tools: Initial version of IPC4 tx message logger using eBPF

The ipc4-msg-trace.bt script will tap into the entry of
sof_ipc4_log_header() which is always called but only prints if dynamic
debugging is enabled. It's parameter list is not expected to be changed.

The bpftrace must be installed to be able to use the script
sudo pacman -S bpftrace
sudo emerge -a bpftrace
sudo apt install bpftrace
sudo dnf install bpftrace

To use the script:
sudo ./tools/sof-ipc4-msg-trace.bt
or
sudo bpftrace tools/sof-ipc4-msg-trace.bt

It will start logging the sent messages (including payloads) and received
notification with exception of 0x1b060000 - trace update.

To stop the logging, just terminate the script with CTRL+C

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@linux.intel.com>

Author: ujfalusi

tools/README.md

@@ -34,6 +34,8 @@
 * sof-process-state.sh
 <br> Shows the current state of a given process
 
+* eBPF (directory)
+<br> Enhanced Berkeley Packet Filter (eBPF) scripts for kernel tracing
 
 Topologies
 ----------

tools/eBPF/README.md

@@ -0,0 +1,28 @@
+# Enhanced Berkeley Packet Filter (eBPF) scripts
+
+bpftrace must be installed to be able to use eBPF scripts:
+
+```
+sudo apt install bpftrace
+sudo dnf install bpftrace
+sudo pacman -S bpftrace
+sudo emerge -a bpftrace
+...
+```
+
+**Note**: the distro provided bpftrace might be old, in that case the tool can be downloaded from [https://github.com/bpftrace/bpftrace/releases](URL)
+
+## ipc4-msg-trace.bt
+
+The script will tap onto the entry of sof_ipc4_log_header() to log IPC messages.
+It will start logging the sent messages (including payloads) and received notification with exception of 0x1b060000 - trace update.
+
+### To use the script:
+
+```
+sudo ./tools/sof-ipc4-msg-trace.bt
+or
+sudo bpftrace tools/sof-ipc4-msg-trace.bt
+```
+
+To stop the logging, just terminate the script with CTRL+C

tools/eBPF/ipc4-msg-trace.bt

@@ -0,0 +1,82 @@
+#!/usr/bin/bpftrace
+
+struct sof_ipc4_msg {
+	union {
+		unsigned long header_u64;
+		struct {
+			unsigned int primary;
+			unsigned int extension;
+		};
+	};
+
+	unsigned long data_size;
+	void *data_ptr;
+};
+
+BEGIN
+{
+	printf("SOF IPC4 tx message logging. Ctrl-C to end.\n\n");
+}
+
+/*
+ * Log the sent IPC4 messages, ignoring the 0x1b060000 notification
+ * from firmware (trace update)
+ * The message payload is printed as 32bit words, arranged by 4 words/line.
+ * In case the payload lenght is not aligned to 32bit words, the remaining 1-3
+ * bytes are printed as bytes (unlikely, just for safety)
+ */
+kprobe:sof_ipc4_log_header {
+	$msg = (struct sof_ipc4_msg *)arg2;
+
+	if ($msg->primary != 0x1b060000 && arg3 == 1 && $msg->data_size != 0) {
+		printf("%s : 0x%x|0x%x [data size:: %llu]\n", str(arg1),
+		       $msg->primary, $msg->extension, $msg->data_size);
+
+		if (!strcontains(str(arg1), "done")) {
+			$count = (int64) $msg->data_size;
+			$ptr = (uint32*) $msg->data_ptr;
+
+			printf("Message payload:\n");
+
+			$line = 0;
+			while ($line < 500) {
+				printf("%08x:", $line * 16);
+
+				$word = 0;
+				while ($word < 4) {
+					if ($count >= 4) {
+						printf(" %08x", *$ptr);
+						$count -= 4;
+					} else {
+						printf("%rh", buf($ptr, $count));
+						$count = 0;
+					}
+
+					if ($count == 0) {
+						break;
+					}
+
+					$ptr++;
+					$word++;
+				}
+
+				printf("\n");
+
+				if ($count == 0) {
+					break;
+				}
+
+				$line++;
+			}
+		} else {
+			printf("\n");
+		}
+	} else if ($msg->primary != 0x1b060000) {
+		printf("%s : 0x%x|0x%x\n", str(arg1), $msg->primary, $msg->extension);
+
+		if (strcontains(str(arg1), "done")) {
+			printf("\n");
+		}
+	}
+}
+