DEBUG_VIRTUAL, ensures that when __pa() is only called on
addresses for which its results are correct. For everything
else, we BUG_ON().
This changes the /dev/kmem ordering so that we check pfn_valid()
_before_ we call __pa(). This ensures we're not calling __pa()
with gibberish and avoids the BUG_ON() in those cases, instead
returning the error to userspace _before_ the __pa() call.
Signed-off-by: Dave Hansen <dave.han...@linux.intel.com>
---
linux.git-davehans/drivers/char/mem.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff -puN drivers/char/mem.c~make-devmem-work-on-highmem3a drivers/char/mem.c
--- linux.git/drivers/char/mem.c~make-devmem-work-on-highmem3a 2013-04-10
16:23:45.361087291 -0700
+++ linux.git-davehans/drivers/char/mem.c 2013-04-10 16:23:45.365087295
-0700
@@ -347,9 +347,6 @@ static int mmap_kmem(struct file *file,
*/
if (kernel_vaddr >= high_memory)
return -EIO;
- /* Turn a kernel-virtual address into a physical page frame */
- pfn = __pa(kernel_vaddr) >> PAGE_SHIFT;
-
/*
* RED-PEN: on some architectures there is more mapped memory than
* available in mem_map which pfn_valid checks for. Perhaps should add a
@@ -360,6 +357,9 @@ static int mmap_kmem(struct file *file,
if (!pfn_valid(pfn))
return -EIO;
+ /* Turn a kernel-virtual address into a physical page frame */
+ pfn = __pa(kernel_vaddr) >> PAGE_SHIFT;
+
vma->vm_pgoff = pfn;
return mmap_mem(file, vma);
}
_
--
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