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nuttx-bb/nuttx/arch/mips/src/mips32/up_schedulesigaction.c

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/****************************************************************************
* arch/mips/src/mips32/up_schedulesigaction.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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 <nuttx/config.h>
#include <stdint.h>
#include <sched.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <arch/mips32/cp0.h>
#include "os_internal.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 'igdeliver' 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(_TCB *tcb, sig_deliver_t sigdeliver)
{
uint32_t status;
/* 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 == (_TCB*)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 EPC and STATUS registers. These will be
* restored by the signal trampoline after the signals have
* been delivered.
*/
tcb->xcp.sigdeliver = sigdeliver;
tcb->xcp.saved_epc = current_regs[REG_EPC];
tcb->xcp.saved_status = current_regs[REG_STATUS];
/* Then set up to vector to the trampoline with interrupts
* disabled
*/
current_regs[REG_EPC] = (uint32_t)up_sigdeliver;
status = current_regs[REG_STATUS];
status &= ~CP0_STATUS_IM_MASK;
status |= CP0_STATUS_IM_SWINTS;
current_regs[REG_STATUS] = status;
/* And make sure that the saved context in the TCB
* is the same as the interrupt return context.
*/
up_savestate(tcb->xcp.regs);
svdbg("PC/STATUS Saved: %08x/%08x New: %08x/%08x\n",
tcb->xcp.saved_epc, tcb->xcp.saved_status,
current_regs[REG_EPC], current_regs[REG_STATUS]);
}
}
/* 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 EPC and STATUS registers. These will be
* restored by the signal trampoline after the signals have
* been delivered.
*/
tcb->xcp.sigdeliver = sigdeliver;
tcb->xcp.saved_epc = tcb->xcp.regs[REG_EPC];
tcb->xcp.saved_status = tcb->xcp.regs[REG_STATUS];
/* Then set up to vector to the trampoline with interrupts
* disabled
*/
tcb->xcp.regs[REG_EPC] = (uint32_t)up_sigdeliver;
status = tcb->xcp.regs[REG_STATUS];
status &= ~CP0_STATUS_IM_MASK;
status |= CP0_STATUS_IM_SWINTS;
tcb->xcp.regs[REG_STATUS] = status;
svdbg("PC/STATUS Saved: %08x/%08x New: %08x/%08x\n",
tcb->xcp.saved_epc, tcb->xcp.saved_status,
tcb->xcp.regs[REG_EPC], tcb->xcp.regs[REG_STATUS]);
}
irqrestore(flags);
}
}
#endif /* !CONFIG_DISABLE_SIGNALS */
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