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, newsp: (unsigned long)stack + __STACK_SIZE,
159 parent_tidptr: &parent_tid, tls: 0, child_tidptr: &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}
247

source code of linux/tools/testing/selftests/arm64/abi/tpidr2.c