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Re: [PATCH v11 2/6] target/riscv: Simplify counter predicate function


From: Weiwei Li
Subject: Re: [PATCH v11 2/6] target/riscv: Simplify counter predicate function
Date: Wed, 27 Jul 2022 16:34:31 +0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0


在 2022/7/27 下午2:49, Atish Patra 写道:
All the hpmcounters and the fixed counters (CY, IR, TM) can be represented
as a unified counter. Thus, the predicate function doesn't need handle each
case separately.

Simplify the predicate function so that we just handle things differently
between RV32/RV64 and S/HS mode.

Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
  target/riscv/csr.c | 112 +++++----------------------------------------
  1 file changed, 11 insertions(+), 101 deletions(-)

diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 1233bfa0a726..57dbbf9b09a0 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -74,6 +74,7 @@ static RISCVException ctr(CPURISCVState *env, int csrno)
      CPUState *cs = env_cpu(env);
      RISCVCPU *cpu = RISCV_CPU(cs);
      int ctr_index;
+    target_ulong ctr_mask;
      int base_csrno = CSR_CYCLE;
      bool rv32 = riscv_cpu_mxl(env) == MXL_RV32 ? true : false;
@@ -82,122 +83,31 @@ static RISCVException ctr(CPURISCVState *env, int csrno)
          base_csrno += 0x80;
      }
      ctr_index = csrno - base_csrno;
+    ctr_mask = BIT(ctr_index);
if ((csrno >= CSR_CYCLE && csrno <= CSR_INSTRET) ||
          (csrno >= CSR_CYCLEH && csrno <= CSR_INSTRETH)) {
          goto skip_ext_pmu_check;
      }
- if ((!cpu->cfg.pmu_num || !(cpu->pmu_avail_ctrs & BIT(ctr_index)))) {
+    if (!(cpu->pmu_avail_ctrs & ctr_mask)) {
          /* No counter is enabled in PMU or the counter is out of range */
          return RISCV_EXCP_ILLEGAL_INST;
      }
skip_ext_pmu_check: - if (env->priv == PRV_S) {
-        switch (csrno) {
-        case CSR_CYCLE:
-            if (!get_field(env->mcounteren, COUNTEREN_CY)) {
-                return RISCV_EXCP_ILLEGAL_INST;
-            }
-            break;
-        case CSR_TIME:
-            if (!get_field(env->mcounteren, COUNTEREN_TM)) {
-                return RISCV_EXCP_ILLEGAL_INST;
-            }
-            break;
-        case CSR_INSTRET:
-            if (!get_field(env->mcounteren, COUNTEREN_IR)) {
-                return RISCV_EXCP_ILLEGAL_INST;
-            }
-            break;
-        case CSR_HPMCOUNTER3...CSR_HPMCOUNTER31:
-            if (!get_field(env->mcounteren, 1 << ctr_index)) {
-                return RISCV_EXCP_ILLEGAL_INST;
-            }
-            break;
-        }
-        if (rv32) {
-            switch (csrno) {
-            case CSR_CYCLEH:
-                if (!get_field(env->mcounteren, COUNTEREN_CY)) {
-                    return RISCV_EXCP_ILLEGAL_INST;
-                }
-                break;
-            case CSR_TIMEH:
-                if (!get_field(env->mcounteren, COUNTEREN_TM)) {
-                    return RISCV_EXCP_ILLEGAL_INST;
-                }
-                break;
-            case CSR_INSTRETH:
-                if (!get_field(env->mcounteren, COUNTEREN_IR)) {
-                    return RISCV_EXCP_ILLEGAL_INST;
-                }
-                break;
-            case CSR_HPMCOUNTER3H...CSR_HPMCOUNTER31H:
-                if (!get_field(env->mcounteren, 1 << ctr_index)) {
-                    return RISCV_EXCP_ILLEGAL_INST;
-                }
-                break;
-            }
-        }
+    if (((env->priv == PRV_S) && (!get_field(env->mcounteren, ctr_mask))) ||
+       ((env->priv == PRV_U) && (!get_field(env->scounteren, ctr_mask)))) {
+        return RISCV_EXCP_ILLEGAL_INST;
      }
if (riscv_cpu_virt_enabled(env)) {
-        switch (csrno) {
-        case CSR_CYCLE:
-            if (!get_field(env->hcounteren, COUNTEREN_CY) &&
-                get_field(env->mcounteren, COUNTEREN_CY)) {
-                return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-            }
-            break;
-        case CSR_TIME:
-            if (!get_field(env->hcounteren, COUNTEREN_TM) &&
-                get_field(env->mcounteren, COUNTEREN_TM)) {
-                return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-            }
-            break;
-        case CSR_INSTRET:
-            if (!get_field(env->hcounteren, COUNTEREN_IR) &&
-                get_field(env->mcounteren, COUNTEREN_IR)) {
-                return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-            }
-            break;
-        case CSR_HPMCOUNTER3...CSR_HPMCOUNTER31:
-            if (!get_field(env->hcounteren, 1 << ctr_index) &&
-                 get_field(env->mcounteren, 1 << ctr_index)) {
-                return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-            }
-            break;
-        }
-        if (rv32) {
-            switch (csrno) {
-            case CSR_CYCLEH:
-                if (!get_field(env->hcounteren, COUNTEREN_CY) &&
-                    get_field(env->mcounteren, COUNTEREN_CY)) {
-                    return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-                }
-                break;
-            case CSR_TIMEH:
-                if (!get_field(env->hcounteren, COUNTEREN_TM) &&
-                    get_field(env->mcounteren, COUNTEREN_TM)) {
-                    return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-                }
-                break;
-            case CSR_INSTRETH:
-                if (!get_field(env->hcounteren, COUNTEREN_IR) &&
-                    get_field(env->mcounteren, COUNTEREN_IR)) {
-                    return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-                }
-                break;
-            case CSR_HPMCOUNTER3H...CSR_HPMCOUNTER31H:
-                if (!get_field(env->hcounteren, 1 << ctr_index) &&
-                     get_field(env->mcounteren, 1 << ctr_index)) {
-                    return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
-                }
-                break;
-            }
+        if (!get_field(env->mcounteren, ctr_mask)) {
+            /* The bit must be set in mcountern for HS mode access */
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
+        } else if (!get_field(env->hcounteren, ctr_mask)) {
+            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
          }

The logic is changed here. In original logic, RISCV_EXCP_VIRT_INSTRUCTION_FAULT is triggered when

!get_field(env->hcounteren, 1 << ctr_index) && get_field(env->mcounteren, 1 << 
ctr_index)

The new logic is RISCV_EXCP_VIRT_INSTRUCTION_FAULT is triggered when 
!get_field(env->mcounteren, ctr_mask)

or !get_field(env->hcounteren, 1 << ctr_index) && get_field(env->mcounteren, 1 
<< ctr_index)

Regards,

Weiwei Li

      }
  #endif




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