Patch "xtensa: fix cache aliasing handling code for WT cache" has been added to the 4.12-stable tree

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

xtensa: fix cache aliasing handling code for WT cache

to the 4.12-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-fix-cache-aliasing-handling-code-for-wt-cache.patch
and it can be found in the queue-4.12 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: Fri, 28 Jul 2017 17:42:59 -0700
Subject: xtensa: fix cache aliasing handling code for WT cache

From: Max Filippov <[email protected]>

commit 6d0f581d1768d3eaba15776e7dd1fdfec10cfe36 upstream.

Currently building kernel for xtensa core with aliasing WT cache fails with the following messages:

mm/memory.c:2152: undefined reference to flush_dcache_page' mm/memory.c:2332: undefined reference to local_flush_cache_page' mm/memory.c:1919: undefined reference to local_flush_cache_range' mm/memory.c:4179: undefined reference to copy_to_user_page' mm/memory.c:4183: undefined reference to `copy_from_user_page'

This happens because implementation of these functions is only compiled when data cache is WB, which looks wrong: even when data cache doesn't need flushing it still needs invalidation. The functions like __flush_[invalidate_]dcache_* are correctly defined for both WB and WT caches (and even if they weren't that'd still be ok, just slower).

Fix this by providing the same implementation of the above functions for both WB and WT cache.

---
 arch/xtensa/mm/cache.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

@@ -120,10 +120,6 @@ void copy_user_highpage(struct page *dst
 	preempt_enable();
 }
 
-#endif /* DCACHE_WAY_SIZE > PAGE_SIZE */
-
-#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
-
 /*
  * Any time the kernel writes to a user page cache page, or it is about to
  * read from a page cache page this routine is called.

@@ -208,7 +204,7 @@ void local_flush_cache_page(struct vm_ar
 	__invalidate_icache_page_alias(virt, phys);
 }
 
-#endif
+#endif /* DCACHE_WAY_SIZE > PAGE_SIZE */
 
 void
 update_mmu_cache(struct vm_area_struct * vma, unsigned long addr, pte_t *ptep)

@@ -225,7 +221,7 @@ update_mmu_cache(struct vm_area_struct *
 
 	flush_tlb_page(vma, addr);
 
-#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
+#if (DCACHE_WAY_SIZE > PAGE_SIZE)
 
 	if (!PageReserved(page) && test_bit(PG_arch_1, &page->flags)) {
 		unsigned long phys = page_to_phys(page);

@@ -256,7 +252,7 @@ update_mmu_cache(struct vm_area_struct *
  * flush_dcache_page() on the page.
  */
 
-#if (DCACHE_WAY_SIZE > PAGE_SIZE) && XCHAL_DCACHE_IS_WRITEBACK
+#if (DCACHE_WAY_SIZE > PAGE_SIZE)
 
 void copy_to_user_page(struct vm_area_struct *vma, struct page *page,
 		unsigned long vaddr, void *dst, const void *src,

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

queue-4.12/xtensa-don-t-limit-csum_partial-export-by-config_net.patch queue-4.12/xtensa-fix-cache-aliasing-handling-code-for-wt-cache.patch queue-4.12/xtensa-mm-cache-add-missing-export_symbols.patch