diff options
Diffstat (limited to 'tests/libs/elftls_dtv_resize_helper.cpp')
-rw-r--r-- | tests/libs/elftls_dtv_resize_helper.cpp | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/tests/libs/elftls_dtv_resize_helper.cpp b/tests/libs/elftls_dtv_resize_helper.cpp new file mode 100644 index 000000000..125f8e84f --- /dev/null +++ b/tests/libs/elftls_dtv_resize_helper.cpp @@ -0,0 +1,224 @@ +/* + * Copyright (C) 2024 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 <dlfcn.h> +#include <stdio.h> +#include <stdlib.h> + +#include <functional> +#include <iostream> + +#include <android-base/test_utils.h> + +#include "bionic/pthread_internal.h" + +constexpr bool kDumpModulesForDebugging = false; + +// The old external/libcxx doesn't have operator<< for nullptr. +// TODO(b/175635923): Remove this hack after upgrading libc++. +template <class T> +T fix_nullptr(T&& arg) { + return arg; +} +void* fix_nullptr(nullptr_t arg) { + return static_cast<void*>(arg); +} + +template <class Val1, class Val2, class Compare> +void check(int line, const char* val1_expr, Val1&& val1, const char* val2_expr, Val2&& val2, + Compare compare) { + if (!compare(val1, val2)) { + std::cerr << __FILE__ << ":" << line << ": assertion failed: LHS(" << val1_expr << ") is " + << fix_nullptr(val1) << ", RHS(" << val2_expr << ") is " << fix_nullptr(val2) << "\n" + << std::flush; + abort(); + } +} + +#define ASSERT_EQ(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::equal_to()) +#define ASSERT_NE(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::not_equal_to()) +#define ASSERT_LT(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::less()) +#define ASSERT_LE(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::less_equal()) + +static size_t highest_loaded_modid() { + size_t result = 0; + auto update_result = [](struct dl_phdr_info* info, size_t size __unused, void* data) { + size_t& result = *reinterpret_cast<size_t*>(data); + if (kDumpModulesForDebugging) { + fprintf(stderr, "module %s: TLS modid %zu\n", info->dlpi_name, info->dlpi_tls_modid); + } + result = std::max(result, info->dlpi_tls_modid); + return 0; + }; + dl_iterate_phdr(update_result, &result); + return result; +} + +static TlsDtv* dtv() { + return __get_tcb_dtv(__get_bionic_tcb()); +} + +static size_t highest_modid_in_dtv() { + TlsDtv* current_dtv = dtv(); + size_t result = 0; + for (size_t i = 0; i < current_dtv->count; ++i) { + if (current_dtv->modules[i] != nullptr) { + result = __tls_module_idx_to_id(i); + } + } + return result; +} + +// Unused, but ensures that the test executable has a TLS segment. With a +// new-enough libc++_static.a, the test executable will tend to has a TLS +// segment to hold the libc++ EH globals pointer. +__thread int g_tls_var_placeholder = 42; + +int main() { + // Prevent this TLS variable from being optimized away. + ASSERT_EQ(42, g_tls_var_placeholder); + + auto load_lib = [](const char* soname) { + void* lib = dlopen(soname, RTLD_LOCAL | RTLD_NOW); + ASSERT_NE(nullptr, lib); + auto func = reinterpret_cast<int (*)()>(dlsym(lib, "bump")); + ASSERT_NE(nullptr, func); + return func; + }; + + static_assert(sizeof(TlsDtv) == 3 * sizeof(void*), + "This test assumes that the Dtv has a 3-word header"); + + // Initially there are 2-4 modules: + // - 1: test executable + // - 2: libc + // - 3: libc++ (when using a new-enough libc++) + // - 4: libclang_rt.hwasan (when running with HWASan) + size_t first_filler_modid = highest_loaded_modid() + 1; + ASSERT_LE(2, highest_loaded_modid()); + ASSERT_LE(highest_loaded_modid(), 4); + + // The initial DTV is an empty DTV with no generation and a size of 0. + TlsDtv* zero_dtv = dtv(); + ASSERT_EQ(0u, zero_dtv->count); + ASSERT_EQ(nullptr, zero_dtv->next); + ASSERT_EQ(kTlsGenerationNone, zero_dtv->generation); + + // Load a module. The DTV is still empty unless the TLS variable is accessed. + auto func1 = load_lib("libtest_elftls_dynamic_filler_1.so"); + ASSERT_EQ(zero_dtv, dtv()); + ASSERT_EQ(first_filler_modid, highest_loaded_modid()); + + // After accessing a TLS variable, the DTV should be initialized. It should be + // 8 words in size, with a 5-entry capacity. + ASSERT_EQ(101, func1()); + TlsDtv* initial_dtv = dtv(); + ASSERT_EQ(5u, dtv()->count); + ASSERT_EQ(zero_dtv, initial_dtv->next); + ASSERT_LT(0u, initial_dtv->generation); + ASSERT_EQ(first_filler_modid, highest_modid_in_dtv()); + ASSERT_NE(nullptr, initial_dtv->modules[__tls_module_id_to_idx(first_filler_modid)]); + + size_t current_generation = initial_dtv->generation; + + // Fill the rest of the DTV up. (i.e. Ensure that exactly 5 modules with TLS + // segments are loaded.) + auto fill_entry = [&](size_t modid, const char* soname, int tls_var_value) { + if (highest_modid_in_dtv() == modid - 1) { + auto func = load_lib(soname); + + // Loading the module doesn't affect the DTV yet. + ASSERT_EQ(initial_dtv, dtv()); + ASSERT_EQ(modid, highest_loaded_modid()); + ASSERT_EQ(modid - 1, highest_modid_in_dtv()); + ASSERT_EQ(current_generation, initial_dtv->generation); + + // Access the TLS variable, which will allocate it in the DTV. + ASSERT_EQ(tls_var_value, func()); + + // Verify allocation and a bumped generation. + ASSERT_EQ(initial_dtv, dtv()); + ASSERT_EQ(modid, highest_modid_in_dtv()); + ASSERT_LT(current_generation, initial_dtv->generation); + current_generation = initial_dtv->generation; + } + }; + + fill_entry(4u, "libtest_elftls_dynamic_filler_2.so", 201); + fill_entry(5u, "libtest_elftls_dynamic_filler_3.so", 301); + ASSERT_EQ(5u, highest_modid_in_dtv()); + + // Load module 6, which will require doubling the size of the DTV. + auto func4 = load_lib("libtest_elftls_dynamic_filler_4.so"); + ASSERT_EQ(6u, highest_loaded_modid()); + ASSERT_EQ(5u, highest_modid_in_dtv()); + ASSERT_EQ(initial_dtv, dtv()); + + // Access a TLS variable from the first filler module. + ASSERT_EQ(102, func1()); + ASSERT_EQ(5u, highest_modid_in_dtv()); +#if defined(__aarch64__) + // The arm64 TLSDESC resolver doesn't update the DTV if it is new enough for + // the given access. + ASSERT_EQ(initial_dtv, dtv()); + ASSERT_EQ(5u, dtv()->count); + ASSERT_EQ(current_generation, dtv()->generation); +#else + // __tls_get_addr updates the DTV anytime the generation counter changes, but + // the highest modid in the DTV is still 5, because module 6 hasn't been + // allocated yet. + ASSERT_NE(initial_dtv, dtv()); + ASSERT_EQ(13u, dtv()->count); + ASSERT_LT(current_generation, dtv()->generation); +#endif + + // Accessing the TLS variable in the latest module will always expand the DTV. + ASSERT_EQ(401, func4()); + TlsDtv* new_dtv = dtv(); + ASSERT_NE(initial_dtv, new_dtv); + ASSERT_EQ(initial_dtv, new_dtv->next); + ASSERT_EQ(13u, new_dtv->count); + ASSERT_LT(current_generation, new_dtv->generation); + ASSERT_EQ(6u, highest_modid_in_dtv()); + current_generation = new_dtv->generation; + + // Load one more filler, module 7. + auto func5 = load_lib("libtest_elftls_dynamic_filler_5.so"); + ASSERT_EQ(103, func1()); + ASSERT_EQ(402, func4()); + ASSERT_EQ(6u, highest_modid_in_dtv()); + ASSERT_EQ(501, func5()); + ASSERT_EQ(7u, highest_modid_in_dtv()); + + // Verify that no new DTV has been allocated. + ASSERT_EQ(new_dtv, dtv()); + ASSERT_EQ(13u, new_dtv->count); + ASSERT_LT(current_generation, new_dtv->generation); + + return 0; +} |