[PATCH 0/2] improve accuracy in riscv-pmp

[Ruibo Lu]

Based-on: 4329d049d5b8d4af71c6b399d64a6d1b98856318

Ruibo Lu (2):
  target/riscv: Remove redundant check in pmp_is_locked
  target/riscv: Optimize ambiguous local variable in pmp_hart_has_privs

 target/riscv/pmp.c | 25 ++++++++++---------------
 1 file changed, 10 insertions(+), 15 deletions(-)

-- 
2.41.0

>From 6780c552b3b4c1b8d6d8d5b17d4054c5f24ad062 Mon Sep 17 00:00:00 2001
From: Ruibo Lu <reaperlu@hust.edu.cn>
Date: Wed, 28 Jun 2023 11:07:33 +0800
Subject: [PATCH 1/2] target/riscv: Remove redundant check in pmp_is_locked

the check of top PMP is redundant and will not influence the return
value, so consider remove it

Signed-off-by: Ruibo Lu <reaperlu@hust.edu.cn>
---
 target/riscv/pmp.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 9d8db493e6..1a9279ba88 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -49,11 +49,6 @@ static inline int pmp_is_locked(CPURISCVState *env, uint32_t 
pmp_index)
         return 1;
     }
 
-    /* Top PMP has no 'next' to check */
-    if ((pmp_index + 1u) >= MAX_RISCV_PMPS) {
-        return 0;
-    }
-
     return 0;
 }
 
-- 
2.41.0


>From 7174d9fb96f5e5dcde41d74b4270216286b9bb3d Mon Sep 17 00:00:00 2001
From: Ruibo Lu <reaperlu@hust.edu.cn>
Date: Wed, 28 Jun 2023 11:19:38 +0800
Subject: [PATCH 2/2] target/riscv: Optimize ambiguous local variable in
 pmp_hart_has_privs

These two values represents whether start/end address is in pmp_range.
However, the type and name of them is ambiguous. This commit change the
name and type of them to improve code readability and accuracy.

Signed-off-by: Ruibo Lu <reaperlu@hust.edu.cn>
---
 target/riscv/pmp.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 1a9279ba88..aa573bab14 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -203,16 +203,16 @@ void pmp_update_rule_nums(CPURISCVState *env)
     }
 }
 
-static int pmp_is_in_range(CPURISCVState *env, int pmp_index,
+static bool pmp_is_in_range(CPURISCVState *env, int pmp_index,
                            target_ulong addr)
 {
-    int result = 0;
+    int result = false;
 
     if ((addr >= env->pmp_state.addr[pmp_index].sa) &&
         (addr <= env->pmp_state.addr[pmp_index].ea)) {
-        result = 1;
+        result = true;
     } else {
-        result = 0;
+        result = false;
     }
 
     return result;
@@ -287,8 +287,8 @@ bool pmp_hart_has_privs(CPURISCVState *env, target_ulong 
addr,
 {
     int i = 0;
     int pmp_size = 0;
-    target_ulong s = 0;
-    target_ulong e = 0;
+    bool sa_in = 0;
+    bool ea_in = 0;
 
     /* Short cut if no rules */
     if (0 == pmp_get_num_rules(env)) {
@@ -314,11 +314,11 @@ bool pmp_hart_has_privs(CPURISCVState *env, target_ulong 
addr,
      * from low to high
      */
     for (i = 0; i < MAX_RISCV_PMPS; i++) {
-        s = pmp_is_in_range(env, i, addr);
-        e = pmp_is_in_range(env, i, addr + pmp_size - 1);
+        sa_in = pmp_is_in_range(env, i, addr);
+        ea_in = pmp_is_in_range(env, i, addr + pmp_size - 1);
 
         /* partially inside */
-        if ((s + e) == 1) {
+        if (sa_in ^ ea_in) {
             qemu_log_mask(LOG_GUEST_ERROR,
                           "pmp violation - access is partially inside\n");
             *allowed_privs = 0;
@@ -339,7 +339,7 @@ bool pmp_hart_has_privs(CPURISCVState *env, target_ulong 
addr,
             (env->pmp_state.pmp[i].cfg_reg & PMP_WRITE) |
             ((env->pmp_state.pmp[i].cfg_reg & PMP_EXEC) >> 2);
 
-        if (((s + e) == 2) && (PMP_AMATCH_OFF != a_field)) {
+        if ((sa_in & ea_in) && (PMP_AMATCH_OFF != a_field)) {
             /*
              * If the PMP entry is not off and the address is in range,
              * do the priv check
-- 
2.41.0