openbsd: incoporate remarks

- consolidate target_record_sp_limit and target_get_sp_limit functions
  for aarch64, powerpc, arm-ios and openbsd as there are all without
  segmented stacks (no need to duplicate functions).

- rename __load_self function to rust_load_self

- use a mutex inner load_self() as underline implementation is not thread-safe

src/libstd/sys/common/stack.rs

@@ -227,24 +227,14 @@ pub unsafe fn record_sp_limit(limit: uint) {
     }
 
     // aarch64 - FIXME(AARCH64): missing...
-    #[cfg(target_arch = "aarch64")]
-    unsafe fn target_record_sp_limit(_: uint) {
-    }
-
     // powerpc - FIXME(POWERPC): missing...
-    #[cfg(target_arch = "powerpc")]
-    unsafe fn target_record_sp_limit(_: uint) {
-    }
-
-
-    // iOS segmented stack is disabled for now, see related notes
-    #[cfg(all(target_arch = "arm", target_os = "ios"))] #[inline(always)]
-    unsafe fn target_record_sp_limit(_: uint) {
-    }
-
-    #[cfg(target_os = "openbsd")] #[inline(always)]
+    // arm-ios - iOS segmented stack is disabled for now, see related notes
+    // openbsd - segmented stack is disabled
+    #[cfg(any(target_arch = "aarch64",
+              target_arch = "powerpc",
+              all(target_arch = "arm", target_os = "ios"),
+              target_os = "openbsd"))]
     unsafe fn target_record_sp_limit(_: uint) {
-        // segmented stack is disabled
     }
 }
 
@@ -332,28 +322,18 @@ pub unsafe fn get_sp_limit() -> uint {
     }
 
     // aarch64 - FIXME(AARCH64): missing...
-    #[cfg(target_arch = "aarch64")]
-    unsafe fn target_get_sp_limit() -> uint {
-        1024
-    }
-
-    // powepc - FIXME(POWERPC): missing...
-    #[cfg(target_arch = "powerpc")]
-    unsafe fn target_get_sp_limit() -> uint {
-        1024
-    }
-
-    // iOS doesn't support segmented stacks yet. This function might
-    // be called by runtime though so it is unsafe to mark it as
-    // unreachable, let's return a fixed constant.
-    #[cfg(all(target_arch = "arm", target_os = "ios"))] #[inline(always)]
-    unsafe fn target_get_sp_limit() -> uint {
-        1024
-    }
-
-    #[cfg(target_os = "openbsd")] #[inline(always)]
+    // powerpc - FIXME(POWERPC): missing...
+    // arm-ios - iOS doesn't support segmented stacks yet.
+    // openbsd - OpenBSD doesn't support segmented stacks.
+    //
+    // This function might be called by runtime though
+    // so it is unsafe to unreachable, let's return a fixed constant.
+    #[cfg(any(target_arch = "aarch64",
+              target_arch = "powerpc",
+              all(target_arch = "arm", target_os = "ios"),
+              target_os = "openbsd"))]
+    #[inline(always)]
     unsafe fn target_get_sp_limit() -> uint {
-        // segmented stack is disabled
         1024
     }
 }

src/libstd/sys/unix/os.rs

@@ -217,11 +217,18 @@ pub fn load_self() -> Option<Vec<u8>> {
 
 #[cfg(target_os = "openbsd")]
 pub fn load_self() -> Option<Vec<u8>> {
+    use sync::{StaticMutex, MUTEX_INIT};
+
+    static LOCK: StaticMutex = MUTEX_INIT;
+
     extern {
-        fn __load_self() -> *const c_char;
+        fn rust_load_self() -> *const c_char;
     }
+
+    let _guard = LOCK.lock();
+
     unsafe {
-        let v = __load_self();
+        let v = rust_load_self();
         if v.is_null() {
             None
         } else {

src/rt/rust_builtin.c

@@ -204,7 +204,7 @@ int *__dfly_error(void) { return __error(); }
 #include <sys/sysctl.h>
 #include <limits.h>
 
-const char * __load_self() {
+const char * rust_load_self() {
     static char *self = NULL;
 
     if (self == NULL) {