v4.19.13 snapshot.
diff --git a/tools/testing/selftests/sigaltstack/.gitignore b/tools/testing/selftests/sigaltstack/.gitignore
new file mode 100644
index 0000000..35897b0
--- /dev/null
+++ b/tools/testing/selftests/sigaltstack/.gitignore
@@ -0,0 +1 @@
+sas
diff --git a/tools/testing/selftests/sigaltstack/Makefile b/tools/testing/selftests/sigaltstack/Makefile
new file mode 100644
index 0000000..f68fbf8
--- /dev/null
+++ b/tools/testing/selftests/sigaltstack/Makefile
@@ -0,0 +1,5 @@
+CFLAGS = -Wall
+TEST_GEN_PROGS = sas
+
+include ../lib.mk
+
diff --git a/tools/testing/selftests/sigaltstack/sas.c b/tools/testing/selftests/sigaltstack/sas.c
new file mode 100644
index 0000000..228c2ae
--- /dev/null
+++ b/tools/testing/selftests/sigaltstack/sas.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Stas Sergeev <stsp@users.sourceforge.net>
+ *
+ * test sigaltstack(SS_ONSTACK | SS_AUTODISARM)
+ * If that succeeds, then swapcontext() can be used inside sighandler safely.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <ucontext.h>
+#include <alloca.h>
+#include <string.h>
+#include <assert.h>
+#include <errno.h>
+
+#include "../kselftest.h"
+
+#ifndef SS_AUTODISARM
+#define SS_AUTODISARM (1U << 31)
+#endif
+
+static void *sstack, *ustack;
+static ucontext_t uc, sc;
+static const char *msg = "[OK]\tStack preserved";
+static const char *msg2 = "[FAIL]\tStack corrupted";
+struct stk_data {
+ char msg[128];
+ int flag;
+};
+
+void my_usr1(int sig, siginfo_t *si, void *u)
+{
+ char *aa;
+ int err;
+ stack_t stk;
+ struct stk_data *p;
+
+#if __s390x__
+ register unsigned long sp asm("%15");
+#else
+ register unsigned long sp asm("sp");
+#endif
+
+ if (sp < (unsigned long)sstack ||
+ sp >= (unsigned long)sstack + SIGSTKSZ) {
+ ksft_exit_fail_msg("SP is not on sigaltstack\n");
+ }
+ /* put some data on stack. other sighandler will try to overwrite it */
+ aa = alloca(1024);
+ assert(aa);
+ p = (struct stk_data *)(aa + 512);
+ strcpy(p->msg, msg);
+ p->flag = 1;
+ ksft_print_msg("[RUN]\tsignal USR1\n");
+ err = sigaltstack(NULL, &stk);
+ if (err) {
+ ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+ if (stk.ss_flags != SS_DISABLE)
+ ksft_test_result_fail("tss_flags=%x, should be SS_DISABLE\n",
+ stk.ss_flags);
+ else
+ ksft_test_result_pass(
+ "sigaltstack is disabled in sighandler\n");
+ swapcontext(&sc, &uc);
+ ksft_print_msg("%s\n", p->msg);
+ if (!p->flag) {
+ ksft_exit_skip("[RUN]\tAborting\n");
+ exit(EXIT_FAILURE);
+ }
+}
+
+void my_usr2(int sig, siginfo_t *si, void *u)
+{
+ char *aa;
+ struct stk_data *p;
+
+ ksft_print_msg("[RUN]\tsignal USR2\n");
+ aa = alloca(1024);
+ /* dont run valgrind on this */
+ /* try to find the data stored by previous sighandler */
+ p = memmem(aa, 1024, msg, strlen(msg));
+ if (p) {
+ ksft_test_result_fail("sigaltstack re-used\n");
+ /* corrupt the data */
+ strcpy(p->msg, msg2);
+ /* tell other sighandler that his data is corrupted */
+ p->flag = 0;
+ }
+}
+
+static void switch_fn(void)
+{
+ ksft_print_msg("[RUN]\tswitched to user ctx\n");
+ raise(SIGUSR2);
+ setcontext(&sc);
+}
+
+int main(void)
+{
+ struct sigaction act;
+ stack_t stk;
+ int err;
+
+ ksft_print_header();
+
+ sigemptyset(&act.sa_mask);
+ act.sa_flags = SA_ONSTACK | SA_SIGINFO;
+ act.sa_sigaction = my_usr1;
+ sigaction(SIGUSR1, &act, NULL);
+ act.sa_sigaction = my_usr2;
+ sigaction(SIGUSR2, &act, NULL);
+ sstack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+ if (sstack == MAP_FAILED) {
+ ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ err = sigaltstack(NULL, &stk);
+ if (err) {
+ ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+ if (stk.ss_flags == SS_DISABLE) {
+ ksft_test_result_pass(
+ "Initial sigaltstack state was SS_DISABLE\n");
+ } else {
+ ksft_exit_fail_msg("Initial sigaltstack state was %x; "
+ "should have been SS_DISABLE\n", stk.ss_flags);
+ return EXIT_FAILURE;
+ }
+
+ stk.ss_sp = sstack;
+ stk.ss_size = SIGSTKSZ;
+ stk.ss_flags = SS_ONSTACK | SS_AUTODISARM;
+ err = sigaltstack(&stk, NULL);
+ if (err) {
+ if (errno == EINVAL) {
+ ksft_exit_skip(
+ "[NOTE]\tThe running kernel doesn't support SS_AUTODISARM\n");
+ /*
+ * If test cases for the !SS_AUTODISARM variant were
+ * added, we could still run them. We don't have any
+ * test cases like that yet, so just exit and report
+ * success.
+ */
+ return 0;
+ } else {
+ ksft_exit_fail_msg(
+ "sigaltstack(SS_ONSTACK | SS_AUTODISARM) %s\n",
+ strerror(errno));
+ return EXIT_FAILURE;
+ }
+ }
+
+ ustack = mmap(NULL, SIGSTKSZ, PROT_READ | PROT_WRITE,
+ MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0);
+ if (ustack == MAP_FAILED) {
+ ksft_exit_fail_msg("mmap() - %s\n", strerror(errno));
+ return EXIT_FAILURE;
+ }
+ getcontext(&uc);
+ uc.uc_link = NULL;
+ uc.uc_stack.ss_sp = ustack;
+ uc.uc_stack.ss_size = SIGSTKSZ;
+ makecontext(&uc, switch_fn, 0);
+ raise(SIGUSR1);
+
+ err = sigaltstack(NULL, &stk);
+ if (err) {
+ ksft_exit_fail_msg("sigaltstack() - %s\n", strerror(errno));
+ exit(EXIT_FAILURE);
+ }
+ if (stk.ss_flags != SS_AUTODISARM) {
+ ksft_exit_fail_msg("ss_flags=%x, should be SS_AUTODISARM\n",
+ stk.ss_flags);
+ exit(EXIT_FAILURE);
+ }
+ ksft_test_result_pass(
+ "sigaltstack is still SS_AUTODISARM after signal\n");
+
+ ksft_exit_pass();
+ return 0;
+}