Re: [PATCH 3/4] remoteproc: add support for a new 64-bit trace version

From: Suman Anna
Date: Thu May 21 2020 - 15:42:26 EST

Hi Bjorn,

On 5/21/20 1:04 PM, Bjorn Andersson wrote:
On Wed 25 Mar 13:47 PDT 2020, Suman Anna wrote:

Introduce a new trace entry resource structure that accommodates
a 64-bit device address to support 64-bit processors. This is to
be used using an overloaded version value of 1 in the upper 32-bits
of the previous resource type field. The new resource still uses
32-bits for the length field (followed by a 32-bit reserved field,
so can be updated in the future), which is a sufficiently large
trace buffer size. A 32-bit padding field also had to be added
to align the device address on a 64-bit boundary, and match the
usage on the firmware side.

The remoteproc debugfs logic also has been adjusted accordingly.

Signed-off-by: Suman Anna <s-anna@xxxxxx>
---
drivers/remoteproc/remoteproc_core.c | 40 ++++++++++++++++++++-----
drivers/remoteproc/remoteproc_debugfs.c | 37 ++++++++++++++++++-----
include/linux/remoteproc.h | 26 ++++++++++++++++
3 files changed, 87 insertions(+), 16 deletions(-)

diff --git a/drivers/remoteproc/remoteproc_core.c b/drivers/remoteproc/remoteproc_core.c
index 53bc37c508c6..b9a097990862 100644
--- a/drivers/remoteproc/remoteproc_core.c
+++ b/drivers/remoteproc/remoteproc_core.c
@@ -609,21 +609,45 @@ void rproc_vdev_release(struct kref *ref)
*
* Returns 0 on success, or an appropriate error code otherwise
*/
-static int rproc_handle_trace(struct rproc *rproc, struct fw_rsc_trace *rsc,
+static int rproc_handle_trace(struct rproc *rproc, void *rsc,
int offset, int avail, u16 ver)
{
struct rproc_debug_trace *trace;
struct device *dev = &rproc->dev;
+ struct fw_rsc_trace *rsc1;
+ struct fw_rsc_trace2 *rsc2;
char name[15];
+ size_t rsc_size;
+ u32 reserved;
+ u64 da;
+ u32 len;
+
+ if (!ver) {

This looks like a switch to me, but I also do think this looks rather
crude, if you spin off the tail of this function and call it from a
rproc_handle_trace() and rproc_handle_trace64() I believe this would be
cleaner.

Yeah, ok. Will refactor for this in v2.


+ rsc1 = (struct fw_rsc_trace *)rsc;
+ rsc_size = sizeof(*rsc1);
+ reserved = rsc1->reserved;
+ da = rsc1->da;
+ len = rsc1->len;
+ } else if (ver == 1) {
+ rsc2 = (struct fw_rsc_trace2 *)rsc;
+ rsc_size = sizeof(*rsc2);
+ reserved = rsc2->reserved;
+ da = rsc2->da;
+ len = rsc2->len;
+ } else {
+ dev_err(dev, "unsupported trace rsc version %d\n", ver);

If we use "type" to describe your 64-bit-da-trace then this sanity check
would have been taken care of by the core.

+ return -EINVAL;
+ }
- if (sizeof(*rsc) > avail) {
+ if (rsc_size > avail) {
dev_err(dev, "trace rsc is truncated\n");
return -EINVAL;
}
/* make sure reserved bytes are zeroes */
- if (rsc->reserved) {
- dev_err(dev, "trace rsc has non zero reserved bytes\n");
+ if (reserved) {
+ dev_err(dev, "trace rsc has non zero reserved bytes, value = 0x%x\n",
+ reserved);
return -EINVAL;
}
@@ -632,8 +656,8 @@ static int rproc_handle_trace(struct rproc *rproc, struct fw_rsc_trace *rsc,
return -ENOMEM;
/* set the trace buffer dma properties */
- trace->trace_mem.len = rsc->len;
- trace->trace_mem.da = rsc->da;
+ trace->trace_mem.len = len;
+ trace->trace_mem.da = da;
/* set pointer on rproc device */
trace->rproc = rproc;
@@ -652,8 +676,8 @@ static int rproc_handle_trace(struct rproc *rproc, struct fw_rsc_trace *rsc,
rproc->num_traces++;
- dev_dbg(dev, "%s added: da 0x%x, len 0x%x\n",
- name, rsc->da, rsc->len);
+ dev_dbg(dev, "%s added: da 0x%llx, len 0x%x\n",
+ name, da, len);
return 0;
}
diff --git a/drivers/remoteproc/remoteproc_debugfs.c b/drivers/remoteproc/remoteproc_debugfs.c
index 3560eed7a360..ff43736db45a 100644
--- a/drivers/remoteproc/remoteproc_debugfs.c
+++ b/drivers/remoteproc/remoteproc_debugfs.c
@@ -192,7 +192,8 @@ static int rproc_rsc_table_show(struct seq_file *seq, void *p)
struct resource_table *table = rproc->table_ptr;
struct fw_rsc_carveout *c;
struct fw_rsc_devmem *d;
- struct fw_rsc_trace *t;
+ struct fw_rsc_trace *t1;
+ struct fw_rsc_trace2 *t2;
struct fw_rsc_vdev *v;
int i, j;
@@ -205,6 +206,7 @@ static int rproc_rsc_table_show(struct seq_file *seq, void *p)
int offset = table->offset[i];
struct fw_rsc_hdr *hdr = (void *)table + offset;
void *rsc = (void *)hdr + sizeof(*hdr);
+ u16 ver = hdr->st.v;
switch (hdr->st.t) {
case RSC_CARVEOUT:
@@ -230,13 +232,32 @@ static int rproc_rsc_table_show(struct seq_file *seq, void *p)
seq_printf(seq, " Name %s\n\n", d->name);
break;
case RSC_TRACE:
- t = rsc;
- seq_printf(seq, "Entry %d is of type %s\n",
- i, types[hdr->st.t]);
- seq_printf(seq, " Device Address 0x%x\n", t->da);
- seq_printf(seq, " Length 0x%x Bytes\n", t->len);
- seq_printf(seq, " Reserved (should be zero) [%d]\n", t->reserved);
- seq_printf(seq, " Name %s\n\n", t->name);
+ if (ver == 0) {

Again, this is a switch, here in a switch. Just defining a new
RSC_TRACE64 type would reduce the amount of code here...

OK.


+ t1 = rsc;
+ seq_printf(seq, "Entry %d is version %d of type %s\n",
+ i, ver, types[hdr->st.t]);
+ seq_printf(seq, " Device Address 0x%x\n",
+ t1->da);
+ seq_printf(seq, " Length 0x%x Bytes\n",
+ t1->len);
+ seq_printf(seq, " Reserved (should be zero) [%d]\n",
+ t1->reserved);
+ seq_printf(seq, " Name %s\n\n", t1->name);
+ } else if (ver == 1) {
+ t2 = rsc;
+ seq_printf(seq, "Entry %d is version %d of type %s\n",
+ i, ver, types[hdr->st.t]);
+ seq_printf(seq, " Device Address 0x%llx\n",
+ t2->da);
+ seq_printf(seq, " Length 0x%x Bytes\n",
+ t2->len);
+ seq_printf(seq, " Reserved (should be zero) [%d]\n",
+ t2->reserved);
+ seq_printf(seq, " Name %s\n\n", t2->name);
+ } else {
+ seq_printf(seq, "Entry %d is an unsupported version %d of type %s\n",
+ i, ver, types[hdr->st.t]);
+ }
break;
case RSC_VDEV:
v = rsc;
diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h
index 526d3cb45e37..3b3bea42f8b1 100644
--- a/include/linux/remoteproc.h
+++ b/include/linux/remoteproc.h
@@ -243,6 +243,32 @@ struct fw_rsc_trace {
u8 name[32];
} __packed;
+/**
+ * struct fw_rsc_trace2 - trace buffer declaration supporting 64-bits
+ * @padding: initial padding after type field for aligned 64-bit access
+ * @da: device address (64-bit)
+ * @len: length (in bytes)
+ * @reserved: reserved (must be zero)
+ * @name: human-readable name of the trace buffer
+ *
+ * This resource entry is an enhanced version of the fw_rsc_trace resourec entry
+ * and the provides equivalent functionality but designed for 64-bit remote
+ * processors.
+ *
+ * @da specifies the device address of the buffer, @len specifies
+ * its size, and @name may contain a human readable name of the trace buffer.
+ *
+ * After booting the remote processor, the trace buffers are exposed to the
+ * user via debugfs entries (called trace0, trace1, etc..).
+ */
+struct fw_rsc_trace2 {

Sounds more like fw_rsc_trace64 to me - in particular since the version
of trace2 is 1...

Yeah, will rename this.


+ u32 padding;
+ u64 da;
+ u32 len;
+ u32 reserved;

What's the purpose of this reserved field?

Partly to make sure the entire resource is aligned on an 8-byte, and partly copied over from fw_rsc_trace entry. I guess 32-bits is already large enough of a size for trace entries irrespective of 32-bit or 64-bit traces, so I doubt if we want to make the len field also a u64.

regards
Suman


Regards,
Bjorn

+ u8 name[32];
+} __packed;
+
/**
* struct fw_rsc_vdev_vring - vring descriptor entry
* @da: device address
--
2.23.0