signal.c

qemu虚拟机代码

/*
 *  Emulation of Linux signals
 * 
 *  Copyright (c) 2003 Fabrice Bellard
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <sys/ucontext.h>

#include "qemu.h"

//#define DEBUG_SIGNAL

#define MAX_SIGQUEUE_SIZE 1024

struct sigqueue {
    struct sigqueue *next;
    target_siginfo_t info;
};

struct emulated_sigaction {
    struct target_sigaction sa;
    int pending; /* true if signal is pending */
    struct sigqueue *first;
    struct sigqueue info; /* in order to always have memory for the
                             first signal, we put it here */
};

static struct emulated_sigaction sigact_table[TARGET_NSIG];
static struct sigqueue sigqueue_table[MAX_SIGQUEUE_SIZE]; /* siginfo queue */
static struct sigqueue *first_free; /* first free siginfo queue entry */
static int signal_pending; /* non zero if a signal may be pending */

static void host_signal_handler(int host_signum, siginfo_t *info, 
                                void *puc);

static uint8_t host_to_target_signal_table[65] = {
    [SIGHUP] = TARGET_SIGHUP,
    [SIGINT] = TARGET_SIGINT,
    [SIGQUIT] = TARGET_SIGQUIT,
    [SIGILL] = TARGET_SIGILL,
    [SIGTRAP] = TARGET_SIGTRAP,
    [SIGABRT] = TARGET_SIGABRT,
/*    [SIGIOT] = TARGET_SIGIOT,*/
    [SIGBUS] = TARGET_SIGBUS,
    [SIGFPE] = TARGET_SIGFPE,
    [SIGKILL] = TARGET_SIGKILL,
    [SIGUSR1] = TARGET_SIGUSR1,
    [SIGSEGV] = TARGET_SIGSEGV,
    [SIGUSR2] = TARGET_SIGUSR2,
    [SIGPIPE] = TARGET_SIGPIPE,
    [SIGALRM] = TARGET_SIGALRM,
    [SIGTERM] = TARGET_SIGTERM,
#ifdef SIGSTKFLT
    [SIGSTKFLT] = TARGET_SIGSTKFLT,
#endif
    [SIGCHLD] = TARGET_SIGCHLD,
    [SIGCONT] = TARGET_SIGCONT,
    [SIGSTOP] = TARGET_SIGSTOP,
    [SIGTSTP] = TARGET_SIGTSTP,
    [SIGTTIN] = TARGET_SIGTTIN,
    [SIGTTOU] = TARGET_SIGTTOU,
    [SIGURG] = TARGET_SIGURG,
    [SIGXCPU] = TARGET_SIGXCPU,
    [SIGXFSZ] = TARGET_SIGXFSZ,
    [SIGVTALRM] = TARGET_SIGVTALRM,
    [SIGPROF] = TARGET_SIGPROF,
    [SIGWINCH] = TARGET_SIGWINCH,
    [SIGIO] = TARGET_SIGIO,
    [SIGPWR] = TARGET_SIGPWR,
    [SIGSYS] = TARGET_SIGSYS,
    /* next signals stay the same */
};
static uint8_t target_to_host_signal_table[65];

static inline int host_to_target_signal(int sig)
{
    return host_to_target_signal_table[sig];
}

static inline int target_to_host_signal(int sig)
{
    return target_to_host_signal_table[sig];
}

static void host_to_target_sigset_internal(target_sigset_t *d, 
                                           const sigset_t *s)
{
    int i;
    unsigned long sigmask;
    uint32_t target_sigmask;
    
    sigmask = ((unsigned long *)s)[0];
    target_sigmask = 0;
    for(i = 0; i < 32; i++) {
        if (sigmask & (1 << i)) 
            target_sigmask |= 1 << (host_to_target_signal(i + 1) - 1);
    }
#if TARGET_LONG_BITS == 32 && HOST_LONG_BITS == 32
    d->sig[0] = target_sigmask;
    for(i = 1;i < TARGET_NSIG_WORDS; i++) {
        d->sig[i] = ((unsigned long *)s)[i];
    }
#elif TARGET_LONG_BITS == 32 && HOST_LONG_BITS == 64 && TARGET_NSIG_WORDS == 2
    d->sig[0] = target_sigmask;
    d->sig[1] = sigmask >> 32;
#else
#warning host_to_target_sigset
#endif
}

void host_to_target_sigset(target_sigset_t *d, const sigset_t *s)
{
    target_sigset_t d1;
    int i;

    host_to_target_sigset_internal(&d1, s);
    for(i = 0;i < TARGET_NSIG_WORDS; i++)
        d->sig[i] = tswapl(d1.sig[i]);
}

void target_to_host_sigset_internal(sigset_t *d, const target_sigset_t *s)
{
    int i;
    unsigned long sigmask;
    target_ulong target_sigmask;

    target_sigmask = s->sig[0];
    sigmask = 0;
    for(i = 0; i < 32; i++) {
        if (target_sigmask & (1 << i)) 
            sigmask |= 1 << (target_to_host_signal(i + 1) - 1);
    }
#if TARGET_LONG_BITS == 32 && HOST_LONG_BITS == 32
    ((unsigned long *)d)[0] = sigmask;
    for(i = 1;i < TARGET_NSIG_WORDS; i++) {
        ((unsigned long *)d)[i] = s->sig[i];
    }
#elif TARGET_LONG_BITS == 32 && HOST_LONG_BITS == 64 && TARGET_NSIG_WORDS == 2
    ((unsigned long *)d)[0] = sigmask | ((unsigned long)(s->sig[1]) << 32);
#else
#warning target_to_host_sigset
#endif /* TARGET_LONG_BITS */
}

void target_to_host_sigset(sigset_t *d, const target_sigset_t *s)
{
    target_sigset_t s1;
    int i;

    for(i = 0;i < TARGET_NSIG_WORDS; i++)
        s1.sig[i] = tswapl(s->sig[i]);
    target_to_host_sigset_internal(d, &s1);
}
    
void host_to_target_old_sigset(target_ulong *old_sigset, 
                               const sigset_t *sigset)
{
    target_sigset_t d;
    host_to_target_sigset(&d, sigset);
    *old_sigset = d.sig[0];
}

void target_to_host_old_sigset(sigset_t *sigset, 
                               const target_ulong *old_sigset)
{
    target_sigset_t d;
    int i;

    d.sig[0] = *old_sigset;
    for(i = 1;i < TARGET_NSIG_WORDS; i++)
        d.sig[i] = 0;
    target_to_host_sigset(sigset, &d);
}

/* siginfo conversion */

static inline void host_to_target_siginfo_noswap(target_siginfo_t *tinfo, 
                                                 const siginfo_t *info)
{
    int sig;
    sig = host_to_target_signal(info->si_signo);
    tinfo->si_signo = sig;
    tinfo->si_errno = 0;
    tinfo->si_code = 0;
    if (sig == SIGILL || sig == SIGFPE || sig == SIGSEGV || 
        sig == SIGBUS || sig == SIGTRAP) {
        /* should never come here, but who knows. The information for
           the target is irrelevant */
        tinfo->_sifields._sigfault._addr = 0;
    } else if (sig >= TARGET_SIGRTMIN) {
        tinfo->_sifields._rt._pid = info->si_pid;
        tinfo->_sifields._rt._uid = info->si_uid;
        /* XXX: potential problem if 64 bit */
        tinfo->_sifields._rt._sigval.sival_ptr = 
            (target_ulong)info->si_value.sival_ptr;
    }
}

static void tswap_siginfo(target_siginfo_t *tinfo, 
                          const target_siginfo_t *info)
{
    int sig;
    sig = info->si_signo;
    tinfo->si_signo = tswap32(sig);
    tinfo->si_errno = tswap32(info->si_errno);
    tinfo->si_code = tswap32(info->si_code);
    if (sig == SIGILL || sig == SIGFPE || sig == SIGSEGV || 
        sig == SIGBUS || sig == SIGTRAP) {
        tinfo->_sifields._sigfault._addr = 
            tswapl(info->_sifields._sigfault._addr);
    } else if (sig >= TARGET_SIGRTMIN) {
        tinfo->_sifields._rt._pid = tswap32(info->_sifields._rt._pid);
        tinfo->_sifields._rt._uid = tswap32(info->_sifields._rt._uid);
        tinfo->_sifields._rt._sigval.sival_ptr = 
            tswapl(info->_sifields._rt._sigval.sival_ptr);
    }
}


void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info)
{
    host_to_target_siginfo_noswap(tinfo, info);
    tswap_siginfo(tinfo, tinfo);
}

/* XXX: we support only POSIX RT signals are used. */
/* XXX: find a solution for 64 bit (additionnal malloced data is needed) */
void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo)
{
    info->si_signo = tswap32(tinfo->si_signo);
    info->si_errno = tswap32(tinfo->si_errno);
    info->si_code = tswap32(tinfo->si_code);
    info->si_pid = tswap32(tinfo->_sifields._rt._pid);
    info->si_uid = tswap32(tinfo->_sifields._rt._uid);
    info->si_value.sival_ptr = 
        (void *)tswapl(tinfo->_sifields._rt._sigval.sival_ptr);
}

void signal_init(void)
{
    struct sigaction act;
    int i, j;

    /* generate signal conversion tables */
    for(i = 1; i <= 64; i++) {
        if (host_to_target_signal_table[i] == 0)
            host_to_target_signal_table[i] = i;
    }
    for(i = 1; i <= 64; i++) {
        j = host_to_target_signal_table[i];
        target_to_host_signal_table[j] = i;
    }
        
    /* set all host signal handlers. ALL signals are blocked during
       the handlers to serialize them. */
    sigfillset(&act.sa_mask);
    act.sa_flags = SA_SIGINFO;
    act.sa_sigaction = host_signal_handler;
    for(i = 1; i < NSIG; i++) {
        sigaction(i, &act, NULL);
    }
    
    memset(sigact_table, 0, sizeof(sigact_table));

    first_free = &sigqueue_table[0];
    for(i = 0; i < MAX_SIGQUEUE_SIZE - 1; i++) 
        sigqueue_table[i].next = &sigqueue_table[i + 1];
    sigqueue_table[MAX_SIGQUEUE_SIZE - 1].next = NULL;
}

/* signal queue handling */

static inline struct sigqueue *alloc_sigqueue(void)
{
    struct sigqueue *q = first_free;
    if (!q)
        return NULL;
    first_free = q->next;
    return q;
}

static inline void free_sigqueue(struct sigqueue *q)
{
    q->next = first_free;
    first_free = q;
}

/* abort execution with signal */
void __attribute((noreturn)) force_sig(int sig)
{
    int host_sig;
    host_sig = target_to_host_signal(sig);
    fprintf(stderr, "qemu: uncaught target signal %d (%s) - exiting\n", 
            sig, strsignal(host_sig));
#if 1
    _exit(-host_sig);
#else
    {
        struct sigaction act;
        sigemptyset(&act.sa_mask);
        act.sa_flags = SA_SIGINFO;
        act.sa_sigaction = SIG_DFL;
        sigaction(SIGABRT, &act, NULL);
        abort();
    }
#endif
}

/* queue a signal so that it will be send to the virtual CPU as soon
   as possible */
int queue_signal(int sig, target_siginfo_t *info)
{
    struct emulated_sigaction *k;
    struct sigqueue *q, **pq;
    target_ulong handler;

#if defined(DEBUG_SIGNAL)
    fprintf(stderr, "queue_signal: sig=%d\n", 
            sig);
#endif
    k = &sigact_table[sig - 1];
    handler = k->sa._sa_handler;
    if (handler == TARGET_SIG_DFL) {
        /* default handler : ignore some signal. The other are fatal */
        if (sig != TARGET_SIGCHLD && 
            sig != TARGET_SIGURG && 
            sig != TARGET_SIGWINCH) {
            force_sig(sig);
        } else {
            return 0; /* indicate ignored */
        }
    } else if (handler == TARGET_SIG_IGN) {
        /* ignore signal */
        return 0;
    } else if (handler == TARGET_SIG_ERR) {
        force_sig(sig);
    } else {
        pq = &k->first;
        if (sig < TARGET_SIGRTMIN) {
            /* if non real time signal, we queue exactly one signal */
            if (!k->pending)
                q = &k->info;
            else
                return 0;
        } else {
            if (!k->pending) {
                /* first signal */
                q = &k->info;
            } else {
                q = alloc_sigqueue();
                if (!q)
                    return -EAGAIN;
                while (*pq != NULL)
                    pq = &(*pq)->next;
            }
        }
        *pq = q;
        q->info = *info;
        q->next = NULL;
        k->pending = 1;
        /* signal that a new signal is pending */
        signal_pending = 1;
        return 1; /* indicates that the signal was queued */
    }
}

static void host_signal_handler(int host_signum, siginfo_t *info, 
                                void *puc)
{
    int sig;
    target_siginfo_t tinfo;

    /* the CPU emulator uses some host signals to detect exceptions,
       we we forward to it some signals */
    if (host_signum == SIGSEGV || host_signum == SIGBUS 
#if defined(TARGET_I386) && defined(USE_CODE_COPY)
        || host_signum == SIGFPE
#endif
        ) {
        if (cpu_signal_handler(host_signum, info, puc))
            return;
    }

    /* get target signal number */
    sig = host_to_target_signal(host_signum);
    if (sig < 1 || sig > TARGET_NSIG)
        return;
#if defined(DEBUG_SIGNAL)
    fprintf(stderr, "qemu: got signal %d\n", sig);
#endif
    host_to_target_siginfo_noswap(&tinfo, info);
    if (queue_signal(sig, &tinfo) == 1) {
        /* interrupt the virtual CPU as soon as possible */
        cpu_interrupt(global_env, CPU_INTERRUPT_EXIT);
    }
}

int do_sigaction(int sig, const struct target_sigaction *act,
                 struct target_sigaction *oact)
{
    struct emulated_sigaction *k;
    struct sigaction act1;
    int host_sig;

    if (sig < 1 || sig > TARGET_NSIG)
        return -EINVAL;
    k = &sigact_table[sig - 1];
#if defined(DEBUG_SIGNAL)
    fprintf(stderr, "sigaction sig=%d act=0x%08x, oact=0x%08x\n", 
            sig, (int)act, (int)oact);
#endif
    if (oact) {
        oact->_sa_handler = tswapl(k->sa._sa_handler);
        oact->sa_flags = tswapl(k->sa.sa_flags);