xref: /src/lib/libc/arch/mips/gen/longjmp.c

/*	$NetBSD: longjmp.c,v 1.7 2025/04/24 01:47:55 riastradh Exp $	*/

/*-
 * Copyright (c) 2003 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Christian Limpach and Matt Thomas.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "namespace.h"
#include <sys/types.h>
#include <ucontext.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>

#include <machine/regnum.h>

#define __LIBC12_SOURCE__
#include <setjmp.h>
#include <compat/include/setjmp.h>

void
__longjmp14(jmp_buf env, int val)
{
	struct sigcontext *sc = (void *)env;
	ucontext_t uc;

	/* Ensure non-zero SP and sigcontext magic number is present */
	if (sc->sc_regs[_R_SP] == 0 || sc->sc_regs[_R_ZERO] != (__register_t)0xACEDBADEU)
		goto err;

	/* Ensure non-zero return value */
	if (val == 0)
		val = 1;

	/*
	 * Set _UC_CPU (restore CPU registers) and _UC_SIGMASK (restore
	 * the signal mask) unconditionally.
	 *
	 * In the distant past of SA-based libpthread with sigprocmask
	 * interception, we called sigprocmask here instead of using
	 * _UC_SIGMASK -- but that restored the signal mask before the
	 * stack pointer (PR lib/57946: longjmp fails to restore stack
	 * first before restoring signal mask on most architectures),
	 * which breaks sigaltstack, and SA-based libpthread is long
	 * gone.  So we use _UC_SIGMASK.
	 *
	 * Set _UC_{SET,CLR}STACK according to SS_ONSTACK.
	 */
	uc.uc_flags = _UC_CPU | _UC_SIGMASK;
	uc.uc_flags |= (sc->sc_onstack ? _UC_SETSTACK : _UC_CLRSTACK);

	/* Clear uc_link */
	uc.uc_link = 0;

	/* Copy signal mask */
	uc.uc_sigmask = sc->sc_mask;

	/* Save return value in context */
	uc.uc_mcontext.__gregs[_REG_V0] = val;

	/* Copy saved registers */
	uc.uc_mcontext.__gregs[_REG_S0] = sc->sc_regs[_R_S0];
	uc.uc_mcontext.__gregs[_REG_S1] = sc->sc_regs[_R_S1];
	uc.uc_mcontext.__gregs[_REG_S2] = sc->sc_regs[_R_S2];
	uc.uc_mcontext.__gregs[_REG_S3] = sc->sc_regs[_R_S3];
	uc.uc_mcontext.__gregs[_REG_S4] = sc->sc_regs[_R_S4];
	uc.uc_mcontext.__gregs[_REG_S5] = sc->sc_regs[_R_S5];
	uc.uc_mcontext.__gregs[_REG_S6] = sc->sc_regs[_R_S6];
	uc.uc_mcontext.__gregs[_REG_S7] = sc->sc_regs[_R_S7];
	uc.uc_mcontext.__gregs[_REG_S8] = sc->sc_regs[_R_S8];
#if defined(__mips_n32) || defined(__mips_n64)
	uc.uc_mcontext.__gregs[_REG_GP] = sc->sc_regs[_R_GP];
#endif
	uc.uc_mcontext.__gregs[_REG_SP] = sc->sc_regs[_R_SP];
	uc.uc_mcontext.__gregs[_REG_RA] = sc->sc_regs[_R_RA];
	uc.uc_mcontext.__gregs[_REG_EPC] = sc->sc_pc;

	/* Copy FP state */
	if (sc->sc_fpused) {
		/* FP saved regs are $f20 .. $f31 */
		memcpy(&uc.uc_mcontext.__fpregs.__fp_r.__fp_regs[20],
		    &sc->sc_fpregs[20], 32 - 20);
		uc.uc_mcontext.__fpregs.__fp_csr =
		    sc->sc_fpregs[_R_FSR - _FPBASE];
		/* XXX sc_fp_control */
		uc.uc_flags |= _UC_FPU;
	}

	setcontext(&uc);
 err:
	longjmperror();
	abort();
	/* NOTREACHED */
}