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incubator-nuttx/include/nuttx/page.h

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/****************************************************************************
* include/nuttx/page.h
* This file defines interfaces used to support NuttX On-Demand Paging.
*
* 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.
*
****************************************************************************/
#ifndef __INCLUDE_NUTTX_PAGE_H
#define __INCLUDE_NUTTX_PAGE_H
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#ifndef __ASSEMBLY__
# include <stdbool.h>
# include <nuttx/sched.h>
#endif
#ifdef CONFIG_PAGING
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Configuration ************************************************************/
/* CONFIG_PAGING_PAGESIZE - The size of one managed page. This must be a
* value supported by the processor's memory management unit. The
* following may need to be extended to support additional page sizes at
* some point.
*/
#if CONFIG_PAGING_PAGESIZE == 1024
# define PAGESIZE 1024
# define PAGESHIFT 10
# define PAGEMASK 0x000003ff
#elif CONFIG_PAGING_PAGESIZE == 4096
# define PAGESIZE 4096
# define PAGESHIFT 12
# define PAGEMASK 0x00000fff
#else
# error "Need extended definitions for CONFIG_PAGING_PAGESIZE"
#endif
/* Alignment macros */
#define PG_ALIGNDOWN(addr) ((addr) & ~PAGEMASK)
#define PG_ALIGNUP(addr) (((addr) + PAGEMASK) & ~PAGEMASK)
/* CONFIG_PAGING_NLOCKED - This is the number of locked pages in the memory
* map. The size of locked address region will then be given by
* PG_LOCKED_SIZE. These values applies to both physical and virtual memory
* regions.
*/
#define PG_LOCKED_SIZE (CONFIG_PAGING_NLOCKED << PAGESHIFT)
/* CONFIG_PAGING_LOCKED_P/VBASE - May be defined to determine the base
* address of the locked page regions (lowest in memory). If neither
* are defined, then this logic will be set the bases to CONFIG_RAM_START
* and CONFIG_RAM_VSTART (i.e., it assumes that the base address of the
* locked region is at the beginning of RAM).
*
* NOTE: In some architectures, it may be necessary to take some memory
* from the beginning of this region for vectors or for a page table.
* In such cases, either (1) CONFIG_PAGING_LOCKED_P/VBASE might take that
* into consideration to prevent overlapping the locked memory region
* and the system data at the beginning of SRAM, (2) you extend
* CONFIG_PAGING_NLOCKED include these pages at the beginning
* of memory and map let them be mapped read-only.
*/
#if defined(CONFIG_PAGING_LOCKED_PBASE) && defined(CONFIG_PAGING_LOCKED_VBASE)
# define PG_LOCKED_PBASE CONFIG_PAGING_LOCKED_PBASE
# define PG_LOCKED_VBASE CONFIG_PAGING_LOCKED_VBASE
#else
# define PG_LOCKED_PBASE CONFIG_RAM_START
# define PG_LOCKED_VBASE CONFIG_RAM_VSTART
#endif
#define PG_LOCKED_PEND (PG_LOCKED_PBASE + PG_LOCKED_SIZE)
#define PG_LOCKED_VEND (PG_LOCKED_VBASE + PG_LOCKED_SIZE)
#if (PG_LOCKED_PBASE & PAGEMASK) != 0 || (PG_LOCKED_VBASE & PAGEMASK) != 0
# error "Base address of the locked region is not page aligned"
#endif
/* CONFIG_PAGING_NPPAGED - This is the number of physical pages available to
* support the paged text region.
* CONFIG_PAGING_NVPAGED - This actual size of the virtual paged text region
* (in pages). This is also the number of virtual pages required to span
* the entire paged region. The on-demand paging feature is intended to
* support only the case where the virtual paged text area is much larger
* the available physical pages. Otherwise, why would you enable on-demand
* paging?
*/
#if CONFIG_PAGING_NPPAGED >= CONFIG_PAGING_NVPAGED
# error "CONFIG_PAGING_NPPAGED must be less than CONFIG_PAGING_NVPAGED"
#endif
/* The size of physical and virtual paged address regions will then be: */
#define PG_PAGED_PSIZE (CONFIG_PAGING_NPPAGED << PAGESHIFT)
#define PG_PAGED_VSIZE (CONFIG_PAGING_NVPAGED << PAGESHIFT)
/* This positions the paging Read-Only text region. If the configuration
* did not override the default, the paged region will immediately follow
* the locked region.
*/
#if defined(CONFIG_PAGING_LOCKED_PBASE) && defined(CONFIG_PAGING_LOCKED_VBASE)
# define PG_PAGED_PBASE CONFIG_PAGING_LOCKED_PBASE
# define PG_PAGED_VBASE CONFIG_PAGING_LOCKED_VBASE
#else
# define PG_PAGED_PBASE PG_LOCKED_PEND
# define PG_PAGED_VBASE PG_LOCKED_VEND
#endif
#define PG_PAGED_PEND (PG_PAGED_PBASE + PG_PAGED_PSIZE)
#define PG_PAGED_VEND (PG_PAGED_VBASE + PG_PAGED_VSIZE)
/* Size and description of the overall text section. The number of
* pages in the text section is the sum of the number of pages in
* both the locked and paged regions. The base of the text section
* is the base of the locked region.
*/
#define PG_TEXT_NPPAGES (CONFIG_PAGING_NLOCKED + CONFIG_PAGING_NPPAGED)
#define PG_TEXT_NVPAGES (CONFIG_PAGING_NLOCKED + CONFIG_PAGING_NVPAGED)
#define PG_TEXT_PSIZE (PG_TEXT_NPPAGES << PAGESHIFT)
#define PG_TEXT_VSIZE (PG_TEXT_NVPAGES << PAGESHIFT)
#define PG_TEXT_PBASE PG_LOCKED_PBASE
#define PG_TEXT_VBASE PG_LOCKED_VBASE
/* CONFIG_PAGING_NDATA - This is the number of data pages in the memory
* map. The data region will extend to the end of RAM unless overridden
* by a setting in the configuration file.
*
* NOTE: In some architectures, it may be necessary to take some memory
* from the end of RAM for page tables or other system usage. The
* configuration settings and linker directives must be cognizant of that:
* CONFIG_PAGING_NDATA should be defined to prevent the data region from
* extending all the way to the end of memory.
*/
#define PG_RAM_PAGES (CONFIG_RAM_SIZE >> PAGESHIFT)
#ifdef CONFIG_PAGING_NDATA
# define PG_DATA_NPAGES CONFIG_PAGING_NDATA
#elif PG_RAM_PAGES > PG_TEXT_NPPAGES
# define PG_DATA_NPAGES (PG_RAM_PAGES - PG_TEXT_NPAGES)
#else
# error "Not enough memory for this page layout"
#endif
#define PG_DATA_SIZE (PG_DATA_NPAGES << PAGESHIFT)
/* This positions the Read/Write data region. If the configuration
* did not override the default, the paged region will immediately follow
* the paged region and will extend to the end of memory.
*/
#if defined(CONFIG_PAGING_DATA_PBASE) && defined(CONFIG_PAGING_DATA_VBASE)
# define PG_DATA_PBASE CONFIG_PAGING_DATA_PBASE
# define PG_DATA_VBASE CONFIG_PAGING_DATA_VBASE
#else
# define PG_DATA_PBASE PG_LOCKED_PEND
# define PG_DATA_VBASE PG_LOCKED_VEND
#endif
/* CONFIG_PAGING_DEFPRIO - The default, minimum priority of the page fill
* worker thread. The priority of the page fill work thread will be
* boosted boosted dynamically so that it matches the priority of the
* task on behalf of which it performs the fill. This defines the
* minimum priority that will be used. Default: 50.
* CONFIG_PAGING_STACKSIZE - Defines the size of the allocated stack
* for the page fill worker thread. Default: 1024.
* CONFIG_PAGING_BLOCKINGFILL - The architecture specific up_fillpage()
* function may be blocking or non-blocking. If defined, this setting
* indicates that the up_fillpage() implementation will block until
* the transfer is completed. Default: Undefined (non-blocking).
* CONFIG_PAGING_WORKPERIOD - The page fill worker thread will wake
* periodically even if there is no mapping to do. This selection controls
* that wake-up period (in microseconds). This wake-up a failsafe that
* will handle any cases where a single is lost (that would really be a bug
* and shouldn't happen!) and also supports timeouts for case of
* non-blocking, asynchronous fills (see CONFIG_PAGING_TIMEOUT_TICKS).
* CONFIG_PAGING_TIMEOUT_TICKS - If defined, the implementation will monitor
* the (asynchronous) page fill logic. If the fill takes longer than this
* number if microseconds, then a fatal error will be declared.
* Default: No timeouts monitored.
*/
/****************************************************************************
* Public Data
****************************************************************************/
#ifndef __ASSEMBLY__
#undef EXTERN
#if defined(__cplusplus)
#define EXTERN extern "C"
extern "C"
{
#else
#define EXTERN extern
#endif
/****************************************************************************
* Public Functions -- Provided by common paging logic to architecture-
* specific logic.
****************************************************************************/
/****************************************************************************
* Name: pg_miss
*
* Description:
* This function is called from architecture-specific memory segmentation
* fault handling logic. This function will perform the following
* operations:
*
* 1) Sanity checking.
* - ASSERT if the currently executing task is the page fill worker
* thread. The page fill worker thread is how the page fault
* is resolved and all logic associated with the page fill worker
* must be "locked" and always present in memory.
* 2) Block the currently executing task.
* - Call up_block_task() to block the task at the head of the ready-
* to-run list. This should cause an interrupt level context switch
* to the next highest priority task.
* - The blocked task will be marked with state TSTATE_WAIT_PAGEFILL
* and will be retained in the g_waitingforfill prioritized task
* list.
* 3) Boost the page fill worker thread priority.
* - Check the priority of the task at the head of the g_waitingforfill
* list. If the priority of that task is higher than the current
* priority of the page fill worker thread, then boost the priority
* of the page fill worker thread to that priority.
* 4) Signal the page fill worker thread.
* - Is there a page fill pending? If not then signal the worker
* thread to start working on the queued page fill requests.
*
* Input Parameters:
* None - The head of the ready-to-run list is assumed to be task that
* caused the exception.
*
* Returned Value:
* None - Either this function function succeeds or an assertion occurs.
*
* Assumptions:
* - It is assumed that this function is called from the level of an
* exception handler and that all interrupts are disabled.
* - It is assumed that currently executing task (the one at the head of
* the ready-to-run list) is the one that cause the fault. This will
* always be true unless the page fault occurred in an interrupt handler.
* Interrupt handling logic must always be present and "locked" into
* memory.
* - The chip-specific page fault exception handler has already verified
* that the exception did not occur from interrupt/exception handling
* logic.
* - As mentioned above, the task causing the page fault must not be the
* page fill worker thread because that is the only way to complete the
* page fill.
*
* NOTES:
* 1. One way to accomplish this would be a two pass link phase:
* - In the first phase, create a partially linked objected containing
* all interrupt/exception handling logic, the page fill worker thread
* plus all parts of the IDLE thread (which must always be available
* for execution).
* - All of the .text and .rodata sections of this partial link should
* be collected into a single section.
* - The second link would link the partially linked object along with
* the remaining object to produce the final binary. The linker
* script should position the "special" section so that it lies
* in a reserved, "non-swappable" region.
*
****************************************************************************/
void pg_miss(void);
/****************************************************************************
* Public Functions -- Provided by architecture-specific logic to common
* paging logic.
****************************************************************************/
/****************************************************************************
* Name: up_checkmapping()
*
* Description:
* The function up_checkmapping() returns an indication if the page fill
* still needs to performed or not. In certain conditions, the page fault
* may occur on several threads and be queued multiple times. This function
* will prevent the same page from be filled multiple times.
*
* Input Parameters:
* tcb - A reference to the task control block of the task that we believe
* needs to have a page fill. Architecture-specific logic can
* retrieve page fault information from the architecture-specific
* context information in this TCB and can consult processor
* resources (page tables or TLBs or ???) to determine if the fill
* still needs to be performed or not.
*
* Returned Value:
* This function will return true if the mapping is in place and false
* if the mapping is still needed. Errors encountered should be
* interpreted as fatal.
*
* Assumptions:
* - This function is called from the normal tasking context (but with
* interrupts disabled). The implementation must take whatever actions
* are necessary to assure that the operation is safe within this
* context.
*
****************************************************************************/
bool up_checkmapping(FAR struct tcb_s *tcb);
/****************************************************************************
* Name: up_allocpage()
*
* Description:
* This architecture-specific function will set aside page in memory and map
* the page to its correct virtual address. Architecture-specific context
* information saved within the TCB will provide the function with the
* information needed to identify the virtual miss address.
*
* This function will return the allocated physical page address in vpage.
* The size of the underlying physical page is determined by the
* configuration setting CONFIG_PAGING_PAGESIZE.
*
* NOTE 1: This function must always return a page allocation. If all
* available pages are in-use (the typical case), then this function will
* select a page in-use, un-map it, and make it available.
*
* NOTE 2: If an in-use page is un-mapped, it may be necessary to flush the
* instruction cache in some architectures.
*
* NOTE 3: Allocating and filling a page is a two step process.
* up_allocpage() allocates the page, and up_fillpage() fills it with data
* from some non- volatile storage device. This distinction is made because
* up_allocpage() can probably be implemented in board-independent logic
* whereas up_fillpage() probably must be implemented as board-specific
* logic.
*
* NOTE 4: The initial mapping of vpage should be read-able and write-
* able (but not cached). No special actions will be required of
* up_fillpage() in order to write into this allocated page.
*
* Input Parameters:
* tcb - A reference to the task control block of the task that needs to
* have a page fill. Architecture-specific logic can retrieve page
* fault information from the architecture-specific context
* information in this TCB to perform the mapping.
*
* Returned Value:
* This function will return zero (OK) if the allocation was successful.
* A negated errno value may be returned if an error occurs. All errors,
* however, are fatal.
*
* Assumptions:
* - This function is called from the normal tasking context (but with
* interrupts disabled). The implementation must take whatever actions
* are necessary to assure that the operation is safe within this
* context.
*
****************************************************************************/
int up_allocpage(FAR struct tcb_s *tcb, FAR void **vpage);
/****************************************************************************
* Name: up_fillpage()
*
* Description:
* After a page is allocated and mapped by up_allocpage(), the actual
* filling of the page with data from the non-volatile, must be performed
* by a separate call to the architecture-specific function, up_fillpage().
* This function is non-blocking, it will start an asynchronous page fill.
* The common paging logic will provide a callback function, pg_callback,
* that will be called when the page fill is finished (or an error occurs).
* This callback is assumed to occur from an interrupt level when the
* device driver completes the fill operation.
*
* NOTE 1: Allocating and filling a page is a two step process.
* up_allocpage() allocates the page, and up_fillpage() fills it with data
* from some non- volatile storage device. This distinction is made because
* up_allocpage() can probably be implemented in board-independent logic
* whereas up_fillpage() probably must be implemented as board-specific
* logic.
*
* NOTE 2: The initial mapping of vpage will be read-able, write-able,
* but non-cacheable. No special actions will be required of
* up_fillpage() in order to write into this allocated page. If the
* virtual address maps to a text region, however, this function should
* remap the region so that is is read/execute only. It should be made
* cache-able in any case.
*
* Input Parameters:
* tcb - A reference to the task control block of the task that needs to
* have a page fill. Architecture-specific logic can retrieve page
* fault information from the architecture-specific context
* information in this TCB to perform the fill.
* pg_callbck - The function to be called when the page fill is complete.
*
* Returned Value:
* This function will return zero (OK) if the page fill was successfully
* started (the result of the page fill is passed to the callback function
* as the result argument). A negated errno value may be returned if an
* error occurs. All errors, however, are fatal.
*
* NOTE: -EBUSY has a special meaning. It is used internally to mean that
* the callback function has not executed. Therefore, -EBUSY should
* never be provided in the result argument of pg_callback.
*
* Assumptions:
* - This function is called from the normal tasking context (but
* interrupts siabled). The implementation must take whatever actions
* are necessary to assure that the operation is safe within this
* context.
* - Upon return, the caller will sleep waiting for the page fill callback
* to occur. The callback function will perform the wakeup.
*
****************************************************************************/
#ifdef CONFIG_PAGING_BLOCKINGFILL
int up_fillpage(FAR struct tcb_s *tcb, FAR void *vpage);
#else
typedef CODE void (*up_pgcallback_t)(FAR struct tcb_s *tcb, int result);
int up_fillpage(FAR struct tcb_s *tcb, FAR void *vpage,
up_pgcallback_t pg_callback);
#endif
#undef EXTERN
#if defined(__cplusplus)
}
#endif
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_PAGING */
#endif /* __INCLUDE_NUTTX_PAGE_H */
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