/* * Copyright (C) 1991, 1992 Linus Torvalds * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs * * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes * 2000-2002 x86-64 support by Andi Kleen */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* #define DEBUG_SIG 1 */ #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 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs * regs); int ia32_setup_frame(int sig, struct k_sigaction *ka, sigset_t *set, struct pt_regs * regs); asmlinkage long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss, struct pt_regs *regs) { return do_sigaltstack(uss, uoss, regs->sp); } /* * Do a signal return; undo the signal stack. */ struct rt_sigframe { char __user *pretcode; struct ucontext uc; struct siginfo info; }; static int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax) { 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) COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); COPY(dx); COPY(cx); COPY(ip); COPY(r8); COPY(r9); COPY(r10); COPY(r11); COPY(r12); COPY(r13); COPY(r14); COPY(r15); /* Kernel saves and restores only the CS segment register on signals, * which is the bare minimum needed to allow mixed 32/64-bit code. * App's signal handler can save/restore other segments if needed. */ { unsigned cs; err |= __get_user(cs, &sc->cs); regs->cs = cs | 3; /* Force into user mode */ } { 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(*prax, &sc->ax); return err; badframe: return 1; } asmlinkage long sys_rt_sigreturn(struct pt_regs *regs) { struct rt_sigframe __user *frame; sigset_t set; unsigned long ax; frame = (struct rt_sigframe __user *)(regs->sp - 8); 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; #ifdef DEBUG_SIG printk("%d sigreturn ip:%lx sp:%lx frame:%p ax:%lx\n",current->pid,regs->ip,regs->sp,frame,ax); #endif if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->sp) == -EFAULT) goto badframe; return ax; badframe: signal_fault(regs,frame,"sigreturn"); return 0; } /* * Set up a signal frame. */ static inline int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me) { int err = 0; err |= __put_user(regs->cs, &sc->cs); err |= __put_user(0, &sc->gs); err |= __put_user(0, &sc->fs); 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(regs->r8, &sc->r8); err |= __put_user(regs->r9, &sc->r9); err |= __put_user(regs->r10, &sc->r10); err |= __put_user(regs->r11, &sc->r11); err |= __put_user(regs->r12, &sc->r12); err |= __put_user(regs->r13, &sc->r13); err |= __put_user(regs->r14, &sc->r14); err |= __put_user(regs->r15, &sc->r15); err |= __put_user(me->thread.trap_no, &sc->trapno); err |= __put_user(me->thread.error_code, &sc->err); err |= __put_user(regs->ip, &sc->ip); err |= __put_user(regs->flags, &sc->flags); err |= __put_user(mask, &sc->oldmask); err |= __put_user(me->thread.cr2, &sc->cr2); return err; } /* * Determine which stack to use.. */ static void __user * get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size) { unsigned long sp; /* Default to using normal stack - redzone*/ sp = regs->sp - 128; /* 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; } return (void __user *)round_down(sp - size, 16); } 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; struct _fpstate __user *fp = NULL; int err = 0; struct task_struct *me = current; if (used_math()) { fp = get_stack(ka, regs, sizeof(struct _fpstate)); frame = (void __user *)round_down( (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8; if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate))) goto give_sigsegv; if (save_i387(fp) < 0) err |= -1; } else frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8; if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) goto give_sigsegv; if (ka->sa.sa_flags & SA_SIGINFO) { 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(me->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(me->sas_ss_size, &frame->uc.uc_stack.ss_size); err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me); err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate); if (sizeof(*set) == 16) { __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]); __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]); } else err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); /* Set up to return from userspace. If provided, use a stub already in userspace. */ /* x86-64 should always use SA_RESTORER. */ if (ka->sa.sa_flags & SA_RESTORER) { err |= __put_user(ka->sa.sa_restorer, &frame->pretcode); } else { /* could use a vstub here */ goto give_sigsegv; } if (err) goto give_sigsegv; #ifdef DEBUG_SIG printk("%d old ip %lx old sp %lx old ax %lx\n", current->pid,regs->ip,regs->sp,regs->ax); #endif /* Set up registers for signal handler */ regs->di = sig; /* In case the signal handler was declared without prototypes */ regs->ax = 0; /* This also works for non SA_SIGINFO handlers because they expect the next argument after the signal number on the stack. */ regs->si = (unsigned long)&frame->info; regs->dx = (unsigned long)&frame->uc; regs->ip = (unsigned long) ka->sa.sa_handler; regs->sp = (unsigned long)frame; /* Set up the CS register to run signal handlers in 64-bit mode, even if the handler happens to be interrupting 32-bit code. */ regs->cs = __USER_CS; /* This, by contrast, has nothing to do with segment registers - see include/asm-x86_64/uaccess.h for details. */ set_fs(USER_DS); regs->flags &= ~(X86_EFLAGS_TF | X86_EFLAGS_DF); if (test_thread_flag(TIF_SINGLESTEP)) ptrace_notify(SIGTRAP); #ifdef DEBUG_SIG printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%p\n", current->comm, current->pid, frame, regs->ip, frame->pretcode); #endif return 0; give_sigsegv: force_sigsegv(sig, current); return -EFAULT; } /* * Return -1L or the syscall number that @regs is executing. */ static long current_syscall(struct pt_regs *regs) { /* * We always sign-extend a -1 value being set here, * so this is always either -1L or a syscall number. */ return regs->orig_ax; } /* * Return a value that is -EFOO if the system call in @regs->orig_ax * returned an error. This only works for @regs from @current. */ static long current_syscall_ret(struct pt_regs *regs) { #ifdef CONFIG_IA32_EMULATION if (test_thread_flag(TIF_IA32)) /* * Sign-extend the value so (int)-EFOO becomes (long)-EFOO * and will match correctly in comparisons. */ return (int) regs->ax; #endif return regs->ax; } /* * 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; #ifdef DEBUG_SIG printk("handle_signal pid:%d sig:%lu ip:%lx sp:%lx regs=%p\n", current->pid, sig, regs->ip, regs->sp, regs); #endif /* Are we from a system call? */ if (current_syscall(regs) >= 0) { /* If so, check system call restarting.. */ switch (current_syscall_ret(regs)) { 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; #ifdef CONFIG_IA32_EMULATION if (test_thread_flag(TIF_IA32)) { if (ka->sa.sa_flags & SA_SIGINFO) ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs); else ret = ia32_setup_frame(sig, ka, oldset, regs); } else #endif ret = setup_rt_frame(sig, ka, info, oldset, regs); if (ret == 0) { 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. */ 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 (test_thread_flag(TIF_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 TIF_RESTORE_SIGMASK flag */ clear_thread_flag(TIF_RESTORE_SIGMASK); } return; } /* Did we come from a system call? */ if (current_syscall(regs) >= 0) { /* Restart the system call - no handlers present */ switch (current_syscall_ret(regs)) { case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: regs->ax = regs->orig_ax; regs->ip -= 2; break; case -ERESTART_RESTARTBLOCK: regs->ax = test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall; regs->ip -= 2; break; } } /* * 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); } } void do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags) { #ifdef DEBUG_SIG printk("do_notify_resume flags:%x ip:%lx sp:%lx caller:%p pending:%x\n", thread_info_flags, regs->ip, regs->sp, __builtin_return_address(0),signal_pending(current)); #endif /* Pending single-step? */ if (thread_info_flags & _TIF_SINGLESTEP) { regs->flags |= X86_EFLAGS_TF; clear_thread_flag(TIF_SINGLESTEP); } #ifdef CONFIG_X86_MCE /* notify userspace of pending MCEs */ if (thread_info_flags & _TIF_MCE_NOTIFY) mce_notify_user(); #endif /* CONFIG_X86_MCE */ /* deal with pending signal delivery */ if (thread_info_flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK)) do_signal(regs); if (thread_info_flags & _TIF_HRTICK_RESCHED) hrtick_resched(); } void signal_fault(struct pt_regs *regs, void __user *frame, char *where) { struct task_struct *me = current; if (show_unhandled_signals && printk_ratelimit()) { printk("%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", me->comm,me->pid,where,frame,regs->ip,regs->sp,regs->orig_ax); print_vma_addr(" in ", regs->ip); printk("\n"); } force_sig(SIGSEGV, me); }