On 24/06/2020 19:45, Andrew Morton wrote:
On Wed, 24 Jun 2020 18:52:40 +0100 Catalin Marinas <catalin.marinas@xxxxxxx> wrote:
From: Steven Price <steven.price@xxxxxxx>
Arm's Memory Tagging Extension (MTE) adds some metadata (tags) to
every physical page, when swapping pages out to disk it is necessary to
save these tags, and later restore them when reading the pages back.
Add some hooks along with dummy implementations to enable the
arch code to handle this.
Three new hooks are added to the swap code:
* arch_prepare_to_swap() and
* arch_swap_invalidate_page() / arch_swap_invalidate_area().
One new hook is added to shmem:
* arch_swap_restore_tags()
...
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -631,6 +631,29 @@ static inline int arch_unmap_one(struct mm_struct *mm,
}
#endif
+#ifndef __HAVE_ARCH_PREPARE_TO_SWAP
+static inline int arch_prepare_to_swap(struct page *page)
+{
+ return 0;
+}
+#endif
+
+#ifndef __HAVE_ARCH_SWAP_INVALIDATE
+static inline void arch_swap_invalidate_page(int type, pgoff_t offset)
+{
+}
+
+static inline void arch_swap_invalidate_area(int type)
+{
+}
+#endif
+
+#ifndef __HAVE_ARCH_SWAP_RESTORE_TAGS
+static inline void arch_swap_restore_tags(swp_entry_t entry, struct page *page)
+{
+}
+#endif
Presumably these three __HAVE_ARCH_ macros are to be defined in asm/pgtable.h?
That would be the idea (see patch 22). However:
Catalin - you've renamed __HAVE_ARCH_SWAP_RESTORE_TAGS in patch 22, but
not here!
Steve
