msan-dynamic-tls

.msan-dynamic-tls-example

//

CMakeLists.txt

cmake_minimum_required(VERSION 3.23)
project(Test)

set(CMAKE_VERBOSE_MAKEFILE ON)
set(CMAKE_C_COMPILER clang-15)
set(CMAKE_CXX_COMPILER clang++-15)

add_compile_options(-fsanitize=memory -fsanitize-memory-track-origins=2)
add_link_options(-fsanitize=memory)
# add_compile_options(-stdlib=libc++)
# add_link_options(-stdlib=libc++ -L/home/ccat3z/Documents/moqi/llvm/llvm-project-llvmorg-15.0.7/build/lib -Wl,-rpath,/home/ccat3z/Documents/moqi/llvm/llvm-project-llvmorg-15.0.7/build/lib)

add_library(one SHARED one.cpp)
add_executable(main main.cpp)

# NOTE: Dynamic tls is not work for msan: use-of-uninitialized-value
target_compile_options(one PRIVATE -ftls-model=local-dynamic)
# target_compile_options(one PRIVATE -ftls-model=initial-exec)

# For dynamic tls model, TLS_SIZE can be value.
# For static tls model. If TLS_SIZE is too large, you need to increase the amount
# of surplus static TLS, which requires glibc >= 2.33:
#   export GLIBC_TUNABLES=glibc.rtld.nns=10
# Otherwise, dlopen will failed with `cannot allocate memory in static TLS block`
# See also:
#   * https://maskray.me/blog/2021-02-14-all-about-thread-local-storage
#   * https://www.gnu.org/software/libc/manual/html_node/Dynamic-Linking-Tunables.html#index-glibc_002ertld_002enns

target_compile_definitions(one PRIVATE TLS_SIZE=1600)

main.cpp

#include <iostream>
#include <dlfcn.h>

int main(int argc, const char *argv[]) {
    auto handle = dlopen("./build/libone.so", RTLD_LAZY);
    if (!handle) {
        std::cerr << dlerror() << std::endl;
        return 1;
    }
    void (*thread_data)();
    thread_data = reinterpret_cast<decltype(thread_data)>(dlsym(handle, "thread_data"));
    thread_data();
    return 0;
}

one.cpp

#include <iostream>

namespace {
struct ThreadData {
    ThreadData() {
        std::cerr << "tls init in lib" << std::endl;
    }
    char data[TLS_SIZE] = "hello";

    void f() {
        std::cerr << data << std::endl;
    }

    static void g() {
        static thread_local ThreadData t;
        t.f();
    }
};
}

extern "C" {
    void thread_data() {
        ThreadData::g();
    }
}