/* * 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/list.h> #include <linux/personality.h> #include <linux/binfmts.h> #include <linux/suspend.h> #include <linux/kernel.h> #include <linux/ptrace.h> #include <linux/signal.h> #include <linux/stddef.h> #include <linux/unistd.h> #include <linux/errno.h> #include <linux/sched.h> #include <linux/wait.h> #include <linux/elf.h> #include <linux/smp.h> #include <linux/mm.h> #include <asm/processor.h> #include <asm/ucontext.h> #include <asm/uaccess.h> #include <asm/i387.h> #include <asm/vdso.h> #include "sigframe.h" #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) #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) #ifdef CONFIG_X86_32 # define FIX_EFLAGS (__FIX_EFLAGS | X86_EFLAGS_RF) #else # define FIX_EFLAGS __FIX_EFLAGS #endif /* * Atomically swap in the new signal mask, and wait for a signal. */ asmlinkage int sys_sigsuspend(int history0, int history1, old_sigset_t mask) { mask &= _BLOCKABLE; spin_lock_irq(¤t->sighand->siglock); current->saved_sigmask = current->blocked; siginitset(¤t->blocked, mask); recalc_sigpending(); spin_unlock_irq(¤t->sighand->siglock); current->state = TASK_INTERRUPTIBLE; schedule(); set_restore_sigmask(); return -ERESTARTNOHAND; } 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 bx) { /* * This is needed to make gcc realize it doesn't own the * "struct pt_regs" */ struct pt_regs *regs = (struct pt_regs *)&bx; const stack_t __user *uss = (const stack_t __user *)bx; stack_t __user *uoss = (stack_t __user *)regs->cx; return do_sigaltstack(uss, uoss, regs->sp); } /* * Do a signal return; undo the signal stack. */ static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *pax) { 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->seg = tmp; } #define COPY_SEG_STRICT(seg) \ { unsigned short tmp; \ err |= __get_user(tmp, &sc->seg); \ regs->seg = tmp|3; } #define GET_SEG(seg) \ { unsigned short tmp; \ err |= __get_user(tmp, &sc->seg); \ loadsegment(seg, tmp); } GET_SEG(gs); COPY_SEG(fs); COPY_SEG(es); COPY_SEG(ds); COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); COPY(dx); COPY(cx); COPY(ip); COPY_SEG_STRICT(cs); COPY_SEG_STRICT(ss); { unsigned int tmpflags; err |= __get_user(tmpflags, &sc->flags); regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); regs->orig_ax = -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(*pax, &sc->ax); return err; badframe: return 1; } asmlinkage unsigned long sys_sigreturn(unsigned long __unused) { struct sigframe __user *frame; struct pt_regs *regs; unsigned long ax; sigset_t set; regs = (struct pt_regs *) &__unused; frame = (struct sigframe __user *)(regs->sp - 8); 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, &ax)) goto badframe; return ax; badframe: if (show_unhandled_signals && printk_ratelimit()) { printk(KERN_INFO "%s%s[%d] bad frame in sigreturn frame:" "%p ip:%lx sp:%lx oeax:%lx", task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, current->comm, task_pid_nr(current), frame, regs->ip, regs->sp, regs->orig_ax); print_vma_addr(" in ", regs->ip); printk(KERN_CONT "\n"); } 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; unsigned long ax; sigset_t set; frame = (struct rt_sigframe __user *)(regs->sp - sizeof(long)); 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, &ax)) goto badframe; if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) goto badframe; return ax; 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; err |= __put_user(regs->fs, (unsigned int __user *)&sc->fs); savesegment(gs, tmp); err |= __put_user(tmp, (unsigned int __user *)&sc->gs); err |= __put_user(regs->es, (unsigned int __user *)&sc->es); err |= __put_user(regs->ds, (unsigned int __user *)&sc->ds); err |= __put_user(regs->di, &sc->di); err |= __put_user(regs->si, &sc->si); err |= __put_user(regs->bp, &sc->bp); err |= __put_user(regs->sp, &sc->sp); err |= __put_user(regs->bx, &sc->bx); err |= __put_user(regs->dx, &sc->dx); err |= __put_user(regs->cx, &sc->cx); err |= __put_user(regs->ax, &sc->ax); err |= __put_user(current->thread.trap_no, &sc->trapno); err |= __put_user(current->thread.error_code, &sc->err); err |= __put_user(regs->ip, &sc->ip); err |= __put_user(regs->cs, (unsigned int __user *)&sc->cs); err |= __put_user(regs->flags, &sc->flags); err |= __put_user(regs->sp, &sc->sp_at_signal); err |= __put_user(regs->ss, (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 sp; /* Default to using normal stack */ sp = regs->sp; /* * 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. */ if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size))) return (void __user *) -1L; /* This is the X/Open sanctioned signal stack switching. */ if (ka->sa.sa_flags & SA_ONSTACK) { if (sas_ss_flags(sp) == 0) sp = current->sas_ss_sp + current->sas_ss_size; } else { /* This is the legacy signal stack switching. */ if ((regs->ss & 0xffff) != __USER_DS && !(ka->sa.sa_flags & SA_RESTORER) && ka->sa.sa_restorer) sp = (unsigned long) ka->sa.sa_restorer; } sp -= frame_size; /* * Align the stack pointer according to the i386 ABI, * i.e. so that on function entry ((sp + 4) & 15) == 0. */ sp = ((sp + 4) & -16ul) - 4; return (void __user *) sp; } static int setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs) { struct sigframe __user *frame; void __user *restorer; 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; } if (current->mm->context.vdso) restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn); else restorer = &frame->retcode; 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 $__NR_sigreturn, %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->sp = (unsigned long)frame; regs->ip = (unsigned long)ka->sa.sa_handler; regs->ax = (unsigned long)sig; regs->dx = 0; regs->cx = 0; regs->ds = __USER_DS; regs->es = __USER_DS; regs->ss = __USER_DS; regs->cs = __USER_CS; return 0; give_sigsegv: force_sigsegv(sig, current); return -EFAULT; } static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe __user *frame; void __user *restorer; 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->sp), &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 = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn); if (ka->sa.sa_flags & SA_RESTORER) restorer = ka->sa.sa_restorer; err |= __put_user(restorer, &frame->pretcode); /* * This is movl $__NR_rt_sigreturn, %ax ; 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->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; regs->ds = __USER_DS; regs->es = __USER_DS; regs->ss = __USER_DS; regs->cs = __USER_CS; return 0; give_sigsegv: force_sigsegv(sig, current); return -EFAULT; } /* * 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 ((long)regs->orig_ax >= 0) { /* If so, check system call restarting.. */ switch (regs->ax) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: regs->ax = -EINTR; break; case -ERESTARTSYS: if (!(ka->sa.sa_flags & SA_RESTART)) { regs->ax = -EINTR; break; } /* fallthrough */ case -ERESTARTNOINTR: regs->ax = regs->orig_ax; regs->ip -= 2; break; } } /* * If TF is set due to a debugger (TIF_FORCED_TF), clear the TF * flag so that register information in the sigcontext is correct. */ if (unlikely(regs->flags & X86_EFLAGS_TF) && likely(test_and_clear_thread_flag(TIF_FORCED_TF))) regs->flags &= ~X86_EFLAGS_TF; /* 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) return ret; /* * Clear the direction flag as per the ABI for function entry. */ regs->flags &= ~X86_EFLAGS_DF; /* * 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->flags &= ~X86_EFLAGS_TF; if (test_thread_flag(TIF_SINGLESTEP)) ptrace_notify(SIGTRAP); 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 0; } /* * 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. */ static void do_signal(struct pt_regs *regs) { struct k_sigaction ka; siginfo_t info; int signr; sigset_t *oldset; /* * 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. * X86_32: vm86 regs switched out by assembly code before reaching * here, so testing against kernel CS suffices. */ if (!user_mode(regs)) return; if (current_thread_info()->status & TS_RESTORE_SIGMASK) oldset = ¤t->saved_sigmask; else oldset = ¤t->blocked; signr = get_signal_to_deliver(&info, &ka, regs, NULL); if (signr > 0) { /* * Re-enable any watchpoints before delivering the * signal to user space. The processor register will * have been cleared if the watchpoint triggered * inside the kernel. */ if (current->thread.debugreg7) set_debugreg(current->thread.debugreg7, 7); /* Whee! Actually deliver the signal. */ 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 TS_RESTORE_SIGMASK flag. */ current_thread_info()->status &= ~TS_RESTORE_SIGMASK; } return; } /* Did we come from a system call? */ if ((long)regs->orig_ax >= 0) { /* Restart the system call - no handlers present */ switch (regs->ax) { case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: regs->ax = regs->orig_ax; regs->ip -= 2; break; case -ERESTART_RESTARTBLOCK: regs->ax = __NR_restart_syscall; regs->ip -= 2; break; } } /* * If there's no signal to deliver, we just put the saved sigmask * back. */ if (current_thread_info()->status & TS_RESTORE_SIGMASK) { current_thread_info()->status &= ~TS_RESTORE_SIGMASK; sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); } } /* * notification of userspace execution resumption * - triggered by the TIF_WORK_MASK flags */ void do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) { /* Pending single-step? */ if (thread_info_flags & _TIF_SINGLESTEP) { regs->flags |= X86_EFLAGS_TF; clear_thread_flag(TIF_SINGLESTEP); } /* deal with pending signal delivery */ if (thread_info_flags & _TIF_SIGPENDING) do_signal(regs); if (thread_info_flags & _TIF_HRTICK_RESCHED) hrtick_resched(); clear_thread_flag(TIF_IRET); }