signal.c

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        target_ulong fpu_save;
        int err, i;

        sf = (struct target_signal_frame *)g2h(env->regwptr[UREG_FP]);
#if 0
	fprintf(stderr, "sigreturn\n");
	fprintf(stderr, "sf: %x pc %x fp %x sp %x\n", sf, env->pc, env->regwptr[UREG_FP], env->regwptr[UREG_SP]);
#endif
	//cpu_dump_state(env, stderr, fprintf, 0);

        /* 1. Make sure we are not getting garbage from the user */
#if 0
        if (verify_area (VERIFY_READ, sf, sizeof (*sf)))
                goto segv_and_exit;
#endif

        if (((uint) sf) & 3)
                goto segv_and_exit;

        err = __get_user(pc,  &sf->info.si_regs.pc);
        err |= __get_user(npc, &sf->info.si_regs.npc);

        if ((pc | npc) & 3)
                goto segv_and_exit;

        /* 2. Restore the state */
        err |= __get_user(up_psr, &sf->info.si_regs.psr);

        /* User can only change condition codes and FPU enabling in %psr. */
        env->psr = (up_psr & (PSR_ICC /* | PSR_EF */))
                  | (env->psr & ~(PSR_ICC /* | PSR_EF */));

	env->pc = pc;
	env->npc = npc;
        err |= __get_user(env->y, &sf->info.si_regs.y);
	for (i=0; i < 8; i++) {
		err |= __get_user(env->gregs[i], &sf->info.si_regs.u_regs[i]);
	}
	for (i=0; i < 8; i++) {
		err |= __get_user(env->regwptr[i + UREG_I0], &sf->info.si_regs.u_regs[i+8]);
	}

        err |= __get_user(fpu_save, (target_ulong *)&sf->fpu_save);

        //if (fpu_save)
        //        err |= restore_fpu_state(env, fpu_save);

        /* This is pretty much atomic, no amount locking would prevent
         * the races which exist anyways.
         */
        err |= __get_user(set.sig[0], &sf->info.si_mask);
        for(i = 1; i < TARGET_NSIG_WORDS; i++) {
            err |= (__get_user(set.sig[i], &sf->extramask[i - 1]));
        }

        target_to_host_sigset_internal(&host_set, &set);
        sigprocmask(SIG_SETMASK, &host_set, NULL);

        if (err)
                goto segv_and_exit;

        return env->regwptr[0];

segv_and_exit:
	force_sig(TARGET_SIGSEGV);
}

long do_rt_sigreturn(CPUState *env)
{
    fprintf(stderr, "do_rt_sigreturn: not implemented\n");
    return -ENOSYS;
}

#elif defined(TARGET_MIPS)

struct target_sigcontext {
    uint32_t   sc_regmask;     /* Unused */
    uint32_t   sc_status;
    uint64_t   sc_pc;
    uint64_t   sc_regs[32];
    uint64_t   sc_fpregs[32];
    uint32_t   sc_ownedfp;     /* Unused */
    uint32_t   sc_fpc_csr;
    uint32_t   sc_fpc_eir;     /* Unused */
    uint32_t   sc_used_math;
    uint32_t   sc_dsp;         /* dsp status, was sc_ssflags */
    uint64_t   sc_mdhi;
    uint64_t   sc_mdlo;
    target_ulong   sc_hi1;         /* Was sc_cause */
    target_ulong   sc_lo1;         /* Was sc_badvaddr */
    target_ulong   sc_hi2;         /* Was sc_sigset[4] */
    target_ulong   sc_lo2;
    target_ulong   sc_hi3;
    target_ulong   sc_lo3;
};

struct sigframe {
    uint32_t sf_ass[4];			/* argument save space for o32 */
    uint32_t sf_code[2];			/* signal trampoline */
    struct target_sigcontext sf_sc;
    target_sigset_t sf_mask;
};

/* Install trampoline to jump back from signal handler */
static inline int install_sigtramp(unsigned int *tramp,   unsigned int syscall)
{
    int err;

    /*
    * Set up the return code ...
    *
    *         li      v0, __NR__foo_sigreturn
    *         syscall
    */

    err = __put_user(0x24020000 + syscall, tramp + 0);
    err |= __put_user(0x0000000c          , tramp + 1);
    /* flush_cache_sigtramp((unsigned long) tramp); */
    return err;
}

static inline int
setup_sigcontext(CPUState *regs, struct target_sigcontext *sc)
{
    int err = 0;

    err |= __put_user(regs->PC, &sc->sc_pc);

    #define save_gp_reg(i) do {   					\
        err |= __put_user(regs->gpr[i], &sc->sc_regs[i]);		\
    } while(0)
    __put_user(0, &sc->sc_regs[0]); save_gp_reg(1); save_gp_reg(2);
    save_gp_reg(3); save_gp_reg(4); save_gp_reg(5); save_gp_reg(6);
    save_gp_reg(7); save_gp_reg(8); save_gp_reg(9); save_gp_reg(10);
    save_gp_reg(11); save_gp_reg(12); save_gp_reg(13); save_gp_reg(14);
    save_gp_reg(15); save_gp_reg(16); save_gp_reg(17); save_gp_reg(18);
    save_gp_reg(19); save_gp_reg(20); save_gp_reg(21); save_gp_reg(22);
    save_gp_reg(23); save_gp_reg(24); save_gp_reg(25); save_gp_reg(26);
    save_gp_reg(27); save_gp_reg(28); save_gp_reg(29); save_gp_reg(30);
    save_gp_reg(31);
    #undef save_gp_reg

    err |= __put_user(regs->HI, &sc->sc_mdhi);
    err |= __put_user(regs->LO, &sc->sc_mdlo);

    /* Not used yet, but might be useful if we ever have DSP suppport */
#if 0
    if (cpu_has_dsp) {
	err |= __put_user(mfhi1(), &sc->sc_hi1);
	err |= __put_user(mflo1(), &sc->sc_lo1);
	err |= __put_user(mfhi2(), &sc->sc_hi2);
	err |= __put_user(mflo2(), &sc->sc_lo2);
	err |= __put_user(mfhi3(), &sc->sc_hi3);
	err |= __put_user(mflo3(), &sc->sc_lo3);
	err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
    }
    /* same with 64 bit */
    #ifdef CONFIG_64BIT
    err |= __put_user(regs->hi, &sc->sc_hi[0]);
    err |= __put_user(regs->lo, &sc->sc_lo[0]);
    if (cpu_has_dsp) {
	err |= __put_user(mfhi1(), &sc->sc_hi[1]);
	err |= __put_user(mflo1(), &sc->sc_lo[1]);
	err |= __put_user(mfhi2(), &sc->sc_hi[2]);
	err |= __put_user(mflo2(), &sc->sc_lo[2]);
	err |= __put_user(mfhi3(), &sc->sc_hi[3]);
	err |= __put_user(mflo3(), &sc->sc_lo[3]);
	err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
    }
    #endif


    #endif


    #if 0
    err |= __put_user(!!used_math(), &sc->sc_used_math);

    if (!used_math())
	goto out;

    /*
    * Save FPU state to signal context.  Signal handler will "inherit"
    * current FPU state.
    */
    preempt_disable();

    if (!is_fpu_owner()) {
	own_fpu();
	restore_fp(current);
    }
    err |= save_fp_context(sc);

    preempt_enable();
    out:
#endif
    return err;
}

static inline int
restore_sigcontext(CPUState *regs, struct target_sigcontext *sc)
{
    int err = 0;

    err |= __get_user(regs->CP0_EPC, &sc->sc_pc);

    err |= __get_user(regs->HI, &sc->sc_mdhi);
    err |= __get_user(regs->LO, &sc->sc_mdlo);

    #define restore_gp_reg(i) do {   					\
        err |= __get_user(regs->gpr[i], &sc->sc_regs[i]);		\
    } while(0)
    restore_gp_reg( 1); restore_gp_reg( 2); restore_gp_reg( 3);
    restore_gp_reg( 4); restore_gp_reg( 5); restore_gp_reg( 6);
    restore_gp_reg( 7); restore_gp_reg( 8); restore_gp_reg( 9);
    restore_gp_reg(10); restore_gp_reg(11); restore_gp_reg(12);
    restore_gp_reg(13); restore_gp_reg(14); restore_gp_reg(15);
    restore_gp_reg(16); restore_gp_reg(17); restore_gp_reg(18);
    restore_gp_reg(19); restore_gp_reg(20); restore_gp_reg(21);
    restore_gp_reg(22); restore_gp_reg(23); restore_gp_reg(24);
    restore_gp_reg(25); restore_gp_reg(26); restore_gp_reg(27);
    restore_gp_reg(28); restore_gp_reg(29); restore_gp_reg(30);
    restore_gp_reg(31);
    #undef restore_gp_reg

#if 0
    if (cpu_has_dsp) {
	err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
	err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
	err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
	err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
	err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
	err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
	err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
    }
    #ifdef CONFIG_64BIT
    err |= __get_user(regs->hi, &sc->sc_hi[0]);
    err |= __get_user(regs->lo, &sc->sc_lo[0]);
    if (cpu_has_dsp) {
	err |= __get_user(treg, &sc->sc_hi[1]); mthi1(treg);
	err |= __get_user(treg, &sc->sc_lo[1]); mthi1(treg);
	err |= __get_user(treg, &sc->sc_hi[2]); mthi2(treg);
	err |= __get_user(treg, &sc->sc_lo[2]); mthi2(treg);
	err |= __get_user(treg, &sc->sc_hi[3]); mthi3(treg);
	err |= __get_user(treg, &sc->sc_lo[3]); mthi3(treg);
	err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
    }
    #endif

    err |= __get_user(used_math, &sc->sc_used_math);
    conditional_used_math(used_math);

    preempt_disable();

    if (used_math()) {
	/* restore fpu context if we have used it before */
	own_fpu();
	err |= restore_fp_context(sc);
    } else {
	/* signal handler may have used FPU.  Give it up. */
	lose_fpu();
    }

    preempt_enable();
#endif
    return err;
}
/*
 * Determine which stack to use..
 */
static inline void *
get_sigframe(struct emulated_sigaction *ka, CPUState *regs, size_t frame_size)
{
    unsigned long sp;

    /* Default to using normal stack */
    sp = regs->gpr[29];

    /*
     * FPU emulator may have it's own trampoline active just
     * above the user stack, 16-bytes before the next lowest
     * 16 byte boundary.  Try to avoid trashing it.
     */
    sp -= 32;

#if 0
    /* This is the X/Open sanctioned signal stack switching.  */
    if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags (sp) == 0))
	sp = current->sas_ss_sp + current->sas_ss_size;
#endif

    return g2h((sp - frame_size) & ~7);
}

static void setup_frame(int sig, struct emulated_sigaction * ka, 
   		target_sigset_t *set, CPUState *regs)
{
    struct sigframe *frame;
    int i;

    frame = get_sigframe(ka, regs, sizeof(*frame));
    if (!access_ok(VERIFY_WRITE, frame, sizeof (*frame)))
	goto give_sigsegv;

    install_sigtramp(frame->sf_code, TARGET_NR_sigreturn);

    if(setup_sigcontext(regs, &frame->sf_sc))
	goto give_sigsegv;

    for(i = 0; i < TARGET_NSIG_WORDS; i++) {
	if(__put_user(set->sig[i], &frame->sf_mask.sig[i]))
	    goto give_sigsegv;
    }

    /*
    * Arguments to signal handler:
    *
    *   a0 = signal number
    *   a1 = 0 (should be cause)
    *   a2 = pointer to struct sigcontext
    *
    * $25 and PC point to the signal handler, $29 points to the
    * struct sigframe.
    */
    regs->gpr[ 4] = sig;
    regs->gpr[ 5] = 0;
    regs->gpr[ 6] = h2g(&frame->sf_sc);
    regs->gpr[29] = h2g(frame);
    regs->gpr[31] = h2g(frame->sf_code);
    /* The original kernel code sets CP0_EPC to the handler
    * since it returns to userland using eret
    * we cannot do this here, and we must set PC directly */
    regs->PC = regs->gpr[25] = ka->sa._sa_handler;
    return;

give_sigsegv:
    force_sig(TARGET_SIGSEGV/*, current*/);
    return;	
}

long do_sigreturn(CPUState *regs)
{
   struct sigframe *frame;
   sigset_t blocked;
   target_sigset_t target_set;
   int i;

#if defined(DEBUG_SIGNAL)
   fprintf(stderr, "do_sigreturn\n");
#endif
   frame = (struct sigframe *) regs->gpr[29];
   if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
   	goto badframe;

   for(i = 0; i < TARGET_NSIG_WORDS; i++) {
   	if(__get_user(target_set.sig[i], &frame->sf_mask.sig[i]))
	    goto badframe;
   }		

   target_to_host_sigset_internal(&blocked, &target_set);
   sigprocmask(SIG_SETMASK, &blocked, NULL);

   if (restore_sigcontext(regs, &frame->sf_sc))
   	goto badframe;

#if 0
   /*
    * Don't let your children do this ...
    */
   __asm__ __volatile__(
   	"move\t$29, %0\n\t"
   	"j\tsyscall_exit"
   	:/* no outputs */
   	:"r" (&regs));
   /* Unreached */
#endif
    
    regs->PC = regs->CP0_EPC;
   /* I am not sure this is right, but it seems to work
    * maybe a problem with nested signals ? */
    regs->CP0_EPC = 0;
    return 0;

badframe:
   force_sig(TARGET_SIGSEGV/*, current*/);
   return 0;	

}

static void setup_rt_frame(int sig, struct emulated_sigaction *ka, 
                           target_siginfo_t *info,
			   target_sigset_t *set, CPUState *env)
{
    fprintf(stderr, "setup_rt_frame: not implemented\n");
}

long do_rt_sigreturn(CPUState *env)
{
    fprintf(stderr, "do_rt_sigreturn: not implemented\n");
    return -ENOSYS;
}

#else

static void setup_frame(int sig, struct emulated_sigaction *ka,
			target_sigset_t *set, CPUState *env)
{
    fprintf(stderr, "setup_frame: not implemented\n");
}

static void setup_rt_frame(int sig, struct emulated_sigaction *ka, 
                           target_siginfo_t *info,
			   target_sigset_t *set, CPUState *env)
{
    fprintf(stderr, "setup_rt_frame: not implemented\n");
}

long do_sigreturn(CPUState *env)
{
    fprintf(stderr, "do_sigreturn: not implemented\n");
    return -ENOSYS;
}

long do_rt_sigreturn(CPUState *env)
{
    fprintf(stderr, "do_rt_sigreturn: not implemented\n");
    return -ENOSYS;
}

#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, "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 == 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_internal(&target_old_set, &old_set);

        /* if the CPU is in VM86 mode, we restore the 32 bit values */
#ifdef TARGET_I386
        {
            CPUX86State *env = cpu_env;
            if (env->eflags & VM_MASK)
                save_v86_state(env);
        }
#endif
        /* 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;
    }
    if (q != &k->info)
        free_sigqueue(q);
}