Revert "arm64: Stash shadow stack pointer in the task struct on interrupt"

This reverts commit 3f225f29c6 which is
commit 59b37fe52f49955791a460752c37145f1afdcad1 upstream.

It breaks some test systems, so obviously the backport to 5.10.y wasn't
quite correct :(

Revert it for now until this can be figured out better.

Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I1071c357225a8b41f15767a27b5c56cf94d7a5f7

arch/arm64/kernel/entry.S

@@ -530,7 +530,9 @@ SYM_CODE_END(__swpan_exit_el0)
 
 	.macro	irq_stack_entry
 	mov	x19, sp			// preserve the original sp
-	scs_save tsk			// preserve the original shadow stack
+#ifdef CONFIG_SHADOW_CALL_STACK
+	mov	x24, scs_sp		// preserve the original shadow stack
+#endif
 
 	/*
 	 * Compare sp with the base of the task stack.
@@ -564,7 +566,9 @@ SYM_CODE_END(__swpan_exit_el0)
 	 */
 	.macro	irq_stack_exit
 	mov	sp, x19
-	scs_load_current
+#ifdef CONFIG_SHADOW_CALL_STACK
+	mov	scs_sp, x24
+#endif
 	.endm
 
 /* GPRs used by entry code */