2005-04-17 06:20:36 +08:00
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/*
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* Copyright (C) 1991, 1992 Linus Torvalds
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*
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* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
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* 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
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*/
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#include <linux/sched.h>
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#include <linux/mm.h>
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#include <linux/smp.h>
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#include <linux/kernel.h>
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#include <linux/signal.h>
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#include <linux/errno.h>
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#include <linux/wait.h>
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#include <linux/unistd.h>
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#include <linux/stddef.h>
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#include <linux/personality.h>
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#include <linux/suspend.h>
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#include <linux/ptrace.h>
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#include <linux/elf.h>
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2007-02-13 20:26:26 +08:00
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#include <linux/binfmts.h>
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2005-04-17 06:20:36 +08:00
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#include <asm/processor.h>
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#include <asm/ucontext.h>
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#include <asm/uaccess.h>
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#include <asm/i387.h>
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2008-01-30 20:30:42 +08:00
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#include <asm/vdso.h>
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2007-10-11 17:12:46 +08:00
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#include "sigframe_32.h"
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2005-04-17 06:20:36 +08:00
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#define DEBUG_SIG 0
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#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
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/*
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* Atomically swap in the new signal mask, and wait for a signal.
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*/
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asmlinkage int
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sys_sigsuspend(int history0, int history1, old_sigset_t mask)
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{
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mask &= _BLOCKABLE;
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spin_lock_irq(¤t->sighand->siglock);
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2006-01-19 09:44:00 +08:00
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current->saved_sigmask = current->blocked;
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2005-04-17 06:20:36 +08:00
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siginitset(¤t->blocked, mask);
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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2006-01-19 09:44:00 +08:00
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current->state = TASK_INTERRUPTIBLE;
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schedule();
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set_thread_flag(TIF_RESTORE_SIGMASK);
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return -ERESTARTNOHAND;
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2005-04-17 06:20:36 +08:00
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}
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asmlinkage int
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sys_sigaction(int sig, const struct old_sigaction __user *act,
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struct old_sigaction __user *oact)
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{
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struct k_sigaction new_ka, old_ka;
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int ret;
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if (act) {
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old_sigset_t mask;
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if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
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__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
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__get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
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return -EFAULT;
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__get_user(new_ka.sa.sa_flags, &act->sa_flags);
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__get_user(mask, &act->sa_mask);
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siginitset(&new_ka.sa.sa_mask, mask);
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}
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ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
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if (!ret && oact) {
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if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
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__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
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__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
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return -EFAULT;
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__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
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__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
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}
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return ret;
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}
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asmlinkage int
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2008-01-30 20:30:56 +08:00
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sys_sigaltstack(unsigned long bx)
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2005-04-17 06:20:36 +08:00
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{
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/* This is needed to make gcc realize it doesn't own the "struct pt_regs" */
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2008-01-30 20:30:56 +08:00
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struct pt_regs *regs = (struct pt_regs *)&bx;
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const stack_t __user *uss = (const stack_t __user *)bx;
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stack_t __user *uoss = (stack_t __user *)regs->cx;
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2005-04-17 06:20:36 +08:00
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2008-01-30 20:30:56 +08:00
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return do_sigaltstack(uss, uoss, regs->sp);
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2005-04-17 06:20:36 +08:00
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}
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/*
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* Do a signal return; undo the signal stack.
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*/
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static int
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restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *peax)
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{
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unsigned int err = 0;
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/* Always make any pending restarted system calls return -EINTR */
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current_thread_info()->restart_block.fn = do_no_restart_syscall;
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2008-01-30 20:30:56 +08:00
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#define COPY(x) err |= __get_user(regs->x, &sc->x)
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2005-04-17 06:20:36 +08:00
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#define COPY_SEG(seg) \
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{ unsigned short tmp; \
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err |= __get_user(tmp, &sc->seg); \
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2008-01-30 20:30:56 +08:00
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regs->seg = tmp; }
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2005-04-17 06:20:36 +08:00
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#define COPY_SEG_STRICT(seg) \
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{ unsigned short tmp; \
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err |= __get_user(tmp, &sc->seg); \
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2008-01-30 20:30:56 +08:00
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regs->seg = tmp|3; }
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2005-04-17 06:20:36 +08:00
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#define GET_SEG(seg) \
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{ unsigned short tmp; \
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err |= __get_user(tmp, &sc->seg); \
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loadsegment(seg,tmp); }
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2006-03-23 18:59:40 +08:00
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#define FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_RF | \
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X86_EFLAGS_OF | X86_EFLAGS_DF | \
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2005-04-17 06:20:36 +08:00
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X86_EFLAGS_TF | X86_EFLAGS_SF | X86_EFLAGS_ZF | \
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X86_EFLAGS_AF | X86_EFLAGS_PF | X86_EFLAGS_CF)
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2007-02-13 20:26:20 +08:00
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GET_SEG(gs);
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COPY_SEG(fs);
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2005-04-17 06:20:36 +08:00
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COPY_SEG(es);
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COPY_SEG(ds);
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2008-01-30 20:30:56 +08:00
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COPY(di);
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COPY(si);
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COPY(bp);
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COPY(sp);
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COPY(bx);
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COPY(dx);
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COPY(cx);
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COPY(ip);
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2005-04-17 06:20:36 +08:00
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COPY_SEG_STRICT(cs);
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COPY_SEG_STRICT(ss);
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{
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unsigned int tmpflags;
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2008-01-30 20:30:56 +08:00
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err |= __get_user(tmpflags, &sc->flags);
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2008-01-30 20:30:56 +08:00
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regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
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regs->orig_ax = -1; /* disable syscall checks */
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2005-04-17 06:20:36 +08:00
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}
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{
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struct _fpstate __user * buf;
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err |= __get_user(buf, &sc->fpstate);
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if (buf) {
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if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
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goto badframe;
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err |= restore_i387(buf);
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} else {
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struct task_struct *me = current;
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if (used_math()) {
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clear_fpu(me);
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clear_used_math();
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}
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}
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}
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2008-01-30 20:30:56 +08:00
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err |= __get_user(*peax, &sc->ax);
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2005-04-17 06:20:36 +08:00
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return err;
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badframe:
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return 1;
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}
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asmlinkage int sys_sigreturn(unsigned long __unused)
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{
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struct pt_regs *regs = (struct pt_regs *) &__unused;
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2008-01-30 20:30:56 +08:00
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struct sigframe __user *frame = (struct sigframe __user *)(regs->sp - 8);
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2005-04-17 06:20:36 +08:00
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sigset_t set;
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2008-01-30 20:30:56 +08:00
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int ax;
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2005-04-17 06:20:36 +08:00
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if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
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goto badframe;
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if (__get_user(set.sig[0], &frame->sc.oldmask)
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|| (_NSIG_WORDS > 1
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&& __copy_from_user(&set.sig[1], &frame->extramask,
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sizeof(frame->extramask))))
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goto badframe;
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sigdelsetmask(&set, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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current->blocked = set;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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2008-01-30 20:30:56 +08:00
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if (restore_sigcontext(regs, &frame->sc, &ax))
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2005-04-17 06:20:36 +08:00
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goto badframe;
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2008-01-30 20:30:56 +08:00
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return ax;
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2005-04-17 06:20:36 +08:00
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badframe:
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2008-01-30 20:33:18 +08:00
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if (show_unhandled_signals && printk_ratelimit()) {
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2008-01-30 20:30:56 +08:00
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printk("%s%s[%d] bad frame in sigreturn frame:%p ip:%lx"
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2008-01-30 20:33:18 +08:00
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" sp:%lx oeax:%lx",
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2007-10-19 14:40:41 +08:00
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task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG,
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2008-01-30 20:30:56 +08:00
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current->comm, task_pid_nr(current), frame, regs->ip,
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regs->sp, regs->orig_ax);
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2008-01-30 20:33:18 +08:00
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print_vma_addr(" in ", regs->ip);
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printk("\n");
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}
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2007-07-22 17:12:28 +08:00
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2005-04-17 06:20:36 +08:00
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force_sig(SIGSEGV, current);
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return 0;
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}
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asmlinkage int sys_rt_sigreturn(unsigned long __unused)
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{
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struct pt_regs *regs = (struct pt_regs *) &__unused;
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2008-01-30 20:30:56 +08:00
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struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(regs->sp - 4);
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2005-04-17 06:20:36 +08:00
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sigset_t set;
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2008-01-30 20:30:56 +08:00
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int ax;
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2005-04-17 06:20:36 +08:00
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if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
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goto badframe;
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if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
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goto badframe;
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sigdelsetmask(&set, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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current->blocked = set;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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2008-01-30 20:30:56 +08:00
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if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax))
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2005-04-17 06:20:36 +08:00
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goto badframe;
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2008-01-30 20:30:56 +08:00
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if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT)
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2005-04-17 06:20:36 +08:00
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goto badframe;
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2008-01-30 20:30:56 +08:00
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return ax;
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2005-04-17 06:20:36 +08:00
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badframe:
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force_sig(SIGSEGV, current);
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return 0;
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}
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/*
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* Set up a signal frame.
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*/
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static int
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setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
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struct pt_regs *regs, unsigned long mask)
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{
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int tmp, err = 0;
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2008-01-30 20:30:56 +08:00
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err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs);
|
2007-02-13 20:26:20 +08:00
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savesegment(gs, tmp);
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err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
|
2005-04-17 06:20:36 +08:00
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2008-01-30 20:30:56 +08:00
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err |= __put_user(regs->es, (unsigned int __user *)&sc->es);
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err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds);
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2008-01-30 20:30:56 +08:00
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err |= __put_user(regs->di, &sc->di);
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err |= __put_user(regs->si, &sc->si);
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err |= __put_user(regs->bp, &sc->bp);
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err |= __put_user(regs->sp, &sc->sp);
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err |= __put_user(regs->bx, &sc->bx);
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err |= __put_user(regs->dx, &sc->dx);
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err |= __put_user(regs->cx, &sc->cx);
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err |= __put_user(regs->ax, &sc->ax);
|
2005-04-17 06:20:36 +08:00
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err |= __put_user(current->thread.trap_no, &sc->trapno);
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err |= __put_user(current->thread.error_code, &sc->err);
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2008-01-30 20:30:56 +08:00
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err |= __put_user(regs->ip, &sc->ip);
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2008-01-30 20:30:56 +08:00
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err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs);
|
2008-01-30 20:30:56 +08:00
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err |= __put_user(regs->flags, &sc->flags);
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err |= __put_user(regs->sp, &sc->sp_at_signal);
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2008-01-30 20:30:56 +08:00
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err |= __put_user(regs->ss, (unsigned int __user *)&sc->ss);
|
2005-04-17 06:20:36 +08:00
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tmp = save_i387(fpstate);
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if (tmp < 0)
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err = 1;
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else
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err |= __put_user(tmp ? fpstate : NULL, &sc->fpstate);
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|
|
|
/* 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 __user *
|
|
|
|
|
get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
|
|
|
|
|
{
|
2008-01-30 20:30:56 +08:00
|
|
|
unsigned long sp;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
/* Default to using normal stack */
|
2008-01-30 20:30:56 +08:00
|
|
|
sp = regs->sp;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
x86: protect against sigaltstack wraparound
cf http://lkml.org/lkml/2007/10/3/41
To summarize: on Linux, SA_ONSTACK decides whether you are already on the
signal stack based on the value of the SP at the time of a signal. If
you are not already inside the range, you are not "on the signal stack"
and so the new signal handler frame starts over at the base of the signal
stack.
sigaltstack (and sigstack before it) was invented in BSD. There, the
SA_ONSTACK behavior has always been different. It uses a kernel state
flag to decide, rather than the SP value. When you first take an
SA_ONSTACK signal and switch to the alternate signal stack, it sets the
SS_ONSTACK flag in the thread's sigaltstack state in the kernel.
Thereafter you are "on the signal stack" and don't switch SP before
pushing a handler frame no matter what the SP value is. Only when you
sigreturn from the original handler context do you clear the SS_ONSTACK
flag so that a new handler frame will start over at the base of the
alternate signal stack.
The undesireable effect of the Linux behavior is that an overflow of the
alternate signal stack can not only go undetected, but lead to a ring
buffer effect of clobbering the original handler frame at the base of the
signal stack for each successive signal that comes just after the
overflow. This is what Shi Weihua's test case demonstrates. Normally
this does not come up because of the signal mask, but the test case uses
SA_NODEFER for its SIGSEGV handler.
The other subtle part of the existing Linux semantics is that a simple
longjmp out of a signal handler serves to take you off the signal stack
in a safe and reliable fashion without having used sigreturn (nor having
just returned from the handler normally, which means the same). After
the longjmp (or even informal stack switching not via any proper libc or
kernel interface), the alternate signal stack stands ready to be used
again.
A paranoid program would allocate a PROT_NONE red zone around its
alternate signal stack. Then a small overflow would trigger a SIGSEGV in
handler setup, and be fatal (core dump) whether or not SIGSEGV is
blocked. As with thread stack red zones, that cannot catch all overflows
(or underflows). e.g., a local array as large as page size allocated in
a function called from a handler, but not actually touched before more
calls push more stack, could cause an overflow that silently pushes into
some unrelated allocated pages.
The BSD behavior does not do anything in particular about overflow. But
it does at least avoid the wraparound or "ring buffer effect", so you'll
just get a straightforward all-out overflow down your address space past
the low end of the alternate signal stack. I don't know what the BSD
behavior is for longjmp out of an SA_ONSTACK handler.
The POSIX wording relating to sigaltstack is pretty minimal. I don't
think it speaks to this issue one way or another. (The program that
overflows its stack is clearly in undefined behavior territory of one
sort or another anyhow.)
Given the longjmp issue and the potential for highly subtle complications
in existing programs relying on this in arcane ways deep in their code, I
am very dubious about changing the behavior to the BSD style persistent
flag. I think Shi Weihua's patches have a similar effect by tracking the
SP used in the last handler setup.
I think it would be sensible for the signal handler setup code to detect
when it would itself be causing a stack overflow. Maybe something like
the following patch (untested). This issue exists in the same way on all
machines, so ideally they would all do a similar check.
When it's the handler function itself or its callees that cause the
overflow, rather than the signal handler frame setup alone crossing the
boundary, this still won't help. But I don't see any way to distinguish
that from the valid longjmp case.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 20:30:06 +08:00
|
|
|
/*
|
|
|
|
|
* 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.
|
|
|
|
|
*/
|
2008-01-30 20:30:56 +08:00
|
|
|
if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
|
x86: protect against sigaltstack wraparound
cf http://lkml.org/lkml/2007/10/3/41
To summarize: on Linux, SA_ONSTACK decides whether you are already on the
signal stack based on the value of the SP at the time of a signal. If
you are not already inside the range, you are not "on the signal stack"
and so the new signal handler frame starts over at the base of the signal
stack.
sigaltstack (and sigstack before it) was invented in BSD. There, the
SA_ONSTACK behavior has always been different. It uses a kernel state
flag to decide, rather than the SP value. When you first take an
SA_ONSTACK signal and switch to the alternate signal stack, it sets the
SS_ONSTACK flag in the thread's sigaltstack state in the kernel.
Thereafter you are "on the signal stack" and don't switch SP before
pushing a handler frame no matter what the SP value is. Only when you
sigreturn from the original handler context do you clear the SS_ONSTACK
flag so that a new handler frame will start over at the base of the
alternate signal stack.
The undesireable effect of the Linux behavior is that an overflow of the
alternate signal stack can not only go undetected, but lead to a ring
buffer effect of clobbering the original handler frame at the base of the
signal stack for each successive signal that comes just after the
overflow. This is what Shi Weihua's test case demonstrates. Normally
this does not come up because of the signal mask, but the test case uses
SA_NODEFER for its SIGSEGV handler.
The other subtle part of the existing Linux semantics is that a simple
longjmp out of a signal handler serves to take you off the signal stack
in a safe and reliable fashion without having used sigreturn (nor having
just returned from the handler normally, which means the same). After
the longjmp (or even informal stack switching not via any proper libc or
kernel interface), the alternate signal stack stands ready to be used
again.
A paranoid program would allocate a PROT_NONE red zone around its
alternate signal stack. Then a small overflow would trigger a SIGSEGV in
handler setup, and be fatal (core dump) whether or not SIGSEGV is
blocked. As with thread stack red zones, that cannot catch all overflows
(or underflows). e.g., a local array as large as page size allocated in
a function called from a handler, but not actually touched before more
calls push more stack, could cause an overflow that silently pushes into
some unrelated allocated pages.
The BSD behavior does not do anything in particular about overflow. But
it does at least avoid the wraparound or "ring buffer effect", so you'll
just get a straightforward all-out overflow down your address space past
the low end of the alternate signal stack. I don't know what the BSD
behavior is for longjmp out of an SA_ONSTACK handler.
The POSIX wording relating to sigaltstack is pretty minimal. I don't
think it speaks to this issue one way or another. (The program that
overflows its stack is clearly in undefined behavior territory of one
sort or another anyhow.)
Given the longjmp issue and the potential for highly subtle complications
in existing programs relying on this in arcane ways deep in their code, I
am very dubious about changing the behavior to the BSD style persistent
flag. I think Shi Weihua's patches have a similar effect by tracking the
SP used in the last handler setup.
I think it would be sensible for the signal handler setup code to detect
when it would itself be causing a stack overflow. Maybe something like
the following patch (untested). This issue exists in the same way on all
machines, so ideally they would all do a similar check.
When it's the handler function itself or its callees that cause the
overflow, rather than the signal handler frame setup alone crossing the
boundary, this still won't help. But I don't see any way to distinguish
that from the valid longjmp case.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 20:30:06 +08:00
|
|
|
return (void __user *) -1L;
|
|
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
/* This is the X/Open sanctioned signal stack switching. */
|
|
|
|
|
if (ka->sa.sa_flags & SA_ONSTACK) {
|
2008-01-30 20:30:56 +08:00
|
|
|
if (sas_ss_flags(sp) == 0)
|
|
|
|
|
sp = current->sas_ss_sp + current->sas_ss_size;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* This is the legacy signal stack switching. */
|
2008-01-30 20:30:56 +08:00
|
|
|
else if ((regs->ss & 0xffff) != __USER_DS &&
|
2005-04-17 06:20:36 +08:00
|
|
|
!(ka->sa.sa_flags & SA_RESTORER) &&
|
|
|
|
|
ka->sa.sa_restorer) {
|
2008-01-30 20:30:56 +08:00
|
|
|
sp = (unsigned long) ka->sa.sa_restorer;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
2008-01-30 20:30:56 +08:00
|
|
|
sp -= frame_size;
|
2005-10-10 00:54:23 +08:00
|
|
|
/* Align the stack pointer according to the i386 ABI,
|
|
|
|
|
* i.e. so that on function entry ((sp + 4) & 15) == 0. */
|
2008-01-30 20:30:56 +08:00
|
|
|
sp = ((sp + 4) & -16ul) - 4;
|
|
|
|
|
return (void __user *) sp;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* These symbols are defined with the addresses in the vsyscall page.
|
|
|
|
|
See vsyscall-sigreturn.S. */
|
|
|
|
|
extern void __user __kernel_sigreturn;
|
|
|
|
|
extern void __user __kernel_rt_sigreturn;
|
|
|
|
|
|
2005-06-23 15:08:21 +08:00
|
|
|
static int setup_frame(int sig, struct k_sigaction *ka,
|
|
|
|
|
sigset_t *set, struct pt_regs * regs)
|
2005-04-17 06:20:36 +08:00
|
|
|
{
|
|
|
|
|
void __user *restorer;
|
|
|
|
|
struct sigframe __user *frame;
|
|
|
|
|
int err = 0;
|
|
|
|
|
int usig;
|
|
|
|
|
|
|
|
|
|
frame = get_sigframe(ka, regs, sizeof(*frame));
|
|
|
|
|
|
|
|
|
|
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
|
|
|
|
|
goto give_sigsegv;
|
|
|
|
|
|
|
|
|
|
usig = 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(usig, &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;
|
|
|
|
|
}
|
|
|
|
|
|
2007-02-13 20:26:26 +08:00
|
|
|
if (current->binfmt->hasvdso)
|
2008-01-30 20:30:42 +08:00
|
|
|
restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn);
|
2007-02-13 20:26:26 +08:00
|
|
|
else
|
2008-01-30 20:33:23 +08:00
|
|
|
restorer = &frame->retcode;
|
2005-04-17 06:20:36 +08:00
|
|
|
if (ka->sa.sa_flags & SA_RESTORER)
|
|
|
|
|
restorer = ka->sa.sa_restorer;
|
|
|
|
|
|
|
|
|
|
/* Set up to return from userspace. */
|
|
|
|
|
err |= __put_user(restorer, &frame->pretcode);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* 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)
|
|
|
|
|
goto give_sigsegv;
|
|
|
|
|
|
|
|
|
|
/* Set up registers for signal handler */
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->sp = (unsigned long) frame;
|
|
|
|
|
regs->ip = (unsigned long) ka->sa.sa_handler;
|
|
|
|
|
regs->ax = (unsigned long) sig;
|
|
|
|
|
regs->dx = (unsigned long) 0;
|
|
|
|
|
regs->cx = (unsigned long) 0;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->ds = __USER_DS;
|
|
|
|
|
regs->es = __USER_DS;
|
|
|
|
|
regs->ss = __USER_DS;
|
|
|
|
|
regs->cs = __USER_CS;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Clear TF when entering the signal handler, but
|
|
|
|
|
* notify any tracer that was single-stepping it.
|
|
|
|
|
* The tracer may want to single-step inside the
|
|
|
|
|
* handler too.
|
|
|
|
|
*/
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->flags &= ~TF_MASK;
|
2005-04-17 06:20:36 +08:00
|
|
|
if (test_thread_flag(TIF_SINGLESTEP))
|
|
|
|
|
ptrace_notify(SIGTRAP);
|
|
|
|
|
|
|
|
|
|
#if DEBUG_SIG
|
|
|
|
|
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
|
2008-01-30 20:30:56 +08:00
|
|
|
current->comm, current->pid, frame, regs->ip, frame->pretcode);
|
2005-04-17 06:20:36 +08:00
|
|
|
#endif
|
|
|
|
|
|
2006-01-19 09:44:00 +08:00
|
|
|
return 0;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
give_sigsegv:
|
|
|
|
|
force_sigsegv(sig, current);
|
2006-01-19 09:44:00 +08:00
|
|
|
return -EFAULT;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
2005-06-23 15:08:21 +08:00
|
|
|
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
|
2005-04-17 06:20:36 +08:00
|
|
|
sigset_t *set, struct pt_regs * regs)
|
|
|
|
|
{
|
|
|
|
|
void __user *restorer;
|
|
|
|
|
struct rt_sigframe __user *frame;
|
|
|
|
|
int err = 0;
|
|
|
|
|
int usig;
|
|
|
|
|
|
|
|
|
|
frame = get_sigframe(ka, regs, sizeof(*frame));
|
|
|
|
|
|
|
|
|
|
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
|
|
|
|
|
goto give_sigsegv;
|
|
|
|
|
|
|
|
|
|
usig = 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(usig, &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);
|
2008-01-30 20:30:56 +08:00
|
|
|
err |= __put_user(sas_ss_flags(regs->sp),
|
2005-04-17 06:20:36 +08:00
|
|
|
&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. */
|
2008-01-30 20:30:42 +08:00
|
|
|
restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn);
|
2005-04-17 06:20:36 +08:00
|
|
|
if (ka->sa.sa_flags & SA_RESTORER)
|
|
|
|
|
restorer = ka->sa.sa_restorer;
|
|
|
|
|
err |= __put_user(restorer, &frame->pretcode);
|
|
|
|
|
|
|
|
|
|
/*
|
2008-01-30 20:30:56 +08:00
|
|
|
* This is movl $,%ax ; int $0x80
|
2005-04-17 06:20:36 +08:00
|
|
|
*
|
|
|
|
|
* 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)
|
|
|
|
|
goto give_sigsegv;
|
|
|
|
|
|
|
|
|
|
/* Set up registers for signal handler */
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->sp = (unsigned long) frame;
|
|
|
|
|
regs->ip = (unsigned long) ka->sa.sa_handler;
|
|
|
|
|
regs->ax = (unsigned long) usig;
|
|
|
|
|
regs->dx = (unsigned long) &frame->info;
|
|
|
|
|
regs->cx = (unsigned long) &frame->uc;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->ds = __USER_DS;
|
|
|
|
|
regs->es = __USER_DS;
|
|
|
|
|
regs->ss = __USER_DS;
|
|
|
|
|
regs->cs = __USER_CS;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Clear TF when entering the signal handler, but
|
|
|
|
|
* notify any tracer that was single-stepping it.
|
|
|
|
|
* The tracer may want to single-step inside the
|
|
|
|
|
* handler too.
|
|
|
|
|
*/
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->flags &= ~TF_MASK;
|
2005-04-17 06:20:36 +08:00
|
|
|
if (test_thread_flag(TIF_SINGLESTEP))
|
|
|
|
|
ptrace_notify(SIGTRAP);
|
|
|
|
|
|
|
|
|
|
#if DEBUG_SIG
|
|
|
|
|
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
|
2008-01-30 20:30:56 +08:00
|
|
|
current->comm, current->pid, frame, regs->ip, frame->pretcode);
|
2005-04-17 06:20:36 +08:00
|
|
|
#endif
|
|
|
|
|
|
2006-01-19 09:44:00 +08:00
|
|
|
return 0;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
give_sigsegv:
|
|
|
|
|
force_sigsegv(sig, current);
|
2006-01-19 09:44:00 +08:00
|
|
|
return -EFAULT;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* OK, we're invoking a handler
|
|
|
|
|
*/
|
|
|
|
|
|
2005-06-23 15:08:21 +08:00
|
|
|
static int
|
2005-04-17 06:20:36 +08:00
|
|
|
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
|
|
|
|
|
sigset_t *oldset, struct pt_regs * regs)
|
|
|
|
|
{
|
2005-06-23 15:08:21 +08:00
|
|
|
int ret;
|
|
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
/* Are we from a system call? */
|
2008-01-30 20:30:56 +08:00
|
|
|
if (regs->orig_ax >= 0) {
|
2005-04-17 06:20:36 +08:00
|
|
|
/* If so, check system call restarting.. */
|
2008-01-30 20:30:56 +08:00
|
|
|
switch (regs->ax) {
|
2005-04-17 06:20:36 +08:00
|
|
|
case -ERESTART_RESTARTBLOCK:
|
|
|
|
|
case -ERESTARTNOHAND:
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->ax = -EINTR;
|
2005-04-17 06:20:36 +08:00
|
|
|
break;
|
|
|
|
|
|
|
|
|
|
case -ERESTARTSYS:
|
|
|
|
|
if (!(ka->sa.sa_flags & SA_RESTART)) {
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->ax = -EINTR;
|
2005-04-17 06:20:36 +08:00
|
|
|
break;
|
|
|
|
|
}
|
|
|
|
|
/* fallthrough */
|
|
|
|
|
case -ERESTARTNOINTR:
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->ax = regs->orig_ax;
|
|
|
|
|
regs->ip -= 2;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
2008-01-30 20:30:50 +08:00
|
|
|
* If TF is set due to a debugger (TIF_FORCED_TF), clear the TF
|
|
|
|
|
* flag so that register information in the sigcontext is correct.
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
2008-01-30 20:30:56 +08:00
|
|
|
if (unlikely(regs->flags & X86_EFLAGS_TF) &&
|
2008-01-30 20:30:50 +08:00
|
|
|
likely(test_and_clear_thread_flag(TIF_FORCED_TF)))
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->flags &= ~X86_EFLAGS_TF;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
/* Set up the stack frame */
|
|
|
|
|
if (ka->sa.sa_flags & SA_SIGINFO)
|
2005-06-23 15:08:21 +08:00
|
|
|
ret = setup_rt_frame(sig, ka, info, oldset, regs);
|
2005-04-17 06:20:36 +08:00
|
|
|
else
|
2005-06-23 15:08:21 +08:00
|
|
|
ret = setup_frame(sig, ka, oldset, regs);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2006-01-19 09:44:00 +08:00
|
|
|
if (ret == 0) {
|
2005-04-17 06:20:36 +08:00
|
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
|
|
|
sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask);
|
[PATCH] convert signal handling of NODEFER to act like other Unix boxes.
It has been reported that the way Linux handles NODEFER for signals is
not consistent with the way other Unix boxes handle it. I've written a
program to test the behavior of how this flag affects signals and had
several reports from people who ran this on various Unix boxes,
confirming that Linux seems to be unique on the way this is handled.
The way NODEFER affects signals on other Unix boxes is as follows:
1) If NODEFER is set, other signals in sa_mask are still blocked.
2) If NODEFER is set and the signal is in sa_mask, then the signal is
still blocked. (Note: this is the behavior of all tested but Linux _and_
NetBSD 2.0 *).
The way NODEFER affects signals on Linux:
1) If NODEFER is set, other signals are _not_ blocked regardless of
sa_mask (Even NetBSD doesn't do this).
2) If NODEFER is set and the signal is in sa_mask, then the signal being
handled is not blocked.
The patch converts signal handling in all current Linux architectures to
the way most Unix boxes work.
Unix boxes that were tested: DU4, AIX 5.2, Irix 6.5, NetBSD 2.0, SFU
3.5 on WinXP, AIX 5.3, Mac OSX, and of course Linux 2.6.13-rcX.
* NetBSD was the only other Unix to behave like Linux on point #2. The
main concern was brought up by point #1 which even NetBSD isn't like
Linux. So with this patch, we leave NetBSD as the lonely one that
behaves differently here with #2.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-08-29 23:44:09 +08:00
|
|
|
if (!(ka->sa.sa_flags & SA_NODEFER))
|
|
|
|
|
sigaddset(¤t->blocked,sig);
|
2005-04-17 06:20:36 +08:00
|
|
|
recalc_sigpending();
|
|
|
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
|
|
|
}
|
2005-06-23 15:08:21 +08:00
|
|
|
|
|
|
|
|
return ret;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* 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.
|
|
|
|
|
*/
|
2008-01-30 20:31:17 +08:00
|
|
|
static void do_signal(struct pt_regs *regs)
|
2005-04-17 06:20:36 +08:00
|
|
|
{
|
|
|
|
|
siginfo_t info;
|
|
|
|
|
int signr;
|
|
|
|
|
struct k_sigaction ka;
|
2006-01-19 09:44:00 +08:00
|
|
|
sigset_t *oldset;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* 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
|
2005-09-04 06:56:43 +08:00
|
|
|
* if so. vm86 regs switched out by assembly code
|
|
|
|
|
* before reaching here, so testing against kernel
|
|
|
|
|
* CS suffices.
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
2005-06-23 15:08:45 +08:00
|
|
|
if (!user_mode(regs))
|
2006-01-19 09:44:00 +08:00
|
|
|
return;
|
2005-04-17 06:20:36 +08:00
|
|
|
|
2006-01-19 09:44:00 +08:00
|
|
|
if (test_thread_flag(TIF_RESTORE_SIGMASK))
|
|
|
|
|
oldset = ¤t->saved_sigmask;
|
|
|
|
|
else
|
2005-04-17 06:20:36 +08:00
|
|
|
oldset = ¤t->blocked;
|
|
|
|
|
|
|
|
|
|
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
|
|
|
|
|
if (signr > 0) {
|
2007-10-20 07:13:56 +08:00
|
|
|
/* Re-enable any watchpoints before delivering the
|
2005-04-17 06:20:36 +08:00
|
|
|
* signal to user space. The processor register will
|
|
|
|
|
* have been cleared if the watchpoint triggered
|
|
|
|
|
* inside the kernel.
|
|
|
|
|
*/
|
2008-01-30 20:30:59 +08:00
|
|
|
if (unlikely(current->thread.debugreg7))
|
|
|
|
|
set_debugreg(current->thread.debugreg7, 7);
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
/* Whee! Actually deliver the signal. */
|
2006-01-19 09:44:00 +08:00
|
|
|
if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
|
|
|
|
|
/* a signal was successfully delivered; the saved
|
|
|
|
|
* sigmask will have been stored in the signal frame,
|
|
|
|
|
* and will be restored by sigreturn, so we can simply
|
|
|
|
|
* clear the TIF_RESTORE_SIGMASK flag */
|
|
|
|
|
if (test_thread_flag(TIF_RESTORE_SIGMASK))
|
|
|
|
|
clear_thread_flag(TIF_RESTORE_SIGMASK);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/* Did we come from a system call? */
|
2008-01-30 20:30:56 +08:00
|
|
|
if (regs->orig_ax >= 0) {
|
2005-04-17 06:20:36 +08:00
|
|
|
/* Restart the system call - no handlers present */
|
2008-01-30 20:30:56 +08:00
|
|
|
switch (regs->ax) {
|
2006-01-19 09:44:00 +08:00
|
|
|
case -ERESTARTNOHAND:
|
|
|
|
|
case -ERESTARTSYS:
|
|
|
|
|
case -ERESTARTNOINTR:
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->ax = regs->orig_ax;
|
|
|
|
|
regs->ip -= 2;
|
2006-01-19 09:44:00 +08:00
|
|
|
break;
|
|
|
|
|
|
|
|
|
|
case -ERESTART_RESTARTBLOCK:
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->ax = __NR_restart_syscall;
|
|
|
|
|
regs->ip -= 2;
|
2006-01-19 09:44:00 +08:00
|
|
|
break;
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
}
|
2006-01-19 09:44:00 +08:00
|
|
|
|
|
|
|
|
/* if there's no signal to deliver, we just put the saved sigmask
|
|
|
|
|
* back */
|
|
|
|
|
if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
|
|
|
|
|
clear_thread_flag(TIF_RESTORE_SIGMASK);
|
|
|
|
|
sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
|
|
|
|
|
}
|
2005-04-17 06:20:36 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* notification of userspace execution resumption
|
2006-01-19 09:44:00 +08:00
|
|
|
* - triggered by the TIF_WORK_MASK flags
|
2005-04-17 06:20:36 +08:00
|
|
|
*/
|
|
|
|
|
__attribute__((regparm(3)))
|
2006-01-19 09:44:00 +08:00
|
|
|
void do_notify_resume(struct pt_regs *regs, void *_unused,
|
2005-04-17 06:20:36 +08:00
|
|
|
__u32 thread_info_flags)
|
|
|
|
|
{
|
|
|
|
|
/* Pending single-step? */
|
|
|
|
|
if (thread_info_flags & _TIF_SINGLESTEP) {
|
2008-01-30 20:30:56 +08:00
|
|
|
regs->flags |= TF_MASK;
|
2005-04-17 06:20:36 +08:00
|
|
|
clear_thread_flag(TIF_SINGLESTEP);
|
|
|
|
|
}
|
2006-01-19 09:44:00 +08:00
|
|
|
|
2005-04-17 06:20:36 +08:00
|
|
|
/* deal with pending signal delivery */
|
2006-01-19 09:44:00 +08:00
|
|
|
if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
|
|
|
|
|
do_signal(regs);
|
2008-01-26 04:08:29 +08:00
|
|
|
|
|
|
|
|
if (thread_info_flags & _TIF_HRTICK_RESCHED)
|
|
|
|
|
hrtick_resched();
|
2005-04-17 06:20:36 +08:00
|
|
|
|
|
|
|
|
clear_thread_flag(TIF_IRET);
|
|
|
|
|
}
|