arm64: entry: Allow the trampoline text to occupy multiple pages

stable inclusion
from stable-v4.19.236
commit 22fdfcf1c2cea8e6dc383d46cbbe59d476d24a96
category: bugfix
bugzilla: 186460, https://gitee.com/src-openeuler/kernel/issues/I53MHA


CVE: CVE-2022-23960

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

commit a9c406e6 upstream.

Adding a second set of vectors to .entry.tramp.text will make it
larger than a single 4K page.

Allow the trampoline text to occupy up to three pages by adding two
more fixmap slots. Previous changes to tramp_valias allowed it to reach
beyond a single page.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jiahao <chenjiahao16@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Liao Chang <liaochang1@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>