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From:   Chris Wilson <chris@chris-wilson.co.uk>
To:     intel-gfx@lists.freedesktop.org
Cc:     dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        Chris Wilson <chris@chris-wilson.co.uk>,
        Steven Rostedt <rostedt@goodmis.org>
Subject: [PATCH 2/2] RFC drm/i915: Export per-client debug tracing
Date:   Sun,  1 Mar 2020 15:52:48 +0000
Message-Id: <20200301155248.4132645-2-chris@chris-wilson.co.uk>
In-Reply-To: <20200301155248.4132645-1-chris@chris-wilson.co.uk>
References: <20200301155248.4132645-1-chris@chris-wilson.co.uk>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Rather than put sensitive, and often voluminous, user details into a
global dmesg, report the error and debug messages directly back to the
user via the kernel tracing mechanism.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c   | 104 ++++++++++-----
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    | 124 ++++++++++--------
 drivers/gpu/drm/i915/gem/i915_gem_pages.c     |   6 +-
 drivers/gpu/drm/i915/i915_drv.h               |   4 +
 drivers/gpu/drm/i915/i915_gem.c               |   5 +-
 include/uapi/drm/i915_drm.h                   |   7 +
 6 files changed, 156 insertions(+), 94 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index e525ead073f7..c136a8c90e27 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -81,6 +81,8 @@
 
 #define ALL_L3_SLICES(dev) (1 << NUM_L3_SLICES(dev)) - 1
 
+#define CTX_TRACE(ctx, ...) TRACE((ctx)->file_priv->trace, __VA_ARGS__)
+
 static struct i915_global_gem_context {
 	struct i915_global base;
 	struct kmem_cache *slab_luts;
@@ -158,8 +160,12 @@ lookup_user_engine(struct i915_gem_context *ctx,
 		engine = intel_engine_lookup_user(ctx->i915,
 						  ci->engine_class,
 						  ci->engine_instance);
-		if (!engine)
+		if (!engine) {
+			CTX_TRACE(ctx,
+				  "Unknown engine {class:%d, instance:%d}\n",
+				  ci->engine_class, ci->engine_instance);
 			return ERR_PTR(-EINVAL);
+		}
 
 		idx = engine->legacy_idx;
 	} else {
@@ -762,8 +768,6 @@ i915_gem_create_context(struct drm_i915_private *i915, unsigned int flags)
 
 		ppgtt = i915_ppgtt_create(&i915->gt);
 		if (IS_ERR(ppgtt)) {
-			drm_dbg(&i915->drm, "PPGTT setup failed (%ld)\n",
-				PTR_ERR(ppgtt));
 			context_close(ctx);
 			return ERR_CAST(ppgtt);
 		}
@@ -1461,14 +1465,15 @@ set_engines__load_balance(struct i915_user_extension __user *base, void *data)
 		return -EFAULT;
 
 	if (idx >= set->engines->num_engines) {
-		drm_dbg(&i915->drm, "Invalid placement value, %d >= %d\n",
-			idx, set->engines->num_engines);
+		CTX_TRACE(set->ctx,
+			  "Invalid placement value, %d >= %d\n",
+			  idx, set->engines->num_engines);
 		return -EINVAL;
 	}
 
 	idx = array_index_nospec(idx, set->engines->num_engines);
 	if (set->engines->engines[idx]) {
-		drm_dbg(&i915->drm,
+		CTX_TRACE(set->ctx,
 			"Invalid placement[%d], already occupied\n", idx);
 		return -EEXIST;
 	}
@@ -1505,9 +1510,9 @@ set_engines__load_balance(struct i915_user_extension __user *base, void *data)
 						       ci.engine_class,
 						       ci.engine_instance);
 		if (!siblings[n]) {
-			drm_dbg(&i915->drm,
-				"Invalid sibling[%d]: { class:%d, inst:%d }\n",
-				n, ci.engine_class, ci.engine_instance);
+			CTX_TRACE(set->ctx,
+				  "Invalid sibling[%d]: { class:%d, inst:%d }\n",
+				  n, ci.engine_class, ci.engine_instance);
 			err = -EINVAL;
 			goto out_siblings;
 		}
@@ -1551,15 +1556,15 @@ set_engines__bond(struct i915_user_extension __user *base, void *data)
 		return -EFAULT;
 
 	if (idx >= set->engines->num_engines) {
-		drm_dbg(&i915->drm,
-			"Invalid index for virtual engine: %d >= %d\n",
-			idx, set->engines->num_engines);
+		CTX_TRACE(set->ctx,
+			  "Invalid index for virtual engine: %d >= %d\n",
+			  idx, set->engines->num_engines);
 		return -EINVAL;
 	}
 
 	idx = array_index_nospec(idx, set->engines->num_engines);
 	if (!set->engines->engines[idx]) {
-		drm_dbg(&i915->drm, "Invalid engine at %d\n", idx);
+		CTX_TRACE(set->ctx, "Invalid engine at %d\n", idx);
 		return -EINVAL;
 	}
 	virtual = set->engines->engines[idx]->engine;
@@ -1580,9 +1585,9 @@ set_engines__bond(struct i915_user_extension __user *base, void *data)
 	master = intel_engine_lookup_user(i915,
 					  ci.engine_class, ci.engine_instance);
 	if (!master) {
-		drm_dbg(&i915->drm,
-			"Unrecognised master engine: { class:%u, instance:%u }\n",
-			ci.engine_class, ci.engine_instance);
+		CTX_TRACE(set->ctx,
+			  "Unrecognised master engine: { class:%u, instance:%u }\n",
+			  ci.engine_class, ci.engine_instance);
 		return -EINVAL;
 	}
 
@@ -1599,9 +1604,9 @@ set_engines__bond(struct i915_user_extension __user *base, void *data)
 						ci.engine_class,
 						ci.engine_instance);
 		if (!bond) {
-			drm_dbg(&i915->drm,
-				"Unrecognised engine[%d] for bonding: { class:%d, instance: %d }\n",
-				n, ci.engine_class, ci.engine_instance);
+			CTX_TRACE(set->ctx,
+				  "Unrecognised engine[%d] for bonding: { class:%d, instance: %d }\n",
+				  n, ci.engine_class, ci.engine_instance);
 			return -EINVAL;
 		}
 
@@ -1701,7 +1706,6 @@ static int
 set_engines(struct i915_gem_context *ctx,
 	    const struct drm_i915_gem_context_param *args)
 {
-	struct drm_i915_private *i915 = ctx->i915;
 	struct i915_context_param_engines __user *user =
 		u64_to_user_ptr(args->value);
 	struct set_engines set = { .ctx = ctx };
@@ -1723,8 +1727,9 @@ set_engines(struct i915_gem_context *ctx,
 	BUILD_BUG_ON(!IS_ALIGNED(sizeof(*user), sizeof(*user->engines)));
 	if (args->size < sizeof(*user) ||
 	    !IS_ALIGNED(args->size, sizeof(*user->engines))) {
-		drm_dbg(&i915->drm, "Invalid size for engine array: %d\n",
-			args->size);
+		CTX_TRACE(ctx,
+			  "Invalid size for engine array: %d\n",
+			  args->size);
 		return -EINVAL;
 	}
 
@@ -1761,9 +1766,9 @@ set_engines(struct i915_gem_context *ctx,
 						  ci.engine_class,
 						  ci.engine_instance);
 		if (!engine) {
-			drm_dbg(&i915->drm,
-				"Invalid engine[%d]: { class:%d, instance:%d }\n",
-				n, ci.engine_class, ci.engine_instance);
+			CTX_TRACE(ctx,
+				  "Invalid engine[%d]: { class:%d, instance:%d }\n",
+				  n, ci.engine_class, ci.engine_instance);
 			__free_engines(set.engines, n);
 			return -ENOENT;
 		}
@@ -1906,6 +1911,36 @@ get_engines(struct i915_gem_context *ctx,
 	return err;
 }
 
+static int
+get_trace(struct i915_gem_context *ctx,
+	  struct drm_i915_gem_context_param *args)
+{
+	int fd;
+
+	if (args->ctx_id) /* single trace per-fd, let's not mix it up! */
+		return -EINVAL;
+
+	if (!READ_ONCE(ctx->file_priv->trace)) {
+		struct trace_array *tr;
+
+		tr = trace_array_create();
+		if (IS_ERR(tr))
+			return PTR_ERR(tr);
+
+		if (cmpxchg(&ctx->file_priv->trace, NULL, tr))
+			trace_array_destroy(tr);
+	}
+
+	fd = anon_trace_getfd("i915-client", ctx->file_priv->trace);
+	if (fd < 0)
+		return fd;
+
+	args->size = 0;
+	args->value = fd;
+
+	return 0;
+}
+
 static int
 set_persistence(struct i915_gem_context *ctx,
 		const struct drm_i915_gem_context_param *args)
@@ -1943,8 +1978,13 @@ static int set_priority(struct i915_gem_context *ctx,
 		return -ENODEV;
 
 	if (priority > I915_CONTEXT_MAX_USER_PRIORITY ||
-	    priority < I915_CONTEXT_MIN_USER_PRIORITY)
+	    priority < I915_CONTEXT_MIN_USER_PRIORITY) {
+		CTX_TRACE(ctx, "priority %d out-of-range [%d, %d]\n",
+			  priority,
+			  I915_CONTEXT_MAX_USER_PRIORITY,
+			  I915_CONTEXT_MIN_USER_PRIORITY);
 		return -EINVAL;
+	}
 
 	if (priority > I915_CONTEXT_DEFAULT_PRIORITY &&
 	    !capable(CAP_SYS_NICE))
@@ -2302,9 +2342,9 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 
 	ext_data.fpriv = file->driver_priv;
 	if (client_is_banned(ext_data.fpriv)) {
-		drm_dbg(&i915->drm,
-			"client %s[%d] banned from creating ctx\n",
-			current->comm, task_pid_nr(current));
+		TRACE(ext_data.fpriv->trace,
+		      "client %s[%d] banned from creating ctx\n",
+		      current->comm, task_pid_nr(current));
 		return -EIO;
 	}
 
@@ -2326,7 +2366,7 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 		goto err_ctx;
 
 	args->ctx_id = id;
-	drm_dbg(&i915->drm, "HW context %d created\n", args->ctx_id);
+	TRACE(ext_data.fpriv->trace, "HW context %d created\n", args->ctx_id);
 
 	return 0;
 
@@ -2480,6 +2520,10 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
 		ret = get_ringsize(ctx, args);
 		break;
 
+	case I915_CONTEXT_PARAM_TRACE:
+		ret = get_trace(ctx, args);
+		break;
+
 	case I915_CONTEXT_PARAM_BAN_PERIOD:
 	default:
 		ret = -EINVAL;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index ac0e5fc5675e..620a0e8da5d8 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -275,6 +275,16 @@ struct i915_execbuffer {
 	struct hlist_head *buckets; /** ht for relocation handles */
 };
 
+static inline struct trace_array *file_trace(struct drm_file *f)
+{
+	struct drm_i915_file_private *fp = f->driver_priv;
+
+	return fp->trace;
+}
+
+#define FILE_TRACE(F, ...) TRACE(file_trace(F), __VA_ARGS__)
+#define EB_TRACE(E, ...) FILE_TRACE((E)->file, __VA_ARGS__)
+
 #define exec_entry(EB, VMA) (&(EB)->exec[(VMA)->exec_flags - (EB)->flags])
 
 static inline bool eb_use_cmdparser(const struct i915_execbuffer *eb)
@@ -419,7 +429,6 @@ eb_validate_vma(struct i915_execbuffer *eb,
 		struct drm_i915_gem_exec_object2 *entry,
 		struct i915_vma *vma)
 {
-	struct drm_i915_private *i915 = eb->i915;
 	if (unlikely(entry->flags & eb->invalid_flags))
 		return -EINVAL;
 
@@ -443,9 +452,9 @@ eb_validate_vma(struct i915_execbuffer *eb,
 	}
 
 	if (unlikely(vma->exec_flags)) {
-		drm_dbg(&i915->drm,
-			"Object [handle %d, index %d] appears more than once in object list\n",
-			entry->handle, (int)(entry - eb->exec));
+		EB_TRACE(eb,
+			 "Object [handle %d, index %d] appears more than once in object list\n",
+			 entry->handle, (int)(entry - eb->exec));
 		return -EINVAL;
 	}
 
@@ -1331,7 +1340,6 @@ eb_relocate_entry(struct i915_execbuffer *eb,
 		  struct i915_vma *vma,
 		  const struct drm_i915_gem_relocation_entry *reloc)
 {
-	struct drm_i915_private *i915 = eb->i915;
 	struct i915_vma *target;
 	int err;
 
@@ -1342,24 +1350,26 @@ eb_relocate_entry(struct i915_execbuffer *eb,
 
 	/* Validate that the target is in a valid r/w GPU domain */
 	if (unlikely(reloc->write_domain & (reloc->write_domain - 1))) {
-		drm_dbg(&i915->drm, "reloc with multiple write domains: "
-			  "target %d offset %d "
-			  "read %08x write %08x",
-			  reloc->target_handle,
-			  (int) reloc->offset,
-			  reloc->read_domains,
-			  reloc->write_domain);
+		EB_TRACE(eb,
+			 "reloc with multiple write domains: "
+			 "target %d offset %d "
+			 "read %08x write %08x",
+			 reloc->target_handle,
+			 (int) reloc->offset,
+			 reloc->read_domains,
+			 reloc->write_domain);
 		return -EINVAL;
 	}
 	if (unlikely((reloc->write_domain | reloc->read_domains)
 		     & ~I915_GEM_GPU_DOMAINS)) {
-		drm_dbg(&i915->drm, "reloc with read/write non-GPU domains: "
-			  "target %d offset %d "
-			  "read %08x write %08x",
-			  reloc->target_handle,
-			  (int) reloc->offset,
-			  reloc->read_domains,
-			  reloc->write_domain);
+		EB_TRACE(eb,
+			 "reloc with read/write non-GPU domains: "
+			 "target %d offset %d "
+			 "read %08x write %08x",
+			 reloc->target_handle,
+			 (int) reloc->offset,
+			 reloc->read_domains,
+			 reloc->write_domain);
 		return -EINVAL;
 	}
 
@@ -1393,18 +1403,20 @@ eb_relocate_entry(struct i915_execbuffer *eb,
 	/* Check that the relocation address is valid... */
 	if (unlikely(reloc->offset >
 		     vma->size - (eb->reloc_cache.use_64bit_reloc ? 8 : 4))) {
-		drm_dbg(&i915->drm, "Relocation beyond object bounds: "
-			  "target %d offset %d size %d.\n",
-			  reloc->target_handle,
-			  (int)reloc->offset,
-			  (int)vma->size);
+		EB_TRACE(eb,
+			 "Relocation beyond object bounds: "
+			 "target %d offset %d size %d.\n",
+			 reloc->target_handle,
+			 (int)reloc->offset,
+			 (int)vma->size);
 		return -EINVAL;
 	}
 	if (unlikely(reloc->offset & 3)) {
-		drm_dbg(&i915->drm, "Relocation not 4-byte aligned: "
-			  "target %d offset %d.\n",
-			  reloc->target_handle,
-			  (int)reloc->offset);
+		EB_TRACE(eb,
+			 "Relocation not 4-byte aligned: "
+			 "target %d offset %d.\n",
+			 reloc->target_handle,
+			 (int)reloc->offset);
 		return -EINVAL;
 	}
 
@@ -1914,13 +1926,14 @@ static int i915_gem_check_execbuffer(struct drm_i915_gem_execbuffer2 *exec)
 	return 0;
 }
 
-static int i915_reset_gen7_sol_offsets(struct i915_request *rq)
+static int gen7_sol_reset(struct i915_execbuffer *eb)
 {
+	struct i915_request *rq = eb->request;
 	u32 *cs;
 	int i;
 
 	if (!IS_GEN(rq->i915, 7) || rq->engine->id != RCS0) {
-		drm_dbg(&rq->i915->drm, "sol reset is gen7/rcs only\n");
+		EB_TRACE(eb, "sol reset is gen7/rcs only\n");
 		return -EINVAL;
 	}
 
@@ -2074,7 +2087,6 @@ static int eb_parse_pipeline(struct i915_execbuffer *eb,
 
 static int eb_parse(struct i915_execbuffer *eb)
 {
-	struct drm_i915_private *i915 = eb->i915;
 	struct intel_engine_pool_node *pool;
 	struct i915_vma *shadow, *trampoline;
 	unsigned int len;
@@ -2090,8 +2102,7 @@ static int eb_parse(struct i915_execbuffer *eb)
 		 * post-scan tampering
 		 */
 		if (!eb->context->vm->has_read_only) {
-			drm_dbg(&i915->drm,
-				"Cannot prevent post-scan tampering without RO capable vm\n");
+			EB_TRACE(eb, "Cannot prevent post-scan tampering without RO capable vm\n");
 			return -EINVAL;
 		}
 	} else {
@@ -2173,7 +2184,7 @@ static int eb_submit(struct i915_execbuffer *eb)
 		return err;
 
 	if (eb->args->flags & I915_EXEC_GEN7_SOL_RESET) {
-		err = i915_reset_gen7_sol_offsets(eb->request);
+		err = gen7_sol_reset(eb);
 		if (err)
 			return err;
 	}
@@ -2379,9 +2390,9 @@ eb_select_legacy_ring(struct i915_execbuffer *eb,
 
 	if (user_ring_id != I915_EXEC_BSD &&
 	    (args->flags & I915_EXEC_BSD_MASK)) {
-		drm_dbg(&i915->drm,
-			"execbuf with non bsd ring but with invalid "
-			"bsd dispatch flags: %d\n", (int)(args->flags));
+		EB_TRACE(eb,
+			 "execbuf with non bsd ring but with invalid "
+			 "bsd dispatch flags: %d\n", (int)(args->flags));
 		return -1;
 	}
 
@@ -2395,9 +2406,9 @@ eb_select_legacy_ring(struct i915_execbuffer *eb,
 			bsd_idx >>= I915_EXEC_BSD_SHIFT;
 			bsd_idx--;
 		} else {
-			drm_dbg(&i915->drm,
-				"execbuf with unknown bsd ring: %u\n",
-				bsd_idx);
+			EB_TRACE(eb,
+				 "execbuf with unknown bsd ring: %u\n",
+				 bsd_idx);
 			return -1;
 		}
 
@@ -2405,8 +2416,8 @@ eb_select_legacy_ring(struct i915_execbuffer *eb,
 	}
 
 	if (user_ring_id >= ARRAY_SIZE(user_ring_map)) {
-		drm_dbg(&i915->drm, "execbuf with unknown ring: %u\n",
-			user_ring_id);
+		EB_TRACE(eb, "execbuf with unknown ring: %u\n",
+			 user_ring_id);
 		return -1;
 	}
 
@@ -2680,14 +2691,14 @@ i915_gem_do_execbuffer(struct drm_device *dev,
 	}
 
 	if (unlikely(*eb.batch->exec_flags & EXEC_OBJECT_WRITE)) {
-		drm_dbg(&i915->drm,
-			"Attempting to use self-modifying batch buffer\n");
+		EB_TRACE(&eb,
+			 "Attempting to use self-modifying batch buffer\n");
 		err = -EINVAL;
 		goto err_vma;
 	}
 	if (eb.batch_start_offset > eb.batch->size ||
 	    eb.batch_len > eb.batch->size - eb.batch_start_offset) {
-		drm_dbg(&i915->drm, "Attempting to use out-of-bounds batch\n");
+		EB_TRACE(&eb, "Attempting to use out-of-bounds batch\n");
 		err = -EINVAL;
 		goto err_vma;
 	}
@@ -2851,7 +2862,6 @@ int
 i915_gem_execbuffer_ioctl(struct drm_device *dev, void *data,
 			  struct drm_file *file)
 {
-	struct drm_i915_private *i915 = to_i915(dev);
 	struct drm_i915_gem_execbuffer *args = data;
 	struct drm_i915_gem_execbuffer2 exec2;
 	struct drm_i915_gem_exec_object *exec_list = NULL;
@@ -2861,7 +2871,7 @@ i915_gem_execbuffer_ioctl(struct drm_device *dev, void *data,
 	int err;
 
 	if (!check_buffer_count(count)) {
-		drm_dbg(&i915->drm, "execbuf2 with %zd buffers\n", count);
+		FILE_TRACE(file, "execbuf2 with %zd buffers\n", count);
 		return -EINVAL;
 	}
 
@@ -2886,9 +2896,9 @@ i915_gem_execbuffer_ioctl(struct drm_device *dev, void *data,
 	exec2_list = kvmalloc_array(count + 1, eb_element_size(),
 				    __GFP_NOWARN | GFP_KERNEL);
 	if (exec_list == NULL || exec2_list == NULL) {
-		drm_dbg(&i915->drm,
-			"Failed to allocate exec list for %d buffers\n",
-			args->buffer_count);
+		FILE_TRACE(file,
+			   "Failed to allocate exec list for %d buffers\n",
+			   args->buffer_count);
 		kvfree(exec_list);
 		kvfree(exec2_list);
 		return -ENOMEM;
@@ -2897,8 +2907,8 @@ i915_gem_execbuffer_ioctl(struct drm_device *dev, void *data,
 			     u64_to_user_ptr(args->buffers_ptr),
 			     sizeof(*exec_list) * count);
 	if (err) {
-		drm_dbg(&i915->drm, "copy %d exec entries failed %d\n",
-			args->buffer_count, err);
+		FILE_TRACE(file, "copy %d exec entries failed %d\n",
+			   args->buffer_count, err);
 		kvfree(exec_list);
 		kvfree(exec2_list);
 		return -EFAULT;
@@ -2945,7 +2955,6 @@ int
 i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
 			   struct drm_file *file)
 {
-	struct drm_i915_private *i915 = to_i915(dev);
 	struct drm_i915_gem_execbuffer2 *args = data;
 	struct drm_i915_gem_exec_object2 *exec2_list;
 	struct drm_syncobj **fences = NULL;
@@ -2953,7 +2962,7 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
 	int err;
 
 	if (!check_buffer_count(count)) {
-		drm_dbg(&i915->drm, "execbuf2 with %zd buffers\n", count);
+		FILE_TRACE(file, "execbuf2 with %zd buffers\n", count);
 		return -EINVAL;
 	}
 
@@ -2965,14 +2974,15 @@ i915_gem_execbuffer2_ioctl(struct drm_device *dev, void *data,
 	exec2_list = kvmalloc_array(count + 1, eb_element_size(),
 				    __GFP_NOWARN | GFP_KERNEL);
 	if (exec2_list == NULL) {
-		drm_dbg(&i915->drm, "Failed to allocate exec list for %zd buffers\n",
-			count);
+		FILE_TRACE(file,
+			   "Failed to allocate exec list for %zd buffers\n",
+			   count);
 		return -ENOMEM;
 	}
 	if (copy_from_user(exec2_list,
 			   u64_to_user_ptr(args->buffers_ptr),
 			   sizeof(*exec2_list) * count)) {
-		drm_dbg(&i915->drm, "copy %zd exec entries failed\n", count);
+		FILE_TRACE(file, "copy %zd exec entries failed\n", count);
 		kvfree(exec2_list);
 		return -EFAULT;
 	}
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index 24f4cadea114..001ad1c02249 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -83,14 +83,10 @@ void __i915_gem_object_set_pages(struct drm_i915_gem_object *obj,
 
 int ____i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
 {
-	struct drm_i915_private *i915 = to_i915(obj->base.dev);
 	int err;
 
-	if (unlikely(obj->mm.madv != I915_MADV_WILLNEED)) {
-		drm_dbg(&i915->drm,
-			"Attempting to obtain a purgeable object\n");
+	if (unlikely(obj->mm.madv != I915_MADV_WILLNEED))
 		return -EFAULT;
-	}
 
 	err = obj->ops->get_pages(obj);
 	GEM_BUG_ON(!err && !i915_gem_object_has_pages(obj));
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index b621df933212..dccb71735d5d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -46,6 +46,7 @@
 #include <linux/dma-resv.h>
 #include <linux/shmem_fs.h>
 #include <linux/stackdepot.h>
+#include <linux/trace.h>
 #include <linux/xarray.h>
 
 #include <drm/intel-gtt.h>
@@ -223,7 +224,10 @@ struct drm_i915_file_private {
 	/** ban_score: Accumulated score of all ctx bans and fast hangs. */
 	atomic_t ban_score;
 	unsigned long hang_timestamp;
+
+	struct trace_array *trace;
 };
+#define TRACE(tr, ...) trace_array_printk((tr), _THIS_IP_,  __VA_ARGS__)
 
 /* Interface history:
  *
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index ca5420012a22..baea6be98b0f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1286,6 +1286,9 @@ void i915_gem_release(struct drm_device *dev, struct drm_file *file)
 	struct drm_i915_file_private *file_priv = file->driver_priv;
 	struct i915_request *request;
 
+	if (file_priv->trace)
+		trace_array_destroy(file_priv->trace);
+
 	/* Clean up our request list when the client is going away, so that
 	 * later retire_requests won't dereference our soon-to-be-gone
 	 * file_priv.
@@ -1301,8 +1304,6 @@ int i915_gem_open(struct drm_i915_private *i915, struct drm_file *file)
 	struct drm_i915_file_private *file_priv;
 	int ret;
 
-	DRM_DEBUG("\n");
-
 	file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL);
 	if (!file_priv)
 		return -ENOMEM;
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index 2813e579b480..c69827e04b48 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1640,6 +1640,13 @@ struct drm_i915_gem_context_param {
  * Default is 16 KiB.
  */
 #define I915_CONTEXT_PARAM_RINGSIZE	0xc
+
+/*
+ * I915_CONTEXT_PARAM_TRACE:
+ *
+ * Return an fd representing a pipe of all trace output from this file.
+ */
+#define I915_CONTEXT_PARAM_TRACE	0xd
 /* Must be kept compact -- no holes and well documented */
 
 	__u64 value;
-- 
2.25.1