Fix static linker error caused by setjmp aarch64

src/header/setjmp/mod.rs

@@ -2,7 +2,9 @@
 //!
 //! See <https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/setjmp.h.html>.
 
-use core::arch::global_asm;
+use core::{arch::global_asm, ffi::c_int};
+
+use crate::header::signal::sigsetjmp;
 
 macro_rules! platform_specific {
     ($($rust_arch:expr,$c_arch:expr,$ext:expr;)+) => {
@@ -29,3 +31,15 @@ unsafe extern "C" {
     /// See <https://pubs.opengroup.org/onlinepubs/9799919799/functions/longjmp.html>.
     pub fn longjmp(jb: *mut u64, ret: i32);
 }
+
+#[cfg(target_arch = "aarch64")]
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn __relibc_unused_but_exist_to_avoid_linker_error_on_setjmp(arg: c_int) {
+    /// Workaround to https://www.openwall.com/lists/musl/2023/09/07/2
+    /// By keeping setjmp close to sigsetjmp in link time
+    let jb: *mut u64 = core::ptr::null_mut();
+    unsafe {
+        setjmp(jb);
+        sigsetjmp(jb, arg);
+    }
+}