x86/kasan: Extend KASAN to support 5-level paging

This patch bring support for a non-folded additional page table level.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170330080731.65421-7-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 3d1059db6bf62ede5691ca8f0c01f1792958925b..47efdcfe711313c2d719e645d6dafbf0fdea3e7c 100644 (file)
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -55,8 +55,18 @@ static void __init kasan_map_early_shadow(pgd_t *pgd)
        unsigned long end = KASAN_SHADOW_END;
 
        for (i = pgd_index(start); start < end; i++) {
-               pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud)
-                               | _KERNPG_TABLE);
+               switch (CONFIG_PGTABLE_LEVELS) {
+               case 4:
+                       pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud) |
+                                       _KERNPG_TABLE);
+                       break;
+               case 5:
+                       pgd[i] = __pgd(__pa_nodebug(kasan_zero_p4d) |
+                                       _KERNPG_TABLE);
+                       break;
+               default:
+                       BUILD_BUG();
+               }
                start += PGDIR_SIZE;
        }
 }
@@ -84,6 +94,7 @@ void __init kasan_early_init(void)
        pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL;
        pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
        pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
+       p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
 
        for (i = 0; i < PTRS_PER_PTE; i++)
                kasan_zero_pte[i] = __pte(pte_val);
@@ -94,6 +105,9 @@ void __init kasan_early_init(void)
        for (i = 0; i < PTRS_PER_PUD; i++)
                kasan_zero_pud[i] = __pud(pud_val);
 
+       for (i = 0; CONFIG_PGTABLE_LEVELS >= 5 && i < PTRS_PER_P4D; i++)
+               kasan_zero_p4d[i] = __p4d(p4d_val);
+
        kasan_map_early_shadow(early_level4_pgt);
        kasan_map_early_shadow(init_level4_pgt);
 }