[PATCH] lib: sbi: Add additional range checks for RV32

[Andrew Jones <ajones@ventanamicro.com>]

On Sat, Aug 24, 2024 at 02:38:31PM GMT, Anup Patel wrote:
> On Wed, Aug 14, 2024 at 6:02?PM Andrew Jones <ajones@ventanamicro.com> wrote:
> >
> > On RV32, M-mode can only access the first 4G of the physical
> > address space because M-mode does not have an MMU to access the
> > full 34-bit physical address space. While we already ensure
> > the "hi" registers of RV32 physical address inputs are zero we
> > need to also ensure that the low register plus the size does
> > not cross into 4G address space. The check added to
> > sbi_domain_check_addr_range() should be enough for both DBCN
> > and SSE, but DBCN returns a different error code for high
> > addresses, so we patch that check too.
> >
> > Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> >
> > ---
> >
> > Should the SSE functions return SBI_ERR_FAILED in this case like DBCN
> > does? We'd need to patch the SSE spec to call out SBI_ERR_FAILED as
> > "Failed to write due to I/O errors." like DBCN does too.
> 
> Instead of special-casing wrap-around check separately for each SBI
> extension, I suggest:
> 1) Add one more requirement in section 3.2 of the SBI spec to prevent
> wrap-around
> 2) Update sbi_domain_check_addr_range() like this patch does.

Sounds good to me.

Thanks,
drew