Re: [PATCH v4 3/6] target/riscv: Add helper functions to calculate current number of masked bits for pointer masking

[Richard Henderson]

On 1/19/24 04:21, Deepak Gupta wrote:
> On Tue, Jan 9, 2024 at 2:31 AM Alexey Baturo <baturo.alexey@gmail.com> wrote:
> > From: Alexey Baturo <baturo.alexey@gmail.com>
> >
> > Signed-off-by: Alexey Baturo <baturo.alexey@gmail.com>
> > ---
>
> > +
> > +bool riscv_cpu_virt_mem_enabled(CPURISCVState *env)
> > +{
> > +    bool virt_mem_en = false;
> > +#ifndef CONFIG_USER_ONLY
> > +    int satp_mode = 0;
> > +    int priv_mode = cpu_address_mode(env);
> > +    /* Get current PMM field */
> > +    if (riscv_cpu_mxl(env) == MXL_RV32) {
> > +        satp_mode = get_field(env->satp, SATP32_MODE);
> > +    } else {
> > +        satp_mode = get_field(env->satp, SATP64_MODE);
> > +    }
> > +    virt_mem_en = ((satp_mode != VM_1_10_MBARE) && (priv_mode != PRV_M));
> > +#endif
> > +    return virt_mem_en;
>
> Obsessing a little bit on how to test PM enabled binaries with qemu-user.
> If we return false above then we're not allowed to test binaries with
> pointer masking enabled with qemu-user.
> That use case is not required?

In a previous round I suggested that the ifdefs are not necessary.
But for now it will always be off for qemu-user.

At some point pointer masking will be in hardware, and the kernel will gain support for 
it, and there will likely be a prctl() added for it.  At the point the kernel finalizes 
the API, you will be able to enable pointer masking for qemu-user.


r~