parisc: Optimize flush_kernel_vmap_range and invalidate_kernel_vmap_range

The previously submitted patch did not resolve the random segmentation
faults observed on the phantom buildd system.  There are still
unresolved problems with the Debian 4.8 and 4.9 kernels on C8000.

The attached patch removes the flush of the offset map pages and does a
whole data cache flush for large ranges.  No other arch flushes the
offset map in these routines as far as I can tell.

I have not observed any random segmentation faults on rp3440 in two
weeks of testing with 4.10.0 and 4.10.1.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Cc: stable@vger.kernel.org      # v4.8+
Signed-off-by: Helge Deller <deller@gmx.de>

diff --git a/arch/parisc/include/asm/cacheflush.h b/arch/parisc/include/asm/cacheflush.h
index 19c9c3c5f267eac813edf6c5fc6f358301d2a639..c7e15cc5c6683b423d028b1557fc0dc9b7dd5a16 100644 (file)
--- a/arch/parisc/include/asm/cacheflush.h
+++ b/arch/parisc/include/asm/cacheflush.h
@@ -43,28 +43,9 @@ static inline void flush_kernel_dcache_page(struct page *page)
 
 #define flush_kernel_dcache_range(start,size) \
        flush_kernel_dcache_range_asm((start), (start)+(size));
-/* vmap range flushes and invalidates.  Architecturally, we don't need
- * the invalidate, because the CPU should refuse to speculate once an
- * area has been flushed, so invalidate is left empty */
-static inline void flush_kernel_vmap_range(void *vaddr, int size)
-{
-       unsigned long start = (unsigned long)vaddr;
-
-       flush_kernel_dcache_range_asm(start, start + size);
-}
-static inline void invalidate_kernel_vmap_range(void *vaddr, int size)
-{
-       unsigned long start = (unsigned long)vaddr;
-       void *cursor = vaddr;
 
-       for ( ; cursor < vaddr + size; cursor += PAGE_SIZE) {
-               struct page *page = vmalloc_to_page(cursor);
-
-               if (test_and_clear_bit(PG_dcache_dirty, &page->flags))
-                       flush_kernel_dcache_page(page);
-       }
-       flush_kernel_dcache_range_asm(start, start + size);
-}
+void flush_kernel_vmap_range(void *vaddr, int size);
+void invalidate_kernel_vmap_range(void *vaddr, int size);
 
 #define flush_cache_vmap(start, end)           flush_cache_all()
 #define flush_cache_vunmap(start, end)         flush_cache_all()

diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c
index 0dc72d5de861539e5c16ff2ecd49f205e37775e6..c32a0909521665b5f08c22ef37fa8d8f9c654012 100644 (file)
--- a/arch/parisc/kernel/cache.c
+++ b/arch/parisc/kernel/cache.c
@@ -616,3 +616,25 @@ flush_cache_page(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long
                __flush_cache_page(vma, vmaddr, PFN_PHYS(pfn));
        }
 }
+
+void flush_kernel_vmap_range(void *vaddr, int size)
+{
+       unsigned long start = (unsigned long)vaddr;
+
+       if ((unsigned long)size > parisc_cache_flush_threshold)
+               flush_data_cache();
+       else
+               flush_kernel_dcache_range_asm(start, start + size);
+}
+EXPORT_SYMBOL(flush_kernel_vmap_range);
+
+void invalidate_kernel_vmap_range(void *vaddr, int size)
+{
+       unsigned long start = (unsigned long)vaddr;
+
+       if ((unsigned long)size > parisc_cache_flush_threshold)
+               flush_data_cache();
+       else
+               flush_kernel_dcache_range_asm(start, start + size);
+}
+EXPORT_SYMBOL(invalidate_kernel_vmap_range);