Add a helper to invoke the mremap() system call directly using
syscall(). This is useful as otherwise glibc and friends will filter out
newer flags like MREMAP_RELOCATE_ANON and MREMAP_MUST_RELOCATE_ANON thus
making it impossible to test this functionality.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
---
 tools/testing/selftests/mm/vm_util.c | 8 ++++++++
 tools/testing/selftests/mm/vm_util.h | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index 1357e2d6a7b6..a2f07b10c0e7 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -486,3 +486,11 @@ int close_procmap(struct procmap_fd *procmap)
 {
 	return close(procmap->fd);
 }
+
+void *sys_mremap(void *old_address, unsigned long old_size,
+		 unsigned long new_size, int flags, void *new_address)
+{
+	return (void *)syscall(__NR_mremap, (unsigned long)old_address,
+			       old_size, new_size, flags,
+			       (unsigned long)new_address);
+}
diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
index 9211ba640d9c..434a96b33738 100644
--- a/tools/testing/selftests/mm/vm_util.h
+++ b/tools/testing/selftests/mm/vm_util.h
@@ -95,6 +95,9 @@ static inline int open_self_procmap(struct procmap_fd *procmap_out)
 	return open_procmap(pid, procmap_out);
 }
 
+void *sys_mremap(void *old_address, unsigned long old_size,
+		 unsigned long new_size, int flags, void *new_address);
+
 /*
  * On ppc64 this will only work with radix 2M hugepage size
  */
-- 
2.49.0