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DynamicLoader: Fix TLS memory initialization

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I was reading the TLS data before performing relocations so any TLS
variables pointing to relocated objects would not get the correct data
This commit is contained in:
Bananymous
2026-07-05 12:24:55 +03:00
parent 9fd015a84e
commit ea4e016b1e
1 changed files with 62 additions and 54 deletions
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116
userspace/programs/DynamicLoader/main.cpp
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@@ -430,9 +430,6 @@ static void handle_tls_relocation(const LoadedElf& elf, const RelocT& reloc)
if (symbol_elf == nullptr)
print_error_and_exit("i don't think this is supposed to happen 2", 0);
if (symbol_elf->tls_addr == nullptr)
print_error_and_exit("i don't think this is supposed to happen 3", 0);
#if defined(__x86_64__)
switch (ELF64_R_TYPE(reloc.r_info))
{
@@ -1160,6 +1157,7 @@ static LoadedElf& load_elf(const char* path, int fd)
case PT_GNU_RELRO:
break;
case PT_TLS:
program_header.p_vaddr += base;
elf.tls_header = program_header;
break;
case PT_LOAD:
@@ -1218,7 +1216,7 @@ struct MasterTLS
size_t module_count;
};
static MasterTLS initialize_master_tls()
static MasterTLS initialize_tls_stage1()
{
constexpr auto round =
[](size_t a, size_t b) -> size_t
@@ -1245,28 +1243,6 @@ static MasterTLS initialize_master_tls()
module_count++;
}
{
const sys_mmap_t mmap_args {
.addr = nullptr,
.len = sizeof(_dynamic_tls_t) + s_max_loaded_files * sizeof(_dynamic_tls_entry_t),
.prot = PROT_READ | PROT_WRITE,
.flags = MAP_ANONYMOUS | MAP_PRIVATE,
.fildes = -1,
.off = 0,
};
const auto ret = syscall(SYS_MMAP, &mmap_args);
if (ret < 0)
print_error_and_exit("failed to allocate dynamic TLS", ret);
s_dynamic_tls = reinterpret_cast<_dynamic_tls_t*>(ret);
*s_dynamic_tls = {
.lock = 0,
.entry_count = 0,
.entries = reinterpret_cast<_dynamic_tls_entry_t*>(s_dynamic_tls + 1),
};
}
if (module_count == 0)
return { .addr = nullptr, .size = 0, .module_count = 0 };
@@ -1300,19 +1276,8 @@ static MasterTLS initialize_master_tls()
tls_offset = round(tls_offset + tls_header.p_memsz, tls_header.p_align);
uint8_t* tls_buffer = master_tls_addr + master_tls_size - tls_offset;
if (tls_header.p_filesz > 0)
{
const int fd = s_loaded_files[i].fd;
if (auto ret = syscall(SYS_PREAD, fd, tls_buffer, tls_header.p_filesz, tls_header.p_offset); ret != static_cast<long>(tls_header.p_filesz))
print_error_and_exit("failed to read TLS data", ret);
}
memset(tls_buffer + tls_header.p_filesz, 0, tls_header.p_memsz - tls_header.p_filesz);
auto& elf = s_loaded_files[i];
elf.tls_addr = tls_buffer;
elf.tls_addr = master_tls_addr + master_tls_size - tls_offset;
elf.tls_module = s_tls_module++;
elf.tls_offset = tls_offset;
}
@@ -1324,8 +1289,49 @@ static MasterTLS initialize_master_tls()
};
}
static void initialize_tls(MasterTLS master_tls)
static void allocate_dynamic_tls()
{
const sys_mmap_t mmap_args {
.addr = nullptr,
.len = sizeof(_dynamic_tls_t) + s_max_loaded_files * sizeof(_dynamic_tls_entry_t),
.prot = PROT_READ | PROT_WRITE,
.flags = MAP_ANONYMOUS | MAP_PRIVATE,
.fildes = -1,
.off = 0,
};
const auto ret = syscall(SYS_MMAP, &mmap_args);
if (ret < 0)
print_error_and_exit("failed to allocate dynamic TLS", ret);
s_dynamic_tls = reinterpret_cast<_dynamic_tls_t*>(ret);
*s_dynamic_tls = {
.lock = 0,
.entry_count = 0,
.entries = reinterpret_cast<_dynamic_tls_entry_t*>(s_dynamic_tls + 1),
};
}
static void initialize_tls_memory()
{
for (size_t i = 0; i < s_loaded_file_count; i++)
{
const auto& tls_header = s_loaded_files[i].tls_header;
if (tls_header.p_type != PT_TLS)
continue;
auto& elf = s_loaded_files[i];
memcpy(elf.tls_addr, reinterpret_cast<void*>(tls_header.p_vaddr), tls_header.p_filesz);
memset(elf.tls_addr + tls_header.p_filesz, 0, tls_header.p_memsz - tls_header.p_filesz);
}
}
static void initialize_tls_stage2(MasterTLS master_tls)
{
allocate_dynamic_tls();
initialize_tls_memory();
const size_t tls_size = master_tls.size + sizeof(uthread);
uint8_t* tls_addr;
@@ -1498,14 +1504,6 @@ static void register_fini_funcs(LoadedElf& elf, bool is_main_elf)
static void load_dynamic_tls(LoadedElf& elf)
{
if (elf.tls_header.p_type != PT_TLS)
return;
if (elf.tls_module != 0)
print_error_and_exit("TLS module already loaded??", 0);
elf.tls_module = s_tls_module++;
elf.tls_offset = 0;
{
const sys_mmap_t mmap_args {
.addr = nullptr,
@@ -1519,11 +1517,10 @@ static void load_dynamic_tls(LoadedElf& elf)
const auto ret = syscall(SYS_MMAP, &mmap_args);
if (ret < 0)
print_error_and_exit("failed to allocate dynamic TLS", ret);
elf.tls_addr = reinterpret_cast<uint8_t*>(ret);
elf.tls_addr = reinterpret_cast<uint8_t*>(ret);
memcpy(elf.tls_addr, reinterpret_cast<void*>(elf.tls_header.p_vaddr), elf.tls_header.p_filesz);
memset(elf.tls_addr + elf.tls_header.p_filesz, 0, elf.tls_header.p_memsz - elf.tls_header.p_filesz);
if (const auto ret = syscall(SYS_PREAD, elf.fd, elf.tls_addr, elf.tls_header.p_filesz, elf.tls_header.p_offset); ret < static_cast<long>(elf.tls_header.p_filesz))
print_error_and_exit("failed to read TLS data", 0);
}
int expected = 0;
@@ -1599,10 +1596,19 @@ void* __dlopen(const char* file, int mode)
if (!elf.is_relocating && !elf.is_calling_init)
{
for (size_t i = old_loaded_count; i < s_loaded_file_count; i++)
load_dynamic_tls(s_loaded_files[i]);
{
if (s_loaded_files[i].tls_header.p_type != PT_TLS)
continue;
s_loaded_files[i].tls_module = s_tls_module++;
s_loaded_files[i].tls_offset = 0;
}
relocate_elf(elf, lazy);
for (size_t i = old_loaded_count; i < s_loaded_file_count; i++)
if (s_loaded_files[i].tls_header.p_type == PT_TLS)
load_dynamic_tls(s_loaded_files[i]);
call_init_funcs(elf, false);
register_fini_funcs(elf, false);
syscall(SYS_CLOSE, elf.fd);
@@ -1781,7 +1787,8 @@ uintptr_t _entry(int argc, char* argv[], char* envp[])
auto& elf = load_elf(canonical, execfd);
fini_random();
const auto master_tls = initialize_master_tls();
const auto master_tls = initialize_tls_stage1();
relocate_elf(elf, true);
// do copy relocations
@@ -1792,7 +1799,8 @@ uintptr_t _entry(int argc, char* argv[], char* envp[])
for (size_t i = 0; i < elf.relasz / elf.relaent; i++)
handle_copy_relocation(elf, *reinterpret_cast<ElfNativeRelocationA*>(elf.rela + i * elf.relaent));
initialize_tls(master_tls);
initialize_tls_stage2(master_tls);
initialize_environ(envp);
call_init_funcs(elf, true);
register_fini_funcs(elf, true);