From c23ea61726d57d11d5c16a0b7943da85b7bd9f3f Mon Sep 17 00:00:00 2001
From: Muhammad Usama Anjum <usama.anjum@collabora.com>
Date: Thu, 25 Jan 2024 20:46:07 +0500
Subject: [PATCH] selftests/mm: protection_keys: save/restore nr_hugepages
settings
Save and restore nr_hugepages before changing it during the test. A test
should not change system wide settings.
Link: https://lkml.kernel.org/r/20240125154608.720072-5-usama.anjum@collabora.com
Fixes: 5f23f6d082a9 ("x86/pkeys: Add self-tests")
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
tools/testing/selftests/mm/protection_keys.c | 34 ++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c
index 48dc151f8fca8..f822ae31af22e 100644
--- a/tools/testing/selftests/mm/protection_keys.c
+++ b/tools/testing/selftests/mm/protection_keys.c
@@ -54,6 +54,7 @@ int test_nr;
u64 shadow_pkey_reg;
int dprint_in_signal;
char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
+char buf[256];
void cat_into_file(char *str, char *file)
{
@@ -1744,6 +1745,38 @@ void pkey_setup_shadow(void)
shadow_pkey_reg = __read_pkey_reg();
}
+void restore_settings_atexit(void)
+{
+ cat_into_file(buf, "/proc/sys/vm/nr_hugepages");
+}
+
+void save_settings(void)
+{
+ int fd;
+ int err;
+
+ if (geteuid())
+ return;
+
+ fd = open("/proc/sys/vm/nr_hugepages", O_RDONLY);
+ if (fd < 0) {
+ fprintf(stderr, "error opening\n");
+ perror("error: ");
+ exit(__LINE__);
+ }
+
+ /* -1 to guarantee leaving the trailing \0 */
+ err = read(fd, buf, sizeof(buf)-1);
+ if (err < 0) {
+ fprintf(stderr, "error reading\n");
+ perror("error: ");
+ exit(__LINE__);
+ }
+
+ atexit(restore_settings_atexit);
+ close(fd);
+}
+
int main(void)
{
int nr_iterations = 22;
@@ -1751,6 +1784,7 @@ int main(void)
srand((unsigned int)time(NULL));
+ save_settings();
setup_handlers();
printf("has pkeys: %d\n", pkeys_supported);
--
2.30.2