static int setup_rt_frame()

in kernel/signal.c [154:227]

• 49 lines of code
• 5 McCabe index (conditional complexity)

static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
			  struct pt_regs *regs)
{
	struct rt_sigframe __user *frame;
	int err = 0, sig = ksig->sig;
	unsigned long address = 0;
	pmd_t *pmdp;
	pte_t *ptep;

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

	if (!access_ok(frame, sizeof(*frame)))
		return -EFAULT;

	if (ksig->ka.sa.sa_flags & SA_SIGINFO)
		err |= copy_siginfo_to_user(&frame->info, &ksig->info);

	/* Create the ucontext. */
	err |= __put_user(0, &frame->uc.uc_flags);
	err |= __put_user(NULL, &frame->uc.uc_link);
	err |= __save_altstack(&frame->uc.uc_stack, regs->r1);
	err |= setup_sigcontext(&frame->uc.uc_mcontext,
			regs, set->sig[0]);
	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	/* Set up to return from userspace. If provided, use a stub
	 already in userspace. */
	/* minus 8 is offset to cater for "rtsd r15,8" */
	/* addi r12, r0, __NR_sigreturn */
	err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
			frame->tramp + 0);
	/* brki r14, 0x8 */
	err |= __put_user(0xb9cc0008, frame->tramp + 1);

	/* Return from sighandler will jump to the tramp.
	 Negative 8 offset because return is rtsd r15, 8 */
	regs->r15 = ((unsigned long)frame->tramp)-8;

	address = ((unsigned long)frame->tramp);
	pmdp = pmd_off(current->mm, address);

	preempt_disable();
	ptep = pte_offset_map(pmdp, address);
	if (pte_present(*ptep)) {
		address = (unsigned long) page_address(pte_page(*ptep));
		/* MS: I need add offset in page */
		address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
		/* MS address is virtual */
		address = __virt_to_phys(address);
		invalidate_icache_range(address, address + 8);
		flush_dcache_range(address, address + 8);
	}
	pte_unmap(ptep);
	preempt_enable();
	if (err)
		return -EFAULT;

	/* Set up registers for signal handler */
	regs->r1 = (unsigned long) frame;

	/* Signal handler args: */
	regs->r5 = sig; /* arg 0: signum */
	regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
	regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
	/* Offset to handle microblaze rtid r14, 0 */
	regs->pc = (unsigned long)ksig->ka.sa.sa_handler;

#ifdef DEBUG_SIG
	pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n",
		current->comm, current->pid, frame, regs->pc);
#endif

	return 0;
}