diff options
Diffstat (limited to 'library/std/src/sys/unix/thread.rs')
| -rw-r--r-- | library/std/src/sys/unix/thread.rs | 465 |
1 files changed, 465 insertions, 0 deletions
diff --git a/library/std/src/sys/unix/thread.rs b/library/std/src/sys/unix/thread.rs new file mode 100644 index 00000000000..c1bda6b430e --- /dev/null +++ b/library/std/src/sys/unix/thread.rs @@ -0,0 +1,465 @@ +use crate::cmp; +use crate::ffi::CStr; +use crate::io; +use crate::mem; +use crate::ptr; +use crate::sys::{os, stack_overflow}; +use crate::time::Duration; + +#[cfg(not(target_os = "l4re"))] +pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024; +#[cfg(target_os = "l4re")] +pub const DEFAULT_MIN_STACK_SIZE: usize = 1024 * 1024; + +pub struct Thread { + id: libc::pthread_t, +} + +// Some platforms may have pthread_t as a pointer in which case we still want +// a thread to be Send/Sync +unsafe impl Send for Thread {} +unsafe impl Sync for Thread {} + +// The pthread_attr_setstacksize symbol doesn't exist in the emscripten libc, +// so we have to not link to it to satisfy emcc's ERROR_ON_UNDEFINED_SYMBOLS. +#[cfg(not(target_os = "emscripten"))] +unsafe fn pthread_attr_setstacksize( + attr: *mut libc::pthread_attr_t, + stack_size: libc::size_t, +) -> libc::c_int { + libc::pthread_attr_setstacksize(attr, stack_size) +} + +#[cfg(target_os = "emscripten")] +unsafe fn pthread_attr_setstacksize( + _attr: *mut libc::pthread_attr_t, + _stack_size: libc::size_t, +) -> libc::c_int { + panic!() +} + +impl Thread { + // unsafe: see thread::Builder::spawn_unchecked for safety requirements + pub unsafe fn new(stack: usize, p: Box<dyn FnOnce()>) -> io::Result<Thread> { + let p = Box::into_raw(box p); + let mut native: libc::pthread_t = mem::zeroed(); + let mut attr: libc::pthread_attr_t = mem::zeroed(); + assert_eq!(libc::pthread_attr_init(&mut attr), 0); + + let stack_size = cmp::max(stack, min_stack_size(&attr)); + + match pthread_attr_setstacksize(&mut attr, stack_size) { + 0 => {} + n => { + assert_eq!(n, libc::EINVAL); + // EINVAL means |stack_size| is either too small or not a + // multiple of the system page size. Because it's definitely + // >= PTHREAD_STACK_MIN, it must be an alignment issue. + // Round up to the nearest page and try again. + let page_size = os::page_size(); + let stack_size = + (stack_size + page_size - 1) & (-(page_size as isize - 1) as usize - 1); + assert_eq!(libc::pthread_attr_setstacksize(&mut attr, stack_size), 0); + } + }; + + let ret = libc::pthread_create(&mut native, &attr, thread_start, p as *mut _); + // Note: if the thread creation fails and this assert fails, then p will + // be leaked. However, an alternative design could cause double-free + // which is clearly worse. + assert_eq!(libc::pthread_attr_destroy(&mut attr), 0); + + return if ret != 0 { + // The thread failed to start and as a result p was not consumed. Therefore, it is + // safe to reconstruct the box so that it gets deallocated. + drop(Box::from_raw(p)); + Err(io::Error::from_raw_os_error(ret)) + } else { + Ok(Thread { id: native }) + }; + + extern "C" fn thread_start(main: *mut libc::c_void) -> *mut libc::c_void { + unsafe { + // Next, set up our stack overflow handler which may get triggered if we run + // out of stack. + let _handler = stack_overflow::Handler::new(); + // Finally, let's run some code. + Box::from_raw(main as *mut Box<dyn FnOnce()>)(); + } + ptr::null_mut() + } + } + + pub fn yield_now() { + let ret = unsafe { libc::sched_yield() }; + debug_assert_eq!(ret, 0); + } + + #[cfg(any(target_os = "linux", target_os = "android"))] + pub fn set_name(name: &CStr) { + const PR_SET_NAME: libc::c_int = 15; + // pthread wrapper only appeared in glibc 2.12, so we use syscall + // directly. + unsafe { + libc::prctl(PR_SET_NAME, name.as_ptr() as libc::c_ulong, 0, 0, 0); + } + } + + #[cfg(any(target_os = "freebsd", target_os = "dragonfly", target_os = "openbsd"))] + pub fn set_name(name: &CStr) { + unsafe { + libc::pthread_set_name_np(libc::pthread_self(), name.as_ptr()); + } + } + + #[cfg(any(target_os = "macos", target_os = "ios"))] + pub fn set_name(name: &CStr) { + unsafe { + libc::pthread_setname_np(name.as_ptr()); + } + } + + #[cfg(target_os = "netbsd")] + pub fn set_name(name: &CStr) { + use crate::ffi::CString; + let cname = CString::new(&b"%s"[..]).unwrap(); + unsafe { + libc::pthread_setname_np( + libc::pthread_self(), + cname.as_ptr(), + name.as_ptr() as *mut libc::c_void, + ); + } + } + + #[cfg(any(target_os = "solaris", target_os = "illumos"))] + pub fn set_name(name: &CStr) { + weak! { + fn pthread_setname_np( + libc::pthread_t, *const libc::c_char + ) -> libc::c_int + } + + if let Some(f) = pthread_setname_np.get() { + unsafe { + f(libc::pthread_self(), name.as_ptr()); + } + } + } + + #[cfg(any( + target_env = "newlib", + target_os = "haiku", + target_os = "l4re", + target_os = "emscripten", + target_os = "redox" + ))] + pub fn set_name(_name: &CStr) { + // Newlib, Haiku, and Emscripten have no way to set a thread name. + } + #[cfg(target_os = "fuchsia")] + pub fn set_name(_name: &CStr) { + // FIXME: determine whether Fuchsia has a way to set a thread name. + } + + pub fn sleep(dur: Duration) { + let mut secs = dur.as_secs(); + let mut nsecs = dur.subsec_nanos() as _; + + // If we're awoken with a signal then the return value will be -1 and + // nanosleep will fill in `ts` with the remaining time. + unsafe { + while secs > 0 || nsecs > 0 { + let mut ts = libc::timespec { + tv_sec: cmp::min(libc::time_t::MAX as u64, secs) as libc::time_t, + tv_nsec: nsecs, + }; + secs -= ts.tv_sec as u64; + if libc::nanosleep(&ts, &mut ts) == -1 { + assert_eq!(os::errno(), libc::EINTR); + secs += ts.tv_sec as u64; + nsecs = ts.tv_nsec; + } else { + nsecs = 0; + } + } + } + } + + pub fn join(self) { + unsafe { + let ret = libc::pthread_join(self.id, ptr::null_mut()); + mem::forget(self); + assert!(ret == 0, "failed to join thread: {}", io::Error::from_raw_os_error(ret)); + } + } + + pub fn id(&self) -> libc::pthread_t { + self.id + } + + pub fn into_id(self) -> libc::pthread_t { + let id = self.id; + mem::forget(self); + id + } +} + +impl Drop for Thread { + fn drop(&mut self) { + let ret = unsafe { libc::pthread_detach(self.id) }; + debug_assert_eq!(ret, 0); + } +} + +#[cfg(all( + not(all(target_os = "linux", not(target_env = "musl"))), + not(target_os = "freebsd"), + not(target_os = "macos"), + not(all(target_os = "netbsd", not(target_vendor = "rumprun"))), + not(target_os = "openbsd"), + not(target_os = "solaris") +))] +#[cfg_attr(test, allow(dead_code))] +pub mod guard { + use crate::ops::Range; + pub type Guard = Range<usize>; + pub unsafe fn current() -> Option<Guard> { + None + } + pub unsafe fn init() -> Option<Guard> { + None + } +} + +#[cfg(any( + all(target_os = "linux", not(target_env = "musl")), + target_os = "freebsd", + target_os = "macos", + all(target_os = "netbsd", not(target_vendor = "rumprun")), + target_os = "openbsd", + target_os = "solaris" +))] +#[cfg_attr(test, allow(dead_code))] +pub mod guard { + use libc::{mmap, mprotect}; + use libc::{MAP_ANON, MAP_FAILED, MAP_FIXED, MAP_PRIVATE, PROT_NONE, PROT_READ, PROT_WRITE}; + + use crate::ops::Range; + use crate::sync::atomic::{AtomicUsize, Ordering}; + use crate::sys::os; + + // This is initialized in init() and only read from after + static PAGE_SIZE: AtomicUsize = AtomicUsize::new(0); + + pub type Guard = Range<usize>; + + #[cfg(target_os = "solaris")] + unsafe fn get_stack_start() -> Option<*mut libc::c_void> { + let mut current_stack: libc::stack_t = crate::mem::zeroed(); + assert_eq!(libc::stack_getbounds(&mut current_stack), 0); + Some(current_stack.ss_sp) + } + + #[cfg(target_os = "macos")] + unsafe fn get_stack_start() -> Option<*mut libc::c_void> { + let th = libc::pthread_self(); + let stackaddr = + libc::pthread_get_stackaddr_np(th) as usize - libc::pthread_get_stacksize_np(th); + Some(stackaddr as *mut libc::c_void) + } + + #[cfg(target_os = "openbsd")] + unsafe fn get_stack_start() -> Option<*mut libc::c_void> { + let mut current_stack: libc::stack_t = crate::mem::zeroed(); + assert_eq!(libc::pthread_stackseg_np(libc::pthread_self(), &mut current_stack), 0); + + let stackaddr = if libc::pthread_main_np() == 1 { + // main thread + current_stack.ss_sp as usize - current_stack.ss_size + PAGE_SIZE.load(Ordering::Relaxed) + } else { + // new thread + current_stack.ss_sp as usize - current_stack.ss_size + }; + Some(stackaddr as *mut libc::c_void) + } + + #[cfg(any( + target_os = "android", + target_os = "freebsd", + target_os = "linux", + target_os = "netbsd", + target_os = "l4re" + ))] + unsafe fn get_stack_start() -> Option<*mut libc::c_void> { + let mut ret = None; + let mut attr: libc::pthread_attr_t = crate::mem::zeroed(); + assert_eq!(libc::pthread_attr_init(&mut attr), 0); + #[cfg(target_os = "freebsd")] + let e = libc::pthread_attr_get_np(libc::pthread_self(), &mut attr); + #[cfg(not(target_os = "freebsd"))] + let e = libc::pthread_getattr_np(libc::pthread_self(), &mut attr); + if e == 0 { + let mut stackaddr = crate::ptr::null_mut(); + let mut stacksize = 0; + assert_eq!(libc::pthread_attr_getstack(&attr, &mut stackaddr, &mut stacksize), 0); + ret = Some(stackaddr); + } + assert_eq!(libc::pthread_attr_destroy(&mut attr), 0); + ret + } + + // Precondition: PAGE_SIZE is initialized. + unsafe fn get_stack_start_aligned() -> Option<*mut libc::c_void> { + let page_size = PAGE_SIZE.load(Ordering::Relaxed); + assert!(page_size != 0); + let stackaddr = get_stack_start()?; + + // Ensure stackaddr is page aligned! A parent process might + // have reset RLIMIT_STACK to be non-page aligned. The + // pthread_attr_getstack() reports the usable stack area + // stackaddr < stackaddr + stacksize, so if stackaddr is not + // page-aligned, calculate the fix such that stackaddr < + // new_page_aligned_stackaddr < stackaddr + stacksize + let remainder = (stackaddr as usize) % page_size; + Some(if remainder == 0 { + stackaddr + } else { + ((stackaddr as usize) + page_size - remainder) as *mut libc::c_void + }) + } + + pub unsafe fn init() -> Option<Guard> { + let page_size = os::page_size(); + PAGE_SIZE.store(page_size, Ordering::Relaxed); + + let stackaddr = get_stack_start_aligned()?; + + if cfg!(target_os = "linux") { + // 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. See #43052. + // + // 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. + let stackaddr = stackaddr as usize; + Some(stackaddr - page_size..stackaddr) + } else { + // Reallocate the last page of the stack. + // This ensures SIGBUS will be raised on + // stack overflow. + // Systems which enforce strict PAX MPROTECT do not allow + // to mprotect() a mapping with less restrictive permissions + // than the initial mmap() used, so we mmap() here with + // read/write permissions and only then mprotect() it to + // no permissions at all. See issue #50313. + let result = mmap( + stackaddr, + page_size, + PROT_READ | PROT_WRITE, + MAP_PRIVATE | MAP_ANON | MAP_FIXED, + -1, + 0, + ); + if result != stackaddr || result == MAP_FAILED { + panic!("failed to allocate a guard page"); + } + + let result = mprotect(stackaddr, page_size, PROT_NONE); + if result != 0 { + panic!("failed to protect the guard page"); + } + + let guardaddr = stackaddr as usize; + let offset = if cfg!(target_os = "freebsd") { 2 } else { 1 }; + + Some(guardaddr..guardaddr + offset * page_size) + } + } + + #[cfg(any(target_os = "macos", target_os = "openbsd", target_os = "solaris"))] + pub unsafe fn current() -> Option<Guard> { + let stackaddr = get_stack_start()? as usize; + Some(stackaddr - PAGE_SIZE.load(Ordering::Relaxed)..stackaddr) + } + + #[cfg(any( + target_os = "android", + target_os = "freebsd", + target_os = "linux", + target_os = "netbsd", + target_os = "l4re" + ))] + pub unsafe fn current() -> Option<Guard> { + let mut ret = None; + let mut attr: libc::pthread_attr_t = crate::mem::zeroed(); + assert_eq!(libc::pthread_attr_init(&mut attr), 0); + #[cfg(target_os = "freebsd")] + let e = libc::pthread_attr_get_np(libc::pthread_self(), &mut attr); + #[cfg(not(target_os = "freebsd"))] + let e = libc::pthread_getattr_np(libc::pthread_self(), &mut attr); + if e == 0 { + let mut guardsize = 0; + assert_eq!(libc::pthread_attr_getguardsize(&attr, &mut guardsize), 0); + if guardsize == 0 { + panic!("there is no guard page"); + } + let mut stackaddr = crate::ptr::null_mut(); + let mut size = 0; + assert_eq!(libc::pthread_attr_getstack(&attr, &mut stackaddr, &mut size), 0); + + let stackaddr = stackaddr as usize; + ret = if cfg!(target_os = "freebsd") { + // FIXME does freebsd really fault *below* the guard addr? + let guardaddr = stackaddr - guardsize; + Some(guardaddr - PAGE_SIZE.load(Ordering::Relaxed)..guardaddr) + } else if cfg!(target_os = "netbsd") { + Some(stackaddr - guardsize..stackaddr) + } else if cfg!(all(target_os = "linux", target_env = "gnu")) { + // glibc used to include the guard area within the stack, as noted in the BUGS + // section of `man pthread_attr_getguardsize`. This has been corrected starting + // with glibc 2.27, and in some distro backports, so the guard is now placed at the + // end (below) the stack. There's no easy way for us to know which we have at + // runtime, so we'll just match any fault in the range right above or below the + // stack base to call that fault a stack overflow. + Some(stackaddr - guardsize..stackaddr + guardsize) + } else { + Some(stackaddr..stackaddr + guardsize) + }; + } + assert_eq!(libc::pthread_attr_destroy(&mut attr), 0); + ret + } +} + +// glibc >= 2.15 has a __pthread_get_minstack() function that returns +// PTHREAD_STACK_MIN plus bytes needed for thread-local storage. +// We need that information to avoid blowing up when a small stack +// is created in an application with big thread-local storage requirements. +// See #6233 for rationale and details. +#[cfg(target_os = "linux")] +#[allow(deprecated)] +fn min_stack_size(attr: *const libc::pthread_attr_t) -> usize { + weak!(fn __pthread_get_minstack(*const libc::pthread_attr_t) -> libc::size_t); + + match __pthread_get_minstack.get() { + None => libc::PTHREAD_STACK_MIN, + Some(f) => unsafe { f(attr) }, + } +} + +// No point in looking up __pthread_get_minstack() on non-glibc +// platforms. +#[cfg(all(not(target_os = "linux"), not(target_os = "netbsd")))] +fn min_stack_size(_: *const libc::pthread_attr_t) -> usize { + libc::PTHREAD_STACK_MIN +} + +#[cfg(target_os = "netbsd")] +fn min_stack_size(_: *const libc::pthread_attr_t) -> usize { + 2048 // just a guess +} |