rickl...@linux.vnet.ibm.com writes: > From: Rick Lindsley <rickl...@linux.vnet.ibm.com> > > With the 512TB virtual addressing capability, a new field was added to > the paca and mm_context (addr_limit) to track the process's desire to > use the larger addressing space. Functions in the radix-enabled path > (mmap.c) were modified to inspect this value when deciding whether to > grant or deny requests in that range. > > However, the non-radix path falls through to the old, hashed slice code > (slice_get_unmapped_area, etc.) and these code paths still inspect > task_size. The same attention to addr_limit made in (for example) > radix__arch_get_unmapped_area() should also be applied to (correspondingly) > slice_get_unmapped_area().
I would suggest we don't do this change now. But rather we audit the usage of TASK_SIZE(), mm->task_size and move them correctly to mm->task_size and mm->context.addr_limit. The context.addr_limit is added as an optimization for slice_mask copy and we need to closely audit to make sure we can use that as a boundary condition for error checking in case of mmap. IMHO we should do this while consoliding TASK_SIZE/mm->task_size/mm->context.addr_limit. A previous attempt can be found at https://lkml.kernel.org/r/20161230155634.8692-1-dsafo...@virtuozzo.com We should start working in that direction. Some arch even have thread_info.addr_limit > > Signed-off-by: Rick Lindsley <rickl...@linux.vnet.ibm.com> > --- > arch/powerpc/mm/slice.c | 12 ++++++------ > 1 files changed, 6 insertions(+), 6 deletions(-) > > diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c > index 251b6ba..c023bff 100644 > --- a/arch/powerpc/mm/slice.c > +++ b/arch/powerpc/mm/slice.c > @@ -96,7 +96,7 @@ static int slice_area_is_free(struct mm_struct *mm, > unsigned long addr, > { > struct vm_area_struct *vma; > > - if ((mm->task_size - len) < addr) > + if ((mm->addr_limit - len) < addr) > return 0; > vma = find_vma(mm, addr); > return (!vma || (addr + len) <= vma->vm_start); > @@ -133,7 +133,7 @@ static void slice_mask_for_free(struct mm_struct *mm, > struct slice_mask *ret) > if (!slice_low_has_vma(mm, i)) > ret->low_slices |= 1u << i; > > - if (mm->task_size <= SLICE_LOW_TOP) > + if (mm->addr_limit <= SLICE_LOW_TOP) > return; > > for (i = 0; i < GET_HIGH_SLICE_INDEX(mm->context.addr_limit); i++) > @@ -444,20 +444,20 @@ unsigned long slice_get_unmapped_area(unsigned long > addr, unsigned long len, > bitmap_zero(compat_mask.high_slices, SLICE_NUM_HIGH); > > /* Sanity checks */ > - BUG_ON(mm->task_size == 0); > + BUG_ON(mm->addr_limit == 0); > VM_BUG_ON(radix_enabled()); > > slice_dbg("slice_get_unmapped_area(mm=%p, psize=%d...\n", mm, psize); > slice_dbg(" addr=%lx, len=%lx, flags=%lx, topdown=%d\n", > addr, len, flags, topdown); > > - if (len > mm->task_size) > + if (len > mm->addr_limit) > return -ENOMEM; > if (len & ((1ul << pshift) - 1)) > return -EINVAL; > if (fixed && (addr & ((1ul << pshift) - 1))) > return -EINVAL; > - if (fixed && addr > (mm->task_size - len)) > + if (fixed && addr > (mm->addr_limit - len)) > return -ENOMEM; > > /* If hint, make sure it matches our alignment restrictions */ > @@ -465,7 +465,7 @@ unsigned long slice_get_unmapped_area(unsigned long addr, > unsigned long len, > addr = _ALIGN_UP(addr, 1ul << pshift); > slice_dbg(" aligned addr=%lx\n", addr); > /* Ignore hint if it's too large or overlaps a VMA */ > - if (addr > mm->task_size - len || > + if (addr > mm->addr_limit - len || > !slice_area_is_free(mm, addr, len)) > addr = 0; > } > -- > 1.7.1 -aneesh
