kaiser: tidied up kaiser_add/remove_mapping slightly

Yes, unmap_pud_range_nofree()'s declaration ought to be in a
header file really, but I'm not sure we want to use it anyway:
so for now just declare it inside kaiser_remove_mapping().
And there doesn't seem to be such a thing as unmap_p4d_range(),
even in a 5-level paging tree.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 0c68228f7b39c96cabd89bee3e1d6bd55926df80)
Orabug: 27333760
CVE: CVE-2017-5754
Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Kirtikar Kashyap <kirtikar.kashyap@oracle.com>

diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c
index 058d0886086bb99687846ea335a0d84b7f74e419..190371071a02ece50a2e6a897b3030b485ce027a 100644 (file)
--- a/arch/x86/mm/kaiser.c
+++ b/arch/x86/mm/kaiser.c
@@ -286,8 +286,7 @@ void __init kaiser_init(void)
                                  __PAGE_KERNEL);
 }
 
-extern void unmap_pud_range_nofree(pgd_t *pgd, unsigned long start, unsigned long end);
-// add a mapping to the shadow-mapping, and synchronize the mappings
+/* Add a mapping to the shadow mapping, and synchronize the mappings */
 int kaiser_add_mapping(unsigned long addr, unsigned long size, unsigned long flags)
 {
        return kaiser_add_user_map((const void *)addr, size, flags);
@@ -295,15 +294,13 @@ int kaiser_add_mapping(unsigned long addr, unsigned long size, unsigned long fla
 
 void kaiser_remove_mapping(unsigned long start, unsigned long size)
 {
+       extern void unmap_pud_range_nofree(pgd_t *pgd,
+                               unsigned long start, unsigned long end);
        unsigned long end = start + size;
        unsigned long addr;
 
        for (addr = start; addr < end; addr += PGDIR_SIZE) {
                pgd_t *pgd = native_get_shadow_pgd(pgd_offset_k(addr));
-               /*
-                * unmap_p4d_range() handles > P4D_SIZE unmaps,
-                * so no need to trim 'end'.
-                */
                unmap_pud_range_nofree(pgd, addr, end);
        }
 }