summaryrefslogtreecommitdiffstats
path: root/tools/testing/selftests/rseq/rseq.c
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /tools/testing/selftests/rseq/rseq.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/testing/selftests/rseq/rseq.c')
-rw-r--r--tools/testing/selftests/rseq/rseq.c168
1 files changed, 168 insertions, 0 deletions
diff --git a/tools/testing/selftests/rseq/rseq.c b/tools/testing/selftests/rseq/rseq.c
new file mode 100644
index 000000000..e20191fb4
--- /dev/null
+++ b/tools/testing/selftests/rseq/rseq.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: LGPL-2.1
+/*
+ * rseq.c
+ *
+ * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; only
+ * version 2.1 of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <syscall.h>
+#include <assert.h>
+#include <signal.h>
+#include <limits.h>
+#include <dlfcn.h>
+#include <stddef.h>
+
+#include <linux/compiler.h>
+
+#include "../kselftest.h"
+#include "rseq.h"
+
+/*
+ * Define weak versions to play nice with binaries that are statically linked
+ * against a libc that doesn't support registering its own rseq.
+ */
+__weak ptrdiff_t __rseq_offset;
+__weak unsigned int __rseq_size;
+__weak unsigned int __rseq_flags;
+
+static const ptrdiff_t *libc_rseq_offset_p = &__rseq_offset;
+static const unsigned int *libc_rseq_size_p = &__rseq_size;
+static const unsigned int *libc_rseq_flags_p = &__rseq_flags;
+
+/* Offset from the thread pointer to the rseq area. */
+ptrdiff_t rseq_offset;
+
+/* Size of the registered rseq area. 0 if the registration was
+ unsuccessful. */
+unsigned int rseq_size = -1U;
+
+/* Flags used during rseq registration. */
+unsigned int rseq_flags;
+
+static int rseq_ownership;
+
+static
+__thread struct rseq_abi __rseq_abi __attribute__((tls_model("initial-exec"))) = {
+ .cpu_id = RSEQ_ABI_CPU_ID_UNINITIALIZED,
+};
+
+static int sys_rseq(struct rseq_abi *rseq_abi, uint32_t rseq_len,
+ int flags, uint32_t sig)
+{
+ return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig);
+}
+
+int rseq_available(void)
+{
+ int rc;
+
+ rc = sys_rseq(NULL, 0, 0, 0);
+ if (rc != -1)
+ abort();
+ switch (errno) {
+ case ENOSYS:
+ return 0;
+ case EINVAL:
+ return 1;
+ default:
+ abort();
+ }
+}
+
+int rseq_register_current_thread(void)
+{
+ int rc;
+
+ if (!rseq_ownership) {
+ /* Treat libc's ownership as a successful registration. */
+ return 0;
+ }
+ rc = sys_rseq(&__rseq_abi, sizeof(struct rseq_abi), 0, RSEQ_SIG);
+ if (rc)
+ return -1;
+ assert(rseq_current_cpu_raw() >= 0);
+ return 0;
+}
+
+int rseq_unregister_current_thread(void)
+{
+ int rc;
+
+ if (!rseq_ownership) {
+ /* Treat libc's ownership as a successful unregistration. */
+ return 0;
+ }
+ rc = sys_rseq(&__rseq_abi, sizeof(struct rseq_abi), RSEQ_ABI_FLAG_UNREGISTER, RSEQ_SIG);
+ if (rc)
+ return -1;
+ return 0;
+}
+
+static __attribute__((constructor))
+void rseq_init(void)
+{
+ /*
+ * If the libc's registered rseq size isn't already valid, it may be
+ * because the binary is dynamically linked and not necessarily due to
+ * libc not having registered a restartable sequence. Try to find the
+ * symbols if that's the case.
+ */
+ if (!*libc_rseq_size_p) {
+ libc_rseq_offset_p = dlsym(RTLD_NEXT, "__rseq_offset");
+ libc_rseq_size_p = dlsym(RTLD_NEXT, "__rseq_size");
+ libc_rseq_flags_p = dlsym(RTLD_NEXT, "__rseq_flags");
+ }
+ if (libc_rseq_size_p && libc_rseq_offset_p && libc_rseq_flags_p &&
+ *libc_rseq_size_p != 0) {
+ /* rseq registration owned by glibc */
+ rseq_offset = *libc_rseq_offset_p;
+ rseq_size = *libc_rseq_size_p;
+ rseq_flags = *libc_rseq_flags_p;
+ return;
+ }
+ if (!rseq_available())
+ return;
+ rseq_ownership = 1;
+ rseq_offset = (void *)&__rseq_abi - rseq_thread_pointer();
+ rseq_size = sizeof(struct rseq_abi);
+ rseq_flags = 0;
+}
+
+static __attribute__((destructor))
+void rseq_exit(void)
+{
+ if (!rseq_ownership)
+ return;
+ rseq_offset = 0;
+ rseq_size = -1U;
+ rseq_ownership = 0;
+}
+
+int32_t rseq_fallback_current_cpu(void)
+{
+ int32_t cpu;
+
+ cpu = sched_getcpu();
+ if (cpu < 0) {
+ perror("sched_getcpu()");
+ abort();
+ }
+ return cpu;
+}