riscv: Fix kasan pud population

In sv48, the kasan inner regions are not aligned on PGDIR_SIZE and then
when we populate the kasan linear mapping region, we clear the kasan
vmalloc region which is in the same PGD.

Fix this by copying the content of the kasan early pud after allocating a
new PGD for the first time.

Fixes: e8a62cc2 ("riscv: Implement sv48 support")
Signed-off-by: NAlexandre Ghiti <alexandre.ghiti@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPalmer Dabbelt <palmer@rivosinc.com>

arch/riscv/mm/kasan_init.c

@@ -113,8 +113,11 @@ static void __init kasan_populate_pud(pgd_t *pgd,
 		base_pud = pt_ops.get_pud_virt(pfn_to_phys(_pgd_pfn(*pgd)));
 	} else {
 		base_pud = (pud_t *)pgd_page_vaddr(*pgd);
-		if (base_pud == lm_alias(kasan_early_shadow_pud))
+		if (base_pud == lm_alias(kasan_early_shadow_pud)) {
 			base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
+			memcpy(base_pud, (void *)kasan_early_shadow_pud,
+			       sizeof(pud_t) * PTRS_PER_PUD);
+		}
 	}
 
 	pudp = base_pud + pud_index(vaddr);