signal_32.c

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/*
 *  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/io.h>
#include <linux/tracehook.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>

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)
{
    sigset_t blocked;
    siginitset(&blocked, mask);
    return sigsuspend(&blocked);
}

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) ||
            __get_user(new_ka.sa.sa_flags, &act->sa_flags) ||
            __get_user(mask, &act->sa_mask))
            return -EFAULT;
        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) ||
            __put_user(old_ka.sa.sa_flags, &oact->sa_flags) ||
            __put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask))
            return -EFAULT;
    }

    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.xstate->hardfpu, &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())
        return __put_user(0, &sc->sc_ownedfp);

    if (__put_user(1, &sc->sc_ownedfp))
        return -EFAULT;

    /* 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.xstate->hardfpu,
                  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();
        err |= __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;

    set_current_blocked(&set);

    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;

    set_current_blocked(&set);

    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;

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

    if (err)
        goto give_sigsegv;

    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;

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

    if (err)
        goto give_sigsegv;

    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(__raw_readw(regs->pc - 4));
            break;
    }
}

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

    /*
     * 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) {
        handle_syscall_restart(save_r0, regs, &ka.sa);

        /* Whee!  Actually deliver the signal.  */
        handle_signal(signr, &ka, &info, regs, save_r0);
        return;
    }

    /* 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(__raw_readw(regs->pc - 4));
        } else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
            regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
            regs->regs[3] = __NR_restart_syscall;
        }
    }

    /*
     * If there's no signal to deliver, we just put the saved sigmask
     * back.
     */
    restore_saved_sigmask();
}

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);
    }
}