/* * linux/arch/arm/kernel/signal.c * * Copyright (C) 1995-2009 Russell King * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #include #include #include #include #include "signal.h" #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) /* * For ARM syscalls, we encode the syscall number into the instruction. */ #define SWI_SYS_SIGRETURN (0xef000000|(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE)) #define SWI_SYS_RT_SIGRETURN (0xef000000|(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE)) #define SWI_SYS_RESTART (0xef000000|__NR_restart_syscall|__NR_OABI_SYSCALL_BASE) /* * With EABI, the syscall number has to be loaded into r7. */ #define MOV_R7_NR_SIGRETURN (0xe3a07000 | (__NR_sigreturn - __NR_SYSCALL_BASE)) #define MOV_R7_NR_RT_SIGRETURN (0xe3a07000 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) /* * For Thumb syscalls, we pass the syscall number via r7. We therefore * need two 16-bit instructions. */ #define SWI_THUMB_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_sigreturn - __NR_SYSCALL_BASE)) #define SWI_THUMB_RT_SIGRETURN (0xdf00 << 16 | 0x2700 | (__NR_rt_sigreturn - __NR_SYSCALL_BASE)) const unsigned long sigreturn_codes[7] = { MOV_R7_NR_SIGRETURN, SWI_SYS_SIGRETURN, SWI_THUMB_SIGRETURN, MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN, }; /* * Either we support OABI only, or we have EABI with the OABI * compat layer enabled. In the later case we don't know if * user space is EABI or not, and if not we must not clobber r7. * Always using the OABI syscall solves that issue and works for * all those cases. */ const unsigned long syscall_restart_code[2] = { SWI_SYS_RESTART, /* swi __NR_restart_syscall */ 0xe49df004, /* ldr pc, [sp], #4 */ }; /* * atomically swap in the new signal mask, and wait for a signal. */ asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask) { sigset_t blocked; current->saved_sigmask = current->blocked; mask &= _BLOCKABLE; siginitset(&blocked, mask); set_current_blocked(&blocked); 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; } #ifdef CONFIG_CRUNCH static int preserve_crunch_context(struct crunch_sigframe __user *frame) { char kbuf[sizeof(*frame) + 8]; struct crunch_sigframe *kframe; /* the crunch context must be 64 bit aligned */ kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); kframe->magic = CRUNCH_MAGIC; kframe->size = CRUNCH_STORAGE_SIZE; crunch_task_copy(current_thread_info(), &kframe->storage); return __copy_to_user(frame, kframe, sizeof(*frame)); } static int restore_crunch_context(struct crunch_sigframe __user *frame) { char kbuf[sizeof(*frame) + 8]; struct crunch_sigframe *kframe; /* the crunch context must be 64 bit aligned */ kframe = (struct crunch_sigframe *)((unsigned long)(kbuf + 8) & ~7); if (__copy_from_user(kframe, frame, sizeof(*frame))) return -1; if (kframe->magic != CRUNCH_MAGIC || kframe->size != CRUNCH_STORAGE_SIZE) return -1; crunch_task_restore(current_thread_info(), &kframe->storage); return 0; } #endif #ifdef CONFIG_IWMMXT static int preserve_iwmmxt_context(struct iwmmxt_sigframe *frame) { char kbuf[sizeof(*frame) + 8]; struct iwmmxt_sigframe *kframe; /* the iWMMXt context must be 64 bit aligned */ kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); kframe->magic = IWMMXT_MAGIC; kframe->size = IWMMXT_STORAGE_SIZE; iwmmxt_task_copy(current_thread_info(), &kframe->storage); return __copy_to_user(frame, kframe, sizeof(*frame)); } static int restore_iwmmxt_context(struct iwmmxt_sigframe *frame) { char kbuf[sizeof(*frame) + 8]; struct iwmmxt_sigframe *kframe; /* the iWMMXt context must be 64 bit aligned */ kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); if (__copy_from_user(kframe, frame, sizeof(*frame))) return -1; if (kframe->magic != IWMMXT_MAGIC || kframe->size != IWMMXT_STORAGE_SIZE) return -1; iwmmxt_task_restore(current_thread_info(), &kframe->storage); return 0; } #endif #ifdef CONFIG_VFP static int preserve_vfp_context(struct vfp_sigframe __user *frame) { const unsigned long magic = VFP_MAGIC; const unsigned long size = VFP_STORAGE_SIZE; int err = 0; __put_user_error(magic, &frame->magic, err); __put_user_error(size, &frame->size, err); if (err) return -EFAULT; return vfp_preserve_user_clear_hwstate(&frame->ufp, &frame->ufp_exc); } static int restore_vfp_context(struct vfp_sigframe __user *frame) { unsigned long magic; unsigned long size; int err = 0; __get_user_error(magic, &frame->magic, err); __get_user_error(size, &frame->size, err); if (err) return -EFAULT; if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) return -EINVAL; return vfp_restore_user_hwstate(&frame->ufp, &frame->ufp_exc); } #endif /* * Do a signal return; undo the signal stack. These are aligned to 64-bit. */ struct sigframe { struct ucontext uc; unsigned long retcode[2]; }; struct rt_sigframe { struct siginfo info; struct sigframe sig; }; static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) { struct aux_sigframe __user *aux; sigset_t set; int err; err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); if (err == 0) { sigdelsetmask(&set, ~_BLOCKABLE); set_current_blocked(&set); } __get_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); __get_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); __get_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); __get_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); __get_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); __get_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); __get_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); __get_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); __get_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); __get_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); __get_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); __get_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); __get_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); __get_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); __get_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); __get_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); __get_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); err |= !valid_user_regs(regs); aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; #ifdef CONFIG_CRUNCH if (err == 0) err |= restore_crunch_context(&aux->crunch); #endif #ifdef CONFIG_IWMMXT if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) err |= restore_iwmmxt_context(&aux->iwmmxt); #endif #ifdef CONFIG_VFP if (err == 0) err |= restore_vfp_context(&aux->vfp); #endif return err; } asmlinkage int sys_sigreturn(struct pt_regs *regs) { struct sigframe __user *frame; /* Always make any pending restarted system calls return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; /* * Since we stacked the signal on a 64-bit boundary, * then 'sp' should be word aligned here. If it's * not, then the user is trying to mess with us. */ if (regs->ARM_sp & 7) goto badframe; frame = (struct sigframe __user *)regs->ARM_sp; if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) goto badframe; if (restore_sigframe(regs, frame)) goto badframe; return regs->ARM_r0; badframe: force_sig(SIGSEGV, current); return 0; } asmlinkage int sys_rt_sigreturn(struct pt_regs *regs) { struct rt_sigframe __user *frame; /* Always make any pending restarted system calls return -EINTR */ current_thread_info()->restart_block.fn = do_no_restart_syscall; /* * Since we stacked the signal on a 64-bit boundary, * then 'sp' should be word aligned here. If it's * not, then the user is trying to mess with us. */ if (regs->ARM_sp & 7) goto badframe; frame = (struct rt_sigframe __user *)regs->ARM_sp; if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) goto badframe; if (restore_sigframe(regs, &frame->sig)) goto badframe; if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->ARM_sp) == -EFAULT) goto badframe; return regs->ARM_r0; badframe: force_sig(SIGSEGV, current); return 0; } static int setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) { struct aux_sigframe __user *aux; int err = 0; __put_user_error(regs->ARM_r0, &sf->uc.uc_mcontext.arm_r0, err); __put_user_error(regs->ARM_r1, &sf->uc.uc_mcontext.arm_r1, err); __put_user_error(regs->ARM_r2, &sf->uc.uc_mcontext.arm_r2, err); __put_user_error(regs->ARM_r3, &sf->uc.uc_mcontext.arm_r3, err); __put_user_error(regs->ARM_r4, &sf->uc.uc_mcontext.arm_r4, err); __put_user_error(regs->ARM_r5, &sf->uc.uc_mcontext.arm_r5, err); __put_user_error(regs->ARM_r6, &sf->uc.uc_mcontext.arm_r6, err); __put_user_error(regs->ARM_r7, &sf->uc.uc_mcontext.arm_r7, err); __put_user_error(regs->ARM_r8, &sf->uc.uc_mcontext.arm_r8, err); __put_user_error(regs->ARM_r9, &sf->uc.uc_mcontext.arm_r9, err); __put_user_error(regs->ARM_r10, &sf->uc.uc_mcontext.arm_r10, err); __put_user_error(regs->ARM_fp, &sf->uc.uc_mcontext.arm_fp, err); __put_user_error(regs->ARM_ip, &sf->uc.uc_mcontext.arm_ip, err); __put_user_error(regs->ARM_sp, &sf->uc.uc_mcontext.arm_sp, err); __put_user_error(regs->ARM_lr, &sf->uc.uc_mcontext.arm_lr, err); __put_user_error(regs->ARM_pc, &sf->uc.uc_mcontext.arm_pc, err); __put_user_error(regs->ARM_cpsr, &sf->uc.uc_mcontext.arm_cpsr, err); __put_user_error(current->thread.trap_no, &sf->uc.uc_mcontext.trap_no, err); __put_user_error(current->thread.error_code, &sf->uc.uc_mcontext.error_code, err); __put_user_error(current->thread.address, &sf->uc.uc_mcontext.fault_address, err); __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err); err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; #ifdef CONFIG_CRUNCH if (err == 0) err |= preserve_crunch_context(&aux->crunch); #endif #ifdef CONFIG_IWMMXT if (err == 0 && test_thread_flag(TIF_USING_IWMMXT)) err |= preserve_iwmmxt_context(&aux->iwmmxt); #endif #ifdef CONFIG_VFP if (err == 0) err |= preserve_vfp_context(&aux->vfp); #endif __put_user_error(0, &aux->end_magic, err); return err; } static inline void __user * get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, int framesize) { unsigned long sp = regs->ARM_sp; void __user *frame; /* * This is the X/Open sanctioned signal stack switching. */ if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp)) sp = current->sas_ss_sp + current->sas_ss_size; /* * ATPCS B01 mandates 8-byte alignment */ frame = (void __user *)((sp - framesize) & ~7); /* * Check that we can actually write to the signal frame. */ if (!access_ok(VERIFY_WRITE, frame, framesize)) frame = NULL; return frame; } static int setup_return(struct pt_regs *regs, struct k_sigaction *ka, unsigned long __user *rc, void __user *frame, int usig) { unsigned long handler = (unsigned long)ka->sa.sa_handler; unsigned long retcode; int thumb = 0; unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); cpsr |= PSR_ENDSTATE; /* * Maybe we need to deliver a 32-bit signal to a 26-bit task. */ if (ka->sa.sa_flags & SA_THIRTYTWO) cpsr = (cpsr & ~MODE_MASK) | USR_MODE; #ifdef CONFIG_ARM_THUMB if (elf_hwcap & HWCAP_THUMB) { /* * The LSB of the handler determines if we're going to * be using THUMB or ARM mode for this signal handler. */ thumb = handler & 1; if (thumb) { cpsr |= PSR_T_BIT; #if __LINUX_ARM_ARCH__ >= 7 /* clear the If-Then Thumb-2 execution state */ cpsr &= ~PSR_IT_MASK; #endif } else cpsr &= ~PSR_T_BIT; } #endif if (ka->sa.sa_flags & SA_RESTORER) { retcode = (unsigned long)ka->sa.sa_restorer; } else { unsigned int idx = thumb << 1; if (ka->sa.sa_flags & SA_SIGINFO) idx += 3; if (__put_user(sigreturn_codes[idx], rc) || __put_user(sigreturn_codes[idx+1], rc+1)) return 1; if (cpsr & MODE32_BIT) { /* * 32-bit code can use the new high-page * signal return code support. */ retcode = KERN_SIGRETURN_CODE + (idx << 2) + thumb; } else { /* * Ensure that the instruction cache sees * the return code written onto the stack. */ flush_icache_range((unsigned long)rc, (unsigned long)(rc + 2)); retcode = ((unsigned long)rc) + thumb; } } regs->ARM_r0 = usig; regs->ARM_sp = (unsigned long)frame; regs->ARM_lr = retcode; regs->ARM_pc = handler; regs->ARM_cpsr = cpsr; return 0; } static int setup_frame(int usig, struct k_sigaction *ka, sigset_t *set, struct pt_regs *regs) { struct sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame)); int err = 0; if (!frame) return 1; /* * Set uc.uc_flags to a value which sc.trap_no would never have. */ __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); err |= setup_sigframe(frame, regs, set); if (err == 0) err = setup_return(regs, ka, frame->retcode, frame, usig); return err; } static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe __user *frame = get_sigframe(ka, regs, sizeof(*frame)); stack_t stack; int err = 0; if (!frame) return 1; err |= copy_siginfo_to_user(&frame->info, info); __put_user_error(0, &frame->sig.uc.uc_flags, err); __put_user_error(NULL, &frame->sig.uc.uc_link, err); memset(&stack, 0, sizeof(stack)); stack.ss_sp = (void __user *)current->sas_ss_sp; stack.ss_flags = sas_ss_flags(regs->ARM_sp); stack.ss_size = current->sas_ss_size; err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack)); err |= setup_sigframe(&frame->sig, regs, set); if (err == 0) err = setup_return(regs, ka, frame->sig.retcode, frame, usig); if (err == 0) { /* * For realtime signals we must also set the second and third * arguments for the signal handler. * -- Peter Maydell 2000-12-06 */ regs->ARM_r1 = (unsigned long)&frame->info; regs->ARM_r2 = (unsigned long)&frame->sig.uc; } return err; } /* * OK, we're invoking a handler */ static int handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info, sigset_t *oldset, struct pt_regs * regs) { struct thread_info *thread = current_thread_info(); struct task_struct *tsk = current; int usig = sig; int ret; /* * translate the signal */ if (usig < 32 && thread->exec_domain && thread->exec_domain->signal_invmap) usig = thread->exec_domain->signal_invmap[usig]; /* * Set up the stack frame */ if (ka->sa.sa_flags & SA_SIGINFO) ret = setup_rt_frame(usig, ka, info, oldset, regs); else ret = setup_frame(usig, ka, oldset, regs); /* * Check that the resulting registers are actually sane. */ ret |= !valid_user_regs(regs); if (ret != 0) { force_sigsegv(sig, tsk); return ret; } /* * Block the signal if we were successful. */ block_sigmask(ka, sig); 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. * * Note that we go through the signals twice: once to check the signals that * the kernel can handle, and then we build all the user-level signal handling * stack-frames in one go after that. */ static void do_signal(struct pt_regs *regs, int syscall) { unsigned int retval = 0, continue_addr = 0, restart_addr = 0; struct k_sigaction ka; siginfo_t info; int signr; /* * 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 (!user_mode(regs)) return; /* * If we were from a system call, check for system call restarting... */ if (syscall) { continue_addr = regs->ARM_pc; restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4); retval = regs->ARM_r0; /* * Prepare for system call restart. We do this here so that a * debugger will see the already changed PSW. */ switch (retval) { case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: regs->ARM_r0 = regs->ARM_ORIG_r0; regs->ARM_pc = restart_addr; break; case -ERESTART_RESTARTBLOCK: regs->ARM_r0 = -EINTR; break; } } if (try_to_freeze_nowarn()) goto no_signal; /* * Get the signal to deliver. When running under ptrace, at this * point the debugger may change all our registers ... */ signr = get_signal_to_deliver(&info, &ka, regs, NULL); if (signr > 0) { sigset_t *oldset; /* * Depending on the signal settings we may need to revert the * decision to restart the system call. But skip this if a * debugger has chosen to restart at a different PC. */ if (regs->ARM_pc == restart_addr) { if (retval == -ERESTARTNOHAND || (retval == -ERESTARTSYS && !(ka.sa.sa_flags & SA_RESTART))) { regs->ARM_r0 = -EINTR; regs->ARM_pc = continue_addr; } } if (test_thread_flag(TIF_RESTORE_SIGMASK)) oldset = ¤t->saved_sigmask; else oldset = ¤t->blocked; if (handle_signal(signr, &ka, &info, 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. */ if (test_thread_flag(TIF_RESTORE_SIGMASK)) clear_thread_flag(TIF_RESTORE_SIGMASK); } return; } no_signal: if (syscall) { /* * Handle restarting a different system call. As above, * if a debugger has chosen to restart at a different PC, * ignore the restart. */ if (retval == -ERESTART_RESTARTBLOCK && regs->ARM_pc == continue_addr) { if (thumb_mode(regs)) { regs->ARM_r7 = __NR_restart_syscall - __NR_SYSCALL_BASE; regs->ARM_pc -= 2; } else { #if defined(CONFIG_AEABI) && !defined(CONFIG_OABI_COMPAT) regs->ARM_r7 = __NR_restart_syscall; regs->ARM_pc -= 4; #else u32 __user *usp; regs->ARM_sp -= 4; usp = (u32 __user *)regs->ARM_sp; if (put_user(regs->ARM_pc, usp) == 0) { regs->ARM_pc = KERN_RESTART_CODE; } else { regs->ARM_sp += 4; force_sigsegv(0, current); } #endif } } /* 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); } } } asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall) { if (thread_flags & _TIF_SIGPENDING) do_signal(regs, syscall); if (thread_flags & _TIF_NOTIFY_RESUME) { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); if (current->replacement_session_keyring) key_replace_session_keyring(); } }