Merge pull request #19826 from lnicola/sync-from-rust

minor: Sync from downstream

13 files changed, 354 insertions, 375 deletions

diff --git a/library/std/src/sys/pal/hermit/mod.rs b/library/std/src/sys/pal/hermit/mod.rs
index ea636938d70..fb8d69b7375 100644
--- a/library/std/src/sys/pal/hermit/mod.rs
+++ b/library/std/src/sys/pal/hermit/mod.rs
@@ -43,15 +43,6 @@ pub fn abort_internal() -> ! {
     unsafe { hermit_abi::abort() }
 }
 
-// This function is needed by the panic runtime. The symbol is named in
-// pre-link args for the target specification, so keep that in sync.
-#[cfg(not(test))]
-#[unsafe(no_mangle)]
-// NB. used by both libunwind and libpanic_abort
-pub extern "C" fn __rust_abort() {
-    abort_internal();
-}
-
 // SAFETY: must be called only once during runtime initialization.
 // NOTE: this is not guaranteed to run, for example when Rust code is called externally.
 pub unsafe fn init(argc: isize, argv: *const *const u8, _sigpipe: u8) {
diff --git a/library/std/src/sys/pal/sgx/mod.rs b/library/std/src/sys/pal/sgx/mod.rs
index 3932f64c0ef..6e43a79ddec 100644
--- a/library/std/src/sys/pal/sgx/mod.rs
+++ b/library/std/src/sys/pal/sgx/mod.rs
@@ -112,11 +112,14 @@ pub fn abort_internal() -> ! {
     abi::usercalls::exit(true)
 }
 
-// This function is needed by the panic runtime. The symbol is named in
+// This function is needed by libunwind. The symbol is named in
 // pre-link args for the target specification, so keep that in sync.
+// Note: contrary to the `__rust_abort` in `crate::rt`, this uses `no_mangle`
+//       because it is actually used from C code. Because symbols annotated with
+//       #[rustc_std_internal_symbol] get mangled, this will not lead to linker
+//       conflicts.
 #[cfg(not(test))]
 #[unsafe(no_mangle)]
-// NB. used by both libunwind and libpanic_abort
 pub extern "C" fn __rust_abort() {
     abort_internal();
 }
diff --git a/library/std/src/sys/pal/uefi/mod.rs b/library/std/src/sys/pal/uefi/mod.rs
index 78fcfcb3b77..8911a2ee519 100644
--- a/library/std/src/sys/pal/uefi/mod.rs
+++ b/library/std/src/sys/pal/uefi/mod.rs
@@ -161,14 +161,6 @@ pub fn abort_internal() -> ! {
     core::intrinsics::abort();
 }
 
-// This function is needed by the panic runtime. The symbol is named in
-// pre-link args for the target specification, so keep that in sync.
-#[cfg(not(test))]
-#[unsafe(no_mangle)]
-pub extern "C" fn __rust_abort() {
-    abort_internal();
-}
-
 /// Disable access to BootServices if `EVT_SIGNAL_EXIT_BOOT_SERVICES` is signaled
 extern "efiapi" fn exit_boot_service_handler(_e: r_efi::efi::Event, _ctx: *mut crate::ffi::c_void) {
     uefi::env::disable_boot_services();
diff --git a/library/std/src/sys/pal/unix/fuchsia.rs b/library/std/src/sys/pal/unix/fuchsia.rs
index 7932bd26d76..c118dee6247 100644
--- a/library/std/src/sys/pal/unix/fuchsia.rs
+++ b/library/std/src/sys/pal/unix/fuchsia.rs
@@ -1,48 +1,35 @@
-#![allow(non_camel_case_types, unused)]
+#![expect(non_camel_case_types)]
 
-use libc::{c_int, c_void, size_t};
+use libc::size_t;
 
+use crate::ffi::{c_char, c_int, c_void};
 use crate::io;
-use crate::mem::MaybeUninit;
-use crate::os::raw::c_char;
 
-pub type zx_handle_t = u32;
-pub type zx_vaddr_t = usize;
-pub type zx_rights_t = u32;
-pub type zx_status_t = i32;
-
-pub const ZX_HANDLE_INVALID: zx_handle_t = 0;
+//////////
+// Time //
+//////////
 
 pub type zx_time_t = i64;
-pub const ZX_TIME_INFINITE: zx_time_t = i64::MAX;
-
-pub type zx_signals_t = u32;
-
-pub const ZX_OBJECT_SIGNAL_3: zx_signals_t = 1 << 3;
 
-pub const ZX_TASK_TERMINATED: zx_signals_t = ZX_OBJECT_SIGNAL_3;
+pub const ZX_TIME_INFINITE: zx_time_t = i64::MAX;
 
-pub const ZX_RIGHT_SAME_RIGHTS: zx_rights_t = 1 << 31;
+unsafe extern "C" {
+    pub safe fn zx_clock_get_monotonic() -> zx_time_t;
+}
 
-// The upper four bits gives the minor version.
-pub type zx_object_info_topic_t = u32;
+/////////////
+// Handles //
+/////////////
 
-pub const ZX_INFO_PROCESS: zx_object_info_topic_t = 3 | (1 << 28);
+pub type zx_handle_t = u32;
 
-pub type zx_info_process_flags_t = u32;
+pub const ZX_HANDLE_INVALID: zx_handle_t = 0;
 
-pub fn zx_cvt<T>(t: T) -> io::Result<T>
-where
-    T: TryInto<zx_status_t> + Copy,
-{
-    if let Ok(status) = TryInto::try_into(t) {
-        if status < 0 { Err(io::Error::from_raw_os_error(status)) } else { Ok(t) }
-    } else {
-        Err(io::Error::last_os_error())
-    }
+unsafe extern "C" {
+    pub fn zx_handle_close(handle: zx_handle_t) -> zx_status_t;
 }
 
-// Safe wrapper around zx_handle_t
+/// A safe wrapper around `zx_handle_t`.
 pub struct Handle {
     raw: zx_handle_t,
 }
@@ -65,6 +52,66 @@ impl Drop for Handle {
     }
 }
 
+///////////
+// Futex //
+///////////
+
+pub type zx_futex_t = crate::sync::atomic::Atomic<u32>;
+
+unsafe extern "C" {
+    pub fn zx_object_wait_one(
+        handle: zx_handle_t,
+        signals: zx_signals_t,
+        timeout: zx_time_t,
+        pending: *mut zx_signals_t,
+    ) -> zx_status_t;
+
+    pub fn zx_futex_wait(
+        value_ptr: *const zx_futex_t,
+        current_value: zx_futex_t,
+        new_futex_owner: zx_handle_t,
+        deadline: zx_time_t,
+    ) -> zx_status_t;
+    pub fn zx_futex_wake(value_ptr: *const zx_futex_t, wake_count: u32) -> zx_status_t;
+    pub fn zx_futex_wake_single_owner(value_ptr: *const zx_futex_t) -> zx_status_t;
+    pub safe fn zx_thread_self() -> zx_handle_t;
+}
+
+////////////////
+// Properties //
+////////////////
+
+pub const ZX_PROP_NAME: u32 = 3;
+
+unsafe extern "C" {
+    pub fn zx_object_set_property(
+        handle: zx_handle_t,
+        property: u32,
+        value: *const libc::c_void,
+        value_size: libc::size_t,
+    ) -> zx_status_t;
+}
+
+/////////////
+// Signals //
+/////////////
+
+pub type zx_signals_t = u32;
+
+pub const ZX_OBJECT_SIGNAL_3: zx_signals_t = 1 << 3;
+pub const ZX_TASK_TERMINATED: zx_signals_t = ZX_OBJECT_SIGNAL_3;
+
+/////////////////
+// Object info //
+/////////////////
+
+// The upper four bits gives the minor version.
+pub type zx_object_info_topic_t = u32;
+
+pub const ZX_INFO_PROCESS: zx_object_info_topic_t = 3 | (1 << 28);
+
+pub type zx_info_process_flags_t = u32;
+
 // Returned for topic ZX_INFO_PROCESS
 #[derive(Default)]
 #[repr(C)]
@@ -76,25 +123,6 @@ pub struct zx_info_process_t {
 }
 
 unsafe extern "C" {
-    pub fn zx_job_default() -> zx_handle_t;
-
-    pub fn zx_task_kill(handle: zx_handle_t) -> zx_status_t;
-
-    pub fn zx_handle_close(handle: zx_handle_t) -> zx_status_t;
-
-    pub fn zx_handle_duplicate(
-        handle: zx_handle_t,
-        rights: zx_rights_t,
-        out: *const zx_handle_t,
-    ) -> zx_handle_t;
-
-    pub fn zx_object_wait_one(
-        handle: zx_handle_t,
-        signals: zx_signals_t,
-        timeout: zx_time_t,
-        pending: *mut zx_signals_t,
-    ) -> zx_status_t;
-
     pub fn zx_object_get_info(
         handle: zx_handle_t,
         topic: u32,
@@ -105,6 +133,10 @@ unsafe extern "C" {
     ) -> zx_status_t;
 }
 
+///////////////
+// Processes //
+///////////////
+
 #[derive(Default)]
 #[repr(C)]
 pub struct fdio_spawn_action_t {
@@ -130,6 +162,8 @@ unsafe extern "C" {
 
     pub fn fdio_fd_clone(fd: c_int, out_handle: *mut zx_handle_t) -> zx_status_t;
     pub fn fdio_fd_create(handle: zx_handle_t, fd: *mut c_int) -> zx_status_t;
+
+    pub fn zx_task_kill(handle: zx_handle_t) -> zx_status_t;
 }
 
 // fdio_spawn_etc flags
@@ -137,173 +171,34 @@ unsafe extern "C" {
 pub const FDIO_SPAWN_CLONE_JOB: u32 = 0x0001;
 pub const FDIO_SPAWN_CLONE_LDSVC: u32 = 0x0002;
 pub const FDIO_SPAWN_CLONE_NAMESPACE: u32 = 0x0004;
-pub const FDIO_SPAWN_CLONE_STDIO: u32 = 0x0008;
 pub const FDIO_SPAWN_CLONE_ENVIRON: u32 = 0x0010;
 pub const FDIO_SPAWN_CLONE_UTC_CLOCK: u32 = 0x0020;
-pub const FDIO_SPAWN_CLONE_ALL: u32 = 0xFFFF;
 
 // fdio_spawn_etc actions
 
-pub const FDIO_SPAWN_ACTION_CLONE_FD: u32 = 0x0001;
 pub const FDIO_SPAWN_ACTION_TRANSFER_FD: u32 = 0x0002;
 
-// Errors
-
-#[allow(unused)]
-pub const ERR_INTERNAL: zx_status_t = -1;
-
-// ERR_NOT_SUPPORTED: The operation is not implemented, supported,
-// or enabled.
-#[allow(unused)]
-pub const ERR_NOT_SUPPORTED: zx_status_t = -2;
-
-// ERR_NO_RESOURCES: The system was not able to allocate some resource
-// needed for the operation.
-#[allow(unused)]
-pub const ERR_NO_RESOURCES: zx_status_t = -3;
-
-// ERR_NO_MEMORY: The system was not able to allocate memory needed
-// for the operation.
-#[allow(unused)]
-pub const ERR_NO_MEMORY: zx_status_t = -4;
-
-// ERR_CALL_FAILED: The second phase of zx_channel_call(; did not complete
-// successfully.
-#[allow(unused)]
-pub const ERR_CALL_FAILED: zx_status_t = -5;
-
-// ERR_INTERRUPTED_RETRY: The system call was interrupted, but should be
-// retried.  This should not be seen outside of the VDSO.
-#[allow(unused)]
-pub const ERR_INTERRUPTED_RETRY: zx_status_t = -6;
-
-// ======= Parameter errors =======
-// ERR_INVALID_ARGS: an argument is invalid, ex. null pointer
-#[allow(unused)]
-pub const ERR_INVALID_ARGS: zx_status_t = -10;
-
-// ERR_BAD_HANDLE: A specified handle value does not refer to a handle.
-#[allow(unused)]
-pub const ERR_BAD_HANDLE: zx_status_t = -11;
-
-// ERR_WRONG_TYPE: The subject of the operation is the wrong type to
-// perform the operation.
-// Example: Attempting a message_read on a thread handle.
-#[allow(unused)]
-pub const ERR_WRONG_TYPE: zx_status_t = -12;
-
-// ERR_BAD_SYSCALL: The specified syscall number is invalid.
-#[allow(unused)]
-pub const ERR_BAD_SYSCALL: zx_status_t = -13;
-
-// ERR_OUT_OF_RANGE: An argument is outside the valid range for this
-// operation.
-#[allow(unused)]
-pub const ERR_OUT_OF_RANGE: zx_status_t = -14;
-
-// ERR_BUFFER_TOO_SMALL: A caller provided buffer is too small for
-// this operation.
-#[allow(unused)]
-pub const ERR_BUFFER_TOO_SMALL: zx_status_t = -15;
-
-// ======= Precondition or state errors =======
-// ERR_BAD_STATE: operation failed because the current state of the
-// object does not allow it, or a precondition of the operation is
-// not satisfied
-#[allow(unused)]
-pub const ERR_BAD_STATE: zx_status_t = -20;
-
-// ERR_TIMED_OUT: The time limit for the operation elapsed before
-// the operation completed.
-#[allow(unused)]
-pub const ERR_TIMED_OUT: zx_status_t = -21;
-
-// ERR_SHOULD_WAIT: The operation cannot be performed currently but
-// potentially could succeed if the caller waits for a prerequisite
-// to be satisfied, for example waiting for a handle to be readable
-// or writable.
-// Example: Attempting to read from a message pipe that has no
-// messages waiting but has an open remote will return ERR_SHOULD_WAIT.
-// Attempting to read from a message pipe that has no messages waiting
-// and has a closed remote end will return ERR_REMOTE_CLOSED.
-#[allow(unused)]
-pub const ERR_SHOULD_WAIT: zx_status_t = -22;
-
-// ERR_CANCELED: The in-progress operation (e.g., a wait) has been
-// // canceled.
-#[allow(unused)]
-pub const ERR_CANCELED: zx_status_t = -23;
-
-// ERR_PEER_CLOSED: The operation failed because the remote end
-// of the subject of the operation was closed.
-#[allow(unused)]
-pub const ERR_PEER_CLOSED: zx_status_t = -24;
-
-// ERR_NOT_FOUND: The requested entity is not found.
-#[allow(unused)]
-pub const ERR_NOT_FOUND: zx_status_t = -25;
-
-// ERR_ALREADY_EXISTS: An object with the specified identifier
-// already exists.
-// Example: Attempting to create a file when a file already exists
-// with that name.
-#[allow(unused)]
-pub const ERR_ALREADY_EXISTS: zx_status_t = -26;
-
-// ERR_ALREADY_BOUND: The operation failed because the named entity
-// is already owned or controlled by another entity. The operation
-// could succeed later if the current owner releases the entity.
-#[allow(unused)]
-pub const ERR_ALREADY_BOUND: zx_status_t = -27;
-
-// ERR_UNAVAILABLE: The subject of the operation is currently unable
-// to perform the operation.
-// Note: This is used when there's no direct way for the caller to
-// observe when the subject will be able to perform the operation
-// and should thus retry.
-#[allow(unused)]
-pub const ERR_UNAVAILABLE: zx_status_t = -28;
-
-// ======= Permission check errors =======
-// ERR_ACCESS_DENIED: The caller did not have permission to perform
-// the specified operation.
-#[allow(unused)]
-pub const ERR_ACCESS_DENIED: zx_status_t = -30;
-
-// ======= Input-output errors =======
-// ERR_IO: Otherwise unspecified error occurred during I/O.
-#[allow(unused)]
-pub const ERR_IO: zx_status_t = -40;
-
-// ERR_REFUSED: The entity the I/O operation is being performed on
-// rejected the operation.
-// Example: an I2C device NAK'ing a transaction or a disk controller
-// rejecting an invalid command.
-#[allow(unused)]
-pub const ERR_IO_REFUSED: zx_status_t = -41;
-
-// ERR_IO_DATA_INTEGRITY: The data in the operation failed an integrity
-// check and is possibly corrupted.
-// Example: CRC or Parity error.
-#[allow(unused)]
-pub const ERR_IO_DATA_INTEGRITY: zx_status_t = -42;
-
-// ERR_IO_DATA_LOSS: The data in the operation is currently unavailable
-// and may be permanently lost.
-// Example: A disk block is irrecoverably damaged.
-#[allow(unused)]
-pub const ERR_IO_DATA_LOSS: zx_status_t = -43;
-
-// Filesystem specific errors
-#[allow(unused)]
-pub const ERR_BAD_PATH: zx_status_t = -50;
-#[allow(unused)]
-pub const ERR_NOT_DIR: zx_status_t = -51;
-#[allow(unused)]
-pub const ERR_NOT_FILE: zx_status_t = -52;
-// ERR_FILE_BIG: A file exceeds a filesystem-specific size limit.
-#[allow(unused)]
-pub const ERR_FILE_BIG: zx_status_t = -53;
-// ERR_NO_SPACE: Filesystem or device space is exhausted.
-#[allow(unused)]
-pub const ERR_NO_SPACE: zx_status_t = -54;
+////////////
+// Errors //
+////////////
+
+pub type zx_status_t = i32;
+
+pub const ZX_OK: zx_status_t = 0;
+pub const ZX_ERR_NOT_SUPPORTED: zx_status_t = -2;
+pub const ZX_ERR_INVALID_ARGS: zx_status_t = -10;
+pub const ZX_ERR_BAD_HANDLE: zx_status_t = -11;
+pub const ZX_ERR_WRONG_TYPE: zx_status_t = -12;
+pub const ZX_ERR_BAD_STATE: zx_status_t = -20;
+pub const ZX_ERR_TIMED_OUT: zx_status_t = -21;
+
+pub fn zx_cvt<T>(t: T) -> io::Result<T>
+where
+    T: TryInto<zx_status_t> + Copy,
+{
+    if let Ok(status) = TryInto::try_into(t) {
+        if status < 0 { Err(io::Error::from_raw_os_error(status)) } else { Ok(t) }
+    } else {
+        Err(io::Error::last_os_error())
+    }
+}
diff --git a/library/std/src/sys/pal/unix/futex.rs b/library/std/src/sys/pal/unix/futex.rs
index 8d89163c42c..c23278bdf5e 100644
--- a/library/std/src/sys/pal/unix/futex.rs
+++ b/library/std/src/sys/pal/unix/futex.rs
@@ -255,66 +255,28 @@ pub fn futex_wake_all(futex: &Atomic<u32>) {
 }
 
 #[cfg(target_os = "fuchsia")]
-pub mod zircon {
-    pub type zx_futex_t = crate::sync::atomic::Atomic<u32>;
-    pub type zx_handle_t = u32;
-    pub type zx_status_t = i32;
-    pub type zx_time_t = i64;
-
-    pub const ZX_HANDLE_INVALID: zx_handle_t = 0;
-
-    pub const ZX_TIME_INFINITE: zx_time_t = zx_time_t::MAX;
-
-    pub const ZX_OK: zx_status_t = 0;
-    pub const ZX_ERR_INVALID_ARGS: zx_status_t = -10;
-    pub const ZX_ERR_BAD_HANDLE: zx_status_t = -11;
-    pub const ZX_ERR_WRONG_TYPE: zx_status_t = -12;
-    pub const ZX_ERR_BAD_STATE: zx_status_t = -20;
-    pub const ZX_ERR_TIMED_OUT: zx_status_t = -21;
-
-    unsafe extern "C" {
-        pub fn zx_clock_get_monotonic() -> zx_time_t;
-        pub fn zx_futex_wait(
-            value_ptr: *const zx_futex_t,
-            current_value: zx_futex_t,
-            new_futex_owner: zx_handle_t,
-            deadline: zx_time_t,
-        ) -> zx_status_t;
-        pub fn zx_futex_wake(value_ptr: *const zx_futex_t, wake_count: u32) -> zx_status_t;
-        pub fn zx_futex_wake_single_owner(value_ptr: *const zx_futex_t) -> zx_status_t;
-        pub fn zx_thread_self() -> zx_handle_t;
-    }
-}
-
-#[cfg(target_os = "fuchsia")]
 pub fn futex_wait(futex: &Atomic<u32>, expected: u32, timeout: Option<Duration>) -> bool {
+    use super::fuchsia::*;
+
     // Sleep forever if the timeout is longer than fits in a i64.
     let deadline = timeout
-        .and_then(|d| {
-            i64::try_from(d.as_nanos())
-                .ok()?
-                .checked_add(unsafe { zircon::zx_clock_get_monotonic() })
-        })
-        .unwrap_or(zircon::ZX_TIME_INFINITE);
+        .and_then(|d| i64::try_from(d.as_nanos()).ok()?.checked_add(zx_clock_get_monotonic()))
+        .unwrap_or(ZX_TIME_INFINITE);
 
     unsafe {
-        zircon::zx_futex_wait(
-            futex,
-            core::sync::atomic::AtomicU32::new(expected),
-            zircon::ZX_HANDLE_INVALID,
-            deadline,
-        ) != zircon::ZX_ERR_TIMED_OUT
+        zx_futex_wait(futex, zx_futex_t::new(expected), ZX_HANDLE_INVALID, deadline)
+            != ZX_ERR_TIMED_OUT
     }
 }
 
 // Fuchsia doesn't tell us how many threads are woken up, so this always returns false.
 #[cfg(target_os = "fuchsia")]
 pub fn futex_wake(futex: &Atomic<u32>) -> bool {
-    unsafe { zircon::zx_futex_wake(futex, 1) };
+    unsafe { super::fuchsia::zx_futex_wake(futex, 1) };
     false
 }
 
 #[cfg(target_os = "fuchsia")]
 pub fn futex_wake_all(futex: &Atomic<u32>) {
-    unsafe { zircon::zx_futex_wake(futex, u32::MAX) };
+    unsafe { super::fuchsia::zx_futex_wake(futex, u32::MAX) };
 }
diff --git a/library/std/src/sys/pal/unix/os.rs b/library/std/src/sys/pal/unix/os.rs
index 4883303b88e..48609030aed 100644
--- a/library/std/src/sys/pal/unix/os.rs
+++ b/library/std/src/sys/pal/unix/os.rs
@@ -56,7 +56,7 @@ unsafe extern "C" {
     #[cfg_attr(target_os = "aix", link_name = "_Errno")]
     // SAFETY: this will always return the same pointer on a given thread.
     #[unsafe(ffi_const)]
-    fn errno_location() -> *mut c_int;
+    pub safe fn errno_location() -> *mut c_int;
 }
 
 /// Returns the platform-specific value of errno
diff --git a/library/std/src/sys/pal/unix/stack_overflow.rs b/library/std/src/sys/pal/unix/stack_overflow.rs
index 8bf6d833515..a3be2cdf738 100644
--- a/library/std/src/sys/pal/unix/stack_overflow.rs
+++ b/library/std/src/sys/pal/unix/stack_overflow.rs
@@ -25,15 +25,36 @@ impl Drop for Handler {
     }
 }
 
-#[cfg(any(
-    target_os = "linux",
-    target_os = "freebsd",
-    target_os = "hurd",
-    target_os = "macos",
-    target_os = "netbsd",
-    target_os = "openbsd",
-    target_os = "solaris",
-    target_os = "illumos",
+#[cfg(all(
+    not(miri),
+    any(
+        target_os = "linux",
+        target_os = "freebsd",
+        target_os = "hurd",
+        target_os = "macos",
+        target_os = "netbsd",
+        target_os = "openbsd",
+        target_os = "solaris",
+        target_os = "illumos",
+    ),
+))]
+mod thread_info;
+
+// miri doesn't model signals nor stack overflows and this code has some
+// synchronization properties that we don't want to expose to user code,
+// hence we disable it on miri.
+#[cfg(all(
+    not(miri),
+    any(
+        target_os = "linux",
+        target_os = "freebsd",
+        target_os = "hurd",
+        target_os = "macos",
+        target_os = "netbsd",
+        target_os = "openbsd",
+        target_os = "solaris",
+        target_os = "illumos",
+    )
 ))]
 mod imp {
     use libc::{
@@ -46,22 +67,13 @@ mod imp {
     use libc::{mmap64, mprotect, munmap};
 
     use super::Handler;
-    use crate::cell::Cell;
+    use super::thread_info::{delete_current_info, set_current_info, with_current_info};
     use crate::ops::Range;
     use crate::sync::OnceLock;
     use crate::sync::atomic::{Atomic, AtomicBool, AtomicPtr, AtomicUsize, Ordering};
     use crate::sys::pal::unix::os;
-    use crate::{io, mem, ptr, thread};
-
-    // We use a TLS variable to store the address of the guard page. While TLS
-    // variables are not guaranteed to be signal-safe, this works out in practice
-    // since we make sure to write to the variable before the signal stack is
-    // installed, thereby ensuring that the variable is always allocated when
-    // the signal handler is called.
-    thread_local! {
-        // FIXME: use `Range` once that implements `Copy`.
-        static GUARD: Cell<(usize, usize)> = const { Cell::new((0, 0)) };
-    }
+    use crate::thread::with_current_name;
+    use crate::{io, mem, panic, ptr};
 
     // Signal handler for the SIGSEGV and SIGBUS handlers. We've got guard pages
     // (unmapped pages) at the end of every thread's stack, so if a thread ends
@@ -93,29 +105,35 @@ mod imp {
         info: *mut libc::siginfo_t,
         _data: *mut libc::c_void,
     ) {
-        let (start, end) = GUARD.get();
         // SAFETY: this pointer is provided by the system and will always point to a valid `siginfo_t`.
-        let addr = unsafe { (*info).si_addr().addr() };
+        let fault_addr = unsafe { (*info).si_addr().addr() };
+
+        // `with_current_info` expects that the process aborts after it is
+        // called. If the signal was not caused by a memory access, this might
+        // not be true. We detect this by noticing that the `si_addr` field is
+        // zero if the signal is synthetic.
+        if fault_addr != 0 {
+            with_current_info(|thread_info| {
+                // If the faulting address is within the guard page, then we print a
+                // message saying so and abort.
+                if let Some(thread_info) = thread_info
+                    && thread_info.guard_page_range.contains(&fault_addr)
+                {
+                    let name = thread_info.thread_name.as_deref().unwrap_or("<unknown>");
+                    rtprintpanic!("\nthread '{name}' has overflowed its stack\n");
+                    rtabort!("stack overflow");
+                }
+            })
+        }
 
-        // If the faulting address is within the guard page, then we print a
-        // message saying so and abort.
-        if start <= addr && addr < end {
-            thread::with_current_name(|name| {
-                let name = name.unwrap_or("<unknown>");
-                rtprintpanic!("\nthread '{name}' has overflowed its stack\n");
-            });
+        // Unregister ourselves by reverting back to the default behavior.
+        // SAFETY: assuming all platforms define struct sigaction as "zero-initializable"
+        let mut action: sigaction = unsafe { mem::zeroed() };
+        action.sa_sigaction = SIG_DFL;
+        // SAFETY: pray this is a well-behaved POSIX implementation of fn sigaction
+        unsafe { sigaction(signum, &action, ptr::null_mut()) };
 
-            rtabort!("stack overflow");
-        } else {
-            // Unregister ourselves by reverting back to the default behavior.
-            // SAFETY: assuming all platforms define struct sigaction as "zero-initializable"
-            let mut action: sigaction = unsafe { mem::zeroed() };
-            action.sa_sigaction = SIG_DFL;
-            // SAFETY: pray this is a well-behaved POSIX implementation of fn sigaction
-            unsafe { sigaction(signum, &action, ptr::null_mut()) };
-
-            // See comment above for why this function returns.
-        }
+        // See comment above for why this function returns.
     }
 
     static PAGE_SIZE: Atomic<usize> = AtomicUsize::new(0);
@@ -128,9 +146,7 @@ mod imp {
     pub unsafe fn init() {
         PAGE_SIZE.store(os::page_size(), Ordering::Relaxed);
 
-        // Always write to GUARD to ensure the TLS variable is allocated.
-        let guard = unsafe { install_main_guard().unwrap_or(0..0) };
-        GUARD.set((guard.start, guard.end));
+        let mut guard_page_range = unsafe { install_main_guard() };
 
         // SAFETY: assuming all platforms define struct sigaction as "zero-initializable"
         let mut action: sigaction = unsafe { mem::zeroed() };
@@ -145,7 +161,13 @@ mod imp {
                     let handler = unsafe { make_handler(true) };
                     MAIN_ALTSTACK.store(handler.data, Ordering::Relaxed);
                     mem::forget(handler);
+
+                    if let Some(guard_page_range) = guard_page_range.take() {
+                        let thread_name = with_current_name(|name| name.map(Box::from));
+                        set_current_info(guard_page_range, thread_name);
+                    }
                 }
+
                 action.sa_flags = SA_SIGINFO | SA_ONSTACK;
                 action.sa_sigaction = signal_handler as sighandler_t;
                 // SAFETY: only overriding signals if the default is set
@@ -214,9 +236,10 @@ mod imp {
         }
 
         if !main_thread {
-            // Always write to GUARD to ensure the TLS variable is allocated.
-            let guard = unsafe { current_guard() }.unwrap_or(0..0);
-            GUARD.set((guard.start, guard.end));
+            if let Some(guard_page_range) = unsafe { current_guard() } {
+                let thread_name = with_current_name(|name| name.map(Box::from));
+                set_current_info(guard_page_range, thread_name);
+            }
         }
 
         // SAFETY: assuming stack_t is zero-initializable
@@ -261,6 +284,8 @@ mod imp {
             // a mapping that started one page earlier, so walk back a page and unmap from there.
             unsafe { munmap(data.sub(page_size), sigstack_size + page_size) };
         }
+
+        delete_current_info();
     }
 
     /// Modern kernels on modern hardware can have dynamic signal stack sizes.
@@ -590,17 +615,20 @@ mod imp {
 // usually have fewer qualms about forwards compatibility, since the runtime
 // is shipped with the OS):
 // <https://github.com/apple/swift/blob/swift-5.10-RELEASE/stdlib/public/runtime/CrashHandlerMacOS.cpp>
-#[cfg(not(any(
-    target_os = "linux",
-    target_os = "freebsd",
-    target_os = "hurd",
-    target_os = "macos",
-    target_os = "netbsd",
-    target_os = "openbsd",
-    target_os = "solaris",
-    target_os = "illumos",
-    target_os = "cygwin",
-)))]
+#[cfg(any(
+    miri,
+    not(any(
+        target_os = "linux",
+        target_os = "freebsd",
+        target_os = "hurd",
+        target_os = "macos",
+        target_os = "netbsd",
+        target_os = "openbsd",
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "cygwin",
+    ))
+))]
 mod imp {
     pub unsafe fn init() {}
 
diff --git a/library/std/src/sys/pal/unix/stack_overflow/thread_info.rs b/library/std/src/sys/pal/unix/stack_overflow/thread_info.rs
new file mode 100644
index 00000000000..e81429b98a6
--- /dev/null
+++ b/library/std/src/sys/pal/unix/stack_overflow/thread_info.rs
@@ -0,0 +1,129 @@
+//! TLS, but async-signal-safe.
+//!
+//! Unfortunately, because thread local storage isn't async-signal-safe, we
+//! cannot soundly use it in our stack overflow handler. While this works
+//! without problems on most platforms, it can lead to undefined behaviour
+//! on others (such as GNU/Linux). Luckily, the POSIX specification documents
+//! two thread-specific values that can be accessed in asynchronous signal
+//! handlers: the value of `pthread_self()` and the address of `errno`. As
+//! `pthread_t` is an opaque platform-specific type, we use the address of
+//! `errno` here. As it is thread-specific and does not change over the
+//! lifetime of a thread, we can use `&errno` as a key for a `BTreeMap`
+//! that stores thread-specific data.
+//!
+//! Concurrent access to this map is synchronized by two locks – an outer
+//! [`Mutex`] and an inner spin lock that also remembers the identity of
+//! the lock owner:
+//! * The spin lock is the primary means of synchronization: since it only
+//!   uses native atomics, it can be soundly used inside the signal handle
+//!   as opposed to [`Mutex`], which might not be async-signal-safe.
+//! * The [`Mutex`] prevents busy-waiting in the setup logic, as all accesses
+//!   there are performed with the [`Mutex`] held, which makes the spin-lock
+//!   redundant in the common case.
+//! * Finally, by using the `errno` address as the locked value of the spin
+//!   lock, we can detect cases where a SIGSEGV occurred while the thread
+//!   info is being modified.
+
+use crate::collections::BTreeMap;
+use crate::hint::spin_loop;
+use crate::ops::Range;
+use crate::sync::Mutex;
+use crate::sync::atomic::{AtomicUsize, Ordering};
+use crate::sys::os::errno_location;
+
+pub struct ThreadInfo {
+    pub guard_page_range: Range<usize>,
+    pub thread_name: Option<Box<str>>,
+}
+
+static LOCK: Mutex<()> = Mutex::new(());
+static SPIN_LOCK: AtomicUsize = AtomicUsize::new(0);
+// This uses a `BTreeMap` instead of a hashmap since it supports constant
+// initialization and automatically reduces the amount of memory used when
+// items are removed.
+static mut THREAD_INFO: BTreeMap<usize, ThreadInfo> = BTreeMap::new();
+
+struct UnlockOnDrop;
+
+impl Drop for UnlockOnDrop {
+    fn drop(&mut self) {
+        SPIN_LOCK.store(0, Ordering::Release);
+    }
+}
+
+/// Get the current thread's information, if available.
+///
+/// Calling this function might freeze other threads if they attempt to modify
+/// their thread information. Thus, the caller should ensure that the process
+/// is aborted shortly after this function is called.
+///
+/// This function is guaranteed to be async-signal-safe if `f` is too.
+pub fn with_current_info<R>(f: impl FnOnce(Option<&ThreadInfo>) -> R) -> R {
+    let this = errno_location().addr();
+    let mut attempt = 0;
+    let _guard = loop {
+        // If we are just spinning endlessly, it's very likely that the thread
+        // modifying the thread info map has a lower priority than us and will
+        // not continue until we stop running. Just give up in that case.
+        if attempt == 10_000_000 {
+            rtprintpanic!("deadlock in SIGSEGV handler");
+            return f(None);
+        }
+
+        match SPIN_LOCK.compare_exchange(0, this, Ordering::Acquire, Ordering::Relaxed) {
+            Ok(_) => break UnlockOnDrop,
+            Err(owner) if owner == this => {
+                rtabort!("a thread received SIGSEGV while modifying its stack overflow information")
+            }
+            // Spin until the lock can be acquired – there is nothing better to
+            // do. This is unfortunately a priority hole, but a stack overflow
+            // is a fatal error anyway.
+            Err(_) => {
+                spin_loop();
+                attempt += 1;
+            }
+        }
+    };
+
+    // SAFETY: we own the spin lock, so `THREAD_INFO` cannot not be aliased.
+    let thread_info = unsafe { &*(&raw const THREAD_INFO) };
+    f(thread_info.get(&this))
+}
+
+fn spin_lock_in_setup(this: usize) -> UnlockOnDrop {
+    loop {
+        match SPIN_LOCK.compare_exchange(0, this, Ordering::Acquire, Ordering::Relaxed) {
+            Ok(_) => return UnlockOnDrop,
+            Err(owner) if owner == this => {
+                unreachable!("the thread info setup logic isn't recursive")
+            }
+            // This function is always called with the outer lock held,
+            // meaning the only time locking can fail is if another thread has
+            // encountered a stack overflow. Since that will abort the process,
+            // we just stop the current thread until that time. We use `pause`
+            // instead of spinning to avoid priority inversion.
+            // SAFETY: this doesn't have any safety preconditions.
+            Err(_) => drop(unsafe { libc::pause() }),
+        }
+    }
+}
+
+pub fn set_current_info(guard_page_range: Range<usize>, thread_name: Option<Box<str>>) {
+    let this = errno_location().addr();
+    let _lock_guard = LOCK.lock();
+    let _spin_guard = spin_lock_in_setup(this);
+
+    // SAFETY: we own the spin lock, so `THREAD_INFO` cannot be aliased.
+    let thread_info = unsafe { &mut *(&raw mut THREAD_INFO) };
+    thread_info.insert(this, ThreadInfo { guard_page_range, thread_name });
+}
+
+pub fn delete_current_info() {
+    let this = errno_location().addr();
+    let _lock_guard = LOCK.lock();
+    let _spin_guard = spin_lock_in_setup(this);
+
+    // SAFETY: we own the spin lock, so `THREAD_INFO` cannot not be aliased.
+    let thread_info = unsafe { &mut *(&raw mut THREAD_INFO) };
+    thread_info.remove(&this);
+}
diff --git a/library/std/src/sys/pal/unix/thread.rs b/library/std/src/sys/pal/unix/thread.rs
index 4cdc2eaf0e5..d8b189413f4 100644
--- a/library/std/src/sys/pal/unix/thread.rs
+++ b/library/std/src/sys/pal/unix/thread.rs
@@ -22,23 +22,6 @@ pub const DEFAULT_MIN_STACK_SIZE: usize = 256 * 1024;
 #[cfg(any(target_os = "espidf", target_os = "nuttx"))]
 pub const DEFAULT_MIN_STACK_SIZE: usize = 0; // 0 indicates that the stack size configured in the ESP-IDF/NuttX menuconfig system should be used
 
-#[cfg(target_os = "fuchsia")]
-mod zircon {
-    type zx_handle_t = u32;
-    type zx_status_t = i32;
-    pub const ZX_PROP_NAME: u32 = 3;
-
-    unsafe extern "C" {
-        pub fn zx_object_set_property(
-            handle: zx_handle_t,
-            property: u32,
-            value: *const libc::c_void,
-            value_size: libc::size_t,
-        ) -> zx_status_t;
-        pub fn zx_thread_self() -> zx_handle_t;
-    }
-}
-
 pub struct Thread {
     id: libc::pthread_t,
 }
@@ -216,7 +199,7 @@ impl Thread {
 
     #[cfg(target_os = "fuchsia")]
     pub fn set_name(name: &CStr) {
-        use self::zircon::*;
+        use super::fuchsia::*;
         unsafe {
             zx_object_set_property(
                 zx_thread_self(),
@@ -239,16 +222,8 @@ impl Thread {
 
     #[cfg(target_os = "vxworks")]
     pub fn set_name(name: &CStr) {
-        // FIXME(libc): adding real STATUS, ERROR type eventually.
-        unsafe extern "C" {
-            fn taskNameSet(task_id: libc::TASK_ID, task_name: *mut libc::c_char) -> libc::c_int;
-        }
-
-        //  VX_TASK_NAME_LEN is 31 in VxWorks 7.
-        const VX_TASK_NAME_LEN: usize = 31;
-
-        let mut name = truncate_cstr::<{ VX_TASK_NAME_LEN }>(name);
-        let res = unsafe { taskNameSet(libc::taskIdSelf(), name.as_mut_ptr()) };
+        let mut name = truncate_cstr::<{ libc::VX_TASK_RENAME_LENGTH - 1 }>(name);
+        let res = unsafe { libc::taskNameSet(libc::taskIdSelf(), name.as_mut_ptr()) };
         debug_assert_eq!(res, libc::OK);
     }
 
diff --git a/library/std/src/sys/pal/windows/mod.rs b/library/std/src/sys/pal/windows/mod.rs
index 4f18c4009ab..8f54e2376eb 100644
--- a/library/std/src/sys/pal/windows/mod.rs
+++ b/library/std/src/sys/pal/windows/mod.rs
@@ -328,8 +328,12 @@ pub fn dur2timeout(dur: Duration) -> u32 {
 
 /// Use `__fastfail` to abort the process
 ///
-/// This is the same implementation as in libpanic_abort's `__rust_start_panic`. See
-/// that function for more information on `__fastfail`
+/// In Windows 8 and later, this will terminate the process immediately without
+/// running any in-process exception handlers. In earlier versions of Windows,
+/// this sequence of instructions will be treated as an access violation, which
+/// will still terminate the process but might run some exception handlers.
+///
+/// https://docs.microsoft.com/en-us/cpp/intrinsics/fastfail
 #[cfg(not(miri))] // inline assembly does not work in Miri
 pub fn abort_internal() -> ! {
     unsafe {
diff --git a/library/std/src/sys/pal/windows/os.rs b/library/std/src/sys/pal/windows/os.rs
index f331282d2d7..1ebbbec9e91 100644
--- a/library/std/src/sys/pal/windows/os.rs
+++ b/library/std/src/sys/pal/windows/os.rs
@@ -202,6 +202,8 @@ fn home_dir_crt() -> Option<PathBuf> {
             |buf, mut sz| {
                 // GetUserProfileDirectoryW does not quite use the usual protocol for
                 // negotiating the buffer size, so we have to translate.
+                // FIXME(#141254): We rely on the *undocumented* property that this function will
+                // always set the size, not just on failure.
                 match c::GetUserProfileDirectoryW(
                     ptr::without_provenance_mut(CURRENT_PROCESS_TOKEN),
                     buf,
diff --git a/library/std/src/sys/pal/xous/mod.rs b/library/std/src/sys/pal/xous/mod.rs
index 383d031ed43..042c4ff862f 100644
--- a/library/std/src/sys/pal/xous/mod.rs
+++ b/library/std/src/sys/pal/xous/mod.rs
@@ -1,5 +1,7 @@
 #![forbid(unsafe_op_in_unsafe_fn)]
 
+use crate::os::xous::ffi::exit;
+
 pub mod os;
 #[path = "../unsupported/pipe.rs"]
 pub mod pipe;
@@ -9,3 +11,7 @@ pub mod time;
 #[path = "../unsupported/common.rs"]
 mod common;
 pub use common::*;
+
+pub fn abort_internal() -> ! {
+    exit(101);
+}
diff --git a/library/std/src/sys/pal/xous/os.rs b/library/std/src/sys/pal/xous/os.rs
index 2230dabe096..d612a27d2bd 100644
--- a/library/std/src/sys/pal/xous/os.rs
+++ b/library/std/src/sys/pal/xous/os.rs
@@ -62,14 +62,6 @@ mod c_compat {
         }
         exit(unsafe { main() });
     }
-
-    // This function is needed by the panic runtime. The symbol is named in
-    // pre-link args for the target specification, so keep that in sync.
-    #[unsafe(no_mangle)]
-    // NB. used by both libunwind and libpanic_abort
-    pub extern "C" fn __rust_abort() -> ! {
-        exit(101);
-    }
 }
 
 pub fn errno() -> i32 {