Rollup merge of rust-lang#95916 - solid-rs:feat-kmc-solid-abort, r=Mark-Simulacrum

kmc-solid: Use `libc::abort` to abort a program

This PR updates the target-specific abort subroutine for the [`*-kmc-solid_*`](https://doc.rust-lang.org/nightly/rustc/platform-support/kmc-solid.html) Tier 3 targets.

The current implementation uses a `hlt` instruction, which is the most direct way to notify a connected debugger but is not the most flexible way. This PR changes it to call the `abort` libc function, making it possible for a system designer to override its behavior as they see fit.

Author: JohnTitor

library/panic_abort/src/lib.rs

@@ -37,12 +37,11 @@ pub unsafe fn __rust_start_panic(_payload: *mut &mut dyn BoxMeUp) -> u32 {
     abort();
 
     cfg_if::cfg_if! {
-        if #[cfg(unix)] {
+        if #[cfg(any(unix, target_os = "solid_asp3"))] {
             unsafe fn abort() -> ! {
                 libc::abort();
             }
         } else if #[cfg(any(target_os = "hermit",
-                            target_os = "solid_asp3",
                             all(target_vendor = "fortanix", target_env = "sgx")
         ))] {
             unsafe fn abort() -> ! {

library/std/src/sys/solid/abi/mod.rs

@@ -4,32 +4,6 @@ mod fs;
 pub mod sockets;
 pub use self::fs::*;
 
-#[inline(always)]
-pub fn breakpoint_program_exited(tid: usize) {
-    unsafe {
-        match () {
-            // SOLID_BP_PROGRAM_EXITED = 15
-            #[cfg(target_arch = "arm")]
-            () => core::arch::asm!("bkpt #15", in("r0") tid),
-            #[cfg(target_arch = "aarch64")]
-            () => core::arch::asm!("hlt #15", in("x0") tid),
-        }
-    }
-}
-
-#[inline(always)]
-pub fn breakpoint_abort() {
-    unsafe {
-        match () {
-            // SOLID_BP_CSABORT = 16
-            #[cfg(target_arch = "arm")]
-            () => core::arch::asm!("bkpt #16"),
-            #[cfg(target_arch = "aarch64")]
-            () => core::arch::asm!("hlt #16"),
-        }
-    }
-}
-
 // `solid_types.h`
 pub use super::itron::abi::{ER, ER_ID, E_TMOUT, ID};
 

library/std/src/sys/solid/mod.rs

@@ -76,20 +76,9 @@ pub fn decode_error_kind(code: i32) -> crate::io::ErrorKind {
     error::decode_error_kind(code)
 }
 
-#[inline(always)]
+#[inline]
 pub fn abort_internal() -> ! {
-    loop {
-        abi::breakpoint_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))]
-#[no_mangle]
-// NB. used by both libunwind and libpanic_abort
-pub extern "C" fn __rust_abort() {
-    abort_internal();
+    unsafe { libc::abort() }
 }
 
 pub fn hashmap_random_keys() -> (u64, u64) {

library/std/src/sys/solid/os.rs

@@ -11,7 +11,7 @@ use crate::path::{self, PathBuf};
 use crate::sys_common::rwlock::StaticRwLock;
 use crate::vec;
 
-use super::{abi, error, itron, memchr};
+use super::{error, itron, memchr};
 
 // `solid` directly maps `errno`s to μITRON error codes.
 impl itron::error::ItronError {
@@ -184,11 +184,8 @@ pub fn home_dir() -> Option<PathBuf> {
     None
 }
 
-pub fn exit(_code: i32) -> ! {
-    let tid = itron::task::try_current_task_id().unwrap_or(0);
-    loop {
-        abi::breakpoint_program_exited(tid as usize);
-    }
+pub fn exit(code: i32) -> ! {
+    rtabort!("exit({}) called", code);
 }
 
 pub fn getpid() -> u32 {