platform_bionic/linker/linker_block_allocator_test.cpp
Eric Miao 08cf949855 Change default block size alignment to be 4 for memory saving on 32-bit arch
For a 32-bit userspace, `struct LinkedListEntry` takes 8 bytes for
storing the two pointers, a default block allocator size alignment of
16-bytes would waste 50% of memory. By changing the alignment to size
of a pointer, it saves >1MB memory postboot on wembley device.

Bug: http://b/206889551
Test: bionic-unit-tests
Change-Id: Ie92399c9bb3971f631396ee09bbbfd7eb17dc1a7
2022-02-03 16:55:37 -08:00

146 lines
4.3 KiB
C++

/*
* Copyright (C) 2013 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <gtest/gtest.h>
#include "linker_block_allocator.h"
#include <unistd.h>
namespace {
struct test_struct_nominal {
void* pointer;
ssize_t value;
};
/*
* this one has size below kBlockSizeAlign
*/
struct test_struct_small {
char str[3];
};
struct test_struct_max_align {
char str[16];
} __attribute__((aligned(16)));
/*
* 1009 byte struct (1009 is prime)
*/
struct test_struct_larger {
char str[1009];
};
static size_t kPageSize = sysconf(_SC_PAGE_SIZE);
template <typename Element>
void linker_allocator_test_helper() {
LinkerTypeAllocator<Element> allocator;
Element* ptr1 = allocator.alloc();
ASSERT_TRUE(ptr1 != nullptr);
ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % kBlockSizeAlign);
ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % alignof(Element));
Element* ptr2 = allocator.alloc();
ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % kBlockSizeAlign);
ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % alignof(Element));
ASSERT_TRUE(ptr2 != nullptr);
// they should be next to each other.
size_t dist = __BIONIC_ALIGN(MAX(sizeof(Element), kBlockSizeMin), kBlockSizeAlign);
ASSERT_EQ(reinterpret_cast<uint8_t*>(ptr1) + dist, reinterpret_cast<uint8_t*>(ptr2));
allocator.free(ptr1);
allocator.free(ptr2);
}
}; // anonymous namespace
TEST(linker_allocator, test_nominal) {
linker_allocator_test_helper<test_struct_nominal>();
}
TEST(linker_allocator, test_small) {
linker_allocator_test_helper<test_struct_small>();
}
TEST(linker_allocator, test_max_align) {
linker_allocator_test_helper<test_struct_max_align>();
}
TEST(linker_allocator, test_larger) {
linker_allocator_test_helper<test_struct_larger>();
LinkerTypeAllocator<test_struct_larger> allocator;
// lets allocate until we reach next page.
size_t n = kPageSize / sizeof(test_struct_larger) + 1;
for (size_t i=0; i<n; ++i) {
ASSERT_TRUE(allocator.alloc() != nullptr);
}
test_struct_larger* ptr_to_free = allocator.alloc();
ASSERT_TRUE(ptr_to_free != nullptr);
}
static void protect_all() {
LinkerTypeAllocator<test_struct_larger> allocator;
// number of allocs to reach the end of first page
size_t n = kPageSize/sizeof(test_struct_larger) - 1;
test_struct_larger* page1_ptr = allocator.alloc();
for (size_t i=0; i<n; ++i) {
allocator.alloc();
}
test_struct_larger* page2_ptr = allocator.alloc();
allocator.protect_all(PROT_READ);
allocator.protect_all(PROT_READ | PROT_WRITE);
// check access
page2_ptr->str[23] = 27;
page1_ptr->str[13] = 11;
allocator.protect_all(PROT_READ);
fprintf(stderr, "trying to access protected page");
// this should result in segmentation fault
page1_ptr->str[11] = 7;
}
TEST(linker_allocator, test_protect) {
testing::FLAGS_gtest_death_test_style = "threadsafe";
ASSERT_EXIT(protect_all(), testing::KilledBySignal(SIGSEGV), "trying to access protected page");
}