/* * 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/unistd.h> #include <linux/stddef.h> #include <linux/personality.h> #include <linux/suspend.h> #include <linux/ptrace.h> #include <linux/elf.h> #include <asm/processor.h> #include <asm/ucontext.h> #include <asm/uaccess.h> #include <asm/i387.h> #include "sigframe.h" #define DEBUG_SIG 0 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) /* * 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->sighand->siglock); saveset = current->blocked; siginitset(¤t->blocked, mask); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); regs->eax = -EINTR; while (1) { current->state = TASK_INTERRUPTIBLE; schedule(); if (do_signal(regs, &saveset)) return -EINTR; } } asmlinkage int sys_rt_sigsuspend(struct pt_regs regs) { sigset_t saveset, newset; /* XXX: Don't preclude handling different sized sigset_t's. */ if (regs.ecx != sizeof(sigset_t)) return -EINVAL; if (copy_from_user(&newset, (sigset_t __user *)regs.ebx, sizeof(newset))) return -EFAULT; sigdelsetmask(&newset, ~_BLOCKABLE); spin_lock_irq(¤t->sighand->siglock); saveset = current->blocked; current->blocked = newset; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); regs.eax = -EINTR; while (1) { current->state = TASK_INTERRUPTIBLE; schedule(); if (do_signal(®s, &saveset)) return -EINTR; } } asmlinkage int sys_sigaction(int sig, const struct old_sigaction __user *act, struct old_sigaction __user *oact) { struct k_sigaction new_ka, old_ka; int ret; if (act) { old_sigset_t mask; if (!access_ok(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 (!access_ok(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(unsigned long ebx) { /* This is needed to make gcc realize it doesn't own the "struct pt_regs" */ struct pt_regs *regs = (struct pt_regs *)&ebx; const stack_t __user *uss = (const stack_t __user *)ebx; stack_t __user *uoss = (stack_t __user *)regs->ecx; return do_sigaltstack(uss, uoss, regs->esp); } /* * Do a signal return; undo the signal stack. */ static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *peax) { unsigned int err = 0; /* Always make any pending restarted system calls return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; #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); } #define FIX_EFLAGS (X86_EFLAGS_AC | X86_EFLAGS_OF | X86_EFLAGS_DF | \ X86_EFLAGS_TF | X86_EFLAGS_SF | X86_EFLAGS_ZF | \ X86_EFLAGS_AF | X86_EFLAGS_PF | X86_EFLAGS_CF) 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 & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); regs->orig_eax = -1; /* disable syscall checks */ } { struct _fpstate __user * buf; err |= __get_user(buf, &sc->fpstate); if (buf) { if (!access_ok(VERIFY_READ, buf, sizeof(*buf))) goto badframe; err |= restore_i387(buf); } else { struct task_struct *me = current; if (used_math()) { clear_fpu(me); clear_used_math(); } } } 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 __user *frame = (struct sigframe __user *)(regs->esp - 8); sigset_t set; int eax; if (!access_ok(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->sighand->siglock); current->blocked = set; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); 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 __user *frame = (struct rt_sigframe __user *)(regs->esp - 4); sigset_t set; int eax; if (!access_ok(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->sighand->siglock); current->blocked = set; recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax)) goto badframe; if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->esp) == -EFAULT) goto badframe; return eax; badframe: force_sig(SIGSEGV, current); return 0; } /* * Set up a signal frame. */ static int setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *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 __user *)&sc->gs); __asm__("movl %%fs,%0" : "=r"(tmp): "0"(tmp)); err |= __put_user(tmp, (unsigned int __user *)&sc->fs); err |= __put_user(regs->xes, (unsigned int __user *)&sc->es); err |= __put_user(regs->xds, (unsigned int __user *)&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 __user *)&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 __user *)&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 __user * 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 __user *)((esp - frame_size) & -8ul); } /* 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; static void setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, struct pt_regs * regs) { 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; } restorer = &__kernel_sigreturn; 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 */ regs->esp = (unsigned long) frame; regs->eip = (unsigned long) ka->sa.sa_handler; regs->eax = (unsigned long) sig; regs->edx = (unsigned long) 0; regs->ecx = (unsigned long) 0; 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; give_sigsegv: force_sigsegv(sig, current); } static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, 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); 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. */ restorer = &__kernel_rt_sigreturn; 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; give_sigsegv: force_sigsegv(sig, current); } /* * OK, we're invoking a handler */ static void handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka, 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 -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) setup_rt_frame(sig, ka, info, oldset, regs); else setup_frame(sig, ka, oldset, regs); if (!(ka->sa.sa_flags & SA_NODEFER)) { spin_lock_irq(¤t->sighand->siglock); sigorsets(¤t->blocked,¤t->blocked,&ka->sa.sa_mask); sigaddset(¤t->blocked,sig); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); } } /* * 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. */ if ((regs->xcs & 3) != 3) return 1; if (current->flags & PF_FREEZE) { refrigerator(0); 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])) { loaddebug(¤t->thread, 7); } /* Whee! Actually deliver the signal. */ handle_signal(signr, &info, &ka, oldset, regs); return 1; } 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); }