78 lines
2.6 KiB
C++
78 lines
2.6 KiB
C++
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// Copyright 2022 The Chromium Authors
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#include "base/profiler/stack_buffer.h"
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#include "base/memory/aligned_memory.h"
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#include "build/build_config.h"
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#include "testing/gtest/include/gtest/gtest.h"
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#if BUILDFLAG(IS_CHROMEOS)
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#include "base/bits.h"
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#include "base/memory/page_size.h"
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#endif // #if BUILDFLAG(IS_CHROMEOS)
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namespace base {
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TEST(StackBufferTest, BufferAllocated) {
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const unsigned int kBufferSize = 32 * 1024;
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StackBuffer stack_buffer(kBufferSize);
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EXPECT_EQ(stack_buffer.size(), kBufferSize);
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// Without volatile, the compiler could simply optimize away the entire for
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// loop below.
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volatile uintptr_t* buffer = stack_buffer.buffer();
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ASSERT_NE(nullptr, buffer);
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EXPECT_TRUE(IsAligned(const_cast<uintptr_t*>(buffer),
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StackBuffer::kPlatformStackAlignment));
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// Memory pointed to by buffer should be writable.
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for (unsigned int i = 0; i < (kBufferSize / sizeof(buffer[0])); i++) {
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buffer[i] = i;
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EXPECT_EQ(buffer[i], i);
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}
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}
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#if BUILDFLAG(IS_CHROMEOS)
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TEST(StackBufferTest, MarkBufferContentsAsUnneeded) {
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const unsigned int kBufferSize = 32 * GetPageSize();
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StackBuffer stack_buffer(kBufferSize);
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volatile uintptr_t* buffer = stack_buffer.buffer();
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ASSERT_NE(nullptr, buffer);
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// Force the kernel to allocate backing store for the buffer.
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for (unsigned int i = 0; i < (kBufferSize / sizeof(uintptr_t)); i++) {
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buffer[i] = i;
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EXPECT_EQ(buffer[i], i);
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}
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// Tell kernel to discard (most of) the memory.
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constexpr size_t kUndiscardedElements = 100;
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stack_buffer.MarkUpperBufferContentsAsUnneeded(kUndiscardedElements *
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sizeof(buffer[0]));
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// The first 100 elements shouldn't have been discarded.
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for (size_t i = 0; i < kUndiscardedElements; i++) {
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EXPECT_EQ(buffer[i], i);
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}
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// Pages past the discard point should be zero-filled now.
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const size_t kExpectedDiscardStartPoint =
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bits::AlignUp(kUndiscardedElements * sizeof(buffer[0]), GetPageSize()) /
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sizeof(buffer[0]);
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for (size_t i = kExpectedDiscardStartPoint;
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i < kBufferSize / sizeof(buffer[0]); i++) {
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EXPECT_EQ(buffer[i], 0U);
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}
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// Writing to the memory (both discarded and undiscarded parts) shouldn't
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// cause segmentation faults and should remember the value we write.
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for (unsigned int i = 0; i < (kBufferSize / sizeof(buffer[0])); i++) {
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buffer[i] = i + 7;
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EXPECT_EQ(buffer[i], i + 7);
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}
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}
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#endif // #if BUILDFLAG(IS_CHROMEOS)
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} // namespace base
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