From 578c41ceb73bdf9d97f23c9e0342f8d027c08e77 Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Sat, 8 Nov 2025 15:41:42 +0100
Subject: ARM64: Enable unaligned accesses if indicated by the toolchain.

If you get a crash in jit_init() then you need to fix your toolchain.
---
 src/lib_jit.c | 9 +++++++++
 1 file changed, 9 insertions(+)

(limited to 'src/lib_jit.c')

diff --git a/src/lib_jit.c b/src/lib_jit.c
index 1b74d957..0f75c5ac 100644
--- a/src/lib_jit.c
+++ b/src/lib_jit.c
@@ -723,7 +723,16 @@ static void jit_init(lua_State *L)
   jit_State *J = L2J(L);
   J->flags = jit_cpudetect() | JIT_F_ON | JIT_F_OPT_DEFAULT;
   memcpy(J->param, jit_param_default, sizeof(J->param));
+#if LJ_TARGET_UNALIGNED
+  G(L)->tmptv.u64 = U64x(0000504d,4d500000);
+#endif
   lj_dispatch_update(G(L));
+#if LJ_TARGET_UNALIGNED
+  /* If you get a crash below then your toolchain indicates unaligned
+  ** accesses are OK, but your kernel disagrees. I.e. fix your toolchain.
+  */
+  if (*(uint32_t *)((char *)&G(L)->tmptv + 2) != 0x504d4d50u) L->top = NULL;
+#endif
 }
 #endif
 
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