i915_gpu_error.c

/*
 * Copyright (c) 2008 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *    Keith Packard <keithp@keithp.com>
 *    Mika Kuoppala <mika.kuoppala@intel.com>
 *
 */

#include <linux/ascii85.h>
#include <linux/nmi.h>
#include <linux/scatterlist.h>
#include <linux/stop_machine.h>
#include <linux/utsname.h>
#include <linux/zlib.h>

#include <drm/drm_print.h>

#include "i915_gpu_error.h"
#include "i915_drv.h"

static inline const struct intel_engine_cs *
engine_lookup(const struct drm_i915_private *i915, unsigned int id)
{
	if (id >= I915_NUM_ENGINES)
		return NULL;

	return i915->engine[id];
}

static inline const char *
__engine_name(const struct intel_engine_cs *engine)
{
	return engine ? engine->name : "";
}

static const char *
engine_name(const struct drm_i915_private *i915, unsigned int id)
{
	return __engine_name(engine_lookup(i915, id));
}

static const char *tiling_flag(int tiling)
{
	switch (tiling) {
	default:
	case I915_TILING_NONE: return "";
	case I915_TILING_X: return " X";
	case I915_TILING_Y: return " Y";
	}
}

static const char *dirty_flag(int dirty)
{
	return dirty ? " dirty" : "";
}

static const char *purgeable_flag(int purgeable)
{
	return purgeable ? " purgeable" : "";
}

static void __sg_set_buf(struct scatterlist *sg,
			 void *addr, unsigned int len, loff_t it)
{
	sg->page_link = (unsigned long)virt_to_page(addr);
	sg->offset = offset_in_page(addr);
	sg->length = len;
	sg->dma_address = it;
}

static bool __i915_error_grow(struct drm_i915_error_state_buf *e, size_t len)
{
	if (!len)
		return false;

	if (e->bytes + len + 1 <= e->size)
		return true;

	if (e->bytes) {
		__sg_set_buf(e->cur++, e->buf, e->bytes, e->iter);
		e->iter += e->bytes;
		e->buf = NULL;
		e->bytes = 0;
	}

	if (e->cur == e->end) {
		struct scatterlist *sgl;

		sgl = (typeof(sgl))__get_free_page(GFP_KERNEL);
		if (!sgl) {
			e->err = -ENOMEM;
			return false;
		}

		if (e->cur) {
			e->cur->offset = 0;
			e->cur->length = 0;
			e->cur->page_link =
				(unsigned long)sgl | SG_CHAIN;
		} else {
			e->sgl = sgl;
		}

		e->cur = sgl;
		e->end = sgl + SG_MAX_SINGLE_ALLOC - 1;
	}

	e->size = ALIGN(len + 1, SZ_64K);
	e->buf = kmalloc(e->size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
	if (!e->buf) {
		e->size = PAGE_ALIGN(len + 1);
		e->buf = kmalloc(e->size, GFP_KERNEL);
	}
	if (!e->buf) {
		e->err = -ENOMEM;
		return false;
	}

	return true;
}

__printf(2, 0)
static void i915_error_vprintf(struct drm_i915_error_state_buf *e,
			       const char *fmt, va_list args)
{
	va_list ap;
	int len;

	if (e->err)
		return;

	va_copy(ap, args);
	len = vsnprintf(NULL, 0, fmt, ap);
	va_end(ap);
	if (len <= 0) {
		e->err = len;
		return;
	}

	if (!__i915_error_grow(e, len))
		return;

	GEM_BUG_ON(e->bytes >= e->size);
	len = vscnprintf(e->buf + e->bytes, e->size - e->bytes, fmt, args);
	if (len < 0) {
		e->err = len;
		return;
	}
	e->bytes += len;
}

static void i915_error_puts(struct drm_i915_error_state_buf *e, const char *str)
{
	unsigned len;

	if (e->err || !str)
		return;

	len = strlen(str);
	if (!__i915_error_grow(e, len))
		return;

	GEM_BUG_ON(e->bytes + len > e->size);
	memcpy(e->buf + e->bytes, str, len);
	e->bytes += len;
}

#define err_printf(e, ...) i915_error_printf(e, __VA_ARGS__)
#define err_puts(e, s) i915_error_puts(e, s)

static void __i915_printfn_error(struct drm_printer *p, struct va_format *vaf)
{
	i915_error_vprintf(p->arg, vaf->fmt, *vaf->va);
}

static inline struct drm_printer
i915_error_printer(struct drm_i915_error_state_buf *e)
{
	struct drm_printer p = {
		.printfn = __i915_printfn_error,
		.arg = e,
	};
	return p;
}

#ifdef CONFIG_DRM_I915_COMPRESS_ERROR

struct compress {
	struct z_stream_s zstream;
	void *tmp;
};

static bool compress_init(struct compress *c)
{
	struct z_stream_s *zstream = memset(&c->zstream, 0, sizeof(c->zstream));

	zstream->workspace =
		kmalloc(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
			GFP_ATOMIC | __GFP_NOWARN);
	if (!zstream->workspace)
		return false;

	if (zlib_deflateInit(zstream, Z_DEFAULT_COMPRESSION) != Z_OK) {
		kfree(zstream->workspace);
		return false;
	}

	c->tmp = NULL;
	if (i915_has_memcpy_from_wc())
		c->tmp = (void *)__get_free_page(GFP_ATOMIC | __GFP_NOWARN);

	return true;
}

static void *compress_next_page(struct drm_i915_error_object *dst)
{
	unsigned long page;

	if (dst->page_count >= dst->num_pages)
		return ERR_PTR(-ENOSPC);

	page = __get_free_page(GFP_ATOMIC | __GFP_NOWARN);
	if (!page)
		return ERR_PTR(-ENOMEM);

	return dst->pages[dst->page_count++] = (void *)page;
}

static int compress_page(struct compress *c,
			 void *src,
			 struct drm_i915_error_object *dst)
{
	struct z_stream_s *zstream = &c->zstream;

	zstream->next_in = src;
	if (c->tmp && i915_memcpy_from_wc(c->tmp, src, PAGE_SIZE))
		zstream->next_in = c->tmp;
	zstream->avail_in = PAGE_SIZE;

	do {
		if (zstream->avail_out == 0) {
			zstream->next_out = compress_next_page(dst);
			if (IS_ERR(zstream->next_out))
				return PTR_ERR(zstream->next_out);

			zstream->avail_out = PAGE_SIZE;
		}

		if (zlib_deflate(zstream, Z_NO_FLUSH) != Z_OK)
			return -EIO;

		touch_nmi_watchdog();
	} while (zstream->avail_in);

	/* Fallback to uncompressed if we increase size? */
	if (0 && zstream->total_out > zstream->total_in)
		return -E2BIG;

	return 0;
}

static int compress_flush(struct compress *c,
			  struct drm_i915_error_object *dst)
{
	struct z_stream_s *zstream = &c->zstream;

	do {
		switch (zlib_deflate(zstream, Z_FINISH)) {
		case Z_OK: /* more space requested */
			zstream->next_out = compress_next_page(dst);
			if (IS_ERR(zstream->next_out))
				return PTR_ERR(zstream->next_out);

			zstream->avail_out = PAGE_SIZE;
			break;

		case Z_STREAM_END:
			goto end;

		default: /* any error */
			return -EIO;
		}
	} while (1);

end:
	memset(zstream->next_out, 0, zstream->avail_out);
	dst->unused = zstream->avail_out;
	return 0;
}

static void compress_fini(struct compress *c,
			  struct drm_i915_error_object *dst)
{
	struct z_stream_s *zstream = &c->zstream;

	zlib_deflateEnd(zstream);
	kfree(zstream->workspace);
	if (c->tmp)
		free_page((unsigned long)c->tmp);
}

static void err_compression_marker(struct drm_i915_error_state_buf *m)
{
	err_puts(m, ":");
}

#else

struct compress {
};

static bool compress_init(struct compress *c)
{
	return true;
}

static int compress_page(struct compress *c,
			 void *src,
			 struct drm_i915_error_object *dst)
{
	unsigned long page;
	void *ptr;

	page = __get_free_page(GFP_ATOMIC | __GFP_NOWARN);
	if (!page)
		return -ENOMEM;

	ptr = (void *)page;
	if (!i915_memcpy_from_wc(ptr, src, PAGE_SIZE))
		memcpy(ptr, src, PAGE_SIZE);
	dst->pages[dst->page_count++] = ptr;

	return 0;
}

static int compress_flush(struct compress *c,
			  struct drm_i915_error_object *dst)
{
	return 0;
}

static void compress_fini(struct compress *c,
			  struct drm_i915_error_object *dst)
{
}

static void err_compression_marker(struct drm_i915_error_state_buf *m)
{
	err_puts(m, "~");
}

#endif

static void print_error_buffers(struct drm_i915_error_state_buf *m,
				const char *name,
				struct drm_i915_error_buffer *err,
				int count)
{
	err_printf(m, "%s [%d]:\n", name, count);

	while (count--) {
		err_printf(m, "    %08x_%08x %8u %02x %02x",
			   upper_32_bits(err->gtt_offset),
			   lower_32_bits(err->gtt_offset),
			   err->size,
			   err->read_domains,
			   err->write_domain);
		err_puts(m, tiling_flag(err->tiling));
		err_puts(m, dirty_flag(err->dirty));
		err_puts(m, purgeable_flag(err->purgeable));
		err_puts(m, err->userptr ? " userptr" : "");
		err_puts(m, i915_cache_level_str(m->i915, err->cache_level));

		if (err->name)
			err_printf(m, " (name: %d)", err->name);
		if (err->fence_reg != I915_FENCE_REG_NONE)
			err_printf(m, " (fence: %d)", err->fence_reg);

		err_puts(m, "\n");
		err++;
	}
}

static void error_print_instdone(struct drm_i915_error_state_buf *m,
				 const struct drm_i915_error_engine *ee)
{
	int slice;
	int subslice;

	err_printf(m, "  INSTDONE: 0x%08x\n",
		   ee->instdone.instdone);

	if (ee->engine_id != RCS0 || INTEL_GEN(m->i915) <= 3)
		return;

	err_printf(m, "  SC_INSTDONE: 0x%08x\n",
		   ee->instdone.slice_common);

	if (INTEL_GEN(m->i915) <= 6)
		return;

	for_each_instdone_slice_subslice(m->i915, slice, subslice)
		err_printf(m, "  SAMPLER_INSTDONE[%d][%d]: 0x%08x\n",
			   slice, subslice,
			   ee->instdone.sampler[slice][subslice]);

	for_each_instdone_slice_subslice(m->i915, slice, subslice)
		err_printf(m, "  ROW_INSTDONE[%d][%d]: 0x%08x\n",
			   slice, subslice,
			   ee->instdone.row[slice][subslice]);
}

static void error_print_request(struct drm_i915_error_state_buf *m,
				const char *prefix,
				const struct drm_i915_error_request *erq,
				const unsigned long epoch)
{
	if (!erq->seqno)
		return;

	err_printf(m, "%s pid %d, seqno %8x:%08x%s%s, prio %d, emitted %dms, start %08x, head %08x, tail %08x\n",
		   prefix, erq->pid, erq->context, erq->seqno,
		   test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
			    &erq->flags) ? "!" : "",
		   test_bit(DMA_FENCE_FLAG_ENABLE_SIGNAL_BIT,
			    &erq->flags) ? "+" : "",
		   erq->sched_attr.priority,
		   jiffies_to_msecs(erq->jiffies - epoch),
		   erq->start, erq->head, erq->tail);
}

static void error_print_context(struct drm_i915_error_state_buf *m,
				const char *header,
				const struct drm_i915_error_context *ctx)
{
	err_printf(m, "%s%s[%d] hw_id %d, prio %d, guilty %d active %d\n",
		   header, ctx->comm, ctx->pid, ctx->hw_id,
		   ctx->sched_attr.priority, ctx->guilty, ctx->active);
}

static void error_print_engine(struct drm_i915_error_state_buf *m,
			       const struct drm_i915_error_engine *ee,
			       const unsigned long epoch)
{
	int n;

	err_printf(m, "%s command stream:\n",
		   engine_name(m->i915, ee->engine_id));
	err_printf(m, "  IDLE?: %s\n", yesno(ee->idle));
	err_printf(m, "  START: 0x%08x\n", ee->start);
	err_printf(m, "  HEAD:  0x%08x [0x%08x]\n", ee->head, ee->rq_head);
	err_printf(m, "  TAIL:  0x%08x [0x%08x, 0x%08x]\n",
		   ee->tail, ee->rq_post, ee->rq_tail);
	err_printf(m, "  CTL:   0x%08x\n", ee->ctl);
	err_printf(m, "  MODE:  0x%08x\n", ee->mode);
	err_printf(m, "  HWS:   0x%08x\n", ee->hws);
	err_printf(m, "  ACTHD: 0x%08x %08x\n",
		   (u32)(ee->acthd>>32), (u32)ee->acthd);
	err_printf(m, "  IPEIR: 0x%08x\n", ee->ipeir);
	err_printf(m, "  IPEHR: 0x%08x\n", ee->ipehr);

	error_print_instdone(m, ee);

	if (ee->batchbuffer) {
		u64 start = ee->batchbuffer->gtt_offset;
		u64 end = start + ee->batchbuffer->gtt_size;

		err_printf(m, "  batch: [0x%08x_%08x, 0x%08x_%08x]\n",
			   upper_32_bits(start), lower_32_bits(start),
			   upper_32_bits(end), lower_32_bits(end));
	}
	if (INTEL_GEN(m->i915) >= 4) {
		err_printf(m, "  BBADDR: 0x%08x_%08x\n",
			   (u32)(ee->bbaddr>>32), (u32)ee->bbaddr);
		err_printf(m, "  BB_STATE: 0x%08x\n", ee->bbstate);
		err_printf(m, "  INSTPS: 0x%08x\n", ee->instps);
	}
	err_printf(m, "  INSTPM: 0x%08x\n", ee->instpm);
	err_printf(m, "  FADDR: 0x%08x %08x\n", upper_32_bits(ee->faddr),
		   lower_32_bits(ee->faddr));
	if (INTEL_GEN(m->i915) >= 6) {
		err_printf(m, "  RC PSMI: 0x%08x\n", ee->rc_psmi);
		err_printf(m, "  FAULT_REG: 0x%08x\n", ee->fault_reg);
	}
	if (HAS_PPGTT(m->i915)) {
		err_printf(m, "  GFX_MODE: 0x%08x\n", ee->vm_info.gfx_mode);

		if (INTEL_GEN(m->i915) >= 8) {
			int i;
			for (i = 0; i < 4; i++)
				err_printf(m, "  PDP%d: 0x%016llx\n",
					   i, ee->vm_info.pdp[i]);
		} else {
			err_printf(m, "  PP_DIR_BASE: 0x%08x\n",
				   ee->vm_info.pp_dir_base);
		}
	}
	err_printf(m, "  ring->head: 0x%08x\n", ee->cpu_ring_head);
	err_printf(m, "  ring->tail: 0x%08x\n", ee->cpu_ring_tail);
	err_printf(m, "  hangcheck timestamp: %dms (%lu%s)\n",
		   jiffies_to_msecs(ee->hangcheck_timestamp - epoch),
		   ee->hangcheck_timestamp,
		   ee->hangcheck_timestamp == epoch ? "; epoch" : "");
	err_printf(m, "  engine reset count: %u\n", ee->reset_count);

	for (n = 0; n < ee->num_ports; n++) {
		err_printf(m, "  ELSP[%d]:", n);
		error_print_request(m, " ", &ee->execlist[n], epoch);
	}

	error_print_context(m, "  Active context: ", &ee->context);
}

void i915_error_printf(struct drm_i915_error_state_buf *e, const char *f, ...)
{
	va_list args;

	va_start(args, f);
	i915_error_vprintf(e, f, args);
	va_end(args);
}

static void print_error_obj(struct drm_i915_error_state_buf *m,
			    struct intel_engine_cs *engine,
			    const char *name,
			    struct drm_i915_error_object *obj)
{
	char out[ASCII85_BUFSZ];
	int page;

	if (!obj)
		return;

	if (name) {
		err_printf(m, "%s --- %s = 0x%08x %08x\n",
			   engine ? engine->name : "global", name,
			   upper_32_bits(obj->gtt_offset),
			   lower_32_bits(obj->gtt_offset));
	}

	err_compression_marker(m);
	for (page = 0; page < obj->page_count; page++) {
		int i, len;

		len = PAGE_SIZE;
		if (page == obj->page_count - 1)
			len -= obj->unused;
		len = ascii85_encode_len(len);

		for (i = 0; i < len; i++)
			err_puts(m, ascii85_encode(obj->pages[page][i], out));
	}
	err_puts(m, "\n");
}

static void err_print_capabilities(struct drm_i915_error_state_buf *m,
				   const struct intel_device_info *info,
				   const struct intel_runtime_info *runtime,
				   const struct intel_driver_caps *caps)
{
	struct drm_printer p = i915_error_printer(m);

	intel_device_info_dump_flags(info, &p);
	intel_driver_caps_print(caps, &p);
	intel_device_info_dump_topology(&runtime->sseu, &p);
}

static void err_print_params(struct drm_i915_error_state_buf *m,
			     const struct i915_params *params)
{
	struct drm_printer p = i915_error_printer(m);

	i915_params_dump(params, &p);
}

static void err_print_pciid(struct drm_i915_error_state_buf *m,
			    struct drm_i915_private *i915)
{
	struct pci_dev *pdev = i915->drm.pdev;

	err_printf(m, "PCI ID: 0x%04x\n", pdev->device);
	err_printf(m, "PCI Revision: 0x%02x\n", pdev->revision);
	err_printf(m, "PCI Subsystem: %04x:%04x\n",
		   pdev->subsystem_vendor,
		   pdev->subsystem_device);
}

static void err_print_uc(struct drm_i915_error_state_buf *m,
			 const struct i915_error_uc *error_uc)
{
	struct drm_printer p = i915_error_printer(m);
	const struct i915_gpu_state *error =
		container_of(error_uc, typeof(*error), uc);

	if (!error->device_info.has_guc)
		return;

	intel_uc_fw_dump(&error_uc->guc_fw, &p);
	intel_uc_fw_dump(&error_uc->huc_fw, &p);
	print_error_obj(m, NULL, "GuC log buffer", error_uc->guc_log);
}

static void err_free_sgl(struct scatterlist *sgl)
{
	while (sgl) {
		struct scatterlist *sg;

		for (sg = sgl; !sg_is_chain(sg); sg++) {
			kfree(sg_virt(sg));
			if (sg_is_last(sg))
				break;
		}

		sg = sg_is_last(sg) ? NULL : sg_chain_ptr(sg);
		free_page((unsigned long)sgl);
		sgl = sg;
	}
}

static void __err_print_to_sgl(struct drm_i915_error_state_buf *m,
			       struct i915_gpu_state *error)
{
	struct drm_i915_error_object *obj;
	struct timespec64 ts;
	int i, j;

	if (*error->error_msg)
		err_printf(m, "%s\n", error->error_msg);
	err_printf(m, "Kernel: %s %s\n",
		   init_utsname()->release,
		   init_utsname()->machine);
	ts = ktime_to_timespec64(error->time);
	err_printf(m, "Time: %lld s %ld us\n",
		   (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC);
	ts = ktime_to_timespec64(error->boottime);
	err_printf(m, "Boottime: %lld s %ld us\n",
		   (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC);
	ts = ktime_to_timespec64(error->uptime);
	err_printf(m, "Uptime: %lld s %ld us\n",
		   (s64)ts.tv_sec, ts.tv_nsec / NSEC_PER_USEC);
	err_printf(m, "Epoch: %lu jiffies (%u HZ)\n", error->epoch, HZ);
	err_printf(m, "Capture: %lu jiffies; %d ms ago, %d ms after epoch\n",
		   error->capture,
		   jiffies_to_msecs(jiffies - error->capture),
		   jiffies_to_msecs(error->capture - error->epoch));

	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
		if (!error->engine[i].context.pid)
			continue;

		err_printf(m, "Active process (on ring %s): %s [%d]\n",
			   engine_name(m->i915, i),
			   error->engine[i].context.comm,
			   error->engine[i].context.pid);
	}
	err_printf(m, "Reset count: %u\n", error->reset_count);
	err_printf(m, "Suspend count: %u\n", error->suspend_count);
	err_printf(m, "Platform: %s\n", intel_platform_name(error->device_info.platform));
	err_print_pciid(m, m->i915);

	err_printf(m, "IOMMU enabled?: %d\n", error->iommu);

	if (HAS_CSR(m->i915)) {
		struct intel_csr *csr = &m->i915->csr;

		err_printf(m, "DMC loaded: %s\n",
			   yesno(csr->dmc_payload != NULL));
		err_printf(m, "DMC fw version: %d.%d\n",
			   CSR_VERSION_MAJOR(csr->version),
			   CSR_VERSION_MINOR(csr->version));
	}

	err_printf(m, "GT awake: %s\n", yesno(error->awake));
	err_printf(m, "RPM wakelock: %s\n", yesno(error->wakelock));
	err_printf(m, "PM suspended: %s\n", yesno(error->suspended));
	err_printf(m, "EIR: 0x%08x\n", error->eir);
	err_printf(m, "IER: 0x%08x\n", error->ier);
	for (i = 0; i < error->ngtier; i++)
		err_printf(m, "GTIER[%d]: 0x%08x\n", i, error->gtier[i]);
	err_printf(m, "PGTBL_ER: 0x%08x\n", error->pgtbl_er);
	err_printf(m, "FORCEWAKE: 0x%08x\n", error->forcewake);
	err_printf(m, "DERRMR: 0x%08x\n", error->derrmr);
	err_printf(m, "CCID: 0x%08x\n", error->ccid);

	for (i = 0; i < error->nfence; i++)
		err_printf(m, "  fence[%d] = %08llx\n", i, error->fence[i]);

	if (INTEL_GEN(m->i915) >= 6) {
		err_printf(m, "ERROR: 0x%08x\n", error->error);

		if (INTEL_GEN(m->i915) >= 8)
			err_printf(m, "FAULT_TLB_DATA: 0x%08x 0x%08x\n",
				   error->fault_data1, error->fault_data0);

		err_printf(m, "DONE_REG: 0x%08x\n", error->done_reg);
	}

	if (IS_GEN(m->i915, 7))
		err_printf(m, "ERR_INT: 0x%08x\n", error->err_int);

	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
		if (error->engine[i].engine_id != -1)
			error_print_engine(m, &error->engine[i], error->epoch);
	}

	for (i = 0; i < ARRAY_SIZE(error->active_vm); i++) {
		char buf[128];
		int len, first = 1;

		if (!error->active_vm[i])
			break;

		len = scnprintf(buf, sizeof(buf), "Active (");
		for (j = 0; j < ARRAY_SIZE(error->engine); j++) {
			if (error->engine[j].vm != error->active_vm[i])
				continue;

			len += scnprintf(buf + len, sizeof(buf), "%s%s",
					 first ? "" : ", ",
					 m->i915->engine[j]->name);
			first = 0;
		}
		scnprintf(buf + len, sizeof(buf), ")");
		print_error_buffers(m, buf,
				    error->active_bo[i],
				    error->active_bo_count[i]);
	}

	print_error_buffers(m, "Pinned (global)",
			    error->pinned_bo,
			    error->pinned_bo_count);

	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
		const struct drm_i915_error_engine *ee = &error->engine[i];

		obj = ee->batchbuffer;
		if (obj) {
			err_puts(m, m->i915->engine[i]->name);
			if (ee->context.pid)
				err_printf(m, " (submitted by %s [%d])",
					   ee->context.comm,
					   ee->context.pid);
			err_printf(m, " --- gtt_offset = 0x%08x %08x\n",
				   upper_32_bits(obj->gtt_offset),
				   lower_32_bits(obj->gtt_offset));
			print_error_obj(m, m->i915->engine[i], NULL, obj);
		}

		for (j = 0; j < ee->user_bo_count; j++)
			print_error_obj(m, m->i915->engine[i],
					"user", ee->user_bo[j]);

		if (ee->num_requests) {
			err_printf(m, "%s --- %d requests\n",
				   m->i915->engine[i]->name,
				   ee->num_requests);
			for (j = 0; j < ee->num_requests; j++)
				error_print_request(m, " ",
						    &ee->requests[j],
						    error->epoch);
		}

		print_error_obj(m, m->i915->engine[i],
				"ringbuffer", ee->ringbuffer);

		print_error_obj(m, m->i915->engine[i],
				"HW Status", ee->hws_page);

		print_error_obj(m, m->i915->engine[i],
				"HW context", ee->ctx);

		print_error_obj(m, m->i915->engine[i],
				"WA context", ee->wa_ctx);

		print_error_obj(m, m->i915->engine[i],
				"WA batchbuffer", ee->wa_batchbuffer);

		print_error_obj(m, m->i915->engine[i],
				"NULL context", ee->default_state);
	}

	if (error->overlay)
		intel_overlay_print_error_state(m, error->overlay);

	if (error->display)
		intel_display_print_error_state(m, error->display);

	err_print_capabilities(m, &error->device_info, &error->runtime_info,
			       &error->driver_caps);
	err_print_params(m, &error->params);
	err_print_uc(m, &error->uc);
}

static int err_print_to_sgl(struct i915_gpu_state *error)
{
	struct drm_i915_error_state_buf m;

	if (IS_ERR(error))
		return PTR_ERR(error);

	if (READ_ONCE(error->sgl))
		return 0;

	memset(&m, 0, sizeof(m));
	m.i915 = error->i915;

	__err_print_to_sgl(&m, error);

	if (m.buf) {
		__sg_set_buf(m.cur++, m.buf, m.bytes, m.iter);
		m.bytes = 0;
		m.buf = NULL;
	}
	if (m.cur) {
		GEM_BUG_ON(m.end < m.cur);
		sg_mark_end(m.cur - 1);
	}
	GEM_BUG_ON(m.sgl && !m.cur);

	if (m.err) {
		err_free_sgl(m.sgl);
		return m.err;
	}

	if (cmpxchg(&error->sgl, NULL, m.sgl))
		err_free_sgl(m.sgl);

	return 0;
}

ssize_t i915_gpu_state_copy_to_buffer(struct i915_gpu_state *error,
				      char *buf, loff_t off, size_t rem)
{
	struct scatterlist *sg;
	size_t count;
	loff_t pos;
	int err;

	if (!error || !rem)
		return 0;

	err = err_print_to_sgl(error);
	if (err)
		return err;

	sg = READ_ONCE(error->fit);
	if (!sg || off < sg->dma_address)
		sg = error->sgl;
	if (!sg)
		return 0;

	pos = sg->dma_address;
	count = 0;
	do {
		size_t len, start;

		if (sg_is_chain(sg)) {
			sg = sg_chain_ptr(sg);
			GEM_BUG_ON(sg_is_chain(sg));
		}

		len = sg->length;
		if (pos + len <= off) {
			pos += len;
			continue;
		}

		start = sg->offset;
		if (pos < off) {
			GEM_BUG_ON(off - pos > len);
			len -= off - pos;
			start += off - pos;
			pos = off;
		}

		len = min(len, rem);
		GEM_BUG_ON(!len || len > sg->length);

		memcpy(buf, page_address(sg_page(sg)) + start, len);

		count += len;
		pos += len;

		buf += len;
		rem -= len;
		if (!rem) {
			WRITE_ONCE(error->fit, sg);
			break;
		}
	} while (!sg_is_last(sg++));

	return count;
}

static void i915_error_object_free(struct drm_i915_error_object *obj)
{
	int page;

	if (obj == NULL)
		return;

	for (page = 0; page < obj->page_count; page++)
		free_page((unsigned long)obj->pages[page]);

	kfree(obj);
}


static void cleanup_params(struct i915_gpu_state *error)
{
	i915_params_free(&error->params);
}

static void cleanup_uc_state(struct i915_gpu_state *error)
{
	struct i915_error_uc *error_uc = &error->uc;

	kfree(error_uc->guc_fw.path);
	kfree(error_uc->huc_fw.path);
	i915_error_object_free(error_uc->guc_log);
}

void __i915_gpu_state_free(struct kref *error_ref)
{
	struct i915_gpu_state *error =
		container_of(error_ref, typeof(*error), ref);
	long i, j;

	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
		struct drm_i915_error_engine *ee = &error->engine[i];

		for (j = 0; j < ee->user_bo_count; j++)
			i915_error_object_free(ee->user_bo[j]);
		kfree(ee->user_bo);

		i915_error_object_free(ee->batchbuffer);
		i915_error_object_free(ee->wa_batchbuffer);
		i915_error_object_free(ee->ringbuffer);
		i915_error_object_free(ee->hws_page);
		i915_error_object_free(ee->ctx);
		i915_error_object_free(ee->wa_ctx);

		kfree(ee->requests);
	}

	for (i = 0; i < ARRAY_SIZE(error->active_bo); i++)
		kfree(error->active_bo[i]);
	kfree(error->pinned_bo);

	kfree(error->overlay);
	kfree(error->display);

	cleanup_params(error);
	cleanup_uc_state(error);

	err_free_sgl(error->sgl);
	kfree(error);
}

static struct drm_i915_error_object *
i915_error_object_create(struct drm_i915_private *i915,
			 struct i915_vma *vma)
{
	struct i915_ggtt *ggtt = &i915->ggtt;
	const u64 slot = ggtt->error_capture.start;
	struct drm_i915_error_object *dst;
	struct compress compress;
	unsigned long num_pages;
	struct sgt_iter iter;
	dma_addr_t dma;
	int ret;

	if (!vma || !vma->pages)
		return NULL;

	num_pages = min_t(u64, vma->size, vma->obj->base.size) >> PAGE_SHIFT;
	num_pages = DIV_ROUND_UP(10 * num_pages, 8); /* worstcase zlib growth */
	dst = kmalloc(sizeof(*dst) + num_pages * sizeof(u32 *),
		      GFP_ATOMIC | __GFP_NOWARN);
	if (!dst)
		return NULL;

	dst->gtt_offset = vma->node.start;
	dst->gtt_size = vma->node.size;
	dst->num_pages = num_pages;
	dst->page_count = 0;
	dst->unused = 0;

	if (!compress_init(&compress)) {
		kfree(dst);
		return NULL;
	}

	ret = -EINVAL;
	for_each_sgt_dma(dma, iter, vma->pages) {
		void __iomem *s;

		ggtt->vm.insert_page(&ggtt->vm, dma, slot, I915_CACHE_NONE, 0);

		s = io_mapping_map_atomic_wc(&ggtt->iomap, slot);
		ret = compress_page(&compress, (void  __force *)s, dst);
		io_mapping_unmap_atomic(s);
		if (ret)
			break;
	}

	if (ret || compress_flush(&compress, dst)) {
		while (dst->page_count--)
			free_page((unsigned long)dst->pages[dst->page_count]);
		kfree(dst);
		dst = NULL;
	}

	compress_fini(&compress, dst);
	return dst;
}

static void capture_bo(struct drm_i915_error_buffer *err,
		       struct i915_vma *vma)
{
	struct drm_i915_gem_object *obj = vma->obj;

	err->size = obj->base.size;
	err->name = obj->base.name;

	err->gtt_offset = vma->node.start;
	err->read_domains = obj->read_domains;
	err->write_domain = obj->write_domain;
	err->fence_reg = vma->fence ? vma->fence->id : -1;
	err->tiling = i915_gem_object_get_tiling(obj);
	err->dirty = obj->mm.dirty;
	err->purgeable = obj->mm.madv != I915_MADV_WILLNEED;
	err->userptr = obj->userptr.mm != NULL;
	err->cache_level = obj->cache_level;
}

static u32 capture_error_bo(struct drm_i915_error_buffer *err,
			    int count, struct list_head *head,
			    unsigned int flags)
#define ACTIVE_ONLY BIT(0)
#define PINNED_ONLY BIT(1)
{
	struct i915_vma *vma;
	int i = 0;

	list_for_each_entry(vma, head, vm_link) {
		if (!vma->obj)
			continue;

		if (flags & ACTIVE_ONLY && !i915_vma_is_active(vma))
			continue;

		if (flags & PINNED_ONLY && !i915_vma_is_pinned(vma))
			continue;

		capture_bo(err++, vma);
		if (++i == count)
			break;
	}

	return i;
}

/*
 * Generate a semi-unique error code. The code is not meant to have meaning, The
 * code's only purpose is to try to prevent false duplicated bug reports by
 * grossly estimating a GPU error state.
 *
 * TODO Ideally, hashing the batchbuffer would be a very nice way to determine
 * the hang if we could strip the GTT offset information from it.
 *
 * It's only a small step better than a random number in its current form.
 */
static u32 i915_error_generate_code(struct i915_gpu_state *error,
				    unsigned long engine_mask)
{
	/*
	 * IPEHR would be an ideal way to detect errors, as it's the gross
	 * measure of "the command that hung." However, has some very common
	 * synchronization commands which almost always appear in the case
	 * strictly a client bug. Use instdone to differentiate those some.
	 */
	if (engine_mask) {
		struct drm_i915_error_engine *ee =
			&error->engine[ffs(engine_mask)];

		return ee->ipehr ^ ee->instdone.instdone;
	}

	return 0;
}

static void gem_record_fences(struct i915_gpu_state *error)
{
	struct drm_i915_private *dev_priv = error->i915;
	int i;

	if (INTEL_GEN(dev_priv) >= 6) {
		for (i = 0; i < dev_priv->num_fence_regs; i++)
			error->fence[i] = I915_READ64(FENCE_REG_GEN6_LO(i));
	} else if (INTEL_GEN(dev_priv) >= 4) {
		for (i = 0; i < dev_priv->num_fence_regs; i++)
			error->fence[i] = I915_READ64(FENCE_REG_965_LO(i));
	} else {
		for (i = 0; i < dev_priv->num_fence_regs; i++)
			error->fence[i] = I915_READ(FENCE_REG(i));
	}
	error->nfence = i;
}

static void error_record_engine_registers(struct i915_gpu_state *error,
					  struct intel_engine_cs *engine,
					  struct drm_i915_error_engine *ee)
{
	struct drm_i915_private *dev_priv = engine->i915;

	if (INTEL_GEN(dev_priv) >= 6) {
		ee->rc_psmi = I915_READ(RING_PSMI_CTL(engine->mmio_base));
		if (INTEL_GEN(dev_priv) >= 8)
			ee->fault_reg = I915_READ(GEN8_RING_FAULT_REG);
		else
			ee->fault_reg = I915_READ(RING_FAULT_REG(engine));
	}

	if (INTEL_GEN(dev_priv) >= 4) {
		ee->faddr = I915_READ(RING_DMA_FADD(engine->mmio_base));
		ee->ipeir = I915_READ(RING_IPEIR(engine->mmio_base));
		ee->ipehr = I915_READ(RING_IPEHR(engine->mmio_base));
		ee->instps = I915_READ(RING_INSTPS(engine->mmio_base));
		ee->bbaddr = I915_READ(RING_BBADDR(engine->mmio_base));
		if (INTEL_GEN(dev_priv) >= 8) {
			ee->faddr |= (u64) I915_READ(RING_DMA_FADD_UDW(engine->mmio_base)) << 32;
			ee->bbaddr |= (u64) I915_READ(RING_BBADDR_UDW(engine->mmio_base)) << 32;
		}
		ee->bbstate = I915_READ(RING_BBSTATE(engine->mmio_base));
	} else {
		ee->faddr = I915_READ(DMA_FADD_I8XX);
		ee->ipeir = I915_READ(IPEIR);
		ee->ipehr = I915_READ(IPEHR);
	}

	intel_engine_get_instdone(engine, &ee->instdone);

	ee->instpm = I915_READ(RING_INSTPM(engine->mmio_base));
	ee->acthd = intel_engine_get_active_head(engine);
	ee->start = I915_READ_START(engine);
	ee->head = I915_READ_HEAD(engine);
	ee->tail = I915_READ_TAIL(engine);
	ee->ctl = I915_READ_CTL(engine);
	if (INTEL_GEN(dev_priv) > 2)
		ee->mode = I915_READ_MODE(engine);

	if (!HWS_NEEDS_PHYSICAL(dev_priv)) {
		i915_reg_t mmio;

		if (IS_GEN(dev_priv, 7)) {
			switch (engine->id) {
			default:
				MISSING_CASE(engine->id);
			case RCS0:
				mmio = RENDER_HWS_PGA_GEN7;
				break;
			case BCS0:
				mmio = BLT_HWS_PGA_GEN7;
				break;
			case VCS0:
				mmio = BSD_HWS_PGA_GEN7;
				break;
			case VECS0:
				mmio = VEBOX_HWS_PGA_GEN7;
				break;
			}
		} else if (IS_GEN(engine->i915, 6)) {
			mmio = RING_HWS_PGA_GEN6(engine->mmio_base);
		} else {
			/* XXX: gen8 returns to sanity */
			mmio = RING_HWS_PGA(engine->mmio_base);
		}

		ee->hws = I915_READ(mmio);
	}

	ee->idle = intel_engine_is_idle(engine);
	if (!ee->idle)
		ee->hangcheck_timestamp = engine->hangcheck.action_timestamp;
	ee->reset_count = i915_reset_engine_count(&dev_priv->gpu_error,
						  engine);

	if (HAS_PPGTT(dev_priv)) {
		int i;

		ee->vm_info.gfx_mode = I915_READ(RING_MODE_GEN7(engine));

		if (IS_GEN(dev_priv, 6))
			ee->vm_info.pp_dir_base =
				I915_READ(RING_PP_DIR_BASE_READ(engine));
		else if (IS_GEN(dev_priv, 7))
			ee->vm_info.pp_dir_base =
				I915_READ(RING_PP_DIR_BASE(engine));
		else if (INTEL_GEN(dev_priv) >= 8)
			for (i = 0; i < 4; i++) {
				ee->vm_info.pdp[i] =
					I915_READ(GEN8_RING_PDP_UDW(engine, i));
				ee->vm_info.pdp[i] <<= 32;
				ee->vm_info.pdp[i] |=
					I915_READ(GEN8_RING_PDP_LDW(engine, i));
			}
	}
}

static void record_request(struct i915_request *request,
			   struct drm_i915_error_request *erq)
{
	struct i915_gem_context *ctx = request->gem_context;

	erq->flags = request->fence.flags;
	erq->context = request->fence.context;
	erq->seqno = request->fence.seqno;
	erq->sched_attr = request->sched.attr;
	erq->jiffies = request->emitted_jiffies;
	erq->start = i915_ggtt_offset(request->ring->vma);
	erq->head = request->head;
	erq->tail = request->tail;

	rcu_read_lock();
	erq->pid = ctx->pid ? pid_nr(ctx->pid) : 0;
	rcu_read_unlock();
}

static void engine_record_requests(struct intel_engine_cs *engine,
				   struct i915_request *first,
				   struct drm_i915_error_engine *ee)
{
	struct i915_request *request;
	int count;

	count = 0;
	request = first;
	list_for_each_entry_from(request, &engine->timeline.requests, link)
		count++;
	if (!count)
		return;

	ee->requests = kcalloc(count, sizeof(*ee->requests), GFP_ATOMIC);
	if (!ee->requests)
		return;

	ee->num_requests = count;

	count = 0;
	request = first;
	list_for_each_entry_from(request, &engine->timeline.requests, link) {
		if (count >= ee->num_requests) {
			/*
			 * If the ring request list was changed in
			 * between the point where the error request
			 * list was created and dimensioned and this
			 * point then just exit early to avoid crashes.
			 *
			 * We don't need to communicate that the
			 * request list changed state during error
			 * state capture and that the error state is
			 * slightly incorrect as a consequence since we
			 * are typically only interested in the request
			 * list state at the point of error state
			 * capture, not in any changes happening during
			 * the capture.
			 */
			break;
		}

		record_request(request, &ee->requests[count++]);
	}
	ee->num_requests = count;
}

static void error_record_engine_execlists(struct intel_engine_cs *engine,
					  struct drm_i915_error_engine *ee)
{
	const struct intel_engine_execlists * const execlists = &engine->execlists;
	unsigned int n;

	for (n = 0; n < execlists_num_ports(execlists); n++) {
		struct i915_request *rq = port_request(&execlists->port[n]);

		if (!rq)
			break;

		record_request(rq, &ee->execlist[n]);
	}

	ee->num_ports = n;
}

static void record_context(struct drm_i915_error_context *e,
			   struct i915_gem_context *ctx)
{
	if (ctx->pid) {
		struct task_struct *task;

		rcu_read_lock();
		task = pid_task(ctx->pid, PIDTYPE_PID);
		if (task) {
			strcpy(e->comm, task->comm);
			e->pid = task->pid;
		}
		rcu_read_unlock();
	}

	e->hw_id = ctx->hw_id;
	e->sched_attr = ctx->sched;
	e->guilty = atomic_read(&ctx->guilty_count);
	e->active = atomic_read(&ctx->active_count);
}

static void request_record_user_bo(struct i915_request *request,
				   struct drm_i915_error_engine *ee)
{
	struct i915_capture_list *c;
	struct drm_i915_error_object **bo;
	long count, max;

	max = 0;
	for (c = request->capture_list; c; c = c->next)
		max++;
	if (!max)
		return;

	bo = kmalloc_array(max, sizeof(*bo), GFP_ATOMIC);
	if (!bo) {
		/* If we can't capture everything, try to capture something. */
		max = min_t(long, max, PAGE_SIZE / sizeof(*bo));
		bo = kmalloc_array(max, sizeof(*bo), GFP_ATOMIC);
	}
	if (!bo)
		return;

	count = 0;
	for (c = request->capture_list; c; c = c->next) {
		bo[count] = i915_error_object_create(request->i915, c->vma);
		if (!bo[count])
			break;
		if (++count == max)
			break;
	}

	ee->user_bo = bo;
	ee->user_bo_count = count;
}

static struct drm_i915_error_object *
capture_object(struct drm_i915_private *dev_priv,
	       struct drm_i915_gem_object *obj)
{
	if (obj && i915_gem_object_has_pages(obj)) {
		struct i915_vma fake = {
			.node = { .start = U64_MAX, .size = obj->base.size },
			.size = obj->base.size,
			.pages = obj->mm.pages,
			.obj = obj,
		};

		return i915_error_object_create(dev_priv, &fake);
	} else {
		return NULL;
	}
}

static void gem_record_rings(struct i915_gpu_state *error)
{
	struct drm_i915_private *i915 = error->i915;
	struct i915_ggtt *ggtt = &i915->ggtt;
	int i;

	for (i = 0; i < I915_NUM_ENGINES; i++) {
		struct intel_engine_cs *engine = i915->engine[i];
		struct drm_i915_error_engine *ee = &error->engine[i];
		struct i915_request *request;

		ee->engine_id = -1;

		if (!engine)
			continue;

		ee->engine_id = i;

		error_record_engine_registers(error, engine, ee);
		error_record_engine_execlists(engine, ee);

		request = intel_engine_find_active_request(engine);
		if (request) {
			struct i915_gem_context *ctx = request->gem_context;
			struct intel_ring *ring;

			ee->vm = ctx->ppgtt ? &ctx->ppgtt->vm : &ggtt->vm;

			record_context(&ee->context, ctx);

			/* We need to copy these to an anonymous buffer
			 * as the simplest method to avoid being overwritten
			 * by userspace.
			 */
			ee->batchbuffer =
				i915_error_object_create(i915, request->batch);

			if (HAS_BROKEN_CS_TLB(i915))
				ee->wa_batchbuffer =
					i915_error_object_create(i915,
								 i915->gt.scratch);
			request_record_user_bo(request, ee);

			ee->ctx =
				i915_error_object_create(i915,
							 request->hw_context->state);

			error->simulated |=
				i915_gem_context_no_error_capture(ctx);

			ee->rq_head = request->head;
			ee->rq_post = request->postfix;
			ee->rq_tail = request->tail;

			ring = request->ring;
			ee->cpu_ring_head = ring->head;
			ee->cpu_ring_tail = ring->tail;
			ee->ringbuffer =
				i915_error_object_create(i915, ring->vma);

			engine_record_requests(engine, request, ee);
		}

		ee->hws_page =
			i915_error_object_create(i915,
						 engine->status_page.vma);

		ee->wa_ctx = i915_error_object_create(i915, engine->wa_ctx.vma);

		ee->default_state = capture_object(i915, engine->default_state);
	}
}

static void gem_capture_vm(struct i915_gpu_state *error,
			   struct i915_address_space *vm,
			   int idx)
{
	struct drm_i915_error_buffer *active_bo;
	struct i915_vma *vma;
	int count;

	count = 0;
	list_for_each_entry(vma, &vm->bound_list, vm_link)
		if (i915_vma_is_active(vma))
			count++;

	active_bo = NULL;
	if (count)
		active_bo = kcalloc(count, sizeof(*active_bo), GFP_ATOMIC);
	if (active_bo)
		count = capture_error_bo(active_bo,
					 count, &vm->bound_list,
					 ACTIVE_ONLY);
	else
		count = 0;

	error->active_vm[idx] = vm;
	error->active_bo[idx] = active_bo;
	error->active_bo_count[idx] = count;
}

static void capture_active_buffers(struct i915_gpu_state *error)
{
	int cnt = 0, i, j;

	BUILD_BUG_ON(ARRAY_SIZE(error->engine) > ARRAY_SIZE(error->active_bo));
	BUILD_BUG_ON(ARRAY_SIZE(error->active_bo) != ARRAY_SIZE(error->active_vm));
	BUILD_BUG_ON(ARRAY_SIZE(error->active_bo) != ARRAY_SIZE(error->active_bo_count));

	/* Scan each engine looking for unique active contexts/vm */
	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
		struct drm_i915_error_engine *ee = &error->engine[i];
		bool found;

		if (!ee->vm)
			continue;

		found = false;
		for (j = 0; j < i && !found; j++)
			found = error->engine[j].vm == ee->vm;
		if (!found)
			gem_capture_vm(error, ee->vm, cnt++);
	}
}

static void capture_pinned_buffers(struct i915_gpu_state *error)
{
	struct i915_address_space *vm = &error->i915->ggtt.vm;
	struct drm_i915_error_buffer *bo;
	struct i915_vma *vma;
	int count;

	count = 0;
	list_for_each_entry(vma, &vm->bound_list, vm_link)
		count++;

	bo = NULL;
	if (count)
		bo = kcalloc(count, sizeof(*bo), GFP_ATOMIC);
	if (!bo)
		return;

	error->pinned_bo_count =
		capture_error_bo(bo, count, &vm->bound_list, PINNED_ONLY);
	error->pinned_bo = bo;
}

static void capture_uc_state(struct i915_gpu_state *error)
{
	struct drm_i915_private *i915 = error->i915;
	struct i915_error_uc *error_uc = &error->uc;

	/* Capturing uC state won't be useful if there is no GuC */
	if (!error->device_info.has_guc)
		return;

	error_uc->guc_fw = i915->guc.fw;
	error_uc->huc_fw = i915->huc.fw;

	/* Non-default firmware paths will be specified by the modparam.
	 * As modparams are generally accesible from the userspace make
	 * explicit copies of the firmware paths.
	 */
	error_uc->guc_fw.path = kstrdup(i915->guc.fw.path, GFP_ATOMIC);
	error_uc->huc_fw.path = kstrdup(i915->huc.fw.path, GFP_ATOMIC);
	error_uc->guc_log = i915_error_object_create(i915, i915->guc.log.vma);
}

/* Capture all registers which don't fit into another category. */
static void capture_reg_state(struct i915_gpu_state *error)
{
	struct drm_i915_private *dev_priv = error->i915;
	int i;

	/* General organization
	 * 1. Registers specific to a single generation
	 * 2. Registers which belong to multiple generations
	 * 3. Feature specific registers.
	 * 4. Everything else
	 * Please try to follow the order.
	 */

	/* 1: Registers specific to a single generation */
	if (IS_VALLEYVIEW(dev_priv)) {
		error->gtier[0] = I915_READ(GTIER);
		error->ier = I915_READ(VLV_IER);
		error->forcewake = I915_READ_FW(FORCEWAKE_VLV);
	}

	if (IS_GEN(dev_priv, 7))
		error->err_int = I915_READ(GEN7_ERR_INT);

	if (INTEL_GEN(dev_priv) >= 8) {
		error->fault_data0 = I915_READ(GEN8_FAULT_TLB_DATA0);
		error->fault_data1 = I915_READ(GEN8_FAULT_TLB_DATA1);
	}

	if (IS_GEN(dev_priv, 6)) {
		error->forcewake = I915_READ_FW(FORCEWAKE);
		error->gab_ctl = I915_READ(GAB_CTL);
		error->gfx_mode = I915_READ(GFX_MODE);
	}

	/* 2: Registers which belong to multiple generations */
	if (INTEL_GEN(dev_priv) >= 7)
		error->forcewake = I915_READ_FW(FORCEWAKE_MT);

	if (INTEL_GEN(dev_priv) >= 6) {
		error->derrmr = I915_READ(DERRMR);
		error->error = I915_READ(ERROR_GEN6);
		error->done_reg = I915_READ(DONE_REG);
	}

	if (INTEL_GEN(dev_priv) >= 5)
		error->ccid = I915_READ(CCID);

	/* 3: Feature specific registers */
	if (IS_GEN_RANGE(dev_priv, 6, 7)) {
		error->gam_ecochk = I915_READ(GAM_ECOCHK);
		error->gac_eco = I915_READ(GAC_ECO_BITS);
	}

	/* 4: Everything else */
	if (INTEL_GEN(dev_priv) >= 11) {
		error->ier = I915_READ(GEN8_DE_MISC_IER);
		error->gtier[0] = I915_READ(GEN11_RENDER_COPY_INTR_ENABLE);
		error->gtier[1] = I915_READ(GEN11_VCS_VECS_INTR_ENABLE);
		error->gtier[2] = I915_READ(GEN11_GUC_SG_INTR_ENABLE);
		error->gtier[3] = I915_READ(GEN11_GPM_WGBOXPERF_INTR_ENABLE);
		error->gtier[4] = I915_READ(GEN11_CRYPTO_RSVD_INTR_ENABLE);
		error->gtier[5] = I915_READ(GEN11_GUNIT_CSME_INTR_ENABLE);
		error->ngtier = 6;
	} else if (INTEL_GEN(dev_priv) >= 8) {
		error->ier = I915_READ(GEN8_DE_MISC_IER);
		for (i = 0; i < 4; i++)
			error->gtier[i] = I915_READ(GEN8_GT_IER(i));
		error->ngtier = 4;
	} else if (HAS_PCH_SPLIT(dev_priv)) {
		error->ier = I915_READ(DEIER);
		error->gtier[0] = I915_READ(GTIER);
		error->ngtier = 1;
	} else if (IS_GEN(dev_priv, 2)) {
		error->ier = I915_READ16(IER);
	} else if (!IS_VALLEYVIEW(dev_priv)) {
		error->ier = I915_READ(IER);
	}
	error->eir = I915_READ(EIR);
	error->pgtbl_er = I915_READ(PGTBL_ER);
}

static const char *
error_msg(struct i915_gpu_state *error, unsigned long engines, const char *msg)
{
	int len;
	int i;

	for (i = 0; i < ARRAY_SIZE(error->engine); i++)
		if (!error->engine[i].context.pid)
			engines &= ~BIT(i);

	len = scnprintf(error->error_msg, sizeof(error->error_msg),
			"GPU HANG: ecode %d:%lx:0x%08x",
			INTEL_GEN(error->i915), engines,
			i915_error_generate_code(error, engines));
	if (engines) {
		/* Just show the first executing process, more is confusing */
		i = __ffs(engines);
		len += scnprintf(error->error_msg + len,
				 sizeof(error->error_msg) - len,
				 ", in %s [%d]",
				 error->engine[i].context.comm,
				 error->engine[i].context.pid);
	}
	if (msg)
		len += scnprintf(error->error_msg + len,
				 sizeof(error->error_msg) - len,
				 ", %s", msg);

	return error->error_msg;
}

static void capture_gen_state(struct i915_gpu_state *error)
{
	struct drm_i915_private *i915 = error->i915;

	error->awake = i915->gt.awake;
	error->wakelock = atomic_read(&i915->runtime_pm.wakeref_count);
	error->suspended = i915->runtime_pm.suspended;

	error->iommu = -1;
#ifdef CONFIG_INTEL_IOMMU
	error->iommu = intel_iommu_gfx_mapped;
#endif
	error->reset_count = i915_reset_count(&i915->gpu_error);
	error->suspend_count = i915->suspend_count;

	memcpy(&error->device_info,
	       INTEL_INFO(i915),
	       sizeof(error->device_info));
	memcpy(&error->runtime_info,
	       RUNTIME_INFO(i915),
	       sizeof(error->runtime_info));
	error->driver_caps = i915->caps;
}

static void capture_params(struct i915_gpu_state *error)
{
	i915_params_copy(&error->params, &i915_modparams);
}

static unsigned long capture_find_epoch(const struct i915_gpu_state *error)
{
	unsigned long epoch = error->capture;
	int i;

	for (i = 0; i < ARRAY_SIZE(error->engine); i++) {
		const struct drm_i915_error_engine *ee = &error->engine[i];

		if (ee->hangcheck_timestamp &&
		    time_before(ee->hangcheck_timestamp, epoch))
			epoch = ee->hangcheck_timestamp;
	}

	return epoch;
}

static void capture_finish(struct i915_gpu_state *error)
{
	struct i915_ggtt *ggtt = &error->i915->ggtt;
	const u64 slot = ggtt->error_capture.start;

	ggtt->vm.clear_range(&ggtt->vm, slot, PAGE_SIZE);
}

static int capture(void *data)
{
	struct i915_gpu_state *error = data;

	error->time = ktime_get_real();
	error->boottime = ktime_get_boottime();
	error->uptime = ktime_sub(ktime_get(),
				  error->i915->gt.last_init_time);
	error->capture = jiffies;

	capture_params(error);
	capture_gen_state(error);
	capture_uc_state(error);
	capture_reg_state(error);
	gem_record_fences(error);
	gem_record_rings(error);
	capture_active_buffers(error);
	capture_pinned_buffers(error);

	error->overlay = intel_overlay_capture_error_state(error->i915);
	error->display = intel_display_capture_error_state(error->i915);

	error->epoch = capture_find_epoch(error);

	capture_finish(error);
	return 0;
}

#define DAY_AS_SECONDS(x) (24 * 60 * 60 * (x))

struct i915_gpu_state *
i915_capture_gpu_state(struct drm_i915_private *i915)
{
	struct i915_gpu_state *error;

	/* Check if GPU capture has been disabled */
	error = READ_ONCE(i915->gpu_error.first_error);
	if (IS_ERR(error))
		return error;

	error = kzalloc(sizeof(*error), GFP_ATOMIC);
	if (!error) {
		i915_disable_error_state(i915, -ENOMEM);
		return ERR_PTR(-ENOMEM);
	}

	kref_init(&error->ref);
	error->i915 = i915;

	stop_machine(capture, error, NULL);

	return error;
}

/**
 * i915_capture_error_state - capture an error record for later analysis
 * @i915: i915 device
 * @engine_mask: the mask of engines triggering the hang
 * @msg: a message to insert into the error capture header
 *
 * Should be called when an error is detected (either a hang or an error
 * interrupt) to capture error state from the time of the error.  Fills
 * out a structure which becomes available in debugfs for user level tools
 * to pick up.
 */
void i915_capture_error_state(struct drm_i915_private *i915,
			      unsigned long engine_mask,
			      const char *msg)
{
	static bool warned;
	struct i915_gpu_state *error;
	unsigned long flags;

	if (!i915_modparams.error_capture)
		return;

	if (READ_ONCE(i915->gpu_error.first_error))
		return;

	error = i915_capture_gpu_state(i915);
	if (IS_ERR(error))
		return;

	dev_info(i915->drm.dev, "%s\n", error_msg(error, engine_mask, msg));

	if (!error->simulated) {
		spin_lock_irqsave(&i915->gpu_error.lock, flags);
		if (!i915->gpu_error.first_error) {
			i915->gpu_error.first_error = error;
			error = NULL;
		}
		spin_unlock_irqrestore(&i915->gpu_error.lock, flags);
	}

	if (error) {
		__i915_gpu_state_free(&error->ref);
		return;
	}

	if (!warned &&
	    ktime_get_real_seconds() - DRIVER_TIMESTAMP < DAY_AS_SECONDS(180)) {
		DRM_INFO("GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.\n");
		DRM_INFO("Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel\n");
		DRM_INFO("drm/i915 developers can then reassign to the right component if it's not a kernel issue.\n");
		DRM_INFO("The gpu crash dump is required to analyze gpu hangs, so please always attach it.\n");
		DRM_INFO("GPU crash dump saved to /sys/class/drm/card%d/error\n",
			 i915->drm.primary->index);
		warned = true;
	}
}

struct i915_gpu_state *
i915_first_error_state(struct drm_i915_private *i915)
{
	struct i915_gpu_state *error;

	spin_lock_irq(&i915->gpu_error.lock);
	error = i915->gpu_error.first_error;
	if (!IS_ERR_OR_NULL(error))
		i915_gpu_state_get(error);
	spin_unlock_irq(&i915->gpu_error.lock);

	return error;
}

void i915_reset_error_state(struct drm_i915_private *i915)
{
	struct i915_gpu_state *error;

	spin_lock_irq(&i915->gpu_error.lock);
	error = i915->gpu_error.first_error;
	if (error != ERR_PTR(-ENODEV)) /* if disabled, always disabled */
		i915->gpu_error.first_error = NULL;
	spin_unlock_irq(&i915->gpu_error.lock);

	if (!IS_ERR_OR_NULL(error))
		i915_gpu_state_put(error);
}

void i915_disable_error_state(struct drm_i915_private *i915, int err)
{
	spin_lock_irq(&i915->gpu_error.lock);
	if (!i915->gpu_error.first_error)
		i915->gpu_error.first_error = ERR_PTR(err);
	spin_unlock_irq(&i915->gpu_error.lock);
}