MIPS: cache: Provide cache flush operations for XFS

Until now flush_kernel_vmap_range() and invalidate_kernel_vmap_range() did
not exist on MIPS resulting in heavy cache corruption on XFS filesystems.

Left for the post-3.0 time: optimization and make this work with highmem,
too.  Since the combination of highmem + cache aliases atm doesn't work
this isn't a regression.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/2505/

arch/mips/mm/cache.c

@@ -35,6 +35,11 @@ void (*local_flush_icache_range)(unsigned long start, unsigned long end);
 void (*__flush_cache_vmap)(void);
 void (*__flush_cache_vunmap)(void);
 
+void (*__flush_kernel_vmap_range)(unsigned long vaddr, int size);
+void (*__invalidate_kernel_vmap_range)(unsigned long vaddr, int size);
+
+EXPORT_SYMBOL_GPL(__flush_kernel_vmap_range);
+
 /* MIPS specific cache operations */
 void (*flush_cache_sigtramp)(unsigned long addr);
 void (*local_flush_data_cache_page)(void * addr);