[PATCH v2] riscv: don't allow write but not read page mapping request in mmap

[Celeste Liu]

On Mon, Jun 13, 2022 at 01:44:28PM +0800, Guo Ren wrote:
> Yes, PROT_EXEC would prevent next PROT_READ check.
> 
> Looks good to me.
> 
> Reviewed-by: Guo Ren <guoren at kernel.org>

> > -               if (unlikely(!(prot & PROT_READ)))
> > -                       return -EINVAL;
> Could we put your comment here?
> 
> /*
>  * As mentioned in Table 4.5 in RISC-V spec Volume 2 Section 4.3 version
>  * "20211203 Privileged Architecture v1.12, Ratified"[1], the PTE permission
>  * bit combination of "write+!read" is "Reserved for future use.". Hence, don't
>  * allow such mapping request in mmap call. In the current code[2], write+exec
>  * only is marked as invalid, but write only is not marked as invalid.
>  */
> 

ok, I will add it in next verison.

--
Best Regards
 Coelacanthus
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