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

[Richard Henderson <richard.henderson@linaro.org>]

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~