signal.c
上传用户:lgb322
上传日期:2013-02-24
资源大小:30529k
文件大小:18k
- /*
- * linux/arch/i386/kernel/signal.c
- *
- * 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/smp_lock.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/personality.h>
- #include <asm/ucontext.h>
- #include <asm/uaccess.h>
- #include <asm/i387.h>
- #define DEBUG_SIG 0
- #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
- int FASTCALL(do_signal(struct pt_regs *regs, sigset_t *oldset));
- int copy_siginfo_to_user(siginfo_t *to, siginfo_t *from)
- {
- if (!access_ok (VERIFY_WRITE, to, sizeof(siginfo_t)))
- return -EFAULT;
- if (from->si_code < 0)
- return __copy_to_user(to, from, sizeof(siginfo_t));
- else {
- int err;
- /* If you change siginfo_t structure, please be sure
- this code is fixed accordingly.
- It should never copy any pad contained in the structure
- to avoid security leaks, but must copy the generic
- 3 ints plus the relevant union member. */
- err = __put_user(from->si_signo, &to->si_signo);
- err |= __put_user(from->si_errno, &to->si_errno);
- err |= __put_user((short)from->si_code, &to->si_code);
- /* First 32bits of unions are always present. */
- err |= __put_user(from->si_pid, &to->si_pid);
- switch (from->si_code >> 16) {
- case __SI_FAULT >> 16:
- break;
- case __SI_CHLD >> 16:
- err |= __put_user(from->si_utime, &to->si_utime);
- err |= __put_user(from->si_stime, &to->si_stime);
- err |= __put_user(from->si_status, &to->si_status);
- default:
- err |= __put_user(from->si_uid, &to->si_uid);
- break;
- /* case __SI_RT: This is not generated by the kernel as of now. */
- }
- return err;
- }
- }
- /*
- * Atomically swap in the new signal mask, and wait for a signal.
- */
- asmlinkage int
- sys_sigsuspend(int history0, int history1, old_sigset_t mask)
- {
- struct pt_regs * regs = (struct pt_regs *) &history0;
- sigset_t saveset;
- mask &= _BLOCKABLE;
- spin_lock_irq(¤t->sigmask_lock);
- saveset = current->blocked;
- siginitset(¤t->blocked, mask);
- recalc_sigpending(current);
- spin_unlock_irq(¤t->sigmask_lock);
- regs->eax = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(regs, &saveset))
- return -EINTR;
- }
- }
- asmlinkage int
- sys_rt_sigsuspend(sigset_t *unewset, size_t sigsetsize)
- {
- struct pt_regs * regs = (struct pt_regs *) &unewset;
- sigset_t saveset, newset;
- /* XXX: Don't preclude handling different sized sigset_t's. */
- if (sigsetsize != sizeof(sigset_t))
- return -EINVAL;
- if (copy_from_user(&newset, unewset, sizeof(newset)))
- return -EFAULT;
- sigdelsetmask(&newset, ~_BLOCKABLE);
- spin_lock_irq(¤t->sigmask_lock);
- saveset = current->blocked;
- current->blocked = newset;
- recalc_sigpending(current);
- spin_unlock_irq(¤t->sigmask_lock);
- regs->eax = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (do_signal(regs, &saveset))
- return -EINTR;
- }
- }
- asmlinkage int
- sys_sigaction(int sig, const struct old_sigaction *act,
- struct old_sigaction *oact)
- {
- struct k_sigaction new_ka, old_ka;
- int ret;
- if (act) {
- old_sigset_t mask;
- if (verify_area(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 (verify_area(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 *uss, stack_t *uoss)
- {
- struct pt_regs *regs = (struct pt_regs *) &uss;
- return do_sigaltstack(uss, uoss, regs->esp);
- }
- /*
- * Do a signal return; undo the signal stack.
- */
- struct sigframe
- {
- char *pretcode;
- int sig;
- struct sigcontext sc;
- struct _fpstate fpstate;
- unsigned long extramask[_NSIG_WORDS-1];
- char retcode[8];
- };
- struct rt_sigframe
- {
- char *pretcode;
- int sig;
- struct siginfo *pinfo;
- void *puc;
- struct siginfo info;
- struct ucontext uc;
- struct _fpstate fpstate;
- char retcode[8];
- };
- static int
- restore_sigcontext(struct pt_regs *regs, struct sigcontext *sc, int *peax)
- {
- unsigned int err = 0;
- #define COPY(x) err |= __get_user(regs->x, &sc->x)
- #define COPY_SEG(seg)
- { unsigned short tmp;
- err |= __get_user(tmp, &sc->seg);
- regs->x##seg = tmp; }
- #define COPY_SEG_STRICT(seg)
- { unsigned short tmp;
- err |= __get_user(tmp, &sc->seg);
- regs->x##seg = tmp|3; }
- #define GET_SEG(seg)
- { unsigned short tmp;
- err |= __get_user(tmp, &sc->seg);
- loadsegment(seg,tmp); }
- GET_SEG(gs);
- GET_SEG(fs);
- COPY_SEG(es);
- COPY_SEG(ds);
- COPY(edi);
- COPY(esi);
- COPY(ebp);
- COPY(esp);
- COPY(ebx);
- COPY(edx);
- COPY(ecx);
- COPY(eip);
- COPY_SEG_STRICT(cs);
- COPY_SEG_STRICT(ss);
-
- {
- unsigned int tmpflags;
- err |= __get_user(tmpflags, &sc->eflags);
- regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
- regs->orig_eax = -1; /* disable syscall checks */
- }
- {
- struct _fpstate * buf;
- err |= __get_user(buf, &sc->fpstate);
- if (buf) {
- if (verify_area(VERIFY_READ, buf, sizeof(*buf)))
- goto badframe;
- err |= restore_i387(buf);
- }
- }
- err |= __get_user(*peax, &sc->eax);
- return err;
- badframe:
- return 1;
- }
- asmlinkage int sys_sigreturn(unsigned long __unused)
- {
- struct pt_regs *regs = (struct pt_regs *) &__unused;
- struct sigframe *frame = (struct sigframe *)(regs->esp - 8);
- sigset_t set;
- int eax;
- if (verify_area(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(¤t->sigmask_lock);
- current->blocked = set;
- recalc_sigpending(current);
- spin_unlock_irq(¤t->sigmask_lock);
-
- if (restore_sigcontext(regs, &frame->sc, &eax))
- goto badframe;
- return eax;
- badframe:
- force_sig(SIGSEGV, current);
- return 0;
- }
- asmlinkage int sys_rt_sigreturn(unsigned long __unused)
- {
- struct pt_regs *regs = (struct pt_regs *) &__unused;
- struct rt_sigframe *frame = (struct rt_sigframe *)(regs->esp - 4);
- sigset_t set;
- stack_t st;
- int eax;
- if (verify_area(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(¤t->sigmask_lock);
- current->blocked = set;
- recalc_sigpending(current);
- spin_unlock_irq(¤t->sigmask_lock);
-
- if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
- goto badframe;
- if (__copy_from_user(&st, &frame->uc.uc_stack, sizeof(st)))
- goto badframe;
- /* It is more difficult to avoid calling this function than to
- call it and ignore errors. */
- do_sigaltstack(&st, NULL, regs->esp);
- return eax;
- badframe:
- force_sig(SIGSEGV, current);
- return 0;
- }
- /*
- * Set up a signal frame.
- */
- static int
- setup_sigcontext(struct sigcontext *sc, struct _fpstate *fpstate,
- struct pt_regs *regs, unsigned long mask)
- {
- int tmp, err = 0;
- tmp = 0;
- __asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
- err |= __put_user(tmp, (unsigned int *)&sc->gs);
- __asm__("movl %%fs,%0" : "=r"(tmp): "0"(tmp));
- err |= __put_user(tmp, (unsigned int *)&sc->fs);
- err |= __put_user(regs->xes, (unsigned int *)&sc->es);
- err |= __put_user(regs->xds, (unsigned int *)&sc->ds);
- err |= __put_user(regs->edi, &sc->edi);
- err |= __put_user(regs->esi, &sc->esi);
- err |= __put_user(regs->ebp, &sc->ebp);
- err |= __put_user(regs->esp, &sc->esp);
- err |= __put_user(regs->ebx, &sc->ebx);
- err |= __put_user(regs->edx, &sc->edx);
- err |= __put_user(regs->ecx, &sc->ecx);
- err |= __put_user(regs->eax, &sc->eax);
- err |= __put_user(current->thread.trap_no, &sc->trapno);
- err |= __put_user(current->thread.error_code, &sc->err);
- err |= __put_user(regs->eip, &sc->eip);
- err |= __put_user(regs->xcs, (unsigned int *)&sc->cs);
- err |= __put_user(regs->eflags, &sc->eflags);
- err |= __put_user(regs->esp, &sc->esp_at_signal);
- err |= __put_user(regs->xss, (unsigned int *)&sc->ss);
- tmp = save_i387(fpstate);
- if (tmp < 0)
- err = 1;
- else
- err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
- /* non-iBCS2 extensions.. */
- err |= __put_user(mask, &sc->oldmask);
- err |= __put_user(current->thread.cr2, &sc->cr2);
- return err;
- }
- /*
- * Determine which stack to use..
- */
- static inline void *
- get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
- {
- unsigned long esp;
- /* Default to using normal stack */
- esp = regs->esp;
- /* This is the X/Open sanctioned signal stack switching. */
- if (ka->sa.sa_flags & SA_ONSTACK) {
- if (sas_ss_flags(esp) == 0)
- esp = current->sas_ss_sp + current->sas_ss_size;
- }
- /* This is the legacy signal stack switching. */
- else if ((regs->xss & 0xffff) != __USER_DS &&
- !(ka->sa.sa_flags & SA_RESTORER) &&
- ka->sa.sa_restorer) {
- esp = (unsigned long) ka->sa.sa_restorer;
- }
- return (void *)((esp - frame_size) & -8ul);
- }
- static void setup_frame(int sig, struct k_sigaction *ka,
- sigset_t *set, struct pt_regs * regs)
- {
- struct sigframe *frame;
- int err = 0;
- frame = get_sigframe(ka, regs, sizeof(*frame));
- if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
- goto give_sigsegv;
- err |= __put_user((current->exec_domain
- && current->exec_domain->signal_invmap
- && sig < 32
- ? current->exec_domain->signal_invmap[sig]
- : sig),
- &frame->sig);
- if (err)
- goto give_sigsegv;
- err |= setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
- if (err)
- goto give_sigsegv;
- if (_NSIG_WORDS > 1) {
- err |= __copy_to_user(frame->extramask, &set->sig[1],
- sizeof(frame->extramask));
- }
- if (err)
- goto give_sigsegv;
- /* Set up to return from userspace. If provided, use a stub
- already in userspace. */
- if (ka->sa.sa_flags & SA_RESTORER) {
- err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
- } else {
- err |= __put_user(frame->retcode, &frame->pretcode);
- /* This is popl %eax ; movl $,%eax ; int $0x80 */
- err |= __put_user(0xb858, (short *)(frame->retcode+0));
- err |= __put_user(__NR_sigreturn, (int *)(frame->retcode+2));
- err |= __put_user(0x80cd, (short *)(frame->retcode+6));
- }
- if (err)
- goto give_sigsegv;
- /* Set up registers for signal handler */
- regs->esp = (unsigned long) frame;
- regs->eip = (unsigned long) ka->sa.sa_handler;
- set_fs(USER_DS);
- regs->xds = __USER_DS;
- regs->xes = __USER_DS;
- regs->xss = __USER_DS;
- regs->xcs = __USER_CS;
- regs->eflags &= ~TF_MASK;
- #if DEBUG_SIG
- printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%pn",
- current->comm, current->pid, frame, regs->eip, frame->pretcode);
- #endif
- return;
- give_sigsegv:
- if (sig == SIGSEGV)
- ka->sa.sa_handler = SIG_DFL;
- force_sig(SIGSEGV, current);
- }
- static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
- sigset_t *set, struct pt_regs * regs)
- {
- struct rt_sigframe *frame;
- int err = 0;
- frame = get_sigframe(ka, regs, sizeof(*frame));
- if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
- goto give_sigsegv;
- err |= __put_user((current->exec_domain
- && current->exec_domain->signal_invmap
- && sig < 32
- ? current->exec_domain->signal_invmap[sig]
- : 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);
- 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->esp),
- &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, &frame->fpstate,
- 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. If provided, use a stub
- already in userspace. */
- if (ka->sa.sa_flags & SA_RESTORER) {
- err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
- } else {
- err |= __put_user(frame->retcode, &frame->pretcode);
- /* This is movl $,%eax ; int $0x80 */
- err |= __put_user(0xb8, (char *)(frame->retcode+0));
- err |= __put_user(__NR_rt_sigreturn, (int *)(frame->retcode+1));
- err |= __put_user(0x80cd, (short *)(frame->retcode+5));
- }
- if (err)
- goto give_sigsegv;
- /* Set up registers for signal handler */
- regs->esp = (unsigned long) frame;
- regs->eip = (unsigned long) ka->sa.sa_handler;
- set_fs(USER_DS);
- regs->xds = __USER_DS;
- regs->xes = __USER_DS;
- regs->xss = __USER_DS;
- regs->xcs = __USER_CS;
- regs->eflags &= ~TF_MASK;
- #if DEBUG_SIG
- printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%pn",
- current->comm, current->pid, frame, regs->eip, frame->pretcode);
- #endif
- return;
- give_sigsegv:
- if (sig == SIGSEGV)
- ka->sa.sa_handler = SIG_DFL;
- force_sig(SIGSEGV, current);
- }
- /*
- * OK, we're invoking a handler
- */
- static void
- handle_signal(unsigned long sig, struct k_sigaction *ka,
- siginfo_t *info, sigset_t *oldset, struct pt_regs * regs)
- {
- /* Are we from a system call? */
- if (regs->orig_eax >= 0) {
- /* If so, check system call restarting.. */
- switch (regs->eax) {
- case -ERESTARTNOHAND:
- regs->eax = -EINTR;
- break;
- case -ERESTARTSYS:
- if (!(ka->sa.sa_flags & SA_RESTART)) {
- regs->eax = -EINTR;
- break;
- }
- /* fallthrough */
- case -ERESTARTNOINTR:
- regs->eax = regs->orig_eax;
- regs->eip -= 2;
- }
- }
- /* Set up the stack frame */
- if (ka->sa.sa_flags & SA_SIGINFO)
- setup_rt_frame(sig, ka, info, oldset, regs);
- else
- setup_frame(sig, ka, oldset, regs);
- if (ka->sa.sa_flags & SA_ONESHOT)
- ka->sa.sa_handler = SIG_DFL;
- if (!(ka->sa.sa_flags & SA_NODEFER)) {
- spin_lock_irq(¤t->sigmask_lock);
- sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask);
- sigaddset(¤t->blocked,sig);
- recalc_sigpending(current);
- spin_unlock_irq(¤t->sigmask_lock);
- }
- }
- /*
- * 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.
- */
- int do_signal(struct pt_regs *regs, sigset_t *oldset)
- {
- siginfo_t info;
- 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 ((regs->xcs & 3) != 3)
- return 1;
- if (!oldset)
- oldset = ¤t->blocked;
- for (;;) {
- unsigned long signr;
- spin_lock_irq(¤t->sigmask_lock);
- signr = dequeue_signal(¤t->blocked, &info);
- spin_unlock_irq(¤t->sigmask_lock);
- if (!signr)
- break;
- if ((current->ptrace & PT_PTRACED) && signr != SIGKILL) {
- /* Let the debugger run. */
- current->exit_code = signr;
- current->state = TASK_STOPPED;
- notify_parent(current, SIGCHLD);
- schedule();
- /* We're back. Did the debugger cancel the sig? */
- if (!(signr = current->exit_code))
- continue;
- current->exit_code = 0;
- /* The debugger continued. Ignore SIGSTOP. */
- if (signr == SIGSTOP)
- continue;
- /* Update the siginfo structure. Is this good? */
- if (signr != info.si_signo) {
- info.si_signo = signr;
- info.si_errno = 0;
- info.si_code = SI_USER;
- info.si_pid = current->p_pptr->pid;
- info.si_uid = current->p_pptr->uid;
- }
- /* If the (new) signal is now blocked, requeue it. */
- if (sigismember(¤t->blocked, signr)) {
- send_sig_info(signr, &info, current);
- continue;
- }
- }
- ka = ¤t->sig->action[signr-1];
- if (ka->sa.sa_handler == SIG_IGN) {
- if (signr != SIGCHLD)
- continue;
- /* Check for SIGCHLD: it's special. */
- while (sys_wait4(-1, NULL, WNOHANG, NULL) > 0)
- /* nothing */;
- continue;
- }
- if (ka->sa.sa_handler == SIG_DFL) {
- int exit_code = signr;
- /* Init gets no signals it doesn't want. */
- if (current->pid == 1)
- continue;
- switch (signr) {
- case SIGCONT: case SIGCHLD: case SIGWINCH:
- continue;
- case SIGTSTP: case SIGTTIN: case SIGTTOU:
- if (is_orphaned_pgrp(current->pgrp))
- continue;
- /* FALLTHRU */
- case SIGSTOP: {
- struct signal_struct *sig;
- current->state = TASK_STOPPED;
- current->exit_code = signr;
- sig = current->p_pptr->sig;
- if (sig && !(sig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDSTOP))
- notify_parent(current, SIGCHLD);
- schedule();
- continue;
- }
- case SIGQUIT: case SIGILL: case SIGTRAP:
- case SIGABRT: case SIGFPE: case SIGSEGV:
- case SIGBUS: case SIGSYS: case SIGXCPU: case SIGXFSZ:
- if (do_coredump(signr, regs))
- exit_code |= 0x80;
- /* FALLTHRU */
- default:
- sigaddset(¤t->pending.signal, signr);
- recalc_sigpending(current);
- current->flags |= PF_SIGNALED;
- do_exit(exit_code);
- /* NOTREACHED */
- }
- }
- /* Reenable any watchpoints before delivering the
- * signal to user space. The processor register will
- * have been cleared if the watchpoint triggered
- * inside the kernel.
- */
- __asm__("movl %0,%%db7" : : "r" (current->thread.debugreg[7]));
- /* Whee! Actually deliver the signal. */
- handle_signal(signr, ka, &info, oldset, regs);
- return 1;
- }
- /* Did we come from a system call? */
- if (regs->orig_eax >= 0) {
- /* Restart the system call - no handlers present */
- if (regs->eax == -ERESTARTNOHAND ||
- regs->eax == -ERESTARTSYS ||
- regs->eax == -ERESTARTNOINTR) {
- regs->eax = regs->orig_eax;
- regs->eip -= 2;
- }
- }
- return 0;
- }