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

From: Richard Lee
Date: Thu May 15 2014 - 21:45:52 EST


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.


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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