[PATCH v12 5/8] coresight: tmc: Add support for reading crash data
Suzuki K Poulose
suzuki.poulose at arm.com
Thu Dec 5 09:01:51 PST 2024
Hi Linu,
On 29/11/2024 08:47, Linu Cherian wrote:
> * Add support for reading crashdata using special device files.
> The special device files /dev/crash_tmc_xxx would be available
> for read file operation only when the crash data is valid.
>
> * User can read the crash data as below
>
> For example, for reading crash data from tmc_etf sink
>
> #dd if=/dev/crash_tmc_etfXX of=~/cstrace.bin
>
Unfortunately there is still a bug that I picked up, see below for the
barrier_packet insertion.
> Signed-off-by: Anil Kumar Reddy <areddy3 at marvell.com>
> Signed-off-by: Tanmay Jagdale <tanmay at marvell.com>
> Signed-off-by: Linu Cherian <lcherian at marvell.com>
> ---
> .../hwtracing/coresight/coresight-tmc-core.c | 231 +++++++++++++++++-
> .../hwtracing/coresight/coresight-tmc-etr.c | 19 +-
> drivers/hwtracing/coresight/coresight-tmc.h | 13 +-
> 3 files changed, 260 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> index 1e3938ec12cb..5f3789314c4d 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> @@ -105,6 +105,151 @@ u32 tmc_get_memwidth_mask(struct tmc_drvdata *drvdata)
> return mask;
> }
>
> +bool is_tmc_crashdata_valid(struct tmc_drvdata *drvdata)
> +{
> + struct tmc_crash_metadata *mdata;
> +
> + if (!tmc_has_reserved_buffer(drvdata) ||
> + !tmc_has_crash_mdata_buffer(drvdata))
> + return false;
> +
> + mdata = drvdata->crash_mdata.vaddr;
> +
> + /* Check version match */
> + if (mdata->version != CS_CRASHDATA_VERSION)
> + return false;
> +
> + /* Check for valid metadata */
> + if (!mdata->valid) {
> + dev_dbg(&drvdata->csdev->dev,
> + "Data invalid in tmc crash metadata\n");
> + return false;
> + }
> +
> + /*
> + * Buffer address given by metadata for retrieval of trace data
> + * from previous boot is expected to be same as the reserved
> + * trace buffer memory region provided through DTS
> + */
> + if (drvdata->resrv_buf.paddr != mdata->trace_paddr) {
> + dev_dbg(&drvdata->csdev->dev,
> + "Trace buffer address of previous boot invalid\n");
> + return false;
> + }
> +
> + /* Check data integrity of metadata */
> + if (mdata->crc32_mdata != find_crash_metadata_crc(mdata)) {
> + dev_dbg(&drvdata->csdev->dev,
> + "CRC mismatch in tmc crash metadata\n");
> + return false;
> + }
> + /* Check data integrity of tracedata */
> + if (mdata->crc32_tdata != find_crash_tracedata_crc(drvdata, mdata)) {
> + dev_dbg(&drvdata->csdev->dev,
> + "CRC mismatch in tmc crash tracedata\n");
> + return false;
> + }
> +
> + return true;
> +}
> +
> +int tmc_read_prepare_crashdata(struct tmc_drvdata *drvdata)
> +{
> + int ret = 0;
> + u32 status, size;
> + u64 rrp, rwp, dba;
> + unsigned long flags;
> + struct tmc_resrv_buf *rbuf;
> + struct tmc_crash_metadata *mdata;
> +
> + spin_lock_irqsave(&drvdata->spinlock, flags);
> +
> + if (drvdata->reading) {
> + ret = -EBUSY;
> + goto out;
> + }
> +
> + if (!is_tmc_crashdata_valid(drvdata)) {
> + ret = -ENXIO;
> + goto out;
> + }
> +
> + mdata = drvdata->crash_mdata.vaddr;
> + rbuf = &drvdata->resrv_buf;
> +
> + rrp = mdata->tmc_rrp;
> + rwp = mdata->tmc_rwp;
> + dba = mdata->tmc_dba;
> + status = mdata->tmc_sts;
> + size = mdata->tmc_ram_size << 2;
> +
> + /* Sync the buffer pointers */
> + rbuf->offset = rrp - dba;
> + if (status & TMC_STS_FULL)
> + rbuf->len = size;
> + else
> + rbuf->len = rwp - rrp;
> +
I believe all of the above can be done one time probe and don't need to
be repeated every time we do a read_prepare() ?
> + /* Additional sanity checks for validating metadata */
> + if ((rbuf->offset > size) ||
> + (rbuf->len > size)) {
> + dev_dbg(&drvdata->csdev->dev,
> + "Offset and length invalid in tmc crash metadata\n");
> + return -EINVAL;
> + }
Ideally this should also be done once and "don't expose" crash_tmc
device if the above is invalid in metada.
> +
> + if (status & 0x1)
minor nit: s/0x1/TMC_STS_FULL ?
> + coresight_insert_barrier_packet(drvdata->buf);
And this looks completely out of nowhere and corrupting the drvdata->buf
? drvdata->buf is for active sessions, which we haven't set here ?
> +
> + drvdata->reading = true;
Also, we agreed to not overload "drvdata->reading" ?
See
https://lkml.kernel.org/r/20241017114054.GC896339@hyd1403.caveonetworks.com
We are allowed to the ETR (which drvdata->reading prevents from btw)
while crash data is being read. You could instead move it to
drvdata->resrv_buf->reading ?
Suzuki
> +out:
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return ret;
> +}
> +
> +int tmc_read_unprepare_crashdata(struct tmc_drvdata *drvdata)
> +{
> + unsigned long flags;
> + struct tmc_resrv_buf *rbuf;
> +
> + spin_lock_irqsave(&drvdata->spinlock, flags);
> +
> + rbuf = &drvdata->resrv_buf;
> + /* Reset valid length */
> + rbuf->len = 0;
> +
> + drvdata->reading = false;
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> +
> + return 0;
> +}
> +
> +static inline ssize_t tmc_get_resvbuf_trace(struct tmc_drvdata *drvdata,
> + loff_t pos, size_t len, char **bufpp)
> +{
> + s64 offset;
> + ssize_t actual = len;
> + struct tmc_resrv_buf *rbuf = &drvdata->resrv_buf;
> +
> + if (pos + actual > rbuf->len)
> + actual = rbuf->len - pos;
> + if (actual <= 0)
> + return 0;
> +
> + /* Compute the offset from which we read the data */
> + offset = rbuf->offset + pos;
> + if (offset >= rbuf->size)
> + offset -= rbuf->size;
> +
> + /* Adjust the length to limit this transaction to end of buffer */
> + actual = (actual < (rbuf->size - offset)) ?
> + actual : rbuf->size - offset;
> +
> + *bufpp = (char *)rbuf->vaddr + offset;
> +
> + return actual;
> +}
> +
> static int tmc_read_prepare(struct tmc_drvdata *drvdata)
> {
> int ret = 0;
> @@ -223,6 +368,69 @@ static const struct file_operations tmc_fops = {
> .release = tmc_release,
> };
>
> +static int tmc_crashdata_open(struct inode *inode, struct file *file)
> +{
> + int ret;
> + struct tmc_drvdata *drvdata = container_of(file->private_data,
> + struct tmc_drvdata,
> + crashdev);
> +
> + ret = tmc_read_prepare_crashdata(drvdata);
> + if (ret)
> + return ret;
> +
> + nonseekable_open(inode, file);
> +
> + dev_dbg(&drvdata->csdev->dev, "%s: successfully opened\n", __func__);
> + return 0;
> +}
> +
> +static ssize_t tmc_crashdata_read(struct file *file, char __user *data,
> + size_t len, loff_t *ppos)
> +{
> + char *bufp;
> + ssize_t actual;
> + struct tmc_drvdata *drvdata = container_of(file->private_data,
> + struct tmc_drvdata,
> + crashdev);
> +
> + actual = tmc_get_resvbuf_trace(drvdata, *ppos, len, &bufp);
> + if (actual <= 0)
> + return 0;
> +
> + if (copy_to_user(data, bufp, actual)) {
> + dev_dbg(&drvdata->csdev->dev,
> + "%s: copy_to_user failed\n", __func__);
> + return -EFAULT;
> + }
> +
> + *ppos += actual;
> + dev_dbg(&drvdata->csdev->dev, "%zu bytes copied\n", actual);
> +
> + return actual;
> +
> +}
> +
> +static int tmc_crashdata_release(struct inode *inode, struct file *file)
> +{
> + int ret = 0;
> + struct tmc_drvdata *drvdata = container_of(file->private_data,
> + struct tmc_drvdata,
> + crashdev);
> +
> + ret = tmc_read_unprepare_crashdata(drvdata);
> +
> + dev_dbg(&drvdata->csdev->dev, "%s: released\n", __func__);
> + return ret;
> +}
> +
> +static const struct file_operations tmc_crashdata_fops = {
> + .owner = THIS_MODULE,
> + .open = tmc_crashdata_open,
> + .read = tmc_crashdata_read,
> + .release = tmc_crashdata_release,
> +};
> +
> static enum tmc_mem_intf_width tmc_get_memwidth(u32 devid)
> {
> enum tmc_mem_intf_width memwidth;
> @@ -532,6 +740,20 @@ static u32 tmc_etr_get_max_burst_size(struct device *dev)
> return burst_size;
> }
>
> +static void register_crash_dev_interface(struct tmc_drvdata *drvdata,
> + const char *name)
> +{
> + drvdata->crashdev.name =
> + devm_kasprintf(&drvdata->csdev->dev, GFP_KERNEL, "%s_%s", "crash", name);
> + drvdata->crashdev.minor = MISC_DYNAMIC_MINOR;
> + drvdata->crashdev.fops = &tmc_crashdata_fops;
> + if (misc_register(&drvdata->crashdev)) {
> + dev_dbg(&drvdata->csdev->dev,
> + "Failed to setup user interface for crashdata\n");
> + drvdata->crashdev.fops = NULL;
> + }
> +}
> +
> static int __tmc_probe(struct device *dev, struct resource *res)
> {
> int ret = 0;
> @@ -632,8 +854,13 @@ static int __tmc_probe(struct device *dev, struct resource *res)
> drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
> drvdata->miscdev.fops = &tmc_fops;
> ret = misc_register(&drvdata->miscdev);
> - if (ret)
> + if (ret) {
> coresight_unregister(drvdata->csdev);
> + goto out;
> + }
> +
> + if (is_tmc_crashdata_valid(drvdata))
> + register_crash_dev_interface(drvdata, desc.name);
> out:
> return ret;
> }
> @@ -687,6 +914,8 @@ static void __tmc_remove(struct device *dev)
> * handler to this device is closed.
> */
> misc_deregister(&drvdata->miscdev);
> + if (drvdata->crashdev.fops)
> + misc_deregister(&drvdata->crashdev);
> coresight_unregister(drvdata->csdev);
> }
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index fb944a68a11c..18752f58dfa6 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -2012,6 +2012,23 @@ static ssize_t buf_mode_preferred_show(struct device *dev,
> return sysfs_emit(buf, "%s\n", buf_modes_str[drvdata->etr_mode]);
> }
>
> +static int buf_mode_set_resrv(struct tmc_drvdata *drvdata)
> +{
> + unsigned long flags;
> + int err = 0;
> +
> + /* Ensure there are no active crashdata read sessions */
> + spin_lock_irqsave(&drvdata->spinlock, flags);
> + if (!drvdata->reading) {
> + tmc_crashdata_set_invalid(drvdata);
> + drvdata->etr_mode = ETR_MODE_RESRV;
> +
> + } else
> + err = -1;
> + spin_unlock_irqrestore(&drvdata->spinlock, flags);
> + return err;
> +}
> +
> static ssize_t buf_mode_preferred_store(struct device *dev,
> struct device_attribute *attr,
> const char *buf, size_t size)
> @@ -2027,7 +2044,7 @@ static ssize_t buf_mode_preferred_store(struct device *dev,
> else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_CATU]) && buf_hw.has_catu)
> drvdata->etr_mode = ETR_MODE_CATU;
> else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_RESRV]) && buf_hw.has_resrv)
> - drvdata->etr_mode = ETR_MODE_RESRV;
> + return buf_mode_set_resrv(drvdata) ? -EBUSY : size;
> else if (sysfs_streq(buf, buf_modes_str[ETR_MODE_AUTO]))
> drvdata->etr_mode = ETR_MODE_AUTO;
> else
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index d76e83fc840b..2ece44e09911 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -195,11 +195,15 @@ struct etr_buf {
> * @paddr : Start address of reserved memory region.
> * @vaddr : Corresponding CPU virtual address.
> * @size : Size of reserved memory region.
> + * @offset : Offset of the trace data in the buffer for consumption.
> + * @len : Available trace data @buf (may round up to the beginning).
> */
> struct tmc_resrv_buf {
> phys_addr_t paddr;
> void *vaddr;
> size_t size;
> + unsigned long offset;
> + s64 len;
> };
>
> /**
> @@ -208,6 +212,8 @@ struct tmc_resrv_buf {
> * @base: memory mapped base address for this component.
> * @csdev: component vitals needed by the framework.
> * @miscdev: specifics to handle "/dev/xyz.tmc" entry.
> + * @crashdev: specifics to handle "/dev/crash_tmc_xyz" entry for reading
> + * crash tracedata.
> * @spinlock: only one at a time pls.
> * @pid: Process ID of the process that owns the session that is using
> * this component. For example this would be the pid of the Perf
> @@ -227,7 +233,7 @@ struct tmc_resrv_buf {
> * @idr_mutex: Access serialisation for idr.
> * @sysfs_buf: SYSFS buffer for ETR.
> * @perf_buf: PERF buffer for ETR.
> - * @resrv_buf: Used by ETR as hardware trace buffer and for trace data
> + * @resrv_buf: Used by ETR as hardware trace buffer and for trace data
> * retention (after crash) only when ETR_MODE_RESRV buffer
> * mode is enabled. Used by ETF for trace data retention
> * (after crash) by default.
> @@ -239,6 +245,7 @@ struct tmc_drvdata {
> void __iomem *base;
> struct coresight_device *csdev;
> struct miscdevice miscdev;
> + struct miscdevice crashdev;
> spinlock_t spinlock;
> pid_t pid;
> bool reading;
> @@ -309,6 +316,8 @@ void tmc_flush_and_stop(struct tmc_drvdata *drvdata);
> void tmc_enable_hw(struct tmc_drvdata *drvdata);
> void tmc_disable_hw(struct tmc_drvdata *drvdata);
> u32 tmc_get_memwidth_mask(struct tmc_drvdata *drvdata);
> +int tmc_read_prepare_crashdata(struct tmc_drvdata *drvdata);
> +int tmc_read_unprepare_crashdata(struct tmc_drvdata *drvdata);
>
> /* ETB/ETF functions */
> int tmc_read_prepare_etb(struct tmc_drvdata *drvdata);
> @@ -371,6 +380,8 @@ void tmc_sg_table_sync_data_range(struct tmc_sg_table *table,
> u64 offset, u64 size);
> ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table,
> u64 offset, size_t len, char **bufpp);
> +
> +bool is_tmc_crashdata_valid(struct tmc_drvdata *drvdata);
> static inline unsigned long
> tmc_sg_table_buf_size(struct tmc_sg_table *sg_table)
> {
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