exo2: implement the atmosphere extension mappers

exosphere2/program/source/secmon_spinlock.s

@@ -0,0 +1,44 @@
+/*
+ * Copyright (c) 2018-2020 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+.section    .text._ZN3ams6secmon15AcquireSpinLockERj, "ax", %progbits
+.align      4
+.global     _ZN3ams6secmon15AcquireSpinLockERj
+_ZN3ams6secmon15AcquireSpinLockERj:
+    /* Prepare to try to take the spinlock. */
+    mov w1, #1
+    sevl
+    prfm pstl1keep, [x0]
+
+1:  /* Repeatedly try to take the lock. */
+    wfe
+    ldaxr w2, [x0]
+    cbnz  w2, 1b
+    stxr  w2, w1, [x0]
+    cbnz  w2, 1b
+
+    /* Return. */
+    ret
+
+.section    .text._ZN3ams6secmon15ReleaseSpinLockERj, "ax", %progbits
+.align      4
+.global     _ZN3ams6secmon15ReleaseSpinLockERj
+_ZN3ams6secmon15ReleaseSpinLockERj:
+    /* Release the spinlock. */
+    stlr wzr, [x0]
+
+    /* Return. */
+    ret