x86/mm: Randomize per-cpu entry area

mainline inclusion
from mainline-v6.2-rc1
commit 97e3d26b
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I6C6UC
CVE: CVE-2023-0597

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=97e3d26b5e5f371b3ee223d94dd123e6c442ba80



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

Seth found that the CPU-entry-area; the piece of per-cpu data that is
mapped into the userspace page-tables for kPTI is not subject to any
randomization -- irrespective of kASLR settings.

On x86_64 a whole P4D (512 GB) of virtual address space is reserved for
this structure, which is plenty large enough to randomize things a
little.

As such, use a straight forward randomization scheme that avoids
duplicates to spread the existing CPUs over the available space.

  [ bp: Fix le build. ]

Reported-by: Seth Jenkins <sethjenkins@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Confilict:
	arch/x86/mm/cpu_entry_area.c

	Use get_random_u32() instead of prandom_u32_max() in init_cea_offsets().

        With CONFIG_RANDOMIZE_BASE=y, KASLR use prandom_seed_state() init prandom seed before
        init_cea_offsets(). But when CONFIG_RANDOMIZE_BASE=n, prandom seed init after
        init_cea_offsets() cause cea is always 0.

        The patch d4150779("random32: use real rng for non-deterministic randomness")
        use get_random_u32() instead of prandom_u32() in prandom_u32_max()
        that make prandom_u32_max() don't need to wait prandom seed init().
	But the patch has many pre-patches that have not been merged,

	So,we adopt the current solution as a workaround. directly use
	get_random_u32() in init_cea_offsets() to simplify code.
Signed-off-by: Ke Liu <liuke94@huawei.com>
Reviewed-by: Wang Weiyang <wangweiyang2@huawei.com>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>