// 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 <mathieu.desnoyers@efficios.com>
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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 "rseq.h"
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#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
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__attribute__((tls_model("initial-exec"))) __thread
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volatile struct rseq __rseq_abi = {
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.cpu_id = RSEQ_CPU_ID_UNINITIALIZED,
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};
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static __attribute__((tls_model("initial-exec"))) __thread
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volatile int 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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signal_off_save(&oldset);
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if (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 = -2;
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ret = -1;
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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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signal_off_save(&oldset);
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if (--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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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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