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/*
* Copyright (C) 2019 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 "linker_tls.h"
#include <vector>
#include "async_safe/CHECK.h"
#include "private/ScopedRWLock.h"
#include "private/ScopedSignalBlocker.h"
#include "private/bionic_defs.h"
#include "private/bionic_elf_tls.h"
#include "private/bionic_globals.h"
#include "private/linker_native_bridge.h"
#include "linker_main.h"
#include "linker_soinfo.h"
static bool g_static_tls_finished;
static std::vector<TlsModule> g_tls_modules;
static size_t get_unused_module_index() {
for (size_t i = 0; i < g_tls_modules.size(); ++i) {
if (g_tls_modules[i].soinfo_ptr == nullptr) {
return i;
}
}
g_tls_modules.push_back({});
__libc_shared_globals()->tls_modules.module_count = g_tls_modules.size();
__libc_shared_globals()->tls_modules.module_table = g_tls_modules.data();
return g_tls_modules.size() - 1;
}
static void register_tls_module(soinfo* si, size_t static_offset) {
TlsModules& libc_modules = __libc_shared_globals()->tls_modules;
// The global TLS module table points at the std::vector of modules declared
// in this file, so acquire a write lock before modifying the std::vector.
ScopedSignalBlocker ssb;
ScopedWriteLock locker(&libc_modules.rwlock);
size_t module_idx = get_unused_module_index();
soinfo_tls* si_tls = si->get_tls();
si_tls->module_id = __tls_module_idx_to_id(module_idx);
const size_t new_generation = ++libc_modules.generation;
__libc_tls_generation_copy = new_generation;
if (libc_modules.generation_libc_so != nullptr) {
*libc_modules.generation_libc_so = new_generation;
}
g_tls_modules[module_idx] = {
.segment = si_tls->segment,
.static_offset = static_offset,
.first_generation = new_generation,
.soinfo_ptr = si,
};
}
static void unregister_tls_module(soinfo* si) {
ScopedSignalBlocker ssb;
ScopedWriteLock locker(&__libc_shared_globals()->tls_modules.rwlock);
soinfo_tls* si_tls = si->get_tls();
TlsModule& mod = g_tls_modules[__tls_module_id_to_idx(si_tls->module_id)];
CHECK(mod.static_offset == SIZE_MAX);
CHECK(mod.soinfo_ptr == si);
mod = {};
si_tls->module_id = kTlsUninitializedModuleId;
}
// The reference is valid until a TLS module is registered or unregistered.
const TlsModule& get_tls_module(size_t module_id) {
size_t module_idx = __tls_module_id_to_idx(module_id);
CHECK(module_idx < g_tls_modules.size());
return g_tls_modules[module_idx];
}
__BIONIC_WEAK_FOR_NATIVE_BRIDGE
extern "C" void __linker_reserve_bionic_tls_in_static_tls() {
__libc_shared_globals()->static_tls_layout.reserve_bionic_tls();
}
void linker_setup_exe_static_tls(const char* progname) {
soinfo* somain = solist_get_somain();
StaticTlsLayout& layout = __libc_shared_globals()->static_tls_layout;
if (somain->get_tls() == nullptr) {
layout.reserve_exe_segment_and_tcb(nullptr, progname);
} else {
register_tls_module(somain, layout.reserve_exe_segment_and_tcb(&somain->get_tls()->segment, progname));
}
// The pthread key data is located at the very front of bionic_tls. As a
// temporary workaround, allocate bionic_tls just after the thread pointer so
// Golang can find its pthread key, as long as the executable's TLS segment is
// small enough. Specifically, Golang scans forward 384 words from the TP on
// ARM.
// - http://b/118381796
// - https://github.com/golang/go/issues/29674
__linker_reserve_bionic_tls_in_static_tls();
}
void linker_finalize_static_tls() {
g_static_tls_finished = true;
__libc_shared_globals()->static_tls_layout.finish_layout();
TlsModules& modules = __libc_shared_globals()->tls_modules;
modules.static_module_count = modules.module_count;
}
void register_soinfo_tls(soinfo* si) {
soinfo_tls* si_tls = si->get_tls();
if (si_tls == nullptr || si_tls->module_id != kTlsUninitializedModuleId) {
return;
}
size_t static_offset = SIZE_MAX;
if (!g_static_tls_finished) {
StaticTlsLayout& layout = __libc_shared_globals()->static_tls_layout;
static_offset = layout.reserve_solib_segment(si_tls->segment);
}
register_tls_module(si, static_offset);
}
void unregister_soinfo_tls(soinfo* si) {
soinfo_tls* si_tls = si->get_tls();
if (si_tls == nullptr || si_tls->module_id == kTlsUninitializedModuleId) {
return;
}
return unregister_tls_module(si);
}
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