introduce a new allocator that allocates 4k hardware-pages to back
64k linux-page. This allocator is only applicable on powerpc.

Signed-off-by: Ram Pai <linux...@us.ibm.com>
---
 tools/testing/selftests/vm/protection_keys.c |   29 ++++++++++++++++++++++++++
 1 files changed, 29 insertions(+), 0 deletions(-)

diff --git a/tools/testing/selftests/vm/protection_keys.c 
b/tools/testing/selftests/vm/protection_keys.c
index d9474f9..bffa890 100644
--- a/tools/testing/selftests/vm/protection_keys.c
+++ b/tools/testing/selftests/vm/protection_keys.c
@@ -758,6 +758,34 @@ void free_pkey_malloc(void *ptr)
        return ptr;
 }
 
+void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
+{
+       void *ptr;
+       int ret;
+
+#ifndef __powerpc64__
+       return PTR_ERR_ENOTSUP;
+#endif /*  __powerpc64__ */
+       dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+                       size, prot, pkey);
+       pkey_assert(pkey < NR_PKEYS);
+       ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+       pkey_assert(ptr != (void *)-1);
+
+       ret = syscall(__NR_subpage_prot, ptr, size, NULL);
+       if (ret) {
+               perror("subpage_perm");
+               return PTR_ERR_ENOTSUP;
+       }
+
+       ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
+       pkey_assert(!ret);
+       record_pkey_malloc(ptr, size);
+
+       dprintf1("%s() for pkey %d @ %p\n", __func__, pkey, ptr);
+       return ptr;
+}
+
 void *malloc_pkey_anon_huge(long size, int prot, u16 pkey)
 {
        int ret;
@@ -880,6 +908,7 @@ void setup_hugetlbfs(void)
 void *(*pkey_malloc[])(long size, int prot, u16 pkey) = {
 
        malloc_pkey_with_mprotect,
+       malloc_pkey_with_mprotect_subpage,
        malloc_pkey_anon_huge,
        malloc_pkey_hugetlb
 /* can not do direct with the pkey_mprotect() API:
-- 
1.7.1

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