Commit-ID: d4925e00d59698a201231cf99dce47d8b922bb34
Gitweb: http://git.kernel.org/tip/d4925e00d59698a201231cf99dce47d8b922bb34
Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Fri, 12 Feb 2016 13:02:16 -0800
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
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 <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: Dominik Dingel <dingel@xxxxxxxxxxxxxxxxxx>
Cc: Eric B Munson <emunson@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Jason Low <jason.low2@xxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Sasha Levin <sasha.levin@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Link: http://lkml.kernel.org/r/20160212210216.C3824032@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
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);
--
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