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")
Fixes: d2a91cef ("powerpc/kasan: Fix shadow pages allocation failure")
Cc: stable@vger.kernel.org
Reported-by: Erhard F. <erhard_f@mailbox.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=208181
Link: https://lore.kernel.org/r/63048fcea8a1c02f75429ba3152f80f7853f87fc.1593690707.git.christophe.leroy@csgroup.eu

arch/powerpc/mm/kasan/kasan_init_32.c

@@ -120,11 +120,24 @@ static void __init kasan_unmap_early_shadow_vmalloc(void)
 void __init kasan_mmu_init(void)
 {
 	int ret;
+
+	if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE) ||
+	    IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
+		ret = kasan_init_shadow_page_tables(KASAN_SHADOW_START, KASAN_SHADOW_END);
+
+		if (ret)
+			panic("kasan: kasan_init_shadow_page_tables() failed");
+	}
+}
+
+void __init kasan_init(void)
+{
 	struct memblock_region *reg;
 
 	for_each_memblock(memory, reg) {
 		phys_addr_t base = reg->base;
 		phys_addr_t top = min(base + reg->size, total_lowmem);
+		int ret;
 
 		if (base >= top)
 			continue;
@@ -134,18 +147,6 @@ void __init kasan_mmu_init(void)
 			panic("kasan: kasan_init_region() failed");
 	}
 
-	if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE) ||
-	    IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
-		ret = kasan_init_shadow_page_tables(KASAN_SHADOW_START, KASAN_SHADOW_END);
-
-		if (ret)
-			panic("kasan: kasan_init_shadow_page_tables() failed");
-	}
-
-}
-
-void __init kasan_init(void)
-{
 	kasan_remap_early_shadow_ro();
 
 	clear_page(kasan_early_shadow_page);