signal.c

底层驱动开发

		err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext, 
					&compat_frame->regs, regs, in_syscall);
		sigset_64to32(&compat_set,set);
		err |= __copy_to_user(&compat_frame->uc.uc_sigmask, &compat_set, sizeof(compat_set));
	} else
#endif
	{	
		DBG(1,"setup_rt_frame: frame->info = 0x%p\n", &frame->info);
		err |= copy_siginfo_to_user(&frame->info, info);
		err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
		err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
		err |= __put_user(sas_ss_flags(regs->gr[30]),
				  &frame->uc.uc_stack.ss_flags);
		DBG(1,"setup_rt_frame: frame->uc = 0x%p\n", &frame->uc);
		DBG(1,"setup_rt_frame: frame->uc.uc_mcontext = 0x%p\n", &frame->uc.uc_mcontext);
		err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall);
		/* FIXME: Should probably be converted aswell for the compat case */
		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. The first words of tramp are used to
	   save the previous sigrestartblock trampoline that might be
	   on the stack. We start the sigreturn trampoline at 
	   SIGRESTARTBLOCK_TRAMP+X. */
	err |= __put_user(in_syscall ? INSN_LDI_R25_1 : INSN_LDI_R25_0,
			&frame->tramp[SIGRESTARTBLOCK_TRAMP+0]);
	err |= __put_user(INSN_LDI_R20, 
			&frame->tramp[SIGRESTARTBLOCK_TRAMP+1]);
	err |= __put_user(INSN_BLE_SR2_R0, 
			&frame->tramp[SIGRESTARTBLOCK_TRAMP+2]);
	err |= __put_user(INSN_NOP, &frame->tramp[SIGRESTARTBLOCK_TRAMP+3]);

#if DEBUG_SIG
	/* Assert that we're flushing in the correct space... */
	{
		int sid;
		asm ("mfsp %%sr3,%0" : "=r" (sid));
		DBG(1,"setup_rt_frame: Flushing 64 bytes at space %#x offset %p\n",
		       sid, frame->tramp);
	}
#endif

	flush_user_dcache_range((unsigned long) &frame->tramp[0],
			   (unsigned long) &frame->tramp[TRAMP_SIZE]);
	flush_user_icache_range((unsigned long) &frame->tramp[0],
			   (unsigned long) &frame->tramp[TRAMP_SIZE]);

	/* TRAMP Words 0-4, Lenght 5 = SIGRESTARTBLOCK_TRAMP
	 * TRAMP Words 5-9, Length 4 = SIGRETURN_TRAMP
	 * So the SIGRETURN_TRAMP is at the end of SIGRESTARTBLOCK_TRAMP
	 */
	rp = (unsigned long) &frame->tramp[SIGRESTARTBLOCK_TRAMP];

	if (err)
		goto give_sigsegv;

	haddr = A(ka->sa.sa_handler);
	/* The sa_handler may be a pointer to a function descriptor */
#ifdef __LP64__
	if(personality(current->personality) == PER_LINUX32) {
#endif
		if (haddr & PA_PLABEL_FDESC) {
			Elf32_Fdesc fdesc;
			Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3);

			err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));

			if (err)
				goto give_sigsegv;

			haddr = fdesc.addr;
			regs->gr[19] = fdesc.gp;
		}
#ifdef __LP64__
	} else {
		Elf64_Fdesc fdesc;
		Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3);
		
		err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc));
		
		if (err)
			goto give_sigsegv;
		
		haddr = fdesc.addr;
		regs->gr[19] = fdesc.gp;
		DBG(1,"setup_rt_frame: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n",
		     haddr, regs->gr[19], in_syscall);
	}
#endif

	/* The syscall return path will create IAOQ values from r31.
	 */
	sigframe_size = PARISC_RT_SIGFRAME_SIZE;
#ifdef __LP64__
	if(personality(current->personality) == PER_LINUX32)
		sigframe_size = PARISC_RT_SIGFRAME_SIZE32;
#endif
	if (in_syscall) {
		regs->gr[31] = haddr;
#ifdef __LP64__
		if(personality(current->personality) == PER_LINUX)
			sigframe_size |= 1;
#endif
	} else {
		unsigned long psw = USER_PSW;
#ifdef __LP64__
		if(personality(current->personality) == PER_LINUX)
			psw |= PSW_W;
#endif

		/* If we are singlestepping, arrange a trap to be delivered
		   when we return to userspace. Note the semantics -- we
		   should trap before the first insn in the handler is
		   executed. Ref:
			http://sources.redhat.com/ml/gdb/2004-11/msg00245.html
		 */
		if (pa_psw(current)->r) {
			pa_psw(current)->r = 0;
			psw |= PSW_R;
			mtctl(-1, 0);
		}

		regs->gr[0] = psw;
		regs->iaoq[0] = haddr | 3;
		regs->iaoq[1] = regs->iaoq[0] + 4;
	}

	regs->gr[2]  = rp;                /* userland return pointer */
	regs->gr[26] = sig;               /* signal number */
	
#ifdef __LP64__
	if(personality(current->personality) == PER_LINUX32){
		regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */
		regs->gr[24] = A(&compat_frame->uc);   /* ucontext pointer */
	} else
#endif
	{		
		regs->gr[25] = A(&frame->info); /* siginfo pointer */
		regs->gr[24] = A(&frame->uc);   /* ucontext pointer */
	}
	
	DBG(1,"setup_rt_frame: making sigreturn frame: %#lx + %#lx = %#lx\n",
	       regs->gr[30], sigframe_size,
	       regs->gr[30] + sigframe_size);
	/* Raise the user stack pointer to make a proper call frame. */
	regs->gr[30] = (A(frame) + sigframe_size);


	DBG(1,"setup_rt_frame: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n",
	       current->comm, current->pid, frame, regs->gr[30],
	       regs->iaoq[0], regs->iaoq[1], rp);

	return 1;

give_sigsegv:
	DBG(1,"setup_rt_frame: sending SIGSEGV\n");
	if (sig == SIGSEGV)
		ka->sa.sa_handler = SIG_DFL;
	si.si_signo = SIGSEGV;
	si.si_errno = 0;
	si.si_code = SI_KERNEL;
	si.si_pid = current->pid;
	si.si_uid = current->uid;
	si.si_addr = frame;
	force_sig_info(SIGSEGV, &si, current);
	return 0;
}

/*
 * OK, we're invoking a handler.
 */	

static long
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
		sigset_t *oldset, struct pt_regs *regs, int in_syscall)
{
	DBG(1,"handle_signal: sig=%ld, ka=%p, info=%p, oldset=%p, regs=%p\n",
	       sig, ka, info, oldset, regs);
	
	/* Set up the stack frame */
	if (!setup_rt_frame(sig, ka, info, oldset, regs, in_syscall))
		return 0;

	spin_lock_irq(&current->sighand->siglock);
	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
	if (!(ka->sa.sa_flags & SA_NODEFER))
		sigaddset(&current->blocked,sig);
	recalc_sigpending();
	spin_unlock_irq(&current->sighand->siglock);
	return 1;
}

/*
 * 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.
 *
 * We need to be able to restore the syscall arguments (r21-r26) to
 * restart syscalls.  Thus, the syscall path should save them in the
 * pt_regs structure (it's okay to do so since they are caller-save
 * registers).  As noted below, the syscall number gets restored for
 * us due to the magic of delayed branching.
 */

asmlinkage int
do_signal(sigset_t *oldset, struct pt_regs *regs, int in_syscall)
{
	siginfo_t info;
	struct k_sigaction ka;
	int signr;

	DBG(1,"\ndo_signal: oldset=0x%p, regs=0x%p, sr7 %#lx, in_syscall=%d\n",
	       oldset, regs, regs->sr[7], in_syscall);

	/* Everyone else checks to see if they are in kernel mode at
	   this point and exits if that's the case.  I'm not sure why
	   we would be called in that case, but for some reason we
	   are. */

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

	DBG(1,"do_signal: oldset %08lx / %08lx\n", 
		oldset->sig[0], oldset->sig[1]);


	/* May need to force signal if handle_signal failed to deliver */
	while (1) {
	  
		signr = get_signal_to_deliver(&info, &ka, regs, NULL);
		DBG(3,"do_signal: signr = %d, regs->gr[28] = %ld\n", signr, regs->gr[28]); 
	
		if (signr <= 0)
		  break;
		
		/* Restart a system call if necessary. */
		if (in_syscall) {
			/* Check the return code */
			switch (regs->gr[28]) {
		        case -ERESTART_RESTARTBLOCK:
				current_thread_info()->restart_block.fn = do_no_restart_syscall;
			case -ERESTARTNOHAND:
				DBG(1,"ERESTARTNOHAND: returning -EINTR\n");
				regs->gr[28] = -EINTR;
				break;

			case -ERESTARTSYS:
				if (!(ka.sa.sa_flags & SA_RESTART)) {
					DBG(1,"ERESTARTSYS: putting -EINTR\n");
					regs->gr[28] = -EINTR;
					break;
				}
			/* fallthrough */
			case -ERESTARTNOINTR:
				/* A syscall is just a branch, so all
				   we have to do is fiddle the return pointer. */
				regs->gr[31] -= 8; /* delayed branching */
				/* Preserve original r28. */
				regs->gr[28] = regs->orig_r28;
				break;
			}
		}
		/* Whee!  Actually deliver the signal.  If the
		   delivery failed, we need to continue to iterate in
		   this loop so we can deliver the SIGSEGV... */
		if (handle_signal(signr, &info, &ka, oldset, regs, in_syscall)) {
			DBG(1,KERN_DEBUG "do_signal: Exit (success), regs->gr[28] = %ld\n",
				regs->gr[28]);
			return 1;
		}
	}
	/* end of while(1) looping forever if we can't force a signal */

	/* Did we come from a system call? */
	if (in_syscall) {
		/* Restart the system call - no handlers present */
		if (regs->gr[28] == -ERESTART_RESTARTBLOCK) {
			unsigned int *usp = (unsigned int *)regs->gr[30];

			/* Setup a trampoline to restart the syscall
			 * with __NR_restart_syscall
			 *
			 *  0: <return address (orig r31)>
			 *  4: <2nd half for 64-bit>
			 *  8: ldw 0(%sp), %r31
			 * 12: be 0x100(%sr2, %r0)
			 * 16: ldi __NR_restart_syscall, %r20
			 */
#ifndef __LP64__
			put_user(regs->gr[31], &usp[0]);
			put_user(0x0fc0109f, &usp[2]);
#else
			put_user(regs->gr[31] >> 32, &usp[0]);
			put_user(regs->gr[31] & 0xffffffff, &usp[1]);
			put_user(0x0fc010df, &usp[2]);
#endif
			put_user(0xe0008200, &usp[3]);
			put_user(0x34140000, &usp[4]);

			/* Stack is 64-byte aligned, and we only 
			 * need to flush 1 cache line */
			asm("fdc 0(%%sr3, %0)\n"
			    "fic 0(%%sr3, %0)\n"
			    "sync\n"
			    : : "r"(regs->gr[30]));

			regs->gr[31] = regs->gr[30] + 8;
			/* Preserve original r28. */
			regs->gr[28] = regs->orig_r28;
		} else if (regs->gr[28] == -ERESTARTNOHAND ||
		           regs->gr[28] == -ERESTARTSYS ||
		           regs->gr[28] == -ERESTARTNOINTR) {
			/* Hooray for delayed branching.  We don't
                           have to restore %r20 (the system call
                           number) because it gets loaded in the delay
                           slot of the branch external instruction. */
			regs->gr[31] -= 8;
			/* Preserve original r28. */
			regs->gr[28] = regs->orig_r28;
		}
	}
	
	DBG(1,"do_signal: Exit (not delivered), regs->gr[28] = %ld\n", 
		regs->gr[28]);

	return 0;
}