x86/entry: Enable random_kstack_offset support

mainline inclusion
from mainline-v5.13-rc1
commit fe950f60
category: featrue
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YQ6Z
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=fe950f6020338c8ac668ef823bb692d36b7542a2



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Allow for a randomized stack offset on a per-syscall basis, with roughly
5-6 bits of entropy, depending on compiler and word size. Since the
method of offsetting uses macros, this cannot live in the common entry
code (the stack offset needs to be retained for the life of the syscall,
which means it needs to happen at the actual entry point).

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210401232347.2791257-5-keescook@chromium.org


Signed-off-by: Yi Yang <yiyang13@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: GONG Ruiqi <gongruiqi1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>