static int setup_rt_frame()

in kernel/signal.c [149:201]

• 33 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;
	unsigned long return_ip;
	int err = 0;

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

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

	/* Create siginfo.  */
	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->sp);
	err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);

	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));

	if (err)
		return -EFAULT;

	/* trampoline - the desired return ip is the retcode itself */
	return_ip = (unsigned long)&frame->retcode;
	/* This is:
		l.ori r11,r0,__NR_sigreturn
		l.sys 1
	 */
	err |= __put_user(0xa960,             (short __user *)(frame->retcode + 0));
	err |= __put_user(__NR_rt_sigreturn,  (short __user *)(frame->retcode + 2));
	err |= __put_user(0x20000001, (unsigned long __user *)(frame->retcode + 4));
	err |= __put_user(0x15000000, (unsigned long __user *)(frame->retcode + 8));

	if (err)
		return -EFAULT;

	/* Set up registers for signal handler */
	regs->pc = (unsigned long)ksig->ka.sa.sa_handler; /* what we enter NOW */
	regs->gpr[9] = (unsigned long)return_ip;     /* what we enter LATER */
	regs->gpr[3] = (unsigned long)ksig->sig;           /* arg 1: signo */
	regs->gpr[4] = (unsigned long)&frame->info;  /* arg 2: (siginfo_t*) */
	regs->gpr[5] = (unsigned long)&frame->uc;    /* arg 3: ucontext */

	/* actually move the usp to reflect the stacked frame */
	regs->sp = (unsigned long)frame;

	return 0;
}