arm64: factor insn read out of call_undef_hook()

stable inclusion
from stable-v5.10.199
commit 15e964971ff701c661936aa6103d51a895f32e24
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I65RG3?from=project-issue
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=15e964971ff701c661936aa6103d51a895f32e24



-------------------------------------------------

commit dbfbd87e upstream.

Subsequent patches will rework EL0 UNDEF handling, removing the need for
struct undef_hook and call_undef_hook. In preparation for those changes,
this patch factors the logic for reading user instructions out of
call_undef_hook() and into a new user_insn_read() helper, matching the
style of the existing aarch64_insn_read() helper used for reading kernel
instructions.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20221019144123.612388-5-mark.rutland@arm.com


Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>