[PATCH] target/riscv: Add asserts for out-of-bound access

[Atish Patra <atishp@rivosinc.com>]

Coverity complained about the possible out-of-bounds access with
counter_virt/counter_virt_prev because these two arrays are
accessed with privilege mode. However, these two arrays are accessed
only when virt is enabled. Thus, the privilege mode can't be M mode.

Add the asserts anyways to detect any wrong usage of these arrays
in the future.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
The lore discussion can be found here
https://lore.kernel.org/all/CAHBxVyGQHBobpf71o4Qp51iQGXKBh0Ajup=e_a95xdLF==V_WQ@mail.gmail.com/
---
 target/riscv/pmu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/riscv/pmu.c b/target/riscv/pmu.c
index 3cc0b3648cad..e05ab067d2f2 100644
--- a/target/riscv/pmu.c
+++ b/target/riscv/pmu.c
@@ -204,6 +204,7 @@ static void riscv_pmu_icount_update_priv(CPURISCVState *env,
     }
 
     if (env->virt_enabled) {
+        g_assert(env->priv <= PRV_S);
         counter_arr = env->pmu_fixed_ctrs[1].counter_virt;
         snapshot_prev = env->pmu_fixed_ctrs[1].counter_virt_prev;
     } else {
@@ -212,6 +213,7 @@ static void riscv_pmu_icount_update_priv(CPURISCVState *env,
     }
 
     if (new_virt) {
+        g_assert(newpriv <= PRV_S);
         snapshot_new = env->pmu_fixed_ctrs[1].counter_virt_prev;
     } else {
         snapshot_new = env->pmu_fixed_ctrs[1].counter_prev;
@@ -242,6 +244,7 @@ static void riscv_pmu_cycle_update_priv(CPURISCVState *env,
     }
 
     if (env->virt_enabled) {
+        g_assert(env->priv <= PRV_S);
         counter_arr = env->pmu_fixed_ctrs[0].counter_virt;
         snapshot_prev = env->pmu_fixed_ctrs[0].counter_virt_prev;
     } else {
@@ -250,6 +253,7 @@ static void riscv_pmu_cycle_update_priv(CPURISCVState *env,
     }
 
     if (new_virt) {
+        g_assert(newpriv <= PRV_S);
         snapshot_new = env->pmu_fixed_ctrs[0].counter_virt_prev;
     } else {
         snapshot_new = env->pmu_fixed_ctrs[0].counter_prev;

---
base-commit: daff9f7f7a457f78ce455e6abf19c2a37dfe7630
change-id: 20240723-fixes-439b929bfbc8
--
Regards,
Atish patra