RE: [PATCHv2] ARM: ioremap: Fix static vm area boundary checking.

[Li.Xiubo@xxxxxxxxxxxxx]

> Subject: Re: [PATCHv2] ARM: ioremap: Fix static vm area boundary checking.
> 
> On Fri, May 16, 2014 at 1:28 AM, Nicolas Pitre <nicolas.pitre@xxxxxxxxxx>
> wrote:
> > On Thu, 15 May 2014, Richard Lee wrote:
> >
> >> Static vm area boundary check:
> >>
> >>       paddr1 --->|       |
> >>                  |       |
> >>                  |-------| <-\--- svm->vm->addr(is page aligned)
> >>       paddr2 --->|       |    |
> >>                  |     --| <--|-- svm->vm->phys_addr
> >>                  |       |    |
> >>       paddr3 --->|       |    |
> >>                  |       |    |
> >>                  |-------| <--|-- next page boundary
> >>                  |       |    |
> >>       paddr4 --->|       |    | <----- svm->vm->size(including guard page)
> >>                  |       |    |
> >>                  |       |    |
> >> max paddr_end -->|-------| <--|-- svm->vm's phys_addr_end
> >>                  | ///// |    |
> >>       paddr5 --->| guard |    |
> >>                  | page  |    |
> >>                  | ///// |    |
> >>                   -------  <-/--- svm->vm->addr + svm->vm_size
> >>
> >> <1> If the paddr == paddr1, then continue;
> >> <2> If the paddr == paddr2~paddr4 and paddr_end > phys_addr_end,
> >>     then continue;
> >> <3> if the paddr >= paddr5 then continue;
> >>
> >> Signed-off-by: Richard Lee <superlibj8301@xxxxxxxxx>
> >
> > instead of doing this repeatedly, why not simply ensure the recorded
> > static vm information is already page aligned in the first place?
> >
> 
> Sorry, I'm not very sure what vm information you meant here.
> 
> And the 'svm->vm->addr' and 'svm->vm->size' are all page aligned
> already, but we cannot make sure that the 'paddr' and
> 'svm->vm->phys_addr' are page aligned.
> 

The paddr and svm->vm->phys_addr are all already pfn aligned here.
What we should fix about is the boundary of them. 

Thanks,
BRs
Xiubo


> 
> Thanks,
> 
> BRs
> Richard Lee
> 
> >
> >
> >> ---
> >>
> >>
> >> Change in V2:
> >>  - PAGE_SIZE --> PAGE_MASK
> >>  - remove the 'size' page size align operation.
> >>
> >>
> >>
> >>
> >>
> >>
> >>  arch/arm/mm/ioremap.c | 40 ++++++++++++++++++++++++++++++++++++++--
> >>  1 file changed, 38 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
> >> index be69333..f235ab7 100644
> >> --- a/arch/arm/mm/ioremap.c
> >> +++ b/arch/arm/mm/ioremap.c
> >> @@ -47,16 +47,52 @@ static struct static_vm
> *find_static_vm_paddr(phys_addr_t paddr,
> >>  {
> >>       struct static_vm *svm;
> >>       struct vm_struct *vm;
> >> +     size_t offset;
> >> +
> >> +     offset = paddr & ~PAGE_MASK;
> >>
> >>       list_for_each_entry(svm, &static_vmlist, list) {
> >> +             phys_addr_t paddr_end, phys_addr_end;
> >> +             size_t vmoff;
> >> +
> >>               vm = &svm->vm;
> >>               if (!(vm->flags & VM_ARM_STATIC_MAPPING))
> >>                       continue;
> >>               if ((vm->flags & VM_ARM_MTYPE_MASK) != VM_ARM_MTYPE(mtype))
> >>                       continue;
> >>
> >> -             if (vm->phys_addr > paddr ||
> >> -                     paddr + size - 1 > vm->phys_addr + vm->size - 1)
> >> +             /* Static vm area boundary check:
> >> +              *
> >> +              *       paddr1 --->|       |
> >> +              *                  |       |
> >> +              *                  |-------| <-\--- svm->vm->addr(page
> aligned)
> >> +              *       paddr2 --->|       |    |
> >> +              *                  |     --| <--|-- svm->vm->phys_addr
> >> +              *                  |       |    |
> >> +              *       paddr3 --->|       |    |
> >> +              *                  |       |    |
> >> +              *                  |-------| <--|-- next page boundary
> >> +              *                  |       |    |
> >> +              *       paddr4 --->|       |    | <----- svm->vm->size,
> >> +              *                  |       |    |         including guard
> page
> >> +              *                  |       |    |
> >> +              * max paddr_end -->|-------| <--|-- svm->vm's phys_addr_end
> >> +              *                  | ///// |    |
> >> +              *       paddr5 --->| guard |    |
> >> +              *                  | page  |    |
> >> +              *                  | ///// |    |
> >> +              *                   -------  <-/-- svm->vm->addr + svm-
> >vm_size
> >> +              *
> >> +              * <1> If paddr == paddr1, then continue;
> >> +              * <2> If paddr == paddr2~paddr4 and paddr_end >
> phys_addr_end,
> >> +              *     then continue;
> >> +              * <3> if paddr >= paddr5 then continue;
> >> +              */
> >> +             vmoff = vm->phys_addr & ~PAGE_MASK;
> >> +             phys_addr_end = vm->phys_addr + vm->size - PAGE_SIZE - vmoff;
> >> +             paddr_end = paddr + size - offset;
> >> +             if (__phys_to_pfn(vm->phys_addr) > __phys_to_pfn(paddr) ||
> >> +                     paddr_end - 1 > phys_addr_end - 1)
> >>                       continue;
> >>
> >>               return svm;
> >> --
> >> 1.8.4
> >>
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