arm64: entry: add missing noinstr

We intend that all the early exception handling code is marked as
`noinstr`, but we forgot this for __el0_error_handler_common(), which is
called before we have completed entry from user mode. If it were
instrumented, we could run into problems with RCU, lockdep, etc.

Mark it as `noinstr` to prevent this.

The few other functions in entry-common.c which do not have `noinstr` are
called once we've completed entry, and are safe to instrument.

Fixes: bb8e93a2 ("arm64: entry: convert SError handlers to C")
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20210714172801.16475-1-mark.rutland@arm.comSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/entry-common.c

@@ -604,7 +604,7 @@ asmlinkage void noinstr el0t_64_fiq_handler(struct pt_regs *regs)
 	__el0_fiq_handler_common(regs);
 }
 
-static void __el0_error_handler_common(struct pt_regs *regs)
+static void noinstr __el0_error_handler_common(struct pt_regs *regs)
 {
 	unsigned long esr = read_sysreg(esr_el1);