signal.c

底层驱动开发

		goto badframe;
	if (__get_user(set.sig[0], &frame->sc.sc_mask) ||
	    (_NSIG_WORDS > 1 &&
	     __copy_from_user(&set.sig[1], &frame->extramask,
			      sizeof(frame->extramask))))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	current->blocked = set;
	recalc_sigpending();

	if (restore_sigcontext(regs, &frame->sc, frame + 1, &d0))
		goto badframe;
	return d0;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

asmlinkage int do_rt_sigreturn(unsigned long __unused)
{
	struct switch_stack *sw = (struct switch_stack *) &__unused;
	struct pt_regs *regs = (struct pt_regs *) (sw + 1);
	unsigned long usp = rdusp();
	struct rt_sigframe *frame = (struct rt_sigframe *)(usp - 4);
	sigset_t set;
	int d0;

	if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
		goto badframe;
	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
		goto badframe;

	sigdelsetmask(&set, ~_BLOCKABLE);
	current->blocked = set;
	recalc_sigpending();

	if (rt_restore_ucontext(regs, sw, &frame->uc, &d0))
		goto badframe;
	return d0;

badframe:
	force_sig(SIGSEGV, current);
	return 0;
}

/*
 * Set up a signal frame.
 */

static inline void save_fpu_state(struct sigcontext *sc, struct pt_regs *regs)
{
	if (FPU_IS_EMU) {
		/* save registers */
		memcpy(sc->sc_fpcntl, current->thread.fpcntl, 12);
		memcpy(sc->sc_fpregs, current->thread.fp, 24);
		return;
	}

	__asm__ volatile (".chip 68k/68881\n\t"
			  "fsave %0\n\t"
			  ".chip 68k"
			  : : "m" (*sc->sc_fpstate) : "memory");

	if (CPU_IS_060 ? sc->sc_fpstate[2] : sc->sc_fpstate[0]) {
		fpu_version = sc->sc_fpstate[0];
		if (CPU_IS_020_OR_030 &&
		    regs->vector >= (VEC_FPBRUC * 4) &&
		    regs->vector <= (VEC_FPNAN * 4)) {
			/* Clear pending exception in 68882 idle frame */
			if (*(unsigned short *) sc->sc_fpstate == 0x1f38)
				sc->sc_fpstate[0x38] |= 1 << 3;
		}
		__asm__ volatile (".chip 68k/68881\n\t"
				  "fmovemx %%fp0-%%fp1,%0\n\t"
				  "fmoveml %%fpcr/%%fpsr/%%fpiar,%1\n\t"
				  ".chip 68k"
				  : "=m" (*sc->sc_fpregs),
				    "=m" (*sc->sc_fpcntl)
				  : /* no inputs */
				  : "memory");
	}
}

static inline int rt_save_fpu_state(struct ucontext *uc, struct pt_regs *regs)
{
	unsigned char fpstate[FPCONTEXT_SIZE];
	int context_size = CPU_IS_060 ? 8 : 0;
	int err = 0;

	if (FPU_IS_EMU) {
		/* save fpu control register */
		err |= copy_to_user(uc->uc_mcontext.fpregs.f_fpcntl,
				current->thread.fpcntl, 12);
		/* save all other fpu register */
		err |= copy_to_user(uc->uc_mcontext.fpregs.f_fpregs,
				current->thread.fp, 96);
		return err;
	}

	__asm__ volatile (".chip 68k/68881\n\t"
			  "fsave %0\n\t"
			  ".chip 68k"
			  : : "m" (*fpstate) : "memory");

	err |= __put_user(*(long *)fpstate, (long *)&uc->uc_fpstate);
	if (CPU_IS_060 ? fpstate[2] : fpstate[0]) {
		fpregset_t fpregs;
		if (!CPU_IS_060)
			context_size = fpstate[1];
		fpu_version = fpstate[0];
		if (CPU_IS_020_OR_030 &&
		    regs->vector >= (VEC_FPBRUC * 4) &&
		    regs->vector <= (VEC_FPNAN * 4)) {
			/* Clear pending exception in 68882 idle frame */
			if (*(unsigned short *) fpstate == 0x1f38)
				fpstate[0x38] |= 1 << 3;
		}
		__asm__ volatile (".chip 68k/68881\n\t"
				  "fmovemx %%fp0-%%fp7,%0\n\t"
				  "fmoveml %%fpcr/%%fpsr/%%fpiar,%1\n\t"
				  ".chip 68k"
				  : "=m" (*fpregs.f_fpregs),
				    "=m" (*fpregs.f_fpcntl)
				  : /* no inputs */
				  : "memory");
		err |= copy_to_user(&uc->uc_mcontext.fpregs, &fpregs,
				    sizeof(fpregs));
	}
	if (context_size)
		err |= copy_to_user((long *)&uc->uc_fpstate + 1, fpstate + 4,
				    context_size);
	return err;
}

static void setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs,
			     unsigned long mask)
{
	sc->sc_mask = mask;
	sc->sc_usp = rdusp();
	sc->sc_d0 = regs->d0;
	sc->sc_d1 = regs->d1;
	sc->sc_a0 = regs->a0;
	sc->sc_a1 = regs->a1;
	sc->sc_sr = regs->sr;
	sc->sc_pc = regs->pc;
	sc->sc_formatvec = regs->format << 12 | regs->vector;
	save_fpu_state(sc, regs);
}

static inline int rt_setup_ucontext(struct ucontext *uc, struct pt_regs *regs)
{
	struct switch_stack *sw = (struct switch_stack *)regs - 1;
	greg_t *gregs = uc->uc_mcontext.gregs;
	int err = 0;

	err |= __put_user(MCONTEXT_VERSION, &uc->uc_mcontext.version);
	err |= __put_user(regs->d0, &gregs[0]);
	err |= __put_user(regs->d1, &gregs[1]);
	err |= __put_user(regs->d2, &gregs[2]);
	err |= __put_user(regs->d3, &gregs[3]);
	err |= __put_user(regs->d4, &gregs[4]);
	err |= __put_user(regs->d5, &gregs[5]);
	err |= __put_user(sw->d6, &gregs[6]);
	err |= __put_user(sw->d7, &gregs[7]);
	err |= __put_user(regs->a0, &gregs[8]);
	err |= __put_user(regs->a1, &gregs[9]);
	err |= __put_user(regs->a2, &gregs[10]);
	err |= __put_user(sw->a3, &gregs[11]);
	err |= __put_user(sw->a4, &gregs[12]);
	err |= __put_user(sw->a5, &gregs[13]);
	err |= __put_user(sw->a6, &gregs[14]);
	err |= __put_user(rdusp(), &gregs[15]);
	err |= __put_user(regs->pc, &gregs[16]);
	err |= __put_user(regs->sr, &gregs[17]);
	err |= __put_user((regs->format << 12) | regs->vector, &uc->uc_formatvec);
	err |= rt_save_fpu_state(uc, regs);
	return err;
}

static inline void push_cache (unsigned long vaddr)
{
	/*
	 * Using the old cache_push_v() was really a big waste.
	 *
	 * What we are trying to do is to flush 8 bytes to ram.
	 * Flushing 2 cache lines of 16 bytes is much cheaper than
	 * flushing 1 or 2 pages, as previously done in
	 * cache_push_v().
	 *                                                     Jes
	 */
	if (CPU_IS_040) {
		unsigned long temp;

		__asm__ __volatile__ (".chip 68040\n\t"
				      "nop\n\t"
				      "ptestr (%1)\n\t"
				      "movec %%mmusr,%0\n\t"
				      ".chip 68k"
				      : "=r" (temp)
				      : "a" (vaddr));

		temp &= PAGE_MASK;
		temp |= vaddr & ~PAGE_MASK;

		__asm__ __volatile__ (".chip 68040\n\t"
				      "nop\n\t"
				      "cpushl %%bc,(%0)\n\t"
				      ".chip 68k"
				      : : "a" (temp));
	}
	else if (CPU_IS_060) {
		unsigned long temp;
		__asm__ __volatile__ (".chip 68060\n\t"
				      "plpar (%0)\n\t"
				      ".chip 68k"
				      : "=a" (temp)
				      : "0" (vaddr));
		__asm__ __volatile__ (".chip 68060\n\t"
				      "cpushl %%bc,(%0)\n\t"
				      ".chip 68k"
				      : : "a" (temp));
	}
	else {
		/*
		 * 68030/68020 have no writeback cache;
		 * still need to clear icache.
		 * Note that vaddr is guaranteed to be long word aligned.
		 */
		unsigned long temp;
		asm volatile ("movec %%cacr,%0" : "=r" (temp));
		temp += 4;
		asm volatile ("movec %0,%%caar\n\t"
			      "movec %1,%%cacr"
			      : : "r" (vaddr), "r" (temp));
		asm volatile ("movec %0,%%caar\n\t"
			      "movec %1,%%cacr"
			      : : "r" (vaddr + 4), "r" (temp));
	}
}

static inline void *
get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
{
	unsigned long usp;

	/* Default to using normal stack.  */
	usp = rdusp();

	/* This is the X/Open sanctioned signal stack switching.  */
	if (ka->sa.sa_flags & SA_ONSTACK) {
		if (!on_sig_stack(usp))
			usp = current->sas_ss_sp + current->sas_ss_size;
	}
	return (void *)((usp - frame_size) & -8UL);
}

static void setup_frame (int sig, struct k_sigaction *ka,
			 sigset_t *set, struct pt_regs *regs)
{
	struct sigframe *frame;
	int fsize = frame_extra_sizes[regs->format];
	struct sigcontext context;
	int err = 0;

	if (fsize < 0) {
#ifdef DEBUG
		printk ("setup_frame: Unknown frame format %#x\n",
			regs->format);
#endif
		goto give_sigsegv;
	}

	frame = get_sigframe(ka, regs, sizeof(*frame) + fsize);

	if (fsize) {
		err |= copy_to_user (frame + 1, regs + 1, fsize);
		regs->stkadj = fsize;
	}

	err |= __put_user((current_thread_info()->exec_domain
			   && current_thread_info()->exec_domain->signal_invmap
			   && sig < 32
			   ? current_thread_info()->exec_domain->signal_invmap[sig]
			   : sig),
			  &frame->sig);

	err |= __put_user(regs->vector, &frame->code);
	err |= __put_user(&frame->sc, &frame->psc);

	if (_NSIG_WORDS > 1)
		err |= copy_to_user(frame->extramask, &set->sig[1],
				    sizeof(frame->extramask));

	setup_sigcontext(&context, regs, set->sig[0]);
	err |= copy_to_user (&frame->sc, &context, sizeof(context));

	/* Set up to return from userspace.  */
	err |= __put_user(frame->retcode, &frame->pretcode);
	/* moveq #,d0; trap #0 */
	err |= __put_user(0x70004e40 + (__NR_sigreturn << 16),
			  (long *)(frame->retcode));

	if (err)
		goto give_sigsegv;

	push_cache ((unsigned long) &frame->retcode);

	/* Set up registers for signal handler */
	wrusp ((unsigned long) frame);
	regs->pc = (unsigned long) ka->sa.sa_handler;

adjust_stack:
	/* Prepare to skip over the extra stuff in the exception frame.  */
	if (regs->stkadj) {
		struct pt_regs *tregs =
			(struct pt_regs *)((ulong)regs + regs->stkadj);
#ifdef DEBUG
		printk("Performing stackadjust=%04x\n", regs->stkadj);
#endif
		/* This must be copied with decreasing addresses to
                   handle overlaps.  */
		tregs->vector = 0;
		tregs->format = 0;
		tregs->pc = regs->pc;
		tregs->sr = regs->sr;
	}
	return;

give_sigsegv:
	force_sigsegv(sig, current);
	goto adjust_stack;
}

static void setup_rt_frame (int sig, struct k_sigaction *ka, siginfo_t *info,
			    sigset_t *set, struct pt_regs *regs)
{
	struct rt_sigframe *frame;
	int fsize = frame_extra_sizes[regs->format];
	int err = 0;

	if (fsize < 0) {
#ifdef DEBUG
		printk ("setup_frame: Unknown frame format %#x\n",
			regs->format);
#endif
		goto give_sigsegv;
	}

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

	if (fsize) {
		err |= copy_to_user (&frame->uc.uc_extra, regs + 1, fsize);
		regs->stkadj = fsize;
	}

	err |= __put_user((current_thread_info()->exec_domain
			   && current_thread_info()->exec_domain->signal_invmap
			   && sig < 32
			   ? current_thread_info()->exec_domain->signal_invmap[sig]
			   : sig),
			  &frame->sig);
	err |= __put_user(&frame->info, &frame->pinfo);
	err |= __put_user(&frame->uc, &frame->puc);
	err |= copy_siginfo_to_user(&frame->info, info);

	/* Create the ucontext.  */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(0, &frame->uc.uc_link);
	err |= __put_user((void *)current->sas_ss_sp,
			  &frame->uc.uc_stack.ss_sp);
	err |= __put_user(sas_ss_flags(rdusp()),
			  &frame->uc.uc_stack.ss_flags);
	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
	err |= rt_setup_ucontext(&frame->uc, regs);
	err |= copy_to_user (&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Set up to return from userspace.  */
	err |= __put_user(frame->retcode, &frame->pretcode);
	/* moveq #,d0; notb d0; trap #0 */
	err |= __put_user(0x70004600 + ((__NR_rt_sigreturn ^ 0xff) << 16),
			  (long *)(frame->retcode + 0));
	err |= __put_user(0x4e40, (short *)(frame->retcode + 4));

	if (err)
		goto give_sigsegv;

	push_cache ((unsigned long) &frame->retcode);

	/* Set up registers for signal handler */
	wrusp ((unsigned long) frame);
	regs->pc = (unsigned long) ka->sa.sa_handler;

adjust_stack:
	/* Prepare to skip over the extra stuff in the exception frame.  */
	if (regs->stkadj) {
		struct pt_regs *tregs =
			(struct pt_regs *)((ulong)regs + regs->stkadj);
#ifdef DEBUG
		printk("Performing stackadjust=%04x\n", regs->stkadj);
#endif
		/* This must be copied with decreasing addresses to
                   handle overlaps.  */
		tregs->vector = 0;
		tregs->format = 0;
		tregs->pc = regs->pc;
		tregs->sr = regs->sr;
	}
	return;

give_sigsegv:
	force_sigsegv(sig, current);
	goto adjust_stack;
}

static inline void
handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
{
	switch (regs->d0) {
	case -ERESTARTNOHAND:
		if (!has_handler)
			goto do_restart;
		regs->d0 = -EINTR;
		break;

	case -ERESTARTSYS:
		if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
			regs->d0 = -EINTR;
			break;
		}
	/* fallthrough */
	case -ERESTARTNOINTR:
	do_restart:
		regs->d0 = regs->orig_d0;
		regs->pc -= 2;
		break;
	}
}

void ptrace_signal_deliver(struct pt_regs *regs, void *cookie)
{
	if (regs->orig_d0 < 0)
		return;
	switch (regs->d0) {
	case -ERESTARTNOHAND:
	case -ERESTARTSYS:
	case -ERESTARTNOINTR:
		regs->d0 = regs->orig_d0;
		regs->orig_d0 = -1;
		regs->pc -= 2;
		break;
	}
}

/*
 * OK, we're invoking a handler
 */
static void
handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
	      sigset_t *oldset, struct pt_regs *regs)
{
	/* are we from a system call? */
	if (regs->orig_d0 >= 0)
		/* If so, check system call restarting.. */
		handle_restart(regs, ka, 1);

	/* set up the stack frame */
	if (ka->sa.sa_flags & SA_SIGINFO)
		setup_rt_frame(sig, ka, info, oldset, regs);
	else
		setup_frame(sig, ka, oldset, regs);

	if (ka->sa.sa_flags & SA_ONESHOT)
		ka->sa.sa_handler = SIG_DFL;

	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
	if (!(ka->sa.sa_flags & SA_NODEFER))
		sigaddset(&current->blocked,sig);
	recalc_sigpending();
}

/*
 * Note that 'init' is a special process: it doesn't get signals it doesn't
 * want to handle. Thus you cannot kill init even with a SIGKILL even by
 * mistake.
 */
asmlinkage int do_signal(sigset_t *oldset, struct pt_regs *regs)
{
	siginfo_t info;
	struct k_sigaction ka;
	int signr;

	current->thread.esp0 = (unsigned long) regs;

	if (!oldset)
		oldset = &current->blocked;

	signr = get_signal_to_deliver(&info, &ka, regs, NULL);
	if (signr > 0) {
		/* Whee!  Actually deliver the signal.  */
		handle_signal(signr, &ka, &info, oldset, regs);
		return 1;
	}

	/* Did we come from a system call? */
	if (regs->orig_d0 >= 0)
		/* Restart the system call - no handlers present */
		handle_restart(regs, NULL, 0);

	return 0;
}