Hi Suzuki,
On 2024-12-05 at 22:31:51, Suzuki K Poulose (suzuki.poulose@xxxxxxx) wrote:
> 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@xxxxxxxxxxx>
> > Signed-off-by: Tanmay Jagdale <tanmay@xxxxxxxxxxx>
> > Signed-off-by: Linu Cherian <lcherian@xxxxxxxxxxx>
> > ---
> > .../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() ?
Ack. Will do that change.
>
>
> > + /* 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.
Will remove the invocation of this function during tmc_crashdata_read
and move it to tmc_probe .
+ if (is_tmc_crashdata_valid(drvdata) &&
+ !tmc_prepare_crashdata(drvdata))
+ register_crash_dev_interface(drvdata, desc.name);
return ret;
}
>
>
> > +
> > + if (status & 0x1)
>
> minor nit: s/0x1/TMC_STS_FULL ?
Ack.
>
> > + 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 ?
Thanks for pointing this out. Somehow missed this.
>
>
> > +
> > + drvdata->reading = true;
>
> Also, we agreed to not overload "drvdata->reading" ?
>
> See
> https://lkml.kernel.org/r/20241017114054.GC896339@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> 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 ?
Ack.
>
>
>
> 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)
> > {
>
>
