/**************************************************************************** * arch/arm/src/armv7-a/arm_schedulesigaction.c * * Copyright (C) 2013, 2015-2018 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 #include "arm.h" #include "sched/sched.h" #include "up_internal.h" #include "up_arch.h" #include "irq/irq.h" #ifndef CONFIG_DISABLE_SIGNALS /**************************************************************************** * 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. * ****************************************************************************/ #ifndef CONFIG_SMP void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) { irqstate_t flags; sinfo("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver); /* Make sure that interrupts are disabled */ flags = enter_critical_section(); /* Refuse to handle nested signal actions */ if (!tcb->xcp.sigdeliver) { /* First, handle some special cases when the signal is being delivered * to task that is currently executing on this CPU. */ sinfo("rtcb=0x%p CURRENT_REGS=0x%p\n", this_task(), CURRENT_REGS); if (tcb == this_task()) { /* CASE 1: We are not in an interrupt handler and a task is * signaling 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 signaling itself, but a context switch * to another task has occurred so that CURRENT_REGS does not * refer to the thread of this_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 = 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 signaling some other 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); } } leave_critical_section(flags); } #endif /* !CONFIG_SMP */ #ifdef CONFIG_SMP void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver) { irqstate_t flags; int cpu; int me; sinfo("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver); /* Make sure that interrupts are disabled */ flags = enter_critical_section(); /* Refuse to handle nested signal actions */ if (!tcb->xcp.sigdeliver) { /* First, handle some special cases when the signal is being delivered * to task that is currently executing on any CPU. */ sinfo("rtcb=0x%p CURRENT_REGS=0x%p\n", this_task(), CURRENT_REGS); if (tcb->task_state == TSTATE_TASK_RUNNING) { me = this_cpu(); cpu = tcb->cpu; /* CASE 1: We are not in an interrupt handler and a task is * signaling itself for some reason. */ if (cpu == me && !CURRENT_REGS) { /* In this case just deliver the signal now. */ sigdeliver(tcb); } /* CASE 2: The task that needs to receive the signal is running. * This could happen if the task is running on another CPU OR if * we are in an interrupt handler and the task is running on this * CPU. In the former case, we will have to PAUSE the other CPU * first. But in either case, we will have to modify the return * state as well as the state in the TCB. */ else { /* If we signaling a task running on the other CPU, we have * to PAUSE the other CPU. */ if (cpu != me) { /* Pause the CPU */ up_cpu_pause(cpu); /* Wait while the pause request is pending */ while (up_cpu_pausereq(cpu)) { } /* Now tcb on the other CPU can be accessed safely */ /* Copy tcb->xcp.regs to tcp.xcp.saved. These will be restored * by the signal trampoline after the signal has 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); } else { /* tcb is running on the same CPU */ /* Save the return PC, CPSR and either the BASEPRI or PRIMASK * registers (and perhaps also the LR). These will be * restored by the signal trampoline after the signal has been * delivered. */ tcb->xcp.sigdeliver = (FAR void *)sigdeliver; tcb->xcp.saved_pc = CURRENT_REGS[REG_PC]; tcb->xcp.saved_cpsr = CURRENT_REGS[REG_CPSR]; /* Then set up vector to the trampoline with interrupts * disabled. The kernel-space trampoline must run in * privileged thread mode. */ 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); } /* Increment the IRQ lock count so that when the task is restarted, * it will hold the IRQ spinlock. */ DEBUGASSERT(tcb->irqcount < INT16_MAX); tcb->irqcount++; /* In an SMP configuration, the interrupt disable logic also * involves spinlocks that are configured per the TCB irqcount * field. This is logically equivalent to enter_critical_section(). * The matching call to leave_critical_section() will be * performed in up_sigdeliver(). */ spin_setbit(&g_cpu_irqset, cpu, &g_cpu_irqsetlock, &g_cpu_irqlock); /* RESUME the other CPU if it was PAUSED */ if (cpu != me) { up_cpu_resume(cpu); } } } /* 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 signaling some other 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]; /* Increment the IRQ lock count so that when the task is restarted, * it will hold the IRQ spinlock. */ DEBUGASSERT(tcb->irqcount < INT16_MAX); tcb->irqcount++; /* 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); } } leave_critical_section(flags); } #endif /* CONFIG_SMP */ #endif /* !CONFIG_DISABLE_SIGNALS */