drm/i915: Record batch buffer following GPU error

In order to improve our diagnostic capabilities following a GPU hang
and subsequent reset, we need to record the batch buffer that triggered
the error. We assume that the current batch buffer, plus a few details
about what else is on the active list, will be sufficient -- at the very
least an improvement over nothing.

The extra information is stored in /debug/dri/.../i915_error_state
following an error, and may be decoded using
intel_gpu_tools/tools/intel_error_decode.

v2: Avoid excessive work under spinlocks.
v3: Include ringbuffer for later analysis.
v4: Use kunmap correctly and record more buffer state.
v5: Search ringbuffer for current batch buffer
v6: Use a work fn for the impossible IRQ error case.
v7: Avoid non-atomic paths whilst in IRQ context.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 217 insertions, 7 deletions

diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
index 1a56ae7b5a78..ba1d8314c1ce 100644
--- a/drivers/gpu/drm/i915/i915_irq.c
+++ b/drivers/gpu/drm/i915/i915_irq.c
@@ -432,6 +432,121 @@ static void i915_error_work_func(struct work_struct *work)
         }
 }
 
+static struct drm_i915_error_object *
+i915_error_object_create(struct drm_device *dev,
+                         struct drm_gem_object *src)
+{
+        struct drm_i915_error_object *dst;
+        struct drm_i915_gem_object *src_priv;
+        int page, page_count;
+
+        if (src == NULL)
+                return NULL;
+
+        src_priv = src->driver_private;
+        if (src_priv->pages == NULL)
+                return NULL;
+
+        page_count = src->size / PAGE_SIZE;
+
+        dst = kmalloc(sizeof(*dst) + page_count * sizeof (u32 *), GFP_ATOMIC);
+        if (dst == NULL)
+                return NULL;
+
+        for (page = 0; page < page_count; page++) {
+                void *s, *d = kmalloc(PAGE_SIZE, GFP_ATOMIC);
+                if (d == NULL)
+                        goto unwind;
+                s = kmap_atomic(src_priv->pages[page], KM_USER0);
+                memcpy(d, s, PAGE_SIZE);
+                kunmap_atomic(s, KM_USER0);
+                dst->pages[page] = d;
+        }
+        dst->page_count = page_count;
+        dst->gtt_offset = src_priv->gtt_offset;
+
+        return dst;
+
+unwind:
+        while (page--)
+                kfree(dst->pages[page]);
+        kfree(dst);
+        return NULL;
+}
+
+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++)
+                kfree(obj->pages[page]);
+
+        kfree(obj);
+}
+
+static void
+i915_error_state_free(struct drm_device *dev,
+                      struct drm_i915_error_state *error)
+{
+        i915_error_object_free(error->batchbuffer[0]);
+        i915_error_object_free(error->batchbuffer[1]);
+        i915_error_object_free(error->ringbuffer);
+        kfree(error->active_bo);
+        kfree(error);
+}
+
+static u32
+i915_get_bbaddr(struct drm_device *dev, u32 *ring)
+{
+        u32 cmd;
+
+        if (IS_I830(dev) || IS_845G(dev))
+                cmd = MI_BATCH_BUFFER;
+        else if (IS_I965G(dev))
+                cmd = (MI_BATCH_BUFFER_START | (2 << 6) |
+                       MI_BATCH_NON_SECURE_I965);
+        else
+                cmd = (MI_BATCH_BUFFER_START | (2 << 6));
+
+        return ring[0] == cmd ? ring[1] : 0;
+}
+
+static u32
+i915_ringbuffer_last_batch(struct drm_device *dev)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        u32 head, bbaddr;
+        u32 *ring;
+
+        /* Locate the current position in the ringbuffer and walk back
+         * to find the most recently dispatched batch buffer.
+         */
+        bbaddr = 0;
+        head = I915_READ(PRB0_HEAD) & HEAD_ADDR;
+        ring = (u32 *)(dev_priv->ring.virtual_start + head);
+
+        while (--ring >= (u32 *)dev_priv->ring.virtual_start) {
+                bbaddr = i915_get_bbaddr(dev, ring);
+                if (bbaddr)
+                        break;
+        }
+
+        if (bbaddr == 0) {
+                ring = (u32 *)(dev_priv->ring.virtual_start + dev_priv->ring.Size);
+                while (--ring >= (u32 *)dev_priv->ring.virtual_start) {
+                        bbaddr = i915_get_bbaddr(dev, ring);
+                        if (bbaddr)
+                                break;
+                }
+        }
+
+        return bbaddr;
+}
+
 /**
  * i915_capture_error_state - capture an error record for later analysis
  * @dev: drm device
@@ -444,19 +559,26 @@ static void i915_error_work_func(struct work_struct *work)
 static void i915_capture_error_state(struct drm_device *dev)
 {
         struct drm_i915_private *dev_priv = dev->dev_private;
+        struct drm_i915_gem_object *obj_priv;
         struct drm_i915_error_state *error;
+        struct drm_gem_object *batchbuffer[2];
         unsigned long flags;
+        u32 bbaddr;
+        int count;
 
         spin_lock_irqsave(&dev_priv->error_lock, flags);
-        if (dev_priv->first_error)
-                goto out;
+        error = dev_priv->first_error;
+        spin_unlock_irqrestore(&dev_priv->error_lock, flags);
+        if (error)
+                return;
 
         error = kmalloc(sizeof(*error), GFP_ATOMIC);
         if (!error) {
-                DRM_DEBUG_DRIVER("out ot memory, not capturing error state\n");
-                goto out;
+                DRM_DEBUG_DRIVER("out of memory, not capturing error state\n");
+                return;
         }
 
+        error->seqno = i915_get_gem_seqno(dev);
         error->eir = I915_READ(EIR);
         error->pgtbl_er = I915_READ(PGTBL_ER);
         error->pipeastat = I915_READ(PIPEASTAT);
@@ -467,6 +589,7 @@ static void i915_capture_error_state(struct drm_device *dev)
                 error->ipehr = I915_READ(IPEHR);
                 error->instdone = I915_READ(INSTDONE);
                 error->acthd = I915_READ(ACTHD);
+                error->bbaddr = 0;
         } else {
                 error->ipeir = I915_READ(IPEIR_I965);
                 error->ipehr = I915_READ(IPEHR_I965);
@@ -474,14 +597,101 @@ static void i915_capture_error_state(struct drm_device *dev)
                 error->instps = I915_READ(INSTPS);
                 error->instdone1 = I915_READ(INSTDONE1);
                 error->acthd = I915_READ(ACTHD_I965);
+                error->bbaddr = I915_READ64(BB_ADDR);
         }
 
-        do_gettimeofday(&error->time);
+        bbaddr = i915_ringbuffer_last_batch(dev);
+
+        /* Grab the current batchbuffer, most likely to have crashed. */
+        batchbuffer[0] = NULL;
+        batchbuffer[1] = NULL;
+        count = 0;
+        list_for_each_entry(obj_priv, &dev_priv->mm.active_list, list) {
+                struct drm_gem_object *obj = obj_priv->obj;
+
+                if (batchbuffer[0] == NULL &&
+                    bbaddr >= obj_priv->gtt_offset &&
+                    bbaddr < obj_priv->gtt_offset + obj->size)
+                        batchbuffer[0] = obj;
+
+                if (batchbuffer[1] == NULL &&
+                    error->acthd >= obj_priv->gtt_offset &&
+                    error->acthd < obj_priv->gtt_offset + obj->size &&
+                    batchbuffer[0] != obj)
+                        batchbuffer[1] = obj;
+
+                count++;
+        }
 
-        dev_priv->first_error = error;
+        /* We need to copy these to an anonymous buffer as the simplest
+         * method to avoid being overwritten by userpace.
+         */
+        error->batchbuffer[0] = i915_error_object_create(dev, batchbuffer[0]);
+        error->batchbuffer[1] = i915_error_object_create(dev, batchbuffer[1]);
+
+        /* Record the ringbuffer */
+        error->ringbuffer = i915_error_object_create(dev, dev_priv->ring.ring_obj);
+
+        /* Record buffers on the active list. */
+        error->active_bo = NULL;
+        error->active_bo_count = 0;
+
+        if (count)
+                error->active_bo = kmalloc(sizeof(*error->active_bo)*count,
+                                           GFP_ATOMIC);
+
+        if (error->active_bo) {
+                int i = 0;
+                list_for_each_entry(obj_priv, &dev_priv->mm.active_list, list) {
+                        struct drm_gem_object *obj = obj_priv->obj;
+
+                        error->active_bo[i].size = obj->size;
+                        error->active_bo[i].name = obj->name;
+                        error->active_bo[i].seqno = obj_priv->last_rendering_seqno;
+                        error->active_bo[i].gtt_offset = obj_priv->gtt_offset;
+                        error->active_bo[i].read_domains = obj->read_domains;
+                        error->active_bo[i].write_domain = obj->write_domain;
+                        error->active_bo[i].fence_reg = obj_priv->fence_reg;
+                        error->active_bo[i].pinned = 0;
+                        if (obj_priv->pin_count > 0)
+                                error->active_bo[i].pinned = 1;
+                        if (obj_priv->user_pin_count > 0)
+                                error->active_bo[i].pinned = -1;
+                        error->active_bo[i].tiling = obj_priv->tiling_mode;
+                        error->active_bo[i].dirty = obj_priv->dirty;
+                        error->active_bo[i].purgeable = obj_priv->madv != I915_MADV_WILLNEED;
+
+                        if (++i == count)
+                                break;
+                }
+                error->active_bo_count = i;
+        }
+
+        do_gettimeofday(&error->time);
 
-out:
+        spin_lock_irqsave(&dev_priv->error_lock, flags);
+        if (dev_priv->first_error == NULL) {
+                dev_priv->first_error = error;
+                error = NULL;
+        }
         spin_unlock_irqrestore(&dev_priv->error_lock, flags);
+
+        if (error)
+                i915_error_state_free(dev, error);
+}
+
+void i915_destroy_error_state(struct drm_device *dev)
+{
+        struct drm_i915_private *dev_priv = dev->dev_private;
+        struct drm_i915_error_state *error;
+
+        spin_lock(&dev_priv->error_lock);
+        error = dev_priv->first_error;
+        dev_priv->first_error = NULL;
+        spin_unlock(&dev_priv->error_lock);
+
+        if (error)
+                i915_error_state_free(dev, error);
 }
 
 /**