selftests/rseq: Add rseq syscall errors test

This test adds coverage of expected errors during rseq registration and
unregistration, it disables glibc integration and will thus always
exercise the rseq syscall explictly.

Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20250121213402.1754762-1-mjeanson@efficios.com

diff --git a/tools/testing/selftests/rseq/.gitignore b/tools/testing/selftests/rseq/.gitignore
index 16496de5f6ce48a53f1836d4b220ba2e99fd0814..0fda241fa62b0295feef918a97f75061021f39c1 100644 (file)
--- a/tools/testing/selftests/rseq/.gitignore
+++ b/tools/testing/selftests/rseq/.gitignore
@@ -9,3 +9,4 @@ param_test_compare_twice
 param_test_mm_cid
 param_test_mm_cid_benchmark
 param_test_mm_cid_compare_twice
+syscall_errors_test

diff --git a/tools/testing/selftests/rseq/Makefile b/tools/testing/selftests/rseq/Makefile
index 5a3432fceb58671a2383a0385bee5ff0e11c0a09..0d0a5fae59547fead6c543a7cfef9af38839f009 100644 (file)
--- a/tools/testing/selftests/rseq/Makefile
+++ b/tools/testing/selftests/rseq/Makefile
@@ -16,11 +16,12 @@ OVERRIDE_TARGETS = 1
 
 TEST_GEN_PROGS = basic_test basic_percpu_ops_test basic_percpu_ops_mm_cid_test param_test \
                param_test_benchmark param_test_compare_twice param_test_mm_cid \
-               param_test_mm_cid_benchmark param_test_mm_cid_compare_twice
+               param_test_mm_cid_benchmark param_test_mm_cid_compare_twice \
+               syscall_errors_test
 
 TEST_GEN_PROGS_EXTENDED = librseq.so
 
-TEST_PROGS = run_param_test.sh
+TEST_PROGS = run_param_test.sh run_syscall_errors_test.sh
 
 TEST_FILES := settings
 
@@ -54,3 +55,7 @@ $(OUTPUT)/param_test_mm_cid_benchmark: param_test.c $(TEST_GEN_PROGS_EXTENDED) \
 $(OUTPUT)/param_test_mm_cid_compare_twice: param_test.c $(TEST_GEN_PROGS_EXTENDED) \
                                        rseq.h rseq-*.h
        $(CC) $(CFLAGS) -DBUILDOPT_RSEQ_PERCPU_MM_CID -DRSEQ_COMPARE_TWICE $< $(LDLIBS) -lrseq -o $@
+
+$(OUTPUT)/syscall_errors_test: syscall_errors_test.c $(TEST_GEN_PROGS_EXTENDED) \
+                                       rseq.h rseq-*.h
+       $(CC) $(CFLAGS) $< $(LDLIBS) -lrseq -o $@

diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
index f6156790c3b4dfaf85e7e196656fe1bf76539411..1e29db92094d8e5d505c5798caea5f30f2d6a231 100644 (file)
--- a/tools/testing/selftests/rseq/rseq.c
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -87,7 +87,7 @@ static int sys_getcpu(unsigned *cpu, unsigned *node)
        return syscall(__NR_getcpu, cpu, node, NULL);
 }
 
-int rseq_available(void)
+bool rseq_available(void)
 {
        int rc;
 
@@ -96,9 +96,9 @@ int rseq_available(void)
                abort();
        switch (errno) {
        case ENOSYS:
-               return 0;
+               return false;
        case EINVAL:
-               return 1;
+               return true;
        default:
                abort();
        }

diff --git a/tools/testing/selftests/rseq/rseq.h b/tools/testing/selftests/rseq/rseq.h
index ba424ce80a719f1d3725a59314371ccab889d2d5..f51a5fdb044431585cbc57b6ae07fa2f59aefe23 100644 (file)
--- a/tools/testing/selftests/rseq/rseq.h
+++ b/tools/testing/selftests/rseq/rseq.h
@@ -159,6 +159,11 @@ int32_t rseq_fallback_current_cpu(void);
  */
 int32_t rseq_fallback_current_node(void);
 
+/*
+ * Returns true if rseq is supported.
+ */
+bool rseq_available(void);
+
 /*
  * Values returned can be either the current CPU number, -1 (rseq is
  * uninitialized), or -2 (rseq initialization has failed).

diff --git a/tools/testing/selftests/rseq/run_syscall_errors_test.sh b/tools/testing/selftests/rseq/run_syscall_errors_test.sh
new file mode 100755 (executable)
index 0000000..9272246
--- /dev/null
+++ b/tools/testing/selftests/rseq/run_syscall_errors_test.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+# SPDX-License-Identifier: MIT
+# SPDX-FileCopyrightText: 2024 Michael Jeanson <mjeanson@efficios.com>
+
+GLIBC_TUNABLES="${GLIBC_TUNABLES:-}:glibc.pthread.rseq=0" ./syscall_errors_test

diff --git a/tools/testing/selftests/rseq/syscall_errors_test.c b/tools/testing/selftests/rseq/syscall_errors_test.c
new file mode 100644 (file)
index 0000000..a5d9e1f
--- /dev/null
+++ b/tools/testing/selftests/rseq/syscall_errors_test.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: MIT
+// SPDX-FileCopyrightText: 2024 Michael Jeanson <mjeanson@efficios.com>
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <assert.h>
+#include <stdint.h>
+#include <syscall.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "rseq.h"
+
+static int sys_rseq(void *rseq_abi, uint32_t rseq_len,
+                   int flags, uint32_t sig)
+{
+       return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
+}
+
+/*
+ * Check the value of errno on some expected failures of the rseq syscall.
+ */
+
+int main(void)
+{
+       struct rseq_abi *global_rseq = rseq_get_abi();
+       int ret;
+       int errno_copy;
+
+       if (!rseq_available()) {
+               fprintf(stderr, "rseq syscall unavailable");
+               goto error;
+       }
+
+       /* The current thread is NOT registered. */
+
+       /* EINVAL */
+       errno = 0;
+       ret = sys_rseq(global_rseq, 32, -1, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Registration with invalid flag fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret == 0 || errno_copy != EINVAL)
+               goto error;
+
+       errno = 0;
+       ret = sys_rseq((char *) global_rseq + 1, 32, 0, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Registration with unaligned rseq_abi fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret == 0 || errno_copy != EINVAL)
+               goto error;
+
+       errno = 0;
+       ret = sys_rseq(global_rseq, 31, 0, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Registration with invalid size fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret == 0 || errno_copy != EINVAL)
+               goto error;
+
+
+#if defined(__LP64__) && (!defined(__s390__) && !defined(__s390x__))
+       /*
+        * We haven't found a reliable way to find an invalid address when
+        * running a 32bit userspace on a 64bit kernel, so only run this test
+        * on 64bit builds for the moment.
+        *
+        * Also exclude architectures that select
+        * CONFIG_ALTERNATE_USER_ADDRESS_SPACE where the kernel and userspace
+        * have their own address space and this failure can't happen.
+        */
+
+       /* EFAULT */
+       errno = 0;
+       ret = sys_rseq((void *) -4096UL, 32, 0, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Registration with invalid address fails with errno set to EFAULT (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret == 0 || errno_copy != EFAULT)
+               goto error;
+#endif
+
+       errno = 0;
+       ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Registration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret != 0 && errno != 0)
+               goto error;
+
+       /* The current thread is registered. */
+
+       /* EBUSY */
+       errno = 0;
+       ret = sys_rseq(global_rseq, 32, 0, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Double registration fails with errno set to EBUSY (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret == 0 || errno_copy != EBUSY)
+               goto error;
+
+       /* EPERM */
+       errno = 0;
+       ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG + 1);
+       errno_copy = errno;
+       fprintf(stderr, "Unregistration with wrong RSEQ_SIG fails with errno to EPERM (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret == 0 || errno_copy != EPERM)
+               goto error;
+
+       errno = 0;
+       ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Unregistration succeeds for the current thread (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret != 0)
+               goto error;
+
+       errno = 0;
+       ret = sys_rseq(global_rseq, 32, RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
+       errno_copy = errno;
+       fprintf(stderr, "Double unregistration fails with errno set to EINVAL (ret = %d, errno = %s)\n", ret, strerrorname_np(errno_copy));
+       if (ret == 0 || errno_copy != EINVAL)
+               goto error;
+
+       return 0;
+error:
+       return -1;
+}