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156 lines
3.2 KiB
156 lines
3.2 KiB
// SPDX-License-Identifier: LGPL-2.1 |
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/* |
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* rseq.c |
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* |
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* Copyright (C) 2016 Mathieu Desnoyers <[email protected]> |
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* |
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* This library is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; only |
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* version 2.1 of the License. |
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* |
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* This library is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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*/ |
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#define _GNU_SOURCE |
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#include <errno.h> |
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#include <sched.h> |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include <unistd.h> |
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#include <syscall.h> |
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#include <assert.h> |
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#include <signal.h> |
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#include <limits.h> |
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#include "rseq.h" |
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#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])) |
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__thread volatile struct rseq __rseq_abi = { |
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.cpu_id = RSEQ_CPU_ID_UNINITIALIZED, |
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}; |
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/* |
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* Shared with other libraries. This library may take rseq ownership if it is |
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* still 0 when executing the library constructor. Set to 1 by library |
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* constructor when handling rseq. Set to 0 in destructor if handling rseq. |
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*/ |
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int __rseq_handled; |
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/* Whether this library have ownership of rseq registration. */ |
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static int rseq_ownership; |
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static __thread volatile uint32_t __rseq_refcount; |
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static void signal_off_save(sigset_t *oldset) |
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{ |
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sigset_t set; |
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int ret; |
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sigfillset(&set); |
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ret = pthread_sigmask(SIG_BLOCK, &set, oldset); |
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if (ret) |
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abort(); |
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} |
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static void signal_restore(sigset_t oldset) |
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{ |
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int ret; |
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ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL); |
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if (ret) |
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abort(); |
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} |
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static int sys_rseq(volatile struct rseq *rseq_abi, uint32_t rseq_len, |
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int flags, uint32_t sig) |
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{ |
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return syscall(__NR_rseq, rseq_abi, rseq_len, flags, sig); |
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} |
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int rseq_register_current_thread(void) |
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{ |
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int rc, ret = 0; |
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sigset_t oldset; |
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if (!rseq_ownership) |
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return 0; |
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signal_off_save(&oldset); |
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if (__rseq_refcount == UINT_MAX) { |
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ret = -1; |
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goto end; |
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} |
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if (__rseq_refcount++) |
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goto end; |
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rc = sys_rseq(&__rseq_abi, sizeof(struct rseq), 0, RSEQ_SIG); |
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if (!rc) { |
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assert(rseq_current_cpu_raw() >= 0); |
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goto end; |
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} |
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if (errno != EBUSY) |
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__rseq_abi.cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED; |
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ret = -1; |
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__rseq_refcount--; |
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end: |
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signal_restore(oldset); |
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return ret; |
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} |
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int rseq_unregister_current_thread(void) |
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{ |
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int rc, ret = 0; |
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sigset_t oldset; |
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if (!rseq_ownership) |
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return 0; |
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signal_off_save(&oldset); |
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if (!__rseq_refcount) { |
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ret = -1; |
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goto end; |
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} |
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if (--__rseq_refcount) |
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goto end; |
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rc = sys_rseq(&__rseq_abi, sizeof(struct rseq), |
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RSEQ_FLAG_UNREGISTER, RSEQ_SIG); |
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if (!rc) |
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goto end; |
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__rseq_refcount = 1; |
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ret = -1; |
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end: |
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signal_restore(oldset); |
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return ret; |
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} |
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int32_t rseq_fallback_current_cpu(void) |
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{ |
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int32_t cpu; |
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cpu = sched_getcpu(); |
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if (cpu < 0) { |
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perror("sched_getcpu()"); |
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abort(); |
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} |
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return cpu; |
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} |
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void __attribute__((constructor)) rseq_init(void) |
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{ |
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/* Check whether rseq is handled by another library. */ |
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if (__rseq_handled) |
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return; |
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__rseq_handled = 1; |
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rseq_ownership = 1; |
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} |
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void __attribute__((destructor)) rseq_fini(void) |
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{ |
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if (!rseq_ownership) |
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return; |
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__rseq_handled = 0; |
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rseq_ownership = 0; |
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}
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