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Message-ID: <CAOnJCUL0_R18GY3b00tcW3Pez49McuYBL0+Lan2h-w7x1LuOYA@mail.gmail.com>
Date:   Thu, 26 May 2022 00:35:16 -0700
From:   Atish Patra <atishp@...shpatra.org>
To:     Frank Chang <frank.chang@...ive.com>
Cc:     Atish Patra <atishp@...osinc.com>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        Bin Meng <bmeng.cn@...il.com>,
        Alistair Francis <alistair.francis@....com>,
        Bin Meng <bin.meng@...driver.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        "qemu-devel@...gnu.org Developers" <qemu-devel@...gnu.org>,
        "open list:RISC-V" <qemu-riscv@...gnu.org>
Subject: Re: [PATCH v9 09/12] target/riscv: Simplify counter predicate function

On Wed, May 25, 2022 at 3:24 AM Frank Chang <frank.chang@...ive.com> wrote:
>
> On Tue, May 24, 2022 at 8:02 AM Atish Patra <atishp@...osinc.com> wrote:
>>
>> 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@...il.com>
>> Acked-by: Alistair Francis <alistair.francis@....com>
>> Signed-off-by: Atish Patra <atishp@...osinc.com>
>> ---
>>  target/riscv/csr.c | 111 ++++-----------------------------------------
>>  1 file changed, 10 insertions(+), 101 deletions(-)
>>
>> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
>> index 723b52d836d3..e229f53c674d 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 +83,30 @@ 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->cfg.pmu_num || !(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))) {
>
>
> Should we also check PRV_U against env->scounteren here?
>

Ahh yes. That's required while hpmcounter is being accessed from the
userspace. Good catch. Thanks. Will fix it.

> Regards,
> Frank Chang
>
>>
>> +        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;
>>          }
>>      }
>>  #endif
>> --
>> 2.25.1
>>
>>


-- 
Regards,
Atish

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