[patch 10/60] x86/kasan/64: Teach KASAN about the cpu_entry_area

[Thomas Gleixner]

From: Andy Lutomirski <luto@xxxxxxxxxx>

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

Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: kasan-dev@xxxxxxxxxxxxxxxx
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/8407adf9126440d6467dade88fdb3e3b75fc1019.1511497875.git.luto@xxxxxxxxxx

---
 arch/x86/mm/kasan_init_64.c |   18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

--- 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();