/* * linux/arch/cris/kernel/signal.c * * Based on arch/i386/kernel/signal.c by * Copyright (C) 1991, 1992 Linus Torvalds * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson * * * Ideas also taken from arch/arm. * * Copyright (C) 2000, 2001 Axis Communications AB * * Authors: Bjorn Wesen (bjornw@axis.com) * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define DEBUG_SIG 0 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) /* a syscall in Linux/CRIS is a break 13 instruction which is 2 bytes */ /* manipulate regs so that upon return, it will be re-executed */ /* We rely on that pc points to the instruction after "break 13", so the * library must never do strange things like putting it in a delay slot. */ #define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->irp -= 2; int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs); /* * Atomically swap in the new signal mask, and wait for a signal. Define * dummy arguments to be able to reach the regs argument. (Note that this * arrangement relies on old_sigset_t occupying one register.) */ int sys_sigsuspend(old_sigset_t mask, long r11, long r12, long r13, long mof, long srp, struct pt_regs *regs) { sigset_t saveset; mask &= _BLOCKABLE; spin_lock_irq(¤t->sighand->siglock); saveset = current->blocked; siginitset(¤t->blocked, mask); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); regs->r10 = -EINTR; while (1) { current->state = TASK_INTERRUPTIBLE; schedule(); if (do_signal(0, &saveset, regs)) /* We will get here twice: once to call the signal handler, then again to return from the sigsuspend system call. When calling the signal handler, R10 holds the signal number as set through do_signal. The sigsuspend call will return with the restored value set above; always -EINTR. */ return regs->r10; } } /* Define dummy arguments to be able to reach the regs argument. (Note that * this arrangement relies on size_t occupying one register.) */ int sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize, long r12, long r13, long mof, long srp, struct pt_regs *regs) { sigset_t saveset, newset; /* XXX: Don't preclude handling different sized sigset_t's. */ if (sigsetsize != sizeof(sigset_t)) return -EINVAL; if (copy_from_user(&newset, unewset, sizeof(newset))) return -EFAULT; sigdelsetmask(&newset, ~_BLOCKABLE); spin_lock_irq(¤t->sighand->siglock); saveset = current->blocked; current->blocked = newset; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); regs->r10 = -EINTR; while (1) { current->state = TASK_INTERRUPTIBLE; schedule(); if (do_signal(0, &saveset, regs)) /* We will get here twice: once to call the signal handler, then again to return from the sigsuspend system call. When calling the signal handler, R10 holds the signal number as set through do_signal. The sigsuspend call will return with the restored value set above; always -EINTR. */ return regs->r10; } } int sys_sigaction(int sig, const struct old_sigaction __user *act, struct old_sigaction *oact) { struct k_sigaction new_ka, old_ka; int ret; if (act) { old_sigset_t mask; if (!access_ok(VERIFY_READ, act, sizeof(*act)) || __get_user(new_ka.sa.sa_handler, &act->sa_handler) || __get_user(new_ka.sa.sa_restorer, &act->sa_restorer)) return -EFAULT; __get_user(new_ka.sa.sa_flags, &act->sa_flags); __get_user(mask, &act->sa_mask); siginitset(&new_ka.sa.sa_mask, mask); } ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL); if (!ret && oact) { if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || __put_user(old_ka.sa.sa_handler, &oact->sa_handler) || __put_user(old_ka.sa.sa_restorer, &oact->sa_restorer)) return -EFAULT; __put_user(old_ka.sa.sa_flags, &oact->sa_flags); __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask); } return ret; } int sys_sigaltstack(const stack_t *uss, stack_t __user *uoss) { return do_sigaltstack(uss, uoss, rdusp()); } /* * Do a signal return; undo the signal stack. */ struct sigframe { struct sigcontext sc; unsigned long extramask[_NSIG_WORDS-1]; unsigned char retcode[8]; /* trampoline code */ }; struct rt_sigframe { struct siginfo *pinfo; void *puc; struct siginfo info; struct ucontext uc; unsigned char retcode[8]; /* trampoline code */ }; static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) { unsigned int err = 0; unsigned long old_usp; /* Always make any pending restarted system calls return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; /* restore the regs from &sc->regs (same as sc, since regs is first) * (sc is already checked for VERIFY_READ since the sigframe was * checked in sys_sigreturn previously) */ if (__copy_from_user(regs, sc, sizeof(struct pt_regs))) goto badframe; /* make sure the U-flag is set so user-mode cannot fool us */ regs->dccr |= 1 << 8; /* restore the old USP as it was before we stacked the sc etc. * (we cannot just pop the sigcontext since we aligned the sp and * stuff after pushing it) */ err |= __get_user(old_usp, &sc->usp); wrusp(old_usp); /* TODO: the other ports use regs->orig_XX to disable syscall checks * after this completes, but we don't use that mechanism. maybe we can * use it now ? */ return err; badframe: return 1; } /* Define dummy arguments to be able to reach the regs argument. */ asmlinkage int sys_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp, struct pt_regs *regs) { struct sigframe __user *frame = (struct sigframe *)rdusp(); sigset_t set; /* * Since we stacked the signal on a dword boundary, * then frame should be dword aligned here. If it's * not, then the user is trying to mess with us. */ if (((long)frame) & 3) goto badframe; if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) goto badframe; if (__get_user(set.sig[0], &frame->sc.oldmask) || (_NSIG_WORDS > 1 && __copy_from_user(&set.sig[1], frame->extramask, sizeof(frame->extramask)))) goto badframe; sigdelsetmask(&set, ~_BLOCKABLE); spin_lock_irq(¤t->sighand->siglock); current->blocked = set; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); if (restore_sigcontext(regs, &frame->sc)) goto badframe; /* TODO: SIGTRAP when single-stepping as in arm ? */ return regs->r10; badframe: force_sig(SIGSEGV, current); return 0; } /* Define dummy arguments to be able to reach the regs argument. */ asmlinkage int sys_rt_sigreturn(long r10, long r11, long r12, long r13, long mof, long srp, struct pt_regs *regs) { struct rt_sigframe __user *frame = (struct rt_sigframe *)rdusp(); sigset_t set; /* * Since we stacked the signal on a dword boundary, * then frame should be dword aligned here. If it's * not, then the user is trying to mess with us. */ if (((long)frame) & 3) goto badframe; 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); spin_lock_irq(¤t->sighand->siglock); current->blocked = set; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) goto badframe; if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT) goto badframe; return regs->r10; badframe: force_sig(SIGSEGV, current); return 0; } /* * Set up a signal frame. */ static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask) { int err = 0; unsigned long usp = rdusp(); /* copy the regs. they are first in sc so we can use sc directly */ err |= __copy_to_user(sc, regs, sizeof(struct pt_regs)); /* Set the frametype to CRIS_FRAME_NORMAL for the execution of the signal handler. The frametype will be restored to its previous value in restore_sigcontext. */ regs->frametype = CRIS_FRAME_NORMAL; /* then some other stuff */ err |= __put_user(mask, &sc->oldmask); err |= __put_user(usp, &sc->usp); return err; } /* figure out where we want to put the new signal frame - usually on the stack */ static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size) { unsigned long sp = rdusp(); /* This is the X/Open sanctioned signal stack switching. */ if (ka->sa.sa_flags & SA_ONSTACK) { if (! on_sig_stack(sp)) sp = current->sas_ss_sp + current->sas_ss_size; } /* make sure the frame is dword-aligned */ sp &= ~3; return (void __user*)(sp - frame_size); } /* grab and setup a signal frame. * * basically we stack a lot of state info, and arrange for the * user-mode program to return to the kernel using either a * trampoline which performs the syscall sigreturn, or a provided * user-mode trampoline. */ static void setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, struct pt_regs * regs) { struct sigframe __user *frame; unsigned long return_ip; int err = 0; frame = get_sigframe(ka, regs, sizeof(*frame)); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) goto give_sigsegv; err |= setup_sigcontext(&frame->sc, regs, set->sig[0]); if (err) goto give_sigsegv; if (_NSIG_WORDS > 1) { err |= __copy_to_user(frame->extramask, &set->sig[1], sizeof(frame->extramask)); } if (err) goto give_sigsegv; /* Set up to return from userspace. If provided, use a stub already in userspace. */ if (ka->sa.sa_flags & SA_RESTORER) { return_ip = (unsigned long)ka->sa.sa_restorer; } else { /* trampoline - the desired return ip is the retcode itself */ return_ip = (unsigned long)&frame->retcode; /* This is movu.w __NR_sigreturn, r9; break 13; */ err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0)); err |= __put_user(__NR_sigreturn, (short __user*)(frame->retcode+2)); err |= __put_user(0xe93d, (short __user*)(frame->retcode+4)); } if (err) goto give_sigsegv; /* Set up registers for signal handler */ regs->irp = (unsigned long) ka->sa.sa_handler; /* what we enter NOW */ regs->srp = return_ip; /* what we enter LATER */ regs->r10 = sig; /* first argument is signo */ /* actually move the usp to reflect the stacked frame */ wrusp((unsigned long)frame); return; give_sigsegv: force_sigsegv(sig, current); } static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs * regs) { struct rt_sigframe __user *frame; unsigned long return_ip; int err = 0; frame = get_sigframe(ka, regs, sizeof(*frame)); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) goto give_sigsegv; err |= __put_user(&frame->info, &frame->pinfo); err |= __put_user(&frame->uc, &frame->puc); err |= copy_siginfo_to_user(&frame->info, info); if (err) goto give_sigsegv; /* Clear all the bits of the ucontext we don't use. */ err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext)); err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]); 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. */ if (ka->sa.sa_flags & SA_RESTORER) { return_ip = (unsigned long)ka->sa.sa_restorer; } else { /* trampoline - the desired return ip is the retcode itself */ return_ip = (unsigned long)&frame->retcode; /* This is movu.w __NR_rt_sigreturn, r9; break 13; */ err |= __put_user(0x9c5f, (short __user*)(frame->retcode+0)); err |= __put_user(__NR_rt_sigreturn, (short __user*)(frame->retcode+2)); err |= __put_user(0xe93d, (short __user*)(frame->retcode+4)); } if (err) goto give_sigsegv; /* TODO what is the current->exec_domain stuff and invmap ? */ /* Set up registers for signal handler */ regs->irp = (unsigned long) ka->sa.sa_handler; /* what we enter NOW */ regs->srp = return_ip; /* what we enter LATER */ regs->r10 = sig; /* first argument is signo */ regs->r11 = (unsigned long) &frame->info; /* second argument is (siginfo_t *) */ regs->r12 = 0; /* third argument is unused */ /* actually move the usp to reflect the stacked frame */ wrusp((unsigned long)frame); return; give_sigsegv: force_sigsegv(sig, current); } /* * OK, we're invoking a handler */ static inline void handle_signal(int canrestart, unsigned long sig, siginfo_t *info, struct k_sigaction *ka, sigset_t *oldset, struct pt_regs * regs) { /* Are we from a system call? */ if (canrestart) { /* If so, check system call restarting.. */ switch (regs->r10) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: /* ERESTARTNOHAND means that the syscall should only be restarted if there was no handler for the signal, and since we only get here if there is a handler, we don't restart */ regs->r10 = -EINTR; break; case -ERESTARTSYS: /* ERESTARTSYS means to restart the syscall if there is no handler or the handler was registered with SA_RESTART */ if (!(ka->sa.sa_flags & SA_RESTART)) { regs->r10 = -EINTR; break; } /* fallthrough */ case -ERESTARTNOINTR: /* ERESTARTNOINTR means that the syscall should be called again after the signal handler returns. */ RESTART_CRIS_SYS(regs); } } /* 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; spin_lock_irq(¤t->sighand->siglock); sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); if (!(ka->sa.sa_flags & SA_NODEFER)) sigaddset(¤t->blocked,sig); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); } /* * 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. * * Also note that the regs structure given here as an argument, is the latest * pushed pt_regs. It may or may not be the same as the first pushed registers * when the initial usermode->kernelmode transition took place. Therefore * we can use user_mode(regs) to see if we came directly from kernel or user * mode below. */ int do_signal(int canrestart, sigset_t *oldset, struct pt_regs *regs) { siginfo_t info; int signr; struct k_sigaction ka; /* * We want the common case to go fast, which * is why we may in certain cases get here from * kernel mode. Just return without doing anything * if so. */ if (!user_mode(regs)) return 1; if (!oldset) oldset = ¤t->blocked; signr = get_signal_to_deliver(&info, &ka, regs, NULL); if (signr > 0) { /* Whee! Actually deliver the signal. */ handle_signal(canrestart, signr, &info, &ka, oldset, regs); return 1; } /* Did we come from a system call? */ if (canrestart) { /* Restart the system call - no handlers present */ if (regs->r10 == -ERESTARTNOHAND || regs->r10 == -ERESTARTSYS || regs->r10 == -ERESTARTNOINTR) { RESTART_CRIS_SYS(regs); } if (regs->r10 == -ERESTART_RESTARTBLOCK){ regs->r10 = __NR_restart_syscall; regs->irp -= 2; } } return 0; }