0f40a05309
Recently, the maps for an elf in memory might show up looking like: f0000-f1000 0 r-- /system/lib/libc.so f1000-f2000 0 --- f2000-f3000 1000 r-x /system/lib/libc.so f3000-f4000 2000 rw- /system/lib/libc.so The problem is that there is logic in the code that assumed that the map before the execute map must be the read-only map. In the case above, this is not true. Add a new prev_real_map that will point to the previous map that is not one of these empty maps. This will fix the backtraces that look like this: #00 pc 0000000000050d58 /apex/com.android.runtime/lib64/bionic/libc.so!libc.so (offset 0x50000) (syscall+24) (BuildId: 5252408bf30e395d49ee270b54c77ca4) To get rid of the !libc.so and the offset value, which is not correct. Added new unit tests to verify this. Added new offline test which an empty map between read-only and execute map. Before this change, the backtraces had lines like libc.so!libc.so (offset XXX) would be present. Bug: 148075852 Test: Ran unit tests. Change-Id: Ie04bfc96b8f91ed885cb1e655cf1e346efe48a45
263 lines
7.9 KiB
C++
263 lines
7.9 KiB
C++
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <elf.h>
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#include <unistd.h>
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#include <android-base/file.h>
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#include <gtest/gtest.h>
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#include <unwindstack/Elf.h>
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#include <unwindstack/MapInfo.h>
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#include "ElfTestUtils.h"
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#include "MemoryFake.h"
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namespace unwindstack {
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class ElfCacheTest : public ::testing::Test {
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protected:
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static void SetUpTestSuite() { memory_.reset(new MemoryFake); }
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void SetUp() override { Elf::SetCachingEnabled(true); }
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void TearDown() override { Elf::SetCachingEnabled(false); }
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void WriteElfFile(uint64_t offset, TemporaryFile* tf, uint32_t type) {
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ASSERT_TRUE(type == EM_ARM || type == EM_386 || type == EM_X86_64);
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size_t ehdr_size;
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Elf32_Ehdr ehdr32;
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Elf64_Ehdr ehdr64;
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void* ptr;
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if (type == EM_ARM || type == EM_386) {
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ehdr_size = sizeof(ehdr32);
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ptr = &ehdr32;
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TestInitEhdr(&ehdr32, ELFCLASS32, type);
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} else {
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ehdr_size = sizeof(ehdr64);
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ptr = &ehdr64;
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TestInitEhdr(&ehdr64, ELFCLASS64, type);
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}
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ASSERT_EQ(offset, static_cast<uint64_t>(lseek(tf->fd, offset, SEEK_SET)));
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ASSERT_TRUE(android::base::WriteFully(tf->fd, ptr, ehdr_size));
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}
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void VerifyWithinSameMap(bool cache_enabled);
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void VerifySameMap(bool cache_enabled);
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void VerifyWithinSameMapNeverReadAtZero(bool cache_enabled);
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static std::shared_ptr<Memory> memory_;
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};
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std::shared_ptr<Memory> ElfCacheTest::memory_;
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void ElfCacheTest::VerifySameMap(bool cache_enabled) {
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if (!cache_enabled) {
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Elf::SetCachingEnabled(false);
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}
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TemporaryFile tf;
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ASSERT_TRUE(tf.fd != -1);
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WriteElfFile(0, &tf, EM_ARM);
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close(tf.fd);
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uint64_t start = 0x1000;
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uint64_t end = 0x20000;
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MapInfo info1(nullptr, nullptr, start, end, 0, 0x5, tf.path);
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MapInfo info2(nullptr, nullptr, start, end, 0, 0x5, tf.path);
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Elf* elf1 = info1.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf1->valid());
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Elf* elf2 = info2.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf2->valid());
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if (cache_enabled) {
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EXPECT_EQ(elf1, elf2);
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} else {
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EXPECT_NE(elf1, elf2);
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}
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}
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TEST_F(ElfCacheTest, no_caching) {
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VerifySameMap(false);
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}
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TEST_F(ElfCacheTest, caching_invalid_elf) {
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VerifySameMap(true);
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}
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void ElfCacheTest::VerifyWithinSameMap(bool cache_enabled) {
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if (!cache_enabled) {
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Elf::SetCachingEnabled(false);
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}
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TemporaryFile tf;
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ASSERT_TRUE(tf.fd != -1);
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WriteElfFile(0, &tf, EM_ARM);
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WriteElfFile(0x100, &tf, EM_386);
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WriteElfFile(0x200, &tf, EM_X86_64);
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lseek(tf.fd, 0x500, SEEK_SET);
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uint8_t value = 0;
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write(tf.fd, &value, 1);
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close(tf.fd);
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uint64_t start = 0x1000;
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uint64_t end = 0x20000;
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// Will have an elf at offset 0 in file.
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MapInfo info0_1(nullptr, nullptr, start, end, 0, 0x5, tf.path);
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MapInfo info0_2(nullptr, nullptr, start, end, 0, 0x5, tf.path);
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// Will have an elf at offset 0x100 in file.
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MapInfo info100_1(nullptr, nullptr, start, end, 0x100, 0x5, tf.path);
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MapInfo info100_2(nullptr, nullptr, start, end, 0x100, 0x5, tf.path);
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// Will have an elf at offset 0x200 in file.
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MapInfo info200_1(nullptr, nullptr, start, end, 0x200, 0x5, tf.path);
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MapInfo info200_2(nullptr, nullptr, start, end, 0x200, 0x5, tf.path);
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// Will have an elf at offset 0 in file.
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MapInfo info300_1(nullptr, nullptr, start, end, 0x300, 0x5, tf.path);
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MapInfo info300_2(nullptr, nullptr, start, end, 0x300, 0x5, tf.path);
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Elf* elf0_1 = info0_1.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf0_1->valid());
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EXPECT_EQ(ARCH_ARM, elf0_1->arch());
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Elf* elf0_2 = info0_2.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf0_2->valid());
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EXPECT_EQ(ARCH_ARM, elf0_2->arch());
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EXPECT_EQ(0U, info0_1.elf_offset);
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EXPECT_EQ(0U, info0_2.elf_offset);
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if (cache_enabled) {
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EXPECT_EQ(elf0_1, elf0_2);
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} else {
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EXPECT_NE(elf0_1, elf0_2);
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}
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Elf* elf100_1 = info100_1.GetElf(memory_, ARCH_X86);
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ASSERT_TRUE(elf100_1->valid());
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EXPECT_EQ(ARCH_X86, elf100_1->arch());
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Elf* elf100_2 = info100_2.GetElf(memory_, ARCH_X86);
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ASSERT_TRUE(elf100_2->valid());
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EXPECT_EQ(ARCH_X86, elf100_2->arch());
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EXPECT_EQ(0U, info100_1.elf_offset);
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EXPECT_EQ(0U, info100_2.elf_offset);
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if (cache_enabled) {
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EXPECT_EQ(elf100_1, elf100_2);
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} else {
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EXPECT_NE(elf100_1, elf100_2);
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}
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Elf* elf200_1 = info200_1.GetElf(memory_, ARCH_X86_64);
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ASSERT_TRUE(elf200_1->valid());
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EXPECT_EQ(ARCH_X86_64, elf200_1->arch());
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Elf* elf200_2 = info200_2.GetElf(memory_, ARCH_X86_64);
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ASSERT_TRUE(elf200_2->valid());
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EXPECT_EQ(ARCH_X86_64, elf200_2->arch());
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EXPECT_EQ(0U, info200_1.elf_offset);
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EXPECT_EQ(0U, info200_2.elf_offset);
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if (cache_enabled) {
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EXPECT_EQ(elf200_1, elf200_2);
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} else {
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EXPECT_NE(elf200_1, elf200_2);
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}
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Elf* elf300_1 = info300_1.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf300_1->valid());
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EXPECT_EQ(ARCH_ARM, elf300_1->arch());
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Elf* elf300_2 = info300_2.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf300_2->valid());
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EXPECT_EQ(ARCH_ARM, elf300_2->arch());
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EXPECT_EQ(0x300U, info300_1.elf_offset);
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EXPECT_EQ(0x300U, info300_2.elf_offset);
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if (cache_enabled) {
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EXPECT_EQ(elf300_1, elf300_2);
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EXPECT_EQ(elf0_1, elf300_1);
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} else {
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EXPECT_NE(elf300_1, elf300_2);
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EXPECT_NE(elf0_1, elf300_1);
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}
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}
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TEST_F(ElfCacheTest, no_caching_valid_elf_offset_non_zero) {
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VerifyWithinSameMap(false);
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}
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TEST_F(ElfCacheTest, caching_valid_elf_offset_non_zero) {
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VerifyWithinSameMap(true);
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}
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// Verify that when reading from multiple non-zero offsets in the same map
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// that when cached, all of the elf objects are the same.
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void ElfCacheTest::VerifyWithinSameMapNeverReadAtZero(bool cache_enabled) {
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if (!cache_enabled) {
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Elf::SetCachingEnabled(false);
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}
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TemporaryFile tf;
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ASSERT_TRUE(tf.fd != -1);
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WriteElfFile(0, &tf, EM_ARM);
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lseek(tf.fd, 0x500, SEEK_SET);
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uint8_t value = 0;
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write(tf.fd, &value, 1);
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close(tf.fd);
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uint64_t start = 0x1000;
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uint64_t end = 0x20000;
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// Multiple info sections at different offsets will have non-zero elf offsets.
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MapInfo info300_1(nullptr, nullptr, start, end, 0x300, 0x5, tf.path);
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MapInfo info300_2(nullptr, nullptr, start, end, 0x300, 0x5, tf.path);
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MapInfo info400_1(nullptr, nullptr, start, end, 0x400, 0x5, tf.path);
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MapInfo info400_2(nullptr, nullptr, start, end, 0x400, 0x5, tf.path);
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Elf* elf300_1 = info300_1.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf300_1->valid());
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EXPECT_EQ(ARCH_ARM, elf300_1->arch());
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Elf* elf300_2 = info300_2.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf300_2->valid());
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EXPECT_EQ(ARCH_ARM, elf300_2->arch());
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EXPECT_EQ(0x300U, info300_1.elf_offset);
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EXPECT_EQ(0x300U, info300_2.elf_offset);
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if (cache_enabled) {
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EXPECT_EQ(elf300_1, elf300_2);
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} else {
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EXPECT_NE(elf300_1, elf300_2);
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}
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Elf* elf400_1 = info400_1.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf400_1->valid());
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EXPECT_EQ(ARCH_ARM, elf400_1->arch());
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Elf* elf400_2 = info400_2.GetElf(memory_, ARCH_ARM);
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ASSERT_TRUE(elf400_2->valid());
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EXPECT_EQ(ARCH_ARM, elf400_2->arch());
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EXPECT_EQ(0x400U, info400_1.elf_offset);
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EXPECT_EQ(0x400U, info400_2.elf_offset);
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if (cache_enabled) {
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EXPECT_EQ(elf400_1, elf400_2);
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EXPECT_EQ(elf300_1, elf400_1);
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} else {
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EXPECT_NE(elf400_1, elf400_2);
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EXPECT_NE(elf300_1, elf400_1);
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}
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}
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TEST_F(ElfCacheTest, no_caching_valid_elf_offset_non_zero_never_read_at_zero) {
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VerifyWithinSameMapNeverReadAtZero(false);
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}
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TEST_F(ElfCacheTest, caching_valid_elf_offset_non_zero_never_read_at_zero) {
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VerifyWithinSameMapNeverReadAtZero(true);
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}
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} // namespace unwindstack
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