nuttx/mm/umm_heap/umm_sbrk.c
Xiang Xiao ddaa3e42b9 mm: Move the real implementation of mm_sbrk to sbrk
and remove mm_sbrk and kmm_sbrk since it's wrong to expose
sbrk to other heaps except the default userspace heap.

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
2021-07-05 08:02:08 +09:00

138 lines
4.4 KiB
C

/****************************************************************************
* mm/umm_heap/umm_sbrk.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 <assert.h>
#include <errno.h>
#include <unistd.h>
#include <nuttx/mm/mm.h>
#include <nuttx/addrenv.h>
#include <nuttx/pgalloc.h>
#include "umm_heap/umm_heap.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: sbrk
*
* Description:
* The sbrk() function is used to change the amount of space allocated
* for the calling process. The change is made by resetting the process's
* break value and allocating the appropriate amount of space. The amount
* of allocated space increases as the break value increases.
*
* The sbrk() function adds 'incr' bytes to the break value and changes
* the allocated space accordingly. If incr is negative, the amount of
* allocated space is decreased by incr bytes. The current value of the
* program break is returned by sbrk(0).
*
* Input Parameters:
* incr - Specifies the number of bytes to add or to remove from the
* space allocated for the process.
*
* Returned Value:
* Upon successful completion, sbrk() returns the prior break value.
* Otherwise, it returns (void *)-1 and sets errno to indicate the
* error:
*
* ENOMEM - The requested change would allocate more space than
* allowed under system limits.
* EAGAIN - The total amount of system memory available for allocation
* to this process is temporarily insufficient. This may occur even
* though the space requested was less than the maximum data segment
* size.
*
****************************************************************************/
FAR void *sbrk(intptr_t incr)
{
uintptr_t brkaddr;
uintptr_t allocbase;
unsigned int pgincr;
size_t bytesize;
int errcode;
DEBUGASSERT(incr >= 0);
if (incr < 0)
{
errcode = ENOSYS;
goto errout;
}
/* Get the current break address (NOTE: assumes region 0). If
* the memory manager is uninitialized, mm_brkaddr() will return
* zero.
*/
brkaddr = (uintptr_t)mm_brkaddr(USR_HEAP, 0);
if (incr > 0)
{
/* Convert the increment to multiples of the page size */
pgincr = MM_NPAGES(incr);
/* Allocate the requested number of pages and map them to the
* break address. If we provide a zero brkaddr to pgalloc(), it
* will create the first block in the correct virtual address
* space and return the start address of that block.
*/
allocbase = pgalloc(brkaddr, pgincr);
if (allocbase == 0)
{
errcode = EAGAIN;
goto errout;
}
/* Has the been been initialized? brkaddr will be zero if the
* memory manager has not yet been initialized.
*/
bytesize = pgincr << MM_PGSHIFT;
if (brkaddr == 0)
{
/* No... then initialize it now */
mm_initialize(USR_HEAP, "Umem", (FAR void *)allocbase, bytesize);
}
else
{
/* Extend the heap (region 0) */
mm_extend(USR_HEAP, (FAR void *)allocbase, bytesize, 0);
}
}
return (FAR void *)brkaddr;
errout:
set_errno(errcode);
return (FAR void *)-1;
}