[PATCH 13/25] mm: factor out VMA fault permission checking
From: Dave Hansen <hidden>
Date: 2015-09-28 19:22:29
Also in:
lkml
From: Dave Hansen <dave.hansen@linux.intel.com> This code matches a fault condition up with the VMA and ensures that the VMA allows the fault to be handled instead of just erroring out. We will be extending this in a moment to comprehend protection keys. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> --- b/mm/gup.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff -puN mm/gup.c~pkeys-10-pte-fault mm/gup.c
--- a/mm/gup.c~pkeys-10-pte-fault 2015-09-28 11:39:46.790221164 -0700
+++ b/mm/gup.c 2015-09-28 11:39:46.794221345 -0700@@ -554,6 +554,17 @@ next_page: } EXPORT_SYMBOL(__get_user_pages); +bool vma_permits_fault(struct vm_area_struct *vma, unsigned int fault_flags) +{ + vm_flags_t vm_flags = + (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ; + + if (!(vm_flags & vma->vm_flags)) + return false; + + return true; +} + /* * fixup_user_fault() - manually resolve a user page fault * @tsk: the task_struct to use for page fault accounting, or
@@ -585,15 +596,13 @@ int fixup_user_fault(struct task_struct unsigned long address, unsigned int fault_flags) { struct vm_area_struct *vma; - vm_flags_t vm_flags; int ret; vma = find_extend_vma(mm, address); if (!vma || address < vma->vm_start) return -EFAULT; - vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ; - if (!(vm_flags & vma->vm_flags)) + if (!vma_permits_fault(vma, fault_flags)) return -EFAULT; ret = handle_mm_fault(mm, vma, address, fault_flags);
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