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Subject[RFC, PATCH 09/22] mm, rmap: Add arch-specific field into anon_vma
Date
MKTME enabling requires a way to find out which encryption KeyID has to
be used to access the page. There's not enough space in struct page to
store this information.

As a way out we can store it in anon_vma for the page: all pages in the
same anon_vma tree will be encrypted with the same KeyID.

This patch adds arch-specific field into anon_vma. For x86 it will be
used to store KeyID.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
include/linux/rmap.h | 6 ++++++
mm/rmap.c | 15 ++++++++++++---
2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 988d176472df..54c7ea330827 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -12,6 +12,10 @@
#include <linux/memcontrol.h>
#include <linux/highmem.h>

+#ifndef arch_anon_vma
+struct arch_anon_vma {};
+#endif
+
/*
* The anon_vma heads a list of private "related" vmas, to scan if
* an anonymous page pointing to this anon_vma needs to be unmapped:
@@ -59,6 +63,8 @@ struct anon_vma {

/* Interval tree of private "related" vmas */
struct rb_root_cached rb_root;
+
+ struct arch_anon_vma arch_anon_vma;
};

/*
diff --git a/mm/rmap.c b/mm/rmap.c
index 47db27f8049e..c0470a69a4c9 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -74,7 +74,14 @@
static struct kmem_cache *anon_vma_cachep;
static struct kmem_cache *anon_vma_chain_cachep;

-static inline struct anon_vma *anon_vma_alloc(void)
+#ifndef arch_anon_vma_init
+static inline void arch_anon_vma_init(struct anon_vma *anon_vma,
+ struct vm_area_struct *vma)
+{
+}
+#endif
+
+static inline struct anon_vma *anon_vma_alloc(struct vm_area_struct *vma)
{
struct anon_vma *anon_vma;

@@ -88,6 +95,8 @@ static inline struct anon_vma *anon_vma_alloc(void)
* from fork, the root will be reset to the parents anon_vma.
*/
anon_vma->root = anon_vma;
+
+ arch_anon_vma_init(anon_vma, vma);
}

return anon_vma;
@@ -186,7 +195,7 @@ int __anon_vma_prepare(struct vm_area_struct *vma)
anon_vma = find_mergeable_anon_vma(vma);
allocated = NULL;
if (!anon_vma) {
- anon_vma = anon_vma_alloc();
+ anon_vma = anon_vma_alloc(vma);
if (unlikely(!anon_vma))
goto out_enomem_free_avc;
allocated = anon_vma;
@@ -337,7 +346,7 @@ int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
return 0;

/* Then add our own anon_vma. */
- anon_vma = anon_vma_alloc();
+ anon_vma = anon_vma_alloc(vma);
if (!anon_vma)
goto out_error;
avc = anon_vma_chain_alloc(GFP_KERNEL);
--
2.16.1
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