1 // SPDX-License-Identifier: GPL-2.0
3 * Stas Sergeev <stsp@users.sourceforge.net>
5 * test sigaltstack(SS_ONSTACK | SS_AUTODISARM)
6 * If that succeeds, then swapcontext() can be used inside sighandler safely.
21 #include "../kselftest.h"
24 #define SS_AUTODISARM (1U << 31)
27 static void *sstack, *ustack;
28 static ucontext_t uc, sc;
29 static const char *msg = "[OK]\tStack preserved";
30 static const char *msg2 = "[FAIL]\tStack corrupted";
36 void my_usr1(int sig, siginfo_t *si, void *u)
44 register unsigned long sp asm("%15");
46 register unsigned long sp asm("sp");
49 if (sp < (unsigned long)sstack ||
50 sp >= (unsigned long)sstack + SIGSTKSZ) {
51 ksft_exit_fail_msg("SP is not on sigaltstack\n");
53 /* put some data on stack. other sighandler will try to overwrite it */
56 p = (struct stk_data *)(aa + 512);
59 ksft_print_msg("[RUN]\tsignal USR1\n");
60 err = sigaltstack(NULL, &stk);
62 ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
65 if (stk.ss_flags != SS_DISABLE)
66 ksft_test_result_fail("tss_flags=%x, should be SS_DISABLE\n",
69 ksft_test_result_pass(
70 "sigaltstack is disabled in sighandler\n");
71 swapcontext(&sc, &uc);
72 ksft_print_msg("%s\n", p->msg);
74 ksft_exit_skip("[RUN]\tAborting\n");
79 void my_usr2(int sig, siginfo_t *si, void *u)
84 ksft_print_msg("[RUN]\tsignal USR2\n");
86 /* dont run valgrind on this */
87 /* try to find the data stored by previous sighandler */
88 p = memmem(aa, 1024, msg, strlen(msg));
90 ksft_test_result_fail("sigaltstack re-used\n");
91 /* corrupt the data */
93 /* tell other sighandler that his data is corrupted */
98 static void switch_fn(void)
100 ksft_print_msg("[RUN]\tswitched to user ctx\n");
107 struct sigaction act;
113 sigemptyset(&act.sa_mask);
114 act.sa_flags = SA_ONSTACK | SA_SIGINFO;
115 act.sa_sigaction = my_usr1;
116 sigaction(SIGUSR1, &act, NULL);
117 act.sa_sigaction = my_usr2;
118 sigaction(SIGUSR2, &act, NULL);
119 sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
120 MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
121 if (sstack == MAP_FAILED) {
122 ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
126 err = sigaltstack(NULL, &stk);
128 ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
131 if (stk.ss_flags == SS_DISABLE) {
132 ksft_test_result_pass(
133 "Initial sigaltstack state was SS_DISABLE\n");
135 ksft_exit_fail_msg("Initial sigaltstack state was %x; "
136 "should have been SS_DISABLE\n", stk.ss_flags);
141 stk.ss_size = SIGSTKSZ;
142 stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;
143 err = sigaltstack(&stk, NULL);
145 if (errno == EINVAL) {
147 "[NOTE]\tThe running kernel doesn't support SS_AUTODISARM\n");
149 * If test cases for the !SS_AUTODISARM variant were
150 * added, we could still run them. We don't have any
151 * test cases like that yet, so just exit and report
157 "sigaltstack(SS_ONSTACK | SS_AUTODISARM) %s\n",
163 ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
164 MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
165 if (ustack == MAP_FAILED) {
166 ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
171 uc.uc_stack.ss_sp = ustack;
172 uc.uc_stack.ss_size = SIGSTKSZ;
173 makecontext(&uc, switch_fn, 0);
176 err = sigaltstack(NULL, &stk);
178 ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
181 if (stk.ss_flags != SS_AUTODISARM) {
182 ksft_exit_fail_msg("ss_flags=%x, should be SS_AUTODISARM\n",
186 ksft_test_result_pass(
187 "sigaltstack is still SS_AUTODISARM after signal\n");