Bluetooth: Add support for hci devcoredump

Add devcoredump APIs to hci core so that drivers only have to provide
the dump skbs instead of managing the synchronization and timeouts.

The devcoredump APIs should be used in the following manner:
 - hci_devcoredump_init is called to allocate the dump.
 - hci_devcoredump_append is called to append any skbs with dump data
   OR hci_devcoredump_append_pattern is called to insert a pattern.
 - hci_devcoredump_complete is called when all dump packets have been
   sent OR hci_devcoredump_abort is called to indicate an error and
   cancel an ongoing dump collection.

The high level APIs just prepare some skbs with the appropriate data and
queue it for the dump to process. Packets part of the crashdump can be
intercepted in the driver in interrupt context and forwarded directly to
the devcoredump APIs.

Internally, there are 5 states for the dump: idle, active, complete,
abort and timeout. A devcoredump will only be in active state after it
has been initialized. Once active, it accepts data to be appended,
patterns to be inserted (i.e. memset) and a completion event or an abort
event to generate a devcoredump. The timeout is initialized at the same
time the dump is initialized (defaulting to 10s) and will be cleared
either when the timeout occurs or the dump is complete or aborted.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Manish Mandlik <mmandlik@google.com>
Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

1 files changed, 535 insertions, 0 deletions

diff --git a/net/bluetooth/coredump.c b/net/bluetooth/coredump.c
new file mode 100644
index 000000000000..08fa98505454
--- /dev/null
+++ b/net/bluetooth/coredump.c
@@ -0,0 +1,535 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023 Google Corporation
+ */
+
+#include <linux/devcoredump.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+enum hci_devcoredump_pkt_type {
+	HCI_DEVCOREDUMP_PKT_INIT,
+	HCI_DEVCOREDUMP_PKT_SKB,
+	HCI_DEVCOREDUMP_PKT_PATTERN,
+	HCI_DEVCOREDUMP_PKT_COMPLETE,
+	HCI_DEVCOREDUMP_PKT_ABORT,
+};
+
+struct hci_devcoredump_skb_cb {
+	u16 pkt_type;
+};
+
+struct hci_devcoredump_skb_pattern {
+	u8 pattern;
+	u32 len;
+} __packed;
+
+#define hci_dmp_cb(skb)	((struct hci_devcoredump_skb_cb *)((skb)->cb))
+
+#define DBG_UNEXPECTED_STATE() \
+	bt_dev_dbg(hdev, \
+		   "Unexpected packet (%d) for state (%d). ", \
+		   hci_dmp_cb(skb)->pkt_type, hdev->dump.state)
+
+#define MAX_DEVCOREDUMP_HDR_SIZE	512	/* bytes */
+
+static int hci_devcd_update_hdr_state(char *buf, size_t size, int state)
+{
+	int len = 0;
+
+	if (!buf)
+		return 0;
+
+	len = scnprintf(buf, size, "Bluetooth devcoredump\nState: %d\n", state);
+
+	return len + 1; /* scnprintf adds \0 at the end upon state rewrite */
+}
+
+/* Call with hci_dev_lock only. */
+static int hci_devcd_update_state(struct hci_dev *hdev, int state)
+{
+	bt_dev_dbg(hdev, "Updating devcoredump state from %d to %d.",
+		   hdev->dump.state, state);
+
+	hdev->dump.state = state;
+
+	return hci_devcd_update_hdr_state(hdev->dump.head,
+					  hdev->dump.alloc_size, state);
+}
+
+static int hci_devcd_mkheader(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	char dump_start[] = "--- Start dump ---\n";
+	char hdr[80];
+	int hdr_len;
+
+	hdr_len = hci_devcd_update_hdr_state(hdr, sizeof(hdr),
+					     HCI_DEVCOREDUMP_IDLE);
+	skb_put_data(skb, hdr, hdr_len);
+
+	if (hdev->dump.dmp_hdr)
+		hdev->dump.dmp_hdr(hdev, skb);
+
+	skb_put_data(skb, dump_start, strlen(dump_start));
+
+	return skb->len;
+}
+
+/* Do not call with hci_dev_lock since this calls driver code. */
+static void hci_devcd_notify(struct hci_dev *hdev, int state)
+{
+	if (hdev->dump.notify_change)
+		hdev->dump.notify_change(hdev, state);
+}
+
+/* Call with hci_dev_lock only. */
+void hci_devcd_reset(struct hci_dev *hdev)
+{
+	hdev->dump.head = NULL;
+	hdev->dump.tail = NULL;
+	hdev->dump.alloc_size = 0;
+
+	hci_devcd_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
+
+	cancel_delayed_work(&hdev->dump.dump_timeout);
+	skb_queue_purge(&hdev->dump.dump_q);
+}
+
+/* Call with hci_dev_lock only. */
+static void hci_devcd_free(struct hci_dev *hdev)
+{
+	if (hdev->dump.head)
+		vfree(hdev->dump.head);
+
+	hci_devcd_reset(hdev);
+}
+
+/* Call with hci_dev_lock only. */
+static int hci_devcd_alloc(struct hci_dev *hdev, u32 size)
+{
+	hdev->dump.head = vmalloc(size);
+	if (!hdev->dump.head)
+		return -ENOMEM;
+
+	hdev->dump.alloc_size = size;
+	hdev->dump.tail = hdev->dump.head;
+	hdev->dump.end = hdev->dump.head + size;
+
+	hci_devcd_update_state(hdev, HCI_DEVCOREDUMP_IDLE);
+
+	return 0;
+}
+
+/* Call with hci_dev_lock only. */
+static bool hci_devcd_copy(struct hci_dev *hdev, char *buf, u32 size)
+{
+	if (hdev->dump.tail + size > hdev->dump.end)
+		return false;
+
+	memcpy(hdev->dump.tail, buf, size);
+	hdev->dump.tail += size;
+
+	return true;
+}
+
+/* Call with hci_dev_lock only. */
+static bool hci_devcd_memset(struct hci_dev *hdev, u8 pattern, u32 len)
+{
+	if (hdev->dump.tail + len > hdev->dump.end)
+		return false;
+
+	memset(hdev->dump.tail, pattern, len);
+	hdev->dump.tail += len;
+
+	return true;
+}
+
+/* Call with hci_dev_lock only. */
+static int hci_devcd_prepare(struct hci_dev *hdev, u32 dump_size)
+{
+	struct sk_buff *skb;
+	int dump_hdr_size;
+	int err = 0;
+
+	skb = alloc_skb(MAX_DEVCOREDUMP_HDR_SIZE, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	dump_hdr_size = hci_devcd_mkheader(hdev, skb);
+
+	if (hci_devcd_alloc(hdev, dump_hdr_size + dump_size)) {
+		err = -ENOMEM;
+		goto hdr_free;
+	}
+
+	/* Insert the device header */
+	if (!hci_devcd_copy(hdev, skb->data, skb->len)) {
+		bt_dev_err(hdev, "Failed to insert header");
+		hci_devcd_free(hdev);
+
+		err = -ENOMEM;
+		goto hdr_free;
+	}
+
+hdr_free:
+	kfree_skb(skb);
+
+	return err;
+}
+
+static void hci_devcd_handle_pkt_init(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	u32 *dump_size;
+
+	if (hdev->dump.state != HCI_DEVCOREDUMP_IDLE) {
+		DBG_UNEXPECTED_STATE();
+		return;
+	}
+
+	if (skb->len != sizeof(*dump_size)) {
+		bt_dev_dbg(hdev, "Invalid dump init pkt");
+		return;
+	}
+
+	dump_size = skb_pull_data(skb, sizeof(*dump_size));
+	if (!*dump_size) {
+		bt_dev_err(hdev, "Zero size dump init pkt");
+		return;
+	}
+
+	if (hci_devcd_prepare(hdev, *dump_size)) {
+		bt_dev_err(hdev, "Failed to prepare for dump");
+		return;
+	}
+
+	hci_devcd_update_state(hdev, HCI_DEVCOREDUMP_ACTIVE);
+	queue_delayed_work(hdev->workqueue, &hdev->dump.dump_timeout,
+			   hdev->dump.timeout);
+}
+
+static void hci_devcd_handle_pkt_skb(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
+		DBG_UNEXPECTED_STATE();
+		return;
+	}
+
+	if (!hci_devcd_copy(hdev, skb->data, skb->len))
+		bt_dev_dbg(hdev, "Failed to insert skb");
+}
+
+static void hci_devcd_handle_pkt_pattern(struct hci_dev *hdev,
+					 struct sk_buff *skb)
+{
+	struct hci_devcoredump_skb_pattern *pattern;
+
+	if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
+		DBG_UNEXPECTED_STATE();
+		return;
+	}
+
+	if (skb->len != sizeof(*pattern)) {
+		bt_dev_dbg(hdev, "Invalid pattern skb");
+		return;
+	}
+
+	pattern = skb_pull_data(skb, sizeof(*pattern));
+
+	if (!hci_devcd_memset(hdev, pattern->pattern, pattern->len))
+		bt_dev_dbg(hdev, "Failed to set pattern");
+}
+
+static void hci_devcd_handle_pkt_complete(struct hci_dev *hdev,
+					  struct sk_buff *skb)
+{
+	u32 dump_size;
+
+	if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
+		DBG_UNEXPECTED_STATE();
+		return;
+	}
+
+	hci_devcd_update_state(hdev, HCI_DEVCOREDUMP_DONE);
+	dump_size = hdev->dump.tail - hdev->dump.head;
+
+	bt_dev_dbg(hdev, "complete with size %u (expect %zu)", dump_size,
+		   hdev->dump.alloc_size);
+
+	dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size, GFP_KERNEL);
+}
+
+static void hci_devcd_handle_pkt_abort(struct hci_dev *hdev,
+				       struct sk_buff *skb)
+{
+	u32 dump_size;
+
+	if (hdev->dump.state != HCI_DEVCOREDUMP_ACTIVE) {
+		DBG_UNEXPECTED_STATE();
+		return;
+	}
+
+	hci_devcd_update_state(hdev, HCI_DEVCOREDUMP_ABORT);
+	dump_size = hdev->dump.tail - hdev->dump.head;
+
+	bt_dev_dbg(hdev, "aborted with size %u (expect %zu)", dump_size,
+		   hdev->dump.alloc_size);
+
+	/* Emit a devcoredump with the available data */
+	dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size, GFP_KERNEL);
+}
+
+/* Bluetooth devcoredump state machine.
+ *
+ * Devcoredump states:
+ *
+ *      HCI_DEVCOREDUMP_IDLE: The default state.
+ *
+ *      HCI_DEVCOREDUMP_ACTIVE: A devcoredump will be in this state once it has
+ *              been initialized using hci_devcd_init(). Once active, the driver
+ *              can append data using hci_devcd_append() or insert a pattern
+ *              using hci_devcd_append_pattern().
+ *
+ *      HCI_DEVCOREDUMP_DONE: Once the dump collection is complete, the drive
+ *              can signal the completion using hci_devcd_complete(). A
+ *              devcoredump is generated indicating the completion event and
+ *              then the state machine is reset to the default state.
+ *
+ *      HCI_DEVCOREDUMP_ABORT: The driver can cancel ongoing dump collection in
+ *              case of any error using hci_devcd_abort(). A devcoredump is
+ *              still generated with the available data indicating the abort
+ *              event and then the state machine is reset to the default state.
+ *
+ *      HCI_DEVCOREDUMP_TIMEOUT: A timeout timer for HCI_DEVCOREDUMP_TIMEOUT sec
+ *              is started during devcoredump initialization. Once the timeout
+ *              occurs, the driver is notified, a devcoredump is generated with
+ *              the available data indicating the timeout event and then the
+ *              state machine is reset to the default state.
+ *
+ * The driver must register using hci_devcd_register() before using the hci
+ * devcoredump APIs.
+ */
+void hci_devcd_rx(struct work_struct *work)
+{
+	struct hci_dev *hdev = container_of(work, struct hci_dev, dump.dump_rx);
+	struct sk_buff *skb;
+	int start_state;
+
+	while ((skb = skb_dequeue(&hdev->dump.dump_q))) {
+		/* Return if timeout occurs. The timeout handler function
+		 * hci_devcd_timeout() will report the available dump data.
+		 */
+		if (hdev->dump.state == HCI_DEVCOREDUMP_TIMEOUT) {
+			kfree_skb(skb);
+			return;
+		}
+
+		hci_dev_lock(hdev);
+		start_state = hdev->dump.state;
+
+		switch (hci_dmp_cb(skb)->pkt_type) {
+		case HCI_DEVCOREDUMP_PKT_INIT:
+			hci_devcd_handle_pkt_init(hdev, skb);
+			break;
+
+		case HCI_DEVCOREDUMP_PKT_SKB:
+			hci_devcd_handle_pkt_skb(hdev, skb);
+			break;
+
+		case HCI_DEVCOREDUMP_PKT_PATTERN:
+			hci_devcd_handle_pkt_pattern(hdev, skb);
+			break;
+
+		case HCI_DEVCOREDUMP_PKT_COMPLETE:
+			hci_devcd_handle_pkt_complete(hdev, skb);
+			break;
+
+		case HCI_DEVCOREDUMP_PKT_ABORT:
+			hci_devcd_handle_pkt_abort(hdev, skb);
+			break;
+
+		default:
+			bt_dev_dbg(hdev, "Unknown packet (%d) for state (%d). ",
+				   hci_dmp_cb(skb)->pkt_type, hdev->dump.state);
+			break;
+		}
+
+		hci_dev_unlock(hdev);
+		kfree_skb(skb);
+
+		/* Notify the driver about any state changes before resetting
+		 * the state machine
+		 */
+		if (start_state != hdev->dump.state)
+			hci_devcd_notify(hdev, hdev->dump.state);
+
+		/* Reset the state machine if the devcoredump is complete */
+		hci_dev_lock(hdev);
+		if (hdev->dump.state == HCI_DEVCOREDUMP_DONE ||
+		    hdev->dump.state == HCI_DEVCOREDUMP_ABORT)
+			hci_devcd_reset(hdev);
+		hci_dev_unlock(hdev);
+	}
+}
+EXPORT_SYMBOL(hci_devcd_rx);
+
+void hci_devcd_timeout(struct work_struct *work)
+{
+	struct hci_dev *hdev = container_of(work, struct hci_dev,
+					    dump.dump_timeout.work);
+	u32 dump_size;
+
+	hci_devcd_notify(hdev, HCI_DEVCOREDUMP_TIMEOUT);
+
+	hci_dev_lock(hdev);
+
+	cancel_work(&hdev->dump.dump_rx);
+
+	hci_devcd_update_state(hdev, HCI_DEVCOREDUMP_TIMEOUT);
+
+	dump_size = hdev->dump.tail - hdev->dump.head;
+	bt_dev_dbg(hdev, "timeout with size %u (expect %zu)", dump_size,
+		   hdev->dump.alloc_size);
+
+	/* Emit a devcoredump with the available data */
+	dev_coredumpv(&hdev->dev, hdev->dump.head, dump_size, GFP_KERNEL);
+
+	hci_devcd_reset(hdev);
+
+	hci_dev_unlock(hdev);
+}
+EXPORT_SYMBOL(hci_devcd_timeout);
+
+int hci_devcd_register(struct hci_dev *hdev, coredump_t coredump,
+		       dmp_hdr_t dmp_hdr, notify_change_t notify_change)
+{
+	/* Driver must implement coredump() and dmp_hdr() functions for
+	 * bluetooth devcoredump. The coredump() should trigger a coredump
+	 * event on the controller when the device's coredump sysfs entry is
+	 * written to. The dmp_hdr() should create a dump header to identify
+	 * the controller/fw/driver info.
+	 */
+	if (!coredump || !dmp_hdr)
+		return -EINVAL;
+
+	hci_dev_lock(hdev);
+	hdev->dump.coredump = coredump;
+	hdev->dump.dmp_hdr = dmp_hdr;
+	hdev->dump.notify_change = notify_change;
+	hdev->dump.supported = true;
+	hdev->dump.timeout = DEVCOREDUMP_TIMEOUT;
+	hci_dev_unlock(hdev);
+
+	return 0;
+}
+EXPORT_SYMBOL(hci_devcd_register);
+
+static inline bool hci_devcd_enabled(struct hci_dev *hdev)
+{
+	return hdev->dump.supported;
+}
+
+int hci_devcd_init(struct hci_dev *hdev, u32 dump_size)
+{
+	struct sk_buff *skb;
+
+	if (!hci_devcd_enabled(hdev))
+		return -EOPNOTSUPP;
+
+	skb = alloc_skb(sizeof(dump_size), GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_INIT;
+	skb_put_data(skb, &dump_size, sizeof(dump_size));
+
+	skb_queue_tail(&hdev->dump.dump_q, skb);
+	queue_work(hdev->workqueue, &hdev->dump.dump_rx);
+
+	return 0;
+}
+EXPORT_SYMBOL(hci_devcd_init);
+
+int hci_devcd_append(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	if (!skb)
+		return -ENOMEM;
+
+	if (!hci_devcd_enabled(hdev)) {
+		kfree_skb(skb);
+		return -EOPNOTSUPP;
+	}
+
+	hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_SKB;
+
+	skb_queue_tail(&hdev->dump.dump_q, skb);
+	queue_work(hdev->workqueue, &hdev->dump.dump_rx);
+
+	return 0;
+}
+EXPORT_SYMBOL(hci_devcd_append);
+
+int hci_devcd_append_pattern(struct hci_dev *hdev, u8 pattern, u32 len)
+{
+	struct hci_devcoredump_skb_pattern p;
+	struct sk_buff *skb;
+
+	if (!hci_devcd_enabled(hdev))
+		return -EOPNOTSUPP;
+
+	skb = alloc_skb(sizeof(p), GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	p.pattern = pattern;
+	p.len = len;
+
+	hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_PATTERN;
+	skb_put_data(skb, &p, sizeof(p));
+
+	skb_queue_tail(&hdev->dump.dump_q, skb);
+	queue_work(hdev->workqueue, &hdev->dump.dump_rx);
+
+	return 0;
+}
+EXPORT_SYMBOL(hci_devcd_append_pattern);
+
+int hci_devcd_complete(struct hci_dev *hdev)
+{
+	struct sk_buff *skb;
+
+	if (!hci_devcd_enabled(hdev))
+		return -EOPNOTSUPP;
+
+	skb = alloc_skb(0, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_COMPLETE;
+
+	skb_queue_tail(&hdev->dump.dump_q, skb);
+	queue_work(hdev->workqueue, &hdev->dump.dump_rx);
+
+	return 0;
+}
+EXPORT_SYMBOL(hci_devcd_complete);
+
+int hci_devcd_abort(struct hci_dev *hdev)
+{
+	struct sk_buff *skb;
+
+	if (!hci_devcd_enabled(hdev))
+		return -EOPNOTSUPP;
+
+	skb = alloc_skb(0, GFP_ATOMIC);
+	if (!skb)
+		return -ENOMEM;
+
+	hci_dmp_cb(skb)->pkt_type = HCI_DEVCOREDUMP_PKT_ABORT;
+
+	skb_queue_tail(&hdev->dump.dump_q, skb);
+	queue_work(hdev->workqueue, &hdev->dump.dump_rx);
+
+	return 0;
+}
+EXPORT_SYMBOL(hci_devcd_abort);