360 lines
12 KiB
C
360 lines
12 KiB
C
/****************************************************************************
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* arch/arm/src/armv7-a/arm_schedulesigaction.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <stdint.h>
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#include <sched.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/irq.h>
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#include <nuttx/arch.h>
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#include "arm.h"
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#include "sched/sched.h"
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#include "arm_internal.h"
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#include "arm_arch.h"
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#include "irq/irq.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: up_schedule_sigaction
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*
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* Description:
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* This function is called by the OS when one or more
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* signal handling actions have been queued for execution.
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* The architecture specific code must configure things so
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* that the 'sigdeliver' callback is executed on the thread
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* specified by 'tcb' as soon as possible.
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*
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* This function may be called from interrupt handling logic.
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*
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* This operation should not cause the task to be unblocked
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* nor should it cause any immediate execution of sigdeliver.
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* Typically, a few cases need to be considered:
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*
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* (1) This function may be called from an interrupt handler
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* During interrupt processing, all xcptcontext structures
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* should be valid for all tasks. That structure should
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* be modified to invoke sigdeliver() either on return
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* from (this) interrupt or on some subsequent context
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* switch to the recipient task.
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* (2) If not in an interrupt handler and the tcb is NOT
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* the currently executing task, then again just modify
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* the saved xcptcontext structure for the recipient
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* task so it will invoke sigdeliver when that task is
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* later resumed.
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* (3) If not in an interrupt handler and the tcb IS the
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* currently executing task -- just call the signal
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* handler now.
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*
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* Assumptions:
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* Called from critical section
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*
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****************************************************************************/
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#ifndef CONFIG_SMP
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void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
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{
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sinfo("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver);
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/* Refuse to handle nested signal actions */
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if (!tcb->xcp.sigdeliver)
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{
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/* First, handle some special cases when the signal is being delivered
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* to task that is currently executing on this CPU.
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*/
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sinfo("rtcb=0x%p CURRENT_REGS=0x%p\n", this_task(), CURRENT_REGS);
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if (tcb == this_task())
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{
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/* CASE 1: We are not in an interrupt handler and a task is
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* signaling itself for some reason.
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*/
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if (!CURRENT_REGS)
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{
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/* In this case just deliver the signal now.
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* REVISIT: Signal handler will run in a critical section!
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*/
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sigdeliver(tcb);
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}
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/* CASE 2: We are in an interrupt handler AND the interrupted
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* task is the same as the one that must receive the signal, then
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* we will have to modify the return state as well as the state
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* in the TCB.
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*
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* Hmmm... there looks like a latent bug here: The following logic
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* would fail in the strange case where we are in an interrupt
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* handler, the thread is signaling itself, but a context switch
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* to another task has occurred so that CURRENT_REGS does not
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* refer to the thread of this_task()!
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*/
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else
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{
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/* Save the return lr and cpsr and one scratch register
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* These will be restored by the signal trampoline after
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* the signals have been delivered.
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*/
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tcb->xcp.sigdeliver = sigdeliver;
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tcb->xcp.saved_pc = CURRENT_REGS[REG_PC];
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tcb->xcp.saved_cpsr = CURRENT_REGS[REG_CPSR];
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/* Then set up to vector to the trampoline with interrupts
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* disabled
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*/
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CURRENT_REGS[REG_PC] = (uint32_t)arm_sigdeliver;
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CURRENT_REGS[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT |
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PSR_F_BIT);
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#ifdef CONFIG_ARM_THUMB
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CURRENT_REGS[REG_CPSR] |= PSR_T_BIT;
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#endif
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/* And make sure that the saved context in the TCB is the same
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* as the interrupt return context.
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*/
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arm_savestate(tcb->xcp.regs);
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}
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}
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/* Otherwise, we are (1) signaling a task is not running from an
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* interrupt handler or (2) we are not in an interrupt handler and the
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* running task is signaling some other non-running task.
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*/
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else
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{
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/* Save the return lr and cpsr and one scratch register. These
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* will be restored by the signal trampoline after the signals
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* have been delivered.
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*/
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tcb->xcp.sigdeliver = sigdeliver;
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tcb->xcp.saved_pc = tcb->xcp.regs[REG_PC];
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tcb->xcp.saved_cpsr = tcb->xcp.regs[REG_CPSR];
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/* Then set up to vector to the trampoline with interrupts
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* disabled
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*/
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tcb->xcp.regs[REG_PC] = (uint32_t)arm_sigdeliver;
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tcb->xcp.regs[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT | PSR_F_BIT);
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#ifdef CONFIG_ARM_THUMB
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tcb->xcp.regs[REG_CPSR] |= PSR_T_BIT;
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#endif
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}
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}
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}
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#endif /* !CONFIG_SMP */
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#ifdef CONFIG_SMP
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void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
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{
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int cpu;
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int me;
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sinfo("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver);
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/* Refuse to handle nested signal actions */
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if (!tcb->xcp.sigdeliver)
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{
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/* First, handle some special cases when the signal is being delivered
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* to task that is currently executing on any CPU.
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*/
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sinfo("rtcb=0x%p CURRENT_REGS=0x%p\n", this_task(), CURRENT_REGS);
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if (tcb->task_state == TSTATE_TASK_RUNNING)
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{
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me = this_cpu();
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cpu = tcb->cpu;
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/* CASE 1: We are not in an interrupt handler and a task is
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* signaling itself for some reason.
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*/
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if (cpu == me && !CURRENT_REGS)
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{
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/* In this case just deliver the signal now.
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* REVISIT: Signal handler will run in a critical section!
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*/
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sigdeliver(tcb);
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}
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/* CASE 2: The task that needs to receive the signal is running.
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* This could happen if the task is running on another CPU OR if
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* we are in an interrupt handler and the task is running on this
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* CPU. In the former case, we will have to PAUSE the other CPU
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* first. But in either case, we will have to modify the return
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* state as well as the state in the TCB.
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*/
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else
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{
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/* If we signaling a task running on the other CPU, we have
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* to PAUSE the other CPU.
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*/
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if (cpu != me)
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{
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/* Pause the CPU */
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up_cpu_pause(cpu);
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/* Wait while the pause request is pending */
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while (up_cpu_pausereq(cpu))
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{
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}
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/* Now tcb on the other CPU can be accessed safely */
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/* Copy tcb->xcp.regs to tcp.xcp.saved. These will be
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* restored by the signal trampoline after the signal has
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* been delivered.
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*/
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tcb->xcp.sigdeliver = sigdeliver;
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tcb->xcp.saved_pc = tcb->xcp.regs[REG_PC];
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tcb->xcp.saved_cpsr = tcb->xcp.regs[REG_CPSR];
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/* Then set up to vector to the trampoline with interrupts
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* disabled
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*/
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tcb->xcp.regs[REG_PC] = (uint32_t)arm_sigdeliver;
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tcb->xcp.regs[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT |
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PSR_F_BIT);
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#ifdef CONFIG_ARM_THUMB
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tcb->xcp.regs[REG_CPSR] |= PSR_T_BIT;
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#endif
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}
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else
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{
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/* tcb is running on the same CPU */
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/* Save the return PC, CPSR and either the BASEPRI or
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* PRIMASK registers (and perhaps also the LR). These will
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* be restored by the signal trampoline after the signal
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* has been delivered.
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*/
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tcb->xcp.sigdeliver = (FAR void *)sigdeliver;
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tcb->xcp.saved_pc = CURRENT_REGS[REG_PC];
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tcb->xcp.saved_cpsr = CURRENT_REGS[REG_CPSR];
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/* Then set up vector to the trampoline with interrupts
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* disabled. The kernel-space trampoline must run in
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* privileged thread mode.
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*/
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CURRENT_REGS[REG_PC] = (uint32_t)arm_sigdeliver;
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CURRENT_REGS[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT |
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PSR_F_BIT);
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#ifdef CONFIG_ARM_THUMB
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CURRENT_REGS[REG_CPSR] |= PSR_T_BIT;
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#endif
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/* And make sure that the saved context in the TCB is the
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* same as the interrupt return context.
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*/
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arm_savestate(tcb->xcp.regs);
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}
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/* Increment the IRQ lock count so that when the task is
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* restarted, it will hold the IRQ spinlock.
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*/
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DEBUGASSERT(tcb->irqcount < INT16_MAX);
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tcb->irqcount++;
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/* NOTE: If the task runs on another CPU(cpu), adjusting
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* global IRQ controls will be done in the pause handler
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* on the CPU(cpu) by taking a critical section.
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* If the task is scheduled on this CPU(me), do nothing
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* because this CPU already took a critical section
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*/
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/* RESUME the other CPU if it was PAUSED */
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if (cpu != me)
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{
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up_cpu_resume(cpu);
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}
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}
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}
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/* Otherwise, we are (1) signaling a task is not running from an
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* interrupt handler or (2) we are not in an interrupt handler and the
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* running task is signaling some other non-running task.
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*/
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else
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{
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/* Save the return lr and cpsr and one scratch register. These
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* will be restored by the signal trampoline after the signals
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* have been delivered.
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*/
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tcb->xcp.sigdeliver = sigdeliver;
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tcb->xcp.saved_pc = tcb->xcp.regs[REG_PC];
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tcb->xcp.saved_cpsr = tcb->xcp.regs[REG_CPSR];
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/* Increment the IRQ lock count so that when the task is restarted,
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* it will hold the IRQ spinlock.
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*/
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DEBUGASSERT(tcb->irqcount < INT16_MAX);
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tcb->irqcount++;
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/* Then set up to vector to the trampoline with interrupts
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* disabled
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*/
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tcb->xcp.regs[REG_PC] = (uint32_t)arm_sigdeliver;
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tcb->xcp.regs[REG_CPSR] = (PSR_MODE_SVC | PSR_I_BIT | PSR_F_BIT);
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#ifdef CONFIG_ARM_THUMB
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tcb->xcp.regs[REG_CPSR] |= PSR_T_BIT;
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#endif
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}
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}
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}
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#endif /* CONFIG_SMP */
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