Re: [PATCH v4 6/6] coresight: etm4x: Support panic kdump

On Fri, Mar 30, 2018 at 11:15:24AM +0800, Leo Yan wrote:

ETMv4 hardware information and configuration needs to be saved as metadata; the metadata format should be compatible with 'perf' tool and finally is used by tracing data decoder. ETMv4 works as tracer per CPU, we cannot wait for gathering ETM info after CPU panic has happened in case there have CPU is locked up and can't response inter-processor interrupt for execution dump operations; so it's more reliable to gather tracer metadata when all of the CPUs are alive.

This patch saves ETMv4 metadata but with the different method for different registers. Since values in TRCIDR{0, 1, 2, 8} and TRCAUTHSTATUS are read-only and won't change afterward, thus those registers values are filled into metadata structure when tracers are instantiated. The configuration and control registers TRCCONFIGR and TRCTRACEIDR are dynamically configured, their values are recorded during tracer enabling phase.

To avoid unnecessary overload introduced by set/clear operations for updating kdump node, we only set ETMv4 metadata info for the corresponding kdump node at initialization and won't be cleared anymore.

Suggested-by: Mathieu Poirier mathieu.poirier@linaro.org Signed-off-by: Leo Yan leo.yan@linaro.org

---

drivers/hwtracing/coresight/coresight-etm4x.c | 27 +++++++++++++++++++++++++++ drivers/hwtracing/coresight/coresight-etm4x.h | 15 +++++++++++++++ 2 files changed, 42 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c index cf364a5..88b1e19 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.c +++ b/drivers/hwtracing/coresight/coresight-etm4x.c @@ -288,6 +288,8 @@ static int etm4_enable(struct coresight_device *csdev, int ret; u32 val; struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

• struct etmv4_config *config = &drvdata->config;
• struct etmv4_metadata *metadata = &drvdata->metadata;

val = local_cmpxchg(&drvdata->mode, CS_MODE_DISABLED, mode); @@ -306,6 +308,10 @@ static int etm4_enable(struct coresight_device *csdev, ret = -EINVAL; }

• /* Update tracer meta data after tracer configuration */
• metadata->trcconfigr = config->cfg;
• metadata->trctraceidr = drvdata->trcid;
• /* The tracer didn't start */ if (ret) local_set(&drvdata->mode, CS_MODE_DISABLED);

@@ -438,6 +444,7 @@ static void etm4_init_arch_data(void *info) u32 etmidr4; u32 etmidr5; struct etmv4_drvdata *drvdata = info;

• struct etmv4_metadata *metadata = &drvdata->metadata;

/* Make sure all registers are accessible */ etm4_os_unlock(drvdata); @@ -590,6 +597,16 @@ static void etm4_init_arch_data(void *info) drvdata->nrseqstate = BMVAL(etmidr5, 25, 27); /* NUMCNTR, bits[30:28] number of counters available for tracing */ drvdata->nr_cntr = BMVAL(etmidr5, 28, 30);

• /* Update metadata */
• metadata->magic = ETM4_METADATA_MAGIC;
• metadata->cpu = drvdata->cpu;
• metadata->trcidr0 = readl_relaxed(drvdata->base + TRCIDR0);
• metadata->trcidr1 = readl_relaxed(drvdata->base + TRCIDR1);
• metadata->trcidr2 = readl_relaxed(drvdata->base + TRCIDR2);
• metadata->trcidr8 = readl_relaxed(drvdata->base + TRCIDR8);
• metadata->trcauthstatus = readl_relaxed(drvdata->base + TRCAUTHSTATUS);
• CS_LOCK(drvdata->base);

} @@ -957,6 +974,7 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id) struct device *dev = &adev->dev; struct coresight_platform_data *pdata = NULL; struct etmv4_drvdata *drvdata;

• struct etmv4_metadata *metadata; struct resource *res = &adev->res; struct coresight_desc desc = { 0 }; struct device_node *np = adev->dev.of_node;

@@ -1027,6 +1045,15 @@ static int etm4_probe(struct amba_device *adev, const struct amba_id *id) goto err_arch_supported; }

• /* Set source device handler and metadata into kdump node */
• metadata = &drvdata->metadata;
• ret = coresight_kdump_source(drvdata->cpu, drvdata->csdev,

• 		     (char *)metadata, sizeof(*metadata));
  

• if (ret) {

• coresight_unregister(drvdata->csdev);
  

• goto err_arch_supported;
  

• }
• ret = etm_perf_symlink(drvdata->csdev, true); if (ret) { coresight_unregister(drvdata->csdev);

diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h index b3b5ea7..08dc8b7 100644 --- a/drivers/hwtracing/coresight/coresight-etm4x.h +++ b/drivers/hwtracing/coresight/coresight-etm4x.h @@ -198,6 +198,20 @@ #define ETM_EXLEVEL_NS_HYP BIT(14) #define ETM_EXLEVEL_NS_NA BIT(15) +#define ETM4_METADATA_MAGIC 0x4040404040404040ULL

Please dd a comment that this needs to be kept in sync with __perf_cs_etmv4_magic in tools/perf/util/cs-etm.h.

+struct etmv4_metadata {

• u64 magic;
• u64 cpu;
• u64 trcconfigr;
• u64 trctraceidr;
• u64 trcidr0;
• u64 trcidr1;
• u64 trcidr2;
• u64 trcidr8;
• u64 trcauthstatus;

+};

/**

• struct etmv4_config - configuration information related to an ETMv4
• @mode: Controls various modes supported by this ETM.

@@ -393,6 +407,7 @@ struct etmv4_drvdata { bool atbtrig; bool lpoverride; struct etmv4_config config;

• struct etmv4_metadata metadata;

Structure documentation please.

}; /* Address comparator access types */ -- 2.7.4