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

/*	$NetBSD: longjmp.c,v 1.5.2.1 2025/08/02 05:54:33 perseant 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.
 *
 * 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 <stddef.h>

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

#include "assym.h"
#include "sparc_longjmp.h"

/*
 * check that offsets in the above structures match their usage in the
 * setjmp() side of this setup.  a jmp_buf is the 12-word contents of
 * the sigcontext structure, plus 2 more words for g4 and g7.
 */
__CTASSERT(_SIZEOF_SC + _JB_G4 == offsetof(struct __jmp_buf,regs.g4));
__CTASSERT(_SIZEOF_SC + _JB_G7 == offsetof(struct __jmp_buf,regs.g7));
__CTASSERT(sizeof(jmp_buf) >= sizeof(struct __jmp_buf));

/*
 * Use setcontext to reload the stack pointer, program counter <pc,npc>, and
 * set the return value in %o0.  The %i and %l registers will be reloaded
 * from the place to which %sp points.
 */
void
__longjmp14(jmp_buf env, int val)
{
	struct __jmp_buf *context = (void *)env;
	struct sigcontext *sc = &context->sc;
	struct __jmp_buf_regs_t *r = &context->regs;
	ucontext_t uc;

	/* Ensure non-zero SP */
	if (sc->sc_sp == 0)
		goto err;

	/* Initialise the context */
	memset(&uc, 0, sizeof(uc));

	/*
	 * 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);

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

	/* Extract PSR, PC, NPC and SP from jmp_buf */
	uc.uc_mcontext.__gregs[_REG_PSR] = sc->sc_psr;
	uc.uc_mcontext.__gregs[_REG_PC] = sc->sc_pc;
	uc.uc_mcontext.__gregs[_REG_nPC] = sc->sc_pc+4;
	uc.uc_mcontext.__gregs[_REG_O6] = sc->sc_sp;
	uc.uc_mcontext.__gregs[_REG_G2] = sc->sc_g1;
	uc.uc_mcontext.__gregs[_REG_G3] = sc->sc_npc;
	uc.uc_mcontext.__gregs[_REG_G4] = r->g4;
	uc.uc_mcontext.__gregs[_REG_G7] = r->g7;

	/* Set the return value; make sure it's non-zero */
	uc.uc_mcontext.__gregs[_REG_O0] = (val != 0 ? val : 1);

	setcontext(&uc);

err:
	longjmperror();
	abort();
	/* NOTREACHED */
}