================
@@ -159,88 +28,8 @@ extern "C" void _start() {
// compilers can generate code assuming the alignment as required by the ABI.
// If the stack pointers as setup by the OS are already aligned, then the
// following code is a NOP.
- __asm__ __volatile__("andq $0xfffffffffffffff0, %rsp\n\t");
- __asm__ __volatile__("andq $0xfffffffffffffff0, %rbp\n\t");
-
- auto tid = LIBC_NAMESPACE::syscall_impl<long>(SYS_gettid);
- if (tid <= 0)
- LIBC_NAMESPACE::syscall_impl<long>(SYS_exit, 1);
- LIBC_NAMESPACE::main_thread_attrib.tid = static_cast<int>(tid);
-
- // After the argv array, is a 8-byte long NULL value before the array of env
- // values. The end of the env values is marked by another 8-byte long NULL
- // value. We step over it (the "+ 1" below) to get to the env values.
- uint64_t *env_ptr = app.args->argv + app.args->argc + 1;
- uint64_t *env_end_marker = env_ptr;
- app.env_ptr = env_ptr;
- while (*env_end_marker)
- ++env_end_marker;
-
- // Initialize the POSIX global declared in unistd.h
- environ = reinterpret_cast<char **>(env_ptr);
-
- // After the env array, is the aux-vector. The end of the aux-vector is
- // denoted by an AT_NULL entry.
- Elf64_Phdr *program_hdr_table = nullptr;
- uintptr_t program_hdr_count = 0;
- app.auxv_ptr = reinterpret_cast<AuxEntry *>(env_end_marker + 1);
- for (auto *aux_entry = app.auxv_ptr; aux_entry->id != AT_NULL; ++aux_entry) {
- switch (aux_entry->id) {
- case AT_PHDR:
- program_hdr_table = reinterpret_cast<Elf64_Phdr *>(aux_entry->value);
- break;
- case AT_PHNUM:
- program_hdr_count = aux_entry->value;
- break;
- case AT_PAGESZ:
- app.page_size = aux_entry->value;
- break;
- default:
- break; // TODO: Read other useful entries from the aux vector.
- }
- }
-
- app.tls.size = 0;
- for (uintptr_t i = 0; i < program_hdr_count; ++i) {
- Elf64_Phdr *phdr = program_hdr_table + i;
- if (phdr->p_type != PT_TLS)
- continue;
- // TODO: p_vaddr value has to be adjusted for static-pie executables.
- app.tls.address = phdr->p_vaddr;
- app.tls.size = phdr->p_memsz;
- app.tls.init_size = phdr->p_filesz;
- app.tls.align = phdr->p_align;
- }
-
- // This descriptor has to be static since its cleanup function cannot
- // capture the context.
- static LIBC_NAMESPACE::TLSDescriptor tls;
- LIBC_NAMESPACE::init_tls(tls);
- if (tls.size != 0 && !LIBC_NAMESPACE::set_thread_ptr(tls.tp))
- LIBC_NAMESPACE::syscall_impl<long>(SYS_exit, 1);
-
- LIBC_NAMESPACE::self.attrib = &LIBC_NAMESPACE::main_thread_attrib;
- LIBC_NAMESPACE::main_thread_attrib.atexit_callback_mgr =
- LIBC_NAMESPACE::internal::get_thread_atexit_callback_mgr();
- // We register the cleanup_tls function to be the last atexit callback to be
- // invoked. It will tear down the TLS. Other callbacks may depend on TLS (such
- // as the stack protector canary).
- LIBC_NAMESPACE::atexit(
- []() { LIBC_NAMESPACE::cleanup_tls(tls.tp, tls.size); });
- // We want the fini array callbacks to be run after other atexit
- // callbacks are run. So, we register them before running the init
- // array callbacks as they can potentially register their own atexit
- // callbacks.
- LIBC_NAMESPACE::atexit(&LIBC_NAMESPACE::call_fini_array_callbacks);
-
- LIBC_NAMESPACE::call_init_array_callbacks(
- static_cast<int>(app.args->argc),
- reinterpret_cast<char **>(app.args->argv),
- reinterpret_cast<char **>(env_ptr));
-
- int retval = main(static_cast<int>(app.args->argc),
- reinterpret_cast<char **>(app.args->argv),
- reinterpret_cast<char **>(env_ptr));
+ LIBC_INLINE_ASM("andq $0xfffffffffffffff0, %rsp\n\t");
----------------
michaelrj-google wrote:
it's probably best not to use `LIBC_INLINE_ASM` here since it's likely we'll be removing that macro soon, see https://github.com/llvm/llvm-project/issues/75956 for more info.
https://github.com/llvm/llvm-project/pull/76092