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() ?
+ /* 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@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 ?
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)
{
