Add test mode to ignore allocation hints

backes · Commit Bot · commit b53ff5f4e318 · 2019-09-16T15:18:27.000Z
This randomizes new memory allocations and reservations. It's currently used to test far jump tables in wasm better, but might be helpful generally for testing arbitrary virtual memory layouts. R=mstarzinger@chromium.org Bug: v8:9477 Change-Id: Ie60b7c6dd3c4cd0f3b9eb8e2172912e0851c357d Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1803340 Commit-Queue: Clemens Hammacher <clemensh@chromium.org> Reviewed-by: Andreas Haas <ahaas@chromium.org> Cr-Commit-Position: refs/heads/master@{#63802}
diff --git a/src/flags/flag-definitions.h b/src/flags/flag-definitions.h
@@ -967,6 +967,10 @@ DEFINE_BOOL(gc_experiment_less_compaction, false,
 
 DEFINE_BOOL(disable_abortjs, false, "disables AbortJS runtime function")
 
+DEFINE_BOOL(randomize_all_allocations, false,
+            "randomize virtual memory reservations by ignoring any hints "
+            "passed when allocating pages")
+
 DEFINE_BOOL(manual_evacuation_candidates_selection, false,
             "Test mode only flag. It allows an unit test to select evacuation "
             "candidates pages (requires --stress_compaction).")
diff --git a/src/utils/allocation.cc b/src/utils/allocation.cc
@@ -10,6 +10,7 @@
 #include "src/base/logging.h"
 #include "src/base/page-allocator.h"
 #include "src/base/platform/platform.h"
+#include "src/flags/flags.h"
 #include "src/init/v8.h"
 #include "src/sanitizer/lsan-page-allocator.h"
 #include "src/utils/memcopy.h"
@@ -166,6 +167,9 @@ void* AllocatePages(v8::PageAllocator* page_allocator, void* hint, size_t size,
   DCHECK_NOT_NULL(page_allocator);
   DCHECK_EQ(hint, AlignedAddress(hint, alignment));
   DCHECK(IsAligned(size, page_allocator->AllocatePageSize()));
+  if (FLAG_randomize_all_allocations) {
+    hint = page_allocator->GetRandomMmapAddr();
+  }
   void* result = nullptr;
   for (int i = 0; i < kAllocationTries; ++i) {
     result = page_allocator->AllocatePages(hint, size, alignment, access);
diff --git a/test/mjsunit/wasm/multiple-code-spaces.js b/test/mjsunit/wasm/multiple-code-spaces.js
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Flags: --allow-natives-syntax
+// Flags: --allow-natives-syntax --randomize-all-allocations
 // Flags: --wasm-far-jump-table --wasm-max-initial-code-space-reservation=1
 
 load('test/mjsunit/wasm/wasm-module-builder.js');
