7b9978883c
The current context save implementation saves registers of each task to xcp context, which is unnecessary because most of the arm registers are already saved in the task stack, this commit replace the xcp context with stack context to improve context switching performance and reduce the tcb space occupation of tcb instance. Signed-off-by: chao.an <anchao@xiaomi.com>
149 lines
4.6 KiB
C
149 lines
4.6 KiB
C
/****************************************************************************
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* arch/arm/src/armv7-a/arm_sigdeliver.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 <nuttx/board.h>
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#include <arch/board/board.h>
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#include "sched/sched.h"
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#include "arm_internal.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: arm_sigdeliver
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*
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* Description:
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* This is the a signal handling trampoline. When a signal action was
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* posted. The task context was mucked with and forced to branch to this
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* location with interrupts disabled.
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*
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****************************************************************************/
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void arm_sigdeliver(void)
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{
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struct tcb_s *rtcb = this_task();
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uint32_t *regs = rtcb->xcp.saved_regs;
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#ifdef CONFIG_SMP
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/* In the SMP case, we must terminate the critical section while the signal
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* handler executes, but we also need to restore the irqcount when the
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* we resume the main thread of the task.
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*/
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int16_t saved_irqcount;
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#endif
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board_autoled_on(LED_SIGNAL);
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sinfo("rtcb=%p sigdeliver=%p sigpendactionq.head=%p\n",
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rtcb, rtcb->xcp.sigdeliver, rtcb->sigpendactionq.head);
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DEBUGASSERT(rtcb->xcp.sigdeliver != NULL);
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#ifdef CONFIG_SMP
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/* In the SMP case, up_schedule_sigaction(0) will have incremented
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* 'irqcount' in order to force us into a critical section. Save the
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* pre-incremented irqcount.
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*/
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saved_irqcount = rtcb->irqcount - 1;
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DEBUGASSERT(saved_irqcount >= 0);
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/* Now we need call leave_critical_section() repeatedly to get the irqcount
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* to zero, freeing all global spinlocks that enforce the critical section.
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*/
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do
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{
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leave_critical_section(regs[REG_CPSR]);
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}
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while (rtcb->irqcount > 0);
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#endif /* CONFIG_SMP */
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#ifndef CONFIG_SUPPRESS_INTERRUPTS
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/* Then make sure that interrupts are enabled. Signal handlers must always
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* run with interrupts enabled.
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*/
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up_irq_enable();
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#endif
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/* Deliver the signal */
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((sig_deliver_t)rtcb->xcp.sigdeliver)(rtcb);
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/* Output any debug messages BEFORE restoring errno (because they may
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* alter errno), then disable interrupts again and restore the original
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* errno that is needed by the user logic (it is probably EINTR).
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*
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* I would prefer that all interrupts are disabled when
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* arm_fullcontextrestore() is called, but that may not be necessary.
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*/
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sinfo("Resuming\n");
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#ifdef CONFIG_SMP
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/* Restore the saved 'irqcount' and recover the critical section
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* spinlocks.
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*/
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DEBUGASSERT(rtcb->irqcount == 0);
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while (rtcb->irqcount < saved_irqcount)
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{
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enter_critical_section();
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}
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#endif
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#ifndef CONFIG_SUPPRESS_INTERRUPTS
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up_irq_save();
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#endif
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/* Modify the saved return state with the actual saved values in the
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* TCB. This depends on the fact that nested signal handling is
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* not supported. Therefore, these values will persist throughout the
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* signal handling action.
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*
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* Keeping this data in the TCB resolves a security problem in protected
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* and kernel mode: The regs[] array is visible on the user stack and
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* could be modified by a hostile program.
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*/
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rtcb->xcp.sigdeliver = NULL; /* Allows next handler to be scheduled */
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/* Then restore the correct state for this thread of execution. */
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board_autoled_off(LED_SIGNAL);
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arm_fullcontextrestore(regs);
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}
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