/* * 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 #include #include "signal.h" extern const unsigned long sigreturn_codes[17]; static unsigned long signal_return_offset; #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(char __user **auxp) { struct crunch_sigframe __user *frame = (struct crunch_sigframe __user *)*auxp; 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; *auxp += CRUNCH_STORAGE_SIZE; crunch_task_restore(current_thread_info(), &kframe->storage); return 0; } #endif #ifdef CONFIG_IWMMXT static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame) { char kbuf[sizeof(*frame) + 8]; struct iwmmxt_sigframe *kframe; int err = 0; /* the iWMMXt context must be 64 bit aligned */ kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); if (test_thread_flag(TIF_USING_IWMMXT)) { kframe->magic = IWMMXT_MAGIC; kframe->size = IWMMXT_STORAGE_SIZE; iwmmxt_task_copy(current_thread_info(), &kframe->storage); err = __copy_to_user(frame, kframe, sizeof(*frame)); } else { /* * For bug-compatibility with older kernels, some space * has to be reserved for iWMMXt even if it's not used. * Set the magic and size appropriately so that properly * written userspace can skip it reliably: */ __put_user_error(DUMMY_MAGIC, &frame->magic, err); __put_user_error(IWMMXT_STORAGE_SIZE, &frame->size, err); } return err; } static int restore_iwmmxt_context(char __user **auxp) { struct iwmmxt_sigframe __user *frame = (struct iwmmxt_sigframe __user *)*auxp; 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; /* * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy * block is discarded for compatibility with setup_sigframe() if * present, but we don't mandate its presence. If some other * magic is here, it's not for us: */ if (!test_thread_flag(TIF_USING_IWMMXT) && kframe->magic != DUMMY_MAGIC) return 0; if (kframe->size != IWMMXT_STORAGE_SIZE) return -1; if (test_thread_flag(TIF_USING_IWMMXT)) { if (kframe->magic != IWMMXT_MAGIC) return -1; iwmmxt_task_restore(current_thread_info(), &kframe->storage); } *auxp += IWMMXT_STORAGE_SIZE; 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(char __user **auxp) { struct vfp_sigframe __user *frame = (struct vfp_sigframe __user *)*auxp; 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; *auxp += size; 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. */ static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) { char __user *aux; sigset_t set; int err; err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); if (err == 0) 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 = (char __user *) sf->uc.uc_regspace; #ifdef CONFIG_CRUNCH if (err == 0) err |= restore_crunch_context(&aux); #endif #ifdef CONFIG_IWMMXT if (err == 0) err |= restore_iwmmxt_context(&aux); #endif #ifdef CONFIG_VFP if (err == 0) err |= restore_vfp_context(&aux); #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->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->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 (restore_altstack(&frame->sig.uc.uc_stack)) 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) 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 ksignal *ksig, struct pt_regs *regs, int framesize) { unsigned long sp = sigsp(regs->ARM_sp, ksig); void __user *frame; /* * 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 ksignal *ksig, unsigned long __user *rc, void __user *frame) { unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; unsigned long handler_fdpic_GOT = 0; unsigned long retcode; unsigned int idx, thumb = 0; unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) && (current->personality & FDPIC_FUNCPTRS); if (fdpic) { unsigned long __user *fdpic_func_desc = (unsigned long __user *)handler; if (__get_user(handler, &fdpic_func_desc[0]) || __get_user(handler_fdpic_GOT, &fdpic_func_desc[1])) return 1; } cpsr |= PSR_ENDSTATE; /* * Maybe we need to deliver a 32-bit signal to a 26-bit task. */ if (ksig->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; /* * Clear the If-Then Thumb-2 execution state. ARM spec * requires this to be all 000s in ARM mode. Snapdragon * S4/Krait misbehaves on a Thumb=>ARM signal transition * without this. * * We must do this whenever we are running on a Thumb-2 * capable CPU, which includes ARMv6T2. However, we elect * to always do this to simplify the code; this field is * marked UNK/SBZP for older architectures. */ cpsr &= ~PSR_IT_MASK; if (thumb) { cpsr |= PSR_T_BIT; } else cpsr &= ~PSR_T_BIT; } #endif if (ksig->ka.sa.sa_flags & SA_RESTORER) { retcode = (unsigned long)ksig->ka.sa.sa_restorer; if (fdpic) { /* * We need code to load the function descriptor. * That code follows the standard sigreturn code * (6 words), and is made of 3 + 2 words for each * variant. The 4th copied word is the actual FD * address that the assembly code expects. */ idx = 6 + thumb * 3; if (ksig->ka.sa.sa_flags & SA_SIGINFO) idx += 5; if (__put_user(sigreturn_codes[idx], rc ) || __put_user(sigreturn_codes[idx+1], rc+1) || __put_user(sigreturn_codes[idx+2], rc+2) || __put_user(retcode, rc+3)) return 1; goto rc_finish; } } else { idx = thumb << 1; if (ksig->ka.sa.sa_flags & SA_SIGINFO) idx += 3; /* * Put the sigreturn code on the stack no matter which return * mechanism we use in order to remain ABI compliant */ if (__put_user(sigreturn_codes[idx], rc) || __put_user(sigreturn_codes[idx+1], rc+1)) return 1; rc_finish: #ifdef CONFIG_MMU if (cpsr & MODE32_BIT) { struct mm_struct *mm = current->mm; /* * 32-bit code can use the signal return page * except when the MPU has protected the vectors * page from PL0 */ retcode = mm->context.sigpage + signal_return_offset + (idx << 2) + thumb; } else #endif { /* * Ensure that the instruction cache sees * the return code written onto the stack. */ flush_icache_range((unsigned long)rc, (unsigned long)(rc + 3)); retcode = ((unsigned long)rc) + thumb; } } regs->ARM_r0 = ksig->sig; regs->ARM_sp = (unsigned long)frame; regs->ARM_lr = retcode; regs->ARM_pc = handler; if (fdpic) regs->ARM_r9 = handler_fdpic_GOT; regs->ARM_cpsr = cpsr; return 0; } static int setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct sigframe __user *frame = get_sigframe(ksig, 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, ksig, frame->retcode, frame); return err; } static int setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); int err = 0; if (!frame) return 1; err |= copy_siginfo_to_user(&frame->info, &ksig->info); __put_user_error(0, &frame->sig.uc.uc_flags, err); __put_user_error(NULL, &frame->sig.uc.uc_link, err); err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); err |= setup_sigframe(&frame->sig, regs, set); if (err == 0) err = setup_return(regs, ksig, frame->sig.retcode, frame); 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 void handle_signal(struct ksignal *ksig, struct pt_regs *regs) { sigset_t *oldset = sigmask_to_save(); int ret; /* * Increment event counter and perform fixup for the pre-signal * frame. */ rseq_signal_deliver(regs); /* * Set up the stack frame */ if (ksig->ka.sa.sa_flags & SA_SIGINFO) ret = setup_rt_frame(ksig, oldset, regs); else ret = setup_frame(ksig, oldset, regs); /* * Check that the resulting registers are actually sane. */ ret |= !valid_user_regs(regs); signal_setup_done(ret, ksig, 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 int do_signal(struct pt_regs *regs, int syscall) { unsigned int retval = 0, continue_addr = 0, restart_addr = 0; struct ksignal ksig; int restart = 0; /* * 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 -ERESTART_RESTARTBLOCK: restart -= 2; case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: restart++; regs->ARM_r0 = regs->ARM_ORIG_r0; regs->ARM_pc = restart_addr; break; } } /* * Get the signal to deliver. When running under ptrace, at this * point the debugger may change all our registers ... */ /* * 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 (get_signal(&ksig)) { /* handler */ if (unlikely(restart) && regs->ARM_pc == restart_addr) { if (retval == -ERESTARTNOHAND || retval == -ERESTART_RESTARTBLOCK || (retval == -ERESTARTSYS && !(ksig.ka.sa.sa_flags & SA_RESTART))) { regs->ARM_r0 = -EINTR; regs->ARM_pc = continue_addr; } } handle_signal(&ksig, regs); } else { /* no handler */ restore_saved_sigmask(); if (unlikely(restart) && regs->ARM_pc == restart_addr) { regs->ARM_pc = continue_addr; return restart; } } return 0; } asmlinkage int do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) { /* * The assembly code enters us with IRQs off, but it hasn't * informed the tracing code of that for efficiency reasons. * Update the trace code with the current status. */ trace_hardirqs_off(); do { if (likely(thread_flags & _TIF_NEED_RESCHED)) { schedule(); } else { if (unlikely(!user_mode(regs))) return 0; local_irq_enable(); if (thread_flags & _TIF_SIGPENDING) { int restart = do_signal(regs, syscall); if (unlikely(restart)) { /* * Restart without handlers. * Deal with it without leaving * the kernel space. */ return restart; } syscall = 0; } else if (thread_flags & _TIF_UPROBE) { uprobe_notify_resume(regs); } else { clear_thread_flag(TIF_NOTIFY_RESUME); tracehook_notify_resume(regs); rseq_handle_notify_resume(regs); } } local_irq_disable(); thread_flags = current_thread_info()->flags; } while (thread_flags & _TIF_WORK_MASK); return 0; } struct page *get_signal_page(void) { unsigned long ptr; unsigned offset; struct page *page; void *addr; page = alloc_pages(GFP_KERNEL, 0); if (!page) return NULL; addr = page_address(page); /* Give the signal return code some randomness */ offset = 0x200 + (get_random_int() & 0x7fc); signal_return_offset = offset; /* * Copy signal return handlers into the vector page, and * set sigreturn to be a pointer to these. */ memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); ptr = (unsigned long)addr + offset; flush_icache_range(ptr, ptr + sizeof(sigreturn_codes)); return page; } /* Defer to generic check */ asmlinkage void addr_limit_check_failed(void) { addr_limit_user_check(); } #ifdef CONFIG_DEBUG_RSEQ asmlinkage void do_rseq_syscall(struct pt_regs *regs) { rseq_syscall(regs); } #endif