/*
 *  linux/arch/sh/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *
 *  SuperH version:  Copyright (C) 1999, 2000  Niibe Yutaka & Kaz Kojima
 *
 */
#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/tty.h>
#include <linux/elf.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/freezer.h>
#include <linux/io.h>
#include <linux/tracehook.h>
#include <asm/system.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/fpu.h>

#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))

struct fdpic_func_descriptor {
        unsigned long   text;
        unsigned long   GOT;
};

/*
 * The following define adds a 64 byte gap between the signal
 * stack frame and previous contents of the stack.  This allows
 * frame unwinding in a function epilogue but only if a frame
 * pointer is used in the function.  This is necessary because
 * current gcc compilers (<4.3) do not generate unwind info on
 * SH for function epilogues.
 */
#define UNWINDGUARD 64

/*
 * Atomically swap in the new signal mask, and wait for a signal.
 */
asmlinkage int
sys_sigsuspend(old_sigset_t mask,
               unsigned long r5, unsigned long r6, unsigned long r7,
               struct pt_regs __regs)
{
        mask &= _BLOCKABLE;
        spin_lock_irq(&current->sighand->siglock);
        current->saved_sigmask = current->blocked;
        siginitset(&current->blocked, mask);
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        current->state = TASK_INTERRUPTIBLE;
        schedule();
        set_thread_flag(TIF_RESTORE_SIGMASK);
        return -ERESTARTNOHAND;
}

asmlinkage int
sys_sigaction(int sig, const struct old_sigaction __user *act,
              struct old_sigaction __user *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;
}

asmlinkage int
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
                unsigned long r6, unsigned long r7,
                struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);

        return do_sigaltstack(uss, uoss, regs->regs[15]);
}


/*
 * Do a signal return; undo the signal stack.
 */

#define MOVW(n)  (0x9300|((n)-2))       /* Move mem word at PC+n to R3 */
#if defined(CONFIG_CPU_SH2)
#define TRAP_NOARG 0xc320               /* Syscall w/no args (NR in R3) */
#else
#define TRAP_NOARG 0xc310               /* Syscall w/no args (NR in R3) */
#endif
#define OR_R0_R0 0x200b                 /* or r0,r0 (insert to avoid hardware bug) */

struct sigframe
{
        struct sigcontext sc;
        unsigned long extramask[_NSIG_WORDS-1];
        u16 retcode[8];
};

struct rt_sigframe
{
        struct siginfo info;
        struct ucontext uc;
        u16 retcode[8];
};

#ifdef CONFIG_SH_FPU
static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
{
        struct task_struct *tsk = current;

        if (!(boot_cpu_data.flags & CPU_HAS_FPU))
                return 0;

        set_used_math();
        return __copy_from_user(&tsk->thread.fpu.hard, &sc->sc_fpregs[0],
                                sizeof(long)*(16*2+2));
}

static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
                                      struct pt_regs *regs)
{
        struct task_struct *tsk = current;

        if (!(boot_cpu_data.flags & CPU_HAS_FPU))
                return 0;

        if (!used_math()) {
                __put_user(0, &sc->sc_ownedfp);
                return 0;
        }

        __put_user(1, &sc->sc_ownedfp);

        /* This will cause a "finit" to be triggered by the next
           attempted FPU operation by the 'current' process.
           */
        clear_used_math();

        unlazy_fpu(tsk, regs);
        return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.fpu.hard,
                              sizeof(long)*(16*2+2));
}
#endif /* CONFIG_SH_FPU */

static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
{
        unsigned int err = 0;

#define COPY(x)         err |= __get_user(regs->x, &sc->sc_##x)
                        COPY(regs[1]);
        COPY(regs[2]);  COPY(regs[3]);
        COPY(regs[4]);  COPY(regs[5]);
        COPY(regs[6]);  COPY(regs[7]);
        COPY(regs[8]);  COPY(regs[9]);
        COPY(regs[10]); COPY(regs[11]);
        COPY(regs[12]); COPY(regs[13]);
        COPY(regs[14]); COPY(regs[15]);
        COPY(gbr);      COPY(mach);
        COPY(macl);     COPY(pr);
        COPY(sr);       COPY(pc);
#undef COPY

#ifdef CONFIG_SH_FPU
        if (boot_cpu_data.flags & CPU_HAS_FPU) {
                int owned_fp;
                struct task_struct *tsk = current;

                regs->sr |= SR_FD; /* Release FPU */
                clear_fpu(tsk, regs);
                clear_used_math();
                __get_user (owned_fp, &sc->sc_ownedfp);
                if (owned_fp)
                        err |= restore_sigcontext_fpu(sc);
        }
#endif

        regs->tra = -1;         /* disable syscall checks */
        err |= __get_user(*r0_p, &sc->sc_regs[0]);
        return err;
}

asmlinkage int sys_sigreturn(unsigned long r4, unsigned long r5,
                             unsigned long r6, unsigned long r7,
                             struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
        struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
        sigset_t set;
        int r0;

        /* Always make any pending restarted system calls return -EINTR */
        current_thread_info()->restart_block.fn = do_no_restart_syscall;

        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(&current->sighand->siglock);
        current->blocked = set;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        if (restore_sigcontext(regs, &frame->sc, &r0))
                goto badframe;
        return r0;

badframe:
        force_sig(SIGSEGV, current);
        return 0;
}

asmlinkage int sys_rt_sigreturn(unsigned long r4, unsigned long r5,
                                unsigned long r6, unsigned long r7,
                                struct pt_regs __regs)
{
        struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
        struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
        sigset_t set;
        int r0;

        /* Always make any pending restarted system calls return -EINTR */
        current_thread_info()->restart_block.fn = do_no_restart_syscall;

        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(&current->sighand->siglock);
        current->blocked = set;
        recalc_sigpending();
        spin_unlock_irq(&current->sighand->siglock);

        if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
                goto badframe;

        if (do_sigaltstack(&frame->uc.uc_stack, NULL,
                           regs->regs[15]) == -EFAULT)
                goto badframe;

        return r0;

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;

#define COPY(x)         err |= __put_user(regs->x, &sc->sc_##x)
        COPY(regs[0]);  COPY(regs[1]);
        COPY(regs[2]);  COPY(regs[3]);
        COPY(regs[4]);  COPY(regs[5]);
        COPY(regs[6]);  COPY(regs[7]);
        COPY(regs[8]);  COPY(regs[9]);
        COPY(regs[10]); COPY(regs[11]);
        COPY(regs[12]); COPY(regs[13]);
        COPY(regs[14]); COPY(regs[15]);
        COPY(gbr);      COPY(mach);
        COPY(macl);     COPY(pr);
        COPY(sr);       COPY(pc);
#undef COPY

#ifdef CONFIG_SH_FPU
        err |= save_sigcontext_fpu(sc, regs);
#endif

        /* non-iBCS2 extensions.. */
        err |= __put_user(mask, &sc->oldmask);

        return err;
}

/*
 * Determine which stack to use..
 */
static inline void __user *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
        if (ka->sa.sa_flags & SA_ONSTACK) {
                if (sas_ss_flags(sp) == 0)
                        sp = current->sas_ss_sp + current->sas_ss_size;
        }

        return (void __user *)((sp - (frame_size+UNWINDGUARD)) & -8ul);
}

/* These symbols are defined with the addresses in the vsyscall page.
   See vsyscall-trapa.S.  */
extern void __kernel_sigreturn(void);
extern void __kernel_rt_sigreturn(void);

static int setup_frame(int sig, struct k_sigaction *ka,
                        sigset_t *set, struct pt_regs *regs)
{
        struct sigframe __user *frame;
        int err = 0;
        int signal;

        frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));

        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
                goto give_sigsegv;

        signal = current_thread_info()->exec_domain
                && current_thread_info()->exec_domain->signal_invmap
                && sig < 32
                ? current_thread_info()->exec_domain->signal_invmap[sig]
                : sig;

        err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);

        if (_NSIG_WORDS > 1)
                err |= __copy_to_user(frame->extramask, &set->sig[1],
                                      sizeof(frame->extramask));

        /* Set up to return from userspace.  If provided, use a stub
           already in userspace.  */
        if (ka->sa.sa_flags & SA_RESTORER) {
                regs->pr = (unsigned long) ka->sa.sa_restorer;
#ifdef CONFIG_VSYSCALL
        } else if (likely(current->mm->context.vdso)) {
                regs->pr = VDSO_SYM(&__kernel_sigreturn);
#endif
        } else {
                /* Generate return code (system call to sigreturn) */
                err |= __put_user(MOVW(7), &frame->retcode[0]);
                err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
                err |= __put_user(OR_R0_R0, &frame->retcode[2]);
                err |= __put_user(OR_R0_R0, &frame->retcode[3]);
                err |= __put_user(OR_R0_R0, &frame->retcode[4]);
                err |= __put_user(OR_R0_R0, &frame->retcode[5]);
                err |= __put_user(OR_R0_R0, &frame->retcode[6]);
                err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
                regs->pr = (unsigned long) frame->retcode;
                flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
        }

        if (err)
                goto give_sigsegv;

        /* Set up registers for signal handler */
        regs->regs[15] = (unsigned long) frame;
        regs->regs[4] = signal; /* Arg for signal handler */
        regs->regs[5] = 0;
        regs->regs[6] = (unsigned long) &frame->sc;

        if (current->personality & FDPIC_FUNCPTRS) {
                struct fdpic_func_descriptor __user *funcptr =
                        (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;

                __get_user(regs->pc, &funcptr->text);
                __get_user(regs->regs[12], &funcptr->GOT);
        } else
                regs->pc = (unsigned long)ka->sa.sa_handler;

        set_fs(USER_DS);

        pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
                 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);

        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)
{
        struct rt_sigframe __user *frame;
        int err = 0;
        int signal;

        frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));

        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
                goto give_sigsegv;

        signal = current_thread_info()->exec_domain
                && current_thread_info()->exec_domain->signal_invmap
                && sig < 32
                ? current_thread_info()->exec_domain->signal_invmap[sig]
                : sig;

        err |= copy_siginfo_to_user(&frame->info, info);

        /* Create the ucontext.  */
        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->regs[15]),
                          &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));

        /* Set up to return from userspace.  If provided, use a stub
           already in userspace.  */
        if (ka->sa.sa_flags & SA_RESTORER) {
                regs->pr = (unsigned long) ka->sa.sa_restorer;
#ifdef CONFIG_VSYSCALL
        } else if (likely(current->mm->context.vdso)) {
                regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
#endif
        } else {
                /* Generate return code (system call to rt_sigreturn) */
                err |= __put_user(MOVW(7), &frame->retcode[0]);
                err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
                err |= __put_user(OR_R0_R0, &frame->retcode[2]);
                err |= __put_user(OR_R0_R0, &frame->retcode[3]);
                err |= __put_user(OR_R0_R0, &frame->retcode[4]);
                err |= __put_user(OR_R0_R0, &frame->retcode[5]);
                err |= __put_user(OR_R0_R0, &frame->retcode[6]);
                err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
                regs->pr = (unsigned long) frame->retcode;
                flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
        }

        if (err)
                goto give_sigsegv;

        /* Set up registers for signal handler */
        regs->regs[15] = (unsigned long) frame;
        regs->regs[4] = signal; /* Arg for signal handler */
        regs->regs[5] = (unsigned long) &frame->info;
        regs->regs[6] = (unsigned long) &frame->uc;

        if (current->personality & FDPIC_FUNCPTRS) {
                struct fdpic_func_descriptor __user *funcptr =
                        (struct fdpic_func_descriptor __user *)ka->sa.sa_handler;

                __get_user(regs->pc, &funcptr->text);
                __get_user(regs->regs[12], &funcptr->GOT);
        } else
                regs->pc = (unsigned long)ka->sa.sa_handler;

        set_fs(USER_DS);

        pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
                 current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);

        return 0;

give_sigsegv:
        force_sigsegv(sig, current);
        return -EFAULT;
}

static inline void
handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
                       struct sigaction *sa)
{
        /* If we're not from a syscall, bail out */
        if (regs->tra < 0)
                return;

        /* check for system call restart.. */
        switch (regs->regs[0]) {
                case -ERESTART_RESTARTBLOCK:
                case -ERESTARTNOHAND:
                no_system_call_restart:
                        regs->regs[0] = -EINTR;
                        break;

                case -ERESTARTSYS:
                        if (!(sa->sa_flags & SA_RESTART))
                                goto no_system_call_restart;
                /* fallthrough */
                case -ERESTARTNOINTR:
                        regs->regs[0] = save_r0;
                        regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
                        break;
        }
}

/*
 * OK, we're invoking a handler
 */
static int
handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
              sigset_t *oldset, struct pt_regs *regs, unsigned int save_r0)
{
        int ret;

        /* 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 (ka->sa.sa_flags & SA_ONESHOT)
                ka->sa.sa_handler = SIG_DFL;

        if (ret == 0) {
                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,sig);
                recalc_sigpending();
                spin_unlock_irq(&current->sighand->siglock);
        }

        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.
 *
 * Note that we go through the signals twice: once to check the signals that
 * the kernel can handle, and then we build all the user-level signal handling
 * stack-frames in one go after that.
 */
static void do_signal(struct pt_regs *regs, unsigned int save_r0)
{
        siginfo_t info;
        int signr;
        struct k_sigaction ka;
        sigset_t *oldset;

        /*
         * 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;

        if (try_to_freeze())
                goto no_signal;

        if (test_thread_flag(TIF_RESTORE_SIGMASK))
                oldset = &current->saved_sigmask;
        else
                oldset = &current->blocked;

        signr = get_signal_to_deliver(&info, &ka, regs, NULL);
        if (signr > 0) {
                handle_syscall_restart(save_r0, regs, &ka.sa);

                /* Whee!  Actually deliver the signal.  */
                if (handle_signal(signr, &ka, &info, oldset,
                                  regs, save_r0) == 0) {
                        /* 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;
        }

no_signal:
        /* Did we come from a system call? */
        if (regs->tra >= 0) {
                /* Restart the system call - no handlers present */
                if (regs->regs[0] == -ERESTARTNOHAND ||
                    regs->regs[0] == -ERESTARTSYS ||
                    regs->regs[0] == -ERESTARTNOINTR) {
                        regs->regs[0] = save_r0;
                        regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
                } else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
                        regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
                        regs->regs[3] = __NR_restart_syscall;
                }
        }

        /* if there's no signal to deliver, we just put the saved sigmask
         * back */
        if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
                clear_thread_flag(TIF_RESTORE_SIGMASK);
                sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
        }
}

asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
                                 unsigned long thread_info_flags)
{
        /* deal with pending signal delivery */
        if (thread_info_flags & _TIF_SIGPENDING)
                do_signal(regs, save_r0);

        if (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();
        }
}