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/*
* 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;
}
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