[PATCH v4] x86/mm/kasan: Teach KASAN about the cpu_entry_area

[Andrey Ryabinin]

From: Andy Lutomirski <l...@kernel.org>

The cpu_entry_area will contain stacks.  Make sure that KASAN has
appropriate shadow mappings for them.

Cc: Alexander Potapenko <gli...@google.com>
Cc: Dmitry Vyukov <dvyu...@google.com>
Cc: kasan-...@googlegroups.com
Signed-off-by: Andy Lutomirski <l...@kernel.org>
Signed-off-by: Andrey Ryabinin <aryabi...@virtuozzo.com>
---
 arch/x86/mm/kasan_init_64.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index 99dfed6dfef8..9ec70d780f1f 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -277,6 +277,7 @@ void __init kasan_early_init(void)
 void __init kasan_init(void)
 {
        int i;
+       void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
 
 #ifdef CONFIG_KASAN_INLINE
        register_die_notifier(&kasan_die_notifier);
@@ -329,8 +330,23 @@ void __init kasan_init(void)
                              (unsigned long)kasan_mem_to_shadow(_end),
                              early_pfn_to_nid(__pa(_stext)));
 
+       shadow_cpu_entry_begin = (void 
*)__fix_to_virt(FIX_CPU_ENTRY_AREA_BOTTOM);
+       shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
+       shadow_cpu_entry_begin = (void *)round_down((unsigned 
long)shadow_cpu_entry_begin,
+                                               PAGE_SIZE);
+
+       shadow_cpu_entry_end = (void *)(__fix_to_virt(FIX_CPU_ENTRY_AREA_TOP) + 
PAGE_SIZE);
+       shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
+       shadow_cpu_entry_end = (void *)round_up((unsigned 
long)shadow_cpu_entry_end,
+                                       PAGE_SIZE);
+
        kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
-                       (void *)KASAN_SHADOW_END);
+                                  shadow_cpu_entry_begin);
+
+       kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
+                             (unsigned long)shadow_cpu_entry_end, 0);
+
+       kasan_populate_zero_shadow(shadow_cpu_entry_end, (void 
*)KASAN_SHADOW_END);
 
        load_cr3(init_top_pgt);
        __flush_tlb_all();
-- 
2.13.6