Archipelago » qemu

/*

 *  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 <signal.h>

#include <errno.h>

#include <sys/ucontext.h>

#include "gemu.h"

/* signal handling inspired from em86. */

//#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);

/* XXX: do it properly */

static inline int host_to_target_signal(int sig)

{

    return sig;

}

static inline int target_to_host_signal(int sig)

{

    return sig;

}

void host_to_target_sigset(target_sigset_t *d, sigset_t *s)

{

    int i;

    for(i = 0;i < TARGET_NSIG_WORDS; i++) {

        d->sig[i] = tswapl(((unsigned long *)s)[i]);

    }

}

void target_to_host_sigset(sigset_t *d, target_sigset_t *s)

{

    int i;

    for(i = 0;i < TARGET_NSIG_WORDS; i++) {

        ((unsigned long *)d)[i] = tswapl(s->sig[i]);

    }

}

void host_to_target_old_sigset(target_ulong *old_sigset, 

                               const sigset_t *sigset)

{

    *old_sigset = tswap32(*(unsigned long *)sigset & 0xffffffff);

}

void target_to_host_old_sigset(sigset_t *sigset, 

                               const target_ulong *old_sigset)

{

    sigemptyset(sigset);

    *(unsigned long *)sigset = tswapl(*old_sigset);

}

/* 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) {

        /* 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) {

        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;

    /* 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, "gemu: 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_sigal: 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 */

    }

}

#if defined(DEBUG_SIGNAL)

#ifdef __i386__

static void dump_regs(struct ucontext *uc)

{

    fprintf(stderr, 

            "EAX=%08x EBX=%08x ECX=%08x EDX=%08x\n"

            "ESI=%08x EDI=%08x EBP=%08x ESP=%08x\n"

            "EFL=%08x EIP=%08x\n",

            uc->uc_mcontext.gregs[EAX],

            uc->uc_mcontext.gregs[EBX],

            uc->uc_mcontext.gregs[ECX],

            uc->uc_mcontext.gregs[EDX],

            uc->uc_mcontext.gregs[ESI],

            uc->uc_mcontext.gregs[EDI],

            uc->uc_mcontext.gregs[EBP],

            uc->uc_mcontext.gregs[ESP],

            uc->uc_mcontext.gregs[EFL],

            uc->uc_mcontext.gregs[EIP]);

}

#else

static void dump_regs(struct ucontext *uc)

{

}

#endif

#endif

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 (cpu_x86_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, "gemu: got signal %d\n", sig);

    dump_regs(puc);

#endif

    host_to_target_siginfo_noswap(&tinfo, info);

    if (queue_signal(sig, &tinfo) == 1) {

        /* interrupt the virtual CPU as soon as possible */

        cpu_x86_interrupt(global_env);

    }

}

int do_sigaction(int sig, const struct target_sigaction *act,

                 struct target_sigaction *oact)

{

    struct emulated_sigaction *k;

    if (sig < 1 || sig > TARGET_NSIG)

        return -EINVAL;

    k = &sigact_table[sig - 1];

#if defined(DEBUG_SIGNAL) && 0

    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);

        oact->sa_restorer = tswapl(k->sa.sa_restorer);

        oact->sa_mask = k->sa.sa_mask;

    }

    if (act) {

        k->sa._sa_handler = tswapl(act->_sa_handler);

        k->sa.sa_flags = tswapl(act->sa_flags);

        k->sa.sa_restorer = tswapl(act->sa_restorer);

        k->sa.sa_mask = act->sa_mask;

    }

    return 0;

}

#ifdef TARGET_I386

/* from the Linux kernel */

struct target_fpreg {

        uint16_t significand[4];

        uint16_t exponent;

};

struct target_fpxreg {

        uint16_t significand[4];

        uint16_t exponent;

        uint16_t padding[3];

};

struct target_xmmreg {

        target_ulong element[4];

};

struct target_fpstate {

        /* Regular FPU environment */

        target_ulong         cw;

        target_ulong        sw;

        target_ulong        tag;

        target_ulong        ipoff;

        target_ulong        cssel;

        target_ulong        dataoff;

        target_ulong        datasel;

        struct target_fpreg        _st[8];

        uint16_t        status;

        uint16_t        magic;                /* 0xffff = regular FPU data only */

        /* FXSR FPU environment */

        target_ulong        _fxsr_env[6];        /* FXSR FPU env is ignored */

        target_ulong        mxcsr;

        target_ulong        reserved;

        struct target_fpxreg        _fxsr_st[8];        /* FXSR FPU reg data is ignored */

        struct target_xmmreg        _xmm[8];

        target_ulong        padding[56];

};

#define X86_FXSR_MAGIC                0x0000

struct target_sigcontext {

        uint16_t gs, __gsh;

        uint16_t fs, __fsh;

        uint16_t es, __esh;

        uint16_t ds, __dsh;

        target_ulong edi;

        target_ulong esi;

        target_ulong ebp;

        target_ulong esp;

        target_ulong ebx;

        target_ulong edx;

        target_ulong ecx;

        target_ulong eax;

        target_ulong trapno;

        target_ulong err;

        target_ulong eip;

        uint16_t cs, __csh;

        target_ulong eflags;

        target_ulong esp_at_signal;

        uint16_t ss, __ssh;

        target_ulong fpstate; /* pointer */

        target_ulong oldmask;

        target_ulong cr2;

};

typedef struct target_sigaltstack {

        target_ulong ss_sp;

        int ss_flags;

        target_ulong ss_size;

} target_stack_t;

struct target_ucontext {

        target_ulong          uc_flags;

        target_ulong      uc_link;

        target_stack_t          uc_stack;

        struct target_sigcontext uc_mcontext;

        target_sigset_t          uc_sigmask;        /* mask last for extensibility */

};

struct sigframe

{

    target_ulong pretcode;

    int sig;

    struct target_sigcontext sc;

    struct target_fpstate fpstate;

    target_ulong extramask[TARGET_NSIG_WORDS-1];

    char retcode[8];

};

struct rt_sigframe

{

    target_ulong pretcode;

    int sig;

    target_ulong pinfo;

    target_ulong puc;

    struct target_siginfo info;

    struct target_ucontext uc;

    struct target_fpstate fpstate;

    char retcode[8];

};

/*

 * Set up a signal frame.

 */

#define __put_user(x,ptr)\

({\

    int size = sizeof(*ptr);\

    switch(size) {\

    case 1:\

        stb(ptr, (typeof(*ptr))(x));\

        break;\

    case 2:\

        stw(ptr, (typeof(*ptr))(x));\

        break;\

    case 4:\

        stl(ptr, (typeof(*ptr))(x));\

        break;\

    case 8:\

        stq(ptr, (typeof(*ptr))(x));\

        break;\

    default:\

        abort();\

    }\

    0;\

})

#define get_user(val, ptr) (typeof(*ptr))(*(ptr))

#define __copy_to_user(dst, src, size)\

({\

    memcpy(dst, src, size);\

    0;\

})

static inline int copy_siginfo_to_user(target_siginfo_t *tinfo, 

                                       const target_siginfo_t *info)

{

    tswap_siginfo(tinfo, info);

    return 0;

}

/* XXX: save x87 state */

static int

setup_sigcontext(struct target_sigcontext *sc, struct target_fpstate *fpstate,

                 CPUX86State *env, unsigned long mask)

{

        int err = 0;

        err |= __put_user(env->segs[R_GS], (unsigned int *)&sc->gs);

        err |= __put_user(env->segs[R_FS], (unsigned int *)&sc->fs);

        err |= __put_user(env->segs[R_ES], (unsigned int *)&sc->es);

        err |= __put_user(env->segs[R_DS], (unsigned int *)&sc->ds);

        err |= __put_user(env->regs[R_EDI], &sc->edi);

        err |= __put_user(env->regs[R_ESI], &sc->esi);

        err |= __put_user(env->regs[R_EBP], &sc->ebp);

        err |= __put_user(env->regs[R_ESP], &sc->esp);

        err |= __put_user(env->regs[R_EBX], &sc->ebx);

        err |= __put_user(env->regs[R_EDX], &sc->edx);

        err |= __put_user(env->regs[R_ECX], &sc->ecx);

        err |= __put_user(env->regs[R_EAX], &sc->eax);

        err |= __put_user(/*current->thread.trap_no*/ 0, &sc->trapno);

        err |= __put_user(/*current->thread.error_code*/ 0, &sc->err);

        err |= __put_user(env->eip, &sc->eip);

        err |= __put_user(env->segs[R_CS], (unsigned int *)&sc->cs);

        err |= __put_user(env->eflags, &sc->eflags);

        err |= __put_user(env->regs[R_ESP], &sc->esp_at_signal);

        err |= __put_user(env->segs[R_SS], (unsigned int *)&sc->ss);

#if 0

        tmp = save_i387(fpstate);

        if (tmp < 0)

          err = 1;

        else

          err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);

#else

        err |= __put_user(0, &sc->fpstate);

#endif

        /* non-iBCS2 extensions.. */

        err |= __put_user(mask, &sc->oldmask);

        err |= __put_user(/*current->thread.cr2*/ 0, &sc->cr2);

        return err;

}

/*

 * Determine which stack to use..

 */

static inline void *

get_sigframe(struct emulated_sigaction *ka, CPUX86State *env, size_t frame_size)

{

        unsigned long esp;

        /* Default to using normal stack */

        esp = env->regs[R_ESP];

#if 0

        /* This is the X/Open sanctioned signal stack switching.  */

        if (ka->sa.sa_flags & SA_ONSTACK) {

                if (sas_ss_flags(esp) == 0)

                        esp = current->sas_ss_sp + current->sas_ss_size;

        }

        /* This is the legacy signal stack switching. */

        else if ((regs->xss & 0xffff) != __USER_DS &&

                 !(ka->sa.sa_flags & SA_RESTORER) &&

                 ka->sa.sa_restorer) {

                esp = (unsigned long) ka->sa.sa_restorer;

        }

#endif

        return (void *)((esp - frame_size) & -8ul);

}

#define TF_MASK TRAP_FLAG

static void setup_frame(int sig, struct emulated_sigaction *ka,

                        target_sigset_t *set, CPUX86State *env)

{

        struct sigframe *frame;

        int err = 0;

        frame = get_sigframe(ka, env, sizeof(*frame));

#if 0

        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))

                goto give_sigsegv;

#endif

        err |= __put_user((/*current->exec_domain

                           && current->exec_domain->signal_invmap

                           && sig < 32

                           ? current->exec_domain->signal_invmap[sig]

                           : */ sig),

                          &frame->sig);

        if (err)

                goto give_sigsegv;

        setup_sigcontext(&frame->sc, &frame->fpstate, env, set->sig[0]);

        if (err)

                goto give_sigsegv;

        if (TARGET_NSIG_WORDS > 1) {

                err |= __copy_to_user(frame->extramask, &set->sig[1],

                                      sizeof(frame->extramask));

        }

        if (err)

                goto give_sigsegv;

        /* Set up to return from userspace.  If provided, use a stub

           already in userspace.  */

        if (ka->sa.sa_flags & TARGET_SA_RESTORER) {

                err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);

        } else {

                err |= __put_user(frame->retcode, &frame->pretcode);

                /* This is popl %eax ; movl $,%eax ; int $0x80 */

                err |= __put_user(0xb858, (short *)(frame->retcode+0));

                err |= __put_user(TARGET_NR_sigreturn, (int *)(frame->retcode+2));

                err |= __put_user(0x80cd, (short *)(frame->retcode+6));

        }

        if (err)

                goto give_sigsegv;

        /* Set up registers for signal handler */

        env->regs[R_ESP] = (unsigned long) frame;

        env->eip = (unsigned long) ka->sa._sa_handler;

        cpu_x86_load_seg(env, R_DS, __USER_DS);

        cpu_x86_load_seg(env, R_ES, __USER_DS);

        cpu_x86_load_seg(env, R_SS, __USER_DS);

        cpu_x86_load_seg(env, R_CS, __USER_CS);

        env->eflags &= ~TF_MASK;

        return;

give_sigsegv:

        if (sig == TARGET_SIGSEGV)

                ka->sa._sa_handler = TARGET_SIG_DFL;

        force_sig(TARGET_SIGSEGV /* , current */);

}

static void setup_rt_frame(int sig, struct emulated_sigaction *ka, 

                           target_siginfo_t *info,

                           target_sigset_t *set, CPUX86State *env)

{

        struct rt_sigframe *frame;

        int err = 0;

        frame = get_sigframe(ka, env, sizeof(*frame));

#if 0

        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))

                goto give_sigsegv;

#endif

        err |= __put_user((/*current->exec_domain

                               && current->exec_domain->signal_invmap

                               && sig < 32

                               ? current->exec_domain->signal_invmap[sig]

                           : */sig),

                          &frame->sig);

        err |= __put_user((target_ulong)&frame->info, &frame->pinfo);

        err |= __put_user((target_ulong)&frame->uc, &frame->puc);

        err |= copy_siginfo_to_user(&frame->info, info);

        if (err)

                goto give_sigsegv;

        /* Create the ucontext.  */

        err |= __put_user(0, &frame->uc.uc_flags);

        err |= __put_user(0, &frame->uc.uc_link);

        err |= __put_user(/*current->sas_ss_sp*/ 0, &frame->uc.uc_stack.ss_sp);

        err |= __put_user(/* sas_ss_flags(regs->esp) */ 0,

                          &frame->uc.uc_stack.ss_flags);

        err |= __put_user(/* current->sas_ss_size */ 0, &frame->uc.uc_stack.ss_size);

        err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,

                                env, set->sig[0]);

        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

        if (err)

                goto give_sigsegv;

        /* Set up to return from userspace.  If provided, use a stub

           already in userspace.  */

        if (ka->sa.sa_flags & TARGET_SA_RESTORER) {

                err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);

        } else {

                err |= __put_user(frame->retcode, &frame->pretcode);

                /* This is movl $,%eax ; int $0x80 */

                err |= __put_user(0xb8, (char *)(frame->retcode+0));

                err |= __put_user(TARGET_NR_rt_sigreturn, (int *)(frame->retcode+1));

                err |= __put_user(0x80cd, (short *)(frame->retcode+5));

        }

        if (err)

                goto give_sigsegv;

        /* Set up registers for signal handler */

        env->regs[R_ESP] = (unsigned long) frame;

        env->eip = (unsigned long) ka->sa._sa_handler;

        cpu_x86_load_seg(env, R_DS, __USER_DS);

        cpu_x86_load_seg(env, R_ES, __USER_DS);

        cpu_x86_load_seg(env, R_SS, __USER_DS);

        cpu_x86_load_seg(env, R_CS, __USER_CS);

        env->eflags &= ~TF_MASK;

        return;

give_sigsegv:

        if (sig == TARGET_SIGSEGV)

                ka->sa._sa_handler = TARGET_SIG_DFL;

        force_sig(TARGET_SIGSEGV /* , current */);

}

static int

restore_sigcontext(CPUX86State *env, struct target_sigcontext *sc, int *peax)

{

        unsigned int err = 0;

#define COPY(x)                err |= __get_user(regs->x, &sc->x)

#define COPY_SEG(seg)                                                        \

        { unsigned short tmp;                                                \

          err |= __get_user(tmp, &sc->seg);                                \

          regs->x##seg = tmp; }

#define COPY_SEG_STRICT(seg)                                                \

        { unsigned short tmp;                                                \

          err |= __get_user(tmp, &sc->seg);                                \

          regs->x##seg = tmp|3; }

#define GET_SEG(seg)                                                        \

        { unsigned short tmp;                                                \

          err |= __get_user(tmp, &sc->seg);                                \

          loadsegment(seg,tmp); }

        cpu_x86_load_seg(env, R_GS, lduw(&sc->gs));

        cpu_x86_load_seg(env, R_FS, lduw(&sc->fs));

        cpu_x86_load_seg(env, R_ES, lduw(&sc->es));

        cpu_x86_load_seg(env, R_DS, lduw(&sc->ds));

        env->regs[R_EDI] = ldl(&sc->edi);

        env->regs[R_ESI] = ldl(&sc->esi);

        env->regs[R_EBP] = ldl(&sc->ebp);

        env->regs[R_ESP] = ldl(&sc->esp);

        env->regs[R_EBX] = ldl(&sc->ebx);

        env->regs[R_EDX] = ldl(&sc->edx);

        env->regs[R_ECX] = ldl(&sc->ecx);

        env->eip = ldl(&sc->eip);

        cpu_x86_load_seg(env, R_CS, lduw(&sc->cs) | 3);

        cpu_x86_load_seg(env, R_SS, lduw(&sc->ss) | 3);

        {

                unsigned int tmpflags;

                tmpflags = ldl(&sc->eflags);

                env->eflags = (env->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);

                //                regs->orig_eax = -1;                /* disable syscall checks */

        }

#if 0

        {

                struct _fpstate * buf;

                err |= __get_user(buf, &sc->fpstate);

                if (buf) {

                        if (verify_area(VERIFY_READ, buf, sizeof(*buf)))

                                goto badframe;

                        err |= restore_i387(buf);

                }

        }

#endif

        *peax = ldl(&sc->eax);

        return err;

#if 0

badframe:

        return 1;

#endif

}

long do_sigreturn(CPUX86State *env)

{

    struct sigframe *frame = (struct sigframe *)(env->regs[R_ESP] - 8);

    target_sigset_t target_set;

    sigset_t set;

    int eax, i;

    /* set blocked signals */

    target_set.sig[0] = frame->sc.oldmask;

    for(i = 1; i < TARGET_NSIG_WORDS; i++)

        target_set.sig[i] = frame->extramask[i - 1];

    target_to_host_sigset(&set, &target_set);

    sigprocmask(SIG_SETMASK, &set, NULL);

    /* restore registers */

    if (restore_sigcontext(env, &frame->sc, &eax))

        goto badframe;

    return eax;

badframe:

    force_sig(TARGET_SIGSEGV);

    return 0;

}

long do_rt_sigreturn(CPUX86State *env)

{

        struct rt_sigframe *frame = (struct rt_sigframe *)(env->regs[R_ESP] - 4);

        target_sigset_t target_set;

        sigset_t set;

        //        stack_t st;

        int eax;

#if 0

        if (verify_area(VERIFY_READ, frame, sizeof(*frame)))

                goto badframe;

#endif

        memcpy(&target_set, &frame->uc.uc_sigmask, sizeof(target_sigset_t));

        target_to_host_sigset(&set, &target_set);

        sigprocmask(SIG_SETMASK, &set, NULL);

        if (restore_sigcontext(env, &frame->uc.uc_mcontext, &eax))

                goto badframe;

#if 0

        if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))

                goto badframe;

        /* It is more difficult to avoid calling this function than to

           call it and ignore errors.  */

        do_sigaltstack(&st, NULL, regs->esp);

#endif

        return eax;

badframe:

        force_sig(TARGET_SIGSEGV);

        return 0;

}

#endif

void process_pending_signals(void *cpu_env)

{

    int sig;

    target_ulong handler;

    sigset_t set, old_set;

    target_sigset_t target_old_set;

    struct emulated_sigaction *k;

    struct sigqueue *q;

    if (!signal_pending)

        return;

    k = sigact_table;

    for(sig = 1; sig <= TARGET_NSIG; sig++) {

        if (k->pending)

            goto handle_signal;

        k++;

    }

    /* if no signal is pending, just return */

    signal_pending = 0;

    return;

 handle_signal:

#ifdef DEBUG_SIGNAL

    fprintf(stderr, "gemu: process signal %d\n", sig);

#endif

    /* dequeue signal */

    q = k->first;

    k->first = q->next;

    if (!k->first)

        k->pending = 0;

    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 if (handler == TARGET_SIG_IGN) {

        /* ignore sig */

    } else if (handler == TARGET_SIG_ERR) {

        force_sig(sig);

    } else {

        /* compute the blocked signals during the handler execution */

        target_to_host_sigset(&set, &k->sa.sa_mask);

        /* SA_NODEFER indicates that the current signal should not be

           blocked during the handler */

        if (!(k->sa.sa_flags & TARGET_SA_NODEFER))

            sigaddset(&set, target_to_host_signal(sig));

        /* block signals in the handler using Linux */

        sigprocmask(SIG_BLOCK, &set, &old_set);

        /* save the previous blocked signal state to restore it at the

           end of the signal execution (see do_sigreturn) */

        host_to_target_sigset(&target_old_set, &old_set);

        /* prepare the stack frame of the virtual CPU */

        if (k->sa.sa_flags & TARGET_SA_SIGINFO)

            setup_rt_frame(sig, k, &q->info, &target_old_set, cpu_env);

        else

            setup_frame(sig, k, &target_old_set, cpu_env);

        if (k->sa.sa_flags & TARGET_SA_RESETHAND)

            k->sa._sa_handler = TARGET_SIG_DFL;