Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 666 insertions, 0 deletions

diff --git a/sound/soc/sof/ipc4-mtrace.c b/sound/soc/sof/ipc4-mtrace.c
new file mode 100644
index 000000000..cfd999b42
--- /dev/null
+++ b/sound/soc/sof/ipc4-mtrace.c
@@ -0,0 +1,666 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright(c) 2022 Intel Corporation
+
+#include <linux/debugfs.h>
+#include <linux/sched/signal.h>
+#include <linux/sched/clock.h>
+#include <sound/sof/ipc4/header.h>
+#include "sof-priv.h"
+#include "ipc4-priv.h"
+
+/*
+ * debug info window is organized in 16 (equal sized) pages:
+ *
+ *	------------------------
+ *	| Page0  - descriptors |
+ *	------------------------
+ *	| Page1  - slot0       |
+ *	------------------------
+ *	| Page2  - slot1       |
+ *	------------------------
+ *	|         ...          |
+ *	------------------------
+ *	| Page14  - slot13     |
+ *	------------------------
+ *	| Page15  - slot14     |
+ *	------------------------
+ *
+ * The slot size == page size
+ *
+ * The first page contains descriptors for the remaining 15 cores
+ * The slot descriptor is:
+ * u32 res_id;
+ * u32 type;
+ * u32 vma;
+ *
+ * Log buffer slots have the following layout:
+ * u32 host_read_ptr;
+ * u32 dsp_write_ptr;
+ * u8 buffer[];
+ *
+ * The two pointers are offsets within the buffer.
+ */
+
+#define FW_EPOCH_DELTA				11644473600LL
+
+#define MAX_ALLOWED_LIBRARIES			16
+
+#define SOF_IPC4_INVALID_SLOT_OFFSET		0xffffffff
+
+ /* for debug and critical types */
+#define SOF_MTRACE_SLOT_CORE_MASK		GENMASK(7, 0)
+#define SOF_MTRACE_SLOT_TYPE_MASK		GENMASK(31, 8)
+
+#define DEFAULT_AGING_TIMER_PERIOD_MS		0x100
+#define DEFAULT_FIFO_FULL_TIMER_PERIOD_MS	0x1000
+
+/* ipc4 log level and source definitions for logs_priorities_mask */
+#define SOF_MTRACE_LOG_LEVEL_CRITICAL		BIT(0)
+#define SOF_MTRACE_LOG_LEVEL_ERROR		BIT(1)
+#define SOF_MTRACE_LOG_LEVEL_WARNING		BIT(2)
+#define SOF_MTRACE_LOG_LEVEL_INFO		BIT(3)
+#define SOF_MTRACE_LOG_LEVEL_VERBOSE		BIT(4)
+#define SOF_MTRACE_LOG_SOURCE_INFRA		BIT(5) /* log source 0 */
+#define SOF_MTRACE_LOG_SOURCE_HAL		BIT(6)
+#define SOF_MTRACE_LOG_SOURCE_MODULE		BIT(7)
+#define SOF_MTRACE_LOG_SOURCE_AUDIO		BIT(8)
+#define SOF_MTRACE_LOG_SOURCE_SCHEDULER		BIT(9)
+#define SOF_MTRACE_LOG_SOURCE_ULP_INFRA		BIT(10)
+#define SOF_MTRACE_LOG_SOURCE_ULP_MODULE	BIT(11)
+#define SOF_MTRACE_LOG_SOURCE_VISION		BIT(12) /* log source 7 */
+#define DEFAULT_LOGS_PRIORITIES_MASK	(SOF_MTRACE_LOG_LEVEL_CRITICAL | \
+					 SOF_MTRACE_LOG_LEVEL_ERROR |	 \
+					 SOF_MTRACE_LOG_LEVEL_WARNING |	 \
+					 SOF_MTRACE_LOG_LEVEL_INFO |	 \
+					 SOF_MTRACE_LOG_SOURCE_INFRA |	 \
+					 SOF_MTRACE_LOG_SOURCE_HAL |	 \
+					 SOF_MTRACE_LOG_SOURCE_MODULE |	 \
+					 SOF_MTRACE_LOG_SOURCE_AUDIO)
+
+struct sof_log_state_info {
+	u32 aging_timer_period;
+	u32 fifo_full_timer_period;
+	u32 enable;
+	u32 logs_priorities_mask[MAX_ALLOWED_LIBRARIES];
+} __packed;
+
+enum sof_mtrace_state {
+	SOF_MTRACE_DISABLED,
+	SOF_MTRACE_INITIALIZING,
+	SOF_MTRACE_ENABLED,
+};
+
+struct sof_mtrace_core_data {
+	struct snd_sof_dev *sdev;
+
+	int id;
+	u32 slot_offset;
+	void *log_buffer;
+	struct mutex buffer_lock; /* for log_buffer alloc/free */
+	u32 host_read_ptr;
+	u32 dsp_write_ptr;
+	/* pos update IPC arrived before the slot offset is known, queried */
+	bool delayed_pos_update;
+	wait_queue_head_t trace_sleep;
+};
+
+struct sof_mtrace_priv {
+	struct snd_sof_dev *sdev;
+	enum sof_mtrace_state mtrace_state;
+	struct sof_log_state_info state_info;
+
+	struct sof_mtrace_core_data cores[];
+};
+
+static int sof_ipc4_mtrace_dfs_open(struct inode *inode, struct file *file)
+{
+	struct sof_mtrace_core_data *core_data = inode->i_private;
+	int ret;
+
+	guard(mutex)(&core_data->buffer_lock);
+
+	if (core_data->log_buffer)
+		return -EBUSY;
+
+	ret = debugfs_file_get(file->f_path.dentry);
+	if (unlikely(ret))
+		return ret;
+
+	core_data->log_buffer = kmalloc(SOF_IPC4_DEBUG_SLOT_SIZE, GFP_KERNEL);
+	if (!core_data->log_buffer) {
+		debugfs_file_put(file->f_path.dentry);
+		return -ENOMEM;
+	}
+
+	ret = simple_open(inode, file);
+	if (ret) {
+		kfree(core_data->log_buffer);
+		debugfs_file_put(file->f_path.dentry);
+	}
+
+	return ret;
+}
+
+static bool sof_wait_mtrace_avail(struct sof_mtrace_core_data *core_data)
+{
+	wait_queue_entry_t wait;
+
+	/* data immediately available */
+	if (core_data->host_read_ptr != core_data->dsp_write_ptr)
+		return true;
+
+	/* wait for available trace data from FW */
+	init_waitqueue_entry(&wait, current);
+	set_current_state(TASK_INTERRUPTIBLE);
+	add_wait_queue(&core_data->trace_sleep, &wait);
+
+	if (!signal_pending(current)) {
+		/* set timeout to max value, no error code */
+		schedule_timeout(MAX_SCHEDULE_TIMEOUT);
+	}
+	remove_wait_queue(&core_data->trace_sleep, &wait);
+
+	if (core_data->host_read_ptr != core_data->dsp_write_ptr)
+		return true;
+
+	return false;
+}
+
+static ssize_t sof_ipc4_mtrace_dfs_read(struct file *file, char __user *buffer,
+					size_t count, loff_t *ppos)
+{
+	struct sof_mtrace_core_data *core_data = file->private_data;
+	u32 log_buffer_offset, log_buffer_size, read_ptr, write_ptr;
+	struct snd_sof_dev *sdev = core_data->sdev;
+	struct sof_mtrace_priv *priv = sdev->fw_trace_data;
+	void *log_buffer = core_data->log_buffer;
+	loff_t lpos = *ppos;
+	u32 avail;
+	int ret;
+
+	/* check pos and count */
+	if (lpos < 0)
+		return -EINVAL;
+	if (!count || count < sizeof(avail))
+		return 0;
+
+	/* get available count based on current host offset */
+	if (!sof_wait_mtrace_avail(core_data)) {
+		/* No data available */
+		avail = 0;
+		if (copy_to_user(buffer, &avail, sizeof(avail)))
+			return -EFAULT;
+
+		return 0;
+	}
+
+	if (core_data->slot_offset == SOF_IPC4_INVALID_SLOT_OFFSET)
+		return 0;
+
+	/* The log data buffer starts after the two pointer in the slot */
+	log_buffer_offset =  core_data->slot_offset + (sizeof(u32) * 2);
+	/* The log data size excludes the pointers */
+	log_buffer_size = SOF_IPC4_DEBUG_SLOT_SIZE - (sizeof(u32) * 2);
+
+	read_ptr = core_data->host_read_ptr;
+	write_ptr = core_data->dsp_write_ptr;
+
+	if (read_ptr < write_ptr)
+		avail = write_ptr - read_ptr;
+	else
+		avail = log_buffer_size - read_ptr + write_ptr;
+
+	if (!avail)
+		return 0;
+
+	if (avail > log_buffer_size)
+		avail = log_buffer_size;
+
+	/* Need space for the initial u32 of the avail */
+	if (avail > count - sizeof(avail))
+		avail = count - sizeof(avail);
+
+	if (sof_debug_check_flag(SOF_DBG_PRINT_DMA_POSITION_UPDATE_LOGS))
+		dev_dbg(sdev->dev,
+			"core%d, host read: %#x, dsp write: %#x, avail: %#x\n",
+			core_data->id, read_ptr, write_ptr, avail);
+
+	if (read_ptr < write_ptr) {
+		/* Read data between read pointer and write pointer */
+		sof_mailbox_read(sdev, log_buffer_offset + read_ptr, log_buffer, avail);
+	} else {
+		/* read from read pointer to end of the slot */
+		sof_mailbox_read(sdev, log_buffer_offset + read_ptr, log_buffer,
+				 avail - write_ptr);
+		/* read from slot start to write pointer */
+		if (write_ptr)
+			sof_mailbox_read(sdev, log_buffer_offset,
+					 (u8 *)(log_buffer) + avail - write_ptr,
+					 write_ptr);
+	}
+
+	/* first write the number of bytes we have gathered */
+	ret = copy_to_user(buffer, &avail, sizeof(avail));
+	if (ret)
+		return -EFAULT;
+
+	/* Followed by the data itself */
+	ret = copy_to_user(buffer + sizeof(avail), log_buffer, avail);
+	if (ret)
+		return -EFAULT;
+
+	/* Update the host_read_ptr in the slot for this core */
+	read_ptr += avail;
+	if (read_ptr >= log_buffer_size)
+		read_ptr -= log_buffer_size;
+	sof_mailbox_write(sdev, core_data->slot_offset, &read_ptr, sizeof(read_ptr));
+
+	/* Only update the host_read_ptr if mtrace is enabled */
+	if (priv->mtrace_state != SOF_MTRACE_DISABLED)
+		core_data->host_read_ptr = read_ptr;
+
+	/*
+	 * Ask for a new buffer from user space for the next chunk, not
+	 * streaming due to the heading number of bytes value.
+	 */
+	*ppos += count;
+
+	return count;
+}
+
+static int sof_ipc4_mtrace_dfs_release(struct inode *inode, struct file *file)
+{
+	struct sof_mtrace_core_data *core_data = inode->i_private;
+
+	debugfs_file_put(file->f_path.dentry);
+
+	scoped_guard(mutex, &core_data->buffer_lock) {
+		kfree(core_data->log_buffer);
+		core_data->log_buffer = NULL;
+	}
+
+	return 0;
+}
+
+static const struct file_operations sof_dfs_mtrace_fops = {
+	.open = sof_ipc4_mtrace_dfs_open,
+	.read = sof_ipc4_mtrace_dfs_read,
+	.llseek = default_llseek,
+	.release = sof_ipc4_mtrace_dfs_release,
+
+	.owner = THIS_MODULE,
+};
+
+static ssize_t sof_ipc4_priority_mask_dfs_read(struct file *file, char __user *to,
+					       size_t count, loff_t *ppos)
+{
+	struct sof_mtrace_priv *priv = file->private_data;
+	int i, ret, offset, remaining;
+	char *buf;
+
+	/*
+	 * one entry (14 char + new line = 15):
+	 * " 0: 000001ef"
+	 *
+	 * 16 * 15 + 1 = 241
+	 */
+	buf = kzalloc(241, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	for (i = 0; i < MAX_ALLOWED_LIBRARIES; i++) {
+		offset = strlen(buf);
+		remaining = 241 - offset;
+		snprintf(buf + offset, remaining, "%2d: 0x%08x\n", i,
+			 priv->state_info.logs_priorities_mask[i]);
+	}
+
+	ret = simple_read_from_buffer(to, count, ppos, buf, strlen(buf));
+
+	kfree(buf);
+	return ret;
+}
+
+static ssize_t sof_ipc4_priority_mask_dfs_write(struct file *file,
+						const char __user *from,
+						size_t count, loff_t *ppos)
+{
+	struct sof_mtrace_priv *priv = file->private_data;
+	unsigned int id;
+	char *buf;
+	u32 mask;
+	int ret;
+
+	/*
+	 * To update Nth mask entry, write:
+	 * "N,0x1234" or "N,1234" to the debugfs file
+	 * The mask will be interpreted as hexadecimal number
+	 */
+	buf = memdup_user_nul(from, count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	ret = sscanf(buf, "%u,0x%x", &id, &mask);
+	if (ret != 2) {
+		ret = sscanf(buf, "%u,%x", &id, &mask);
+		if (ret != 2) {
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	if (id >= MAX_ALLOWED_LIBRARIES) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	priv->state_info.logs_priorities_mask[id] = mask;
+	ret = count;
+
+out:
+	kfree(buf);
+	return ret;
+}
+
+static const struct file_operations sof_dfs_priority_mask_fops = {
+	.open = simple_open,
+	.read = sof_ipc4_priority_mask_dfs_read,
+	.write = sof_ipc4_priority_mask_dfs_write,
+	.llseek = default_llseek,
+
+	.owner = THIS_MODULE,
+};
+
+static int mtrace_debugfs_create(struct snd_sof_dev *sdev)
+{
+	struct sof_mtrace_priv *priv = sdev->fw_trace_data;
+	struct dentry *dfs_root;
+	char dfs_name[100];
+	int i;
+
+	dfs_root = debugfs_create_dir("mtrace", sdev->debugfs_root);
+	if (IS_ERR_OR_NULL(dfs_root))
+		return 0;
+
+	/* Create files for the logging parameters */
+	debugfs_create_u32("aging_timer_period", 0644, dfs_root,
+			   &priv->state_info.aging_timer_period);
+	debugfs_create_u32("fifo_full_timer_period", 0644, dfs_root,
+			   &priv->state_info.fifo_full_timer_period);
+	debugfs_create_file("logs_priorities_mask", 0644, dfs_root, priv,
+			    &sof_dfs_priority_mask_fops);
+
+	/* Separate log files per core */
+	for (i = 0; i < sdev->num_cores; i++) {
+		snprintf(dfs_name, sizeof(dfs_name), "core%d", i);
+		debugfs_create_file(dfs_name, 0444, dfs_root, &priv->cores[i],
+				    &sof_dfs_mtrace_fops);
+	}
+
+	return 0;
+}
+
+static int ipc4_mtrace_enable(struct snd_sof_dev *sdev)
+{
+	struct sof_mtrace_priv *priv = sdev->fw_trace_data;
+	const struct sof_ipc_ops *iops = sdev->ipc->ops;
+	struct sof_ipc4_msg msg;
+	u64 system_time;
+	int ret;
+
+	if (priv->mtrace_state != SOF_MTRACE_DISABLED)
+		return 0;
+
+	msg.primary = SOF_IPC4_MSG_TARGET(SOF_IPC4_MODULE_MSG);
+	msg.primary |= SOF_IPC4_MSG_DIR(SOF_IPC4_MSG_REQUEST);
+	msg.primary |= SOF_IPC4_MOD_ID(SOF_IPC4_MOD_INIT_BASEFW_MOD_ID);
+	msg.primary |= SOF_IPC4_MOD_INSTANCE(SOF_IPC4_MOD_INIT_BASEFW_INSTANCE_ID);
+	msg.extension = SOF_IPC4_MOD_EXT_MSG_PARAM_ID(SOF_IPC4_FW_PARAM_SYSTEM_TIME);
+
+	/*
+	 * local_clock() is used to align with dmesg, so both kernel and firmware logs have
+	 * the same base and a minor delta due to the IPC. system time is in us format but
+	 * local_clock() returns the time in ns, so convert to ns.
+	 */
+	system_time = div64_u64(local_clock(), NSEC_PER_USEC);
+	msg.data_size = sizeof(system_time);
+	msg.data_ptr = &system_time;
+	ret = iops->set_get_data(sdev, &msg, msg.data_size, true);
+	if (ret)
+		return ret;
+
+	msg.extension = SOF_IPC4_MOD_EXT_MSG_PARAM_ID(SOF_IPC4_FW_PARAM_ENABLE_LOGS);
+
+	priv->state_info.enable = 1;
+
+	msg.data_size = sizeof(priv->state_info);
+	msg.data_ptr = &priv->state_info;
+
+	priv->mtrace_state = SOF_MTRACE_INITIALIZING;
+	ret = iops->set_get_data(sdev, &msg, msg.data_size, true);
+	if (ret) {
+		priv->mtrace_state = SOF_MTRACE_DISABLED;
+		return ret;
+	}
+
+	priv->mtrace_state = SOF_MTRACE_ENABLED;
+
+	return 0;
+}
+
+static void ipc4_mtrace_disable(struct snd_sof_dev *sdev)
+{
+	struct sof_mtrace_priv *priv = sdev->fw_trace_data;
+	const struct sof_ipc_ops *iops = sdev->ipc->ops;
+	struct sof_ipc4_msg msg;
+	int i;
+
+	if (priv->mtrace_state == SOF_MTRACE_DISABLED)
+		return;
+
+	msg.primary = SOF_IPC4_MSG_TARGET(SOF_IPC4_MODULE_MSG);
+	msg.primary |= SOF_IPC4_MSG_DIR(SOF_IPC4_MSG_REQUEST);
+	msg.primary |= SOF_IPC4_MOD_ID(SOF_IPC4_MOD_INIT_BASEFW_MOD_ID);
+	msg.primary |= SOF_IPC4_MOD_INSTANCE(SOF_IPC4_MOD_INIT_BASEFW_INSTANCE_ID);
+	msg.extension = SOF_IPC4_MOD_EXT_MSG_PARAM_ID(SOF_IPC4_FW_PARAM_ENABLE_LOGS);
+
+	priv->state_info.enable = 0;
+
+	msg.data_size = sizeof(priv->state_info);
+	msg.data_ptr = &priv->state_info;
+	iops->set_get_data(sdev, &msg, msg.data_size, true);
+
+	priv->mtrace_state = SOF_MTRACE_DISABLED;
+
+	for (i = 0; i < sdev->num_cores; i++) {
+		struct sof_mtrace_core_data *core_data = &priv->cores[i];
+
+		core_data->host_read_ptr = 0;
+		core_data->dsp_write_ptr = 0;
+		wake_up(&core_data->trace_sleep);
+	}
+}
+
+/*
+ * Each DSP core logs to a dedicated slot.
+ * Parse the slot descriptors at debug_box offset to find the debug log slots
+ * and map them to cores.
+ * There are 15 slots and therefore 15 descriptors to check (MAX_MTRACE_SLOTS)
+ */
+static void sof_mtrace_find_core_slots(struct snd_sof_dev *sdev)
+{
+	struct sof_mtrace_priv *priv = sdev->fw_trace_data;
+	struct sof_mtrace_core_data *core_data;
+	u32 slot_desc_type_offset, type, core;
+	int i;
+
+	for (i = 0; i < SOF_IPC4_MAX_DEBUG_SLOTS; i++) {
+		/* The type is the second u32 in the slot descriptor */
+		slot_desc_type_offset = sdev->debug_box.offset;
+		slot_desc_type_offset += SOF_IPC4_DEBUG_DESCRIPTOR_SIZE * i + sizeof(u32);
+		sof_mailbox_read(sdev, slot_desc_type_offset, &type, sizeof(type));
+
+		if ((type & SOF_MTRACE_SLOT_TYPE_MASK) == SOF_IPC4_DEBUG_SLOT_DEBUG_LOG) {
+			core = type & SOF_MTRACE_SLOT_CORE_MASK;
+
+			if (core >= sdev->num_cores) {
+				dev_dbg(sdev->dev, "core%u is invalid for slot%d\n",
+					core, i);
+				continue;
+			}
+
+			core_data = &priv->cores[core];
+			/*
+			 * The area reserved for descriptors have the same size
+			 * as a slot.
+			 * In other words: slot0 starts at
+			 * debug_box + SOF_MTRACE_SLOT_SIZE offset
+			 */
+			core_data->slot_offset = sdev->debug_box.offset;
+			core_data->slot_offset += SOF_IPC4_DEBUG_SLOT_SIZE * (i + 1);
+			dev_dbg(sdev->dev, "slot%d is used for core%u\n", i, core);
+			if (core_data->delayed_pos_update) {
+				sof_ipc4_mtrace_update_pos(sdev, core);
+				core_data->delayed_pos_update = false;
+			}
+		} else if (type) {
+			dev_dbg(sdev->dev, "slot%d is not a log slot (%#x)\n", i, type);
+		}
+	}
+}
+
+static int ipc4_mtrace_init(struct snd_sof_dev *sdev)
+{
+	struct sof_ipc4_fw_data *ipc4_data = sdev->private;
+	struct sof_mtrace_priv *priv;
+	int i, ret;
+
+	if (sdev->fw_trace_data) {
+		dev_err(sdev->dev, "fw_trace_data has been already allocated\n");
+		return -EBUSY;
+	}
+
+	if (!ipc4_data->mtrace_log_bytes ||
+	    ipc4_data->mtrace_type != SOF_IPC4_MTRACE_INTEL_CAVS_2) {
+		sdev->fw_trace_is_supported = false;
+		return 0;
+	}
+
+	priv = devm_kzalloc(sdev->dev, struct_size(priv, cores, sdev->num_cores),
+			    GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	sdev->fw_trace_data = priv;
+
+	/* Set initial values for mtrace parameters */
+	priv->state_info.aging_timer_period = DEFAULT_AGING_TIMER_PERIOD_MS;
+	priv->state_info.fifo_full_timer_period = DEFAULT_FIFO_FULL_TIMER_PERIOD_MS;
+	/* Only enable basefw logs initially (index 0 is always basefw) */
+	priv->state_info.logs_priorities_mask[0] = DEFAULT_LOGS_PRIORITIES_MASK;
+
+	for (i = 0; i < sdev->num_cores; i++) {
+		struct sof_mtrace_core_data *core_data = &priv->cores[i];
+
+		init_waitqueue_head(&core_data->trace_sleep);
+		mutex_init(&core_data->buffer_lock);
+		core_data->sdev = sdev;
+		core_data->id = i;
+	}
+
+	ret = ipc4_mtrace_enable(sdev);
+	if (ret) {
+		/*
+		 * Mark firmware tracing as not supported and return 0 to not
+		 * block the whole audio stack
+		 */
+		sdev->fw_trace_is_supported = false;
+		dev_dbg(sdev->dev, "initialization failed, fw tracing is disabled\n");
+		return 0;
+	}
+
+	sof_mtrace_find_core_slots(sdev);
+
+	ret = mtrace_debugfs_create(sdev);
+	if (ret)
+		ipc4_mtrace_disable(sdev);
+
+	return ret;
+}
+
+static void ipc4_mtrace_free(struct snd_sof_dev *sdev)
+{
+	ipc4_mtrace_disable(sdev);
+}
+
+static int sof_ipc4_mtrace_update_pos_all_cores(struct snd_sof_dev *sdev)
+{
+	int i;
+
+	for (i = 0; i < sdev->num_cores; i++)
+		sof_ipc4_mtrace_update_pos(sdev, i);
+
+	return 0;
+}
+
+int sof_ipc4_mtrace_update_pos(struct snd_sof_dev *sdev, int core)
+{
+	struct sof_mtrace_priv *priv = sdev->fw_trace_data;
+	struct sof_mtrace_core_data *core_data;
+
+	if (!sdev->fw_trace_is_supported ||
+	    priv->mtrace_state == SOF_MTRACE_DISABLED)
+		return 0;
+
+	if (core >= sdev->num_cores)
+		return -EINVAL;
+
+	core_data = &priv->cores[core];
+
+	if (core_data->slot_offset == SOF_IPC4_INVALID_SLOT_OFFSET) {
+		core_data->delayed_pos_update = true;
+		return 0;
+	}
+
+	/* Read out the dsp_write_ptr from the slot for this core */
+	sof_mailbox_read(sdev, core_data->slot_offset + sizeof(u32),
+			 &core_data->dsp_write_ptr, 4);
+	core_data->dsp_write_ptr -= core_data->dsp_write_ptr % 4;
+
+	if (sof_debug_check_flag(SOF_DBG_PRINT_DMA_POSITION_UPDATE_LOGS))
+		dev_dbg(sdev->dev, "core%d, host read: %#x, dsp write: %#x",
+			core, core_data->host_read_ptr, core_data->dsp_write_ptr);
+
+	wake_up(&core_data->trace_sleep);
+
+	return 0;
+}
+
+static void ipc4_mtrace_fw_crashed(struct snd_sof_dev *sdev)
+{
+	/*
+	 * The DSP might not be able to send SOF_IPC4_NOTIFY_LOG_BUFFER_STATUS
+	 * messages anymore, so check the log buffer status on all
+	 * cores and process any pending messages.
+	 */
+	sof_ipc4_mtrace_update_pos_all_cores(sdev);
+}
+
+static int ipc4_mtrace_resume(struct snd_sof_dev *sdev)
+{
+	return ipc4_mtrace_enable(sdev);
+}
+
+static void ipc4_mtrace_suspend(struct snd_sof_dev *sdev, pm_message_t pm_state)
+{
+	ipc4_mtrace_disable(sdev);
+}
+
+const struct sof_ipc_fw_tracing_ops ipc4_mtrace_ops = {
+	.init = ipc4_mtrace_init,
+	.free = ipc4_mtrace_free,
+	.fw_crashed = ipc4_mtrace_fw_crashed,
+	.suspend = ipc4_mtrace_suspend,
+	.resume = ipc4_mtrace_resume,
+};