15206 setcontext(2) should not restore %fsbase

Reviewed by: Robert Mustacchi <rm+illumos@fingolfin.org>
Reviewed by: Toomas Soome <tsoome@me.com>
Approved by: Patrick Mooney <pmooney@pfmooney.com>

3 files changed, 111 insertions, 1 deletions

diff --git a/usr/src/test/os-tests/runfiles/default.run b/usr/src/test/os-tests/runfiles/default.run
index 7a4189cf48..de2b29f2f1 100644
--- a/usr/src/test/os-tests/runfiles/default.run
+++ b/usr/src/test/os-tests/runfiles/default.run
@@ -12,7 +12,7 @@
 #
 # Copyright (c) 2012 by Delphix. All rights reserved.
 # Copyright 2020 Joyent, Inc.
-# Copyright 2021 OmniOS Community Edition (OmniOSce) Association.
+# Copyright 2022 OmniOS Community Edition (OmniOSce) Association.
 # Copyright 2021 Tintri by DDN, Inc. All rights reserved.
 # Copyright 2022 Oxide Computer Company
 # Copyright 2022 MNX Cloud, Inc.
@@ -39,6 +39,9 @@ tests = ['poll_test', 'epoll_test']
 [/opt/os-tests/tests/clock_gettime.32]
 [/opt/os-tests/tests/clock_gettime.64]
 
+[/opt/os-tests/tests/ucontext.32]
+[/opt/os-tests/tests/ucontext.64]
+
 [/opt/os-tests/tests/secflags]
 user = root
 tests = ['secflags_aslr',
diff --git a/usr/src/test/os-tests/tests/Makefile b/usr/src/test/os-tests/tests/Makefile
index afa9df81ed..a30832e8ee 100644
--- a/usr/src/test/os-tests/tests/Makefile
+++ b/usr/src/test/os-tests/tests/Makefile
@@ -46,6 +46,7 @@ PROGS = \
 	clock_gettime \
 	eventfd \
 	odirectory \
+	ucontext \
 	writev
 
 CPPFLAGS += -D_REENTRANT
@@ -65,6 +66,9 @@ clock_gettime.32 :=	CSTD = $(CSTD_GNU99)
 clock_gettime.64 :=	LDLIBS64 += -lproc
 clock_gettime.64 :=	CSTD = $(CSTD_GNU99)
 
+ucontext.32 :=		SMOFF += unreachable
+ucontext.64 :=		SMOFF += unreachable
+
 writev.32 :=		CPPFLAGS += -D_FILE_OFFSET_BITS=64
 writev.32 :=		CSTD = $(CSTD_GNU99)
 writev.64 :=		CSTD = $(CSTD_GNU99)
diff --git a/usr/src/test/os-tests/tests/ucontext.c b/usr/src/test/os-tests/tests/ucontext.c
new file mode 100644
index 0000000000..a6e43941c1
--- /dev/null
+++ b/usr/src/test/os-tests/tests/ucontext.c
@@ -0,0 +1,103 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright 2022 OmniOS Community Edition (OmniOSce) Association.
+ */
+
+#include <atomic.h>
+#include <err.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <ucontext.h>
+#include <unistd.h>
+#include <sys/debug.h>
+#include <sys/types.h>
+
+static __thread uint64_t tlsvar;
+static ucontext_t ctx;
+static uint32_t failures;
+static pthread_t tid;
+
+#define	THREAD1_VALUE	0x1010
+#define	THREAD2_VALUE	0x0202
+
+void
+report(char *tag)
+{
+	pthread_t ltid = pthread_self();
+
+	printf("  %-14s: thread=%x, TLS variable=%x\n",
+	    tag, (uint_t)ltid, tlsvar);
+}
+
+void
+run(void)
+{
+	pthread_t ltid = pthread_self();
+
+	printf("Coroutine started from second thread\n");
+	report("coroutine");
+
+	if (ltid != tid) {
+		fprintf(stderr,
+		    "FAIL: coroutine thread ID is %x, expected %x\n",
+		    ltid, tid);
+		atomic_inc_32(&failures);
+	}
+
+	if (tlsvar != THREAD2_VALUE) {
+		fprintf(stderr,
+		    "FAIL: coroutine TLS variable is %x, expected %x\n",
+		    tlsvar, THREAD2_VALUE);
+		atomic_inc_32(&failures);
+	}
+}
+
+void *
+thread(void *arg __unused)
+{
+	tlsvar = THREAD2_VALUE;
+
+	report("second thread");
+	/*
+	 * setcontext() does not return if successful, checking the return
+	 * value upsets smatch.
+	 */
+	(void) setcontext(&ctx);
+	errx(EXIT_FAILURE, "setcontext() returned and should not have.");
+
+	return (NULL);
+}
+
+int
+main(void)
+{
+	char stk[SIGSTKSZ];
+	void *status;
+
+	tlsvar = THREAD1_VALUE;
+
+	report("main thread");
+
+	VERIFY0(getcontext(&ctx));
+	ctx.uc_link = NULL;
+	ctx.uc_stack.ss_sp = stk;
+	ctx.uc_stack.ss_size = sizeof (stk);
+	makecontext(&ctx, run, 0);
+
+	VERIFY0(pthread_create(&tid, NULL, thread, NULL));
+	VERIFY0(pthread_join(tid, &status));
+
+	return (failures == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
+}