signal_32.c

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/*  linux/arch/sparc/kernel/signal.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1995 David S. Miller ([email protected])
 *  Copyright (C) 1996 Miguel de Icaza ([email protected])
 *  Copyright (C) 1997 Eddie C. Dost   ([email protected])
 */

#include <linux/sched.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/mm.h>
#include <linux/tty.h>
#include <linux/smp.h>
#include <linux/binfmts.h>  /* do_coredum */
#include <linux/bitops.h>
#include <linux/tracehook.h>

#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h> /* flush_sig_insns */
#include <asm/switch_to.h>

#include "sigutil.h"

extern void fpsave(unsigned long *fpregs, unsigned long *fsr,
           void *fpqueue, unsigned long *fpqdepth);
extern void fpload(unsigned long *fpregs, unsigned long *fsr);

struct signal_frame {
    struct sparc_stackf ss;
    __siginfo32_t       info;
    __siginfo_fpu_t __user  *fpu_save;
    unsigned long       insns[2] __attribute__ ((aligned (8)));
    unsigned int        extramask[_NSIG_WORDS - 1];
    unsigned int        extra_size; /* Should be 0 */
    __siginfo_rwin_t __user *rwin_save;
} __attribute__((aligned(8)));

struct rt_signal_frame {
    struct sparc_stackf ss;
    siginfo_t       info;
    struct pt_regs      regs;
    sigset_t        mask;
    __siginfo_fpu_t __user  *fpu_save;
    unsigned int        insns[2];
    stack_t         stack;
    unsigned int        extra_size; /* Should be 0 */
    __siginfo_rwin_t __user *rwin_save;
} __attribute__((aligned(8)));

/* Align macros */
#define SF_ALIGNEDSZ  (((sizeof(struct signal_frame) + 7) & (~7)))
#define RT_ALIGNEDSZ  (((sizeof(struct rt_signal_frame) + 7) & (~7)))

static int _sigpause_common(old_sigset_t set)
{
    sigset_t blocked;
    siginitset(&blocked, set);
    return sigsuspend(&blocked);
}

asmlinkage int sys_sigsuspend(old_sigset_t set)
{
    return _sigpause_common(set);
}

asmlinkage void do_sigreturn(struct pt_regs *regs)
{
    struct signal_frame __user *sf;
    unsigned long up_psr, pc, npc;
    sigset_t set;
    __siginfo_fpu_t __user *fpu_save;
    __siginfo_rwin_t __user *rwin_save;
    int err;

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

    synchronize_user_stack();

    sf = (struct signal_frame __user *) regs->u_regs[UREG_FP];

    /* 1. Make sure we are not getting garbage from the user */
    if (!access_ok(VERIFY_READ, sf, sizeof(*sf)))
        goto segv_and_exit;

    if (((unsigned long) sf) & 3)
        goto segv_and_exit;

    err = __get_user(pc,  &sf->info.si_regs.pc);
    err |= __get_user(npc, &sf->info.si_regs.npc);

    if ((pc | npc) & 3)
        goto segv_and_exit;

    /* 2. Restore the state */
    up_psr = regs->psr;
    err |= __copy_from_user(regs, &sf->info.si_regs, sizeof(struct pt_regs));

    /* User can only change condition codes and FPU enabling in %psr. */
    regs->psr = (up_psr & ~(PSR_ICC | PSR_EF))
          | (regs->psr & (PSR_ICC | PSR_EF));

    /* Prevent syscall restart.  */
    pt_regs_clear_syscall(regs);

    err |= __get_user(fpu_save, &sf->fpu_save);
    if (fpu_save)
        err |= restore_fpu_state(regs, fpu_save);
    err |= __get_user(rwin_save, &sf->rwin_save);
    if (rwin_save)
        err |= restore_rwin_state(rwin_save);

    /* This is pretty much atomic, no amount locking would prevent
     * the races which exist anyways.
     */
    err |= __get_user(set.sig[0], &sf->info.si_mask);
    err |= __copy_from_user(&set.sig[1], &sf->extramask,
                    (_NSIG_WORDS-1) * sizeof(unsigned int));
               
    if (err)
        goto segv_and_exit;

    set_current_blocked(&set);
    return;

segv_and_exit:
    force_sig(SIGSEGV, current);
}

asmlinkage void do_rt_sigreturn(struct pt_regs *regs)
{
    struct rt_signal_frame __user *sf;
    unsigned int psr, pc, npc;
    __siginfo_fpu_t __user *fpu_save;
    __siginfo_rwin_t __user *rwin_save;
    mm_segment_t old_fs;
    sigset_t set;
    stack_t st;
    int err;

    synchronize_user_stack();
    sf = (struct rt_signal_frame __user *) regs->u_regs[UREG_FP];
    if (!access_ok(VERIFY_READ, sf, sizeof(*sf)) ||
        (((unsigned long) sf) & 0x03))
        goto segv;

    err = __get_user(pc, &sf->regs.pc);
    err |= __get_user(npc, &sf->regs.npc);
    err |= ((pc | npc) & 0x03);

    err |= __get_user(regs->y, &sf->regs.y);
    err |= __get_user(psr, &sf->regs.psr);

    err |= __copy_from_user(&regs->u_regs[UREG_G1],
                &sf->regs.u_regs[UREG_G1], 15 * sizeof(u32));

    regs->psr = (regs->psr & ~PSR_ICC) | (psr & PSR_ICC);

    /* Prevent syscall restart.  */
    pt_regs_clear_syscall(regs);

    err |= __get_user(fpu_save, &sf->fpu_save);
    if (!err && fpu_save)
        err |= restore_fpu_state(regs, fpu_save);
    err |= __copy_from_user(&set, &sf->mask, sizeof(sigset_t));
    
    err |= __copy_from_user(&st, &sf->stack, sizeof(stack_t));
    
    if (err)
        goto segv;
        
    regs->pc = pc;
    regs->npc = npc;
    
    /* It is more difficult to avoid calling this function than to
     * call it and ignore errors.
     */
    old_fs = get_fs();
    set_fs(KERNEL_DS);
    do_sigaltstack((const stack_t __user *) &st, NULL, (unsigned long)sf);
    set_fs(old_fs);

    err |= __get_user(rwin_save, &sf->rwin_save);
    if (!err && rwin_save) {
        if (restore_rwin_state(rwin_save))
            goto segv;
    }

    set_current_blocked(&set);
    return;
segv:
    force_sig(SIGSEGV, current);
}

/* Checks if the fp is valid */
static inline int invalid_frame_pointer(void __user *fp, int fplen)
{
    if ((((unsigned long) fp) & 7) || !__access_ok((unsigned long)fp, fplen))
        return 1;

    return 0;
}

static inline void __user *get_sigframe(struct sigaction *sa, struct pt_regs *regs, unsigned long framesize)
{
    unsigned long sp = regs->u_regs[UREG_FP];

    /*
     * 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 (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize)))
        return (void __user *) -1L;

    /* This is the X/Open sanctioned signal stack switching.  */
    if (sa->sa_flags & SA_ONSTACK) {
        if (sas_ss_flags(sp) == 0)
            sp = current->sas_ss_sp + current->sas_ss_size;
    }

    sp -= framesize;

    /* Always align the stack frame.  This handles two cases.  First,
     * sigaltstack need not be mindful of platform specific stack
     * alignment.  Second, if we took this signal because the stack
     * is not aligned properly, we'd like to take the signal cleanly
     * and report that.
     */
    sp &= ~15UL;

    return (void __user *) sp;
}

static int setup_frame(struct k_sigaction *ka, struct pt_regs *regs,
               int signo, sigset_t *oldset)
{
    struct signal_frame __user *sf;
    int sigframe_size, err, wsaved;
    void __user *tail;

    /* 1. Make sure everything is clean */
    synchronize_user_stack();

    wsaved = current_thread_info()->w_saved;

    sigframe_size = sizeof(*sf);
    if (used_math())
        sigframe_size += sizeof(__siginfo_fpu_t);
    if (wsaved)
        sigframe_size += sizeof(__siginfo_rwin_t);

    sf = (struct signal_frame __user *)
        get_sigframe(&ka->sa, regs, sigframe_size);

    if (invalid_frame_pointer(sf, sigframe_size))
        goto sigill_and_return;

    tail = sf + 1;

    /* 2. Save the current process state */
    err = __copy_to_user(&sf->info.si_regs, regs, sizeof(struct pt_regs));
    
    err |= __put_user(0, &sf->extra_size);

    if (used_math()) {
        __siginfo_fpu_t __user *fp = tail;
        tail += sizeof(*fp);
        err |= save_fpu_state(regs, fp);
        err |= __put_user(fp, &sf->fpu_save);
    } else {
        err |= __put_user(0, &sf->fpu_save);
    }
    if (wsaved) {
        __siginfo_rwin_t __user *rwp = tail;
        tail += sizeof(*rwp);
        err |= save_rwin_state(wsaved, rwp);
        err |= __put_user(rwp, &sf->rwin_save);
    } else {
        err |= __put_user(0, &sf->rwin_save);
    }

    err |= __put_user(oldset->sig[0], &sf->info.si_mask);
    err |= __copy_to_user(sf->extramask, &oldset->sig[1],
                  (_NSIG_WORDS - 1) * sizeof(unsigned int));
    if (!wsaved) {
        err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
                      sizeof(struct reg_window32));
    } else {
        struct reg_window32 *rp;

        rp = &current_thread_info()->reg_window[wsaved - 1];
        err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
    }
    if (err)
        goto sigsegv;
    
    /* 3. signal handler back-trampoline and parameters */
    regs->u_regs[UREG_FP] = (unsigned long) sf;
    regs->u_regs[UREG_I0] = signo;
    regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
    regs->u_regs[UREG_I2] = (unsigned long) &sf->info;

    /* 4. signal handler */
    regs->pc = (unsigned long) ka->sa.sa_handler;
    regs->npc = (regs->pc + 4);

    /* 5. return to kernel instructions */
    if (ka->ka_restorer)
        regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
    else {
        regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

        /* mov __NR_sigreturn, %g1 */
        err |= __put_user(0x821020d8, &sf->insns[0]);

        /* t 0x10 */
        err |= __put_user(0x91d02010, &sf->insns[1]);
        if (err)
            goto sigsegv;

        /* Flush instruction space. */
        flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
    }
    return 0;

sigill_and_return:
    do_exit(SIGILL);
    return -EINVAL;

sigsegv:
    force_sigsegv(signo, current);
    return -EFAULT;
}

static int setup_rt_frame(struct k_sigaction *ka, struct pt_regs *regs,
              int signo, sigset_t *oldset, siginfo_t *info)
{
    struct rt_signal_frame __user *sf;
    int sigframe_size, wsaved;
    void __user *tail;
    unsigned int psr;
    int err;

    synchronize_user_stack();
    wsaved = current_thread_info()->w_saved;
    sigframe_size = sizeof(*sf);
    if (used_math())
        sigframe_size += sizeof(__siginfo_fpu_t);
    if (wsaved)
        sigframe_size += sizeof(__siginfo_rwin_t);
    sf = (struct rt_signal_frame __user *)
        get_sigframe(&ka->sa, regs, sigframe_size);
    if (invalid_frame_pointer(sf, sigframe_size))
        goto sigill;

    tail = sf + 1;
    err  = __put_user(regs->pc, &sf->regs.pc);
    err |= __put_user(regs->npc, &sf->regs.npc);
    err |= __put_user(regs->y, &sf->regs.y);
    psr = regs->psr;
    if (used_math())
        psr |= PSR_EF;
    err |= __put_user(psr, &sf->regs.psr);
    err |= __copy_to_user(&sf->regs.u_regs, regs->u_regs, sizeof(regs->u_regs));
    err |= __put_user(0, &sf->extra_size);

    if (psr & PSR_EF) {
        __siginfo_fpu_t *fp = tail;
        tail += sizeof(*fp);
        err |= save_fpu_state(regs, fp);
        err |= __put_user(fp, &sf->fpu_save);
    } else {
        err |= __put_user(0, &sf->fpu_save);
    }
    if (wsaved) {
        __siginfo_rwin_t *rwp = tail;
        tail += sizeof(*rwp);
        err |= save_rwin_state(wsaved, rwp);
        err |= __put_user(rwp, &sf->rwin_save);
    } else {
        err |= __put_user(0, &sf->rwin_save);
    }
    err |= __copy_to_user(&sf->mask, &oldset->sig[0], sizeof(sigset_t));
    
    /* Setup sigaltstack */
    err |= __put_user(current->sas_ss_sp, &sf->stack.ss_sp);
    err |= __put_user(sas_ss_flags(regs->u_regs[UREG_FP]), &sf->stack.ss_flags);
    err |= __put_user(current->sas_ss_size, &sf->stack.ss_size);
    
    if (!wsaved) {
        err |= __copy_to_user(sf, (char *) regs->u_regs[UREG_FP],
                      sizeof(struct reg_window32));
    } else {
        struct reg_window32 *rp;

        rp = &current_thread_info()->reg_window[wsaved - 1];
        err |= __copy_to_user(sf, rp, sizeof(struct reg_window32));
    }

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

    if (err)
        goto sigsegv;

    regs->u_regs[UREG_FP] = (unsigned long) sf;
    regs->u_regs[UREG_I0] = signo;
    regs->u_regs[UREG_I1] = (unsigned long) &sf->info;
    regs->u_regs[UREG_I2] = (unsigned long) &sf->regs;

    regs->pc = (unsigned long) ka->sa.sa_handler;
    regs->npc = (regs->pc + 4);

    if (ka->ka_restorer)
        regs->u_regs[UREG_I7] = (unsigned long)ka->ka_restorer;
    else {
        regs->u_regs[UREG_I7] = (unsigned long)(&(sf->insns[0]) - 2);

        /* mov __NR_sigreturn, %g1 */
        err |= __put_user(0x821020d8, &sf->insns[0]);

        /* t 0x10 */
        err |= __put_user(0x91d02010, &sf->insns[1]);
        if (err)
            goto sigsegv;

        /* Flush instruction space. */
        flush_sig_insns(current->mm, (unsigned long) &(sf->insns[0]));
    }
    return 0;

sigill:
    do_exit(SIGILL);
    return -EINVAL;

sigsegv:
    force_sigsegv(signo, current);
    return -EFAULT;
}

static inline void
handle_signal(unsigned long signr, struct k_sigaction *ka,
          siginfo_t *info, struct pt_regs *regs)
{
    sigset_t *oldset = sigmask_to_save();
    int err;

    if (ka->sa.sa_flags & SA_SIGINFO)
        err = setup_rt_frame(ka, regs, signr, oldset, info);
    else
        err = setup_frame(ka, regs, signr, oldset);

    if (err)
        return;

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

static inline void syscall_restart(unsigned long orig_i0, struct pt_regs *regs,
                   struct sigaction *sa)
{
    switch(regs->u_regs[UREG_I0]) {
    case ERESTART_RESTARTBLOCK:
    case ERESTARTNOHAND:
    no_system_call_restart:
        regs->u_regs[UREG_I0] = EINTR;
        regs->psr |= PSR_C;
        break;
    case ERESTARTSYS:
        if (!(sa->sa_flags & SA_RESTART))
            goto no_system_call_restart;
        /* fallthrough */
    case ERESTARTNOINTR:
        regs->u_regs[UREG_I0] = orig_i0;
        regs->pc -= 4;
        regs->npc -= 4;
    }
}

/* 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, unsigned long orig_i0)
{
    struct k_sigaction ka;
    int restart_syscall;
    siginfo_t info;
    int signr;

    /* It's a lot of work and synchronization to add a new ptrace
     * register for GDB to save and restore in order to get
     * orig_i0 correct for syscall restarts when debugging.
     *
     * Although it should be the case that most of the global
     * registers are volatile across a system call, glibc already
     * depends upon that fact that we preserve them.  So we can't
     * just use any global register to save away the orig_i0 value.
     *
     * In particular %g2, %g3, %g4, and %g5 are all assumed to be
     * preserved across a system call trap by various pieces of
     * code in glibc.
     *
     * %g7 is used as the "thread register".   %g6 is not used in
     * any fixed manner.  %g6 is used as a scratch register and
     * a compiler temporary, but it's value is never used across
     * a system call.  Therefore %g6 is usable for orig_i0 storage.
     */
    if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C))
        regs->u_regs[UREG_G6] = orig_i0;

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

    /* If the debugger messes with the program counter, it clears
     * the software "in syscall" bit, directing us to not perform
     * a syscall restart.
     */
    restart_syscall = 0;
    if (pt_regs_is_syscall(regs) && (regs->psr & PSR_C)) {
        restart_syscall = 1;
        orig_i0 = regs->u_regs[UREG_G6];
    }


    if (signr > 0) {
        if (restart_syscall)
            syscall_restart(orig_i0, regs, &ka.sa);
        handle_signal(signr, &ka, &info, regs);
        return;
    }
    if (restart_syscall &&
        (regs->u_regs[UREG_I0] == ERESTARTNOHAND ||
         regs->u_regs[UREG_I0] == ERESTARTSYS ||
         regs->u_regs[UREG_I0] == ERESTARTNOINTR)) {
        /* replay the system call when we are done */
        regs->u_regs[UREG_I0] = orig_i0;
        regs->pc -= 4;
        regs->npc -= 4;
        pt_regs_clear_syscall(regs);
    }
    if (restart_syscall &&
        regs->u_regs[UREG_I0] == ERESTART_RESTARTBLOCK) {
        regs->u_regs[UREG_G1] = __NR_restart_syscall;
        regs->pc -= 4;
        regs->npc -= 4;
        pt_regs_clear_syscall(regs);
    }

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

void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0,
              unsigned long thread_info_flags)
{
    if (thread_info_flags & _TIF_SIGPENDING)
        do_signal(regs, orig_i0);
    if (thread_info_flags & _TIF_NOTIFY_RESUME) {
        clear_thread_flag(TIF_NOTIFY_RESUME);
        tracehook_notify_resume(regs);
    }
}

asmlinkage int
do_sys_sigstack(struct sigstack __user *ssptr, struct sigstack __user *ossptr,
        unsigned long sp)
{
    int ret = -EFAULT;

    /* First see if old state is wanted. */
    if (ossptr) {
        if (put_user(current->sas_ss_sp + current->sas_ss_size,
                 &ossptr->the_stack) ||
            __put_user(on_sig_stack(sp), &ossptr->cur_status))
            goto out;
    }

    /* Now see if we want to update the new state. */
    if (ssptr) {
        char *ss_sp;

        if (get_user(ss_sp, &ssptr->the_stack))
            goto out;
        /* If the current stack was set with sigaltstack, don't
           swap stacks while we are on it.  */
        ret = -EPERM;
        if (current->sas_ss_sp && on_sig_stack(sp))
            goto out;

        /* Since we don't know the extent of the stack, and we don't
           track onstack-ness, but rather calculate it, we must
           presume a size.  Ho hum this interface is lossy.  */
        current->sas_ss_sp = (unsigned long)ss_sp - SIGSTKSZ;
        current->sas_ss_size = SIGSTKSZ;
    }
    ret = 0;
out:
    return ret;
}