Commit-ID: d4925e00d59698a201231cf99dce47d8b922bb34 Gitweb: http://git.kernel.org/tip/d4925e00d59698a201231cf99dce47d8b922bb34 Author: Dave Hansen <[email protected]> AuthorDate: Fri, 12 Feb 2016 13:02:16 -0800 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 18 Feb 2016 09:32:43 +0100
mm/gup: Factor out VMA fault permission checking 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 <[email protected]> Reviewed-by: Thomas Gleixner <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Aneesh Kumar K.V <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Brian Gerst <[email protected]> Cc: Dan Williams <[email protected]> Cc: Dave Hansen <[email protected]> Cc: Denys Vlasenko <[email protected]> Cc: Dominik Dingel <[email protected]> Cc: Eric B Munson <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Jason Low <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Sasha Levin <[email protected]> Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- mm/gup.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index de24ef4..b935c2c 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -610,6 +610,18 @@ 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 @@ -645,7 +657,6 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm, bool *unlocked) { struct vm_area_struct *vma; - vm_flags_t vm_flags; int ret, major = 0; if (unlocked) @@ -656,8 +667,7 @@ 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);
