[PATCH v1 RFC Zisslpcfi 4/9] target/riscv: helper functions for forward and backward cfi

[Deepak Gupta <debug@rivosinc.com>]

Implementation for forward cfi and backward cfi needs helper function
to determine if currently fcfi and bcfi are enabled. Enable depends on
privilege mode and settings in sstatus/menvcfg/henvcfg/mseccfg CSRs.

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Signed-off-by: Kip Walker  <kip@rivosinc.com>
---
 target/riscv/cpu.h        |  2 ++
 target/riscv/cpu_helper.c | 51 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 18db61a06a..d14ea4f91d 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -568,6 +568,8 @@ bool riscv_cpu_virt_enabled(CPURISCVState *env);
 void riscv_cpu_set_virt_enabled(CPURISCVState *env, bool enable);
 bool riscv_cpu_two_stage_lookup(int mmu_idx);
 int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch);
+bool cpu_get_fcfien(CPURISCVState *env);
+bool cpu_get_bcfien(CPURISCVState *env);
 hwaddr riscv_cpu_get_phys_page_debug(CPUState *cpu, vaddr addr);
 G_NORETURN void  riscv_cpu_do_unaligned_access(CPUState *cs, vaddr addr,
                                                MMUAccessType access_type, int mmu_idx,
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 9a28816521..a397023840 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -30,6 +30,7 @@
 #include "sysemu/cpu-timers.h"
 #include "cpu_bits.h"
 #include "debug.h"
+#include "pmp.h"
 
 int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
 {
@@ -40,6 +41,56 @@ int riscv_cpu_mmu_index(CPURISCVState *env, bool ifetch)
 #endif
 }
 
+bool cpu_get_fcfien(CPURISCVState *env)
+{
+#ifdef CONFIG_USER_ONLY
+    return false;
+#else
+    /* no cfi extension, return false */
+    if (!env_archcpu(env)->cfg.ext_cfi) {
+        return false;
+    }
+
+    switch (env->priv) {
+    case PRV_U:
+        return (env->mstatus & MSTATUS_UFCFIEN) ? true : false;
+    case PRV_S:
+        return (env->menvcfg & MENVCFG_SFCFIEN) ? true : false;
+    case PRV_M:
+        return (env->mseccfg & MSECCFG_MFCFIEN) ? true : false;
+    default:
+        g_assert_not_reached();
+    }
+#endif
+}
+
+bool cpu_get_bcfien(CPURISCVState *env)
+{
+#ifdef CONFIG_USER_ONLY
+    return false;
+#else
+    /* no cfi extension, return false */
+    if (!env_archcpu(env)->cfg.ext_cfi) {
+        return false;
+    }
+
+    switch (env->priv) {
+    case PRV_U:
+        return (env->mstatus & MSTATUS_UBCFIEN) ? true : false;
+
+        /*
+         * no gating for back cfi in M/S mode. back cfi is always on for
+         * M/S mode
+         */
+    case PRV_S:
+    case PRV_M:
+        return true;
+    default:
+        g_assert_not_reached();
+    }
+#endif
+}
+
 void cpu_get_tb_cpu_state(CPURISCVState *env, target_ulong *pc,
                           target_ulong *cs_base, uint32_t *pflags)
 {
-- 
2.25.1