1 /*
2 * Copyright (C) 2024 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <dlfcn.h>
30 #include <stdio.h>
31 #include <stdlib.h>
32
33 #include <functional>
34 #include <iostream>
35
36 #include "bionic/pthread_internal.h"
37
38 constexpr bool kDumpModulesForDebugging = false;
39
40 // The old external/libcxx doesn't have operator<< for nullptr.
41 // TODO(b/175635923): Remove this hack after upgrading libc++.
42 template <class T>
fix_nullptr(T && arg)43 T fix_nullptr(T&& arg) {
44 return arg;
45 }
fix_nullptr(nullptr_t arg)46 void* fix_nullptr(nullptr_t arg) {
47 return static_cast<void*>(arg);
48 }
49
50 template <class Val1, class Val2, class Compare>
check(int line,const char * val1_expr,Val1 && val1,const char * val2_expr,Val2 && val2,Compare compare)51 void check(int line, const char* val1_expr, Val1&& val1, const char* val2_expr, Val2&& val2,
52 Compare compare) {
53 if (!compare(val1, val2)) {
54 std::cerr << __FILE__ << ":" << line << ": assertion failed: LHS(" << val1_expr << ") is "
55 << fix_nullptr(val1) << ", RHS(" << val2_expr << ") is " << fix_nullptr(val2) << "\n"
56 << std::flush;
57 abort();
58 }
59 }
60
61 #define ASSERT_EQ(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::equal_to())
62 #define ASSERT_NE(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::not_equal_to())
63 #define ASSERT_LT(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::less())
64 #define ASSERT_LE(val1, val2) check(__LINE__, #val1, val1, #val2, val2, std::less_equal())
65
highest_loaded_modid()66 static size_t highest_loaded_modid() {
67 size_t result = 0;
68 auto update_result = [](struct dl_phdr_info* info, size_t size __unused, void* data) {
69 size_t& result = *reinterpret_cast<size_t*>(data);
70 if (kDumpModulesForDebugging) {
71 fprintf(stderr, "module %s: TLS modid %zu\n", info->dlpi_name, info->dlpi_tls_modid);
72 }
73 result = std::max(result, info->dlpi_tls_modid);
74 return 0;
75 };
76 dl_iterate_phdr(update_result, &result);
77 return result;
78 }
79
dtv()80 static TlsDtv* dtv() {
81 return __get_tcb_dtv(__get_bionic_tcb());
82 }
83
highest_modid_in_dtv()84 static size_t highest_modid_in_dtv() {
85 TlsDtv* current_dtv = dtv();
86 size_t result = 0;
87 for (size_t i = 0; i < current_dtv->count; ++i) {
88 if (current_dtv->modules[i] != nullptr) {
89 result = __tls_module_idx_to_id(i);
90 }
91 }
92 return result;
93 }
94
95 // Unused, but ensures that the test executable has a TLS segment. With a
96 // new-enough libc++_static.a, the test executable will tend to has a TLS
97 // segment to hold the libc++ EH globals pointer.
98 __thread int g_tls_var_placeholder = 42;
99
main()100 int main() {
101 // Prevent this TLS variable from being optimized away.
102 ASSERT_EQ(42, g_tls_var_placeholder);
103
104 auto load_lib = [](const char* soname) {
105 void* lib = dlopen(soname, RTLD_LOCAL | RTLD_NOW);
106 ASSERT_NE(nullptr, lib);
107 auto func = reinterpret_cast<int (*)()>(dlsym(lib, "bump"));
108 ASSERT_NE(nullptr, func);
109 return func;
110 };
111
112 static_assert(sizeof(TlsDtv) == 3 * sizeof(void*),
113 "This test assumes that the Dtv has a 3-word header");
114
115 // Initially there are 2-4 modules:
116 // - 1: test executable
117 // - 2: libc
118 // - 3: libc++ (when using a new-enough libc++)
119 // - 4: libclang_rt.hwasan (when running with HWASan)
120 size_t first_filler_modid = highest_loaded_modid() + 1;
121 ASSERT_LE(2, highest_loaded_modid());
122 ASSERT_LE(highest_loaded_modid(), 4);
123
124 // The initial DTV is an empty DTV with no generation and a size of 0.
125 TlsDtv* zero_dtv = dtv();
126 ASSERT_EQ(0u, zero_dtv->count);
127 ASSERT_EQ(nullptr, zero_dtv->next);
128 ASSERT_EQ(kTlsGenerationNone, zero_dtv->generation);
129
130 // Load a module. The DTV is still empty unless the TLS variable is accessed.
131 auto func1 = load_lib("libtest_elftls_dynamic_filler_1.so");
132 ASSERT_EQ(zero_dtv, dtv());
133 ASSERT_EQ(first_filler_modid, highest_loaded_modid());
134
135 // After accessing a TLS variable, the DTV should be initialized. It should be
136 // 8 words in size, with a 5-entry capacity.
137 ASSERT_EQ(101, func1());
138 TlsDtv* initial_dtv = dtv();
139 ASSERT_EQ(5u, dtv()->count);
140 ASSERT_EQ(zero_dtv, initial_dtv->next);
141 ASSERT_LT(0u, initial_dtv->generation);
142 ASSERT_EQ(first_filler_modid, highest_modid_in_dtv());
143 ASSERT_NE(nullptr, initial_dtv->modules[__tls_module_id_to_idx(first_filler_modid)]);
144
145 size_t current_generation = initial_dtv->generation;
146
147 // Fill the rest of the DTV up. (i.e. Ensure that exactly 5 modules with TLS
148 // segments are loaded.)
149 auto fill_entry = [&](size_t modid, const char* soname, int tls_var_value) {
150 if (highest_modid_in_dtv() == modid - 1) {
151 auto func = load_lib(soname);
152
153 // Loading the module doesn't affect the DTV yet.
154 ASSERT_EQ(initial_dtv, dtv());
155 ASSERT_EQ(modid, highest_loaded_modid());
156 ASSERT_EQ(modid - 1, highest_modid_in_dtv());
157 ASSERT_EQ(current_generation, initial_dtv->generation);
158
159 // Access the TLS variable, which will allocate it in the DTV.
160 ASSERT_EQ(tls_var_value, func());
161
162 // Verify allocation and a bumped generation.
163 ASSERT_EQ(initial_dtv, dtv());
164 ASSERT_EQ(modid, highest_modid_in_dtv());
165 ASSERT_LT(current_generation, initial_dtv->generation);
166 current_generation = initial_dtv->generation;
167 }
168 };
169
170 fill_entry(4u, "libtest_elftls_dynamic_filler_2.so", 201);
171 fill_entry(5u, "libtest_elftls_dynamic_filler_3.so", 301);
172 ASSERT_EQ(5u, highest_modid_in_dtv());
173
174 // Load module 6, which will require doubling the size of the DTV.
175 auto func4 = load_lib("libtest_elftls_dynamic_filler_4.so");
176 ASSERT_EQ(6u, highest_loaded_modid());
177 ASSERT_EQ(5u, highest_modid_in_dtv());
178 ASSERT_EQ(initial_dtv, dtv());
179
180 // Access a TLS variable from the first filler module.
181 ASSERT_EQ(102, func1());
182 ASSERT_EQ(5u, highest_modid_in_dtv());
183 #if defined(__aarch64__) || defined(__riscv)
184 // The arm64 and riscv64 TLSDESC resolver doesn't update the DTV if it is new enough for
185 // the given access.
186 ASSERT_EQ(initial_dtv, dtv());
187 ASSERT_EQ(5u, dtv()->count);
188 ASSERT_EQ(current_generation, dtv()->generation);
189 #else
190 // __tls_get_addr updates the DTV anytime the generation counter changes, but
191 // the highest modid in the DTV is still 5, because module 6 hasn't been
192 // allocated yet.
193 ASSERT_NE(initial_dtv, dtv());
194 ASSERT_EQ(13u, dtv()->count);
195 ASSERT_LT(current_generation, dtv()->generation);
196 #endif
197
198 // Accessing the TLS variable in the latest module will always expand the DTV.
199 ASSERT_EQ(401, func4());
200 TlsDtv* new_dtv = dtv();
201 ASSERT_NE(initial_dtv, new_dtv);
202 ASSERT_EQ(initial_dtv, new_dtv->next);
203 ASSERT_EQ(13u, new_dtv->count);
204 ASSERT_LT(current_generation, new_dtv->generation);
205 ASSERT_EQ(6u, highest_modid_in_dtv());
206 current_generation = new_dtv->generation;
207
208 // Load one more filler, module 7.
209 auto func5 = load_lib("libtest_elftls_dynamic_filler_5.so");
210 ASSERT_EQ(103, func1());
211 ASSERT_EQ(402, func4());
212 ASSERT_EQ(6u, highest_modid_in_dtv());
213 ASSERT_EQ(501, func5());
214 ASSERT_EQ(7u, highest_modid_in_dtv());
215
216 // Verify that no new DTV has been allocated.
217 ASSERT_EQ(new_dtv, dtv());
218 ASSERT_EQ(13u, new_dtv->count);
219 ASSERT_LT(current_generation, new_dtv->generation);
220
221 return 0;
222 }
223