Messages in this thread Patch in this message | | | Subject | [PATCH 15/31] mm: factor out VMA fault permission checking | From | Dave Hansen <> | Date | Fri, 29 Jan 2016 10:17:03 -0800 |
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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> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> ---
b/mm/gup.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-)
diff -puN mm/gup.c~pkeys-10-pte-fault mm/gup.c --- a/mm/gup.c~pkeys-10-pte-fault 2016-01-28 15:52:22.856518359 -0800 +++ b/mm/gup.c 2016-01-28 15:52:22.860518543 -0800 @@ -611,6 +611,18 @@ 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; + + 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 @@ -646,7 +658,6 @@ int fixup_user_fault(struct task_struct bool *unlocked) { struct vm_area_struct *vma; - vm_flags_t vm_flags; int ret, major = 0; if (unlocked) @@ -657,8 +668,7 @@ retry: 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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