/****************************************************************************
* arch/arm/src/armv7/arm_pgalloc.c
*
* Copyright (C) 2014 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 <string.h>
#include <errno.h>
#include <debug.h>
#include <nuttx/sched.h>
#include <nuttx/arch.h>
#include <nuttx/addrenv.h>
#include "cache.h"
#include "mmu.h"
#if defined(CONFIG_MM_PGALLOC) && defined(CONFIG_ARCH_USE_MMU)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: alloc_pgtable
*
* Description:
* Add one page table to a memory region.
*
****************************************************************************/
static uintptr_t alloc_pgtable(void)
{
irqstate_t flags;
uintptr_t paddr;
FAR uint32_t *l2table;
uint32_t l1save;
/* Allocate one physical page for the L2 page table */
paddr = mm_pgalloc(1);
if (paddr)
{
DEBUGASSERT(MM_ISALIGNED(paddr));
/* Temporarily map the page into the virtual address space */
flags = irqsave();
l1save = mmu_l1_getentry(ARCH_SCRATCH_VBASE);
mmu_l1_setentry(paddr & ~SECTION_MASK, ARCH_SCRATCH_VBASE, MMU_MEMFLAGS);
l2table = (FAR uint32_t *)(ARCH_SCRATCH_VBASE | (paddr & SECTION_MASK));
/* Initialize the page table */
memset(l2table, 0, MM_PGSIZE);
/* Make sure that the initialized L2 table is flushed to physical
* memory.
*/
arch_flush_dcache((uintptr_t)l2table,
(uintptr_t)l2table + MM_PGSIZE);
/* Restore the scratch section page table entry */
mmu_l1_restore(ARCH_SCRATCH_VBASE, l1save);
irqrestore(flags);
}
return paddr;
}
/****************************************************************************
* Name: get_pgtable
*
* Description:
* Return the physical address of the L2 page table corresponding to
* 'vaddr'
*
****************************************************************************/
static int get_pgtable(FAR group_addrenv_t *addrenv, uintptr_t vaddr)
{
uint32_t l1entry;
uintptr_t paddr;
unsigned int hpoffset;
unsigned int hpndx;
/* The current implementation only supports extending the user heap
* region as part of the implementation of user sbrk().
*/
DEBUGASSERT(vadddr >= CONFIG_ARCH_HEAP_VBASE && vaddr < ARCH_HEAP_VEND);
/* Get the current level 1 entry corresponding to this vaddr */
hpoffset = vaddr - CONFIG_ARCH_HEAP_VBASE;
if (hpoffset >= ARCH_HEAP_SIZE)
{
return 0;
}
hpndx = hpoffset >> 20;
l1entry = (uintptr_t)addrenv->heap[hpndx];
if (l1entry == 0)
{
/* No page table has been allocated... allocate one now */
paddr = alloc_pgtable();
if (paddr != 0)
{
/* Set the new level 1 page table entry in the address environment. */
l1entry = paddr | MMU_L1_PGTABFLAGS;
addrenv->heap[hpndx] = (FAR uintptr_t *)l1entry;
/* And instantiate the modified environment */
(void)up_addrenv_select(addrenv, NULL);
}
}
return l1entry & ~SECTION_MASK;
}
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: pgalloc
*
* Description:
* If there is a page allocator in the configuration and if and MMU is
* available to map physical addresses to virtual address, then function
* must be provided by the platform-specific code. This is part of the
* implementation of sbrk(). This function will allocate the requested
* number of pages using the page allocator and map them into consecutive
* virtual addresses beginning with 'brkaddr'
*
* NOTE: This function does not use the up_ naming standard because it
* is indirectly callable from user-space code via a system trap.
* Therefore, it is a system interface and follows a different naming
* convention.
*
* Input Parameters:
* brkaddr - The heap break address. The next page will be allocated and
* mapped to this address. Must be page aligned. If the memory manager
* has not yet been initialized and this is the first block requested for
* the heap, then brkaddr should be zero. pgalloc will then assigned the
* well-known virtual address of the beginning of the heap.
* npages - The number of pages to allocate and map. Mapping of pages
* will be contiguous beginning beginning at 'brkaddr'
*
* Returned Value:
* The (virtual) base address of the mapped page will returned on success.
* Normally this will be the same as the 'brkaddr' input. However, if
* the 'brkaddr' input was zero, this will be the virtual address of the
* beginning of the heap. Zero is returned on any failure.
*
****************************************************************************/
uintptr_t pgalloc(uintptr_t brkaddr, unsigned int npages)
{
FAR struct tcb_s *tcb = sched_self();
FAR struct task_group_s *group;
FAR uint32_t *l2table;
irqstate_t flags;
uintptr_t paddr;
uint32_t l1save;
unsigned int index;
DEBUGASSERT(tcb && tcb->group);
group = tcb->group;
/* The current implementation only supports extending the user heap
* region as part of the implementation of user sbrk(). This function
* needs to be expanded to also handle (1) extending the user stack
* space and (2) extending the kernel memory regions as well.
*/
DEBUGASSERT((group->flags & GROUP_FLAG_ADDRENV) != 0);
/* brkaddr = 0 means that no heap has yet been allocated */
if (brkaddr == 0)
{
brkaddr = CONFIG_ARCH_HEAP_VBASE;
}
DEBUGASSERT(vadddr >= CONFIG_ARCH_HEAP_VBASE && brkaddr < ARCH_HEAP_VEND);
DEBUGASSERT(MM_ISALIGNED(brkaddr));
for (; npages > 0; npages--)
{
/* Get the physical address of the level 2 page table */
paddr = get_pgtable(&group->addrenv, brkaddr);
if (paddr == 0)
{
return 0;
}
/* Temporarily map the level 2 page table into the "scratch" virtual
* address space
*/
flags = irqsave();
l1save = mmu_l1_getentry(ARCH_SCRATCH_VBASE);
mmu_l1_setentry(paddr & ~SECTION_MASK, ARCH_SCRATCH_VBASE, MMU_MEMFLAGS);
l2table = (FAR uint32_t *)(ARCH_SCRATCH_VBASE | (paddr & SECTION_MASK));
/* Back up L2 entry with physical memory */
paddr = mm_pgalloc(1);
if (paddr == 0)
{
mmu_l1_restore(ARCH_SCRATCH_VBASE, l1save);
irqrestore(flags);
return 0;
}
/* The table divides a 1Mb address space up into 256 entries, each
* corresponding to 4Kb of address space. The page table index is
* related to the offset from the beginning of 1Mb region.
*/
index = (brkaddr & 0x000ff000) >> 12;
/* Map the .text region virtual address to this physical address */
DEBUGASSERT(l2table[index] == 0);
l2table[index] = paddr | MMU_L2_UDATAFLAGS;
brkaddr += MM_PGSIZE;
/* Make sure that the modified L2 table is flushed to physical
* memory.
*/
arch_flush_dcache((uintptr_t)&l2table[index],
(uintptr_t)&l2table[index] + sizeof(uint32_t));
/* Restore the scratch L1 page table entry */
mmu_l1_restore(ARCH_SCRATCH_VBASE, l1save);
irqrestore(flags);
}
return brkaddr;
}
#endif /* CONFIG_MM_PGALLOC && CONFIG_ARCH_USE_MMU */
