diff options
Diffstat (limited to 'arch/openrisc/kernel/signal.c')
| -rw-r--r-- | arch/openrisc/kernel/signal.c | 396 |
1 files changed, 396 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/signal.c b/arch/openrisc/kernel/signal.c new file mode 100644 index 00000000000..5f759c76834 --- /dev/null +++ b/arch/openrisc/kernel/signal.c @@ -0,0 +1,396 @@ +/* + * 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 + +#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) + +asmlinkage long +_sys_sigaltstack(const stack_t *uss, stack_t *uoss, struct pt_regs *regs) +{ + return do_sigaltstack(uss, uoss, regs->sp); +} + +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; + unsigned long old_usp; + + /* 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 (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 SM-bit is cleared so user-mode cannot fool us */ + regs->sr &= ~SPR_SR_SM; + + /* 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); + + regs->sp = 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; +} + +asmlinkage long _sys_rt_sigreturn(struct pt_regs *regs) +{ + struct rt_sigframe *frame = (struct rt_sigframe __user *)regs->sp; + sigset_t set; + stack_t st; + + /* + * 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 (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st))) + goto badframe; + /* It is more difficult to avoid calling this function than to + call it and ignore errors. */ + do_sigaltstack(&st, NULL, regs->sp); + + 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; + unsigned long usp = regs->sp; + + /* copy the regs. they are first in sc so we can use sc directly */ + + err |= __copy_to_user(sc, regs, sizeof(struct pt_regs)); + + /* then some other stuff */ + + err |= __put_user(mask, &sc->oldmask); + + err |= __put_user(usp, &sc->usp); + + 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 void 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 |= __put_user((void *)current->sas_ss_sp, + &frame->uc.uc_stack.ss_sp); + err |= __put_user(sas_ss_flags(regs->sp), &frame->uc.uc_stack.ss_flags); + err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size); + 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; + +give_sigsegv: + if (sig == SIGSEGV) + ka->sa.sa_handler = SIG_DFL; + force_sig(SIGSEGV, current); +} + +static inline void +handle_signal(unsigned long sig, + siginfo_t *info, struct k_sigaction *ka, + sigset_t *oldset, struct pt_regs *regs) +{ + setup_rt_frame(sig, ka, info, 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. + */ + +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->syscallno) { + 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 */ + if (test_thread_flag(TIF_RESTORE_SIGMASK)) { + clear_thread_flag(TIF_RESTORE_SIGMASK); + sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); + } + + } else { /* signr > 0 */ + sigset_t *oldset; + + if (current_thread_info()->flags & _TIF_RESTORE_SIGMASK) + oldset = ¤t->saved_sigmask; + else + oldset = ¤t->blocked; + + /* Whee! Actually deliver the signal. */ + handle_signal(signr, &info, &ka, oldset, 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); + + tracehook_signal_handler(signr, &info, &ka, regs, + test_thread_flag(TIF_SINGLESTEP)); + } + + 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); + if (current->replacement_session_keyring) + key_replace_session_keyring(); + } +} |