/**************************************************************************** * arch/arm/src/armv7-a/arm_schedulesigaction.c * * Copyright (C) 2013 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include "arm.h" #include "sched/sched.h" #include "up_internal.h" #include "up_arch.h" #ifndef CONFIG_DISABLE_SIGNALS /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: up_schedule_sigaction * * Description: * This function is called by the OS when one or more * signal handling actions have been queued for execution. * The architecture specific code must configure things so * that the 'sigdeliver' callback is executed on the thread * specified by 'tcb' as soon as possible. * * This function may be called from interrupt handling logic. * * This operation should not cause the task to be unblocked * nor should it cause any immediate execution of sigdeliver. * Typically, a few cases need to be considered: * * (1) This function may be called from an interrupt handler * During interrupt processing, all xcptcontext structures * should be valid for all tasks. That structure should * be modified to invoke sigdeliver() either on return * from (this) interrupt or on some subsequent context * switch to the recipient task. * (2) If not in an interrupt handler and the tcb is NOT * the currently executing task, then again just modify * the saved xcptcontext structure for the recipient * task so it will invoke sigdeliver when that task is * later resumed. * (3) If not in an interrupt handler and the tcb IS the * currently executing task -- just call the signal * handler now. * ****************************************************************************/ void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) { /* Refuse to handle nested signal actions */ sdbg("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver); if (!tcb->xcp.sigdeliver) { irqstate_t flags; /* Make sure that interrupts are disabled */ flags = irqsave(); /* First, handle some special cases when the signal is being delivered * to the currently executing task. */ sdbg("rtcb=0x%p current_regs=0x%p\n", g_readytorun.head, current_regs); if (tcb == (struct tcb_s*)g_readytorun.head) { /* CASE 1: We are not in an interrupt handler and a task is * signalling itself for some reason. */ if (!current_regs) { /* In this case just deliver the signal now. */ sigdeliver(tcb); } /* CASE 2: We are in an interrupt handler AND the interrupted * task is the same as the one that must receive the signal, then * we will have to modify the return state as well as the state * in the TCB. * * Hmmm... there looks like a latent bug here: The following logic * would fail in the strange case where we are in an interrupt * handler, the thread is signalling itself, but a context switch * to another task has occurred so that current_regs does not * refer to the thread at g_readytorun.head! */ else { /* Save the return lr and cpsr and one scratch register * These will be restored by the signal trampoline after * the signals have been delivered. */ tcb->xcp.sigdeliver = sigdeliver; tcb->xcp.saved_pc = current_regs[REG_PC]; tcb->xcp.saved_cpsr = current_regs[REG_CPSR]; /* Then set up to vector to the trampoline with interrupts * disabled */ current_regs[REG_PC] = (uint32_t)up_sigdeliver; current_regs[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT | PSR_F_BIT); /* And make sure that the saved context in the TCB is the same * as the interrupt return context. */ up_savestate(tcb->xcp.regs); } } /* Otherwise, we are (1) signaling a task is not running from an * interrupt handler or (2) we are not in an interrupt handler and the * running task is signalling some non-running task. */ else { /* Save the return lr and cpsr and one scratch register. These * will be restored by the signal trampoline after the signals * have been delivered. */ tcb->xcp.sigdeliver = sigdeliver; tcb->xcp.saved_pc = tcb->xcp.regs[REG_PC]; tcb->xcp.saved_cpsr = tcb->xcp.regs[REG_CPSR]; /* Then set up to vector to the trampoline with interrupts * disabled */ tcb->xcp.regs[REG_PC] = (uint32_t)up_sigdeliver; tcb->xcp.regs[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT | PSR_F_BIT); } irqrestore(flags); } } #endif /* !CONFIG_DISABLE_SIGNALS */