xen: unexport __init-annotated xen_xlate_map_ballooned_pages()

stable inclusion
from stable-v5.10.122
commit be9581f4fda795aa0e18cdc333efc1e447e1a55c
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5W6OE

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=be9581f4fda795aa0e18cdc333efc1e447e1a55c

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

[ Upstream commit dbac14a5 ]

EXPORT_SYMBOL and __init is a bad combination because the .init.text
section is freed up after the initialization. Hence, modules cannot
use symbols annotated __init. The access to a freed symbol may end up
with kernel panic.

modpost used to detect it, but it has been broken for a decade.

Recently, I fixed modpost so it started to warn it again, then this
showed up in linux-next builds.

There are two ways to fix it:

  - Remove __init
  - Remove EXPORT_SYMBOL

I chose the latter for this case because none of the in-tree call-sites
(arch/arm/xen/enlighten.c, arch/x86/xen/grant-table.c) is compiled as
modular.

Fixes: 243848fc ("xen/grant-table: Move xlated_setup_gnttab_pages to common place")
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: NOleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Acked-by: NStefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20220606045920.4161881-1-masahiroy@kernel.orgSigned-off-by: NJuergen Gross <jgross@suse.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>

drivers/xen/xlate_mmu.c

@@ -261,7 +261,6 @@ int __init xen_xlate_map_ballooned_pages(xen_pfn_t **gfns, void **virt,
 
 	return 0;
 }
-EXPORT_SYMBOL_GPL(xen_xlate_map_ballooned_pages);
 
 struct remap_pfn {
 	struct mm_struct *mm;