riscv: Check the virtual alignment before choosing a map size

We used to only check the alignment of the physical address to decide
which mapping would fit for a certain region of the linear mapping, but
it is not enough since the virtual address must also be aligned, so check
that too.

Fixes: 3335068 ("riscv: Use PUD/P4D/PGD pages for the linear mapping")
Reported-by: Song Shuai <[email protected]>
Link: https://lore.kernel.org/linux-riscv/[email protected]/
Signed-off-by: Alexandre Ghiti <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>

Author: Alexandre Ghiti

arch/riscv/mm/init.c

@@ -660,18 +660,19 @@ void __init create_pgd_mapping(pgd_t *pgdp,
 	create_pgd_next_mapping(nextp, va, pa, sz, prot);
 }
 
-static uintptr_t __init best_map_size(phys_addr_t base, phys_addr_t size)
+static uintptr_t __init best_map_size(phys_addr_t pa, uintptr_t va,
+				      phys_addr_t size)
 {
-	if (!(base & (PGDIR_SIZE - 1)) && size >= PGDIR_SIZE)
+	if (!(pa & (PGDIR_SIZE - 1)) && !(va & (PGDIR_SIZE - 1)) && size >= PGDIR_SIZE)
 		return PGDIR_SIZE;
 
-	if (!(base & (P4D_SIZE - 1)) && size >= P4D_SIZE)
+	if (!(pa & (P4D_SIZE - 1)) && !(va & (P4D_SIZE - 1)) && size >= P4D_SIZE)
 		return P4D_SIZE;
 
-	if (!(base & (PUD_SIZE - 1)) && size >= PUD_SIZE)
+	if (!(pa & (PUD_SIZE - 1)) && !(va & (PUD_SIZE - 1)) && size >= PUD_SIZE)
 		return PUD_SIZE;
 
-	if (!(base & (PMD_SIZE - 1)) && size >= PMD_SIZE)
+	if (!(pa & (PMD_SIZE - 1)) && !(va & (PMD_SIZE - 1)) && size >= PMD_SIZE)
 		return PMD_SIZE;
 
 	return PAGE_SIZE;
@@ -1177,7 +1178,7 @@ static void __init create_linear_mapping_range(phys_addr_t start,
 	for (pa = start; pa < end; pa += map_size) {
 		va = (uintptr_t)__va(pa);
 		map_size = fixed_map_size ? fixed_map_size :
-					    best_map_size(pa, end - pa);
+					    best_map_size(pa, va, end - pa);
 
 		create_pgd_mapping(swapper_pg_dir, va, pa, map_size,
 				   pgprot_from_va(va));