powerpc/kasan: Fix shadow pages allocation failure

Doing kasan pages allocation in MMU_init is too early, kernel doesn't
have access yet to the entire memory space and memblock_alloc() fails
when the kernel is a bit big.

Do it from kasan_init() instead.

Fixes: 2edb16ef ("powerpc/32: Add KASAN support")
Cc: stable@vger.kernel.org
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c24163ee5d5f8cdf52fefa45055ceb35435b8f15.1589866984.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/kasan.h

@@ -27,12 +27,10 @@
 
 #ifdef CONFIG_KASAN
 void kasan_early_init(void);
-void kasan_mmu_init(void);
 void kasan_init(void);
 void kasan_late_init(void);
 #else
 static inline void kasan_init(void) { }
-static inline void kasan_mmu_init(void) { }
 static inline void kasan_late_init(void) { }
 #endif
 

arch/powerpc/mm/init_32.c

@@ -170,8 +170,6 @@ void __init MMU_init(void)
 	btext_unmap();
 #endif
 
-	kasan_mmu_init();
-
 	setup_kup();
 
 	/* Shortly after that, the entire linear mapping will be available */

arch/powerpc/mm/kasan/kasan_init_32.c

@@ -131,7 +131,7 @@ static void __init kasan_unmap_early_shadow_vmalloc(void)
 	flush_tlb_kernel_range(k_start, k_end);
 }
 
-void __init kasan_mmu_init(void)
+static void __init kasan_mmu_init(void)
 {
 	int ret;
 	struct memblock_region *reg;
@@ -159,6 +159,8 @@ void __init kasan_mmu_init(void)
 
 void __init kasan_init(void)
 {
+	kasan_mmu_init();
+
 	kasan_remap_early_shadow_ro();
 
 	clear_page(kasan_early_shadow_page);