Add longjmp support for Thumb-2

When a Thumb-2 kernel is being used, then longjmp must be implemented
using the Thumb-2 instruction set in module/lua/setjmp/setjmp_arm.S.

Original-patch-by: @jsrlabs
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue openzfs#9957

module/lua/setjmp/setjmp_arm.S

@@ -31,12 +31,19 @@
 
 #if defined(__arm__) && !defined(__aarch64__)
 
+#if defined(__thumb2__)
+#define	_FUNC_MODE	.code 16; .thumb_func
+#else
+#define	_FUNC_MODE	.code 32
+#endif
+
 #define	ENTRY(x) \
 	.text; \
+	.syntax unified; \
 	.align 2; \
 	.global x; \
 	.type x,#function; \
-	.code 32; \
+	_FUNC_MODE; \
 x:
 
 #define	END(x) \
@@ -49,13 +56,23 @@ x:
  * setjump + longjmp
  */
 ENTRY(setjmp)
+#if defined(__thumb2__)
+	mov	ip, sp
+	stmia	r0, {r4-r12,r14}
+#else
 	stmia	r0, {r4-r14}
+#endif
 	mov	r0, #0x00000000
 	RET
 END(setjmp)
 
 ENTRY(longjmp)
+#if defined(__thumb2__)
+	ldmia	r0, {r4-r12,r14}
+	mov	sp, ip
+#else
 	ldmia	r0, {r4-r14}
+#endif
 	mov	r0, #0x00000001
 	RET
 END(longjmp)