[PATCH V2] riscv: correct pt_level name via pgtable_l5/4_enabled

[Song Shuai]

The pt_level uses CONFIG_PGTABLE_LEVELS to display page table names.
But if page mode is downgraded from kernel cmdline or restricted by
the hardware in 64BIT, it will give a wrong name.

Like, using no4lvl for sv39, ptdump named the 1G-mapping as "PUD"
that should be "PGD":

0xffffffd840000000-0xffffffd900000000    0x00000000c0000000         3G PUD     D A G . . W R V

So select "P4D/PUD" or "PGD" via pgtable_l5/4_enabled to correct it.

Fixes: e8a62cc26ddf ("riscv: Implement sv48 support")
Reviewed-by: Alexandre Ghiti <alexghiti at rivosinc.com>
Signed-off-by: Song Shuai <suagrfillet at gmail.com>
---
Changes since V1:
https://lore.kernel.org/linux-riscv/20230711105202.842408-1-suagrfillet@gmail.com/
- remove the reduntant #ifdef
- correct the Fixes tag and add Reviewed-by from Alex
---
 arch/riscv/mm/ptdump.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/riscv/mm/ptdump.c b/arch/riscv/mm/ptdump.c
index 20a9f991a6d7..e9090b38f811 100644
--- a/arch/riscv/mm/ptdump.c
+++ b/arch/riscv/mm/ptdump.c
@@ -384,6 +384,9 @@ static int __init ptdump_init(void)
 
 	kernel_ptd_info.base_addr = KERN_VIRT_START;
 
+	pg_level[1].name = pgtable_l5_enabled ? "P4D" : "PGD";
+	pg_level[2].name = pgtable_l4_enabled ? "PUD" : "PGD";
+
 	for (i = 0; i < ARRAY_SIZE(pg_level); i++)
 		for (j = 0; j < ARRAY_SIZE(pte_bits); j++)
 			pg_level[i].mask |= pte_bits[j].mask;
-- 
2.20.1