Add SHA1 data checksum to on-disk shader cache

content/browser/gpu/gpu_process_host.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/gpu/gpu_process_host.h"
 
 #include <stddef.h>
 
 #include <algorithm>
 #include <list>
@@ skipping 1133 matching lines @@
         // The GPU process is too unstable to use. Disable it for current
         // session.
         hardware_gpu_enabled_ = false;
         GpuDataManagerImpl::GetInstance()->DisableHardwareAcceleration();
 #endif
       }
     }
   }
 }
 
-std::string GpuProcessHost::GetShaderPrefixKey() {
-  if (shader_prefix_key_.empty()) {
+std::string GpuProcessHost::GetShaderPrefixKey(const std::string& shader) {
+  if (shader_prefix_key_info_.empty()) {
     gpu::GPUInfo info = GpuDataManagerImpl::GetInstance()->GetGPUInfo();
 
-    std::string in_str = GetContentClient()->GetProduct() + "-" +
+    shader_prefix_key_info_ =
+        GetContentClient()->GetProduct() + "-" +
 #if defined(OS_ANDROID)
         base::android::BuildInfo::GetInstance()->android_build_fp() + "-" +
 #endif
-        info.gl_vendor + "-" + info.gl_renderer + "-" +
-        info.driver_version + "-" + info.driver_vendor;
-
-    base::Base64Encode(base::SHA1HashString(in_str), &shader_prefix_key_);
+        info.gl_vendor + "-" + info.gl_renderer + "-" + info.driver_version +
+        "-" + info.driver_vendor;
   }
 
-  return shader_prefix_key_;
+  // The shader prefix key is a SHA1 hash of a set of per-machine info, such as
+  // driver version and os version, as well as the shader data being cached.
+  // This ensures both that the shader was not corrupted on disk, as well as
+  // that the shader is correctly configured for the current hardware.
+  std::string prefix;
+  base::Base64Encode(base::SHA1HashString(shader_prefix_key_info_ + shader),
+                     &prefix);
+  return prefix;
 }
 
 void GpuProcessHost::LoadedShader(const std::string& key,
                                   const std::string& data) {
-  std::string prefix = GetShaderPrefixKey();
+  std::string prefix = GetShaderPrefixKey(data);
   if (!key.compare(0, prefix.length(), prefix))

[jbauman, 2017/01/18 01:24:05]

Could you add a UMA histogram for this?

[ericrk, 2017/01/18 19:44:16]

Done.

     Send(new GpuMsg_LoadedShader(data));
 }
 
 void GpuProcessHost::CreateChannelCache(int32_t client_id) {
   TRACE_EVENT0("gpu", "GpuProcessHost::CreateChannelCache");
 
   scoped_refptr<gpu::ShaderDiskCache> cache =
       GetShaderCacheFactorySingleton()->Get(client_id);
   if (!cache.get())
     return;
@@ skipping 10 matching lines @@
 
 void GpuProcessHost::OnCacheShader(int32_t client_id,
                                    const std::string& key,
                                    const std::string& shader) {
   TRACE_EVENT0("gpu", "GpuProcessHost::OnCacheShader");
   ClientIdToShaderCacheMap::iterator iter =
       client_id_to_shader_cache_.find(client_id);
   // If the cache doesn't exist then this is an off the record profile.
   if (iter == client_id_to_shader_cache_.end())
     return;
-  iter->second->Cache(GetShaderPrefixKey() + ":" + key, shader);
+  iter->second->Cache(GetShaderPrefixKey(shader) + ":" + key, shader);
 }
 
 }  // namespace content