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 <unistd.h>

#include <signal.h>

#include <errno.h>

#include <sys/ucontext.h>

#ifdef __ia64__

#undef uc_mcontext

#undef uc_sigmask

#undef uc_stack

#undef uc_link

#endif

#include <signal.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 */

};

struct sigaltstack target_sigaltstack_used = {

    0, 0, SA_DISABLE

};

static struct emulated_sigaction sigact_table[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 inline int host_to_target_signal(int sig)

{

    return sig;

}

static inline int target_to_host_signal(int sig)

{

    return sig;

}

/* siginfo conversion */

void host_to_target_siginfo(target_siginfo_t *tinfo, const siginfo_t *info)

{

}

void target_to_host_siginfo(siginfo_t *info, const target_siginfo_t *tinfo)

{

}

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, "qemu: uncaught target signal %d (%s) - exiting\n",

            sig, strsignal(host_sig));

    _exit(-host_sig);

}

/* 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 = (target_ulong)k->sa.sa_handler;

    if (handler == SIG_DFL) {

        /* default handler : ignore some signal. The other are fatal */

        if (sig != SIGCHLD &&

            sig != SIGURG &&

            sig != SIGWINCH) {

            force_sig(sig);

        } else {

            return 0; /* indicate ignored */

        }

    } else if (handler == host_to_target_signal(SIG_IGN)) {

        /* ignore signal */

        return 0;

    } else if (handler == host_to_target_signal(SIG_ERR)) {

        force_sig(sig);

    } else {

        pq = &k->first;

        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 (cpu_signal_handler(host_signum, (void*)info, puc))

            return;

    }

    /* get target signal number */

    sig = host_to_target_signal(host_signum);

    if (sig < 1 || sig > NSIG)

        return;

#if defined(DEBUG_SIGNAL)

        fprintf(stderr, "qemu: got signal %d\n", sig);

#endif

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

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

        cpu_interrupt(global_env, CPU_INTERRUPT_EXIT);

    }

}

int do_sigaltstack(const struct sigaltstack *ss, struct sigaltstack *oss)

{

    /* XXX: test errors */

    if(oss)

    {

        oss->ss_sp = tswap32(target_sigaltstack_used.ss_sp);

        oss->ss_size = tswap32(target_sigaltstack_used.ss_size);

        oss->ss_flags = tswap32(target_sigaltstack_used.ss_flags);

    }

    if(ss)

    {

        target_sigaltstack_used.ss_sp = tswap32(ss->ss_sp);

        target_sigaltstack_used.ss_size = tswap32(ss->ss_size);

        target_sigaltstack_used.ss_flags = tswap32(ss->ss_flags);

    }

    return 0;

}

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

                 struct sigaction *oact)

{

    struct emulated_sigaction *k;

    struct sigaction act1;

    int host_sig;

    if (sig < 1 || sig > NSIG)

        return -EINVAL;

    k = &sigact_table[sig - 1];

#if defined(DEBUG_SIGNAL)

    fprintf(stderr, "sigaction 1 sig=%d act=0x%08x, oact=0x%08x\n",

            sig, (int)act, (int)oact);

#endif

    if (oact) {

#if defined(DEBUG_SIGNAL)

    fprintf(stderr, "sigaction 1 sig=%d act=0x%08x, oact=0x%08x\n",

            sig, (int)act, (int)oact);

#endif

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

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

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

    }

    if (act) {

#if defined(DEBUG_SIGNAL)

    fprintf(stderr, "sigaction handler 0x%x flag 0x%x mask 0x%x\n",

            act->sa_handler, act->sa_flags, act->sa_mask);

#endif

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

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

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

        /* we update the host signal state */

        host_sig = target_to_host_signal(sig);

        if (host_sig != SIGSEGV && host_sig != SIGBUS) {

#if defined(DEBUG_SIGNAL)

    fprintf(stderr, "sigaction handler going to call sigaction\n",

            act->sa_handler, act->sa_flags, act->sa_mask);

#endif

            sigfillset(&act1.sa_mask);

            act1.sa_flags = SA_SIGINFO;

            if (k->sa.sa_flags & SA_RESTART)

                act1.sa_flags |= SA_RESTART;

            /* NOTE: it is important to update the host kernel signal

               ignore state to avoid getting unexpected interrupted

               syscalls */

            if (k->sa.sa_handler == SIG_IGN) {

                act1.sa_sigaction = (void *)SIG_IGN;

            } else if (k->sa.sa_handler == SIG_DFL) {

                act1.sa_sigaction = (void *)SIG_DFL;

            } else {

                act1.sa_sigaction = host_signal_handler;

            }

            sigaction(host_sig, &act1, NULL);

        }

    }

    return 0;

}

#ifdef TARGET_I386

static inline void *

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

{

    /* XXX Fix that */

    if(target_sigaltstack_used.ss_flags & SA_DISABLE)

    {

        int esp;

        /* Default to using normal stack */

        esp = env->regs[R_ESP];

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

    }

    else

    {

        return target_sigaltstack_used.ss_sp;

    }

}

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

                        void *set, CPUState *env)

{

        void *frame;

        int i, err = 0;

    fprintf(stderr, "setup_frame %d\n", sig);

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

        /* Set up registers for signal handler */

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

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

        env->eflags &= ~TF_MASK;

        return;

give_sigsegv:

        if (sig == SIGSEGV)

                ka->sa.sa_handler = SIG_DFL;

        force_sig(SIGSEGV /* , current */);

}

long do_sigreturn(CPUState *env, int num)

{

    int i = 0;

    struct target_sigcontext *scp = get_int_arg(&i, env);

    /* XXX Get current signal number */

    /* XXX Adjust accordin to sc_onstack, sc_mask */

    if(tswapl(scp->sc_onstack) & 0x1)

        target_sigaltstack_used.ss_flags |= ~SA_DISABLE;

    else

        target_sigaltstack_used.ss_flags &=  SA_DISABLE;

    int set = tswapl(scp->sc_eax);

    sigprocmask(SIG_SETMASK, &set, NULL);

    fprintf(stderr, "do_sigreturn: partially implemented %x EAX:%x EBX:%x\n", scp->sc_mask, tswapl(scp->sc_eax), tswapl(scp->sc_ebx));

    fprintf(stderr, "ECX:%x EDX:%x EDI:%x\n", scp->sc_ecx, tswapl(scp->sc_edx), tswapl(scp->sc_edi));

    fprintf(stderr, "EIP:%x\n", tswapl(scp->sc_eip));

    env->regs[R_EAX] = tswapl(scp->sc_eax);

    env->regs[R_EBX] = tswapl(scp->sc_ebx);

    env->regs[R_ECX] = tswapl(scp->sc_ecx);

    env->regs[R_EDX] = tswapl(scp->sc_edx);

    env->regs[R_EDI] = tswapl(scp->sc_edi);

    env->regs[R_ESI] = tswapl(scp->sc_esi);

    env->regs[R_EBP] = tswapl(scp->sc_ebp);

    env->regs[R_ESP] = tswapl(scp->sc_esp);

    env->segs[R_SS].selector = (void*)tswapl(scp->sc_ss);

    env->eflags = tswapl(scp->sc_eflags);

    env->eip = tswapl(scp->sc_eip);

    env->segs[R_CS].selector = (void*)tswapl(scp->sc_cs);

    env->segs[R_DS].selector = (void*)tswapl(scp->sc_ds);

    env->segs[R_ES].selector = (void*)tswapl(scp->sc_es);

    env->segs[R_FS].selector = (void*)tswapl(scp->sc_fs);

    env->segs[R_GS].selector = (void*)tswapl(scp->sc_gs);

    /* Again, because our caller's caller will reset EAX */

    return env->regs[R_EAX];

}

#else

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

                        void *set, CPUState *env)

{

    fprintf(stderr, "setup_frame: not implemented\n");

}

long do_sigreturn(CPUState *env, int num)

{

    int i = 0;

    struct target_sigcontext *scp = get_int_arg(&i, env);

    fprintf(stderr, "do_sigreturn: not implemented\n");

    return -ENOSYS;

}

#endif

void process_pending_signals(void *cpu_env)

{

    struct emulated_sigaction *k;

    struct sigqueue *q;

    target_ulong handler;

    int sig;

    if (!signal_pending)

        return;

    k = sigact_table;

    for(sig = 1; sig <= 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, "qemu: process signal %d\n", sig);

    #endif

    /* dequeue signal */

    q = k->first;

    k->first = q->next;

    if (!k->first)

        k->pending = 0;

    sig = gdb_handlesig (cpu_env, sig);

    if (!sig) {

        fprintf (stderr, "Lost signal\n");

        abort();

    }

    handler = k->sa.sa_handler;

    if (handler == SIG_DFL) {

        /* default handler : ignore some signal. The other are fatal */

        if (sig != SIGCHLD &&

            sig != SIGURG &&

            sig != SIGWINCH) {

            force_sig(sig);

        }

    } else if (handler == SIG_IGN) {

        /* ignore sig */

    } else if (handler == SIG_ERR) {

        force_sig(sig);

    } else {

        setup_frame(sig, k, 0, cpu_env);

        if (k->sa.sa_flags & SA_RESETHAND)

            k->sa.sa_handler = SIG_DFL;

    }

    if (q != &k->info)

        free_sigqueue(q);

}