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arm_schedulesigaction.c
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arm_schedulesigaction.c
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/****************************************************************************
* arch/arm/src/armv7-m/arm_schedulesigaction.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <sched.h>
#include <assert.h>
#include <debug.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include <arch/armv7-m/nvicpri.h>
#include "psr.h"
#include "exc_return.h"
#include "sched/sched.h"
#include "arm_internal.h"
#include "irq/irq.h"
/****************************************************************************
* 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.
*
* Assumptions:
* Called from critical section
*
****************************************************************************/
void up_schedule_sigaction(struct tcb_s *tcb, sig_deliver_t sigdeliver)
{
sinfo("tcb=%p sigdeliver=%p\n", tcb, sigdeliver);
DEBUGASSERT(tcb != NULL && sigdeliver != NULL);
/* Refuse to handle nested signal actions */
if (tcb->xcp.sigdeliver == NULL)
{
tcb->xcp.sigdeliver = sigdeliver;
/* First, handle some special cases when the signal is being delivered
* to the currently executing task.
*/
sinfo("rtcb=%p current_regs=%p\n", this_task(),
this_task()->xcp.regs);
if (tcb == this_task() && !up_interrupt_context())
{
/* In this case just deliver the signal now.
* REVISIT: Signal handle will run in a critical section!
*/
sigdeliver(tcb);
tcb->xcp.sigdeliver = NULL;
}
else
{
/* 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.
*/
/* If we signaling a task running on the other CPU, we have
* to PAUSE the other CPU.
*/
#ifdef CONFIG_SMP
int cpu = tcb->cpu;
int me = this_cpu();
if (cpu != me)
{
/* Pause the CPU */
up_cpu_pause(cpu);
}
#endif
/* 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.
*/
/* Save the current register context location */
tcb->xcp.saved_regs = tcb->xcp.regs;
/* Duplicate the register context. These will be
* restored by the signal trampoline after the signal has been
* delivered.
*/
tcb->xcp.regs = (void *)
((uint32_t)tcb->xcp.regs -
XCPTCONTEXT_SIZE);
memcpy(tcb->xcp.regs, tcb->xcp.saved_regs, XCPTCONTEXT_SIZE);
tcb->xcp.regs[REG_SP] = (uint32_t)tcb->xcp.regs +
XCPTCONTEXT_SIZE;
/* Then set up to vector to the trampoline with interrupts
* disabled. We must already be in privileged thread mode to be
* here.
*/
tcb->xcp.regs[REG_PC] = (uint32_t)arm_sigdeliver;
#ifdef CONFIG_ARMV7M_USEBASEPRI
tcb->xcp.regs[REG_BASEPRI] = NVIC_SYSH_DISABLE_PRIORITY;
#else
tcb->xcp.regs[REG_PRIMASK] = 1;
#endif
tcb->xcp.regs[REG_XPSR] = ARMV7M_XPSR_T;
#ifdef CONFIG_BUILD_PROTECTED
tcb->xcp.regs[REG_LR] = EXC_RETURN_THREAD;
tcb->xcp.regs[REG_EXC_RETURN] = EXC_RETURN_THREAD;
tcb->xcp.regs[REG_CONTROL] = getcontrol() & ~CONTROL_NPRIV;
#endif
#ifdef CONFIG_SMP
/* RESUME the other CPU if it was PAUSED */
if (cpu != me)
{
up_cpu_resume(cpu);
}
#endif
}
}
}