Re: [PATCH v3 2/3] target/riscv/pmp.c: Fix the index offset on RV64

[Bin Meng]

Hi Zong,

On Tue, Jul 21, 2020 at 8:41 PM Zong Li <zong.li@sifive.com> wrote:
>
> On RV64, the reg_index is 2 (pmpcfg2 CSR) after the seventh pmp
> entry, it is not 1 (pmpcfg1 CSR) like RV32. In the original
> implementation, the second parameter of pmp_write_cfg is
> "reg_index * sizeof(target_ulong)", and we get the the result
> which is started from 16 if reg_index is 2, but we expect that
> it should be started from 8. Separate the implementation for
> RV32 and RV64 respectively.
>
> Signed-off-by: Zong Li <zong.li@sifive.com>
>
> Changed in v3:
>  - Refine the implementation. Suggested by Bin Meng.
>
> Changed in v2:
>  - Move out the shifting operation from loop. Suggested by Bin Meng.

As I mentioned previously, these changelog should go after --- below.
It should not appear in the commit message.

> ---
>  target/riscv/pmp.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
> index 2a2b9f5363..f2d50bace5 100644
> --- a/target/riscv/pmp.c
> +++ b/target/riscv/pmp.c
> @@ -318,6 +318,10 @@ void pmpcfg_csr_write(CPURISCVState *env, uint32_t 
> reg_index,
>          return;
>      }
>
> +#if defined(TARGET_RISCV64)
> +    reg_index >>= 1;
> +#endif
> +
>      for (i = 0; i < sizeof(target_ulong); i++) {
>          cfg_val = (val >> 8 * i)  & 0xff;
>          pmp_write_cfg(env, (reg_index * sizeof(target_ulong)) + i,
> @@ -335,6 +339,10 @@ target_ulong pmpcfg_csr_read(CPURISCVState *env, 
> uint32_t reg_index)
>      target_ulong cfg_val = 0;
>      target_ulong val = 0;
>
> +#if defined(TARGET_RISCV64)
> +    reg_index >>= 1;
> +#endif

We should also move the following:

    trace_pmpcfg_csr_read(env->mhartid, reg_index, cfg_val);

before shifting reg_index. Otherwise it traces the wrong pmpcfg CSR read.

> +
>      for (i = 0; i < sizeof(target_ulong); i++) {
>          val = pmp_read_cfg(env, (reg_index * sizeof(target_ulong)) + i);
>          cfg_val |= (val << (i * 8));
> --

Regards,
Bin