[qemu] target/riscv: Add check for 16-bit aligned PC for different priv versions.

Commit Message

~yuming March 13, 2025, 6:07 a.m. UTC

From: Yu-Ming Chang <[e-mail]>

For privilege version 1.12 or newer, C always implies Zca. We can only
check ext_zca to allow 16-bit aligned PC addresses. For older privilege
versions, we only check C.

Signed-off-by: Yu-Ming Chang <[e-mail]>
---
 target/riscv/cpu.h                      | 12 ++++++++++++
 target/riscv/insn_trans/trans_rvi.c.inc |  8 ++++++--
 target/riscv/op_helper.c                |  8 ++++++--
 target/riscv/translate.c                |  4 +++-
 4 files changed, 27 insertions(+), 5 deletions(-)

Patch

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 7de19b4183..51e49e03de 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -765,6 +765,18 @@  static inline RISCVMXL riscv_cpu_sxl(CPURISCVState *env)
 }
 #endif
 
+static inline bool riscv_cpu_allow_16bit_insn(const RISCVCPUConfig *cfg,
+                                              target_long priv_ver,
+                                              uint32_t misa_ext)
+{
+    /* In priv spec version 1.12 or newer, C always implies Zca */
+    if (priv_ver >= PRIV_VERSION_1_12_0) {
+        return cfg->ext_zca;
+    } else {
+        return misa_ext & RVC;
+    }
+}
+
 /*
  * Encode LMUL to lmul as follows:
  *     LMUL    vlmul    lmul
diff --git a/target/riscv/insn_trans/trans_rvi.c.inc b/target/riscv/insn_trans/trans_rvi.c.inc
index b55f56a5eb..b9c7160468 100644
--- a/target/riscv/insn_trans/trans_rvi.c.inc
+++ b/target/riscv/insn_trans/trans_rvi.c.inc
@@ -151,7 +151,9 @@  static bool trans_jalr(DisasContext *ctx, arg_jalr *a)
         tcg_gen_ext32s_tl(target_pc, target_pc);
     }
 
-    if (!has_ext(ctx, RVC) && !ctx->cfg_ptr->ext_zca) {
+    if (!riscv_cpu_allow_16bit_insn(ctx->cfg_ptr,
+                                    ctx->priv_ver,
+                                    ctx->misa_ext)) {
         TCGv t0 = tcg_temp_new();
 
         misaligned = gen_new_label();
@@ -300,7 +302,9 @@  static bool gen_branch(DisasContext *ctx, arg_b *a, TCGCond cond)
 
     gen_set_label(l); /* branch taken */
 
-    if (!has_ext(ctx, RVC) && !ctx->cfg_ptr->ext_zca &&
+    if (!riscv_cpu_allow_16bit_insn(ctx->cfg_ptr,
+                                    ctx->priv_ver,
+                                    ctx->misa_ext) &&
         (a->imm & 0x3)) {
         /* misaligned */
         TCGv target_pc = tcg_temp_new();
diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
index 0d4220ba93..72dc48e58d 100644
--- a/target/riscv/op_helper.c
+++ b/target/riscv/op_helper.c
@@ -279,7 +279,9 @@  target_ulong helper_sret(CPURISCVState *env)
     }
 
     target_ulong retpc = env->sepc;
-    if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
+    if (!riscv_cpu_allow_16bit_insn(&env_archcpu(env)->cfg,
+                                    env->priv_ver,
+                                    env->misa_ext) && (retpc & 0x3)) {
         riscv_raise_exception(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
     }
 
@@ -357,7 +359,9 @@  static void check_ret_from_m_mode(CPURISCVState *env, target_ulong retpc,
         riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, GETPC());
     }
 
-    if (!riscv_has_ext(env, RVC) && (retpc & 0x3)) {
+    if (!riscv_cpu_allow_16bit_insn(&env_archcpu(env)->cfg,
+                                    env->priv_ver,
+                                    env->misa_ext) && (retpc & 0x3)) {
         riscv_raise_exception(env, RISCV_EXCP_INST_ADDR_MIS, GETPC());
     }
 
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index eaa5d86eae..d6651f244f 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -606,7 +606,9 @@  static void gen_jal(DisasContext *ctx, int rd, target_ulong imm)
     TCGv succ_pc = dest_gpr(ctx, rd);
 
     /* check misaligned: */
-    if (!has_ext(ctx, RVC) && !ctx->cfg_ptr->ext_zca) {
+    if (!riscv_cpu_allow_16bit_insn(ctx->cfg_ptr,
+                                    ctx->priv_ver,
+                                    ctx->misa_ext)) {
         if ((imm & 0x3) != 0) {
             TCGv target_pc = tcg_temp_new();
             gen_pc_plus_diff(target_pc, ctx, imm);