diff --git a/tools/testing/selftests/arm64/mte/check_ksm_options.c b/tools/testing/selftests/arm64/mte/check_ksm_options.c index 866f0929b664..4855b737d550 100644 --- a/tools/testing/selftests/arm64/mte/check_ksm_options.c +++ b/tools/testing/selftests/arm64/mte/check_ksm_options.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -22,6 +23,20 @@ static size_t page_sz; static unsigned long ksm_sysfs[5]; +static bool has_merge_across_nodes; + +static bool merge_across_nodes_available(void) +{ + const char *path = PATH_KSM "merge_across_nodes"; + + if (!access(path, R_OK | W_OK)) + return true; + if (errno == ENOENT) + return false; + + ksft_exit_skip("Unable to read and write %s: %s\n", path, + strerror(errno)); +} static unsigned long read_sysfs(char *str) { @@ -56,8 +71,10 @@ static void write_sysfs(char *str, unsigned long val) static void mte_ksm_setup(void) { - ksm_sysfs[0] = read_sysfs(PATH_KSM "merge_across_nodes"); - write_sysfs(PATH_KSM "merge_across_nodes", 1); + if (has_merge_across_nodes) { + ksm_sysfs[0] = read_sysfs(PATH_KSM "merge_across_nodes"); + write_sysfs(PATH_KSM "merge_across_nodes", 1); + } ksm_sysfs[1] = read_sysfs(PATH_KSM "sleep_millisecs"); write_sysfs(PATH_KSM "sleep_millisecs", 0); ksm_sysfs[2] = read_sysfs(PATH_KSM "run"); @@ -70,7 +87,8 @@ static void mte_ksm_setup(void) static void mte_ksm_restore(void) { - write_sysfs(PATH_KSM "merge_across_nodes", ksm_sysfs[0]); + if (has_merge_across_nodes) + write_sysfs(PATH_KSM "merge_across_nodes", ksm_sysfs[0]); write_sysfs(PATH_KSM "sleep_millisecs", ksm_sysfs[1]); write_sysfs(PATH_KSM "run", ksm_sysfs[2]); write_sysfs(PATH_KSM "max_page_sharing", ksm_sysfs[3]); @@ -137,6 +155,11 @@ int main(int argc, char *argv[]) err = mte_default_setup(); if (err) return err; + + if (geteuid() != 0) + ksft_exit_skip("Please run the test as root\n"); + + has_merge_across_nodes = merge_across_nodes_available(); page_sz = getpagesize(); if (!page_sz) { ksft_print_msg("ERR: Unable to get page size\n");