/* * OpenRISC signal.c * * Linux architectural port borrowing liberally from similar works of * others. All original copyrights apply as per the original source * declaration. * * Modifications for the OpenRISC architecture: * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com> * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/sched.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/kernel.h> #include <linux/signal.h> #include <linux/errno.h> #include <linux/wait.h> #include <linux/ptrace.h> #include <linux/unistd.h> #include <linux/stddef.h> #include <linux/tracehook.h> #include <asm/processor.h> #include <asm/ucontext.h> #include <asm/uaccess.h> #define DEBUG_SIG 0 struct rt_sigframe { struct siginfo *pinfo; void *puc; struct siginfo info; struct ucontext uc; unsigned char retcode[16]; /* trampoline code */ }; static int restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc) { unsigned int err = 0; /* Alwys make any pending restarted system call return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; /* * Restore the regs from &sc->regs. * (sc is already checked for VERIFY_READ since the sigframe was * checked in sys_sigreturn previously) */ if (__copy_from_user(regs, sc->regs.gpr, 32 * sizeof(unsigned long))) goto badframe; if (__copy_from_user(®s->pc, &sc->regs.pc, sizeof(unsigned long))) goto badframe; if (__copy_from_user(®s->sr, &sc->regs.sr, sizeof(unsigned long))) goto badframe; /* make sure the SM-bit is cleared so user-mode cannot fool us */ regs->sr &= ~SPR_SR_SM; /* 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; } asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) { struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp; 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; set_current_blocked(&set); if (restore_sigcontext(regs, &frame->uc.uc_mcontext)) goto badframe; if (restore_altstack(&frame->uc.uc_stack)) goto badframe; return regs->gpr[11]; badframe: force_sig(SIGSEGV, current); return 0; } /* * Set up a signal frame. */ static int setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs, unsigned long mask) { int err = 0; /* copy the regs */ err |= __copy_to_user(sc->regs.gpr, regs, 32 * sizeof(unsigned long)); err |= __copy_to_user(&sc->regs.pc, ®s->pc, sizeof(unsigned long)); err |= __copy_to_user(&sc->regs.sr, ®s->sr, sizeof(unsigned long)); /* then some other stuff */ err |= __put_user(mask, &sc->oldmask); return err; } static inline unsigned long align_sigframe(unsigned long sp) { return sp & ~3UL; } /* * Work out where the signal frame should go. It's either on the user stack * or the alternate stack. */ static inline void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size) { unsigned long sp = regs->sp; int onsigstack = on_sig_stack(sp); /* redzone */ sp -= STACK_FRAME_OVERHEAD; /* This is the X/Open sanctioned signal stack switching. */ if ((ka->sa.sa_flags & SA_ONSTACK) && !onsigstack) { if (current->sas_ss_size) sp = current->sas_ss_sp + current->sas_ss_size; } sp = align_sigframe(sp - frame_size); /* * If we are on the alternate signal stack and would overflow it, don't. * Return an always-bogus address instead so we will die with SIGSEGV. */ if (onsigstack && !likely(on_sig_stack(sp))) return (void __user *)-1L; return (void __user *)sp; } /* 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 int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe *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); if (ka->sa.sa_flags & SA_SIGINFO) 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 |= __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(&frame->uc.uc_mcontext, regs, set->sig[0]); err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); if (err) goto give_sigsegv; /* 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 *)(frame->retcode + 0)); err |= __put_user(__NR_rt_sigreturn, (short *)(frame->retcode + 2)); err |= __put_user(0x20000001, (unsigned long *)(frame->retcode + 4)); err |= __put_user(0x15000000, (unsigned long *)(frame->retcode + 8)); if (err) goto give_sigsegv; /* TODO what is the current->exec_domain stuff and invmap ? */ /* Set up registers for signal handler */ regs->pc = (unsigned long)ka->sa.sa_handler; /* what we enter NOW */ regs->gpr[9] = (unsigned long)return_ip; /* what we enter LATER */ regs->gpr[3] = (unsigned long)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; give_sigsegv: force_sigsegv(sig, current); return -EFAULT; } static inline void handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, struct pt_regs *regs) { int ret; ret = setup_rt_frame(sig, ka, info, sigmask_to_save(), regs); if (ret) return; signal_delivered(sig, info, ka, regs, test_thread_flag(TIF_SINGLESTEP)); } /* * 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(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; signr = get_signal_to_deliver(&info, &ka, regs, NULL); /* If we are coming out of a syscall then we need * to check if the syscall was interrupted and wants to be * restarted after handling the signal. If so, the original * syscall number is put back into r11 and the PC rewound to * point at the l.sys instruction that resulted in the * original syscall. Syscall results other than the four * below mean that the syscall executed to completion and no * restart is necessary. */ if (regs->orig_gpr11) { int restart = 0; switch (regs->gpr[11]) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: /* Restart if there is no signal handler */ restart = (signr <= 0); break; case -ERESTARTSYS: /* Restart if there no signal handler or * SA_RESTART flag is set */ restart = (signr <= 0 || (ka.sa.sa_flags & SA_RESTART)); break; case -ERESTARTNOINTR: /* Always restart */ restart = 1; break; } if (restart) { if (regs->gpr[11] == -ERESTART_RESTARTBLOCK) regs->gpr[11] = __NR_restart_syscall; else regs->gpr[11] = regs->orig_gpr11; regs->pc -= 4; } else { regs->gpr[11] = -EINTR; } } if (signr <= 0) { /* no signal to deliver so we just put the saved sigmask * back */ restore_saved_sigmask(); } else { /* signr > 0 */ /* Whee! Actually deliver the signal. */ handle_signal(signr, &info, &ka, regs); } return; } asmlinkage void do_notify_resume(struct pt_regs *regs) { if (current_thread_info()->flags & _TIF_SIGPENDING) do_signal(regs); if (current_thread_info()->flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); } }