/* * 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 */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/sched.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/kernel.h> #include <linux/errno.h> #include <linux/wait.h> #include <linux/tracehook.h> #include <linux/unistd.h> #include <linux/stddef.h> #include <linux/personality.h> #include <linux/uaccess.h> #include <linux/user-return-notifier.h> #include <linux/uprobes.h> #include <linux/context_tracking.h> #include <asm/processor.h> #include <asm/ucontext.h> #include <asm/i387.h> #include <asm/fpu-internal.h> #include <asm/vdso.h> #include <asm/mce.h> #include <asm/sighandling.h> #ifdef CONFIG_X86_64 #include <asm/proto.h> #include <asm/ia32_unistd.h> #include <asm/sys_ia32.h> #endif /* CONFIG_X86_64 */ #include <asm/syscall.h> #include <asm/syscalls.h> #include <asm/sigframe.h> #ifdef CONFIG_X86_32 # define FIX_EFLAGS (__FIX_EFLAGS | X86_EFLAGS_RF) #else # define FIX_EFLAGS __FIX_EFLAGS #endif #define COPY(x) do { \ get_user_ex(regs->x, &sc->x); \ } while (0) #define GET_SEG(seg) ({ \ unsigned short tmp; \ get_user_ex(tmp, &sc->seg); \ tmp; \ }) #define COPY_SEG(seg) do { \ regs->seg = GET_SEG(seg); \ } while (0) #define COPY_SEG_CPL3(seg) do { \ regs->seg = GET_SEG(seg) | 3; \ } while (0) int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *pax) { void __user *buf; unsigned int tmpflags; unsigned int err = 0; /* Always make any pending restarted system calls return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; get_user_try { #ifdef CONFIG_X86_32 set_user_gs(regs, GET_SEG(gs)); COPY_SEG(fs); COPY_SEG(es); COPY_SEG(ds); #endif /* CONFIG_X86_32 */ COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx); COPY(dx); COPY(cx); COPY(ip); #ifdef CONFIG_X86_64 COPY(r8); COPY(r9); COPY(r10); COPY(r11); COPY(r12); COPY(r13); COPY(r14); COPY(r15); #endif /* CONFIG_X86_64 */ #ifdef CONFIG_X86_32 COPY_SEG_CPL3(cs); COPY_SEG_CPL3(ss); #else /* !CONFIG_X86_32 */ /* 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. */ COPY_SEG_CPL3(cs); #endif /* CONFIG_X86_32 */ get_user_ex(tmpflags, &sc->flags); regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS); regs->orig_ax = -1; /* disable syscall checks */ get_user_ex(buf, &sc->fpstate); get_user_ex(*pax, &sc->ax); } get_user_catch(err); err |= restore_xstate_sig(buf, config_enabled(CONFIG_X86_32)); return err; } int setup_sigcontext(struct sigcontext __user *sc, void __user *fpstate, struct pt_regs *regs, unsigned long mask) { int err = 0; put_user_try { #ifdef CONFIG_X86_32 put_user_ex(get_user_gs(regs), (unsigned int __user *)&sc->gs); put_user_ex(regs->fs, (unsigned int __user *)&sc->fs); put_user_ex(regs->es, (unsigned int __user *)&sc->es); put_user_ex(regs->ds, (unsigned int __user *)&sc->ds); #endif /* CONFIG_X86_32 */ put_user_ex(regs->di, &sc->di); put_user_ex(regs->si, &sc->si); put_user_ex(regs->bp, &sc->bp); put_user_ex(regs->sp, &sc->sp); put_user_ex(regs->bx, &sc->bx); put_user_ex(regs->dx, &sc->dx); put_user_ex(regs->cx, &sc->cx); put_user_ex(regs->ax, &sc->ax); #ifdef CONFIG_X86_64 put_user_ex(regs->r8, &sc->r8); put_user_ex(regs->r9, &sc->r9); put_user_ex(regs->r10, &sc->r10); put_user_ex(regs->r11, &sc->r11); put_user_ex(regs->r12, &sc->r12); put_user_ex(regs->r13, &sc->r13); put_user_ex(regs->r14, &sc->r14); put_user_ex(regs->r15, &sc->r15); #endif /* CONFIG_X86_64 */ put_user_ex(current->thread.trap_nr, &sc->trapno); put_user_ex(current->thread.error_code, &sc->err); put_user_ex(regs->ip, &sc->ip); #ifdef CONFIG_X86_32 put_user_ex(regs->cs, (unsigned int __user *)&sc->cs); put_user_ex(regs->flags, &sc->flags); put_user_ex(regs->sp, &sc->sp_at_signal); put_user_ex(regs->ss, (unsigned int __user *)&sc->ss); #else /* !CONFIG_X86_32 */ put_user_ex(regs->flags, &sc->flags); put_user_ex(regs->cs, &sc->cs); put_user_ex(0, &sc->gs); put_user_ex(0, &sc->fs); #endif /* CONFIG_X86_32 */ put_user_ex(fpstate, &sc->fpstate); /* non-iBCS2 extensions.. */ put_user_ex(mask, &sc->oldmask); put_user_ex(current->thread.cr2, &sc->cr2); } put_user_catch(err); return err; } /* * Set up a signal frame. */ /* * Determine which stack to use.. */ static unsigned long align_sigframe(unsigned long sp) { #ifdef CONFIG_X86_32 /* * 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; #else /* !CONFIG_X86_32 */ sp = round_down(sp, 16) - 8; #endif return sp; } static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size, void __user **fpstate) { /* Default to using normal stack */ unsigned long math_size = 0; unsigned long sp = regs->sp; unsigned long buf_fx = 0; int onsigstack = on_sig_stack(sp); /* redzone */ if (config_enabled(CONFIG_X86_64)) sp -= 128; if (!onsigstack) { /* This is the X/Open sanctioned signal stack switching. */ if (ka->sa.sa_flags & SA_ONSTACK) { if (current->sas_ss_size) sp = current->sas_ss_sp + current->sas_ss_size; } else if (config_enabled(CONFIG_X86_32) && (regs->ss & 0xffff) != __USER_DS && !(ka->sa.sa_flags & SA_RESTORER) && ka->sa.sa_restorer) { /* This is the legacy signal stack switching. */ sp = (unsigned long) ka->sa.sa_restorer; } } if (used_math()) { sp = alloc_mathframe(sp, config_enabled(CONFIG_X86_32), &buf_fx, &math_size); *fpstate = (void __user *)sp; } sp = align_sigframe(sp - frame_size); /* * 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 (onsigstack && !likely(on_sig_stack(sp))) return (void __user *)-1L; /* save i387 and extended state */ if (used_math() && save_xstate_sig(*fpstate, (void __user *)buf_fx, math_size) < 0) return (void __user *)-1L; return (void __user *)sp; } #ifdef CONFIG_X86_32 static const struct { u16 poplmovl; u32 val; u16 int80; } __attribute__((packed)) retcode = { 0xb858, /* popl %eax; movl $..., %eax */ __NR_sigreturn, 0x80cd, /* int $0x80 */ }; static const struct { u8 movl; u32 val; u16 int80; u8 pad; } __attribute__((packed)) rt_retcode = { 0xb8, /* movl $..., %eax */ __NR_rt_sigreturn, 0x80cd, /* int $0x80 */ 0 }; static int __setup_frame(int sig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct sigframe __user *frame; void __user *restorer; int err = 0; void __user *fpstate = NULL; frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) return -EFAULT; if (__put_user(sig, &frame->sig)) return -EFAULT; if (setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0])) return -EFAULT; if (_NSIG_WORDS > 1) { if (__copy_to_user(&frame->extramask, &set->sig[1], sizeof(frame->extramask))) return -EFAULT; } if (current->mm->context.vdso) restorer = VDSO32_SYMBOL(current->mm->context.vdso, sigreturn); else restorer = &frame->retcode; if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->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(*((u64 *)&retcode), (u64 *)frame->retcode); if (err) return -EFAULT; /* Set up registers for signal handler */ regs->sp = (unsigned long)frame; regs->ip = (unsigned long)ksig->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; } static int __setup_rt_frame(int sig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe __user *frame; void __user *restorer; int err = 0; void __user *fpstate = NULL; frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) return -EFAULT; put_user_try { put_user_ex(sig, &frame->sig); put_user_ex(&frame->info, &frame->pinfo); put_user_ex(&frame->uc, &frame->puc); /* Create the ucontext. */ if (cpu_has_xsave) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); err |= __save_altstack(&frame->uc.uc_stack, regs->sp); /* Set up to return from userspace. */ restorer = VDSO32_SYMBOL(current->mm->context.vdso, rt_sigreturn); if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = ksig->ka.sa.sa_restorer; put_user_ex(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. */ put_user_ex(*((u64 *)&rt_retcode), (u64 *)frame->retcode); } put_user_catch(err); err |= copy_siginfo_to_user(&frame->info, &ksig->info); err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, regs, set->sig[0]); err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); if (err) return -EFAULT; /* Set up registers for signal handler */ regs->sp = (unsigned long)frame; regs->ip = (unsigned long)ksig->ka.sa.sa_handler; regs->ax = (unsigned long)sig; 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; } #else /* !CONFIG_X86_32 */ static int __setup_rt_frame(int sig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe __user *frame; void __user *fp = NULL; int err = 0; frame = get_sigframe(&ksig->ka, regs, sizeof(struct rt_sigframe), &fp); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) return -EFAULT; if (ksig->ka.sa.sa_flags & SA_SIGINFO) { if (copy_siginfo_to_user(&frame->info, &ksig->info)) return -EFAULT; } put_user_try { /* Create the ucontext. */ if (cpu_has_xsave) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); err |= __save_altstack(&frame->uc.uc_stack, regs->sp); /* Set up to return from userspace. If provided, use a stub already in userspace. */ /* x86-64 should always use SA_RESTORER. */ if (ksig->ka.sa.sa_flags & SA_RESTORER) { put_user_ex(ksig->ka.sa.sa_restorer, &frame->pretcode); } else { /* could use a vstub here */ err |= -EFAULT; } } put_user_catch(err); err |= setup_sigcontext(&frame->uc.uc_mcontext, fp, regs, set->sig[0]); err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); if (err) return -EFAULT; /* 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) ksig->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; return 0; } #endif /* CONFIG_X86_32 */ static int x32_setup_rt_frame(struct ksignal *ksig, compat_sigset_t *set, struct pt_regs *regs) { #ifdef CONFIG_X86_X32_ABI struct rt_sigframe_x32 __user *frame; void __user *restorer; int err = 0; void __user *fpstate = NULL; frame = get_sigframe(&ksig->ka, regs, sizeof(*frame), &fpstate); if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) return -EFAULT; if (ksig->ka.sa.sa_flags & SA_SIGINFO) { if (copy_siginfo_to_user32(&frame->info, &ksig->info)) return -EFAULT; } put_user_try { /* Create the ucontext. */ if (cpu_has_xsave) put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags); else put_user_ex(0, &frame->uc.uc_flags); put_user_ex(0, &frame->uc.uc_link); err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp); put_user_ex(0, &frame->uc.uc__pad0); if (ksig->ka.sa.sa_flags & SA_RESTORER) { restorer = ksig->ka.sa.sa_restorer; } else { /* could use a vstub here */ restorer = NULL; err |= -EFAULT; } put_user_ex(restorer, &frame->pretcode); } put_user_catch(err); err |= setup_sigcontext(&frame->uc.uc_mcontext, fpstate, regs, set->sig[0]); err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); if (err) return -EFAULT; /* Set up registers for signal handler */ regs->sp = (unsigned long) frame; regs->ip = (unsigned long) ksig->ka.sa.sa_handler; /* We use the x32 calling convention here... */ regs->di = ksig->sig; regs->si = (unsigned long) &frame->info; regs->dx = (unsigned long) &frame->uc; loadsegment(ds, __USER_DS); loadsegment(es, __USER_DS); regs->cs = __USER_CS; regs->ss = __USER_DS; #endif /* CONFIG_X86_X32_ABI */ return 0; } /* * Do a signal return; undo the signal stack. */ #ifdef CONFIG_X86_32 unsigned long sys_sigreturn(void) { struct pt_regs *regs = current_pt_regs(); struct sigframe __user *frame; unsigned long ax; sigset_t set; 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; set_current_blocked(&set); if (restore_sigcontext(regs, &frame->sc, &ax)) goto badframe; return ax; badframe: signal_fault(regs, frame, "sigreturn"); return 0; } #endif /* CONFIG_X86_32 */ long sys_rt_sigreturn(void) { struct pt_regs *regs = current_pt_regs(); 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; set_current_blocked(&set); if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax)) goto badframe; if (restore_altstack(&frame->uc.uc_stack)) goto badframe; return ax; badframe: signal_fault(regs, frame, "rt_sigreturn"); return 0; } /* * OK, we're invoking a handler: */ static int signr_convert(int sig) { #ifdef CONFIG_X86_32 struct thread_info *info = current_thread_info(); if (info->exec_domain && info->exec_domain->signal_invmap && sig < 32) return info->exec_domain->signal_invmap[sig]; #endif /* CONFIG_X86_32 */ return sig; } static int setup_rt_frame(struct ksignal *ksig, struct pt_regs *regs) { int usig = signr_convert(ksig->sig); sigset_t *set = sigmask_to_save(); compat_sigset_t *cset = (compat_sigset_t *) set; /* Set up the stack frame */ if (is_ia32_frame()) { if (ksig->ka.sa.sa_flags & SA_SIGINFO) return ia32_setup_rt_frame(usig, ksig, cset, regs); else return ia32_setup_frame(usig, ksig, cset, regs); } else if (is_x32_frame()) { return x32_setup_rt_frame(ksig, cset, regs); } else { return __setup_rt_frame(ksig->sig, ksig, set, regs); } } static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) { bool failed; /* Are we from a system call? */ if (syscall_get_nr(current, regs) >= 0) { /* If so, check system call restarting.. */ switch (syscall_get_error(current, regs)) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: regs->ax = -EINTR; break; case -ERESTARTSYS: if (!(ksig->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; failed = (setup_rt_frame(ksig, regs) < 0); if (!failed) { /* * 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; } signal_setup_done(failed, ksig, test_thread_flag(TIF_SINGLESTEP)); } #ifdef CONFIG_X86_32 #define NR_restart_syscall __NR_restart_syscall #else /* !CONFIG_X86_32 */ #define NR_restart_syscall \ test_thread_flag(TIF_IA32) ? __NR_ia32_restart_syscall : __NR_restart_syscall #endif /* CONFIG_X86_32 */ /* * 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 ksignal ksig; if (get_signal(&ksig)) { /* Whee! Actually deliver the signal. */ handle_signal(&ksig, regs); return; } /* Did we come from a system call? */ if (syscall_get_nr(current, regs) >= 0) { /* Restart the system call - no handlers present */ switch (syscall_get_error(current, regs)) { 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. */ restore_saved_sigmask(); } /* * 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) { user_exit(); #ifdef CONFIG_X86_MCE /* notify userspace of pending MCEs */ if (thread_info_flags & _TIF_MCE_NOTIFY) mce_notify_process(); #endif /* CONFIG_X86_64 && CONFIG_X86_MCE */ if (thread_info_flags & _TIF_UPROBE) uprobe_notify_resume(regs); /* deal with pending signal delivery */ if (thread_info_flags & _TIF_SIGPENDING) do_signal(regs); if (thread_info_flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); } if (thread_info_flags & _TIF_USER_RETURN_NOTIFY) fire_user_return_notifiers(); user_enter(); } 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" "%s[%d] bad frame in %s frame:%p ip:%lx sp:%lx orax:%lx", task_pid_nr(current) > 1 ? KERN_INFO : KERN_EMERG, me->comm, me->pid, where, frame, regs->ip, regs->sp, regs->orig_ax); print_vma_addr(" in ", regs->ip); pr_cont("\n"); } force_sig(SIGSEGV, me); } #ifdef CONFIG_X86_X32_ABI asmlinkage long sys32_x32_rt_sigreturn(void) { struct pt_regs *regs = current_pt_regs(); struct rt_sigframe_x32 __user *frame; sigset_t set; unsigned long ax; frame = (struct rt_sigframe_x32 __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; set_current_blocked(&set); if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &ax)) goto badframe; if (compat_restore_altstack(&frame->uc.uc_stack)) goto badframe; return ax; badframe: signal_fault(regs, frame, "x32 rt_sigreturn"); return 0; } #endif