selector. > + * ETMIDR4 gives the number of resource selector _pairs_, > + * hence multiply by 2. > + */ > + for (i = 2; i < drvdata->nr_resource * 2; i++) > + if (!config->res_ctrl[i]) > + break; > + > + /* Remember what resource selector we used */ > + rselector = i; > + > + if (i == drvdata->nr_resource * 2) { > + pr_err("%s: no available resource selector found\n", __func__); > + Same as above. This shouldn't be an error, may be a debug. It is a crunch of resources, a usage error from the user and not kernel. > + /* Backout what we did and exit */ > + config->cntr_ctrl[ctridx] = 0; > + config->cntrldvr[ctridx] = 0; > + config->cntr_val[ctridx] = 0; > + goto out; > + } > + > + val = 0x2 << 16 | /* Group 0b0010 - Counter and sequencers */ > + counter << 0; /* Counter to use */ > + > + config->res_ctrl[i] = val; > + > + val = 0x0 << 7 | /* Select single resource selector */ > + rselector; /* Resource selector */ > + > + config->ts_ctrl = val; > + > + ret = 0; > +out: > + return ret; > +} > + > static int etm4_parse_event_config(struct etmv4_drvdata *drvdata, > struct perf_event *event) > { > @@ -236,9 +330,24 @@ static int etm4_parse_event_config(struct etmv4_drvdata *drvdata, > /* TRM: Must program this for cycacc to work */ > config->ccctlr = ETM_CYC_THRESHOLD_DEFAULT; > } > - if (attr->config & BIT(ETM_OPT_TS)) > + if (attr->config & BIT(ETM_OPT_TS)) { > + /* > + * Configure timestamps to be emitted at regular intervals in > + * order to correlate instructions executed on different CPUs > + * (CPU-wide trace scenarios). > + */ > + ret = etm4_config_timestamp_event(drvdata); > + > + /* > + * No need to go further if timestamp intervals can't > + * be configured. > + */ > + if (ret) > + goto out; > + > /* bit[11], Global timestamp tracing bit */ > config->cfg |= BIT(11); > + } > > if (attr->config & BIT(ETM_OPT_CTXTID)) > /* bit[6], Context ID tracing bit */ > Rest all looks good to me. Suzuki
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c index 732ae12fca9b..45c341a5aa0b 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.c +++ b/drivers/hwtracing/coresight/coresight-etm4x.c @@ -138,8 +138,11 @@ static int etm4_enable_hw(struct etmv4_drvdata *drvdata) drvdata->base + TRCCNTVRn(i)); } - /* Resource selector pair 0 is always implemented and reserved */ - for (i = 0; i < drvdata->nr_resource * 2; i++) + /* + * Resource selector pair 0 is always implemented and reserved. As + * such start at 2. + */ + for (i = 2; i < drvdata->nr_resource * 2; i++) writel_relaxed(config->res_ctrl[i], drvdata->base + TRCRSCTLRn(i)); @@ -201,6 +204,97 @@ static void etm4_enable_hw_smp_call(void *info) arg->rc = etm4_enable_hw(arg->drvdata); } +/* + * The goal of function etm4_config_timestamp_event() is to configure a + * counter that will tell the tracer to emit a timestamp packet when it + * reaches zero. This is done in order to get a more fine grained idea + * of when instructions are executed so that they can be correlated + * with execution on other CPUs. + * + * To do this the counter itself is configured to self reload and + * TRCRSCTLR1 (always true) used to get the counter to decrement. From + * there a resource selector is configured with the counter and the + * timestamp control register to use the resource selector to trigger the + * event that will insert a timestamp packet in the stream. + */ +static int etm4_config_timestamp_event(struct etmv4_drvdata *drvdata) +{ + int i, ctridx, ret = -EINVAL; + int counter, rselector; + u32 val = 0; + struct etmv4_config *config = &drvdata->config; + + /* No point in trying if we don't have at least one counter */ + if (!drvdata->nr_cntr) + goto out; + + /* Find a counter that hasn't been initialised */ + for (i = 0; i < drvdata->nr_cntr; i++) + if (config->cntr_val[i] == 0) + break; + + /* Remember what counter we used */ + counter = 1 << i; + ctridx = i; + + /* All the counters have been configured already, bail out */ + if (i == drvdata->nr_cntr) { + pr_err("%s: no available counter found\n", __func__); + goto out; + } + + /* + * Initialise original and reload counter value to the smallest + * possible value in order to get as much precision as we can. + */ + config->cntr_val[ctridx] = 1; + config->cntrldvr[ctridx] = 1; + + /* Set the trace counter control register */ + val = 0x1 << 16 | /* Bit 16, reload counter automatically */ + 0x0 << 7 | /* Select single resource selector */ + 0x1; /* Resource selector 1, i.e always true */ + + config->cntr_ctrl[ctridx] = val; + + /* + * Searching for an available resource selector to use, starting at + * '2' since every implementation has at least 2 resource selector. + * ETMIDR4 gives the number of resource selector _pairs_, + * hence multiply by 2. + */ + for (i = 2; i < drvdata->nr_resource * 2; i++) + if (!config->res_ctrl[i]) + break; + + /* Remember what resource selector we used */ + rselector = i; + + if (i == drvdata->nr_resource * 2) { + pr_err("%s: no available resource selector found\n", __func__); + + /* Backout what we did and exit */ + config->cntr_ctrl[ctridx] = 0; + config->cntrldvr[ctridx] = 0; + config->cntr_val[ctridx] = 0; + goto out; + } + + val = 0x2 << 16 | /* Group 0b0010 - Counter and sequencers */ + counter << 0; /* Counter to use */ + + config->res_ctrl[i] = val; + + val = 0x0 << 7 | /* Select single resource selector */ + rselector; /* Resource selector */ + + config->ts_ctrl = val; + + ret = 0; +out: + return ret; +} + static int etm4_parse_event_config(struct etmv4_drvdata *drvdata, struct perf_event *event) { @@ -236,9 +330,24 @@ static int etm4_parse_event_config(struct etmv4_drvdata *drvdata, /* TRM: Must program this for cycacc to work */ config->ccctlr = ETM_CYC_THRESHOLD_DEFAULT; } - if (attr->config & BIT(ETM_OPT_TS)) + if (attr->config & BIT(ETM_OPT_TS)) { + /* + * Configure timestamps to be emitted at regular intervals in + * order to correlate instructions executed on different CPUs + * (CPU-wide trace scenarios). + */ + ret = etm4_config_timestamp_event(drvdata); + + /* + * No need to go further if timestamp intervals can't + * be configured. + */ + if (ret) + goto out; + /* bit[11], Global timestamp tracing bit */ config->cfg |= BIT(11); + } if (attr->config & BIT(ETM_OPT_CTXTID)) /* bit[6], Context ID tracing bit */
Configure timestamps to be emitted at regular intervals in the trace stream to temporally correlate instructions executed on different CPUs. Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> --- drivers/hwtracing/coresight/coresight-etm4x.c | 115 +++++++++++++++++- 1 file changed, 112 insertions(+), 3 deletions(-)