kasan: arm64: fix pcpu_page_first_chunk crash with KASAN_VMALLOC

With KASAN_VMALLOC and NEED_PER_CPU_PAGE_FIRST_CHUNK the kernel crashes:

  Unable to handle kernel paging request at virtual address ffff7000028f2000
  ...
  swapper pgtable: 64k pages, 48-bit VAs, pgdp=0000000042440000
  [ffff7000028f2000] pgd=000000063e7c0003, p4d=000000063e7c0003, pud=000000063e7c0003, pmd=000000063e7b0003, pte=0000000000000000
  Internal error: Oops: 96000007 [#1] PREEMPT SMP
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 5.13.0-rc4-00003-gc6e6e28f3f30-dirty torvalds#62
  Hardware name: linux,dummy-virt (DT)
  pstate: 200000c5 (nzCv daIF -PAN -UAO -TCO BTYPE=--)
  pc : kasan_check_range+0x90/0x1a0
  lr : memcpy+0x88/0xf4
  sp : ffff80001378fe20
  ...
  Call trace:
   kasan_check_range+0x90/0x1a0
   pcpu_page_first_chunk+0x3f0/0x568
   setup_per_cpu_areas+0xb8/0x184
   start_kernel+0x8c/0x328

The vm area used in vm_area_register_early() has no kasan shadow memory,
Let's add a new kasan_populate_early_vm_area_shadow() function to
populate the vm area shadow memory to fix the issue.

[[email protected]: fix redefinition of 'kasan_populate_early_vm_area_shadow']
  Link: https://lkml.kernel.org/r/[email protected]

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: Marco Elver <[email protected]>		[KASAN]
Acked-by: Andrey Konovalov <[email protected]>	[KASAN]
Acked-by: Catalin Marinas <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

arch/arm64/mm/kasan_init.c

@@ -287,6 +287,22 @@ static void __init kasan_init_depth(void)
 	init_task.kasan_depth = 0;
 }
 
+#ifdef CONFIG_KASAN_VMALLOC
+void __init kasan_populate_early_vm_area_shadow(void *start, unsigned long size)
+{
+	unsigned long shadow_start, shadow_end;
+
+	if (!is_vmalloc_or_module_addr(start))
+		return;
+
+	shadow_start = (unsigned long)kasan_mem_to_shadow(start);
+	shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
+	shadow_end = (unsigned long)kasan_mem_to_shadow(start + size);
+	shadow_end = ALIGN(shadow_end, PAGE_SIZE);
+	kasan_map_populate(shadow_start, shadow_end, NUMA_NO_NODE);
+}
+#endif
+
 void __init kasan_init(void)
 {
 	kasan_init_shadow();

include/linux/kasan.h

@@ -436,6 +436,8 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
 			   unsigned long free_region_start,
 			   unsigned long free_region_end);
 
+void kasan_populate_early_vm_area_shadow(void *start, unsigned long size);
+
 #else /* CONFIG_KASAN_VMALLOC */
 
 static inline int kasan_populate_vmalloc(unsigned long start,
@@ -453,6 +455,10 @@ static inline void kasan_release_vmalloc(unsigned long start,
 					 unsigned long free_region_start,
 					 unsigned long free_region_end) {}
 
+static inline void kasan_populate_early_vm_area_shadow(void *start,
+						       unsigned long size)
+{ }
+
 #endif /* CONFIG_KASAN_VMALLOC */
 
 #if (defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)) && \

mm/kasan/shadow.c

@@ -254,6 +254,11 @@ core_initcall(kasan_memhotplug_init);
 
 #ifdef CONFIG_KASAN_VMALLOC
 
+void __init __weak kasan_populate_early_vm_area_shadow(void *start,
+						       unsigned long size)
+{
+}
+
 static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr,
 				      void *unused)
 {

mm/vmalloc.c

@@ -2291,6 +2291,7 @@ void __init vm_area_register_early(struct vm_struct *vm, size_t align)
 	vm->addr = (void *)addr;
 	vm->next = *p;
 	*p = vm;
+	kasan_populate_early_vm_area_shadow(vm->addr, vm->size);
 }
 
 static void vmap_init_free_space(void)