Re: [PULL v3 36/42] target/riscv: Remove the hardcoded MSTATUS_SD macro

[LIU Zhiwei]

On 5/21/21 6:55 AM, Alistair Francis wrote:
> On Thu, May 20, 2021 at 11:55 PM Peter Maydell <peter.maydell@linaro.org> wrote:
> > On Tue, 11 May 2021 at 11:22, Alistair Francis <alistair.francis@wdc.com> wrote:
> > > Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
> > > Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> > > Message-id: 
> > > fcc125d96da941b56c817c9dd6068dc36478fc53.1619234854.git.alistair.francis@wdc.com
> > > ---
> > >   target/riscv/cpu_bits.h  | 10 ----------
> > >   target/riscv/csr.c       | 12 ++++++++++--
> > >   target/riscv/translate.c | 19 +++++++++++++++++--
> > >   3 files changed, 27 insertions(+), 14 deletions(-)
> > > diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> > > index 26eccc5eb1..a596f80f20 100644
> > > --- a/target/riscv/translate.c
> > > +++ b/target/riscv/translate.c
> > > @@ -78,6 +78,17 @@ static inline bool has_ext(DisasContext *ctx, uint32_t ext)
> > >       return ctx->misa & ext;
> > >   }
> > >
> > > +#ifdef TARGET_RISCV32
> > > +# define is_32bit(ctx)  true
> > > +#elif defined(CONFIG_USER_ONLY)
> > > +# define is_32bit(ctx)  false
> > > +#else
> > > +static inline bool is_32bit(DisasContext *ctx)
> > > +{
> > > +    return (ctx->misa & RV32) == RV32;
> > > +}
> > > +#endif
> > Hi; Coverity points out (CID 1453107) that this is_32bit() function
> > can never return true for at least some build configs, because RV32
> > is defined as ((target_ulong)1 << (TARGET_LONG_BITS - 2))
> > but ctx->misa is a uint32_t field, which (if TARGET_LONG_BITS is
> > 64) is not big enough for the RV32 bit.
> This seems like a false positive as RV32 is defined as:
>
> ((target_ulong)1 << (TARGET_LONG_BITS - 2))
>
> while ctx->misa is a target_ulong.

Although the misa in RISCVCPUState is target_ulong, the misa in 
DisasContext is uint32_t.

I think we should  fix up the misa in DisasContext.

Zhiwei

> So it should always be able to return true.
>
> Alistair
>
> > Bug, or false positive ?
> >
> > thanks
> > -- PMM