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be509b3387
Linux doesn't allocate the whole stack right away, and the kernel has its own stack-guard mechanism to fault when growing too close to an existing mapping. If we map our own guard, then the kernel starts enforcing a rather large gap above that, rendering much of the possible stack space useless. Instead, we'll just note where we expect rlimit to start faulting, so our handler can report "stack overflow", and trust that the kernel's own stack guard will work. Fixes #43052.
391 lines
14 KiB
Rust
391 lines
14 KiB
Rust
// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use alloc::boxed::FnBox;
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use cmp;
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use ffi::CStr;
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use io;
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use libc;
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use mem;
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use ptr;
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use sys::os;
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use time::Duration;
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use sys_common::thread::*;
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pub struct Thread {
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id: libc::pthread_t,
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}
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// Some platforms may have pthread_t as a pointer in which case we still want
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// a thread to be Send/Sync
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unsafe impl Send for Thread {}
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unsafe impl Sync for Thread {}
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// The pthread_attr_setstacksize symbol doesn't exist in the emscripten libc,
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// so we have to not link to it to satisfy emcc's ERROR_ON_UNDEFINED_SYMBOLS.
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#[cfg(not(target_os = "emscripten"))]
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unsafe fn pthread_attr_setstacksize(attr: *mut libc::pthread_attr_t,
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stack_size: libc::size_t) -> libc::c_int {
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libc::pthread_attr_setstacksize(attr, stack_size)
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}
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#[cfg(target_os = "emscripten")]
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unsafe fn pthread_attr_setstacksize(_attr: *mut libc::pthread_attr_t,
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_stack_size: libc::size_t) -> libc::c_int {
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panic!()
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}
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impl Thread {
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pub unsafe fn new<'a>(stack: usize, p: Box<FnBox() + 'a>)
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-> io::Result<Thread> {
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let p = box p;
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let mut native: libc::pthread_t = mem::zeroed();
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let mut attr: libc::pthread_attr_t = mem::zeroed();
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assert_eq!(libc::pthread_attr_init(&mut attr), 0);
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let stack_size = cmp::max(stack, min_stack_size(&attr));
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match pthread_attr_setstacksize(&mut attr,
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stack_size) {
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0 => {}
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n => {
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assert_eq!(n, libc::EINVAL);
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// EINVAL means |stack_size| is either too small or not a
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// multiple of the system page size. Because it's definitely
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// >= PTHREAD_STACK_MIN, it must be an alignment issue.
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// Round up to the nearest page and try again.
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let page_size = os::page_size();
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let stack_size = (stack_size + page_size - 1) &
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(-(page_size as isize - 1) as usize - 1);
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assert_eq!(libc::pthread_attr_setstacksize(&mut attr,
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stack_size), 0);
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}
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};
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let ret = libc::pthread_create(&mut native, &attr, thread_start,
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&*p as *const _ as *mut _);
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assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
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return if ret != 0 {
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Err(io::Error::from_raw_os_error(ret))
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} else {
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mem::forget(p); // ownership passed to pthread_create
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Ok(Thread { id: native })
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};
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extern fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void {
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unsafe { start_thread(main); }
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ptr::null_mut()
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}
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}
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pub fn yield_now() {
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let ret = unsafe { libc::sched_yield() };
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debug_assert_eq!(ret, 0);
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}
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#[cfg(any(target_os = "linux",
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target_os = "android"))]
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pub fn set_name(name: &CStr) {
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const PR_SET_NAME: libc::c_int = 15;
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// pthread wrapper only appeared in glibc 2.12, so we use syscall
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// directly.
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unsafe {
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libc::prctl(PR_SET_NAME, name.as_ptr() as libc::c_ulong, 0, 0, 0);
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}
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}
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#[cfg(any(target_os = "freebsd",
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target_os = "dragonfly",
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target_os = "bitrig",
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target_os = "openbsd"))]
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pub fn set_name(name: &CStr) {
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unsafe {
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libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr());
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}
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}
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#[cfg(any(target_os = "macos", target_os = "ios"))]
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pub fn set_name(name: &CStr) {
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unsafe {
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libc::pthread_setname_np(name.as_ptr());
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}
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}
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#[cfg(target_os = "netbsd")]
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pub fn set_name(name: &CStr) {
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use ffi::CString;
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let cname = CString::new(&b"%s"[..]).unwrap();
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unsafe {
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libc::pthread_setname_np(libc::pthread_self(), cname.as_ptr(),
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name.as_ptr() as *mut libc::c_void);
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}
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}
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#[cfg(any(target_env = "newlib",
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target_os = "solaris",
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target_os = "haiku",
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target_os = "emscripten"))]
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pub fn set_name(_name: &CStr) {
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// Newlib, Illumos, Haiku, and Emscripten have no way to set a thread name.
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}
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#[cfg(target_os = "fuchsia")]
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pub fn set_name(_name: &CStr) {
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// FIXME: determine whether Fuchsia has a way to set a thread name.
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}
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pub fn sleep(dur: Duration) {
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let mut secs = dur.as_secs();
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let mut nsecs = dur.subsec_nanos() as libc::c_long;
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// If we're awoken with a signal then the return value will be -1 and
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// nanosleep will fill in `ts` with the remaining time.
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unsafe {
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while secs > 0 || nsecs > 0 {
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let mut ts = libc::timespec {
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tv_sec: cmp::min(libc::time_t::max_value() as u64, secs) as libc::time_t,
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tv_nsec: nsecs,
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};
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secs -= ts.tv_sec as u64;
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if libc::nanosleep(&ts, &mut ts) == -1 {
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assert_eq!(os::errno(), libc::EINTR);
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secs += ts.tv_sec as u64;
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nsecs = ts.tv_nsec;
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} else {
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nsecs = 0;
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}
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}
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}
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}
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pub fn join(self) {
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unsafe {
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let ret = libc::pthread_join(self.id, ptr::null_mut());
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mem::forget(self);
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debug_assert_eq!(ret, 0);
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}
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}
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pub fn id(&self) -> libc::pthread_t { self.id }
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pub fn into_id(self) -> libc::pthread_t {
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let id = self.id;
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mem::forget(self);
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id
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}
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}
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impl Drop for Thread {
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fn drop(&mut self) {
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let ret = unsafe { libc::pthread_detach(self.id) };
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debug_assert_eq!(ret, 0);
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}
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}
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#[cfg(all(not(all(target_os = "linux", not(target_env = "musl"))),
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not(target_os = "freebsd"),
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not(target_os = "macos"),
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not(target_os = "bitrig"),
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not(all(target_os = "netbsd", not(target_vendor = "rumprun"))),
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not(target_os = "openbsd"),
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not(target_os = "solaris")))]
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#[cfg_attr(test, allow(dead_code))]
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pub mod guard {
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pub unsafe fn current() -> Option<usize> { None }
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pub unsafe fn init() -> Option<usize> { None }
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}
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#[cfg(any(all(target_os = "linux", not(target_env = "musl")),
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target_os = "freebsd",
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target_os = "macos",
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target_os = "bitrig",
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all(target_os = "netbsd", not(target_vendor = "rumprun")),
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target_os = "openbsd",
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target_os = "solaris"))]
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#[cfg_attr(test, allow(dead_code))]
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pub mod guard {
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use libc;
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use libc::mmap;
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use libc::{PROT_NONE, MAP_PRIVATE, MAP_ANON, MAP_FAILED, MAP_FIXED};
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use sys::os;
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#[cfg(any(target_os = "macos",
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target_os = "bitrig",
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target_os = "openbsd",
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target_os = "solaris"))]
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unsafe fn get_stack_start() -> Option<*mut libc::c_void> {
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current().map(|s| s as *mut libc::c_void)
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}
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#[cfg(any(target_os = "android", target_os = "freebsd",
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target_os = "linux", target_os = "netbsd"))]
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unsafe fn get_stack_start() -> Option<*mut libc::c_void> {
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let mut ret = None;
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let mut attr: libc::pthread_attr_t = ::mem::zeroed();
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assert_eq!(libc::pthread_attr_init(&mut attr), 0);
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#[cfg(target_os = "freebsd")]
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let e = libc::pthread_attr_get_np(libc::pthread_self(), &mut attr);
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#[cfg(not(target_os = "freebsd"))]
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let e = libc::pthread_getattr_np(libc::pthread_self(), &mut attr);
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if e == 0 {
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let mut stackaddr = ::ptr::null_mut();
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let mut stacksize = 0;
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assert_eq!(libc::pthread_attr_getstack(&attr, &mut stackaddr,
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&mut stacksize), 0);
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ret = Some(stackaddr);
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}
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assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
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ret
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}
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pub unsafe fn init() -> Option<usize> {
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let psize = os::page_size();
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let mut stackaddr = match get_stack_start() {
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Some(addr) => addr,
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None => return None,
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};
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// Ensure stackaddr is page aligned! A parent process might
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// have reset RLIMIT_STACK to be non-page aligned. The
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// pthread_attr_getstack() reports the usable stack area
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// stackaddr < stackaddr + stacksize, so if stackaddr is not
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// page-aligned, calculate the fix such that stackaddr <
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// new_page_aligned_stackaddr < stackaddr + stacksize
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let remainder = (stackaddr as usize) % psize;
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if remainder != 0 {
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stackaddr = ((stackaddr as usize) + psize - remainder)
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as *mut libc::c_void;
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}
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if cfg!(target_os = "linux") {
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// Linux doesn't allocate the whole stack right away, and
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// the kernel has its own stack-guard mechanism to fault
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// when growing too close to an existing mapping. If we map
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// our own guard, then the kernel starts enforcing a rather
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// large gap above that, rendering much of the possible
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// stack space useless. See #43052.
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//
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// Instead, we'll just note where we expect rlimit to start
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// faulting, so our handler can report "stack overflow", and
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// trust that the kernel's own stack guard will work.
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Some(stackaddr as usize)
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} else {
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// Reallocate the last page of the stack.
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// This ensures SIGBUS will be raised on
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// stack overflow.
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let result = mmap(stackaddr, psize, PROT_NONE,
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MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0);
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if result != stackaddr || result == MAP_FAILED {
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panic!("failed to allocate a guard page");
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}
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let offset = if cfg!(target_os = "freebsd") {
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2
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} else {
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1
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};
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Some(stackaddr as usize + offset * psize)
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}
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}
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#[cfg(target_os = "solaris")]
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pub unsafe fn current() -> Option<usize> {
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let mut current_stack: libc::stack_t = ::mem::zeroed();
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assert_eq!(libc::stack_getbounds(&mut current_stack), 0);
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Some(current_stack.ss_sp as usize)
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}
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#[cfg(target_os = "macos")]
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pub unsafe fn current() -> Option<usize> {
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Some((libc::pthread_get_stackaddr_np(libc::pthread_self()) as usize -
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libc::pthread_get_stacksize_np(libc::pthread_self())))
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}
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#[cfg(any(target_os = "openbsd", target_os = "bitrig"))]
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pub unsafe fn current() -> Option<usize> {
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let mut current_stack: libc::stack_t = ::mem::zeroed();
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assert_eq!(libc::pthread_stackseg_np(libc::pthread_self(),
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&mut current_stack), 0);
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let extra = if cfg!(target_os = "bitrig") {3} else {1} * os::page_size();
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Some(if libc::pthread_main_np() == 1 {
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// main thread
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current_stack.ss_sp as usize - current_stack.ss_size + extra
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} else {
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// new thread
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current_stack.ss_sp as usize - current_stack.ss_size
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})
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}
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#[cfg(any(target_os = "android", target_os = "freebsd",
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target_os = "linux", target_os = "netbsd"))]
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pub unsafe fn current() -> Option<usize> {
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let mut ret = None;
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let mut attr: libc::pthread_attr_t = ::mem::zeroed();
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assert_eq!(libc::pthread_attr_init(&mut attr), 0);
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#[cfg(target_os = "freebsd")]
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let e = libc::pthread_attr_get_np(libc::pthread_self(), &mut attr);
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#[cfg(not(target_os = "freebsd"))]
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let e = libc::pthread_getattr_np(libc::pthread_self(), &mut attr);
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if e == 0 {
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let mut guardsize = 0;
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assert_eq!(libc::pthread_attr_getguardsize(&attr, &mut guardsize), 0);
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if guardsize == 0 {
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panic!("there is no guard page");
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}
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let mut stackaddr = ::ptr::null_mut();
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let mut size = 0;
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assert_eq!(libc::pthread_attr_getstack(&attr, &mut stackaddr,
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&mut size), 0);
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ret = if cfg!(target_os = "freebsd") {
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Some(stackaddr as usize - guardsize)
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} else if cfg!(target_os = "netbsd") {
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Some(stackaddr as usize)
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} else {
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Some(stackaddr as usize + guardsize)
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};
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}
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assert_eq!(libc::pthread_attr_destroy(&mut attr), 0);
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ret
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}
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}
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// glibc >= 2.15 has a __pthread_get_minstack() function that returns
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// PTHREAD_STACK_MIN plus however many bytes are needed for thread-local
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// storage. We need that information to avoid blowing up when a small stack
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// is created in an application with big thread-local storage requirements.
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// See #6233 for rationale and details.
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#[cfg(target_os = "linux")]
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#[allow(deprecated)]
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fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize {
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weak!(fn __pthread_get_minstack(*const libc::pthread_attr_t) -> libc::size_t);
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match __pthread_get_minstack.get() {
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None => libc::PTHREAD_STACK_MIN,
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Some(f) => unsafe { f(attr) },
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}
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}
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// No point in looking up __pthread_get_minstack() on non-glibc
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// platforms.
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#[cfg(all(not(target_os = "linux"),
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not(target_os = "netbsd")))]
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fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
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libc::PTHREAD_STACK_MIN
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}
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#[cfg(target_os = "netbsd")]
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fn min_stack_size(_: *const libc::pthread_attr_t) -> usize {
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2048 // just a guess
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}
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