Re: [PATCH v2] target/riscv: Fix incorrect PTE merge in walk_pte

[Bin Meng]

On Fri, Apr 22, 2022 at 10:53 AM Bin Meng <bmeng.cn@gmail.com> wrote:
>
> On Tue, Apr 5, 2022 at 1:34 AM Ralf Ramsauer
> <ralf.ramsauer@oth-regensburg.de> wrote:
> >
> > Two non-subsequent PTEs can be mapped to subsequent paddrs. In this
> > case, walk_pte will erroneously merge them.
> >
> > Enforce the split up, by tracking the virtual base address.
> >
> > Let's say we have the mapping:
> > 0x81200000 -> 0x89623000 (4K)
> > 0x8120f000 -> 0x89624000 (4K)
> >
> > Before, walk_pte would have shown:
> >
> > vaddr            paddr            size             attr
> > ---------------- ---------------- ---------------- -------
> > 0000000081200000 0000000089623000 0000000000002000 rwxu-ad
> >
> > as it only checks for subsequent paddrs. With this patch, it becomes:
> >
> > vaddr            paddr            size             attr
> > ---------------- ---------------- ---------------- -------
> > 0000000081200000 0000000089623000 0000000000001000 rwxu-ad
> > 000000008120f000 0000000089624000 0000000000001000 rwxu-ad
> >
> > Signed-off-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
> > ---
> >  target/riscv/monitor.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/target/riscv/monitor.c b/target/riscv/monitor.c
> > index 7efb4b62c1..9dc4cb1156 100644
> > --- a/target/riscv/monitor.c
> > +++ b/target/riscv/monitor.c
> > @@ -84,6 +84,7 @@ static void walk_pte(Monitor *mon, hwaddr base, 
> > target_ulong start,
> >  {
> >      hwaddr pte_addr;
> >      hwaddr paddr;
> > +    target_ulong last_start = -1;
> >      target_ulong pgsize;
> >      target_ulong pte;
> >      int ptshift;
> > @@ -116,7 +117,8 @@ static void walk_pte(Monitor *mon, hwaddr base, 
> > target_ulong start,
> >                   * contiguous mapped block details.
> >                   */
>
> Please also update the comments above to mention the new case you added here.
>

Otherwise,

Reviewed-by: Bin Meng <bmeng.cn@gmail.com>