diff options
| -rw-r--r-- | drivers/gpu/drm/i915/i915_drv.h | 11 | ||||
| -rw-r--r-- | drivers/gpu/drm/i915/i915_perf.c | 46 |
2 files changed, 32 insertions, 25 deletions
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h index ff3574a56812..080dcb0c5bd6 100644 --- a/drivers/gpu/drm/i915/i915_drv.h +++ b/drivers/gpu/drm/i915/i915_drv.h @@ -2372,6 +2372,17 @@ struct drm_i915_private { u8 *vaddr; int format; int format_size; + + /** + * Although we can always read back the head + * pointer register, we prefer to avoid + * trusting the HW state, just to avoid any + * risk that some hardware condition could + * somehow bump the head pointer unpredictably + * and cause us to forward the wrong OA buffer + * data to userspace. + */ + u32 head; } oa_buffer; u32 gen7_latched_oastatus1; diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c index e1158893c6cb..838ebc03976f 100644 --- a/drivers/gpu/drm/i915/i915_perf.c +++ b/drivers/gpu/drm/i915/i915_perf.c @@ -322,9 +322,8 @@ struct perf_open_properties { static bool gen7_oa_buffer_is_empty_fop_unlocked(struct drm_i915_private *dev_priv) { int report_size = dev_priv->perf.oa.oa_buffer.format_size; - u32 oastatus2 = I915_READ(GEN7_OASTATUS2); u32 oastatus1 = I915_READ(GEN7_OASTATUS1); - u32 head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK; + u32 head = dev_priv->perf.oa.oa_buffer.head; u32 tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK; return OA_TAKEN(tail, head) < @@ -458,16 +457,24 @@ static int gen7_append_oa_reports(struct i915_perf_stream *stream, return -EIO; head = *head_ptr - gtt_offset; + + /* An out of bounds or misaligned head pointer implies a driver bug + * since we are in full control of head pointer which should only + * be incremented by multiples of the report size (notably also + * all a power of two). + */ + if (WARN_ONCE(head > OA_BUFFER_SIZE || head % report_size, + "Inconsistent OA buffer head pointer = %u\n", head)) + return -EIO; + tail -= gtt_offset; /* The OA unit is expected to wrap the tail pointer according to the OA - * buffer size and since we should never write a misaligned head - * pointer we don't expect to read one back either... + * buffer size */ - if (tail > OA_BUFFER_SIZE || head > OA_BUFFER_SIZE || - head % report_size) { - DRM_ERROR("Inconsistent OA buffer pointer (head = %u, tail = %u): force restart\n", - head, tail); + if (tail > OA_BUFFER_SIZE) { + DRM_ERROR("Inconsistent OA buffer tail pointer = %u: force restart\n", + tail); dev_priv->perf.oa.ops.oa_disable(dev_priv); dev_priv->perf.oa.ops.oa_enable(dev_priv); *head_ptr = I915_READ(GEN7_OASTATUS2) & @@ -562,8 +569,6 @@ static int gen7_oa_read(struct i915_perf_stream *stream, size_t *offset) { struct drm_i915_private *dev_priv = stream->dev_priv; - int report_size = dev_priv->perf.oa.oa_buffer.format_size; - u32 oastatus2; u32 oastatus1; u32 head; u32 tail; @@ -572,10 +577,9 @@ static int gen7_oa_read(struct i915_perf_stream *stream, if (WARN_ON(!dev_priv->perf.oa.oa_buffer.vaddr)) return -EIO; - oastatus2 = I915_READ(GEN7_OASTATUS2); oastatus1 = I915_READ(GEN7_OASTATUS1); - head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK; + head = dev_priv->perf.oa.oa_buffer.head; tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK; /* XXX: On Haswell we don't have a safe way to clear oastatus1 @@ -616,10 +620,9 @@ static int gen7_oa_read(struct i915_perf_stream *stream, dev_priv->perf.oa.ops.oa_disable(dev_priv); dev_priv->perf.oa.ops.oa_enable(dev_priv); - oastatus2 = I915_READ(GEN7_OASTATUS2); oastatus1 = I915_READ(GEN7_OASTATUS1); - head = oastatus2 & GEN7_OASTATUS2_HEAD_MASK; + head = dev_priv->perf.oa.oa_buffer.head; tail = oastatus1 & GEN7_OASTATUS1_TAIL_MASK; } @@ -635,17 +638,6 @@ static int gen7_oa_read(struct i915_perf_stream *stream, ret = gen7_append_oa_reports(stream, buf, count, offset, &head, tail); - /* All the report sizes are a power of two and the - * head should always be incremented by some multiple - * of the report size. - * - * A warning here, but notably if we later read back a - * misaligned pointer we will treat that as a bug since - * it could lead to a buffer overrun. - */ - WARN_ONCE(head & (report_size - 1), - "i915: Writing misaligned OA head pointer"); - /* Note: we update the head pointer here even if an error * was returned since the error may represent a short read * where some some reports were successfully copied. @@ -653,6 +645,7 @@ static int gen7_oa_read(struct i915_perf_stream *stream, I915_WRITE(GEN7_OASTATUS2, ((head & GEN7_OASTATUS2_HEAD_MASK) | OA_MEM_SELECT_GGTT)); + dev_priv->perf.oa.oa_buffer.head = head; return ret; } @@ -833,7 +826,10 @@ static void gen7_init_oa_buffer(struct drm_i915_private *dev_priv) * before OASTATUS1, but after OASTATUS2 */ I915_WRITE(GEN7_OASTATUS2, gtt_offset | OA_MEM_SELECT_GGTT); /* head */ + dev_priv->perf.oa.oa_buffer.head = gtt_offset; + I915_WRITE(GEN7_OABUFFER, gtt_offset); + I915_WRITE(GEN7_OASTATUS1, gtt_offset | OABUFFER_SIZE_16M); /* tail */ /* On Haswell we have to track which OASTATUS1 flags we've |