fault-injection: allow stacktrace filter for x86-64

This patchset allow fault injection to run on x86_64 and makes stacktrace
filter work as expected.  With this, we can test a device driver module
with fault injection more easily.


This patch (of 4):

FAULT_INJECTION_STACKTRACE_FILTER option was apparently disallowed on
x86_64 because of problems with the stack unwinder:

    commit 6d690dca
    Author: Akinobu Mita <akinobu.mita@gmail.com>
    Date:   Sat May 12 10:36:53 2007 -0700

        fault injection: disable stacktrace filter for x86-64

However, there is no problems whatsoever with this today. Let's allow
it again.

Link: https://lkml.kernel.org/r/20220817080332.1052710-1-weiyongjun1@huawei.com
Link: https://lkml.kernel.org/r/20220817080332.1052710-2-weiyongjun1@huawei.comSigned-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Isabella Basso <isabbasso@riseup.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/Kconfig.debug

@@ -1982,7 +1982,6 @@ config FAIL_SUNRPC
 config FAULT_INJECTION_STACKTRACE_FILTER
 	bool "stacktrace filter for fault-injection capabilities"
 	depends on FAULT_INJECTION_DEBUG_FS && STACKTRACE_SUPPORT
-	depends on !X86_64
 	select STACKTRACE
 	depends on FRAME_POINTER || MIPS || PPC || S390 || MICROBLAZE || ARM || ARC || X86
 	help