Patch "xtensa: make __pa work with uncached KSEG addresses" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

xtensa: make __pa work with uncached KSEG addresses

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
xtensa-make-__pa-work-with-uncached-kseg-addresses.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Max Filippov <[email protected]>
Date: Wed, 29 Mar 2017 15:44:47 -0700
Subject: xtensa: make __pa work with uncached KSEG addresses

From: Max Filippov <[email protected]>

commit 2b83878dd74a7c73bedcb6600663c1c46836e8af upstream.

When __pa is applied to virtual address in uncached KSEG region the result is incorrect. Fix it by checking if the original address is in the uncached KSEG and adjusting the result. It looks better than masking off bits because pfn_valid would correctly work with new __pa results and it may be made working in noMMU case, once we get definition for uncached memory view.

This is required for the dma_common_mmap and DMA debug code to work
correctly: they both indirectly use __pa with coherent DMA addresses. In case of DMA debug the visible effect is false reports that an address mapped for DMA is accessed by CPU.

---
 arch/xtensa/include/asm/page.h |   13 +++++++++++++
 1 file changed, 13 insertions(+)

@@ -164,8 +164,21 @@ void copy_user_highpage(struct page *to,
 
 #define ARCH_PFN_OFFSET		(PHYS_OFFSET >> PAGE_SHIFT)
 
+#ifdef CONFIG_MMU
+static inline unsigned long ___pa(unsigned long va)
+{
+	unsigned long off = va - PAGE_OFFSET;
+
+	if (off >= XCHAL_KSEG_SIZE)
+		off -= XCHAL_KSEG_SIZE;
+
+	return off + PHYS_OFFSET;
+}
+#define __pa(x)	___pa((unsigned long)(x))
+#else
 #define __pa(x)	\
 	((unsigned long) (x) - PAGE_OFFSET + PHYS_OFFSET)
+#endif
 #define __va(x)	\
 	((void *)((unsigned long) (x) - PHYS_OFFSET + PAGE_OFFSET))
 #define pfn_valid(pfn) \

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/xtensa-make-__pa-work-with-uncached-kseg-addresses.patch