From: Brad Volkin <bradley.d.volkin@xxxxxxxxx>
Previously we couldn't trust the user-supplied batch length because
it came directly from userspace (i.e. untrusted code). It would have
affected what commands software parsed without regard to what hardware
would actually execute, leaving a potential hole.
With the parser now copying the user supplied batch buffer and writing
MI_NOP commands to any space after the copied region, we can safely use
the batch length input. This should be a performance win as the actual
batch length is frequently much smaller than the allocated object size.
Signed-off-by: Brad Volkin <bradley.d.volkin@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_cmd_parser.c | 20 +++++++++++---------
drivers/gpu/drm/i915/i915_drv.h | 1 +
drivers/gpu/drm/i915/i915_gem_execbuffer.c | 1 +
3 files changed, 13 insertions(+), 9 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_cmd_parser.c b/drivers/gpu/drm/i915/i915_cmd_parser.c
index 18788df..2470d3b 100644
--- a/drivers/gpu/drm/i915/i915_cmd_parser.c
+++ b/drivers/gpu/drm/i915/i915_cmd_parser.c
@@ -833,7 +833,8 @@ finish:
/* Returns a vmap'd pointer to dest_obj, which the caller must unmap */
static u32 *copy_batch(struct drm_i915_gem_object *dest_obj,
- struct drm_i915_gem_object *src_obj)
+ struct drm_i915_gem_object *src_obj,
+ u32 batch_len)
{
int ret = 0;
int needs_clflush = 0;
@@ -853,7 +854,7 @@ static u32 *copy_batch(struct drm_i915_gem_object *dest_obj,
}
if (needs_clflush)
- drm_clflush_virt_range((char *)src_addr, src_obj->base.size);
+ drm_clflush_virt_range((char *)src_addr, batch_len);
ret = i915_gem_object_set_to_cpu_domain(dest_obj, true);
if (ret) {
@@ -868,10 +869,10 @@ static u32 *copy_batch(struct drm_i915_gem_object *dest_obj,
goto unmap_src;
}
- memcpy(dest_addr, src_addr, src_obj->base.size);
- if (dest_obj->base.size > src_obj->base.size)
- memset((u8 *)dest_addr + src_obj->base.size, 0,
- dest_obj->base.size - src_obj->base.size);
+ memcpy(dest_addr, src_addr, batch_len);
+ if (dest_obj->base.size > batch_len)
+ memset((u8 *)dest_addr + batch_len, 0,
+ dest_obj->base.size - batch_len);
unmap_src:
vunmap(src_addr);
@@ -1015,6 +1016,7 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
struct drm_i915_gem_object *batch_obj,
struct drm_i915_gem_object *shadow_batch_obj,
u32 batch_start_offset,
+ u32 batch_len,
bool is_master)
{
int ret = 0;
@@ -1022,7 +1024,7 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
struct drm_i915_cmd_descriptor default_desc = { 0 };
bool oacontrol_set = false; /* OACONTROL tracking. See check_cmd() */
- batch_base = copy_batch(shadow_batch_obj, batch_obj);
+ batch_base = copy_batch(shadow_batch_obj, batch_obj, batch_len);
if (IS_ERR(batch_base)) {
DRM_DEBUG_DRIVER("CMD: Failed to copy batch\n");
return PTR_ERR(batch_base);
@@ -1031,11 +1033,11 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
cmd = batch_base + (batch_start_offset / sizeof(*cmd));
/*
- * We use the source object's size because the shadow object is as
+ * We use the batch length as size because the shadow object is as
* large or larger and copy_batch() will write MI_NOPs to the extra
* space. Parsing should be faster in some cases this way.
*/
- batch_end = cmd + (batch_obj->base.size / sizeof(*batch_end));
+ batch_end = cmd + (batch_len / sizeof(*batch_end));
while (cmd < batch_end) {
const struct drm_i915_cmd_descriptor *desc;
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index a6b903d..49bcf79 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2627,6 +2627,7 @@ int i915_parse_cmds(struct intel_engine_cs *ring,
struct drm_i915_gem_object *batch_obj,
struct drm_i915_gem_object *shadow_batch_obj,
u32 batch_start_offset,
+ u32 batch_len,
bool is_master);
/* i915_suspend.c */
diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 908cf48..69ce030 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -1388,6 +1388,7 @@ i915_gem_do_execbuffer(struct drm_device *dev, void *data,
batch_obj,
shadow_batch_obj,
args->batch_start_offset,
+ args->batch_len,
file->is_master);
if (ret)
goto err;
--
1.8.3.2
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