Commit 833c12ce authored by Weihong Zhang's avatar Weihong Zhang Committed by Dave Hansen
Browse files

selftests/x86/lam: Add inherit test cases for linear-address masking 



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: default avatarWeihong Zhang <weihong.zhang@intel.com>
Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarDave Hansen <dave.hansen@linux.intel.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20230312112612.31869-16-kirill.shutemov%40linux.intel.com
parent 72fd6d73

tools/testing/selftests/x86/lam.c

+121 −4
Original line number Diff line number Diff line
@@ -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();