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Message-ID: <20180109202128.GB21932@xps15>
Date: Tue, 9 Jan 2018 13:21:28 -0700
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Leo Yan <leo.yan@...aro.org>
Cc: Jonathan Corbet <corbet@....net>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Will Deacon <will.deacon@....com>, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
coresight@...ts.linaro.org
Subject: Re: [PATCH v3 6/6] coresight: etm4x: Support panic kdump
On Thu, Dec 21, 2017 at 04:20:15PM +0800, Leo Yan wrote:
> ETMv4 hardware information and configuration needs to be saved as
> metadata; these metadata should be compatible with tool 'perf' and
> can be used for tracing data analysis. ETMv4 usually works as tracer
> per CPU, we cannot wait to gather ETM info after the CPU has been panic
> and cannot execute dump operations for itself; so should gather
> metadata when the corresponding CPU is alive.
>
> Since values in TRCIDR{0, 1, 2, 8} and TRCAUTHSTATUS are read-only and
> won't change at the runtime. Those registers value are filled when
> tracers are instantiated.
>
> The configuration and control registers TRCCONFIGR and TRCTRACEIDR are
> dynamically configured, we record their value when enabling coresight
> path. When operating from sysFS tracer these two registers are recorded
> in etm4_enable_sysfs() and add kdump node into list, and remove the
> kdump node in etm4_disable_sysfs(). When operating from perf,
> etm_setup_aux() adds all tracers to the dump list and etm4_enable_perf()
> is used to record configuration registers and update dump buffer info,
> this can avoid unnecessary list addition and deletion operations.
> Removal of the tracers from the dump list is done in function
> free_event_data().
>
> Suggested-by: Mathieu Poirier <mathieu.poirier@...aro.org>
> Signed-off-by: Leo Yan <leo.yan@...aro.org>
> ---
> drivers/hwtracing/coresight/coresight-etm-perf.c | 12 +++++++++++-
> drivers/hwtracing/coresight/coresight-etm4x.c | 23 +++++++++++++++++++++++
> drivers/hwtracing/coresight/coresight-etm4x.h | 15 +++++++++++++++
> 3 files changed, 49 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-etm-perf.c b/drivers/hwtracing/coresight/coresight-etm-perf.c
> index 8a0ad77..fec779b 100644
> --- a/drivers/hwtracing/coresight/coresight-etm-perf.c
> +++ b/drivers/hwtracing/coresight/coresight-etm-perf.c
> @@ -137,6 +137,12 @@ static void free_event_data(struct work_struct *work)
> }
>
> for_each_cpu(cpu, mask) {
> + struct coresight_device *csdev;
> +
> + csdev = per_cpu(csdev_src, cpu);
> + if (csdev)
> + coresight_kdump_del(csdev);
> +
> if (!(IS_ERR_OR_NULL(event_data->path[cpu])))
> coresight_release_path(event_data->path[cpu]);
> }
> @@ -195,7 +201,7 @@ static void etm_free_aux(void *data)
> static void *etm_setup_aux(int event_cpu, void **pages,
> int nr_pages, bool overwrite)
> {
> - int cpu;
> + int cpu, ret;
> cpumask_t *mask;
> struct coresight_device *sink;
> struct etm_event_data *event_data = NULL;
> @@ -238,6 +244,10 @@ static void *etm_setup_aux(int event_cpu, void **pages,
> event_data->path[cpu] = coresight_build_path(csdev, sink);
> if (IS_ERR(event_data->path[cpu]))
> goto err;
> +
> + ret = coresight_kdump_add(csdev, cpu);
Aren't you missing the configuration for trcconfigr and trctraceidr?
> + if (ret)
> + goto err;
> }
>
> if (!sink_ops(sink)->alloc_buffer)
> diff --git a/drivers/hwtracing/coresight/coresight-etm4x.c b/drivers/hwtracing/coresight/coresight-etm4x.c
> index cf364a5..cbde398 100644
> --- a/drivers/hwtracing/coresight/coresight-etm4x.c
> +++ b/drivers/hwtracing/coresight/coresight-etm4x.c
> @@ -258,10 +258,19 @@ static int etm4_enable_perf(struct coresight_device *csdev,
> static int etm4_enable_sysfs(struct coresight_device *csdev)
> {
> struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
> + struct etmv4_config *config = &drvdata->config;
> + struct etmv4_metadata *metadata = &drvdata->metadata;
> int ret;
>
> spin_lock(&drvdata->spinlock);
>
> + /* Update meta data and add into kdump list */
> + metadata->trcconfigr = config->cfg;
> + metadata->trctraceidr = drvdata->trcid;
> +
> + coresight_kdump_add(csdev, drvdata->cpu);
> + coresight_kdump_update(csdev, (char *)metadata, sizeof(*metadata));
> +
> /*
> * Executing etm4_enable_hw on the cpu whose ETM is being enabled
> * ensures that register writes occur when cpu is powered.
> @@ -384,6 +393,9 @@ static void etm4_disable_sysfs(struct coresight_device *csdev)
> */
> smp_call_function_single(drvdata->cpu, etm4_disable_hw, drvdata, 1);
>
> + /* Delete from kdump list */
> + coresight_kdump_del(csdev);
> +
> spin_unlock(&drvdata->spinlock);
> cpus_read_unlock();
>
> @@ -438,6 +450,7 @@ 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 +603,16 @@ 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);
> }
>
> 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
This is a duplicate of the magic value found in cs-etm.h but I'm not sure of
what we'll do about that. It is probably time to come up
with a shared file between the kernel and the perf tools, just like
coresight-pmu.h. You can have a stab at it or concentrate on my previous
comments for now - it's entirely up to you.
> +
> +struct etmv4_metadata {
> + u64 magic;
> + u64 cpu;
> + u64 trcconfigr;
> + u64 trctraceidr;
> + u64 trcidr0;
> + u64 trcidr1;
> + u64 trcidr2;
> + u64 trcidr8;
> + u64 trcauthstatus;
> +};
Same here... This is a duplicate of struct etmv4_drvdata. Again not sure about
the best way to handle this. I'll think about it.
> +
> /**
> * 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;
> };
>
> /* Address comparator access types */
> --
> 2.7.4
>
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