/**************************************************************************** * sched/addrenv/addrenv.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 #include #include #include #include #include #include #include "sched/sched.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /**************************************************************************** * Private Data ****************************************************************************/ /* This variable holds the current address environment. These contents are * _never_ NULL, besides when the system is started and there are only the * initial kernel mappings available. * * This must only be accessed with interrupts disabled. * * REVISIT: Try to get rid of this, global bookkeeping for this is dangerous. */ static FAR struct addrenv_s *g_addrenv[CONFIG_SMP_NCPUS]; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: addrenv_destroy * * Description: * Deferred service routine for destroying an address environment. This is * so that the heavy lifting is not done when the context is switching, or * from ISR. * * Input Parameters: * arg - Contains pointer to the address environment that is freed. * * Returned Value: * None. * ****************************************************************************/ static void addrenv_destroy(FAR void *arg) { FAR struct addrenv_s *addrenv = (FAR struct addrenv_s *)arg; /* Destroy the address environment */ up_addrenv_destroy(&addrenv->addrenv); /* Then finally release the memory */ kmm_free(addrenv); } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: addrenv_switch * * Description: * Instantiate the group address environment for the current thread at the * the head of the ready to run list. * * This function is called from platform-specific code after any context * switch (i.e., after any change in the thread at the head of the * ready-to-run list). This function will change the address environment * if the new thread is part of a different task group. * * Input Parameters: * tcb - The TCB of thread that needs an address environment. This should * be the TCB at the head of the ready-to-run list, but that is not * enough. * * Returned Value: * Zero (OK) is returned on success. A negated errno value is returned on * any failure. * * Assumptions: * This function should only be called within critical OS sections with * interrupts disabled. Interrupts are disabled internally just to be * certain, however. * ****************************************************************************/ int addrenv_switch(FAR struct tcb_s *tcb) { FAR struct addrenv_s *curr; FAR struct addrenv_s *next; irqstate_t flags; int cpu; int ret; /* NULL for the tcb means to use the TCB of the task at the head of the * ready to run list. */ if (!tcb) { tcb = this_task(); } DEBUGASSERT(tcb); next = tcb->addrenv_curr; /* Does the group have an address environment? */ if (!next) { /* No... just return perhaps leaving a different address environment * intact. */ return OK; } flags = enter_critical_section(); cpu = this_cpu(); curr = g_addrenv[cpu]; /* Are we going to change address environments? */ if (curr != next) { /* Yes.. Is there a current address environment in place? */ if (curr) { /* We need to flush the D-Cache and Invalidate the I-Cache for * the group whose environment is disappearing. */ up_addrenv_coherent(&curr->addrenv); } /* While the address environment is instantiated, it cannot be freed */ addrenv_take(next); /* Instantiate the new address environment (removing the old * environment in the process). For the case of kernel threads, * the old mappings will be removed and no new mappings will be * instantiated. */ ret = up_addrenv_select(&next->addrenv); if (ret < 0) { berr("ERROR: up_addrenv_select failed: %d\n", ret); } /* This is a safe spot to drop the current address environment */ if (curr) { addrenv_drop(curr, true); } /* Save the new, current address environment group */ g_addrenv[cpu] = next; } leave_critical_section(flags); return OK; } /**************************************************************************** * Name: addrenv_allocate * * Description: * Allocate an address environment for a new process. * * Input Parameters: * None * * Returned Value: * Pointer to the new address environment, or NULL if out of memory. * ****************************************************************************/ FAR struct addrenv_s *addrenv_allocate(void) { FAR struct addrenv_s *addrenv; addrenv = (FAR struct addrenv_s *)kmm_zalloc(sizeof(struct addrenv_s)); if (addrenv) { /* Take reference so this won't get freed */ addrenv->refs = 1; } return addrenv; } /**************************************************************************** * Name: addrenv_attach * * Description: * Attach address environment to a newly created group. Called by exec() * right before injecting the new process into the system. * * Input Parameters: * tcb - The tcb of the newly loaded task. * addrenv - The address environment that is attached. * * Returned Value: * This is a NuttX internal function so it follows the convention that * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int addrenv_attach(FAR struct tcb_s *tcb, FAR struct addrenv_s *addrenv) { /* Attach the address environment */ tcb->addrenv_own = addrenv; tcb->addrenv_curr = tcb->addrenv_own; return OK; } /**************************************************************************** * Name: addrenv_join * * Description: * Join the parent process's address environment. * * Input Parameters: * ptcb - The tcb of the parent process * tcb - The tcb of the child process * * Returned Value: * This is a NuttX internal function so it follows the convention that * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int addrenv_join(FAR struct tcb_s *ptcb, FAR struct tcb_s *tcb) { int ret; ret = up_addrenv_attach(ptcb, tcb); if (ret < 0) { berr("ERROR: up_addrenv_attach failed: %d\n", ret); return ret; } /* Take a reference to the address environment */ addrenv_take(ptcb->addrenv_own); /* Share the parent's address environment */ tcb->addrenv_own = ptcb->addrenv_own; tcb->addrenv_curr = tcb->addrenv_own; return OK; } /**************************************************************************** * Name: addrenv_leave * * Description: * Leave a process's address environment. * * Input Parameters: * tcb - The tcb of the process * * Returned Value: * This is a NuttX internal function so it follows the convention that * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int addrenv_leave(FAR struct tcb_s *tcb) { int ret; /* Detach from the address environment */ ret = up_addrenv_detach(tcb); /* Then drop the address environment */ addrenv_drop(tcb->addrenv_own, false); tcb->addrenv_own = NULL; return ret; } /**************************************************************************** * Name: addrenv_select * * Description: * Temporarily select a different address environment for the currently * running process. * * Input Parameters: * addrenv - The address environment. * * Returned Value: * This is a NuttX internal function so it follows the convention that * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int addrenv_select(FAR struct addrenv_s *addrenv) { FAR struct tcb_s *tcb = this_task(); addrenv_take(addrenv); tcb->addrenv_curr = addrenv; return addrenv_switch(tcb); } /**************************************************************************** * Name: addrenv_restore * * Description: * Switch back to the procces's own address environment. * * Input Parameters: * None * * Returned Value: * This is a NuttX internal function so it follows the convention that * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int addrenv_restore(void) { FAR struct tcb_s *tcb = this_task(); addrenv_give(tcb->addrenv_curr); tcb->addrenv_curr = tcb->addrenv_own; return addrenv_switch(tcb); } /**************************************************************************** * Name: addrenv_take * * Description: * Take a reference to an address environment. * * Input Parameters: * addrenv - The address environment. * * Returned Value: * None. * ****************************************************************************/ void addrenv_take(FAR struct addrenv_s *addrenv) { irqstate_t flags = enter_critical_section(); addrenv->refs++; leave_critical_section(flags); } /**************************************************************************** * Name: addrenv_give * * Description: * Give back a reference to an address environment, obtaining the resulting * reference counter as returned value. * * Input Parameters: * addrenv - The address environment. * * Returned Value: * Remaining reference count. * ****************************************************************************/ int addrenv_give(FAR struct addrenv_s *addrenv) { irqstate_t flags; int refs; flags = enter_critical_section(); refs = --addrenv->refs; leave_critical_section(flags); return refs; } /**************************************************************************** * Name: addrenv_drop * * Description: * Drop an address environment. * * Input Parameters: * addrenv - The address environment. * deferred - yes: The address environment should be dropped by the worker * no: The address environment can be dropped at once * * Returned Value: * None. * ****************************************************************************/ void addrenv_drop(FAR struct addrenv_s *addrenv, bool deferred) { if (addrenv == NULL) { /* No address environment, get out */ return; } /* If no more users, the address environment can be dropped */ if (addrenv_give(addrenv) == 0) { /* Defer dropping if requested to do so, otherwise drop at once */ if (deferred) { /* Let the DSR do the heavy lifting */ work_queue(LPWORK, &addrenv->work, addrenv_destroy, addrenv, 0); } else { addrenv_destroy(addrenv); } } }