linux/drivers/gpu/drm/xe/xe_devcoredump.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2023 Intel Corporation
 */

#include "xe_devcoredump.h"
#include "xe_devcoredump_types.h"

#include <linux/ascii85.h>
#include <linux/devcoredump.h>
#include <generated/utsrelease.h>

#include <drm/drm_managed.h>

#include "xe_device.h"
#include "xe_exec_queue.h"
#include "xe_force_wake.h"
#include "xe_gt.h"
#include "xe_gt_printk.h"
#include "xe_guc_capture.h"
#include "xe_guc_ct.h"
#include "xe_guc_log.h"
#include "xe_guc_submit.h"
#include "xe_hw_engine.h"
#include "xe_module.h"
#include "xe_pm.h"
#include "xe_sched_job.h"
#include "xe_vm.h"

/**
 * DOC: Xe device coredump
 *
 * Xe uses dev_coredump infrastructure for exposing the crash errors in a
 * standardized way. Once a crash occurs, devcoredump exposes a temporary
 * node under ``/sys/class/devcoredump/devcd<m>/``. The same node is also
 * accessible in ``/sys/class/drm/card<n>/device/devcoredump/``. The
 * ``failing_device`` symlink points to the device that crashed and created the
 * coredump.
 *
 * The following characteristics are observed by xe when creating a device
 * coredump:
 *
 * **Snapshot at hang**:
 *   The 'data' file contains a snapshot of the HW and driver states at the time
 *   the hang happened. Due to the driver recovering from resets/crashes, it may
 *   not correspond to the state of the system when the file is read by
 *   userspace.
 *
 * **Coredump release**:
 *   After a coredump is generated, it stays in kernel memory until released by
 *   userpace by writing anything to it, or after an internal timer expires. The
 *   exact timeout may vary and should not be relied upon. Example to release
 *   a coredump:
 *
 *   .. code-block:: shell
 *
 *	$ > /sys/class/drm/card0/device/devcoredump/data
 *
 * **First failure only**:
 *   In general, the first hang is the most critical one since the following
 *   hangs can be a consequence of the initial hang. For this reason a snapshot
 *   is taken only for the first failure. Until the devcoredump is released by
 *   userspace or kernel, all subsequent hangs do not override the snapshot nor
 *   create new ones. Devcoredump has a delayed work queue that will eventually
 *   delete the file node and free all the dump information.
 */

#ifdef CONFIG_DEV_COREDUMP

/* 1 hour timeout */
#define XE_COREDUMP_TIMEOUT_JIFFIES (60 * 60 * HZ)

static struct xe_device *coredump_to_xe(const struct xe_devcoredump *coredump)
{
	return container_of(coredump, struct xe_device, devcoredump);
}

static struct xe_guc *exec_queue_to_guc(struct xe_exec_queue *q)
{
	return &q->gt->uc.guc;
}

static ssize_t __xe_devcoredump_read(char *buffer, size_t count,
				     struct xe_devcoredump *coredump)
{
	struct xe_device *xe;
	struct xe_devcoredump_snapshot *ss;
	struct drm_printer p;
	struct drm_print_iterator iter;
	struct timespec64 ts;
	int i;

	xe = coredump_to_xe(coredump);
	ss = &coredump->snapshot;

	iter.data = buffer;
	iter.start = 0;
	iter.remain = count;

	p = drm_coredump_printer(&iter);

	drm_puts(&p, "**** Xe Device Coredump ****\n");
	drm_printf(&p, "Reason: %s\n", ss->reason);
	drm_puts(&p, "kernel: " UTS_RELEASE "\n");
	drm_puts(&p, "module: " KBUILD_MODNAME "\n");

	ts = ktime_to_timespec64(ss->snapshot_time);
	drm_printf(&p, "Snapshot time: %lld.%09ld\n", ts.tv_sec, ts.tv_nsec);
	ts = ktime_to_timespec64(ss->boot_time);
	drm_printf(&p, "Uptime: %lld.%09ld\n", ts.tv_sec, ts.tv_nsec);
	drm_printf(&p, "Process: %s [%d]\n", ss->process_name, ss->pid);
	xe_device_snapshot_print(xe, &p);

	drm_printf(&p, "\n**** GT #%d ****\n", ss->gt->info.id);
	drm_printf(&p, "\tTile: %d\n", ss->gt->tile->id);

	drm_puts(&p, "\n**** GuC Log ****\n");
	xe_guc_log_snapshot_print(ss->guc.log, &p);
	drm_puts(&p, "\n**** GuC CT ****\n");
	xe_guc_ct_snapshot_print(ss->guc.ct, &p);

	/*
	 * Don't add a new section header here because the mesa debug decoder
	 * tool expects the context information to be in the 'GuC CT' section.
	 */
	/* drm_puts(&p, "\n**** Contexts ****\n"); */
	xe_guc_exec_queue_snapshot_print(ss->ge, &p);

	drm_puts(&p, "\n**** Job ****\n");
	xe_sched_job_snapshot_print(ss->job, &p);

	drm_puts(&p, "\n**** HW Engines ****\n");
	for (i = 0; i < XE_NUM_HW_ENGINES; i++)
		if (ss->hwe[i])
			xe_engine_snapshot_print(ss->hwe[i], &p);

	drm_puts(&p, "\n**** VM state ****\n");
	xe_vm_snapshot_print(ss->vm, &p);

	return count - iter.remain;
}

static void xe_devcoredump_snapshot_free(struct xe_devcoredump_snapshot *ss)
{
	int i;

	kfree(ss->reason);
	ss->reason = NULL;

	xe_guc_log_snapshot_free(ss->guc.log);
	ss->guc.log = NULL;

	xe_guc_ct_snapshot_free(ss->guc.ct);
	ss->guc.ct = NULL;

	xe_guc_capture_put_matched_nodes(&ss->gt->uc.guc);
	ss->matched_node = NULL;

	xe_guc_exec_queue_snapshot_free(ss->ge);
	ss->ge = NULL;

	xe_sched_job_snapshot_free(ss->job);
	ss->job = NULL;

	for (i = 0; i < XE_NUM_HW_ENGINES; i++)
		if (ss->hwe[i]) {
			xe_hw_engine_snapshot_free(ss->hwe[i]);
			ss->hwe[i] = NULL;
		}

	xe_vm_snapshot_free(ss->vm);
	ss->vm = NULL;
}

static ssize_t xe_devcoredump_read(char *buffer, loff_t offset,
				   size_t count, void *data, size_t datalen)
{
	struct xe_devcoredump *coredump = data;
	struct xe_devcoredump_snapshot *ss;
	ssize_t byte_copied;

	if (!coredump)
		return -ENODEV;

	ss = &coredump->snapshot;

	/* Ensure delayed work is captured before continuing */
	flush_work(&ss->work);

	mutex_lock(&coredump->lock);

	if (!ss->read.buffer) {
		mutex_unlock(&coredump->lock);
		return -ENODEV;
	}

	if (offset >= ss->read.size) {
		mutex_unlock(&coredump->lock);
		return 0;
	}

	byte_copied = count < ss->read.size - offset ? count :
		ss->read.size - offset;
	memcpy(buffer, ss->read.buffer + offset, byte_copied);

	mutex_unlock(&coredump->lock);

	return byte_copied;
}

static void xe_devcoredump_free(void *data)
{
	struct xe_devcoredump *coredump = data;

	/* Our device is gone. Nothing to do... */
	if (!data || !coredump_to_xe(coredump))
		return;

	cancel_work_sync(&coredump->snapshot.work);

	mutex_lock(&coredump->lock);

	xe_devcoredump_snapshot_free(&coredump->snapshot);
	kvfree(coredump->snapshot.read.buffer);

	/* To prevent stale data on next snapshot, clear everything */
	memset(&coredump->snapshot, 0, sizeof(coredump->snapshot));
	coredump->captured = false;
	drm_info(&coredump_to_xe(coredump)->drm,
		 "Xe device coredump has been deleted.\n");

	mutex_unlock(&coredump->lock);
}

static void xe_devcoredump_deferred_snap_work(struct work_struct *work)
{
	struct xe_devcoredump_snapshot *ss = container_of(work, typeof(*ss), work);
	struct xe_devcoredump *coredump = container_of(ss, typeof(*coredump), snapshot);
	struct xe_device *xe = coredump_to_xe(coredump);
	unsigned int fw_ref;

	/*
	 * NB: Despite passing a GFP_ flags parameter here, more allocations are done
	 * internally using GFP_KERNEL expliictly. Hence this call must be in the worker
	 * thread and not in the initial capture call.
	 */
	dev_coredumpm_timeout(gt_to_xe(ss->gt)->drm.dev, THIS_MODULE, coredump, 0, GFP_KERNEL,
			      xe_devcoredump_read, xe_devcoredump_free,
			      XE_COREDUMP_TIMEOUT_JIFFIES);

	xe_pm_runtime_get(xe);

	/* keep going if fw fails as we still want to save the memory and SW data */
	fw_ref = xe_force_wake_get(gt_to_fw(ss->gt), XE_FORCEWAKE_ALL);
	if (!xe_force_wake_ref_has_domain(fw_ref, XE_FORCEWAKE_ALL))
		xe_gt_info(ss->gt, "failed to get forcewake for coredump capture\n");
	xe_vm_snapshot_capture_delayed(ss->vm);
	xe_guc_exec_queue_snapshot_capture_delayed(ss->ge);
	xe_force_wake_put(gt_to_fw(ss->gt), fw_ref);

	xe_pm_runtime_put(xe);

	/* Calculate devcoredump size */
	ss->read.size = __xe_devcoredump_read(NULL, INT_MAX, coredump);

	ss->read.buffer = kvmalloc(ss->read.size, GFP_USER);
	if (!ss->read.buffer)
		return;

	__xe_devcoredump_read(ss->read.buffer, ss->read.size, coredump);
	xe_devcoredump_snapshot_free(ss);
}

static void devcoredump_snapshot(struct xe_devcoredump *coredump,
				 struct xe_exec_queue *q,
				 struct xe_sched_job *job)
{
	struct xe_devcoredump_snapshot *ss = &coredump->snapshot;
	struct xe_guc *guc = exec_queue_to_guc(q);
	u32 adj_logical_mask = q->logical_mask;
	u32 width_mask = (0x1 << q->width) - 1;
	const char *process_name = "no process";

	unsigned int fw_ref;
	bool cookie;
	int i;

	ss->snapshot_time = ktime_get_real();
	ss->boot_time = ktime_get_boottime();

	if (q->vm && q->vm->xef) {
		process_name = q->vm->xef->process_name;
		ss->pid = q->vm->xef->pid;
	}

	strscpy(ss->process_name, process_name);

	ss->gt = q->gt;
	INIT_WORK(&ss->work, xe_devcoredump_deferred_snap_work);

	cookie = dma_fence_begin_signalling();
	for (i = 0; q->width > 1 && i < XE_HW_ENGINE_MAX_INSTANCE;) {
		if (adj_logical_mask & BIT(i)) {
			adj_logical_mask |= width_mask << i;
			i += q->width;
		} else {
			++i;
		}
	}

	/* keep going if fw fails as we still want to save the memory and SW data */
	fw_ref = xe_force_wake_get(gt_to_fw(q->gt), XE_FORCEWAKE_ALL);

	ss->guc.log = xe_guc_log_snapshot_capture(&guc->log, true);
	ss->guc.ct = xe_guc_ct_snapshot_capture(&guc->ct);
	ss->ge = xe_guc_exec_queue_snapshot_capture(q);
	if (job)
		ss->job = xe_sched_job_snapshot_capture(job);
	ss->vm = xe_vm_snapshot_capture(q->vm);

	xe_engine_snapshot_capture_for_queue(q);

	queue_work(system_unbound_wq, &ss->work);

	xe_force_wake_put(gt_to_fw(q->gt), fw_ref);
	dma_fence_end_signalling(cookie);
}

/**
 * xe_devcoredump - Take the required snapshots and initialize coredump device.
 * @q: The faulty xe_exec_queue, where the issue was detected.
 * @job: The faulty xe_sched_job, where the issue was detected.
 * @fmt: Printf format + args to describe the reason for the core dump
 *
 * This function should be called at the crash time within the serialized
 * gt_reset. It is skipped if we still have the core dump device available
 * with the information of the 'first' snapshot.
 */
__printf(3, 4)
void xe_devcoredump(struct xe_exec_queue *q, struct xe_sched_job *job, const char *fmt, ...)
{
	struct xe_device *xe = gt_to_xe(q->gt);
	struct xe_devcoredump *coredump = &xe->devcoredump;
	va_list varg;

	mutex_lock(&coredump->lock);

	if (coredump->captured) {
		drm_dbg(&xe->drm, "Multiple hangs are occurring, but only the first snapshot was taken\n");
		mutex_unlock(&coredump->lock);
		return;
	}

	coredump->captured = true;

	va_start(varg, fmt);
	coredump->snapshot.reason = kvasprintf(GFP_ATOMIC, fmt, varg);
	va_end(varg);

	devcoredump_snapshot(coredump, q, job);

	drm_info(&xe->drm, "Xe device coredump has been created\n");
	drm_info(&xe->drm, "Check your /sys/class/drm/card%d/device/devcoredump/data\n",
		 xe->drm.primary->index);

	mutex_unlock(&coredump->lock);
}

static void xe_driver_devcoredump_fini(void *arg)
{
	struct drm_device *drm = arg;

	dev_coredump_put(drm->dev);
}

int xe_devcoredump_init(struct xe_device *xe)
{
	int err;

	err = drmm_mutex_init(&xe->drm, &xe->devcoredump.lock);
	if (err)
		return err;

	if (IS_ENABLED(CONFIG_LOCKDEP)) {
		fs_reclaim_acquire(GFP_KERNEL);
		might_lock(&xe->devcoredump.lock);
		fs_reclaim_release(GFP_KERNEL);
	}

	return devm_add_action_or_reset(xe->drm.dev, xe_driver_devcoredump_fini, &xe->drm);
}

#endif

/**
 * xe_print_blob_ascii85 - print a BLOB to some useful location in ASCII85
 *
 * The output is split to multiple lines because some print targets, e.g. dmesg
 * cannot handle arbitrarily long lines. Note also that printing to dmesg in
 * piece-meal fashion is not possible, each separate call to drm_puts() has a
 * line-feed automatically added! Therefore, the entire output line must be
 * constructed in a local buffer first, then printed in one atomic output call.
 *
 * There is also a scheduler yield call to prevent the 'task has been stuck for
 * 120s' kernel hang check feature from firing when printing to a slow target
 * such as dmesg over a serial port.
 *
 * TODO: Add compression prior to the ASCII85 encoding to shrink huge buffers down.
 *
 * @p: the printer object to output to
 * @prefix: optional prefix to add to output string
 * @blob: the Binary Large OBject to dump out
 * @offset: offset in bytes to skip from the front of the BLOB, must be a multiple of sizeof(u32)
 * @size: the size in bytes of the BLOB, must be a multiple of sizeof(u32)
 */
void xe_print_blob_ascii85(struct drm_printer *p, const char *prefix,
			   const void *blob, size_t offset, size_t size)
{
	const u32 *blob32 = (const u32 *)blob;
	char buff[ASCII85_BUFSZ], *line_buff;
	size_t line_pos = 0;

	/*
	 * Splitting blobs across multiple lines is not compatible with the mesa
	 * debug decoder tool. Note that even dropping the explicit '\n' below
	 * doesn't help because the GuC log is so big some underlying implementation
	 * still splits the lines at 512K characters. So just bail completely for
	 * the moment.
	 */
	return;

#define DMESG_MAX_LINE_LEN	800
#define MIN_SPACE		(ASCII85_BUFSZ + 2)		/* 85 + "\n\0" */

	if (size & 3)
		drm_printf(p, "Size not word aligned: %zu", size);
	if (offset & 3)
		drm_printf(p, "Offset not word aligned: %zu", size);

	line_buff = kzalloc(DMESG_MAX_LINE_LEN, GFP_KERNEL);
	if (IS_ERR_OR_NULL(line_buff)) {
		drm_printf(p, "Failed to allocate line buffer: %pe", line_buff);
		return;
	}

	blob32 += offset / sizeof(*blob32);
	size /= sizeof(*blob32);

	if (prefix) {
		strscpy(line_buff, prefix, DMESG_MAX_LINE_LEN - MIN_SPACE - 2);
		line_pos = strlen(line_buff);

		line_buff[line_pos++] = ':';
		line_buff[line_pos++] = ' ';
	}

	while (size--) {
		u32 val = *(blob32++);

		strscpy(line_buff + line_pos, ascii85_encode(val, buff),
			DMESG_MAX_LINE_LEN - line_pos);
		line_pos += strlen(line_buff + line_pos);

		if ((line_pos + MIN_SPACE) >= DMESG_MAX_LINE_LEN) {
			line_buff[line_pos++] = '\n';
			line_buff[line_pos++] = 0;

			drm_puts(p, line_buff);

			line_pos = 0;

			/* Prevent 'stuck thread' time out errors */
			cond_resched();
		}
	}

	if (line_pos) {
		line_buff[line_pos++] = '\n';
		line_buff[line_pos++] = 0;

		drm_puts(p, line_buff);
	}

	kfree(line_buff);

#undef MIN_SPACE
#undef DMESG_MAX_LINE_LEN
}