tpidr2.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2
  3#include <linux/sched.h>
  4#include <linux/wait.h>
  5
  6#include "kselftest.h"
  7
  8#define SYS_TPIDR2 "S3_3_C13_C0_5"
  9
 10#define EXPECTED_TESTS 5
 11
 12static void set_tpidr2(uint64_t val)
 13{
 14	asm volatile (
 15		"msr	" SYS_TPIDR2 ", %0\n"
 16		:
 17		: "r"(val)
 18		: "cc");
 19}
 20
 21static uint64_t get_tpidr2(void)
 22{
 23	uint64_t val;
 24
 25	asm volatile (
 26		"mrs	%0, " SYS_TPIDR2 "\n"
 27		: "=r"(val)
 28		:
 29		: "cc");
 30
 31	return val;
 32}
 33
 34/* Processes should start with TPIDR2 == 0 */
 35static int default_value(void)
 36{
 37	return get_tpidr2() == 0;
 38}
 39
 40/* If we set TPIDR2 we should read that value */
 41static int write_read(void)
 42{
 43	set_tpidr2(getpid());
 44
 45	return getpid() == get_tpidr2();
 46}
 47
 48/* If we set a value we should read the same value after scheduling out */
 49static int write_sleep_read(void)
 50{
 51	set_tpidr2(getpid());
 52
 53	msleep(100);
 54
 55	return getpid() == get_tpidr2();
 56}
 57
 58/*
 59 * If we fork the value in the parent should be unchanged and the
 60 * child should start with the same value and be able to set its own
 61 * value.
 62 */
 63static int write_fork_read(void)
 64{
 65	pid_t newpid, waiting, oldpid;
 66	int status;
 67
 68	set_tpidr2(getpid());
 69
 70	oldpid = getpid();
 71	newpid = fork();
 72	if (newpid == 0) {
 73		/* In child */
 74		if (get_tpidr2() != oldpid) {
 75			ksft_print_msg("TPIDR2 changed in child: %llx\n",
 76				       get_tpidr2());
 77			exit(0);
 78		}
 79
 80		set_tpidr2(getpid());
 81		if (get_tpidr2() == getpid()) {
 82			exit(1);
 83		} else {
 84			ksft_print_msg("Failed to set TPIDR2 in child\n");
 85			exit(0);
 86		}
 87	}
 88	if (newpid < 0) {
 89		ksft_print_msg("fork() failed: %d\n", newpid);
 90		return 0;
 91	}
 92
 93	for (;;) {
 94		waiting = waitpid(newpid, &status, 0);
 95
 96		if (waiting < 0) {
 97			if (errno == EINTR)
 98				continue;
 99			ksft_print_msg("waitpid() failed: %d\n", errno);
100			return 0;
101		}
102		if (waiting != newpid) {
103			ksft_print_msg("waitpid() returned wrong PID: %d != %d\n",
104				       waiting, newpid);
105			return 0;
106		}
107
108		if (!WIFEXITED(status)) {
109			ksft_print_msg("child did not exit\n");
110			return 0;
111		}
112
113		if (getpid() != get_tpidr2()) {
114			ksft_print_msg("TPIDR2 corrupted in parent\n");
115			return 0;
116		}
117
118		return WEXITSTATUS(status);
119	}
120}
121
122/*
123 * sys_clone() has a lot of per architecture variation so just define
124 * it here rather than adding it to nolibc, plus the raw API is a
125 * little more convenient for this test.
126 */
127static int sys_clone(unsigned long clone_flags, unsigned long newsp,
128		     int *parent_tidptr, unsigned long tls,
129		     int *child_tidptr)
130{
131	return my_syscall5(__NR_clone, clone_flags, newsp, parent_tidptr, tls,
132			   child_tidptr);
133}
134
135#define __STACK_SIZE (8 * 1024 * 1024)
136
137/*
138 * If we clone with CLONE_VM then the value in the parent should
139 * be unchanged and the child should start with zero and be able to
140 * set its own value.
141 */
142static int write_clone_read(void)
143{
144	int parent_tid, child_tid;
145	pid_t parent, waiting;
146	int ret, status;
147	void *stack;
148
149	parent = getpid();
150	set_tpidr2(parent);
151
152	stack = malloc(__STACK_SIZE);
153	if (!stack) {
154		ksft_print_msg("malloc() failed\n");
155		return 0;
156	}
157
158	ret = sys_clone(CLONE_VM, (unsigned long)stack + __STACK_SIZE,
159			&parent_tid, 0, &child_tid);
160	if (ret == -1) {
161		ksft_print_msg("clone() failed: %d\n", errno);
162		return 0;
163	}
164
165	if (ret == 0) {
166		/* In child */
167		if (get_tpidr2() != 0) {
168			ksft_print_msg("TPIDR2 non-zero in child: %llx\n",
169				       get_tpidr2());
170			exit(0);
171		}
172
173		if (gettid() == 0)
174			ksft_print_msg("Child TID==0\n");
175		set_tpidr2(gettid());
176		if (get_tpidr2() == gettid()) {
177			exit(1);
178		} else {
179			ksft_print_msg("Failed to set TPIDR2 in child\n");
180			exit(0);
181		}
182	}
183
184	for (;;) {
185		waiting = waitpid(ret, &status, __WCLONE);
186
187		if (waiting < 0) {
188			if (errno == EINTR)
189				continue;
190			ksft_print_msg("waitpid() failed: %d\n", errno);
191			return 0;
192		}
193		if (waiting != ret) {
194			ksft_print_msg("waitpid() returned wrong PID %d\n",
195				       waiting);
196			return 0;
197		}
198
199		if (!WIFEXITED(status)) {
200			ksft_print_msg("child did not exit\n");
201			return 0;
202		}
203
204		if (parent != get_tpidr2()) {
205			ksft_print_msg("TPIDR2 corrupted in parent\n");
206			return 0;
207		}
208
209		return WEXITSTATUS(status);
210	}
211}
212
213int main(int argc, char **argv)
214{
215	int ret;
216
217	ksft_print_header();
218	ksft_set_plan(5);
219
220	ksft_print_msg("PID: %d\n", getpid());
221
222	/*
223	 * This test is run with nolibc which doesn't support hwcap and
224	 * it's probably disproportionate to implement so instead check
225	 * for the default vector length configuration in /proc.
226	 */
227	ret = open("/proc/sys/abi/sme_default_vector_length", O_RDONLY, 0);
228	if (ret >= 0) {
229		ksft_test_result(default_value(), "default_value\n");
230		ksft_test_result(write_read(), "write_read\n");
231		ksft_test_result(write_sleep_read(), "write_sleep_read\n");
232		ksft_test_result(write_fork_read(), "write_fork_read\n");
233		ksft_test_result(write_clone_read(), "write_clone_read\n");
234
235	} else {
236		ksft_print_msg("SME support not present\n");
237
238		ksft_test_result_skip("default_value\n");
239		ksft_test_result_skip("write_read\n");
240		ksft_test_result_skip("write_sleep_read\n");
241		ksft_test_result_skip("write_fork_read\n");
242		ksft_test_result_skip("write_clone_read\n");
243	}
244
245	ksft_finished();
246}