[Mesa-dev] [PATCH 2/3] i965: add noise padding to buffer object and function to check if noise is correct

[kevin.rogovin at intel.com]

From: Kevin Rogovin <kevin.rogovin at intel.com>

Signed-off-by: Kevin Rogovin <kevin.rogovin at intel.com>
---
 src/mesa/drivers/dri/i965/brw_bufmgr.c | 68 +++++++++++++++++++++++++++++++++-
 src/mesa/drivers/dri/i965/brw_bufmgr.h | 12 ++++++
 2 files changed, 79 insertions(+), 1 deletion(-)

diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.c b/src/mesa/drivers/dri/i965/brw_bufmgr.c
index 52b5bf9..7167165 100644
--- a/src/mesa/drivers/dri/i965/brw_bufmgr.c
+++ b/src/mesa/drivers/dri/i965/brw_bufmgr.c
@@ -367,7 +367,14 @@ retry:
       bo->size = bo_size;
       bo->idle = true;
 
-      struct drm_i915_gem_create create = { .size = bo_size };
+      bo->padding.size = 0;
+      bo->padding.value = NULL;
+      bo->padding.tmp = NULL;
+      if (unlikely(INTEL_DEBUG & DEBUG_OUT_OF_BOUND_CHK)) {
+         bo->padding.size = getpagesize();
+      }
+
+      struct drm_i915_gem_create create = { .size = bo_size + bo->padding.size };
 
       /* All new BOs we get from the kernel are zeroed, so we don't need to
        * worry about that here.
@@ -378,6 +385,31 @@ retry:
          goto err;
       }
 
+      if (unlikely(bo->padding.size > 0)) {
+         struct drm_i915_gem_pwrite pwrite;
+
+         bo->padding.value = calloc(bo->padding.size, 1);
+         bo->padding.tmp = calloc(bo->padding.size, 1);
+         if (!bo->padding.value || !bo->padding.tmp) {
+            goto err_free;
+         }
+
+         for (uint32_t i = 0; i < bo->padding.size; ++i) {
+            bo->padding.value[i] = rand() & 0xFF;
+         }
+
+         pwrite.handle = create.handle;
+         pwrite.pad = 0;
+         pwrite.offset = bo_size;
+         pwrite.size = bo->padding.size;
+         pwrite.data_ptr = (__u64) (uintptr_t) bo->padding.value;
+         ret = drmIoctl(bufmgr->fd, DRM_IOCTL_I915_GEM_PWRITE, &pwrite);
+
+         if (ret != 0) {
+            goto err_free;
+         }
+      }
+
       bo->gem_handle = create.handle;
 
       bo->bufmgr = bufmgr;
@@ -424,6 +456,26 @@ err:
    return NULL;
 }
 
+bool
+brw_bo_padding_is_good(struct brw_bo *bo)
+{
+   if (bo->padding.size > 0) {
+      struct drm_i915_gem_pread pread;
+      int ret;
+
+      assert(bo->padding.tmp && bo->padding.value);
+      pread.handle = bo->gem_handle;
+      pread.pad = 0;
+      pread.offset = bo->size;
+      pread.size = bo->padding.size;
+      pread.data_ptr = (__u64) (uintptr_t) bo->padding.tmp;
+      ret = drmIoctl(bo->bufmgr->fd, DRM_IOCTL_I915_GEM_PREAD, &pread);
+      assert(ret == 0);
+      return memcmp(bo->padding.tmp, bo->padding.value, bo->padding.size) == 0;
+   }
+   return true;
+}
+
 struct brw_bo *
 brw_bo_alloc(struct brw_bufmgr *bufmgr,
              const char *name, uint64_t size, uint64_t alignment)
@@ -598,6 +650,17 @@ bo_free(struct brw_bo *bo)
       DBG("DRM_IOCTL_GEM_CLOSE %d failed (%s): %s\n",
           bo->gem_handle, bo->name, strerror(errno));
    }
+
+   if (unlikely(INTEL_DEBUG & DEBUG_OUT_OF_BOUND_CHK)) {
+      if (bo->padding.value) {
+         free(bo->padding.value);
+      }
+
+      if (bo->padding.tmp) {
+         free(bo->padding.tmp);
+      }
+   }
+
    free(bo);
 }
 
@@ -1156,6 +1219,9 @@ brw_bo_gem_create_from_prime(struct brw_bufmgr *bufmgr, int prime_fd)
    bo->name = "prime";
    bo->reusable = false;
    bo->external = true;
+   bo->padding.size = 0;
+   bo->padding.value = NULL;
+   bo->padding.tmp = NULL;
 
    struct drm_i915_gem_get_tiling get_tiling = { .handle = bo->gem_handle };
    if (drmIoctl(bufmgr->fd, DRM_IOCTL_I915_GEM_GET_TILING, &get_tiling))
diff --git a/src/mesa/drivers/dri/i965/brw_bufmgr.h b/src/mesa/drivers/dri/i965/brw_bufmgr.h
index 0ae541c..4fff866 100644
--- a/src/mesa/drivers/dri/i965/brw_bufmgr.h
+++ b/src/mesa/drivers/dri/i965/brw_bufmgr.h
@@ -165,6 +165,16 @@ struct brw_bo {
     * Boolean of whether this buffer is cache coherent
     */
    bool cache_coherent;
+
+   /**
+    * pointer and size to memory holding values for padding for the
+    * purpose of checking out-of-bound writes.
+    */
+   struct {
+      uint32_t size;
+      uint8_t *value;
+      uint8_t *tmp;
+   } padding;
 };
 
 #define BO_ALLOC_BUSY       (1<<0)
@@ -342,6 +352,8 @@ uint32_t brw_bo_export_gem_handle(struct brw_bo *bo);
 int brw_reg_read(struct brw_bufmgr *bufmgr, uint32_t offset,
                  uint64_t *result);
 
+bool brw_bo_padding_is_good(struct brw_bo *bo);
+
 /** @{ */
 
 #if defined(__cplusplus)
-- 
2.7.4