Replace manual bit manipulation with ROUND_DOWN() macro for
better readability. The behavior remains unchanged.

Signed-off-by: Jay Chang <jay.chang@sifive.com>
---
 target/riscv/pmp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 01b337f529..7ac5cbfae2 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -235,8 +235,9 @@ void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
     case PMP_AMATCH_TOR:
         /* Bits pmpaddr[G-1:0] do not affect the TOR address-matching logic. */
         if (g >= 1) {
-            prev_addr &= ~((1ULL << g) - 1ULL);
-            this_addr &= ~((1ULL << g) - 1ULL);
+            target_ulong granule = 1ULL << g;
+            prev_addr = ROUND_DOWN(prev_addr, granule);
+            this_addr = ROUND_DOWN(this_addr, granule);
         }
         if (prev_addr >= this_addr) {
             sa = ea = 0u;
@@ -625,7 +626,8 @@ target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index)
         case PMP_AMATCH_TOR:
             /* Bit [g-1:0] read all zero */
             if (g >= 1 && g < TARGET_LONG_BITS) {
-                val &= ~((1ULL << g) - 1ULL);
+                target_ulong granule = 1ULL << g;
+                val = ROUND_DOWN(val, granule);
             }
             break;
         case PMP_AMATCH_NAPOT:
-- 
2.48.1