qemu/bsd-user/signal-common.h

/*
 * Emulation of BSD signals
 *
 * Copyright (c) 2013 Stacey Son
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#ifndef SIGNAL_COMMON_H
#define SIGNAL_COMMON_H

/**
 * block_signals: block all signals while handling this guest syscall
 *
 * Block all signals, and arrange that the signal mask is returned to
 * its correct value for the guest before we resume execution of guest code.
 * If this function returns non-zero, then the caller should immediately
 * return -TARGET_ERESTARTSYS to the main loop, which will take the pending
 * signal and restart execution of the syscall.
 * If block_signals() returns zero, then the caller can continue with
 * emulation of the system call knowing that no signals can be taken
 * (and therefore that no race conditions will result).
 * This should only be called once, because if it is called a second time
 * it will always return non-zero. (Think of it like a mutex that can't
 * be recursively locked.)
 * Signals will be unblocked again by process_pending_signals().
 *
 * Return value: non-zero if there was a pending signal, zero if not.
 */
int block_signals(void); /* Returns non zero if signal pending */

long do_rt_sigreturn(CPUArchState *env);
int do_sigaction(int sig, const struct target_sigaction *act,
                struct target_sigaction *oact);
abi_long do_sigaltstack(abi_ulong uss_addr, abi_ulong uoss_addr, abi_ulong sp);
long do_sigreturn(CPUArchState *env, abi_ulong addr);
void force_sig_fault(int sig, int code, abi_ulong addr);
void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info);
int host_to_target_signal(int sig);
void host_to_target_sigset(target_sigset_t *d, const sigset_t *s);
void process_pending_signals(CPUArchState *env);
void queue_signal(CPUArchState *env, int sig, int si_type,
                  target_siginfo_t *info);
void signal_init(void);
void target_to_host_sigset(sigset_t *d, const target_sigset_t *s);

/*
 * Within QEMU the top 8 bits of si_code indicate which of the parts of the
 * union in target_siginfo is valid. This only applies between
 * host_to_target_siginfo_noswap() and tswap_siginfo(); it does not appear
 * either within host siginfo_t or in target_siginfo structures which we get
 * from the guest userspace program. Linux kernels use this internally, but BSD
 * kernels don't do this, but its a useful abstraction.
 *
 * The linux-user version of this uses the top 16 bits, but FreeBSD's SI_USER
 * and other signal independent SI_ codes have bit 16 set, so we only use the top
 * byte instead.
 *
 * For FreeBSD, we have si_pid, si_uid, si_status, and si_addr always. Linux and
 * {Open,Net}BSD have a different approach (where their reason field is larger,
 * but whose siginfo has fewer fields always).
 *
 * QEMU_SI_CAPSICUM is currently only FreeBSD 14 current only, so only define
 * it where _capsicum is available.
 */
#define QEMU_SI_NOINFO   0      /* nothing other than si_signo valid */
#define QEMU_SI_FAULT    1      /* _fault is valid in _reason */
#define QEMU_SI_TIMER    2      /* _timer is valid in _reason */
#define QEMU_SI_MESGQ    3      /* _mesgq is valid in _reason */
#define QEMU_SI_POLL     4      /* _poll is valid in _reason */
#if defined(__FreeBSD_version) && __FreeBSD_version >= 1400026
#define QEMU_SI_CAPSICUM 5      /* _capsicum is valid in _reason */
#endif

#endif