signal.c

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/*
 * Copyright (C) 2003 PathScale, Inc.
 * Copyright (C) 2003 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */


#include <linux/personality.h>
#include <linux/ptrace.h>
#include <linux/kernel.h>
#include <asm/unistd.h>
#include <asm/uaccess.h>
#include <asm/ucontext.h>
#include <frame_kern.h>
#include <skas.h>

#ifdef CONFIG_X86_32

/*
 * FPU tag word conversions.
 */

static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
{
    unsigned int tmp; /* to avoid 16 bit prefixes in the code */

    /* Transform each pair of bits into 01 (valid) or 00 (empty) */
    tmp = ~twd;
    tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
    /* and move the valid bits to the lower byte. */
    tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
    tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
    tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
    return tmp;
}

static inline unsigned long twd_fxsr_to_i387(struct user_fxsr_struct *fxsave)
{
    struct _fpxreg *st = NULL;
    unsigned long twd = (unsigned long) fxsave->twd;
    unsigned long tag;
    unsigned long ret = 0xffff0000;
    int i;

#define FPREG_ADDR(f, n)    ((char *)&(f)->st_space + (n) * 16)

    for (i = 0; i < 8; i++) {
        if (twd & 0x1) {
            st = (struct _fpxreg *) FPREG_ADDR(fxsave, i);

            switch (st->exponent & 0x7fff) {
            case 0x7fff:
                tag = 2;        /* Special */
                break;
            case 0x0000:
                if ( !st->significand[0] &&
                     !st->significand[1] &&
                     !st->significand[2] &&
                     !st->significand[3] ) {
                    tag = 1;    /* Zero */
                } else {
                    tag = 2;    /* Special */
                }
                break;
            default:
                if (st->significand[3] & 0x8000) {
                    tag = 0;    /* Valid */
                } else {
                    tag = 2;    /* Special */
                }
                break;
            }
        } else {
            tag = 3;            /* Empty */
        }
        ret |= (tag << (2 * i));
        twd = twd >> 1;
    }
    return ret;
}

static int convert_fxsr_to_user(struct _fpstate __user *buf,
                struct user_fxsr_struct *fxsave)
{
    unsigned long env[7];
    struct _fpreg __user *to;
    struct _fpxreg *from;
    int i;

    env[0] = (unsigned long)fxsave->cwd | 0xffff0000ul;
    env[1] = (unsigned long)fxsave->swd | 0xffff0000ul;
    env[2] = twd_fxsr_to_i387(fxsave);
    env[3] = fxsave->fip;
    env[4] = fxsave->fcs | ((unsigned long)fxsave->fop << 16);
    env[5] = fxsave->foo;
    env[6] = fxsave->fos;

    if (__copy_to_user(buf, env, 7 * sizeof(unsigned long)))
        return 1;

    to = &buf->_st[0];
    from = (struct _fpxreg *) &fxsave->st_space[0];
    for (i = 0; i < 8; i++, to++, from++) {
        unsigned long __user *t = (unsigned long __user *)to;
        unsigned long *f = (unsigned long *)from;

        if (__put_user(*f, t) ||
                __put_user(*(f + 1), t + 1) ||
                __put_user(from->exponent, &to->exponent))
            return 1;
    }
    return 0;
}

static int convert_fxsr_from_user(struct user_fxsr_struct *fxsave,
                  struct _fpstate __user *buf)
{
    unsigned long env[7];
    struct _fpxreg *to;
    struct _fpreg __user *from;
    int i;

    if (copy_from_user( env, buf, 7 * sizeof(long)))
        return 1;

    fxsave->cwd = (unsigned short)(env[0] & 0xffff);
    fxsave->swd = (unsigned short)(env[1] & 0xffff);
    fxsave->twd = twd_i387_to_fxsr((unsigned short)(env[2] & 0xffff));
    fxsave->fip = env[3];
    fxsave->fop = (unsigned short)((env[4] & 0xffff0000ul) >> 16);
    fxsave->fcs = (env[4] & 0xffff);
    fxsave->foo = env[5];
    fxsave->fos = env[6];

    to = (struct _fpxreg *) &fxsave->st_space[0];
    from = &buf->_st[0];
    for (i = 0; i < 8; i++, to++, from++) {
        unsigned long *t = (unsigned long *)to;
        unsigned long __user *f = (unsigned long __user *)from;

        if (__get_user(*t, f) ||
            __get_user(*(t + 1), f + 1) ||
            __get_user(to->exponent, &from->exponent))
            return 1;
    }
    return 0;
}

extern int have_fpx_regs;

#endif

static int copy_sc_from_user(struct pt_regs *regs,
                 struct sigcontext __user *from)
{
    struct sigcontext sc;
    int err, pid;

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

    err = copy_from_user(&sc, from, sizeof(sc));
    if (err)
        return err;

#define GETREG(regno, regname) regs->regs.gp[HOST_##regno] = sc.regname

#ifdef CONFIG_X86_32
    GETREG(GS, gs);
    GETREG(FS, fs);
    GETREG(ES, es);
    GETREG(DS, ds);
#endif
    GETREG(DI, di);
    GETREG(SI, si);
    GETREG(BP, bp);
    GETREG(SP, sp);
    GETREG(BX, bx);
    GETREG(DX, dx);
    GETREG(CX, cx);
    GETREG(AX, ax);
    GETREG(IP, ip);

#ifdef CONFIG_X86_64
    GETREG(R8, r8);
    GETREG(R9, r9);
    GETREG(R10, r10);
    GETREG(R11, r11);
    GETREG(R12, r12);
    GETREG(R13, r13);
    GETREG(R14, r14);
    GETREG(R15, r15);
#endif

    GETREG(CS, cs);
    GETREG(EFLAGS, flags);
#ifdef CONFIG_X86_32
    GETREG(SS, ss);
#endif

#undef GETREG

    pid = userspace_pid[current_thread_info()->cpu];
#ifdef CONFIG_X86_32
    if (have_fpx_regs) {
        struct user_fxsr_struct fpx;

        err = copy_from_user(&fpx,
            &((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
                     sizeof(struct user_fxsr_struct));
        if (err)
            return 1;

        err = convert_fxsr_from_user(&fpx, sc.fpstate);
        if (err)
            return 1;

        err = restore_fpx_registers(pid, (unsigned long *) &fpx);
        if (err < 0) {
            printk(KERN_ERR "copy_sc_from_user - "
                   "restore_fpx_registers failed, errno = %d\n",
                   -err);
            return 1;
        }
    } else
#endif
    {
        struct user_i387_struct fp;

        err = copy_from_user(&fp, sc.fpstate,
                     sizeof(struct user_i387_struct));
        if (err)
            return 1;

        err = restore_fp_registers(pid, (unsigned long *) &fp);
        if (err < 0) {
            printk(KERN_ERR "copy_sc_from_user - "
                   "restore_fp_registers failed, errno = %d\n",
                   -err);
            return 1;
        }
    }
    return 0;
}

static int copy_sc_to_user(struct sigcontext __user *to,
               struct _fpstate __user *to_fp, struct pt_regs *regs,
               unsigned long mask)
{
    struct sigcontext sc;
    struct faultinfo * fi = &current->thread.arch.faultinfo;
    int err, pid;
    memset(&sc, 0, sizeof(struct sigcontext));

#define PUTREG(regno, regname) sc.regname = regs->regs.gp[HOST_##regno]

#ifdef CONFIG_X86_32
    PUTREG(GS, gs);
    PUTREG(FS, fs);
    PUTREG(ES, es);
    PUTREG(DS, ds);
#endif
    PUTREG(DI, di);
    PUTREG(SI, si);
    PUTREG(BP, bp);
    PUTREG(SP, sp);
    PUTREG(BX, bx);
    PUTREG(DX, dx);
    PUTREG(CX, cx);
    PUTREG(AX, ax);
#ifdef CONFIG_X86_64
    PUTREG(R8, r8);
    PUTREG(R9, r9);
    PUTREG(R10, r10);
    PUTREG(R11, r11);
    PUTREG(R12, r12);
    PUTREG(R13, r13);
    PUTREG(R14, r14);
    PUTREG(R15, r15);
#endif

    sc.cr2 = fi->cr2;
    sc.err = fi->error_code;
    sc.trapno = fi->trap_no;
    PUTREG(IP, ip);
    PUTREG(CS, cs);
    PUTREG(EFLAGS, flags);
#ifdef CONFIG_X86_32
    PUTREG(SP, sp_at_signal);
    PUTREG(SS, ss);
#endif
#undef PUTREG
    sc.oldmask = mask;
    sc.fpstate = to_fp;

    err = copy_to_user(to, &sc, sizeof(struct sigcontext));
    if (err)
        return 1;

    pid = userspace_pid[current_thread_info()->cpu];

#ifdef CONFIG_X86_32
    if (have_fpx_regs) {
        struct user_fxsr_struct fpx;

        err = save_fpx_registers(pid, (unsigned long *) &fpx);
        if (err < 0){
            printk(KERN_ERR "copy_sc_to_user - save_fpx_registers "
                   "failed, errno = %d\n", err);
            return 1;
        }

        err = convert_fxsr_to_user(to_fp, &fpx);
        if (err)
            return 1;

        err |= __put_user(fpx.swd, &to_fp->status);
        err |= __put_user(X86_FXSR_MAGIC, &to_fp->magic);
        if (err)
            return 1;

        if (copy_to_user(&to_fp->_fxsr_env[0], &fpx,
                 sizeof(struct user_fxsr_struct)))
            return 1;
    } else
#endif
    {
        struct user_i387_struct fp;

        err = save_fp_registers(pid, (unsigned long *) &fp);
        if (copy_to_user(to_fp, &fp, sizeof(struct user_i387_struct)))
            return 1;
    }

    return 0;
}

#ifdef CONFIG_X86_32
static int copy_ucontext_to_user(struct ucontext __user *uc,
                 struct _fpstate __user *fp, sigset_t *set,
                 unsigned long sp)
{
    int err = 0;

    err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
    err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
    err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
    err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, 0);
    err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
    return err;
}

struct sigframe
{
    char __user *pretcode;
    int sig;
    struct sigcontext sc;
    struct _fpstate fpstate;
    unsigned long extramask[_NSIG_WORDS-1];
    char retcode[8];
};

struct rt_sigframe
{
    char __user *pretcode;
    int sig;
    struct siginfo __user *pinfo;
    void __user *puc;
    struct siginfo info;
    struct ucontext uc;
    struct _fpstate fpstate;
    char retcode[8];
};

int setup_signal_stack_sc(unsigned long stack_top, int sig,
              struct k_sigaction *ka, struct pt_regs *regs,
              sigset_t *mask)
{
    struct sigframe __user *frame;
    void __user *restorer;
    int err = 0;

    /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
    stack_top = ((stack_top + 4) & -16UL) - 4;
    frame = (struct sigframe __user *) stack_top - 1;
    if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
        return 1;

    restorer = frame->retcode;
    if (ka->sa.sa_flags & SA_RESTORER)
        restorer = ka->sa.sa_restorer;

    err |= __put_user(restorer, &frame->pretcode);
    err |= __put_user(sig, &frame->sig);
    err |= copy_sc_to_user(&frame->sc, &frame->fpstate, regs, mask->sig[0]);
    if (_NSIG_WORDS > 1)
        err |= __copy_to_user(&frame->extramask, &mask->sig[1],
                      sizeof(frame->extramask));

    /*
     * This is popl %eax ; movl $,%eax ; int $0x80
     *
     * WE DO NOT USE IT ANY MORE! It's only left here for historical
     * reasons and because gdb uses it as a signature to notice
     * signal handler stack frames.
     */
    err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
    err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
    err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));

    if (err)
        return err;

    PT_REGS_SP(regs) = (unsigned long) frame;
    PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
    PT_REGS_AX(regs) = (unsigned long) sig;
    PT_REGS_DX(regs) = (unsigned long) 0;
    PT_REGS_CX(regs) = (unsigned long) 0;
    return 0;
}

int setup_signal_stack_si(unsigned long stack_top, int sig,
              struct k_sigaction *ka, struct pt_regs *regs,
              siginfo_t *info, sigset_t *mask)
{
    struct rt_sigframe __user *frame;
    void __user *restorer;
    int err = 0;

    stack_top &= -8UL;
    frame = (struct rt_sigframe __user *) stack_top - 1;
    if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
        return 1;

    restorer = frame->retcode;
    if (ka->sa.sa_flags & SA_RESTORER)
        restorer = ka->sa.sa_restorer;

    err |= __put_user(restorer, &frame->pretcode);
    err |= __put_user(sig, &frame->sig);
    err |= __put_user(&frame->info, &frame->pinfo);
    err |= __put_user(&frame->uc, &frame->puc);
    err |= copy_siginfo_to_user(&frame->info, info);
    err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
                    PT_REGS_SP(regs));

    /*
     * This is movl $,%eax ; int $0x80
     *
     * WE DO NOT USE IT ANY MORE! It's only left here for historical
     * reasons and because gdb uses it as a signature to notice
     * signal handler stack frames.
     */
    err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
    err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
    err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));

    if (err)
        return err;

    PT_REGS_SP(regs) = (unsigned long) frame;
    PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
    PT_REGS_AX(regs) = (unsigned long) sig;
    PT_REGS_DX(regs) = (unsigned long) &frame->info;
    PT_REGS_CX(regs) = (unsigned long) &frame->uc;
    return 0;
}

long sys_sigreturn(struct pt_regs *regs)
{
    unsigned long sp = PT_REGS_SP(&current->thread.regs);
    struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
    sigset_t set;
    struct sigcontext __user *sc = &frame->sc;
    unsigned long __user *oldmask = &sc->oldmask;
    unsigned long __user *extramask = frame->extramask;
    int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);

    if (copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
        copy_from_user(&set.sig[1], extramask, sig_size))
        goto segfault;

    set_current_blocked(&set);

    if (copy_sc_from_user(&current->thread.regs, sc))
        goto segfault;

    /* Avoid ERESTART handling */
    PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
    return PT_REGS_SYSCALL_RET(&current->thread.regs);

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

#else

struct rt_sigframe
{
    char __user *pretcode;
    struct ucontext uc;
    struct siginfo info;
    struct _fpstate fpstate;
};

int setup_signal_stack_si(unsigned long stack_top, int sig,
              struct k_sigaction *ka, struct pt_regs * regs,
              siginfo_t *info, sigset_t *set)
{
    struct rt_sigframe __user *frame;
    int err = 0;
    struct task_struct *me = current;

    frame = (struct rt_sigframe __user *)
        round_down(stack_top - sizeof(struct rt_sigframe), 16);
    /* Subtract 128 for a red zone and 8 for proper alignment */
    frame = (struct rt_sigframe __user *) ((unsigned long) frame - 128 - 8);

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

    if (ka->sa.sa_flags & SA_SIGINFO) {
        err |= copy_siginfo_to_user(&frame->info, info);
        if (err)
            goto out;
    }

    /* Create the ucontext.  */
    err |= __put_user(0, &frame->uc.uc_flags);
    err |= __put_user(0, &frame->uc.uc_link);
    err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
    err |= __put_user(sas_ss_flags(PT_REGS_SP(regs)),
              &frame->uc.uc_stack.ss_flags);
    err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
    err |= copy_sc_to_user(&frame->uc.uc_mcontext, &frame->fpstate, regs,
                   set->sig[0]);
    err |= __put_user(&frame->fpstate, &frame->uc.uc_mcontext.fpstate);
    if (sizeof(*set) == 16) {
        err |= __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
        err |= __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
    }
    else
        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.
     */
    /* x86-64 should always use SA_RESTORER. */
    if (ka->sa.sa_flags & SA_RESTORER)
        err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
    else
        /* could use a vstub here */
        return err;

    if (err)
        return err;

    /* Set up registers for signal handler */
    {
        struct exec_domain *ed = current_thread_info()->exec_domain;
        if (unlikely(ed && ed->signal_invmap && sig < 32))
            sig = ed->signal_invmap[sig];
    }

    PT_REGS_SP(regs) = (unsigned long) frame;
    PT_REGS_DI(regs) = sig;
    /* In case the signal handler was declared without prototypes */
    PT_REGS_AX(regs) = 0;

    /*
     * This also works for non SA_SIGINFO handlers because they expect the
     * next argument after the signal number on the stack.
     */
    PT_REGS_SI(regs) = (unsigned long) &frame->info;
    PT_REGS_DX(regs) = (unsigned long) &frame->uc;
    PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 out:
    return err;
}
#endif

long sys_rt_sigreturn(struct pt_regs *regs)
{
    unsigned long sp = PT_REGS_SP(&current->thread.regs);
    struct rt_sigframe __user *frame =
        (struct rt_sigframe __user *)(sp - sizeof(long));
    struct ucontext __user *uc = &frame->uc;
    sigset_t set;

    if (copy_from_user(&set, &uc->uc_sigmask, sizeof(set)))
        goto segfault;

    set_current_blocked(&set);

    if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
        goto segfault;

    /* Avoid ERESTART handling */
    PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
    return PT_REGS_SYSCALL_RET(&current->thread.regs);

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

#ifdef CONFIG_X86_32
long ptregs_sigreturn(void)
{
    return sys_sigreturn(NULL);
}
long ptregs_rt_sigreturn(void)
{
    return sys_rt_sigreturn(NULL);
}
#endif