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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
*/
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#include <cstdlib>
#include "gc/Memory.h"
#include "jsapi-tests/tests.h"
#if defined(XP_WIN)
# include "util/WindowsWrapper.h"
# include <psapi.h>
#elif defined(__wasi__)
// Nothing.
#else
# include <algorithm>
# include <errno.h>
# include <sys/mman.h>
# include <sys/resource.h>
# include <sys/stat.h>
# include <sys/types.h>
# include <unistd.h>
#endif
BEGIN_TEST(testGCAllocator) {
#ifdef JS_64BIT
// If we're using the scattershot allocator, this test does not apply.
if (js::gc::UsingScattershotAllocator()) {
return true;
}
#endif
size_t PageSize = js::gc::SystemPageSize();
/* Finish any ongoing background free activity. */
js::gc::FinishGC(cx);
bool growUp = false;
CHECK(addressesGrowUp(&growUp));
if (growUp) {
return testGCAllocatorUp(PageSize);
} else {
return testGCAllocatorDown(PageSize);
}
}
static const size_t Chunk = 512 * 1024;
static const size_t Alignment = 2 * Chunk;
static const int MaxTempChunks = 4096;
static const size_t StagingSize = 16 * Chunk;
bool addressesGrowUp(bool* resultOut) {
/*
* Try to detect whether the OS allocates memory in increasing or decreasing
* address order by making several allocations and comparing the addresses.
*/
static const unsigned ChunksToTest = 20;
static const int ThresholdCount = 15;
void* chunks[ChunksToTest];
for (unsigned i = 0; i < ChunksToTest; i++) {
chunks[i] = mapMemory(2 * Chunk);
CHECK(chunks[i]);
}
int upCount = 0;
int downCount = 0;
for (unsigned i = 0; i < ChunksToTest - 1; i++) {
if (chunks[i] < chunks[i + 1]) {
upCount++;
} else {
downCount++;
}
}
for (unsigned i = 0; i < ChunksToTest; i++) {
unmapPages(chunks[i], 2 * Chunk);
}
/* Check results were mostly consistent. */
CHECK(abs(upCount - downCount) >= ThresholdCount);
*resultOut = upCount > downCount;
return true;
}
size_t offsetFromAligned(void* p) { return uintptr_t(p) % Alignment; }
enum AllocType { UseNormalAllocator, UseLastDitchAllocator };
bool testGCAllocatorUp(const size_t PageSize) {
const size_t UnalignedSize = StagingSize + Alignment - PageSize;
void* chunkPool[MaxTempChunks];
// Allocate a contiguous chunk that we can partition for testing.
void* stagingArea = mapMemory(UnalignedSize);
if (!stagingArea) {
return false;
}
// Ensure that the staging area is aligned.
unmapPages(stagingArea, UnalignedSize);
if (offsetFromAligned(stagingArea)) {
const size_t Offset = offsetFromAligned(stagingArea);
// Place the area at the lowest aligned address.
stagingArea = (void*)(uintptr_t(stagingArea) + (Alignment - Offset));
}
mapMemoryAt(stagingArea, StagingSize);
// Make sure there are no available chunks below the staging area.
int tempChunks;
if (!fillSpaceBeforeStagingArea(tempChunks, stagingArea, chunkPool, false)) {
return false;
}
// Unmap the staging area so we can set it up for testing.
unmapPages(stagingArea, StagingSize);
// Check that the first chunk is used if it is aligned.
CHECK(positionIsCorrect("xxooxxx---------", stagingArea, chunkPool,
tempChunks));
// Check that the first chunk is used if it can be aligned.
CHECK(positionIsCorrect("x-ooxxx---------", stagingArea, chunkPool,
tempChunks));
// Check that an aligned chunk after a single unalignable chunk is used.
CHECK(positionIsCorrect("x--xooxxx-------", stagingArea, chunkPool,
tempChunks));
// Check that we fall back to the slow path after two unalignable chunks.
CHECK(positionIsCorrect("x--xx--xoo--xxx-", stagingArea, chunkPool,
tempChunks));
// Check that we also fall back after an unalignable and an alignable chunk.
CHECK(positionIsCorrect("x--xx---x-oo--x-", stagingArea, chunkPool,
tempChunks));
// Check that the last ditch allocator works as expected.
CHECK(positionIsCorrect("x--xx--xx-oox---", stagingArea, chunkPool,
tempChunks, UseLastDitchAllocator));
// Check that the last ditch allocator can deal with naturally aligned chunks.
CHECK(positionIsCorrect("x--xx--xoo------", stagingArea, chunkPool,
tempChunks, UseLastDitchAllocator));
// Clean up.
while (--tempChunks >= 0) {
unmapPages(chunkPool[tempChunks], 2 * Chunk);
}
return true;
}
bool testGCAllocatorDown(const size_t PageSize) {
const size_t UnalignedSize = StagingSize + Alignment - PageSize;
void* chunkPool[MaxTempChunks];
// Allocate a contiguous chunk that we can partition for testing.
void* stagingArea = mapMemory(UnalignedSize);
if (!stagingArea) {
return false;
}
// Ensure that the staging area is aligned.
unmapPages(stagingArea, UnalignedSize);
if (offsetFromAligned(stagingArea)) {
void* stagingEnd = (void*)(uintptr_t(stagingArea) + UnalignedSize);
const size_t Offset = offsetFromAligned(stagingEnd);
// Place the area at the highest aligned address.
stagingArea = (void*)(uintptr_t(stagingEnd) - Offset - StagingSize);
}
mapMemoryAt(stagingArea, StagingSize);
// Make sure there are no available chunks above the staging area.
int tempChunks;
if (!fillSpaceBeforeStagingArea(tempChunks, stagingArea, chunkPool, true)) {
return false;
}
// Unmap the staging area so we can set it up for testing.
unmapPages(stagingArea, StagingSize);
// Check that the first chunk is used if it is aligned.
CHECK(positionIsCorrect("---------xxxooxx", stagingArea, chunkPool,
tempChunks));
// Check that the first chunk is used if it can be aligned.
CHECK(positionIsCorrect("---------xxxoo-x", stagingArea, chunkPool,
tempChunks));
// Check that an aligned chunk after a single unalignable chunk is used.
CHECK(positionIsCorrect("-------xxxoox--x", stagingArea, chunkPool,
tempChunks));
// Check that we fall back to the slow path after two unalignable chunks.
CHECK(positionIsCorrect("-xxx--oox--xx--x", stagingArea, chunkPool,
tempChunks));
// Check that we also fall back after an unalignable and an alignable chunk.
CHECK(positionIsCorrect("-x--oo-x---xx--x", stagingArea, chunkPool,
tempChunks));
// Check that the last ditch allocator works as expected.
CHECK(positionIsCorrect("---xoo-xx--xx--x", stagingArea, chunkPool,
tempChunks, UseLastDitchAllocator));
// Check that the last ditch allocator can deal with naturally aligned chunks.
CHECK(positionIsCorrect("------oox--xx--x", stagingArea, chunkPool,
tempChunks, UseLastDitchAllocator));
// Clean up.
while (--tempChunks >= 0) {
unmapPages(chunkPool[tempChunks], 2 * Chunk);
}
return true;
}
bool fillSpaceBeforeStagingArea(int& tempChunks, void* stagingArea,
void** chunkPool, bool addressesGrowDown) {
// Make sure there are no available chunks before the staging area.
tempChunks = 0;
chunkPool[tempChunks++] = mapMemory(2 * Chunk);
while (tempChunks < MaxTempChunks && chunkPool[tempChunks - 1] &&
(chunkPool[tempChunks - 1] < stagingArea) ^ addressesGrowDown) {
chunkPool[tempChunks++] = mapMemory(2 * Chunk);
if (!chunkPool[tempChunks - 1]) {
break; // We already have our staging area, so OOM here is okay.
}
if ((chunkPool[tempChunks - 1] < chunkPool[tempChunks - 2]) ^
addressesGrowDown) {
break; // The address growth direction is inconsistent!
}
}
// OOM also means success in this case.
if (!chunkPool[tempChunks - 1]) {
--tempChunks;
return true;
}
// Bail if we can't guarantee the right address space layout.
if ((chunkPool[tempChunks - 1] < stagingArea) ^ addressesGrowDown ||
(tempChunks > 1 &&
(chunkPool[tempChunks - 1] < chunkPool[tempChunks - 2]) ^
addressesGrowDown)) {
while (--tempChunks >= 0) {
unmapPages(chunkPool[tempChunks], 2 * Chunk);
}
unmapPages(stagingArea, StagingSize);
return false;
}
return true;
}
bool positionIsCorrect(const char* str, void* base, void** chunkPool,
int tempChunks,
AllocType allocator = UseNormalAllocator) {
// str represents a region of memory, with each character representing a
// region of Chunk bytes. str should contain only x, o and -, where
// x = mapped by the test to set up the initial conditions,
// o = mapped by the GC allocator, and
// - = unmapped.
// base should point to a region of contiguous free memory
// large enough to hold strlen(str) chunks of Chunk bytes.
int len = strlen(str);
int i;
// Find the index of the desired address.
for (i = 0; i < len && str[i] != 'o'; ++i)
;
void* desired = (void*)(uintptr_t(base) + i * Chunk);
// Map the regions indicated by str.
for (i = 0; i < len; ++i) {
if (str[i] == 'x') {
mapMemoryAt((void*)(uintptr_t(base) + i * Chunk), Chunk);
}
}
// Allocate using the GC's allocator.
void* result;
if (allocator == UseNormalAllocator) {
result = js::gc::MapAlignedPages(2 * Chunk, Alignment);
} else {
result = js::gc::TestMapAlignedPagesLastDitch(2 * Chunk, Alignment);
}
// Clean up the mapped regions.
if (result) {
js::gc::UnmapPages(result, 2 * Chunk);
}
for (--i; i >= 0; --i) {
if (str[i] == 'x') {
js::gc::UnmapPages((void*)(uintptr_t(base) + i * Chunk), Chunk);
}
}
// CHECK returns, so clean up on failure.
if (result != desired) {
while (--tempChunks >= 0) {
js::gc::UnmapPages(chunkPool[tempChunks], 2 * Chunk);
}
}
return result == desired;
}
#if defined(XP_WIN)
void* mapMemoryAt(void* desired, size_t length) {
return VirtualAlloc(desired, length, MEM_COMMIT | MEM_RESERVE,
PAGE_READWRITE);
}
void* mapMemory(size_t length) {
return VirtualAlloc(nullptr, length, MEM_COMMIT | MEM_RESERVE,
PAGE_READWRITE);
}
void unmapPages(void* p, size_t size) {
MOZ_ALWAYS_TRUE(VirtualFree(p, 0, MEM_RELEASE));
}
#elif defined(__wasi__)
void* mapMemoryAt(void* desired, size_t length) { return nullptr; }
void* mapMemory(size_t length) {
void* addr = nullptr;
if (int err = posix_memalign(&addr, js::gc::SystemPageSize(), length)) {
MOZ_ASSERT(err == ENOMEM);
}
MOZ_ASSERT(addr);
memset(addr, 0, length);
return addr;
}
void unmapPages(void* p, size_t size) { free(p); }
#else
void* mapMemoryAt(void* desired, size_t length) {
void* region = mmap(desired, length, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON, -1, 0);
if (region == MAP_FAILED) {
return nullptr;
}
if (region != desired) {
if (munmap(region, length)) {
MOZ_RELEASE_ASSERT(errno == ENOMEM);
}
return nullptr;
}
return region;
}
void* mapMemory(size_t length) {
int prot = PROT_READ | PROT_WRITE;
int flags = MAP_PRIVATE | MAP_ANON;
int fd = -1;
off_t offset = 0;
void* region = mmap(nullptr, length, prot, flags, fd, offset);
if (region == MAP_FAILED) {
return nullptr;
}
return region;
}
void unmapPages(void* p, size_t size) {
if (munmap(p, size)) {
MOZ_RELEASE_ASSERT(errno == ENOMEM);
}
}
#endif
END_TEST(testGCAllocator)