[PATCH v1] selftests/mm: static process_madvise() wrapper for guard-pages

[Ryan Roberts <ryan.roberts@arm.com>]

The recently introduced guard-pages mm selftest uses the
process_madvise() syscall, a wrapper for which was added to glibc v2.36.
For those of us stuck with older distributions this causes a compile
error when compiling the mm selftests. For example Ubuntu 22.04 uses
glibc 2.35, which does not have the wrapper.

To workaround the issue, let's introduce our own static
process_madvise() wrapper that uses glibc's syscall() helper.

While we are at it, add the guard-page test suite to run_vmtests.sh so
that it can be automatically run by CI systems.

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---

Applies on top of mm-unstable (f349e79bfbf3)

Thanks,
Ryan

 tools/testing/selftests/mm/guard-pages.c  | 10 ++++++++--
 tools/testing/selftests/mm/run_vmtests.sh |  5 +++++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/mm/guard-pages.c b/tools/testing/selftests/mm/guard-pages.c
index d8f8dee9ebbd..ece37212a8a2 100644
--- a/tools/testing/selftests/mm/guard-pages.c
+++ b/tools/testing/selftests/mm/guard-pages.c
@@ -55,6 +55,12 @@ static int pidfd_open(pid_t pid, unsigned int flags)
 	return syscall(SYS_pidfd_open, pid, flags);
 }

+static ssize_t sys_process_madvise(int pidfd, const struct iovec *iovec,
+				   size_t n, int advice, unsigned int flags)
+{
+	return syscall(__NR_process_madvise, pidfd, iovec, n, advice, flags);
+}
+
 /*
  * Enable our signal catcher and try to read/write the specified buffer. The
  * return value indicates whether the read/write succeeds without a fatal
@@ -419,7 +425,7 @@ TEST_F(guard_pages, process_madvise)
 	ASSERT_EQ(munmap(&ptr_region[99 * page_size], page_size), 0);

 	/* Now guard in one step. */
-	count = process_madvise(pidfd, vec, 6, MADV_GUARD_INSTALL, 0);
+	count = sys_process_madvise(pidfd, vec, 6, MADV_GUARD_INSTALL, 0);

 	/* OK we don't have permission to do this, skip. */
 	if (count == -1 && errno == EPERM)
@@ -440,7 +446,7 @@ TEST_F(guard_pages, process_madvise)
 	ASSERT_FALSE(try_read_write_buf(&ptr3[19 * page_size]));

 	/* Now do the same with unguard... */
-	count = process_madvise(pidfd, vec, 6, MADV_GUARD_REMOVE, 0);
+	count = sys_process_madvise(pidfd, vec, 6, MADV_GUARD_REMOVE, 0);

 	/* ...and everything should now succeed. */

diff --git a/tools/testing/selftests/mm/run_vmtests.sh b/tools/testing/selftests/mm/run_vmtests.sh
index 2fc290d9430c..00c3f07ea100 100755
--- a/tools/testing/selftests/mm/run_vmtests.sh
+++ b/tools/testing/selftests/mm/run_vmtests.sh
@@ -45,6 +45,8 @@ separated by spaces:
 	vmalloc smoke tests
 - hmm
 	hmm smoke tests
+- madv_guard
+	test madvise(2) MADV_GUARD_INSTALL and MADV_GUARD_REMOVE options
 - madv_populate
 	test memadvise(2) MADV_POPULATE_{READ,WRITE} options
 - memfd_secret
@@ -375,6 +377,9 @@ CATEGORY="mremap" run_test ./mremap_dontunmap

 CATEGORY="hmm" run_test bash ./test_hmm.sh smoke

+# MADV_GUARD_INSTALL and MADV_GUARD_REMOVE tests
+CATEGORY="madv_guard" run_test ./guard-pages
+
 # MADV_POPULATE_READ and MADV_POPULATE_WRITE tests
 CATEGORY="madv_populate" run_test ./madv_populate

--
2.43.0