| Message ID | 1400232920-25079-1-git-send-email-Li.Xiubo@freescale.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, 16 May 2014, Xiubo Li wrote: > For each vmalloc area, there is one guard page at the end of it. > so the vm->size = PAGE_ALIGN(offset + request size) + guard page size. Nope. There is no guard page for statically created vmalloc areas. > Signed-off-by: Richard Lee <superlibj8301@gmail.com> > Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com> > Cc: Nicolas Pitre <nico@linaro.org> > Cc: Santosh Shilimkar <santosh.shilimkar@ti.com> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > --- > arch/arm/mm/ioremap.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c > index be69333..758e8f7 100644 > --- a/arch/arm/mm/ioremap.c > +++ b/arch/arm/mm/ioremap.c > @@ -49,14 +49,18 @@ static struct static_vm *find_static_vm_paddr(phys_addr_t paddr, > struct vm_struct *vm; > > list_for_each_entry(svm, &static_vmlist, list) { > + phys_addr_t paddr_end, phys_addr_end; > + > 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) > + /* The PAGE_SIZE here is vmalloc area's guard page */ > + phys_addr_end = vm->phys_addr + vm->size - PAGE_SIZE - 1; > + paddr_end = paddr + size - 1; > + if (vm->phys_addr > paddr || paddr_end > phys_addr_end) > continue; > > return svm; > -- > 1.8.4 >
> > For each vmalloc area, there is one guard page at the end of it. > > so the vm->size = PAGE_ALIGN(offset + request size) + guard page size. > > Nope. There is no guard page for statically created vmalloc areas. > Yes, you are right, I'm thinking why the static area has no guard page? Thanks very much, BRs Xiubo > > > Signed-off-by: Richard Lee <superlibj8301@gmail.com> > > Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com> > > Cc: Nicolas Pitre <nico@linaro.org> > > Cc: Santosh Shilimkar <santosh.shilimkar@ti.com> > > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> > > --- > > arch/arm/mm/ioremap.c | 8 ++++++-- > > 1 file changed, 6 insertions(+), 2 deletions(-) > > > > diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c > > index be69333..758e8f7 100644 > > --- a/arch/arm/mm/ioremap.c > > +++ b/arch/arm/mm/ioremap.c > > @@ -49,14 +49,18 @@ static struct static_vm > *find_static_vm_paddr(phys_addr_t paddr, > > struct vm_struct *vm; > > > > list_for_each_entry(svm, &static_vmlist, list) { > > + phys_addr_t paddr_end, phys_addr_end; > > + > > 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) > > + /* The PAGE_SIZE here is vmalloc area's guard page */ > > + phys_addr_end = vm->phys_addr + vm->size - PAGE_SIZE - 1; > > + paddr_end = paddr + size - 1; > > + if (vm->phys_addr > paddr || paddr_end > phys_addr_end) > > continue; > > > > return svm; > > -- > > 1.8.4 > >
On Mon, 19 May 2014, Li.Xiubo@freescale.com wrote: > > > For each vmalloc area, there is one guard page at the end of it. > > > so the vm->size = PAGE_ALIGN(offset + request size) + guard page size. > > > > Nope. There is no guard page for statically created vmalloc areas. > > > > Yes, you are right, I'm thinking why the static area has no guard page? The virtual addresses being used are provided by the static mapping descriptions themselves. Sometimes those mappings are large and contiguous, covering multiple peripherals at once with a single TLB, etc. There is simply no room for a guard page, or no guard page at all between different areas covered by a single section mapping (1MB worth of mapping from a single page table entry). All this to say that trying to enforce a guard page in those cases is likely to throw away all the performance advantage and conplexify things. Nicolas
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c index be69333..758e8f7 100644 --- a/arch/arm/mm/ioremap.c +++ b/arch/arm/mm/ioremap.c @@ -49,14 +49,18 @@ static struct static_vm *find_static_vm_paddr(phys_addr_t paddr, struct vm_struct *vm; list_for_each_entry(svm, &static_vmlist, list) { + phys_addr_t paddr_end, phys_addr_end; + 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) + /* The PAGE_SIZE here is vmalloc area's guard page */ + phys_addr_end = vm->phys_addr + vm->size - PAGE_SIZE - 1; + paddr_end = paddr + size - 1; + if (vm->phys_addr > paddr || paddr_end > phys_addr_end) continue; return svm;