signal.c

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/*
 *  linux/arch/m32r/kernel/signal.c
 *
 *  Copyright (c) 2003  Hitoshi Yamamoto
 *
 *  Taken from i386 version.
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
 *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
 */

#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/unistd.h>
#include <linux/stddef.h>
#include <linux/personality.h>
#include <linux/tracehook.h>
#include <asm/cacheflush.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>

#define DEBUG_SIG 0

asmlinkage int
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
        unsigned long r2, unsigned long r3, unsigned long r4,
        unsigned long r5, unsigned long r6, struct pt_regs *regs)
{
    return do_sigaltstack(uss, uoss, regs->spu);
}


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

struct rt_sigframe
{
    int sig;
    struct siginfo __user *pinfo;
    void __user *puc;
    struct siginfo info;
    struct ucontext uc;
//  struct _fpstate fpstate;
};

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

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

#define COPY(x)     err |= __get_user(regs->x, &sc->sc_##x)
    COPY(r4);
    COPY(r5);
    COPY(r6);
    COPY(pt_regs);
    /* COPY(r0); Skip r0 */
    COPY(r1);
    COPY(r2);
    COPY(r3);
    COPY(r7);
    COPY(r8);
    COPY(r9);
    COPY(r10);
    COPY(r11);
    COPY(r12);
    COPY(acc0h);
    COPY(acc0l);
    COPY(acc1h);        /* ISA_DSP_LEVEL2 only */
    COPY(acc1l);        /* ISA_DSP_LEVEL2 only */
    COPY(psw);
    COPY(bpc);
    COPY(bbpsw);
    COPY(bbpc);
    COPY(spu);
    COPY(fp);
    COPY(lr);
    COPY(spi);
#undef COPY

    regs->syscall_nr = -1;  /* disable syscall checks */
    err |= __get_user(*r0_p, &sc->sc_r0);

    return err;
}

asmlinkage int
sys_rt_sigreturn(unsigned long r0, unsigned long r1,
         unsigned long r2, unsigned long r3, unsigned long r4,
         unsigned long r5, unsigned long r6, struct pt_regs *regs)
{
    struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->spu;
    sigset_t set;
    int result;

    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, &result))
        goto badframe;

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

    return result;

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(r4);
    COPY(r5);
    COPY(r6);
    COPY(pt_regs);
    COPY(r0);
    COPY(r1);
    COPY(r2);
    COPY(r3);
    COPY(r7);
    COPY(r8);
    COPY(r9);
    COPY(r10);
    COPY(r11);
    COPY(r12);
    COPY(acc0h);
    COPY(acc0l);
    COPY(acc1h);        /* ISA_DSP_LEVEL2 only */
    COPY(acc1l);        /* ISA_DSP_LEVEL2 only */
    COPY(psw);
    COPY(bpc);
    COPY(bbpsw);
    COPY(bbpc);
    COPY(spu);
    COPY(fp);
    COPY(lr);
    COPY(spi);
#undef COPY

    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)
{
    /* This is the X/Open sanctioned signal stack switching.  */
    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) & -8ul);
}

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->spu, 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 |= __put_user(signal, &frame->sig);
    if (err)
        goto give_sigsegv;

    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;

    /* Create the ucontext.  */
    err |= __put_user(0, &frame->uc.uc_flags);
    err |= __put_user(0, &frame->uc.uc_link);
    err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
    err |= __put_user(sas_ss_flags(regs->spu),
              &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;

    /* Set up to return from userspace.  */
    regs->lr = (unsigned long)ka->sa.sa_restorer;

    /* Set up registers for signal handler */
    regs->spu = (unsigned long)frame;
    regs->r0 = signal;  /* Arg for signal handler */
    regs->r1 = (unsigned long)&frame->info;
    regs->r2 = (unsigned long)&frame->uc;
    regs->bpc = (unsigned long)ka->sa.sa_handler;

    set_fs(USER_DS);

#if DEBUG_SIG
    printk("SIG deliver (%s:%d): sp=%p pc=%p\n",
        current->comm, current->pid, frame, regs->pc);
#endif

    return 0;

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

static int prev_insn(struct pt_regs *regs)
{
    u16 inst;
    if (get_user(inst, (u16 __user *)(regs->bpc - 2)))
        return -EFAULT;
    if ((inst & 0xfff0) == 0x10f0)  /* trap ? */
        regs->bpc -= 2;
    else
        regs->bpc -= 4;
    regs->syscall_nr = -1;
    return 0;
}

/*
 * OK, we're invoking a handler
 */

static void
handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
          struct pt_regs *regs)
{
    /* Are we from a system call? */
    if (regs->syscall_nr >= 0) {
        /* If so, check system call restarting.. */
        switch (regs->r0) {
                case -ERESTART_RESTARTBLOCK:
            case -ERESTARTNOHAND:
                regs->r0 = -EINTR;
                break;

            case -ERESTARTSYS:
                if (!(ka->sa.sa_flags & SA_RESTART)) {
                    regs->r0 = -EINTR;
                    break;
                }
            /* fallthrough */
            case -ERESTARTNOINTR:
                regs->r0 = regs->orig_r0;
                if (prev_insn(regs) < 0)
                    return;
        }
    }

    /* Set up the stack frame */
    if (setup_rt_frame(sig, ka, info, sigmask_to_save(), regs))
        return;

    signal_delivered(sig, info, ka, regs, 0);
}

/*
 * 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.
 */
static 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 (signr > 0) {
        /* Re-enable any watchpoints before delivering the
         * signal to user space. The processor register will
         * have been cleared if the watchpoint triggered
         * inside the kernel.
         */

        /* Whee!  Actually deliver the signal.  */
        handle_signal(signr, &ka, &info, regs);

        return;
    }

    /* Did we come from a system call? */
    if (regs->syscall_nr >= 0) {
        /* Restart the system call - no handlers present */
        if (regs->r0 == -ERESTARTNOHAND ||
            regs->r0 == -ERESTARTSYS ||
            regs->r0 == -ERESTARTNOINTR) {
            regs->r0 = regs->orig_r0;
            prev_insn(regs);
        } else if (regs->r0 == -ERESTART_RESTARTBLOCK){
            regs->r0 = regs->orig_r0;
            regs->r7 = __NR_restart_syscall;
            prev_insn(regs);
        }
    }
    restore_saved_sigmask();
}

/*
 * notification of userspace execution resumption
 * - triggered by current->work.notify_resume
 */
void do_notify_resume(struct pt_regs *regs, __u32 thread_info_flags)
{
    /* Pending single-step? */
    if (thread_info_flags & _TIF_SINGLESTEP)
        clear_thread_flag(TIF_SINGLESTEP);

    /* deal with pending signal delivery */
    if (thread_info_flags & _TIF_SIGPENDING)
        do_signal(regs);

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