/* * Copyright (C) 2003, Axis Communications AB. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include extern unsigned long cris_signal_return_page; /* Flag to check if a signal is blockable. */ #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) /* * A syscall in CRIS is really a "break 13" instruction, which is 2 * bytes. The registers is manipulated so upon return the instruction * will be executed again. * * This relies on that PC points to the instruction after the break call. */ #define RESTART_CRIS_SYS(regs) regs->r10 = regs->orig_r10; regs->erp -= 2; /* Signal frames. */ struct signal_frame { struct sigcontext sc; unsigned long extramask[_NSIG_WORDS - 1]; unsigned char retcode[8]; /* Trampoline code. */ }; struct rt_signal_frame { struct siginfo *pinfo; void *puc; struct siginfo info; struct ucontext uc; unsigned char retcode[8]; /* Trampoline code. */ }; void do_signal(int restart, struct pt_regs *regs); void keep_debug_flags(unsigned long oldccs, unsigned long oldspc, struct pt_regs *regs); /* * Swap in the new signal mask, and wait for a signal. Define some * dummy arguments to be able to reach the regs argument. */ int sys_sigsuspend(old_sigset_t mask) { sigset_t blocked; siginitset(&blocked, mask); return sigsuspend(&blocked); } int sys_sigaction(int signal, const struct old_sigaction *act, struct old_sigaction *oact) { int retval; struct k_sigaction newk; struct k_sigaction oldk; if (act) { old_sigset_t mask; if (!access_ok(VERIFY_READ, act, sizeof(*act)) || __get_user(newk.sa.sa_handler, &act->sa_handler) || __get_user(newk.sa.sa_restorer, &act->sa_restorer) || __get_user(newk.sa.sa_flags, &act->sa_flags) || __get_user(mask, &act->sa_mask)) return -EFAULT; siginitset(&newk.sa.sa_mask, mask); } retval = do_sigaction(signal, act ? &newk : NULL, oact ? &oldk : NULL); if (!retval && oact) { if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) || __put_user(oldk.sa.sa_handler, &oact->sa_handler) || __put_user(oldk.sa.sa_restorer, &oact->sa_restorer) || __put_user(oldk.sa.sa_flags, &oact->sa_flags) || __put_user(oldk.sa.sa_mask.sig[0], &oact->sa_mask)) return -EFAULT; } return retval; } int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss) { return do_sigaltstack(uss, uoss, rdusp()); } 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 registers from &sc->regs. sc is already checked * for VERIFY_READ since the signal_frame was previously * checked in sys_sigreturn(). */ if (__copy_from_user(regs, sc, sizeof(struct pt_regs))) goto badframe; /* Make that the user-mode flag is set. */ regs->ccs |= (1 << (U_CCS_BITNR + CCS_SHIFT)); /* Restore the old USP. */ err |= __get_user(old_usp, &sc->usp); wrusp(old_usp); return err; badframe: return 1; } /* Define some 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) { sigset_t set; struct signal_frame __user *frame; unsigned long oldspc = regs->spc; unsigned long oldccs = regs->ccs; frame = (struct signal_frame *) rdusp(); /* * Since the signal is stacked on a dword boundary, the frame * should be dword aligned here as well. It it's not, then the * user is trying some funny business. */ 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); set_current_blocked(&set); if (restore_sigcontext(regs, &frame->sc)) goto badframe; keep_debug_flags(oldccs, oldspc, regs); return regs->r10; badframe: force_sig(SIGSEGV, current); return 0; } /* Define some dummy variables 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) { sigset_t set; struct rt_signal_frame __user *frame; unsigned long oldspc = regs->spc; unsigned long oldccs = regs->ccs; frame = (struct rt_signal_frame *) rdusp(); /* * Since the signal is stacked on a dword boundary, the frame * should be dword aligned here as well. It it's not, then the * user is trying some funny business. */ 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); set_current_blocked(&set); if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) goto badframe; if (do_sigaltstack(&frame->uc.uc_stack, NULL, rdusp()) == -EFAULT) goto badframe; keep_debug_flags(oldccs, oldspc, regs); return regs->r10; badframe: force_sig(SIGSEGV, current); return 0; } /* Setup a signal frame. */ static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask) { int err; unsigned long usp; err = 0; usp = rdusp(); /* * Copy the registers. They are located first in sc, so it's * possible to use sc directly. */ err |= __copy_to_user(sc, regs, sizeof(struct pt_regs)); err |= __put_user(mask, &sc->oldmask); err |= __put_user(usp, &sc->usp); return err; } /* Figure out where 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; 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 a lot of state-info is stacked, and arranged for the * user-mode program to return to the kernel using either a trampiline * which performs the syscall sigreturn(), or a provided user-mode * trampoline. */ static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, struct pt_regs * regs) { int err; unsigned long return_ip; struct signal_frame __user *frame; 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 user-space. If provided, use a stub * already located in user-space. */ if (ka->sa.sa_flags & SA_RESTORER) { return_ip = (unsigned long)ka->sa.sa_restorer; } else { /* Trampoline - the desired return ip is in the signal return page. */ return_ip = cris_signal_return_page; /* * This is movu.w __NR_sigreturn, r9; break 13; * * WE DO NOT USE IT ANY MORE! It's only left here for historical * reasons and because gdb uses it as a signature to notice * signal handler stack frames. */ 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. * * Where the code enters now. * Where the code enter later. * First argument, signo. */ regs->erp = (unsigned long) ka->sa.sa_handler; regs->srp = return_ip; regs->r10 = sig; /* Actually move the USP to reflect the stacked frame. */ wrusp((unsigned long)frame); return 0; give_sigsegv: force_sigsegv(sig, current); return -EFAULT; } static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs * regs) { int err; unsigned long return_ip; struct rt_signal_frame __user *frame; err = 0; frame = get_sigframe(ka, regs, sizeof(*frame)); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) goto give_sigsegv; /* TODO: what is the current->exec_domain stuff and invmap ? */ 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 user-space. If provided, use a stub * already located in user-space. */ if (ka->sa.sa_flags & SA_RESTORER) { return_ip = (unsigned long) ka->sa.sa_restorer; } else { /* Trampoline - the desired return ip is in the signal return page. */ return_ip = cris_signal_return_page + 6; /* * This is movu.w __NR_rt_sigreturn, r9; break 13; * * WE DO NOT USE IT ANY MORE! It's only left here for historical * reasons and because gdb uses it as a signature to notice * signal handler stack frames. */ 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; /* * Set up registers for signal handler. * * Where the code enters now. * Where the code enters later. * First argument is signo. * Second argument is (siginfo_t *). * Third argument is unused. */ regs->erp = (unsigned long) ka->sa.sa_handler; regs->srp = return_ip; regs->r10 = sig; regs->r11 = (unsigned long) &frame->info; regs->r12 = 0; /* Actually move the usp to reflect the stacked frame. */ wrusp((unsigned long)frame); return 0; give_sigsegv: force_sigsegv(sig, current); return -EFAULT; } /* Invoke a signal handler to, well, handle the signal. */ static inline int handle_signal(int canrestart, unsigned long sig, siginfo_t *info, struct k_sigaction *ka, struct pt_regs * regs) { sigset_t *oldset = sigmask_to_save(); int ret; /* Check if this got called from a system call. */ if (canrestart) { /* If so, check system call restarting. */ switch (regs->r10) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: /* * This means that the syscall should * only be restarted if there was no * handler for the signal, and since * this point isn't reached unless * there is a handler, there's no need * to restart. */ regs->r10 = -EINTR; break; case -ERESTARTSYS: /* * This means 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; } /* Fall through. */ case -ERESTARTNOINTR: /* * This means that the syscall should * be called again after the signal * handler returns. */ RESTART_CRIS_SYS(regs); break; } } /* Set up the stack frame. */ if (ka->sa.sa_flags & SA_SIGINFO) ret = setup_rt_frame(sig, ka, info, oldset, regs); else ret = setup_frame(sig, ka, oldset, regs); if (ret == 0) block_sigmask(ka, sig); return ret; } /* * 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. */ void do_signal(int canrestart, struct pt_regs *regs) { int signr; siginfo_t info; struct k_sigaction ka; /* * The common case should go fast, which is why this point is * reached from kernel-mode. If that's the case, just return * without doing anything. */ if (!user_mode(regs)) return; signr = get_signal_to_deliver(&info, &ka, regs, NULL); if (signr > 0) { /* Whee! Actually deliver the signal. */ if (handle_signal(canrestart, signr, &info, &ka, regs)) { /* a signal was successfully delivered; the saved * sigmask will have been stored in the signal frame, * and will be restored by sigreturn, so we can simply * clear the TIF_RESTORE_SIGMASK flag */ if (test_thread_flag(TIF_RESTORE_SIGMASK)) clear_thread_flag(TIF_RESTORE_SIGMASK); } return; } /* Got here 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->r9 = __NR_restart_syscall; regs->erp -= 2; } } /* if there's no signal to deliver, we just put the saved sigmask * back */ restore_saved_sigmask(); } asmlinkage void ugdb_trap_user(struct thread_info *ti, int sig) { if (((user_regs(ti)->exs & 0xff00) >> 8) != SINGLE_STEP_INTR_VECT) { /* Zero single-step PC if the reason we stopped wasn't a single step exception. This is to avoid relying on it when it isn't reliable. */ user_regs(ti)->spc = 0; } /* FIXME: Filter out false h/w breakpoint hits (i.e. EDA not within any configured h/w breakpoint range). Synchronize with what already exists for kernel debugging. */ if (((user_regs(ti)->exs & 0xff00) >> 8) == BREAK_8_INTR_VECT) { /* Break 8: subtract 2 from ERP unless in a delay slot. */ if (!(user_regs(ti)->erp & 0x1)) user_regs(ti)->erp -= 2; } sys_kill(ti->task->pid, sig); } void keep_debug_flags(unsigned long oldccs, unsigned long oldspc, struct pt_regs *regs) { if (oldccs & (1 << Q_CCS_BITNR)) { /* Pending single step due to single-stepping the break 13 in the signal trampoline: keep the Q flag. */ regs->ccs |= (1 << Q_CCS_BITNR); /* S flag should be set - complain if it's not. */ if (!(oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT)))) { printk("Q flag but no S flag?"); } regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT)); /* Assume the SPC is valid and interesting. */ regs->spc = oldspc; } else if (oldccs & (1 << (S_CCS_BITNR + CCS_SHIFT))) { /* If a h/w bp was set in the signal handler we need to keep the S flag. */ regs->ccs |= (1 << (S_CCS_BITNR + CCS_SHIFT)); /* Don't keep the old SPC though; if we got here due to a single-step, the Q flag should have been set. */ } else if (regs->spc) { /* If we were single-stepping *before* the signal was taken, we don't want to restore that state now, because GDB will have forgotten all about it. */ regs->spc = 0; regs->ccs &= ~(1 << (S_CCS_BITNR + CCS_SHIFT)); } } /* Set up the trampolines on the signal return page. */ int __init cris_init_signal(void) { u16* data = kmalloc(PAGE_SIZE, GFP_KERNEL); /* This is movu.w __NR_sigreturn, r9; break 13; */ data[0] = 0x9c5f; data[1] = __NR_sigreturn; data[2] = 0xe93d; /* This is movu.w __NR_rt_sigreturn, r9; break 13; */ data[3] = 0x9c5f; data[4] = __NR_rt_sigreturn; data[5] = 0xe93d; /* Map to userspace with appropriate permissions (no write access...) */ cris_signal_return_page = (unsigned long) __ioremap_prot(virt_to_phys(data), PAGE_SIZE, PAGE_SIGNAL_TRAMPOLINE); return 0; } __initcall(cris_init_signal);