/*
 * Common signal handling code for both 32 and 64 bits
 *
 *    Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
 *    Extracted from signal_32.c and signal_64.c
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file README.legal in the main directory of
 * this archive for more details.
 */

#include <linux/tracehook.h>
#include <linux/signal.h>
#include <asm/hw_breakpoint.h>
#include <asm/uaccess.h>
#include <asm/unistd.h>

#include "signal.h"

/* Log an error when sending an unhandled signal to a process. Controlled
 * through debug.exception-trace sysctl.
 */

int show_unhandled_signals = 0;

/*
 * Allocate space for the signal frame
 */
void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
                           size_t frame_size, int is_32)
{
        unsigned long oldsp, newsp;

        /* Default to using normal stack */
        oldsp = get_clean_sp(regs, is_32);

        /* Check for alt stack */
        if ((ka->sa.sa_flags & SA_ONSTACK) &&
            current->sas_ss_size && !on_sig_stack(oldsp))
                oldsp = (current->sas_ss_sp + current->sas_ss_size);

        /* Get aligned frame */
        newsp = (oldsp - frame_size) & ~0xFUL;

        /* Check access */
        if (!access_ok(VERIFY_WRITE, (void __user *)newsp, oldsp - newsp))
                return NULL;

        return (void __user *)newsp;
}


/*
 * Restore the user process's signal mask
 */
void restore_sigmask(sigset_t *set)
{
        sigdelsetmask(set, ~_BLOCKABLE);
        spin_lock_irq(&current->sighand->siglock);
        current->blocked = *set;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);
}

static void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
                                  int has_handler)
{
        unsigned long ret = regs->gpr[3];
        int restart = 1;

        /* syscall ? */
        if (TRAP(regs) != 0x0C00)
                return;

        /* error signalled ? */
        if (!(regs->ccr & 0x10000000))
                return;

        switch (ret) {
        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 dont restart.
                 */
                restart = !has_handler;
                break;
        case ERESTARTSYS:
                /* ERESTARTSYS means to restart the syscall if there is no
                 * handler or the handler was registered with SA_RESTART
                 */
                restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
                break;
        case ERESTARTNOINTR:
                /* ERESTARTNOINTR means that the syscall should be
                 * called again after the signal handler returns.
                 */
                break;
        default:
                return;
        }
        if (restart) {
                if (ret == ERESTART_RESTARTBLOCK)
                        regs->gpr[0] = __NR_restart_syscall;
                else
                        regs->gpr[3] = regs->orig_gpr3;
                regs->nip -= 4;
                regs->result = 0;
        } else {
                regs->result = -EINTR;
                regs->gpr[3] = EINTR;
                regs->ccr |= 0x10000000;
        }
}

static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
{
        siginfo_t info;
        int signr;
        struct k_sigaction ka;
        int ret;
        int is32 = is_32bit_task();

        if (current_thread_info()->local_flags & _TLF_RESTORE_SIGMASK)
                oldset = &current->saved_sigmask;
        else if (!oldset)
                oldset = &current->blocked;

        signr = get_signal_to_deliver(&info, &ka, regs, NULL);

        /* Is there any syscall restart business here ? */
        check_syscall_restart(regs, &ka, signr > 0);

        if (signr <= 0) {
                struct thread_info *ti = current_thread_info();
                /* No signal to deliver -- put the saved sigmask back */
                if (ti->local_flags & _TLF_RESTORE_SIGMASK) {
                        ti->local_flags &= ~_TLF_RESTORE_SIGMASK;
                        sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
                }
                regs->trap = 0;
                return 0;               /* no signals delivered */
        }

#ifndef CONFIG_PPC_ADV_DEBUG_REGS
        /*
         * Reenable the DABR before delivering the signal to
         * user space. The DABR will have been cleared if it
         * triggered inside the kernel.
         */
        if (current->thread.dabr)
                set_dabr(current->thread.dabr);
#endif
        /* Re-enable the breakpoints for the signal stack */
        thread_change_pc(current, regs);

        if (is32) {
                if (ka.sa.sa_flags & SA_SIGINFO)
                        ret = handle_rt_signal32(signr, &ka, &info, oldset,
                                        regs);
                else
                        ret = handle_signal32(signr, &ka, &info, oldset,
                                        regs);
        } else {
                ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
        }

        regs->trap = 0;
        if (ret) {
                spin_lock_irq(&current->sighand->siglock);
                sigorsets(&current->blocked, &current->blocked,
                          &ka.sa.sa_mask);
                if (!(ka.sa.sa_flags & SA_NODEFER))
                        sigaddset(&current->blocked, signr);
                recalc_sigpending();
                spin_unlock_irq(&current->sighand->siglock);

                /*
                 * A signal was successfully delivered; the saved sigmask is in
                 * its frame, and we can clear the TLF_RESTORE_SIGMASK flag.
                 */
                current_thread_info()->local_flags &= ~_TLF_RESTORE_SIGMASK;

                /*
                 * Let tracing know that we've done the handler setup.
                 */
                tracehook_signal_handler(signr, &info, &ka, regs,
                                         test_thread_flag(TIF_SINGLESTEP));
        }

        return ret;
}

void do_signal(struct pt_regs *regs, unsigned long thread_info_flags)
{
        if (thread_info_flags & _TIF_SIGPENDING)
                do_signal_pending(NULL, regs);

        if (thread_info_flags & _TIF_NOTIFY_RESUME) {
                clear_thread_flag(TIF_NOTIFY_RESUME);
                tracehook_notify_resume(regs);
        }
}

long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
                unsigned long r5, unsigned long r6, unsigned long r7,
                unsigned long r8, struct pt_regs *regs)
{
        return do_sigaltstack(uss, uoss, regs->gpr[1]);
}