signal32.c

讲述linux的初始化过程

		       sframep, pc, signr);
#endif
		/* Don't change signal code and address, so that
		 * post mortem debuggers can have a look.
		 */
		do_exit(SIGILL);
	}

	sc = &sframep->sig_context;

	/* We've already made sure frame pointer isn't in kernel space... */
	err = __put_user((sas_ss_flags(regs->u_regs[UREG_FP]) == SS_ONSTACK),
			 &sc->sigc_onstack);
	
	switch (_NSIG_WORDS) {
	case 4: seta[7] = (oldset->sig[3] >> 32);
	        seta[6] = oldset->sig[3];
	case 3: seta[5] = (oldset->sig[2] >> 32);
	        seta[4] = oldset->sig[2];
	case 2: seta[3] = (oldset->sig[1] >> 32);
	        seta[2] = oldset->sig[1];
	case 1: seta[1] = (oldset->sig[0] >> 32);
	        seta[0] = oldset->sig[0];
	}
	err |= __put_user(seta[0], &sc->sigc_mask);
	err |= __copy_to_user(sframep->extramask, seta + 1,
			      (_NSIG_WORDS32 - 1) * sizeof(unsigned));
	err |= __put_user(regs->u_regs[UREG_FP], &sc->sigc_sp);
	err |= __put_user(pc, &sc->sigc_pc);
	err |= __put_user(npc, &sc->sigc_npc);
	psr = tstate_to_psr (regs->tstate);
	if(current->thread.fpsaved[0] & FPRS_FEF)
		psr |= PSR_EF;
	err |= __put_user(psr, &sc->sigc_psr);
	err |= __put_user(regs->u_regs[UREG_G1], &sc->sigc_g1);
	err |= __put_user(regs->u_regs[UREG_I0], &sc->sigc_o0);
	err |= __put_user(current->thread.w_saved, &sc->sigc_oswins);
#if 0
/* w_saved is not currently used... */
	if(current->thread.w_saved)
		for(window = 0; window < current->thread.w_saved; window++) {
			sc->sigc_spbuf[window] =
				(char *)current->thread.rwbuf_stkptrs[window];
			err |= copy_to_user(&sc->sigc_wbuf[window],
					    &current->thread.reg_window[window],
					    sizeof(struct reg_window));
		}
	else
#endif	
		err |= copy_in_user((u32 *)sframep,
				    (u32 *)(regs->u_regs[UREG_FP]),
				    sizeof(struct reg_window32));
		       
	current->thread.w_saved = 0; /* So process is allowed to execute. */
	err |= __put_user(signr, &sframep->sig_num);
	sig_address = NULL;
	sig_code = 0;
	if (SI_FROMKERNEL (info) && (info->si_code & __SI_MASK) == __SI_FAULT) {
		sig_address = info->si_addr;
		switch (signr) {
		case SIGSEGV:
			switch (info->si_code) {
			case SEGV_MAPERR: sig_code = SUBSIG_NOMAPPING; break;
			default: sig_code = SUBSIG_PROTECTION; break;
			}
			break;
		case SIGILL:
			switch (info->si_code) {
			case ILL_ILLOPC: sig_code = SUBSIG_ILLINST; break;
			case ILL_PRVOPC: sig_code = SUBSIG_PRIVINST; break;
			case ILL_ILLTRP: sig_code = SUBSIG_BADTRAP (info->si_trapno); break;
			default: sig_code = SUBSIG_STACK; break;
			}
			break;
		case SIGFPE:
			switch (info->si_code) {
			case FPE_INTDIV: sig_code = SUBSIG_IDIVZERO; break;
			case FPE_INTOVF: sig_code = SUBSIG_FPINTOVFL; break;
			case FPE_FLTDIV: sig_code = SUBSIG_FPDIVZERO; break;
			case FPE_FLTOVF: sig_code = SUBSIG_FPOVFLOW; break;
			case FPE_FLTUND: sig_code = SUBSIG_FPUNFLOW; break;
			case FPE_FLTRES: sig_code = SUBSIG_FPINEXACT; break;
			case FPE_FLTINV: sig_code = SUBSIG_FPOPERROR; break;
			default: sig_code = SUBSIG_FPERROR; break;
			}
			break;
		case SIGBUS:
			switch (info->si_code) {
			case BUS_ADRALN: sig_code = SUBSIG_ALIGNMENT; break;
			case BUS_ADRERR: sig_code = SUBSIG_MISCERROR; break;
			default: sig_code = SUBSIG_BUSTIMEOUT; break;
			}
			break;
		case SIGEMT:
			switch (info->si_code) {
			case EMT_TAGOVF: sig_code = SUBSIG_TAG; break;
			}
			break;
		case SIGSYS:
			if (info->si_code == (__SI_FAULT|0x100)) {
				/* See sys_sunos32.c */
				sig_code = info->si_trapno;
				break;
			}
		default:
			sig_address = NULL;
		}
	}
	err |= __put_user((long)sig_address, &sframep->sig_address);
	err |= __put_user(sig_code, &sframep->sig_code);
	err |= __put_user((u64)sc, &sframep->sig_scptr);
	if (err)
		goto sigsegv;

	regs->u_regs[UREG_FP] = (unsigned long) sframep;
	regs->tpc = (unsigned long) sa->sa_handler;
	regs->tnpc = (regs->tpc + 4);
	return;

sigsegv:
	do_exit(SIGSEGV);
}


static inline int save_fpu_state32(struct pt_regs *regs, __siginfo_fpu_t *fpu)
{
	unsigned long *fpregs = (unsigned long *)(((char *)current) + AOFF_task_fpregs);
	unsigned long fprs;
	int err = 0;
	
	fprs = current->thread.fpsaved[0];
	if (fprs & FPRS_DL)
		err |= copy_to_user(&fpu->si_float_regs[0], fpregs,
				    (sizeof(unsigned int) * 32));
	if (fprs & FPRS_DU)
		err |= copy_to_user(&fpu->si_float_regs[32], fpregs+16,
				    (sizeof(unsigned int) * 32));
	err |= __put_user(current->thread.xfsr[0], &fpu->si_fsr);
	err |= __put_user(current->thread.gsr[0], &fpu->si_gsr);
	err |= __put_user(fprs, &fpu->si_fprs);

	return err;
}

static inline void new_setup_frame32(struct k_sigaction *ka, struct pt_regs *regs,
				     int signo, sigset_t *oldset)
{
	struct new_signal_frame32 *sf;
	int sigframe_size;
	u32 psr;
	int i, err;
	unsigned seta[_NSIG_WORDS32];

	/* 1. Make sure everything is clean */
	synchronize_user_stack();
	save_and_clear_fpu();
	
	sigframe_size = NF_ALIGNEDSZ;
	if (!(current->thread.fpsaved[0] & FPRS_FEF))
		sigframe_size -= sizeof(__siginfo_fpu_t);

	sf = (struct new_signal_frame32 *)get_sigframe(&ka->sa, regs, sigframe_size);
	
	if (invalid_frame_pointer (sf, sigframe_size)) {
#ifdef DEBUG_SIGNALS
		printk("new_setup_frame32(%s:%d): invalid_frame_pointer(%p, %d)\n",
		       current->comm, current->pid, sf, sigframe_size);
#endif
		goto sigill;
	}

	if (current->thread.w_saved != 0) {
#ifdef DEBUG_SIGNALS
		printk ("%s[%d]: Invalid user stack frame for "
			"signal delivery.\n", current->comm, current->pid);
#endif
		goto sigill;
	}

	/* 2. Save the current process state */
	err  = put_user(regs->tpc, &sf->info.si_regs.pc);
	err |= __put_user(regs->tnpc, &sf->info.si_regs.npc);
	err |= __put_user(regs->y, &sf->info.si_regs.y);
	psr = tstate_to_psr (regs->tstate);
	if(current->thread.fpsaved[0] & FPRS_FEF)
		psr |= PSR_EF;
	err |= __put_user(psr, &sf->info.si_regs.psr);
	for (i = 0; i < 16; i++)
		err |= __put_user(regs->u_regs[i], &sf->info.si_regs.u_regs[i]);
	err |= __put_user(sizeof(siginfo_extra_v8plus_t), &sf->extra_size);
	err |= __put_user(SIGINFO_EXTRA_V8PLUS_MAGIC, &sf->v8plus.g_upper[0]);
	for (i = 1; i < 16; i++)
		err |= __put_user(((u32 *)regs->u_regs)[2*i], &sf->v8plus.g_upper[i]);

	if (psr & PSR_EF) {
		err |= save_fpu_state32(regs, &sf->fpu_state);
		err |= __put_user((u64)&sf->fpu_state, &sf->fpu_save);
	} else {
		err |= __put_user(0, &sf->fpu_save);
	}

	switch (_NSIG_WORDS) {
	case 4: seta[7] = (oldset->sig[3] >> 32);
	        seta[6] = oldset->sig[3];
	case 3: seta[5] = (oldset->sig[2] >> 32);
	        seta[4] = oldset->sig[2];
	case 2: seta[3] = (oldset->sig[1] >> 32);
	        seta[2] = oldset->sig[1];
	case 1: seta[1] = (oldset->sig[0] >> 32);
	        seta[0] = oldset->sig[0];
	}
	err |= __put_user(seta[0], &sf->info.si_mask);
	err |= __copy_to_user(sf->extramask, seta + 1,
			      (_NSIG_WORDS32 - 1) * sizeof(unsigned));

	err |= copy_in_user((u32 *)sf,
			    (u32 *)(regs->u_regs[UREG_FP]),
			    sizeof(struct reg_window32));
	
	if (err)
		goto sigsegv;

	/* 3. signal handler back-trampoline and parameters */
	regs->u_regs[UREG_FP] = (unsigned long) sf;
	regs->u_regs[UREG_I0] = signo;
	regs->u_regs[UREG_I1] = (unsigned long) &sf->info;

	/* 4. signal handler */
	regs->tpc = (unsigned long) ka->sa.sa_handler;
	regs->tnpc = (regs->tpc + 4);

	/* 5. return to kernel instructions */
	if (ka->ka_restorer)
		regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
	else {
		/* Flush instruction space. */
		unsigned long address = ((unsigned long)&(sf->insns[0]));
		pgd_t *pgdp = pgd_offset(current->mm, address);
		pmd_t *pmdp = pmd_offset(pgdp, address);
		pte_t *ptep = pte_offset(pmdp, address);

		regs->u_regs[UREG_I7] = (unsigned long) (&(sf->insns[0]) - 2);
	
		err  = __put_user(0x821020d8, &sf->insns[0]); /*mov __NR_sigreturn, %g1*/
		err |= __put_user(0x91d02010, &sf->insns[1]); /*t 0x10*/
		if(err)
			goto sigsegv;

		if(pte_present(*ptep)) {
			unsigned long page = (unsigned long) page_address(pte_page(*ptep));

			__asm__ __volatile__("
			membar	#StoreStore
			flush	%0 + %1"
			: : "r" (page), "r" (address & (PAGE_SIZE - 1))
			: "memory");
		}
	}
	return;

sigill:
	do_exit(SIGILL);
sigsegv:
	do_exit(SIGSEGV);
}

/* Setup a Solaris stack frame */
static inline void
setup_svr4_frame32(struct sigaction *sa, unsigned long pc, unsigned long npc,
		   struct pt_regs *regs, int signr, sigset_t *oldset)
{
	svr4_signal_frame_t *sfp;
	svr4_gregset_t  *gr;
	svr4_siginfo_t  *si;
	svr4_mcontext_t *mc;
	svr4_gwindows_t *gw;
	svr4_ucontext_t *uc;
	svr4_sigset_t setv;
#if 0	
	int window = 0;
#endif	
	unsigned psr;
	int i, err;

	synchronize_user_stack();
	save_and_clear_fpu();
	
	regs->u_regs[UREG_FP] &= 0x00000000ffffffffUL;
	sfp = (svr4_signal_frame_t *) get_sigframe(sa, regs, REGWIN_SZ + SVR4_SF_ALIGNED);

	if (invalid_frame_pointer (sfp, sizeof (*sfp))){
#ifdef DEBUG_SIGNALS
		printk ("Invalid stack frame\n");
#endif
		do_exit(SIGILL);
	}

	/* Start with a clean frame pointer and fill it */
	err = clear_user(sfp, sizeof (*sfp));

	/* Setup convenience variables */
	si = &sfp->si;
	uc = &sfp->uc;
	gw = &sfp->gw;
	mc = &uc->mcontext;
	gr = &mc->greg;
	
	/* FIXME: where am I supposed to put this?
	 * sc->sigc_onstack = old_status;
	 * anyways, it does not look like it is used for anything at all.
	 */
	setv.sigbits[0] = oldset->sig[0];
	setv.sigbits[1] = (oldset->sig[0] >> 32);
	if (_NSIG_WORDS >= 2) {
		setv.sigbits[2] = oldset->sig[1];
		setv.sigbits[3] = (oldset->sig[1] >> 32);
		err |= __copy_to_user(&uc->sigmask, &setv, sizeof(svr4_sigset_t));
	} else
		err |= __copy_to_user(&uc->sigmask, &setv, 2 * sizeof(unsigned));
	
	/* Store registers */
	err |= __put_user(regs->tpc, &((*gr) [SVR4_PC]));
	err |= __put_user(regs->tnpc, &((*gr) [SVR4_NPC]));
	psr = tstate_to_psr (regs->tstate);
	if(current->thread.fpsaved[0] & FPRS_FEF)
		psr |= PSR_EF;
	err |= __put_user(psr, &((*gr) [SVR4_PSR]));
	err |= __put_user(regs->y, &((*gr) [SVR4_Y]));
	
	/* Copy g [1..7] and o [0..7] registers */
	for (i = 0; i < 7; i++)
		err |= __put_user(regs->u_regs[UREG_G1+i], (&(*gr)[SVR4_G1])+i);
	for (i = 0; i < 8; i++)
		err |= __put_user(regs->u_regs[UREG_I0+i], (&(*gr)[SVR4_O0])+i);

	/* Setup sigaltstack */
	err |= __put_user(current->sas_ss_sp, &uc->stack.sp);
	err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &uc->stack.flags);
	err |= __put_user(current->sas_ss_size, &uc->stack.size);

	/* Save the currently window file: */

	/* 1. Link sfp->uc->gwins to our windows */
	err |= __put_user((u32)(long)gw, &mc->gwin);
	    
	/* 2. Number of windows to restore at setcontext (): */
	err |= __put_user(current->thread.w_saved, &gw->count);

	/* 3. Save each valid window
	 *    Currently, it makes a copy of the windows from the kernel copy.
	 *    David's code for SunOS, makes the copy but keeps the pointer to
	 *    the kernel.  My version makes the pointer point to a userland 
	 *    copy of those.  Mhm, I wonder if I shouldn't just ignore those
	 *    on setcontext and use those that are on the kernel, the signal
	 *    handler should not be modyfing those, mhm.
	 *
	 *    These windows are just used in case synchronize_user_stack failed
	 *    to flush the user windows.
	 */
#if 0	 
	for(window = 0; window < current->thread.w_saved; window++) {
		err |= __put_user((int *) &(gw->win [window]),
				  (int **)gw->winptr +window );
		err |= copy_to_user(&gw->win [window],
				    &current->thread.reg_window [window],
				    sizeof (svr4_rwindow_t));
		err |= __put_user(0, (int *)gw->winptr + window);
	}
#endif	

	/* 4. We just pay attention to the gw->count field on setcontext */
	current->thread.w_saved = 0; /* So process is allowed to execute. */

	/* Setup the signal information.  Solaris expects a bunch of
	 * information to be passed to the signal handler, we don't provide
	 * that much currently, should use siginfo.
	 */
	err |= __put_user(signr, &si->siginfo.signo);
	err |= __put_user(SVR4_SINOINFO, &si->siginfo.code);
	if (err)
		goto sigsegv;

	regs->u_regs[UREG_FP] = (unsigned long) sfp;
	regs->tpc = (unsigned long) sa->sa_handler;
	regs->tnpc = (regs->tpc + 4);

#ifdef DEBUG_SIGNALS
	printk ("Solaris-frame: %x %x\n", (int) regs->tpc, (int) regs->tnpc);
#endif
	/* Arguments passed to signal handler */
	if (regs->u_regs [14]){
		struct reg_window32 *rw = (struct reg_window32 *)
			(regs->u_regs [14] & 0x00000000ffffffffUL);

		err |= __put_user(signr, &rw->ins [0]);
		err |= __put_user((u64)si, &rw->ins [1]);
		err |= __put_user((u64)uc, &rw->ins [2]);
		err |= __put_user((u64)sfp, &rw->ins [6]);	/* frame pointer */
		if (err)
			goto sigsegv;

		regs->u_regs[UREG_I0] = signr;
		regs->u_regs[UREG_I1] = (u32)(u64) si;
		regs->u_regs[UREG_I2] = (u32)(u64) uc;
	}
	return;

sigsegv:
	do_exit(SIGSEGV);
}

asmlinkage int
svr4_getcontext(svr4_ucontext_t *uc, struct pt_regs *regs)
{
	svr4_gregset_t  *gr;
	svr4_mcontext_t *mc;
	svr4_sigset_t setv;
	int i, err;

	synchronize_user_stack();
	save_and_clear_fpu();
	
	if (current->thread.w_saved){
		printk ("Uh oh, w_saved is not zero (%d)\n", (int) current->thread.w_saved);
		do_exit (SIGSEGV);
	}
	err = clear_user(uc, sizeof (*uc));

	/* Setup convenience variables */
	mc = &uc->mcontext;
	gr = &mc->greg;

	setv.sigbits[0] = current->blocked.sig[0];
	setv.sigbits[1] = (current->blocked.sig[0] >> 32);
	if (_NSIG_WORDS >= 2) {
		setv.sigbits[2] = current->blocked.sig[1];
		setv.sigbits[3] = (current->blocked.sig[1] >> 32);
		err |= __copy_to_user(&uc->sigmask, &setv, sizeof(svr4_sigset_t));
	} else
		err |= __copy_to_user(&uc->sigmask, &setv, 2 * sizeof(unsigned));

	/* Store registers */
	err |= __put_user(regs->tpc, &uc->mcontext.greg [SVR4_PC]);
	err |= __put_user(regs->tnpc, &uc->mcontext.greg [SVR4_NPC]);
#if 1
	err |= __put_user(0, &uc->mcontext.greg [SVR4_PSR]);
#else
	i = tstate_to_psr(regs->tstate) & ~PSR_EF;		   
	if (current->thread.fpsaved[0] & FPRS_FEF)
		i |= PSR_EF;
	err |= __put_user(i, &uc->mcontext.greg [SVR4_PSR]);
#endif
	err |= __put_user(regs->y, &uc->mcontext.greg [SVR4_Y]);
	
	/* Copy g [1..7] and o [0..7] registers */
	for (i = 0; i < 7; i++)
		err |= __put_user(regs->u_regs[UREG_G1+i], (&(*gr)[SVR4_G1])+i);
	for (i = 0; i < 8; i++)
		err |= __put_user(regs->u_regs[UREG_I0+i], (&(*gr)[SVR4_O0])+i);

	/* Setup sigaltstack */
	err |= __put_user(current->sas_ss_sp, &uc->stack.sp);
	err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &uc->stack.flags);
	err |= __put_user(current->sas_ss_size, &uc->stack.size);

	/* The register file is not saved
	 * we have already stuffed all of it with sync_user_stack
	 */
	return (err ? -EFAULT : 0);
}


/* Set the context for a svr4 application, this is Solaris way to sigreturn */
asmlinkage int svr4_setcontext(svr4_ucontext_t *c, struct pt_regs *regs)
{
	struct thread_struct *tp = &current->thread;
	svr4_gregset_t  *gr;
	u32 pc, npc, psr;
	sigset_t set;
	svr4_sigset_t setv;
	int i, err;
	stack_t st;
	
	/* Fixme: restore windows, or is this already taken care of in
	 * svr4_setup_frame when sync_user_windows is done?
	 */
	flush_user_windows();
	
	if (tp->w_saved){
		printk ("Uh oh, w_saved is: 0x%x\n", tp->w_saved);
		goto sigsegv;
	}
	if (((unsigned long) c) & 3){
		printk ("Unaligned structure passed\n");
		goto sigsegv;
	}

	if(!__access_ok((unsigned long)c, sizeof(*c))) {
		/* Miguel, add nice debugging msg _here_. ;-) */
		goto sigsegv;
	}

	/* Check for valid PC and nPC */