From: Weihong Zhang <weihong.zhang@xxxxxxxxx>
LAM is enabled per-thread and gets inherited on fork(2)/clone(2). exec()
reverts LAM status to the default disabled state.
There are two test scenarios:
- Fork test cases:
These cases were used to test the inheritance of LAM for per-thread,
Child process generated by fork() should inherit LAM feature from
parent process, Child process can get the LAM mode same as parent
process.
- Execve test cases:
Processes generated by execve() are different from processes
generated by fork(), these processes revert LAM status to disabled
status.
Signed-off-by: Weihong Zhang <weihong.zhang@xxxxxxxxx>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
tools/testing/selftests/x86/lam.c | 125 +++++++++++++++++++++++++++++-
1 file changed, 121 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/x86/lam.c b/tools/testing/selftests/x86/lam.c
index 52750ebd0887..ebabd4333b7d 100644
--- a/tools/testing/selftests/x86/lam.c
+++ b/tools/testing/selftests/x86/lam.c
@@ -37,8 +37,9 @@
#define FUNC_MMAP 0x4
#define FUNC_SYSCALL 0x8
#define FUNC_URING 0x10
+#define FUNC_INHERITE 0x20
-#define TEST_MASK 0x1f
+#define TEST_MASK 0x3f
#define LOW_ADDR (0x1UL << 30)
#define HIGH_ADDR (0x3UL << 48)
@@ -174,6 +175,28 @@ static unsigned long get_default_tag_bits(void)
return lam;
}
+/*
+ * Set tagged address and read back untag mask.
+ * check if the untag mask is expected.
+ */
+static int get_lam(void)
+{
+ uint64_t ptr = 0;
+ int ret = -1;
+ /* Get untagged mask */
+ if (syscall(SYS_arch_prctl, ARCH_GET_UNTAG_MASK, &ptr) == -1)
+ return -1;
+
+ /* Check mask returned is expected */
+ if (ptr == ~(LAM_U57_MASK))
+ ret = LAM_U57_BITS;
+ else if (ptr == -1ULL)
+ ret = LAM_NONE;
+
+
+ return ret;
+}
+
/* According to LAM mode, set metadata in high bits */
static uint64_t set_metadata(uint64_t src, unsigned long lam)
{
@@ -581,7 +604,7 @@ int do_uring(unsigned long lam)
switch (lam) {
case LAM_U57_BITS: /* Clear bits 62:57 */
- addr = (addr & ~(0x3fULL << 57));
+ addr = (addr & ~(LAM_U57_MASK));
break;
}
free((void *)addr);
@@ -632,6 +655,72 @@ static int fork_test(struct testcases *test)
return ret;
}
+static int handle_execve(struct testcases *test)
+{
+ int ret, child_ret;
+ int lam = test->lam;
+ pid_t pid;
+
+ pid = fork();
+ if (pid < 0) {
+ perror("Fork failed.");
+ ret = 1;
+ } else if (pid == 0) {
+ char path[PATH_MAX];
+
+ /* Set LAM mode in parent process */
+ if (set_lam(lam) != 0)
+ return 1;
+
+ /* Get current binary's path and the binary was run by execve */
+ if (readlink("/proc/self/exe", path, PATH_MAX) <= 0)
+ exit(-1);
+
+ /* run binary to get LAM mode and return to parent process */
+ if (execlp(path, path, "-t 0x0", NULL) < 0) {
+ perror("error on exec");
+ exit(-1);
+ }
+ } else {
+ wait(&child_ret);
+ ret = WEXITSTATUS(child_ret);
+ if (ret != LAM_NONE)
+ return 1;
+ }
+
+ return 0;
+}
+
+static int handle_inheritance(struct testcases *test)
+{
+ int ret, child_ret;
+ int lam = test->lam;
+ pid_t pid;
+
+ /* Set LAM mode in parent process */
+ if (set_lam(lam) != 0)
+ return 1;
+
+ pid = fork();
+ if (pid < 0) {
+ perror("Fork failed.");
+ return 1;
+ } else if (pid == 0) {
+ /* Set LAM mode in parent process */
+ int child_lam = get_lam();
+
+ exit(child_lam);
+ } else {
+ wait(&child_ret);
+ ret = WEXITSTATUS(child_ret);
+
+ if (lam != ret)
+ return 1;
+ }
+
+ return 0;
+}
+
static void run_test(struct testcases *test, int count)
{
int i, ret = 0;
@@ -740,11 +829,26 @@ static struct testcases mmap_cases[] = {
},
};
+static struct testcases inheritance_cases[] = {
+ {
+ .expected = 0,
+ .lam = LAM_U57_BITS,
+ .test_func = handle_inheritance,
+ .msg = "FORK: LAM_U57, child process should get LAM mode same as parent\n",
+ },
+ {
+ .expected = 0,
+ .lam = LAM_U57_BITS,
+ .test_func = handle_execve,
+ .msg = "EXECVE: LAM_U57, child process should get disabled LAM mode\n",
+ },
+};
+
static void cmd_help(void)
{
printf("usage: lam [-h] [-t test list]\n");
printf("\t-t test list: run tests specified in the test list, default:0x%x\n", TEST_MASK);
- printf("\t\t0x1:malloc; 0x2:max_bits; 0x4:mmap; 0x8:syscall; 0x10:io_uring.\n");
+ printf("\t\t0x1:malloc; 0x2:max_bits; 0x4:mmap; 0x8:syscall; 0x10:io_uring; 0x20:inherit;\n");
printf("\t-h: help\n");
}
@@ -764,7 +868,7 @@ int main(int argc, char **argv)
switch (c) {
case 't':
tests = strtoul(optarg, NULL, 16);
- if (!(tests & TEST_MASK)) {
+ if (tests && !(tests & TEST_MASK)) {
ksft_print_msg("Invalid argument!\n");
return -1;
}
@@ -778,6 +882,16 @@ int main(int argc, char **argv)
}
}
+ /*
+ * When tests is 0, it is not a real test case;
+ * the option used by test case(execve) to check the lam mode in
+ * process generated by execve, the process read back lam mode and
+ * check with lam mode in parent process.
+ */
+ if (!tests)
+ return (get_lam());
+
+ /* Run test cases */
if (tests & FUNC_MALLOC)
run_test(malloc_cases, ARRAY_SIZE(malloc_cases));
@@ -793,6 +907,9 @@ int main(int argc, char **argv)
if (tests & FUNC_URING)
run_test(uring_cases, ARRAY_SIZE(uring_cases));
+ if (tests & FUNC_INHERITE)
+ run_test(inheritance_cases, ARRAY_SIZE(inheritance_cases));
+
ksft_set_plan(tests_cnt);
return ksft_exit_pass();
--
2.39.1
