diff options
Diffstat (limited to 'tools/testing/selftests/rseq/rseq.c')
| -rw-r--r-- | tools/testing/selftests/rseq/rseq.c | 168 |
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; +} |