![Markus F.X.J. Oberhumer](/assets/img/avatar_default.png)
This fixes the setup of the alignment of the signal frame, so that all signal handlers are run with a properly aligned stack frame. The current code "over-aligns" the stack pointer so that the stack frame is effectively always mis-aligned by 4 bytes. But what we really want is that on function entry ((sp + 4) & 15) == 0, which matches what would happen if the stack were aligned before a "call" instruction. Signed-off-by: Markus F.X.J. Oberhumer <markus@oberhumer.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
676 lines
17 KiB
C
676 lines
17 KiB
C
/*
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* linux/arch/i386/kernel/signal.c
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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/smp_lock.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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#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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#include "sigframe.h"
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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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struct pt_regs * regs = (struct pt_regs *) &history0;
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sigset_t saveset;
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mask &= _BLOCKABLE;
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spin_lock_irq(¤t->sighand->siglock);
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saveset = current->blocked;
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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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regs->eax = -EINTR;
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while (1) {
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current->state = TASK_INTERRUPTIBLE;
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schedule();
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if (do_signal(regs, &saveset))
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return -EINTR;
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}
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}
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asmlinkage int
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sys_rt_sigsuspend(struct pt_regs regs)
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{
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sigset_t saveset, newset;
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/* XXX: Don't preclude handling different sized sigset_t's. */
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if (regs.ecx != sizeof(sigset_t))
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return -EINVAL;
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if (copy_from_user(&newset, (sigset_t __user *)regs.ebx, sizeof(newset)))
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return -EFAULT;
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sigdelsetmask(&newset, ~_BLOCKABLE);
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spin_lock_irq(¤t->sighand->siglock);
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saveset = current->blocked;
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current->blocked = newset;
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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regs.eax = -EINTR;
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while (1) {
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current->state = TASK_INTERRUPTIBLE;
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schedule();
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if (do_signal(®s, &saveset))
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return -EINTR;
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}
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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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sys_sigaltstack(unsigned long ebx)
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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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struct pt_regs *regs = (struct pt_regs *)&ebx;
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const stack_t __user *uss = (const stack_t __user *)ebx;
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stack_t __user *uoss = (stack_t __user *)regs->ecx;
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return do_sigaltstack(uss, uoss, regs->esp);
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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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#define COPY(x) err |= __get_user(regs->x, &sc->x)
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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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regs->x##seg = tmp; }
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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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regs->x##seg = tmp|3; }
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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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#define FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_OF | X86_EFLAGS_DF | \
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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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GET_SEG(gs);
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GET_SEG(fs);
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COPY_SEG(es);
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COPY_SEG(ds);
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COPY(edi);
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COPY(esi);
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COPY(ebp);
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COPY(esp);
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COPY(ebx);
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COPY(edx);
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COPY(ecx);
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COPY(eip);
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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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err |= __get_user(tmpflags, &sc->eflags);
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regs->eflags = (regs->eflags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
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regs->orig_eax = -1; /* disable syscall checks */
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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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err |= __get_user(*peax, &sc->eax);
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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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struct sigframe __user *frame = (struct sigframe __user *)(regs->esp - 8);
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sigset_t set;
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int eax;
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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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if (restore_sigcontext(regs, &frame->sc, &eax))
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goto badframe;
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return eax;
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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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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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struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(regs->esp - 4);
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sigset_t set;
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int eax;
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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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if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
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goto badframe;
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if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->esp) == -EFAULT)
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goto badframe;
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return eax;
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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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tmp = 0;
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savesegment(gs, tmp);
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err |= __put_user(tmp, (unsigned int __user *)&sc->gs);
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savesegment(fs, tmp);
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err |= __put_user(tmp, (unsigned int __user *)&sc->fs);
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err |= __put_user(regs->xes, (unsigned int __user *)&sc->es);
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err |= __put_user(regs->xds, (unsigned int __user *)&sc->ds);
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err |= __put_user(regs->edi, &sc->edi);
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err |= __put_user(regs->esi, &sc->esi);
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err |= __put_user(regs->ebp, &sc->ebp);
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err |= __put_user(regs->esp, &sc->esp);
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err |= __put_user(regs->ebx, &sc->ebx);
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err |= __put_user(regs->edx, &sc->edx);
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err |= __put_user(regs->ecx, &sc->ecx);
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err |= __put_user(regs->eax, &sc->eax);
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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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err |= __put_user(regs->eip, &sc->eip);
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err |= __put_user(regs->xcs, (unsigned int __user *)&sc->cs);
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err |= __put_user(regs->eflags, &sc->eflags);
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err |= __put_user(regs->esp, &sc->esp_at_signal);
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err |= __put_user(regs->xss, (unsigned int __user *)&sc->ss);
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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.. */
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err |= __put_user(mask, &sc->oldmask);
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err |= __put_user(current->thread.cr2, &sc->cr2);
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return err;
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}
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/*
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* Determine which stack to use..
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*/
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static inline void __user *
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get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
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{
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unsigned long esp;
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/* Default to using normal stack */
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esp = regs->esp;
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/* This is the X/Open sanctioned signal stack switching. */
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if (ka->sa.sa_flags & SA_ONSTACK) {
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if (sas_ss_flags(esp) == 0)
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esp = current->sas_ss_sp + current->sas_ss_size;
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}
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/* This is the legacy signal stack switching. */
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else if ((regs->xss & 0xffff) != __USER_DS &&
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!(ka->sa.sa_flags & SA_RESTORER) &&
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ka->sa.sa_restorer) {
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esp = (unsigned long) ka->sa.sa_restorer;
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}
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esp -= frame_size;
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/* Align the stack pointer according to the i386 ABI,
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* i.e. so that on function entry ((sp + 4) & 15) == 0. */
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esp = ((esp + 4) & -16ul) - 4;
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return (void __user *) esp;
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}
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/* These symbols are defined with the addresses in the vsyscall page.
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See vsyscall-sigreturn.S. */
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extern void __user __kernel_sigreturn;
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extern void __user __kernel_rt_sigreturn;
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static int setup_frame(int sig, struct k_sigaction *ka,
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sigset_t *set, struct pt_regs * regs)
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{
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void __user *restorer;
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struct sigframe __user *frame;
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int err = 0;
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int usig;
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frame = get_sigframe(ka, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
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goto give_sigsegv;
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usig = current_thread_info()->exec_domain
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&& current_thread_info()->exec_domain->signal_invmap
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&& sig < 32
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? current_thread_info()->exec_domain->signal_invmap[sig]
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: sig;
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err = __put_user(usig, &frame->sig);
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if (err)
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goto give_sigsegv;
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err = setup_sigcontext(&frame->sc, &frame->fpstate, regs, set->sig[0]);
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if (err)
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goto give_sigsegv;
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if (_NSIG_WORDS > 1) {
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err = __copy_to_user(&frame->extramask, &set->sig[1],
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sizeof(frame->extramask));
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if (err)
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goto give_sigsegv;
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}
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restorer = &__kernel_sigreturn;
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if (ka->sa.sa_flags & SA_RESTORER)
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restorer = ka->sa.sa_restorer;
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/* Set up to return from userspace. */
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err |= __put_user(restorer, &frame->pretcode);
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/*
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* This is popl %eax ; movl $,%eax ; int $0x80
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*
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* WE DO NOT USE IT ANY MORE! It's only left here for historical
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* reasons and because gdb uses it as a signature to notice
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* signal handler stack frames.
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*/
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err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
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err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
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err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
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if (err)
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goto give_sigsegv;
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/* Set up registers for signal handler */
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regs->esp = (unsigned long) frame;
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regs->eip = (unsigned long) ka->sa.sa_handler;
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regs->eax = (unsigned long) sig;
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regs->edx = (unsigned long) 0;
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regs->ecx = (unsigned long) 0;
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set_fs(USER_DS);
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regs->xds = __USER_DS;
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regs->xes = __USER_DS;
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regs->xss = __USER_DS;
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regs->xcs = __USER_CS;
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/*
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* Clear TF when entering the signal handler, but
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* notify any tracer that was single-stepping it.
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* The tracer may want to single-step inside the
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* handler too.
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*/
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regs->eflags &= ~TF_MASK;
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if (test_thread_flag(TIF_SINGLESTEP))
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ptrace_notify(SIGTRAP);
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#if DEBUG_SIG
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printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
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current->comm, current->pid, frame, regs->eip, frame->pretcode);
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#endif
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return 1;
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give_sigsegv:
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force_sigsegv(sig, current);
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return 0;
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}
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static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
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sigset_t *set, struct pt_regs * regs)
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{
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void __user *restorer;
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struct rt_sigframe __user *frame;
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int err = 0;
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int usig;
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frame = get_sigframe(ka, regs, sizeof(*frame));
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if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
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goto give_sigsegv;
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usig = current_thread_info()->exec_domain
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&& current_thread_info()->exec_domain->signal_invmap
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&& sig < 32
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? current_thread_info()->exec_domain->signal_invmap[sig]
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: sig;
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err |= __put_user(usig, &frame->sig);
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err |= __put_user(&frame->info, &frame->pinfo);
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err |= __put_user(&frame->uc, &frame->puc);
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err |= copy_siginfo_to_user(&frame->info, info);
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if (err)
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goto give_sigsegv;
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/* Create the ucontext. */
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err |= __put_user(0, &frame->uc.uc_flags);
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err |= __put_user(0, &frame->uc.uc_link);
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err |= __put_user(current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
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err |= __put_user(sas_ss_flags(regs->esp),
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&frame->uc.uc_stack.ss_flags);
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err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
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err |= setup_sigcontext(&frame->uc.uc_mcontext, &frame->fpstate,
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regs, set->sig[0]);
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err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
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if (err)
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goto give_sigsegv;
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/* Set up to return from userspace. */
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restorer = &__kernel_rt_sigreturn;
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if (ka->sa.sa_flags & SA_RESTORER)
|
|
restorer = ka->sa.sa_restorer;
|
|
err |= __put_user(restorer, &frame->pretcode);
|
|
|
|
/*
|
|
* 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)
|
|
goto give_sigsegv;
|
|
|
|
/* Set up registers for signal handler */
|
|
regs->esp = (unsigned long) frame;
|
|
regs->eip = (unsigned long) ka->sa.sa_handler;
|
|
regs->eax = (unsigned long) usig;
|
|
regs->edx = (unsigned long) &frame->info;
|
|
regs->ecx = (unsigned long) &frame->uc;
|
|
|
|
set_fs(USER_DS);
|
|
regs->xds = __USER_DS;
|
|
regs->xes = __USER_DS;
|
|
regs->xss = __USER_DS;
|
|
regs->xcs = __USER_CS;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
regs->eflags &= ~TF_MASK;
|
|
if (test_thread_flag(TIF_SINGLESTEP))
|
|
ptrace_notify(SIGTRAP);
|
|
|
|
#if DEBUG_SIG
|
|
printk("SIG deliver (%s:%d): sp=%p pc=%p ra=%p\n",
|
|
current->comm, current->pid, frame, regs->eip, frame->pretcode);
|
|
#endif
|
|
|
|
return 1;
|
|
|
|
give_sigsegv:
|
|
force_sigsegv(sig, current);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* OK, we're invoking a handler
|
|
*/
|
|
|
|
static int
|
|
handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
|
|
sigset_t *oldset, struct pt_regs * regs)
|
|
{
|
|
int ret;
|
|
|
|
/* Are we from a system call? */
|
|
if (regs->orig_eax >= 0) {
|
|
/* If so, check system call restarting.. */
|
|
switch (regs->eax) {
|
|
case -ERESTART_RESTARTBLOCK:
|
|
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;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If TF is set due to a debugger (PT_DTRACE), clear the TF flag so
|
|
* that register information in the sigcontext is correct.
|
|
*/
|
|
if (unlikely(regs->eflags & TF_MASK)
|
|
&& likely(current->ptrace & PT_DTRACE)) {
|
|
current->ptrace &= ~PT_DTRACE;
|
|
regs->eflags &= ~TF_MASK;
|
|
}
|
|
|
|
/* Set up the stack frame */
|
|
if (ka->sa.sa_flags & SA_SIGINFO)
|
|
ret = setup_rt_frame(sig, ka, info, oldset, regs);
|
|
else
|
|
ret = setup_frame(sig, ka, oldset, regs);
|
|
|
|
if (ret) {
|
|
spin_lock_irq(¤t->sighand->siglock);
|
|
sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask);
|
|
if (!(ka->sa.sa_flags & SA_NODEFER))
|
|
sigaddset(¤t->blocked,sig);
|
|
recalc_sigpending();
|
|
spin_unlock_irq(¤t->sighand->siglock);
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
/*
|
|
* 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 fastcall do_signal(struct pt_regs *regs, sigset_t *oldset)
|
|
{
|
|
siginfo_t info;
|
|
int signr;
|
|
struct k_sigaction ka;
|
|
|
|
/*
|
|
* We want the common case to go fast, which
|
|
* is why we may in certain cases get here from
|
|
* kernel mode. Just return without doing anything
|
|
* if so. vm86 regs switched out by assembly code
|
|
* before reaching here, so testing against kernel
|
|
* CS suffices.
|
|
*/
|
|
if (!user_mode(regs))
|
|
return 1;
|
|
|
|
if (try_to_freeze())
|
|
goto no_signal;
|
|
|
|
if (!oldset)
|
|
oldset = ¤t->blocked;
|
|
|
|
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
|
|
if (signr > 0) {
|
|
/* Reenable any watchpoints before delivering the
|
|
* signal to user space. The processor register will
|
|
* have been cleared if the watchpoint triggered
|
|
* inside the kernel.
|
|
*/
|
|
if (unlikely(current->thread.debugreg[7])) {
|
|
set_debugreg(current->thread.debugreg[7], 7);
|
|
}
|
|
|
|
/* Whee! Actually deliver the signal. */
|
|
return handle_signal(signr, &info, &ka, oldset, regs);
|
|
}
|
|
|
|
no_signal:
|
|
/* 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;
|
|
}
|
|
if (regs->eax == -ERESTART_RESTARTBLOCK){
|
|
regs->eax = __NR_restart_syscall;
|
|
regs->eip -= 2;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* notification of userspace execution resumption
|
|
* - triggered by current->work.notify_resume
|
|
*/
|
|
__attribute__((regparm(3)))
|
|
void do_notify_resume(struct pt_regs *regs, sigset_t *oldset,
|
|
__u32 thread_info_flags)
|
|
{
|
|
/* Pending single-step? */
|
|
if (thread_info_flags & _TIF_SINGLESTEP) {
|
|
regs->eflags |= TF_MASK;
|
|
clear_thread_flag(TIF_SINGLESTEP);
|
|
}
|
|
/* deal with pending signal delivery */
|
|
if (thread_info_flags & _TIF_SIGPENDING)
|
|
do_signal(regs,oldset);
|
|
|
|
clear_thread_flag(TIF_IRET);
|
|
}
|